Patent Publication Number: US-11656258-B2

Title: Radio field intensity measurement device, and radio field intensity detector and game console using the same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to radio field intensity measurement devices which can display radio field intensity of radio signals. In particular, the present invention relates to radio field intensity measurement devices which change color in accordance with radio intensity of a radio signal, utilizing a chromic material, and radio field intensity detectors and amusement devices (such as game consoles, game machines, toys or the like) using the radio field intensity measurement devices. 
     2. Description of the Related Art 
     In recent years, wireless devices using radio communication have been spreading due to development of electronics and the coming of an advanced information society, and have been utilized in various fields such as military affairs, medical treatment, communication, education, and commercial transaction. Radio communication using a radiowave as a communication medium takes the maximum advantages of radiowave that information can be transmitted instantly independent from time and distance, and one of the most important bases for human life and industry in modern society. 
     A radiowave is a kind of electromagnetic waves, and a wave propagated in the air by energy exchange between an electric field and a magnetic field. Since a radiowave cannot be seen, there is a concern that a radiowave emitted from facilities using radiowave and wireless devices may adversely affect human bodies. Thus, there is a need to provide a device which can easily measure radio field intensity of a radiowave emitted from a radio emission device, and display information on the radiowave. 
     There are various methods for measuring radio field intensity. For example, Reference 1, Japanese Published Patent Application No. 2006-23817, discloses a radio field detector in which an antenna, a rectifier circuit and a lamp are connected and radio field intensity is detected by light intensity of a lamp. Further, Reference 2, Japanese Published Patent Application No. 2001-165973, provides an electromagnetic wave monitor in which an antennal, a storage device, and an informing means are connected, and the informing means is driven by the storage device to measure a radio field intensity. 
       FIG.  38    is a block diagram illustrating a typical configuration of a radio field intensity measurement device disclosed in Reference 1. 
     In the radio field intensity measurement device  3800  illustrated in  FIG.  38   , a received radiowave  3820  is converted to an induction signal and the induction signal is input to a rectifier circuit  3811 . The rectifier circuit  3811  rectifies the induction signal and supplied power to the lamp  3812 . In other words, electricity which goes up in proportion to the intensity of the received radiowave  3820  is supplied to the lamp, and the intensity of the radiowave appears in the light intensity of the lamp which is turned on. 
     In the electromagnetic wave monitor in Reference 2, as the informing means, a light-emitting diode, a discharge lamp, or a liquid crystal display device is used. 
     SUMMARY OF THE INVENTION 
     However, the radio field intensity measurement device of Reference 1 has a problem of not detecting a weak radiowave, because the weak radiowave emitted over long distance lights the lamp, and thus sufficient power is difficult to secure. Further, in the electromagnetic wave monitor of Reference 2, a weak radiowave is measured to secure power to drive a light-emitting diode, a discharge lamp and a liquid crystal display device as the informing means. However, Reference 2 has a problem in that lighting of the informing means is difficult to be seen when brightness in surroundings is intense e.g., under sunlight. 
     The present invention has been made in view of the above problems. It is an object of the present invention to provide a radio field intensity measurement device which can measure a weak radiowave, and have a display portion which has a high level of visibility even when brightness in surroundings is intense e.g., under sunlight. 
     In order to solve the above problems, in accordance with the present invention, a battery is provided as a power source to supply power to a radio field intensity measurement device. The power to drive the radio field intensity measurement device is produced from a received radiowave, and charged in the battery. When a potential of a signal obtained from the received radiowave is higher than an output potential of the battery, the power is stored in the battery. On the other hand, when the potential of the signal obtained from the received radiowave is lower than the output potential of the battery, power produced by the battery is used as power to drive the radio field intensity measurement device. 
     A radio field intensity measurement device of the present invention employs a thermochromic material or an electrochromic (EC) material as an element to display radio field intensity, and includes a resistor or a voltage application element as a means of changing the color of such a chromic material. 
     An aspect of the present invention is a radio field intensity measurement device which comprises an antenna to convert a received radiowave to an induction signal; a rectifier circuit configured to output a direct signal by rectifying the induction signal; a battery to be charged by the direct signal; a control circuit configured to compare a potential of the direct signal with an output potential of the battery; an amplifier circuit configured to amplify the direct signal; and a display element which is operated depending on the direct signal amplified by the amplifier circuit. In the radio field intensity measurement device, the control circuit charges the battery when the potential of the direct signal is higher than the output potential of the battery, and when the potential of the direct signal is lower than the output potential of the battery, power of the battery is used as a power source to drive the amplifier circuit. 
     Another aspect of the present invention is a radio field intensity measurement device which comprises an antenna to convert a received radiowave to an induction signal; a rectifier circuit configured to output a direct signal by rectifying the induction signal; a battery to be charged by the direct signal; a control circuit configured to compare a potential of the direct signal with an output potential of the battery; an amplifier circuit configured to amplify the direct signal; and a display element which is operated depending on the direct signal amplified by the amplifier circuit. In the radio field intensity measurement device, the control circuit charges the battery when the potential of the direct signal is higher than the output potential of the battery, when the potential of the direct signal is lower than the output potential of the battery, power of the battery is used as a power source to drive the amplifier circuit, and a color of the display element is changed in accordance with a magnitude of the direct signal amplified by the amplifier circuit. 
     Another aspect of the present invention is a radio field intensity measurement device which comprises an antenna to convert a received radiowave to an induction signal; a rectifier circuit configured to output a direct signal by rectifying the induction signal; a battery to be charged by the direct signal; a control circuit configured to compare a potential of the direct signal with an output potential of the battery; an amplifier circuit configured to amplify the direct signal; and a display element which is operated depending on the direct signal amplified by the amplifier circuit. In the radio field intensity measurement device, the control circuit charges the battery when the potential of the direct signal is higher than the output potential of the battery, when the potential of the direct signal is lower than the output potential of the battery, power of the battery is used as a power source to drive the amplifier circuit, and the display element includes a resistance heating element and a thermochromic element. 
     Another aspect of the present invention is a radio field intensity measurement device which comprises an antenna to convert a received radiowave to an induction signal; a rectifier circuit configured to output a direct signal by rectifying the induction signal; a battery to be charged by the direct signal; a control circuit configured to compare a potential of the direct signal with an output potential of the battery; an amplifier circuit configured to amplify the direct signal; and a display element which is operated depending on the direct signal amplified by the amplifier circuit. In the radio field intensity measurement device, the control circuit charges the battery when the potential of the direct signal is higher than the output potential of the battery, when the potential of the direct signal is lower than the output potential of the battery, power of the battery is used as a power source to drive the amplifier circuit, and the display element includes a resistance heating element and a thermochromic element, and a color of the display element is changed in accordance with a magnitude of the direct signal amplified by the amplifier circuit. 
     In the present invention, the thermochromic element includes a thermotropic liquid crystal. 
     Another aspect of the present invention is a radio field intensity measurement device which comprises an antenna to convert a received radiowave to an induction signal; a rectifier circuit configured to output a direct signal by rectifying the induction signal; a battery to be charged by the direct signal; a control circuit configured to compare a potential of the direct signal with an output potential of the battery; an amplifier circuit configured to amplify the direct signal; and a display element which is operated depending on the direct signal amplified by the amplifier circuit. In the radio field intensity measurement device, the control circuit charges the battery when the potential of the direct signal is higher than the output potential of the battery, when the potential of the direct signal is lower than the output potential of the battery, power of the battery is used as a power source to drive the amplifier circuit, and the display element includes a voltage application element and an electrochromic element. 
     Another aspect of the present invention is a radio field intensity measurement device which comprises an antenna to convert a received radiowave to an induction signal; a rectifier circuit configured to output a direct signal by rectifying the induction signal; a battery to be charged by the direct signal; a control circuit configured to compare a potential of the direct signal with an output potential of the battery; an amplifier circuit configured to amplify the direct signal; and a display element which is operated depending on the direct signal amplified by the amplifier circuit. In the radio field intensity measurement device, the control circuit charges the battery when the potential of the direct signal is higher than the output potential of the battery, when the potential of the direct signal is lower than the output potential of the battery, power of the battery is used as a power source to drive the amplifier circuit, and the display element includes a voltage application element and an electrochromic element, and a color of the display element is changed in accordance with a magnitude of the direct signal amplified by the amplifier circuit. 
     In addition, in the present invention, the electrochromic element includes a metal oxide. 
     The battery of the present invention is a lithium battery, a lithium polymer battery, a lithium ion battery, a nickel hydride battery, a nickel cadmium battery, an organic radical battery, a lead-acid battery, an air secondary battery, a nickel zinc battery, a silver zinc battery, or a capacitor. 
     The capacitor of the present invention is an electric double layer capacitor. 
     The radio field intensity detector of the present invention is attached to an object to detect a radiowave. 
     An amusement device of the present invention comprises a plate-like radio field intensity detector attached with the radio field intensity detector and a radiowave emitter, and a color of the plate-like radio field intensity detector is changed by using a radiowave emitted from the radiowave emitter. 
     It is to be noted that description “be connected” in the present invention indicates electrical connection. Therefore, in structures disclosed in the present invention, another element capable of electrical connection (e.g., a switch, a transistor, a capacitor, an inductor, a resistor, a diode, or the like) may be interposed between elements having a predetermined connection relation. 
     The present invention provides a radio field intensity measurement device which can measure a weak radiowave from a long distance. Further, the present invention provides a radio field intensity measurement device which has a high level of visibility even when brightness in surroundings is intense e.g., under sunlight. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings:— 
         FIG.  1    is a view describing Embodiment Mode 1; 
         FIG.  2    is a view describing Embodiment Mode 1; 
         FIGS.  3 A to  3 E  are views describing Embodiment Mode 1; 
         FIG.  4    is a view describing Embodiment Mode 1; 
         FIG.  5    is a view describing Embodiment Mode 1; 
         FIG.  6    is a view describing Embodiment Mode 1; 
         FIGS.  7 A and  7 B  are views describing Embodiment Mode 1; 
         FIG.  8    is a view describing Embodiment Mode 1; 
         FIG.  9    is a view describing Embodiment Mode 1; 
         FIG.  10    is a view describing Embodiment Mode 1; 
         FIG.  11    is a view describing Embodiment Mode 1; 
         FIG.  12    is a view describing Embodiment Mode 1; 
         FIGS.  13 A and  13 B  are views describing Embodiment Mode 2; 
         FIGS.  14 A to  14 C  are views describing Embodiment Mode 2; 
         FIGS.  15 A and  15 B  are views describing Embodiment Mode 2; 
         FIG.  16    is a view describing Embodiment Mode 2; 
         FIGS.  17 A to  17 D  are views describing Embodiment 1; 
         FIGS.  18 A to  18 C  are views describing Embodiment 1; 
         FIGS.  19 A and  19 B  are views describing Embodiment 1; 
         FIGS.  20 A and  20 B  are views describing Embodiment 1; 
         FIGS.  21 A and  21 B  are views describing Embodiment 1; 
         FIGS.  22 A to  22 C  are views describing Embodiment 2; 
         FIGS.  23 A to  23 C  are views describing Embodiment 2; 
         FIGS.  24 A and  24 B  are views describing Embodiment 2; 
         FIGS.  25 A to  25 C  are views describing Embodiment 3; 
         FIGS.  26 A to  26 C  are views describing Embodiment 3; 
         FIGS.  27 A to  27 C  are views describing Embodiment 3; 
         FIGS.  28 A and  28 B  are views describing Embodiment 3; 
         FIGS.  29 A and  29 B  are views describing Embodiment 4; 
         FIGS.  30 A and  30 B  are views describing Embodiment 4; 
         FIGS.  31 A and  31 B  are views describing Embodiment 4; 
         FIGS.  32 A to  32 C  are views describing Embodiment 4; 
         FIGS.  33 A and  33 B  are views describing Embodiment 4; 
         FIGS.  34 A and  34 B  are views describing Embodiment 4; 
         FIGS.  35 A and  35 B  are views describing Embodiment 4; 
         FIGS.  36 A and  36 B  are views describing Embodiment 4; 
         FIGS.  37 A and  37 B  are views describing Embodiment 5; and 
         FIG.  38    is a view describing an object of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiment Modes 
     Embodiment Modes of the present invention will be explained below with reference to the accompanied drawings. It is easily understood by those skilled in the art that modes and details disclosed herein can be modified in various ways without departing from the spirit and the scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiment modes to be given below. It is to be noted that, in the present invention explained below, there is a case that similar portions or portions having a similar function are denoted by the same reference numerals through the drawings. 
     Embodiment Mode 1 
     Embodiment Mode 1 will describe a structure of a radio field intensity measurement device of the present invention. 
       FIG.  1    is a block diagram of a radio field intensity measurement device of the present invention. The radio field intensity measurement device  100  includes an antenna  110 , a rectifier circuit  111 , a control circuit  112 , a battery  113 , an amplifier circuit  114  and a display element  115 . Note that the rectifier circuit  111 , the control circuit  112  and the amplifier circuit  114  are collectively referred to as a signal processing circuit  120  for simple description. 
       FIG.  2    is a block diagram in which the antenna  110  receives a received radiowave  302  from a radiowave source  301 . In  FIG.  2   , the radiowave received by the antenna  110  is converted into an induction signal and input into the rectifier circuit  111 . The rectifier circuit  111  converts the induction signal to a direct signal and outputs the direct signal. In addition, the direct signal output from the rectifier circuit  111  is input into the battery  113  through the control circuit  112 . Meanwhile, the direct signal output from the rectifier circuit  111  is amplified by the amplifier circuit  114  and input into the display element  115 . The display element  115  changes color in accordance with the direct signal amplified by the amplifier circuit  114 . 
     The rectifier circuit  111 , for example as illustrated in  FIG.  4   , a diode  503 , a diode  504 , and a capacitor  505 , and an induction signal received by the antenna  110  is half-wave rectified by the diode  504  and smoothed by the capacitor  505 . The direct signal which is output from the rectifier circuit  111  and which is half-wave rectified and smoothed is supplied to the control circuit  112 . 
     The control circuit  112 , for example as illustrated in  FIG.  5   , includes a diode  604 , a diode  605 , a voltage comparison circuit  601 , a switch  602  and a switch  603 . 
     The voltage comparison circuit  601  compares an output potential of the battery  113  with a potential of a direct signal output from the rectifier circuit  111 . When the potential of the direct signal output from the rectifier circuit  111  is sufficiently higher than the output potential of the battery  113 , the voltage comparison circuit  601  turns the switch  602  on and the switch  603  off. Thus, current flows to the battery  113  from the rectifier circuit  111  through the diode  604  and the switch  602 . On the other, hand, when the potential of the direct signal output from the rectifier circuit  111  is not sufficiently higher than the output potential of the battery  113 , the voltage comparison circuit  601  turns the switch  602  off and the switch  603  on. At this time, when the potential of the direct signal output from the rectifier circuit  111  is higher than the output potential of the battery  113 , no current flows to the diode  605 . On the other hand, when the potential of the direct signal output from the rectifier circuit  111  is lower than the output potential of the battery  113 , current flows to the amplifier circuit  114  from the battery  113  through the switch  603  and the diode  605 . 
     Note that the control circuit is not limited to the example in Embodiment Mode 1, and may employs any mode. 
     As a switch employed in this specification, a transistor (e.g., a bipolar transistor or a MOS transistor), a diode (e.g., a PN diode, a PIN diode, a Schottky diode, a MIM (Metal Insulator Metal) diode, a MIS (Metal Insulator Semiconductor) diode, or a diode-connected transistor), a thyristor, or the like can be used. Alternatively, a logic circuit combining such elements can be used as a switch. 
       FIG.  6    illustrates an example of the voltage comparison circuit  601 . 
     By the voltage comparison circuit  601 , a voltage output from the battery  113  is divided by resistors  701  and  702 , and a voltage output from the rectifier circuit  111  is divided by resistors  703  and  704 . Then, the voltages divided by the resistors are input to a comparator  705 . Buffers  706  and  707  of inverter topologies are connected in series with an output of the comparator  705 . Then, an output of the buffer  706  is input to a control terminal of the switch  603 , and an output of the buffer  707  is input to a control terminal of the switch  602 , so that on/off of the switches  602  and  603  in  FIG.  6    is controlled. Note that when H-level signals are input to the control terminals of the switches  602  and  603 , the switches  602  and  603  are turned on, whereas when L-level signals are input, the switches  602  and  603  are turned off. 
     By regulating a voltage input to the comparator  705  by dividing an incoming voltage with the resistors, it becomes possible to control the timings for turning the switch  602  on and turning the switch  603  off at a point when the voltage output from the rectifier circuit becomes higher than the voltage output from the battery  113  by a certain level. Similarly, it becomes possible to control the timings for turning the switch  602  off and turning the switch  603  on at a point when the voltage output from the rectifier circuit becomes lower than the voltage output from the battery  113  by a certain level. 
     Note that the voltage comparison circuit is not limited to this example in this embodiment mode, and may employ any mode. 
     With reference to the timing chart of  FIG.  9   , operation of the voltage comparison circuit is described. A first waveform  1001  is a change of a potential after the division by the resistors  701  and  702  in  FIG.  6   . A second waveform  1002  is a change of a potential after the division by the resistors  703  and  704  in  FIG.  6   . A first signal  1010  is a control signal which is output from the comparator  705  and is input to the buffer  706  in  FIG.  6   . A second signal  1011  is a control signal which is output from the buffer  706  and is input to a control terminal of the switch  603  in  FIG.  6   . A third signal  1012  is a control signal which is output from the buffer  707  and is input to a control terminal of the switch  602  in  FIG.  6   . For simple description, a signal which is input to the rectifier circuit  111  from the antenna  110  before rectification is denoted by a waveform before rectification  1020  (a waveform of an induction signal). 
     In  FIG.  9   , when the potential of the first waveform  1001  is higher than that of the second waveform  1002 , i.e., when the amplitude of the waveform before rectification which is a signal before rectification is large, the first signal  1010  is at a high potential level (hereinafter, abbreviated as H), the second signal  1011  at a low potential level (hereinafter, abbreviated as L), and the third signal  1012  is H. Accordingly, the switch  603  to which L of the second signal  1011  is input is turned off, and the switch  602  to which H of the third signal  1012  is input is turned on. Thus, the battery  113  is charged as illustrated in  FIG.  10   . The period in which the battery  113  is charged is regarded as a charge period  1030 , and during this charge period  1030 , the amplifier circuit  114  uses power output from the rectifier circuit  111 . 
     In  FIG.  9   , when the potential of the first waveform  1001  is lower than that of the second waveform  1002 , i.e., the amplitude of the waveform before rectification  1020  which is a signal before rectification, is small, the first signal  1010 , the second signal  1011  and the third signal  1012  are L, H, and L respectively. Accordingly, the switch  603  to which H of the second signal  1011  is input is turned on, and the switch  602  to which L of the third signal  1012  is input is turned off. Thus, the battery  113  is discharged as illustrated in  FIG.  11   . The period in which the battery  113  is discharged is regarded as a discharge period  1031 , and during this discharge period  1031 , the amplifier circuit  114  uses power output from the battery  113 . 
     Therefore, the amplifier circuit  114  receives power either in the charge period  1030  or the discharge period  1031 . 
     Non-limiting examples of the battery  113  includes secondary batteries such as a lithium ion battery, a lithium secondary battery, a nickel metal hydride battery, a nickel cadmium battery, and an organic radical battery. Alternatively, a capacitor having large capacity may be used. 
     Note that the term “charge” indicates that current flows to the battery  113 , so that power is stored in the battery  113 . Specifically, in a secondary battery, “charge” means that electric energy input to the battery  113  is converted to chemical energy to be stored. On the other hand, the term “discharge” indicates that chemical energy in the battery  113  is converted to electric energy to be output. 
     A capacitor having large capacity which can be used as the battery  113  of the present invention is preferably a capacitor having electrodes whose opposed areas are large. In particular, it is preferable to use an electric double layer capacitor which is formed from an electrode material having a large specific surface area such as activated carbon, fullerene, or a carbon nanotube. A capacitor has a simpler structure than a battery. Further, a capacitor can be easily formed to be thin and formed by stacking layers. An electric double layer capacitor has a function of storing power and will not deteriorate so much even after it is charged and discharged a large number of times. Further, the electric double layer capacitor has an excellent property in that it can be charged rapidly. 
     For the display element  115 , an element including a material exhibiting a chromism phenomenon, such as a thermochromic material or an electrochromic material, can be used, but not limited to such an element. 
     Next, with reference to the timing chart of  FIG.  12   , operation of the radio field intensity measurement device is described. A first waveform  1201  is a potential change of a direct signal which is rectified in the rectifier circuit  111  and is input to the amplifier circuit  114  in  FIG.  2   . A second waveform  1202  is a potential change of a signal which is output from the control circuit  112  and is input to the amplifier circuit  114  as power in  FIG.  2   . Note that the second waveform  1202  is the same as the second waveform  1002  in  FIG.  9   . A third waveform  1203  is a potential change of voltage, which is obtained by amplifying the first waveform  1201  input into the amplifier circuit  114  in  FIG.  2    with the amplifier circuit  114  to be input to the display element  115 . For simple description, a signal which is input to the rectifier circuit  111  from the antenna  110  before rectification is denoted by a waveform before rectification  1220  (a waveform of an induction signal). A period in which the waveform before rectification  1220  is small is denoted by a weak radiowave period  1221 , and a period in which the waveform before rectification  1220  is large is denoted by a strong radiowave period  1222 , and the minimum operation voltage of the display element  115  is denoted by reference numeral  1223 . The minimum operation voltage is a minimum voltage at which the display element  115  can cause color change which is visible to human eyes. 
     In  FIG.  12   , in the weak radiowave period  1221 , the first waveform  1201  is amplified as shown by the third waveform  1203 . In addition, also in the strong radiowave period  1222 , the first waveform  1201  is amplified as shown by the third waveform  1203 . In this case, the ratio of increase from the first waveform  1201  to the third waveform (V 2 /V 1 ) is referred to as an amplification ratio. Note that the amplifier circuit  114  may have such an amplification ratio that the third waveform after amplification exceeds the minimum operation voltage  1223 . 
     Therefore, the display element  115  can operate either in the weak radiowave period  1221  or the strong radiowave period  1222 . 
     Then,  FIG.  7 A  schematically illustrates of a radio field intensity measurement device of the present invention. 
     The radio field intensity measurement device illustrated in  FIG.  7 A  includes an antenna  810 , a signal processing circuit  811 , a battery  812  and a display element  813  over a substrate  801 . The antenna  810  includes a connection terminal  820  and a connection terminal  821 . The connection terminals  820  and  821  of the antenna  810  are both connected to the signal processing circuit  811 . 
     As a transistor which can be used for the signal processing circuit  811 , various types of transistors can be applied without being limited to particular types of transistors. Accordingly, a thin film transistor (TFT) using a non-single crystalline semiconductor film typified by amorphous silicon or polycrystalline silicon, a transistor formed by using a semiconductor substrate or an SOI substrate, a MOS transistor, a junction transistor, a bipolar transistor, a transistor using a compound semiconductor such as ZnO or a-InGaZnO, a transistor using an organic semiconductor or a carbon nanotube, or other transistors can be applied. Note that a non-single crystalline semiconductor film may include hydrogen or halogen. 
     In addition, various types of substrates can be employed as the substrate  801  without particular limitations. Accordingly, for example, a single crystalline substrate, an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a paper substrate, a cellophane substrate, a stone substrate, or the like can be used. In addition, the signal processing circuit  811  may be formed over one substrate, and then the signal processing circuit  811  may be transferred to another substrate. 
     There are no particular limitations on the shape of the antenna  810 . For example, as illustrated in  FIG.  3 A , an antenna  403  may be provided in the whole area around a signal processing circuit  402  over a substrate  401 . As illustrated in  FIG.  3 B , a thin antenna  403  may be provided in the area around the signal processing circuit  402  over the substrate  401 . As illustrated in  FIG.  3 C , the antenna may have such a shape that receives a high frequency electromagnetic wave. As illustrated in  FIG.  3 D , the antenna may have a 180-degree nondirectional shape. As illustrated in  FIG.  3 E , the antenna may have a stick-like elongated shape. For example, the shape such as a so-called dipole antenna, a loop antenna, a Yagi antenna, a patch antenna, or a minute antenna can be employed. 
     Although  FIGS.  3 A to  3 E  do not illustrate elements corresponding to the battery and the display element for simple description, the radio field intensity measurement device according to Embodiment Mode 1 includes a battery and a display element. 
     The antenna  810  illustrated in  FIG.  7 A  may be formed over the substrate provided with the signal processing circuit  811  or a substrate different from the substrate provided with the signal processing circuit  811 . Various types of substrates can be used as a substrate to be provided with the antenna  810 , and not-limiting examples of the substrate includes a single crystalline substrate, an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a paper substrate, a cellophane substrate, a stone substrate and the like. In the case where the antenna  810  is formed over the same substrate as the signal processing circuit  811 , the antenna  810  may be formed by depositing a conductive film by sputtering, CVD, spin coating, or the like and then patterning the conductive film; or the antenna  810  may be formed by a droplet discharge method typified by an ink-jet method, a screen printing method, or the like. Also in the case where the antenna  810  is formed over a substrate which is different from the substrate over which the signal processing circuit  811  is formed, the antenna  810  can be formed by any of the aforementioned methods; however, preferably, the antenna  810  is formed by the screen printing method. 
     There are no particular limitations on the method of connecting the substrate provided with the signal processing circuit to the antenna. For example, wire bonding or a bump may be adopted to connect the antenna and the substrate provided with the signal processing circuit, or a method where a surface of the substrate provided with a signal processing circuit formed in a chip form is made as an electrode and the electrode is attached to the antenna may be employed. In this method, an anisotropic conductive film (ACF) can be used to connect the antenna and the substrate. 
     In addition, an appropriate length of the antenna varies depending on a frequency for receiving signals. For example, when the frequency is 2.45 GHz, a half-wave dipole antenna may have a length of a half wavelength (about 60 mm), or a monopole antenna may have a length of a quarter wavelength (about 30 mm). 
     The antenna may include a means of changing frequency of a received signal. For example, when a loop antenna is used for the antenna, a resonant circuit may be formed from an antenna coil  901  and a capacitor  902  included in the antenna  110  as illustrated in  FIG.  8   . 
     Further, in  FIG.  7 A , the antenna  810  is formed over the same substrate as the signal processing circuit  811 , or may be provided as an external antenna. As illustrated in  FIG.  7 A , when the antenna  810  is formed over the same substrate  801  as the signal processing circuit  811 , the shape of the antenna is preferably a shape of a minute loop antenna, a minute dipole antenna or the like. 
     As the battery  812 , secondary batteries can be used, such as a lithium ion battery, a lithium secondary battery, a nickel hydride battery, a nickel cadmium battery, an organic radical battery, a lead-acid battery, an air secondary battery, a nickel zinc battery, a silver zinc battery, and the like. The battery is not limited to these examples, and a high-capacity capacitor may be used. In particular, a lithium ion battery and a lithium secondary battery have high charging and discharging capacity. Therefore, such a lithium ion battery or such a lithium secondary battery can be used as a battery provided for the radio field intensity measurement device of Embodiment Mode 1 in the present invention, and thus miniaturization thereof can be achieved. It is to be noted that an active material or an electrolyte of a lithium ion battery is formed by a sputtering method; therefore, the battery  812  may be formed over a substrate over which the signal processing circuit  811  is formed or a substrate over which the antenna  810  is formed. The battery  812  is formed over the substrate over which the signal processing circuit  811  or the antenna  810  is formed, and thus yield is improved. In a metal lithium battery, a transition metal oxide including lithium ions, a metal oxide, a metal sulfide, an iron compound, a conductive polymer, an organic sulfur compound, or the like is used for an anode active material; lithium (alloy) is used for a cathode active material; and an organic electrolyte solution, a polymer electrolyte, or the like is used for an electrolyte. Therefore, the battery  812  can have higher charging and discharging capacity. 
     For the display element  813 , an element including a material exhibiting chromism phenomena, such as a thermochromic material or an electrochromic material, can be used, but not limited to this element. In particular, as an element including a thermochromic material (also referred to as a thermochromic element), an element including a thermotropic liquid crystal (also referred to as a thermochromic liquid crystal), especially an element including a cholesteric liquid crystal is preferable, and the cholesteric liquid crystal may include cholesteryl oleyl carbonate, cholesteryl nonanoate, or cholesteryl benzoate. In addition, as the element including the electrochromic material (also referred to as an electrochromic element), an element including a metal oxide such as tungsten oxide or a related compound thereof may be used. 
     The structure of the radio field intensity measurement device according to Embodiment Mode 1 in the present invention is not limited to that of  FIG.  7 A . For example, in  FIG.  7 B , the signal processing circuit  811  is provided between the antenna  810  and the battery  812 ; however, the battery  812  may be provided between the antenna  810  and the signal processing circuit  811  or the antenna  810  may be provided between the battery  812  and the signal processing circuit  811 . The area ratio of the antenna  810 , the battery  812  and the signal processing circuit  811  is not limited to the example of  FIGS.  7 A and  7 B . In other words, in the case where each layer in the cross-section of the radio field intensity measurement device according to this embodiment mode in the present invention is seen, there are no particular limitations on the positional relationship of the antenna  810 , the battery  812  and the signal processing circuit  811 . In addition, the antenna  810  and the signal processing circuit  811  may be formed over different substrates, or the antenna  810 , the signal processing circuit  811 , and the battery  812  may be formed over the same substrate. Note that, preferably, the display element  813  is disposed in the uppermost layer for improving visibility and has a large area. 
     The radio field intensity measurement device of Embodiment Mode 1 in the present invention has a battery which can store power, and replacing batteries is not needed. Furthermore, even when a received signal is weak, power can be supplied from the battery to the signal processing circuit, and thus the radio field intensity measurement device can operate to measure the intensity of the radiowave. In other words, since the radio field intensity measurement device can measure the intensity of the radiowave having a weak signal, sensitivity improvement and stable measurement of the radio field intensity measurement device can be achieved. 
     Moreover, when a received signal is strong, the battery can be automatically charged, and thus it is unnecessary that a user bothers charging. Needless to say, if the power stored in the battery becomes small, a user can easily charge the battery by himself/herself. 
     Embodiment Mode 2 
     Embodiment Mode 2 will describe a mode in which a display element including a thermochromic material is formed. 
       FIGS.  13 A and  13 B  schematically illustrate a display element in the present invention. A display element  2500  includes a resistance heating element  2502 , a thermochromic material  2503 , a transparent substrate  2504 , a connection terminal  2510  and a connection terminal  2511  over a light-shielding substrate  2501 . One of the connection terminals  2510  and  2511  is connected to a power supply terminal. For example, one of the connection terminals  2510  and  2511  is connected to the amplifier circuit  114  in Embodiment Mode 1. Note that the other of the connection terminals  2510  and  2511 , which is not connected to the power supply terminal, is connected to a GND terminal. 
     The structure of the display element in Embodiment Mode 2 is not limited to that in  FIGS.  13 A and  13 B . For example, the thermochromic material  2503  is arranged above the resistance heating element  2502  in  FIGS.  13 A and  13 B ; alternatively the resistance heating element  2502  may be arranged over the thermochromic material  2503 . The shape and area of the resistance heating element  2502  and the thermochromic material  2503  are not limited to those of  FIGS.  13 A and  13 B . For example, a comb-like shape or a convex-concave shape may be employed. Wider areas of the resistance heating element  2502  and the thermochromic material  2503  are preferably in contact with each other to enhance thermal conductivity. 
     In this embodiment mode, “the resistance heating element” indicates general elements which generate heat by electrical power. The amount of generated heat is changed in accordance with the power amount supplied from a connection terminal to the resistance heating element. Various substances can be used as materials of the resistance heating element in this embodiment mode. Thus, there are no particular limitations on the applicable material for the resistance hating element. 
     The thermochromic material in this embodiment mode indicates general substances which exhibit thermochromism phenomena. The thermochromism phenomenon is phenomena that color of a material is reversibly changed by heat stimulation. Thus, color is changed depending on the amount of heat supplied from the resistance heating element  2502 . In other words, color is changed in accordance with the amount of power supplied to the display element through the connection terminal. Various substances can be used as a thermochromic material included in the display element of this embodiment mode. Thus, there are no particular limitations on the type of the applicable thermochromic material. 
     A cholesteric liquid crystal, which is one example of thermochromic material in this embodiment mode, has a feature that a torsional state of the helix is changed depending on temperature. The molecular structure of the cholesteric liquid crystal and the principal of color change depending on the change of the molecular structure of the cholesteric liquid crystal are described with reference to  FIGS.  14 A,  14 B  and  FIGS.  15 A,  15 B . 
     The cholesteric liquid crystal preferably includes cholesteryl oleyl carbonate in which one side of a carbonate group  2100  is bound to a cholesteryl group  2101  and the other side of the carbonate group is bound to an oleyl group  2102  which is a straight-chain hydrocarbon group as illustrated in  FIG.  14 A . In  FIG.  14 A , cholesteryl oleyl carbonate, a compound in which the carbonate group  2100  and the oleyl group  2102  are bound to the cholesteryl group  2101  is shown. Cholesteryl benzoate, a compound in which a benzoate group  2103  is bonded to the cholesteryl group  2101 , instead of the carbonate group  2100  and the oleyl group  2102 , as illustrated in  FIG.  14 B , or cholesteryl nanoate, a compound in which a nanoate group  2104  is bonded to the cholesteryl group  2101 , instead of the carbonate group  2100  and the oleyl group  2102 , as illustrated in  FIG.  14 C  may be used. The mixed ratio of liquid crystal molecules including different straight-chain hydrocarbons such as cholesteryl oleyl carbonate, cholesteryl nononate, and cholesteryl benzoate is changed to change the color of the cholesteric liquid crystal. 
     The cholesteric liquid crystal has a helical molecular structure and partially reflects incident light. This reflecting property is changed depending on the torsional state of the helix. For example, a cholesteric liquid crystal molecule having a pitch P selectively reflects only a wavelength (λ=n (refractive index of a cholesteric liquid crystal)×P) of wavelengths included in incident light. For example, the liquid crystal molecule  2002  of  FIG.  15 A  has a torsion corresponding to ¼ pitch in a distance d between a transparent substrate  2000  and a light-shielding substrate  2001 , and thus only a wavelength (λ=n×P=n×4d) of wavelengths included in the incident light  2003  is selectively reflected. In addition, a liquid crystal molecule  2002  illustrated in  FIG.  15 B  has a torsion corresponding to ¾ pitch in the distance d, and thus a wavelength (λ=n×P=n×4/3d) of wavelengths included in the incident light  2003  is selectively reflected. 
     Human eyes recognize a difference in a wavelength of light as a difference of a color. Therefore, reflection light  2004  of  FIG.  15 A  and reflection light  2004  of  FIG.  15 B  have different wavelengths and are recognized as different colors. 
     The transparent substrate  2000  illustrated in  FIGS.  15 A and  15 B  may be transparent to human eyes. Preferably, the substrate transmits all wavelengths. The light-shielding substrate  2001  illustrated in  FIGS.  15 A and  15 B  may be a substrate which is black to human eyes. Preferably, the substrate absorbs all wavelengths. 
       FIG.  16    is a cross-sectional view illustrating a thermochromic element which is a display element including a thermochromic material. Wirings  2203   a  and  2203   b  are provided over the light-shielding substrate  2201  with a base layer  2202  interposed therebetween. The wiring  2203   a  and the wiring  2203   b  are connected to a resistance heating element  2229  in a contact portion  2206  and a contact portion  2207  provided in an interlayer insulating film  2204  and an insulating film  2205 . The resistance heating element  2229  generates heat by current flowing between the contact opening portion  2206  and the contact opening portion  2207  to heat a thermochromic material  2211 . Note that the wirings  2203   a  and  2203   b  are connected to connection terminals in  FIG.  13   . 
     A transparent substrate  2214  is disposed opposite to the light-shielding substrate  2201 . A thermochromic material  2211  is provided between the light-shielding substrate  2201  and the transparent substrate  2214 . The distance between the light-shielding substrate  2201  and the transparent substrate  2214  is kept by a spacer  2210 . After a thermochromic material  2211  is provided between the light-shielding substrate  2201  and the transparent substrate  2214 , the light-shielding substrate  2201  and the transparent substrate  2214  are fixed by a sealing material  2220 . It is preferable that the distance between the light-shielding substrate  2201  and the transparent substrate  2214  is narrow, since a small amount of the thermochromic material  2211  is used and the heat amount of the thermochromic material  2211  to be heated is small, which achieves rapid color change. 
     In such a display element, by voltage application to the resistance heating element  2229 , the heat amount supplied to the thermochromic material  2211  is changed, and thus the state of the thermochromic material  2211  is changed, so that a color tone reflection light  2231  is different from that of incident light  2230 . 
     Embodiment 1 
     Embodiment 1 will describe an example of a method for manufacturing the radio field intensity measurement device shown in the above-described embodiment modes with reference to drawings. In this embodiment, a structure in which an antenna, and a signal processing circuit of the radio field intensity measurement device are formed using thin film transistors over the same substrate will be explained. It is to be noted that when an antenna and a signal processing circuit are formed together over the same substrate, reduction in size of the radio field intensity measurement device can be achieved, which is advantageous. In addition, in this embodiment, an example will be explained, in which a thin-film secondary battery is used as the battery in the signal processing circuit. Needless to say, instead of the secondary battery, a capacitor such as an electric double layer capacitor may be used. 
     First, a peeling layer  1303  is formed over one surface of a substrate  1301  with an insulating film  1302  interposed therebetween, and then an insulating film  1304  functioning as a base film and a semiconductor film (e.g., a film containing amorphous silicon)  1305  are stacked thereover (see  FIG.  17 A ). It is to be noted that the insulating film  1302 , the peeling layer  1303 , the insulating film  1304 , and the semiconductor film  1305  can be formed consecutively. 
     The substrate  1301  is selected from a glass substrate, a quartz substrate, a metal substrate (e.g., a ceramic substrate or a stainless steel substrate), a semiconductor substrate such as a Si substrate, or the like. Alternatively, a plastic substrate made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), acrylic, or the like can be used. In this process, although the peeling layer  1303  is provided over the entire surface of the substrate  1301  with the insulating film  1302  interposed therebetween, the peeling layer  1303  can also be selectively formed by photolithography after being provided over the entire surface of the substrate  1301 . 
     The insulating films  1302  and  1304  are formed using insulating materials such as silicon oxide, silicon nitride, silicon oxynitride (SiO x N y , where x&gt;y&gt;0), or silicon nitride oxide (SiN x O y , where x&gt;y&gt;0) by a CVD method, a sputtering method, or the like. For example, when each of the insulating films  1302  and  1304  is formed to have a two-layer structure, a silicon nitride oxide film may be formed as a first insulating film and a silicon oxynitride film may be formed as a second insulating film. In addition, a silicon nitride film may be formed as a first insulating film and a silicon oxide film may be formed as a second insulating film. The insulating film  1302  functions as a blocking layer which prevents an impurity element contained in the substrate  1301  from getting mixed into the peeling layer  1303  or elements formed thereover. The insulating film  1304  functions as a blocking layer which prevents an impurity element contained in the substrate  1301  or the peeling layer  1303  from getting mixed into elements formed over the insulating film  1304 . In this manner, providing the insulating films  1302  and  1304  which function as the blocking layers can prevent adverse effects on the elements formed over the peeling layer  1303  or the insulating film  1304 , which would otherwise be caused by an alkali metal such as Na or an alkaline earth metal contained in the substrate  1301  or by the impurity element contained in the peeling layer  1303 . It is to be noted that when quartz is used for the substrate  1301 , for example, the insulating films  1302  and  1304  may be omitted. 
     The peeling layer  1303  may be formed using a metal film, a stacked structure of a metal film and a metal oxide film, or the like. As a metal film, either a single layer or stacked layers is/are formed using an element selected from tungsten (W), molybdenum (Mo), titanium (Ti), tantalum (Ta), niobium (Nb), nickel (Ni), cobalt (Co), zirconium (Zr), zinc (Zn), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), and iridium (Ir), or an alloy material or a compound material containing such an element as its main component. In addition, such materials can be formed by a sputtering method, various CVD methods such as a plasma CVD method, or the like. A stacked structure of a metal film and a metal oxide film can be obtained by the steps of forming the above-described metal film, applying plasma treatment thereto under an oxygen atmosphere or an N 2 O atmosphere or applying heat treatment thereto under an oxygen atmosphere or an N 2 O atmosphere, and thereby forming oxide or oxynitride of the metal film on the surface of the metal film. For example, when a tungsten film is provided as a metal film by a sputtering method, a CVD method, or the like, a metal oxide film of tungsten oxide can be formed on the surface of the tungsten film by application of plasma treatment to the tungsten film. In that case, the tungsten oxide can be represented by WO x  where x is in the range of 2 to 3. For example, there are cases where x is 2 (WO 2 ), x is 2.5 (W 2 O 5 ), x is 2.75 (W 4 O 11 ), x is 3 (WO 3 ), and the like. When tungsten oxide is formed, there is no particular limitation on the value of x, and thus, which of the above oxides is to be formed may be determined base on the etching rate or the like. In addition, after a metal film (e.g., tungsten) is formed, an insulating film formed of silicon oxide (SiO 2 ) or the like may be formed over the metal film by a sputtering method, and also metal oxide (e.g., tungsten oxide on tungsten) may be formed on the metal film. Moreover, high-density-plasma treatment as described above may be applied as the plasma treatment, for example. Besides, metal nitride or metal oxynitride may also be formed. In that case, plasma treatment or heat treatment may be applied to the metal film under a nitrogen atmosphere or an atmosphere containing nitrogen and oxygen. 
     The amorphous semiconductor film  1305  is formed with a thickness of 25 to 200 nm (preferably, 30 to 150 nm) by a sputtering method, an LPCVD method, a plasma CVD method, or the like. 
     Next, the amorphous semiconductor film  1305  is crystallized by laser irradiation. Alternatively, the crystallization of the amorphous semiconductor film  1305  may be performed by a method combining the laser crystallization with a thermal crystallization method using RTA or an annealing furnace or with a thermal crystallization method using a metal element that promotes the crystallization. After that, the crystallized semiconductor film is etched into a desired shape, whereby crystalline semiconductor films  1305   a  to  1305   f  are formed. Then, a gate insulating film  1306  is formed so as to cover the semiconductor films  1305   a  to  1305   f  (see  FIG.  17 B ). 
     The gate insulating film  1306  is formed using an insulating material such as silicon oxide, silicon nitride, silicon oxynitride (SiO x N y , where x&gt;y&gt;0), or silicon nitride oxide (SiN x O y , where x&gt;y&gt;0) by a CVD method, a sputtering method, or the like. For example, when the gate insulating film  1306  is formed to have a two-layer structure, it is preferable to form a silicon oxynitride film as a first insulating film and form a silicon nitride oxide film as a second insulating film. Alternatively, it is also preferable to form a silicon oxide film as a first insulating film and form a silicon nitride film as a second insulating film. 
     An example of a formation process of the crystalline semiconductor films  1305   a  to  1305   f  is briefly explained below. First, an amorphous semiconductor film with a thickness of 50 to 60 nm is formed by a plasma CVD method. Then, a solution containing nickel which is a metal element that promotes crystallization is retained on the amorphous semiconductor film, which is followed by dehydrogenation treatment (500° C. for one hour) and thermal crystallization treatment (550° C. for four hours). Thus, a crystalline semiconductor film is formed. Then, the crystalline semiconductor film is subjected to laser irradiation and then a photolithography process to form the crystalline semiconductor films  1305   a  to  1305   f . It is to be noted that crystallization of the amorphous semiconductor film may be performed only by laser irradiation, not by thermal crystallization which uses a metal element that promotes crystallization. 
     As a laser oscillator used for crystallization, either a continuous wave laser (a CW laser) or a pulsed laser can be used. As a laser that can be used here, there are gas lasers such as an Ar laser, a Kr laser, and an excimer laser; a laser whose medium is single-crystalline YAG, YVO 4 , forsterite (Mg 2 SiO 4 ), YAlO 3 , or GdVO 4  or polycrystalline (ceramic) YAG, Y 2 O 3 , YVO 4 , YAlO 3 , or GdVO 4  doped with one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as a dopant; a glass laser; a ruby laser; an alexandrite laser; a Ti:sapphire laser; a copper vapor laser; and a gold vapor laser. When irradiation is performed with the fundamental wave of such a laser beam or the second to fourth harmonics of the fundamental wave, crystals with a large grain size can be obtained. For example, the second harmonic (532 nm) or the third harmonic (355 nm) of an Nd:YVO 4  laser (the fundamental wave of 1064 nm) can be used. In this case, a laser power density of approximately 0.01 to 100 MW/cm 2  (preferably, 0.1 to 10 MW/cm 2 ) is needed, and irradiation is performed with a scanning rate of approximately 10 to 2000 cm/sec. It is to be noted that the laser whose medium is single crystal YAG, YVO 4 , forsterite (Mg 2 SiO 4 ), YAlO 3 , or GdVO 4  or polycrystalline (ceramic) YAG, Y 2 O 3 , YVO 4 , YAlO 3 , or GdVO 4  doped with one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as a dopant; an Ar ion laser, or a Ti:sapphire laser can be used as a CW laser, whereas it can also be used as a pulsed laser with a repetition rate of 10 MHz or more by a Q-switch operation, mode locking, or the like. When a laser beam with a repetition rate of 10 MHz or more is used, a semiconductor film is irradiated with the next pulse during the period in which the semiconductor film has been melted by the laser beam and is solidified. Therefore, unlike the case of using a pulsed laser with a low repetition rate, a solid-liquid interface in the semiconductor film can be continuously moved. Thus, crystal grains which have grown continuously in the scanning direction can be obtained. 
     The gate insulating film  1306  may be formed by oxidization or nitridation of the surfaces of the semiconductor films  1305   a  to  1305   f  by the above-described high-density plasma treatment. For example, plasma treatment with a mixed gas of a rare gas such as He, Ar, Kr, or Xe, and oxygen, nitrogen oxide (NO 2 ), ammonia, nitrogen, or hydrogen is conducted. When plasma is excited by the introduction of microwaves, plasma with a low electron temperature and high density can be generated. With oxygen radicals (which may include OH radicals) or nitrogen radicals (which may include NH radicals) which are generated by the high-density plasma, the surfaces of the semiconductor films can be oxidized or nitrided. 
     By such high-density plasma treatment, an insulating film with a thickness of 1 to 20 nm, typically 5 to 10 nm, is formed on the semiconductor films. Since the reaction in this case is a solid-phase reaction, the interface state density between the insulating film and the semiconductor films can be quite low. Since such high-density plasma treatment directly oxidizes (or nitrides) the semiconductor films (crystalline silicon or polycrystalline silicon), desirably, the insulating film can be formed with extremely little unevenness. In addition, since crystal grain boundaries of crystalline silicon are not strongly oxidized, an excellent state is obtained. That is, by the solid-phase oxidation of the surfaces of the semiconductor films by high-density plasma treatment which is described in this embodiment, an insulating film with a uniform thickness and low interface state density can be formed without excessive oxidation reaction at the crystal grain boundaries. 
     As the gate insulating film, only an insulating film formed by high-density plasma treatment may be used, or a stacked layer may be employed, which is obtained by deposition of an insulating film such as silicon oxide, silicon oxynitride, or silicon nitride on the insulating film, by a CVD method using plasma or thermal reaction. In either case, a transistor which includes such an insulating film formed by high-density plasma treatment in a part or the whole of its gate insulating film can have reduced characteristic variations. 
     In addition, the semiconductor films  1305   a  to  1305   f , which are obtained by irradiation of a semiconductor film with a continuous wave laser beam or a laser beam oscillated with a repetition rate of 10 MHz or more and scanning the semiconductor film with the laser beam in one direction to crystallize the semiconductor film, have a characteristic in that their crystals grow in the beam scanning direction. Transistors are each arranged so that its channel length direction (direction in which carriers move when a channel formation region is formed) is aligned with the scanning direction, and the above-described gate insulating film is combined with the semiconductor film, whereby thin film transistors (TFTs) with high electron field effect mobility and reduced variations in characteristics can be obtained. 
     Next, a first conductive film and a second conductive film are stacked over the gate insulating film  1306 . Here, the first conductive film is formed to a thickness of 20 to 100 nm by a CVD method, a sputtering method, or the like. The second conductive film is formed to a thickness of 100 to 400 nm. The first conductive film and the second conductive film are formed of an element selected from tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium (Cr), niobium (Nb), or the like, or an alloy material or a compound material containing such an element as its main component. Alternatively, the first conductive film and the second conductive film are formed of semiconductor materials typified by polycrystalline silicon doped with an impurity element such as phosphorus. As a combination example of the first conductive film and the second conductive film, a tantalum nitride film and a tungsten film; a tungsten nitride film and a tungsten film; a molybdenum nitride film and a molybdenum film; and the like can be given. Tungsten and tantalum nitride have high heat resistance. Therefore, after forming the first conductive film and the second conductive film, thermal treatment for the purpose of heat activation can be applied thereto. In addition, in the case where a two-layer structure is not employed, but a three-layer structure is employed, it is preferable to use a stacked structure of a molybdenum film, an aluminum film, and a molybdenum film. 
     Next, a resist mask is formed by photolithography, and etching treatment is conducted to form gate electrodes and gate lines. Thus, gate electrodes  1307  are formed above the semiconductor films  1305   a  to  1305   f . Here, a stacked structure of a first conductive film  1307   a  and a second conductive film  1307   b  is shown as an example of the gate electrode  1307 . 
     Next, the semiconductor films  1305   a  to  1305   f  are doped with an n-type impurity element at low concentration, using the gate electrodes  1307  as masks by an ion doping method or an ion implantation method. Then, a resist mask is selectively formed by photolithography, and the semiconductor films  1305   c  and  1305   e  are doped with a p-type impurity element at high concentration. As an n-type impurity element, phosphorus (P), arsenic (As), or the like can be used. As a p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. Here, phosphorus (P) is used as an n-type impurity element and is selectively introduced into the semiconductor films  1305   a  to  1305   f  so as to be contained at concentrations of 1×10 15  to 1×10 19 /cm 3 . Thus, n-type impurity regions  1308  are formed. In addition, boron (B) is used as a p-type impurity element, and is selectively introduced into the semiconductor films  1305   c  and  1305   e  so as to be contained at concentrations of 1×10 19  to 1×10 20 /cm 3 . Thus, p-type impurity regions  1309  are formed (see  FIG.  17 C ). 
     Subsequently, an insulating film is formed so as to cover the gate insulating film  1306  and the gate electrodes  1307 . The insulating film is formed to have either a single layer or a stacked layer of a film containing an inorganic material such as silicon, silicon oxide, or silicon nitride, or a film containing an organic material such as an organic resin by a plasma CVD method, a sputtering method, or the like. Next, the insulating film is selectively etched by anisotropic etching mainly in the perpendicular direction, so that insulating films  1310  (also referred to as sidewalls) which are in contact with the side surfaces of the gate electrodes  1307  are formed. The insulating films  1310  are used as masks in doping for forming LDD (Lightly Doped Drain) regions. 
     Next, the semiconductor films  1305   a ,  1305   b ,  1305   d , and  1305   f  are doped with an n-type impurity element at high concentration, using resist masks formed by photolithography, the gate electrodes  1307  and the insulating films  1310  as masks. Thus, n-type impurity regions  1311  are formed. Here, phosphorus (P) is used as an n-type impurity element, and is selectively introduced into the semiconductor films  1305   a ,  1305   b ,  1305   d , and  1305   f  so as to be contained at concentrations of 1×10 19  to 1×10 20 /cm 3 . Thus, the n-type impurity regions  1311  with higher concentration of impurity than that of the impurity regions  1308  are formed. 
     Through the above steps, n-channel thin film transistors  1300   a ,  1300   b ,  1300   d , and  1300   f , and p-channel thin film transistors  1300   c  and  1300   e  are formed (see  FIG.  17 D ). 
     In the n-channel thin film transistor  1300   a , a channel formation region is formed in a region of the semiconductor film  1305   a  which overlaps with the gate electrode  1307 ; the impurity regions  1311  serving as source and drain regions are formed in regions of the semiconductor film  1305   a  which do not overlap with the gate electrode  1307  and the insulating film  1310 ; and low concentration impurity regions (LDD regions) are formed in regions of the semiconductor film  1305   a  which overlap with the insulating film  1310 , between the channel formation region and the impurity regions  1311 . Similarly, channel formation regions, low concentration impurity regions, and the impurity regions  1311  are formed in the n-channel thin film transistors  1300   b ,  1300   d , and  1300   f.    
     In the p-channel thin film transistor  1300   c , a channel formation region is formed in a region of the semiconductor film  1305   c  which overlaps with the gate electrode  1307 , and the impurity regions  1309  serving as source and drain regions are formed in regions of the semiconductor film  1305   c  which do not overlap with the gate electrode  1307 . Similarly, a channel formation region and the impurity regions  1309  are formed in the p-channel thin film transistor  1300   e . Here, although LDD regions are not formed in the p-channel thin film transistors  1300   c  and  1300   e , LDD regions may be provided in the p-channel thin film transistors or a structure without LDD regions may be applied to the n-channel thin film transistors. 
     Next, an insulating film with a single layer structure or a stacked layer structure is formed so as to cover the semiconductor films  1305   a  to  1305   f , the gate electrodes  1307 , and the like. Then, conductive films  1313  electrically connected to the impurity regions  1309  and  1311  which form the source and drain regions of the thin film transistors  1300   a  to  1300   f  are formed over the insulating film (see  FIG.  18 A ). The insulating film is formed with a single layer or a stacked layer, using an inorganic material such as silicon oxide or silicon nitride, an organic material such as polyimide, polyamide, benzocyclobutene, acrylic, or epoxy, a siloxane material, or the like by a CVD method, a sputtering method, an SOG method, a droplet discharging method, a screen printing method, or the like. In this embodiment, the insulating film is formed to have a two-layer structure, and a silicon nitride oxide film is formed as a first insulating film  1312   a  and a silicon oxynitride film is fainted as a second insulating film  1312   b . In addition, the conductive films  1313  can form the source and drain electrodes of the thin film transistors  1300   a  to  1300   f.    
     Before the insulating films  1312   a  and  1312   b  are formed or after one or both of the insulating films  1312   a  and  1312   b  is/are formed, heat treatment is preferably conducted for recovery of the crystallinity of the semiconductor films, activation of the impurity element which has been added into the semiconductor films, or hydrogenation of the semiconductor films. As the heat treatment, thermal annealing, laser annealing, RTA, or the like may be applied. 
     The conductive films  1313  are formed with a single layer or a stacked layer of an element selected from aluminum (Al), tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), nickel (Ni), platinum (Pt), copper (Cu), gold (Au), silver (Ag), manganese (Mn), neodymium (Nd), carbon (C), and silicon (Si), or an alloy material or a compound material containing the element as its main component by a CVD method, a sputtering method or the like. An alloy material containing aluminum as its main component corresponds to, for example, a material which contains aluminum as its main component and also contains nickel, or a material which contains aluminum as its main component, and also contains nickel and one or both of carbon and silicon. The conductive films  1313  are preferably formed to have a stacked structure of a barrier film, an aluminum-silicon (Al—Si) film, and a barrier film or a stacked structure of a barrier film, an aluminum silicon (Al—Si) film, a titanium nitride film, and a barrier film. Note that the “barrier film” corresponds to a thin film formed of titanium, titanium nitride, molybdenum, or molybdenum nitride. Aluminum and aluminum silicon are suitable materials for forming the conductive films  1313  because they have low resistance value and are inexpensive. When barrier layers are provided as the top layer and the bottom layer, generation of hillocks of aluminum or aluminum silicon can be prevented. In addition, when a barrier film formed of titanium which is an element having a high reducing property is formed, even when there is a thin natural oxide film formed on the crystalline semiconductor film, the natural oxide film can be chemically reduced, and a favorable contact between the conductive film  1313  and the crystalline semiconductor film can be obtained. 
     Next, an insulating film  1314  is formed so as to cover the conductive films  1313 , and conductive films  1315   a  and  1315   b  electrically connected to the conductive films  1313  which form the source electrodes or the drain electrodes of the thin film transistors  1300   a  and  1300   f  are formed over the insulating film  1314 . In addition, a conductive film  1316  electrically connected to the conductive film  1313  which forms the source electrode or drain electrode of the thin film transistor  1300   b  is formed. It is to be noted that the conductive films  1315   a  and  1315   b  and the conductive film  1316  may be formed using the same material at the same time. The conductive films  1315   a  and  1315   b  and the conductive film  1316  can be formed using any of the above-described materials for the conductive film  1313 . 
     Next, a conductive film  1317  functioning as an antenna is formed so as to be electrically connected to the conductive film  1316  (see  FIG.  18 B ). 
     The insulating film  1314  can be formed with a single layer or a stacked layer of an insulating film containing oxygen and/or nitrogen such as silicon oxide (SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiO x N y  where x&gt;y&gt;0), or silicon nitride oxide (SiN x O y  where x&gt;y&gt;0); a film containing carbon such as DLC (Diamond-Like Carbon); an organic material such as epoxy, polyimide, polyamide, polyvinyl phenol, benzocyclobutene, or acrylic; or a siloxane material such as a siloxane resin by a CVD method, a sputtering method or the like. It is to be noted that a siloxane material corresponds to a material having a bond of Si—O—Si. Siloxane has a skeleton structure with the bond of silicon (Si) and oxygen (O). As a substituent of siloxane, an organic group containing at least hydrogen (e.g., an alkyl group or aromatic hydrocarbon) is used. In addition, a fluoro group may be used as the substituent. Further, both a fluoro group and an organic group containing at least hydrogen may be used as the substituent. 
     The conductive film  1317  can be formed of a conductive material by a CVD method, a sputtering method, a printing method such as screen printing or gravure printing, a droplet discharging method, a dispenser method, a plating method, or the like. The conductive film  1317  is formed with a single layer or a stacked layer of an element selected from aluminum (Al), titanium (Ti), silver (Ag), copper (Cu), gold (Au), platinum (Pt), nickel (Ni), palladium (Pd), tantalum (Ta), or molybdenum (Mo), or an alloy material or a compound material containing such an element as its main component. 
     For example, when the conductive film  1317  functioning as an antenna is formed by a screen printing method, the conductive film can be provided by selective printing of a conductive paste in which conductive particles with a grain diameter of several nm to several tens of urn are dissolved or dispersed in an organic resin. The conductive particles can be at least one or more of metal particles selected from silver (Ag), gold (Au), copper (Cu), nickel (Ni), platinum (Pt), palladium (Pd), tantalum (Ta), molybdenum (Mo), titanium (Ti), and the like; fine particles of silver halide; and dispersive nanoparticles of such an element. In addition, the organic resin included in the conductive paste can be one or more of organic resins which function as a binder, a solvent, a dispersing agent, and a coating material of the metal particles. Typically, an organic resin such as an epoxy resin and a silicone resin can be given as examples. Preferably, a conductive paste is applied and baked to form the conductive film. For example, in the case of using fine particles (e.g., a grain diameter of 1 to 100 nm) containing silver as its main component as a material of the conductive paste, the conductive paste is baked and hardened at temperatures of 150 to 300° C., so that the conductive film can be obtained. Alternatively, it is also possible to use fine particles containing solder or lead-free solder as its main component. In that case, fine particles with a grain diameter of less than or equal to 20 μm are preferably used. Solder and lead-free solder have the advantage of low cost. 
     The conductive films  1315   a  and  1315   b  can function as wirings which are electrically connected to a secondary battery included in the radio field intensity measurement device of the present invention in a later step. In addition, in forming the conductive film  1317  which functions as an antenna, other conductive films may be separately formed so as to be electrically connected to the conductive films  1315   a  and  1315   b , so that the conductive films can be utilized as the wirings to connect the conductive films  1315   a  and  1315   b  to the secondary battery. 
     Next, after forming an insulating film  1318  so as to cover the conductive film  1317 , a layer including the thin film transistors  1300   a  to  1300   f , the conductive film  1317 , and the like (hereinafter referred to as an “element formation layer  1319 ”) is peeled off the substrate  1301 . Here, after forming opening portions in the element formation layer  1319  excluding the region of the thin film transistors  1300   a  to  1300   f  by laser irradiation (e.g., UV light) (see  FIG.  18 C ), the element formation layer  1319  can be peeled off the substrate  1301  with a physical force. The peeling layer  1303  may be selectively removed by introduction of an etchant into the opening portions before peeling the element formation layer  1319  off the substrate  1301 . As the etchant, a gas or a liquid containing halogen fluoride or an interhalogen compound is used. For example, when chlorine trifluoride (ClF 3 ) is used as the gas containing halogen fluoride, the element formation layer  1319  is peeled off the substrate  1301 . The whole peeling layer  1303  is not removed but part thereof may be left. Accordingly, the consumption of the etchant can be suppressed and process time for removing the peeling layer can be shortened. In addition, even after removing the peeling layer  1303 , the element formation layer  1319  can be held above the substrate  1301 . In addition, by reuse of the substrate  1301  from which the element formation layer  1319  has been peeled, cost reduction can be achieved. 
     The insulating film  1318  can be formed with a single layer or a stacked layer of an insulating film containing oxygen and/or nitrogen such as silicon oxide (SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiO x N y  where x&gt;y&gt;0), or silicon nitride oxide (SiN x O y  where x&gt;y&gt;0); a film containing carbon such as DLC (Diamond-Like Carbon); an organic material such as epoxy, polyimide, polyamide, polyvinyl phenol, benzocyclobutene, or acrylic; or a siloxane material such as a siloxane resin by a CVD method, a sputtering method, or the like. 
     In this embodiment, after forming the opening portions in the element formation layer  1319  by laser irradiation, a first sheet material  1320  is attached to one surface of the element formation layer  1319  (the surface where the insulating film  1318  is exposed), and then the element formation layer  1319  is peeled off the substrate  1301  (see  FIG.  19 A ). 
     Next, a second sheet material  1321  is attached to the other surface of the element formation layer  1319  (the surface exposed by peeling), followed by one or both of heat treatment and pressurization treatment for attachment of the second sheet material  1321  (see  FIG.  19 B ). As the first sheet material  1320  and the second sheet material  1321 , a hot-melt film or the like can be used. 
     As the first sheet material  1320  and the second sheet material  1321 , a film on which antistatic treatment for preventing static electricity or the like has been applied (hereinafter referred to as an antistatic film) can be used. As examples of the antistatic film, a film in which an antistatic material is dispersed in a resin, a film to which an antistatic material is attached, and the like can be given. The film provided with an antistatic material can be a film with an antistatic material provided on one of its surfaces, or a film with an antistatic material provided on each of its surfaces. The film with an antistatic material provided on one of its surfaces may be attached to the layer so that the antistatic material is placed on the inner side of the film or the outer side of the film. The antistatic material may be provided for the entire surface of the film, or over a part of the film. As an antistatic material, a metal, indium tin oxide (ITO), or a surfactant such as an amphoteric surfactant, a cationic surfactant, or a nonionic surfactant can be used. Further, as an antistatic material, a resin material which contains a cross-linked copolymer having a carboxyl group and a quaternary ammonium base on its side chain, or the like can be used. Such a material is attached, mixed, or applied to a film, so that an antistatic film can be formed. The element formation layer is sealed using the antistatic film, so that the semiconductor elements can be protected from adverse effects such as external static electricity when dealt with as a commercial product. 
     It is to be noted that a thin-film secondary battery is connected to the conductive films  1315   a  and  1315   b , so that the battery is formed. The connection with the secondary battery may be conducted before the element formation layer  1319  is peeled off the substrate  1301  (at the stage shown in  FIG.  18 B  or  FIG.  18 C ), after the element formation layer  1319  is peeled off the substrate  1301  (at the stage shown in  FIG.  19 A ), or after the element formation layer  1319  is sealed with the first sheet material and the second sheet material (at the stage shown in  FIG.  19 B ). An example where the element formation layer  1319  and the secondary battery are formed to be connected is explained below with reference to  FIGS.  20 A and  20 B  and  FIGS.  21 A and  21 B . 
     In  FIG.  18 B , conductive films  1331   a  and  1331   b  which are electrically connected to the conductive films  1315   a  and  1315   b , respectively are formed at the same time as the conductive film  1317  which functions as an antenna. Then, the insulating film  1318  is formed so as to cover the conductive films  1317 ,  1331   a , and  1331   b , followed by formation of opening portions  1332   a  and  1332   b  so that the surfaces of the conductive films  1331   a  and  1331   b  are exposed. After that, the opening portions are formed in the element formation layer  1319  by laser irradiation, and then the first sheet material  1332  is attached to one surface of the element formation layer  1319  (the surface where the insulating film  1318  is exposed), so that the element formation layer  1319  is peeled off the substrate  1301  (see  FIG.  20 A ). 
     Next, the second sheet material  1333  is attached to the other surface of the element formation layer  1319  (the surface exposed by peeling), and the element formation layer  1319  is peeled off the first sheet material  1332 . Therefore, a material with low viscosity is used as the first sheet material  1332 . Then, conductive films  1334   a  and  1334   b  which are electrically connected to the conductive films  1331   a  and  1331   b  respectively through the opening portions  1332   a  and  1332   b  are selectively formed (see  FIG.  20 B ). 
     The conductive films  1334   a  and  1334   b  are formed of a conductive material by a CVD method, a sputtering method, a printing method such as screen printing or gravure printing, a droplet discharging method, a dispenser method, a plating method, or the like. The conductive films  1334   a  and  1334   b  are formed with a single layer or a stacked layer of an element selected from aluminum (Al), titanium (Ti), silver (Ag), copper (Cu), gold (Au), platinum (Pt), nickel (Ni), palladium (Pd), tantalum (Ta), or molybdenum (Mo), or an alloy material or a compound material containing the element as its main component. 
     Although the example shown in this embodiment is the case where the conductive films  1334   a  and  1334   b  are formed after peeling the element formation layer  1319  off the substrate  1301 , the element formation layer  1319  may be peeled off the substrate  1301  after the formation of the conductive films  1334   a  and  1334   b.    
     Next, in the case where a plurality of elements is formed over the substrate, the element formation layer  1319  is cut into elements (see  FIG.  21 A ). A laser irradiation apparatus, a dicing apparatus, a scribing apparatus, or the like can be used for the cutting. At this time, the plurality of elements formed over one substrate is separated from one another by laser irradiation. 
     Next, the separated elements are electrically connected to the secondary battery (see  FIG.  21 B ). In this embodiment, a thin-film secondary battery is used as the battery, in which a current-collecting thin film, a negative electrode active material layer, a solid electrolyte layer, a positive electrode active material layer, and a current-collecting thin film are sequentially stacked. 
     Conductive films  1336   a  and  1336   b  are formed of a conductive material by a CVD method, a sputtering method, a printing method such as screen printing or gravure printing, a droplet discharging method, a dispenser method, a plating method, or the like. The conductive films  1336   a  and  1336   b  are formed with a single layer or a stacked layer of an element selected from aluminum (Al), titanium (Ti), silver (Ag), copper (Cu), gold (Au), platinum (Pt), nickel (Ni), palladium (Pd), tantalum (Ta), and molybdenum (Mo), or an alloy material or a compound material containing such an element as its main component. The conductive material should have high adhesion to a negative electrode active material layer and also low resistance. In particular, aluminum, copper, nickel, vanadium, or the like is preferably used. 
     The structure of the thin-film secondary battery is described next. A negative electrode active material layer  1381  is formed over the conductive film  1336   a . In general, vanadium oxide (V 2 O 5 ) or the like is used. Next, a solid electrolyte layer  1382  is formed over the negative electrode active material layer  1381 . In general, lithium phosphate (Li 3 PO 4 ) or the like is used. Next, a positive electrode active material layer  1383  is formed over the solid electrolyte layer  1382 . In general, lithium manganate (LiMn 2 O 4 ) or the like is used. Lithium cobaltate (LiCoO 2 ) or lithium nickel oxide (LiNiO 2 ) may also be used. Next, a current-collecting thin film  1384  to serve as an electrode is formed over the positive electrode active material layer  1383 . The current-collecting thin film  1384  should have high adhesion to the positive electrode active material layer  1383  and also low resistance. For example, aluminum, copper, nickel, vanadium, or the like can be used. 
     Each of the above thin layers of the negative electrode active material layer  1381 , the solid electrolyte layer  1382 , the positive electrode active material layer  1383 , and the current-collecting thin film  1384  may be formed by a sputtering technique or an evaporation technique. In addition, the thickness of each layer is preferably 0.1 to 3 μm. 
     Next, an interlayer film  1385  is formed by application of a resin. The interlayer film  1385  is etched to form a contact hole. The interlayer film  1385  is not limited to a resin, and other films such as a CVD oxide film may be used as well; however, a resin is preferably used in terms of flatness. In addition, the contact hole may be formed without using etching, but using a photosensitive resin. Next, a wiring layer  1386  is formed over the interlayer film  1385  and connected to the conductive film  1336   b . Thus, an electrical connection with the thin-film secondary battery is secured. 
     Here, the conductive films  1334   a  and  1334   b  which are provided in the element formation layer  1319  are connected to the conductive films  1336   a  and  1336   b  respectively, which serve as the connection terminals of the thin film secondary battery  1389 , which has been made in advance. Here, an example is shown in which an electrical connection between the conductive films  1334   a  and  1336   a  or an electrical connection between the conductive films  1334   b  and  1336   b  is performed by pressure bonding with an adhesive material such as an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP) interposed therebetween. In this embodiment, the example is shown, in which the connection is performed using conductive particles  1338  included in an adhesive resin  1337 . Alternatively, a conductive adhesive such as a silver paste, a copper paste, or a carbon paste; solder joint; or the like can be used. 
     The structures of such transistors can be various without being limited to the specific structure shown in this embodiment. For example, a multi-gate structure having two or more gate electrodes may be employed. When a multi-gate structure is employed, a structure in which channel regions are connected in series is provided; therefore, a structure in which a plurality of transistors are connected in series is provided. When a multi-gate structure is employed, various advantages can be obtained in that off-current can be reduced; withstand voltage of the transistor can be increased, so that the reliability is increased; and even if drain-source voltage changes when the transistor operates in the saturation region, a drain-source current does not change very much, and thus flat characteristics can be obtained. In addition, a structure in which gate electrodes are formed above and below a channel may also be employed. When a structure in which gate electrodes are formed above and below a channel is employed, the channel region is enlarged and the amount of current flowing therethrough can be increased. Thus, a depletion layer can be easily formed and the subthreshold swing (S value) can be decreased. When gate electrodes are formed above and below a channel, a structure in which a plurality of transistors is connected in parallel is provided. 
     In addition, any of the following structures may be employed: a structure in which a gate electrode is formed above a channel; a structure in which a gate electrode is formed below a channel; a staggered structure; and an inversely staggered structure. Further, a structure in which a channel region is divided into a plurality of regions and the divided regions are connected in parallel or in series may be employed. In addition, a channel (or part thereof) may overlap with a source electrode or a drain electrode. However, when a structure in which a channel (or part thereof) overlaps with a source electrode or a drain electrode is employed, electric charges can be prevented from being accumulated in part of the channel and thus an unstable operation can be prevented. In addition, an LDD (Lightly Doped Drain) region may be provided. When an LDD region is provided, off-current can be reduced; the withstand voltage of the transistor can be increased, so that the reliability is increased; and even if drain-source voltage changes when the transistor operates in the saturation region, drain-source current does not change very much, and thus flat characteristics can be obtained. 
     The method of manufacturing the radio field intensity measurement device in this embodiment can be applied to any of the radio field intensity measurement devices in the other embodiments. 
     Embodiment 2 
     Embodiment 2 will describe an example of a method for manufacturing the radio field intensity measurement device described in the above embodiment modes, with reference to drawings. In this embodiment, a structure in which an antenna and a signal processing circuit of the radio field intensity measurement device are formed over the same substrate will be explained. It is to be noted that an antenna and a signal processing circuit are formed using transistors including channel formation regions formed on a single crystal substrate, together over the same single crystal substrate. When transistors formed using a single crystal substrate are used as the transistors, a radio field intensity measurement device having transistors with few characteristic variations can be formed, which is preferable. In addition, in this embodiment, an example is explained in which the thin-film secondary battery described in Embodiment 1 is used as the battery included in the signal processing circuit. 
     First, separated regions  2304  and  2306  (hereinafter simply referred to as regions  2304  and  2306 ) are formed in a semiconductor substrate  2300  (see  FIG.  22 A ). The regions  2304  and  2306  provided in the semiconductor substrate  2300  are separated from each other by an insulating film (also referred to as a field oxide film)  2302 . The example shown here is the case where a single crystal Si substrate having n-type conductivity is used as the semiconductor substrate  2300 , and a p well  2307  is formed in the region  2306  of the semiconductor substrate  2300 . 
     Any substrate can be used as the substrate  2300  as long as it is a semiconductor substrate. For example, a single crystal Si substrate having n-type or p-type conductivity, a compound semiconductor substrate (e.g., a GaAs substrate, an InP substrate, a GaN substrate, a SiC substrate, a sapphire substrate, or a ZnSe substrate), an SOI (Silicon on Insulator) substrate formed by a bonding method or a SIMOX (Separation by IMplanted OXygen) method, or the like can be used. 
     The regions  2304  and  2306  can be formed by a LOCOS (LOCal Oxidation of Silicon) method, a trench isolation method, or the like. 
     In addition, the p well  2307  formed in the region  2306  of the semiconductor substrate  2300  can be formed by selective doping of the semiconductor substrate  2300  with a p-type impurity element. As a p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. 
     In this embodiment, although the region  2304  is not doped with an impurity element because an n-type semiconductor substrate is used as the semiconductor substrate  2300 , an n well may be formed in the region  2304  by introduction of an n-type impurity element. As an n-type impurity element, phosphorus (P), arsenic (As), or the like can be used. When a p-type semiconductor substrate is used, on the other hand, the region  2304  may be doped with an n-type impurity element to form an n well, whereas the region  2306  may not be doped with an impurity element. 
     Next, insulating films  2332  and  2334  are formed so as to cover the regions  2304  and  2306 , respectively (see  FIG.  22 B ). 
     For example, surfaces of the regions  2304  and  2306  provided in the semiconductor substrate  2300  are oxidized by heat treatment, so that the insulating films  2332  and  2334  can be formed of silicon oxide films. Alternatively, the insulating films  2332  and  2334  may be formed to have a stacked structure of a silicon oxide film and a film containing oxygen and nitrogen (a silicon oxynitride film) by the steps of forming a silicon oxide film by a thermal oxidation method and then nitriding the surface of the silicon oxide film by nitridation treatment. 
     Further alternatively, the insulating films  2332  and  2334  can be formed by plasma treatment as described above. For example, the insulating films  2332  and  2334  can be formed using a silicon oxide (SiO x ) film or a silicon nitride (SiN x ) film which is obtained by application of high-density plasma oxidation or high-density plasma nitridation treatment to the surfaces of the regions  2304  and  2306  provided in the semiconductor substrate  2300 . Furthermore, after applying high-density plasma oxidation treatment to the surfaces of the regions  2304  and  2306 , high-density plasma nitridation treatment may be performed. In that case, silicon oxide films are formed on the surfaces of the regions  2304  and  2306 , and then silicon oxynitride films are formed on the silicon oxide films Thus, the insulating films  2332  and  2334  are each formed to have a stacked structure of the silicon oxide film and the silicon oxynitride film. In addition, high-density plasma oxidation or high-density nitridation treatment may be applied to the silicon oxide films after silicon oxide films are formed on the surfaces of the regions  2304  and  2306  by a thermal oxidation method. 
     The insulating films  2332  and  2334  formed over the regions  2304  and  2306  of the semiconductor substrate  2300  respectively function as the gate insulating films of transistors which are completed later. 
     Next, a conductive film is formed so as to cover the insulating films  2332  and  2334  which are formed over the regions  2304  and  2306 , respectively (see  FIG.  22 C ). Here, an example is shown in which conductive films  2336  and  2338  are sequentially stacked as the conductive film. Needless to say, the conductive film may be formed to have a single layer or a stacked structure of three or more layers. 
     As materials of the conductive films  2336  and  2338 , an element selected from tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium (Cr), niobium (Nb), or the like, or an alloy material or a compound material containing such an element as its main component can be used. Alternatively, a metal nitride film obtained by nitridation of the above element can be used. Besides, a semiconductor material typified by polycrystalline silicon doped with an impurity element such as phosphorus can be used. 
     In this case, a stacked structure is employed in which the conductive film  2336  is formed using tantalum nitride and the conductive film  2338  is formed thereover using tungsten. Alternatively, it is also possible to form the conductive film  2336  using a single-layer film or a stacked film of tungsten nitride, molybdenum nitride, and/or titanium nitride and form the conductive film  2338  using a single-layer film or a stacked film of tantalum, molybdenum, and/or titanium. 
     Next, the stacked conductive films  2336  and  2338  are selectively removed by etching, so that the conductive films  2336  and  2338  remain above part of the regions  2304  and  2306 , respectively. Thus, gate electrodes  2340  and  2342  are formed (see  FIG.  23 A ). 
     Next, a resist mask  2348  is selectively formed so as to cover the region  2304 , and the region  2306  is doped with an impurity element, using the resist mask  2348  and the gate electrode  2342  as masks, so that impurity regions are formed (see  FIG.  23 B ). As an impurity element, an n-type impurity element or a p-type impurity element is used. As an n-type impurity element, phosphorus (P), arsenic (As), or the like can be used. As a p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. Here, phosphorus (P) is used as the impurity element. 
     In  FIG.  23 B , by introduction of an impurity element, impurity regions  2352  which form source and drain regions and a channel formation region  2350  are formed in the region  2306 . 
     Next, a resist mask  2366  is selectively formed so as to cover the region  2306 , and the region  2304  is doped with an impurity element, using the resist mask  2366  and the gate electrode  2340  as masks, so that impurity regions are formed (see  FIG.  23 C ). As the impurity element, an n-type impurity element or a p-type impurity element is used. As an n-type impurity element, phosphorus (P), arsenic (As), or the like can be used. As a p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. At this time, an impurity element (e.g., boron (B)) of a conductivity type different from that of the impurity element introduced into the region  2306  in  FIG.  23 B  is used. As a result, impurity regions  2370  which form source and drain regions and a channel formation region  2368  are formed in the region  2304 . 
     Next, a second insulating film  2372  is formed so as to cover the insulating films  2332  and  2334  and the gate electrodes  2340  and  2342 . Then, wirings  2374 , which are electrically connected to the impurity regions  2352  and  2370  formed in the regions  2306  and  2304  respectively, are formed over the second insulating film  2372  (see  FIG.  24 A ). 
     The second insulating film  2372  can be formed with a single layer or a stacked layer of an insulating film containing oxygen and/or nitrogen such as silicon oxide (SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiO x N y  where x&gt;y&gt;0), or silicon nitride oxide (SiN x O y  where x&gt;y&gt;0); a film containing carbon such as DLC (Diamond-Like Carbon); an organic material such as epoxy, polyimide, polyamide, polyvinyl phenol, benzocyclobutene, or acrylic; or a siloxane material such as a siloxane resin by a CVD method, a sputtering method or the like. A siloxane material corresponds to a material having a bond of Si—O—Si. Siloxane has a skeleton structure with the bond of silicon (Si) and oxygen (O). As a substituent of siloxane, an organic group containing at least hydrogen (e.g., an alkyl group or aromatic hydrocarbon) is used. Also, a fluoro group may be used as the substituent, or both a fluoro group and an organic group containing at least hydrogen may be used. 
     The wirings  2374  are formed with a single layer or a stacked layer of an element selected from aluminum (Al), tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), nickel (Ni), platinum (Pt), copper (Cu), gold (Au), silver (Ag), manganese (Mn), neodymium (Nd), carbon (C), or silicon (Si), or an alloy material or a compound material containing such an element as its main component by a CVD method, a sputtering method or the like. An alloy material containing aluminum as its main component corresponds to, for example, a material which contains aluminum as its main component and also contains nickel, or a material which contains aluminum as its main component and also contains nickel and one or both of carbon and silicon. The wirings  2374  are preferably formed to have a stacked structure of a barrier film, an aluminum-silicon (Al—Si) film, and a barrier film or a stacked structure of a barrier film, an aluminum silicon (Al—Si) film, a titanium nitride film, and a barrier film. It is to be noted that the “barrier film” corresponds to a thin film formed of titanium, titanium nitride, molybdenum, or molybdenum nitride. Aluminum and aluminum silicon are suitable materials for forming the wirings  2374  because they have high resistance values and are inexpensive. When barrier layers are provided as the top layer and the bottom layer, generation of hillocks of aluminum or aluminum silicon can be prevented. When a barrier film formed of titanium which is an element having a high reducing property is formed, even when there is a thin natural oxide film formed on the crystalline semiconductor film, the natural oxide film can be chemically reduced, and a favorable contact between the wirings  2374  and the crystalline semiconductor film can be obtained. 
     It is to be noted that the structure of transistors of the present invention is not limited to the one shown in the drawing. For example, a transistor with an inversely staggered structure, a FinFET structure, or the like can be used. A FinFET structure is preferable because it can suppress a short channel effect which occurs along with reduction in transistor size. 
     The radio field intensity measurement device of the present invention includes a battery by which power can be stored in the signal processing circuit. As the battery, a capacitor such as an electric double layer capacitor or a thin-film secondary battery is preferably used. In this embodiment, a connection between the transistor formed in this embodiment and a thin-film secondary battery is explained. 
     In this embodiment, the secondary battery is stacked over the wiring  2374  connected to the transistor. The secondary battery has a structure in which a current-collecting thin film, a negative electrode active material layer, a solid electrolyte layer, a positive electrode active material layer, and a current-collecting thin film are sequentially stacked (see  FIG.  24 B ). Therefore, the material of the wiring  2374  which also has a function of the current-collecting thin film of the secondary battery should have high adhesion to the negative electrode active material layer and also low resistance. In particular, aluminum, copper, nickel, vanadium, or the like is preferably used. 
     Subsequently, the structure of the thin-film secondary battery is described. A negative electrode active material layer  2391  is formed over the wiring  2374 . In general, vanadium oxide (V 2 O 5 ) or the like is used. Next, a solid electrolyte layer  2392  is formed over the negative electrode active material layer  2391 . In general, lithium phosphate (Li 3 PO 4 ) or the like is used. Next, a positive electrode active material layer  2393  is formed over the solid electrolyte layer  2392 . In general, lithium manganate (LiMn 2 O 4 ) or the like is used. Lithium cobaltate (LiCoO 2 ) or lithium nickel oxide (LiNiO 2 ) may also be used. Next, a current-collecting thin film  2394  to serve as an electrode is formed over the positive electrode active material layer  2393 . The current-collecting thin film  2394  should have high adhesion to the positive electrode active material layer  2393  and also low resistance. For example, aluminum, copper, nickel, vanadium, or the like can be used. 
     Each of the above-described thin layers of the negative electrode active material layer  2391 , the solid electrolyte layer  2392 , the positive electrode active material layer  2393 , and the current-collecting thin film  2394  may be formed by a sputtering technique or an evaporation technique. In addition, the thickness of each layer is preferably 0.1 to 3 μm. 
     Next, an interlayer film  2396  is formed by application of a resin. The interlayer film  2396  is etched to form a contact hole. The interlayer film is not limited to a resin, and other films such as a CVD oxide film may also be used; however, a resin is preferably used in terms of flatness. In addition, the contact hole may be formed without etching, but using a photosensitive resin. Next, a wiring layer  2395  is formed over the interlayer film  2396  and connected to a wiring  2397 . Thus, an electrical connection between the secondary battery and the transistor is secured. 
     With the above-described structure, the radio field intensity measurement device of the present invention can have a structure in which transistors are formed on a single crystal substrate and a thin-film secondary battery is formed thereover. Thus, the radio field intensity measurement device of the present invention can achieve flexibility as well as thinning and reduction in size. 
     The method of manufacturing the radio field intensity measurement device in this embodiment can be applied to any of the radio field intensity measurement devices in the other embodiments. 
     Embodiment 3 
     An example of a method for manufacturing a radio field intensity measurement device, which is different from that described in Embodiment 2, will be explained with reference to drawings. 
     First, an insulating film is formed over a substrate  2600 . Here, a single crystal Si substrate having n-type conductivity is used as the substrate  2600 , and insulating films  2602  and  2604  are formed over the substrate  2600  (see  FIG.  25 A ). For example, silicon oxide (SiO x ) is formed as the insulating film  2602  by application of heat treatment to the substrate  2600 , and then silicon nitride (SiN x ) is formed over the insulating film  2602  by a CVD method. 
     Any substrate can be used as the substrate  2600  as long as it is a semiconductor substrate, without particular limitations. For example, a single crystal Si substrate having n-type or p-type conductivity, a compound semiconductor substrate (e.g., a GaAs substrate, an InP substrate, a GaN substrate, a SiC substrate, a sapphire substrate, or a ZnSe substrate), an SOI (Silicon on Insulator) substrate formed by a bonding method or a SIMOX (Separation by IMplanted OXygen) method, or the like can be used. 
     Alternatively, after forming the insulating film  2602 , the insulating film  2604  may be formed by nitridation of the insulating film  2602  by high-density plasma treatment. It is to be noted that the insulating film provided over the substrate  2600  may have a single-layer structure or a stacked structure of three or more layers. 
     Next, patterns of a resist mask  2606  are selectively formed over the insulating film  2604 , and selective etching is performed using the resist mask  2606  as a mask, so that recessed portions  2608  are selectively formed in the substrate  2600  (see  FIG.  25 B ). For the etching of the substrate  2600  and the insulating films  2602  and  2604 , plasma dry etching can be conducted. 
     Next, the patterns of the resist mask  2606  are removed, and then an insulating film  2610  is formed so as to fill the recessed portions  2608  formed in the substrate  2600  (see  FIG.  25 C ). 
     The insulating film  2610  is formed of an insulating material such as silicon oxide, silicon nitride, silicon oxynitride (SiO x N y , where x&gt;y&gt;0), or silicon nitride oxide (SiN x O y , where x&gt;y&gt;0) by a CVD method, a sputtering method, or the like. As the insulating film  2610 , a silicon oxide film is formed by an atmospheric pressure CVD method or a low-pressure CVD method using a TEOS (tetraethyl orthosilicate) gas. 
     Next, the surface of the substrate  2600  is exposed by grinding treatment or polishing treatment such as CMP (Chemical Mechanical Polishing). Here, by exposure of the surface of the substrate  2600 , regions  2612  and  2613  are formed between insulating films  2611  which are formed in the recessed portions  2608  of the substrate  2600 . The insulating film  2610  formed over the surface of the substrate  2600  is removed by grinding treatment or polishing treatment such as CMP, so that the insulating films  2611  are obtained. Subsequently, by selective introduction of a p-type impurity element, a p well  2615  is formed in the region  2613  of the substrate  2600  (see  FIG.  26 A ). 
     As a p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. In this case, boron (B) is introduced into the region  2613  as the impurity element. 
     Further, in this embodiment, although the region  2612  is not doped with an impurity element because an n-type semiconductor substrate is used as the substrate  2600 , an n well may be formed in the region  2612  by introduction of an n-type impurity element. As an n-type impurity element, phosphorus (P), arsenic (As), or the like can be used. 
     When a p-type semiconductor substrate is used, on the other hand, the region  2612  may be doped with an n-type impurity element to form an n well, whereas the region  2613  may not be doped with an impurity element. 
     Next, insulating films  2632  and  2634  are formed over the surfaces of the regions  2612  and  2613  in the substrate  2600 , respectively (see  FIG.  26 B ). 
     For example, surfaces of the regions  2612  and  2613  provided in the substrate  2600  are oxidized by heat treatment, so that the insulating films  2632  and  2634  of silicon oxide films can be formed. Alternatively, the insulating films  2632  and  2634  may each be formed to have a stacked structure of a silicon oxide film and a film containing oxygen and nitrogen (a silicon oxynitride film) by the steps of forming a silicon oxide film by a thermal oxidation method and then nitriding the surface of the silicon oxide film by nitridation treatment. 
     Further alternatively, the insulating films  2632  and  2634  may be formed by plasma treatment as described above. For example, the insulating films  2632  and  2634  can be formed with a silicon oxide (SiO x ) film or a silicon nitride (SiN x ) film which is obtained by application of high-density plasma oxidation or high-density nitridation treatment to the surfaces of the regions  2612  and  2613  provided in the substrate  2600 . In addition, after application of high-density plasma oxidation treatment to the surfaces of the regions  2612  and  2613 , high-density plasma nitridation treatment may be conducted. In that case, silicon oxide films are formed on the surfaces of the regions  2612  and  2613  and then silicon oxynitride films are formed on the silicon oxide films. Thus, the insulating films  2632  and  2634  are each formed to have a stacked structure of the silicon oxide film and the silicon oxynitride film. In addition, silicon oxide films are formed on the surfaces of the regions  2612  and  2613  by a thermal oxidation method, and then high-density plasma oxidation treatment or high-density plasma nitridation treatment may be performed to the silicon oxide films. 
     It is to be noted that the insulating films  2632  and  2634  formed over the regions  2612  and  2613  of the substrate  2600  respectively function as the gate insulating films of transistors which are completed later. 
     Next, a conductive film is formed so as to cover the insulating films  2632  and  2634  which are formed over the regions  2612  and  2613  provided in the substrate  2600 , respectively (see  FIG.  26 C ). In this embodiment, an example is shown where conductive films  2636  and  2638  are sequentially stacked as the conductive film. Needless to say, the conductive film may be formed to have a single layer or a stacked structure of three or more layers. 
     As a material of the conductive films  2636  and  2638 , an element selected from tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium (Cr), niobium (Nb), or the like, or an alloy material or a compound material containing such an element as its main component can be used. Alternatively, a metal nitride film obtained by nitridation of such an element can also be used. Furthermore, a semiconductor material typified by polycrystalline silicon doped with an impurity element such as phosphorus can also be used. 
     In this case, a stacked structure is employed in which the conductive film  2636  is formed using tantalum nitride and the conductive film  2638  is formed thereover using tungsten. Alternatively, it is also possible to form the conductive film  2636  using a single-layer film or a stacked film of tantalum nitride, tungsten nitride, molybdenum nitride, and/or titanium nitride and form the conductive film  2638  using a single-layer film or a stacked film of tungsten, tantalum, molybdenum, and/or titanium. 
     Next, the stacked conductive films  2636  and  2638  are selectively removed by etching, so that the conductive films  2636  and  2638  remain above part of the regions  2612  and  2613  of the substrate  2600 . Thus, conductive films  2640  and  2642  functioning as gate electrodes are formed (see  FIG.  27 A ). Here, surfaces of the regions  2612  and  2613  of the substrate  2600  which does not overlap with the conductive films  2640  and  2642  respectively are exposed. 
     Specifically, in the region  2612  of the substrate  2600 , a part of the insulating film  2632  formed below the conductive film  2640 , which does not overlap with the conductive film  2640 , is selectively removed, so that the ends of the conductive film  2640  and the ends of the insulating film  2632  are almost aligned with each other. In addition, in the region  2613  of the substrate  2600 , a part of the insulating film  2634  formed below the conductive film  2642 , which do not overlap with the conductive film  2642 , is selectively removed, so that the ends of the conductive film  2642  and the ends of the insulating film  2634  are almost aligned with each other. 
     In this case, the part of the insulating films or the like which do not overlap with the conductive films  2640  and  2642  may be removed at the same time as the formation of the conductive films  2640  and  2642 . Alternatively, the part of the insulating films which do not overlap with the conductive films  2640  and  2642  may be removed using resist masks which are left after the formation of the conductive films  2640  and  2642  or the conductive films  2640  and  2642  as masks. 
     Then, the regions  2612  and  2613  of the substrate  2600  are selectively doped with an impurity element (see  FIG.  27 B ). At this time, the region  2613  is selectively doped with an n-type impurity element at low concentration, using the conductive film  2642  as a mask, whereas the region  2612  is selectively doped with a p-type impurity element at low concentration, using the conductive film  2640  as a mask. As an n-type impurity element, phosphorus (P), arsenic (As), or the like can be used. As a p-type impurity element, boron (B), aluminum (Al), gallium (Ga), or the like can be used. 
     Next, sidewalls  2654  which are in contact with the side surfaces of the conductive films  2640  and  2642  are formed. Specifically, the sidewalls are formed with a single layer or a stacked layer of a film containing an inorganic material such as silicon, silicon oxide, or silicon nitride, or a film containing an organic material such as an organic resin. Then, such an insulating film is selectively etched by anisotropic etching mainly in the perpendicular direction, so that the sidewalls  2654  can be formed so as to be in contact with the side surfaces of the conductive films  2640  and  2642 . The sidewalls  2654  are used as masks in doping for forming LDD (Lightly Doped Drain) regions. In addition, the sidewalls  2654  are formed to be in contact with side surfaces of the insulating films formed below the conductive films  2640  and  2642 . 
     Next, the regions  2612  and  2613  of the substrate  2600  are doped with an impurity element, using the sidewalls  2654  and the conductive films  2640  and  2642  as masks, so that impurity regions which function as source and drain regions are formed (see  FIG.  27 C ). At this time, the region  2613  of the substrate  2600  is doped with an n-type impurity element at high concentration, using the sidewalls  2654  and the conductive film  2642  as masks, whereas the region  2612  is doped with a p-type impurity element at high concentration, using the sidewalls  2654  and the conductive film  2640  as masks. 
     As a result, impurity regions  2658  which form source and drain regions, low concentration impurity regions  2660  which form LDD regions, and a channel formation region  2656  are formed in the region  2612  of the substrate  2600 . Meanwhile, impurity regions  2664  which form source and drain regions, low concentration impurity regions  2666  which form LDD regions, and a channel formation region  2662  are formed in the region  2613  of the substrate  2600 . 
     In this embodiment, the impurity elements are introduced under the condition that parts of the regions  2612  and  2613  of the substrate  2600  which do not overlap with the conductive films  2640  and  2642  are exposed. Accordingly, the channel formation regions  2656  and  2662  which are formed in the regions  2612  and  2613  of the substrate  2600  respectively can be formed in a self-aligned manner, due to the conductive films  2640  and  2642 . 
     Next, a second insulating film  2677  is formed so as to cover the insulating films, the conductive films, and the like which are provided over the regions  2612  and  2613  of the substrate  2600 , and opening portions  2678  are formed in the second insulating film  2677  (see  FIG.  28 A ). 
     The second insulating film  2677  can be formed with a single layer or a stacked layer of an insulating film containing oxygen and/or nitrogen such as silicon oxide (SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiO x N y  where x&gt;y&gt;0), or silicon nitride oxide (SiN x O y  where x&gt;y&gt;0); a film containing carbon such as DLC 
     (Diamond-Like Carbon); an organic material such as epoxy, polyimide, polyamide, polyvinyl phenol, benzocyclobutene, or acrylic; or a siloxane material such as a siloxane resin, by a CVD method, a sputtering method or the like. A siloxane material corresponds to a material having a bond of Si—O—Si. Siloxane has a skeleton structure with the bond of silicon (Si) and oxygen (O). As a substituent of siloxane, an organic group containing at least hydrogen (e.g., an alkyl group or aromatic hydrocarbon) is used. In addition, a fluoro group may be used as the substituent. Further, a fluoro group and an organic group containing at least hydrogen may be used as the substituent. 
     Next, conductive films  2680  are formed in the opening portions  2678  by a CVD method. Then, conductive films  2682   a  to  2682   d  are selectively formed over the insulating film  2677  so as to be electrically connected to the conductive films  2680  (see  FIG.  28 B ). 
     The conductive films  2680  and  2682   a  to  2682   d  are formed with a single layer or a stacked layer of an element selected from aluminum (Al), tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), nickel (Ni), platinum (Pt), copper (Cu), gold (Au), silver (Ag), manganese (Mn), neodymium (Nd), carbon (C), or silicon (Si), or an alloy material or a compound material containing such an element as its main component by a CVD method, a sputtering method or the like. An alloy material containing aluminum as its main component corresponds to, for example, a material which contains aluminum as its main component and also contains nickel, or a material which contains aluminum as its main component and also contains nickel and one or both of carbon and silicon. For example, each of the conductive films  2680  and  2682   a  to  2682   d  is preferably formed to have a stacked structure of a barrier film, an aluminum-silicon (Al—Si) film, and a barrier film or a stacked structure of a barrier film, an aluminum silicon (Al—Si) film, a titanium nitride film, and a barrier film. It is to be noted that the “barrier film” corresponds to a thin film formed of titanium, titanium nitride, molybdenum, or molybdenum nitride. Aluminum and aluminum silicon are suitable materials for forming the conductive films  2680  and  2682   a  to  2682   d  because they have high resistance values and are inexpensive. When barrier layers are provided as the top layer and the bottom layer, generation of hillocks of aluminum or aluminum silicon can be prevented. When a barrier film formed of titanium which is an element having a high reducing property is formed, even when there is a thin natural oxide film formed on the crystalline semiconductor film, the natural oxide film can be chemically reduced, and a favorable contact between the conductive film  2680  and  2682   a  to  2682   d , and the crystalline semiconductor film can be obtained. Here, the conductive films  2680  and  2682   a  to  2682   d  can be formed by selective growth of tungsten (W) by a CVD method. 
     Through the above steps, a p-channel transistor formed in the region  2612  of the substrate  2600  and an n-channel transistor formed in the region  2613  of the substrate  2600  can be obtained. 
     It is to be noted that the structure of transistors constituting the radio field intensity measurement device of the present invention is not limited to the one shown in the drawings. For example, a transistor with an inversely staggered structure, a FinFET structure, or the like can be used. A FinFET structure is preferable because it can suppress a short channel effect which occurs along with reduction in transistor size. 
     The radio field intensity measurement device of the present invention is provided with a battery by which power can be stored in the signal processing circuit. As the battery, a capacitor such as an electric double layer capacitor or a thin-film secondary battery is preferably used. In this embodiment, a connection between the transistor formed in this embodiment and a thin-film secondary battery will be described. 
     In this embodiment, a secondary battery is stacked over the conductive film  2682   d  connected to the transistor. The secondary battery has a structure in which a current-collecting thin film, a negative electrode active material layer, a solid electrolyte layer, a positive electrode active material layer, and a current-collecting thin film are sequentially stacked (see  FIG.  28 B ). Therefore, the material of the conductive film  2682   d  which is also used as the material of the current-collecting thin film of the secondary battery preferably has high adhesion to the negative electrode active material layer and also low resistance. In particular, aluminum, copper, nickel, vanadium, or the like is preferably used. 
     Subsequently, the structure of the thin-film secondary battery is described. A negative electrode active material layer  2691  is formed over the conductive film  2682   d . In general, vanadium oxide (V 2 O 5 ) or the like is used. Next, a solid electrolyte layer  2692  is formed over the negative electrode active material layer  2691 . In general, lithium phosphate (Li 3 PO 4 ) or the like is used. Next, a positive electrode active material layer  2693  is formed over the solid electrolyte layer  2692 . In general, lithium manganate (LiMn 2 O 4 ) or the like is used. Lithium cobaltate (LiCoO 2 ) or lithium nickel oxide (LiNiO 2 ) can also be used. Next, a current-collecting thin film  2694  to serve as an electrode is formed over the positive electrode active material layer  2693 . 
     The current-collecting thin film  2694  should have high adhesion to the positive electrode active material layer  2693  and also low resistance. For example, aluminum, copper, nickel, vanadium, or the like can be used. 
     Each of the above-described thin layers of the negative electrode active material layer  2691 , the solid electrolyte layer  2692 , the positive electrode active material layer  2693 , and the current-collecting thin film  2694  may be formed by a sputtering technique or an evaporation technique. In addition, the thickness of each layer is preferably 0.1 to 3 μm. 
     Next, an interlayer film  2696  is formed by application of a resin. The interlayer film  2696  is etched to form a contact hole. The interlayer film  2696  is not limited to a resin, and other films such as a CVD oxide film may also be used; however, a resin is preferably used in terms of flatness. In addition, the contact hole may be formed without etching, but using a photosensitive resin. Next, a wiring layer  2695  is formed over the interlayer film  2696  and is connected to a wiring  2697 . Thus, an electrical connection between the thin-film secondary battery and the transistor is obtained by the connection with the wiring  2697 . 
     With the above-described structure, the radio field intensity measurement device of the present invention can have a structure in which transistors are formed on a single crystal substrate and a thin-film secondary battery is formed thereover. Thus, the radio field intensity measurement device of the present invention can achieve flexibility as well as thinning and reduction in size. 
     The method of manufacturing the radio field intensity measurement device in this embodiment can be applied to any of the radio field intensity measurement devices in the other embodiments. 
     Embodiment 4 
     Embodiment 4 will describe applications of the radio field intensity measurement device of the present invention. The radio field intensity measurement device of the present invention can protect an object which may malfunction due to a radiowave of medical equipment, pace makers or the like, and can visibly informs us that the intensity of the radiowave around the object is high. Thus the radio field intensity measurement device of the present invention can be used as a so-called radio field intensity detector. 
     In this embodiment, with reference to  FIGS.  29 A to  36 B , application examples of the present invention and examples of products in the application examples are described. 
       FIG.  29 A  illustrates an example of a completed radio field intensity detector according the present invention. A radio field intensity measurement device  3001  is formed on a checking badge  3000 . On the checking badge  3000 , an ID  3002  and a photograph  3003  of an operator wearing the checking badge is attached. The checking badge  3000  like this, as illustrated in  FIG.  29 B , is attached on work clothes  3004  of the operator. The operator has the radio field intensity detector and confirms color changed of the radio field intensity measurement device  3001 , when the operator enters an area with extremely intense radiowave. At this time, the operator can know the intensity of radiowave. The radio field intensity measurement device of the present invention can measure a weak radiowave from a long distance, and has excellent visibility even when brightness in surroundings is intense e.g., under sunlight. Therefore, in the radio field intensity detector of  FIG.  29 A , the operator can measure a weak radiowave from a long distance and can see the measured result with excellent visibility even when brightness in surroundings is intense e.g., under sunlight. 
       FIG.  30 A  illustrates an example of a completed radio field intensity detector according to the present invention. On a seal  3100 , a warning mark  3101  to warn someone not to use a device sending a radiowave and a radio field intensity measurement device  3102  are formed. The seal  3100  like this is attached to a medical device  3103  in a hospital as illustrated in  FIG.  30 B  for example. When a visitor or a hospital patient comes near the radio field intensity measurement device  3102 , having a device sending a radiowave whose power is not switched off, the color of the radio field intensity measurement device  3102  is changed to send a visible warning and tell the visitor or the hospital patient to switch off the device sending radiowave. The radio field intensity measurement device of the present invention can measure a weak radiowave from a long distance, and has excellent visibility even when brightness in surroundings is intense e.g., under sunlight. Therefore, in the radio field intensity detector of  FIG.  30 A , a visitor or a hospital patient can measure a weak radiowave from a long distance and can see the measured result with excellent visibility even when brightness in surroundings is intense e.g., under sunlight. 
       FIG.  31 A  illustrates an example of a completed radio field intensity detector according to the present invention. On a seal  3200 , a warning mark  3201  to warn someone not to use a cellular phone and a radio field intensity measurement device  3202  are formed. The seal  3200  like this is attached to a strap  3203  near priority seating in a train as illustrated in  FIG.  31 B  for example. When a passenger has a cellular phone whose power is not switched off and an antenna  3205  of the cellular phone  3204  sends radiowave, the color of the radio field intensity measurement device  3202  is changed due to a radiowave to visibly warn the passenger to switch off the cellular phone. In addition, someone has or wear an object which may malfunction due to radiowave, such as a pace maker, he/she can sense a risk of the malfunction by seeing the color of the radio field intensity measurement device, and he/she can leave the source of radiowave. The radio field intensity measurement device of the present invention can measure a weak radiowave from a long distance, and has excellent visibility even when brightness in surroundings is intense e.g., under sunlight. Therefore, in the radio field intensity detector of  FIG.  31 A , a passenger can measure a weak radiowave from a long distance and can see the measured result with excellent visibility even when brightness in surroundings is intense e.g., under sunlight. 
       FIG.  32 A  illustrates an example of a completed radio field intensity detector according to the present invention. On a warning light  3300 , a warning mark  3301  incorporating the radio field intensity measurement device of the present invention is formed. The warning light like this is used in an airplane  3302  as illustrated in  FIG.  32 B  for example. Specifically, as illustrated in  FIG.  32 C , the warning light  3300  is installed above seats  3303 . When an airplane takes off, a flight attendant confirms the warning light. If a source emitting a radiowave is around, the flight attendant warns passengers to switch off the source. The radio field intensity measurement device of the present invention can measure a weak radiowave from a long distance, and has excellent visibility even when brightness in surroundings is intense e.g., under sunlight. Therefore, in the radio field intensity detector of  FIG.  32 A , a flight attendant can measure a weak radiowave from a long distance and can see the measured result with excellent visibility even when brightness in surroundings is intense e.g., under sunlight, so that the radio field intensity detector works as a security device in the public vehicle. 
       FIG.  33 A  illustrates an example of a completed radio field intensity detector according to the present invention. On a warning light  3400 , a warning mark  3401  incorporating the radio field intensity measurement device of the present invention is formed. The warning light like this is incorporated in an electromagnetic cooker (or an induction heating (IH) cooker)  3402  as illustrated in  FIG.  33 B  for example. When the electromagnetic cooker is broken and emits dangerous electromagnetic wave around, the color of the warning light is changed to notify danger. The radio field intensity measurement device of the present invention can measure a weak radiowave from a long distance, and has excellent visibility even when brightness in surroundings is intense e.g., under sunlight. Therefore, in the radio field intensity detector of  FIG.  33 A , a user can measure a weak radiowave from a long distance and can see the measured result with excellent visibility even when brightness in surroundings is intense e.g., under sunlight. 
       FIG.  34 A  illustrates an example of a completed radio field intensity detector according to the present invention. On a display portion  3405 , a warning mark  3406  incorporating the radio field intensity measurement device of the present invention is formed. The display portion like this is incorporated in a microwave oven  3407  as illustrated in  FIG.  34 B  for example. When the microwave oven  3407  is broken and emits dangerous electromagnetic wave around, the color of the warning light is changed to notify danger. The radio field intensity measurement device of the present invention can measure a weak radiowave from a long distance, and has excellent visibility even when brightness in surroundings is intense e.g., under sunlight. Therefore, in the radio field intensity detector of  FIG.  34 A , a user can measure a weak radiowave from a long distance and can see the measured result with excellent visibility even when brightness in surroundings is intense e.g., under sunlight. 
       FIG.  35 A  is an example of a completed radio field intensity detector according to the present invention. On a seal  3500 , a radio field intensity measurement device  3501  is formed. The seal  3500  like this is attached on a computer  3502  as illustrated in  FIG.  35 B  for example. A user of the computer can know the intensity of a radiowave used in radio communication by the color change of the radio field intensity measurement device  3501 . The radio field intensity measurement device of the present invention can measure a weak radiowave from a long distance, and has excellent visibility even when brightness in surroundings is intense e.g., under sunlight. Therefore, in the radio field intensity detector of  FIG.  35 A , a user can measure a weak radiowave from a long distance and can see the measured result with excellent visibility even when brightness in surroundings is intense e.g., under sunlight. 
       FIG.  36 A  illustrates an example of a completed radio field intensity detector according to the present invention. On a plate  3600 , a radio field intensity measurement device  3601  is formed. The plate  3600  like this is attached on an inner wall of a radiowave measurement room  3602  as illustrated in  FIG.  36 B . A design engineer of an antenna sends a radiowave by using the computer  3603  through an antenna  3604 , and confirms the color change of the inner wall of the radiowave measurement room. Thus, the distribution of the radiowave is observed in a visible manner and the performance of the antenna  3604  can be measured. The radio field intensity measurement device of the present invention can measure a weak radiowave from a long distance, and has excellent visibility even when brightness in surroundings is intense e.g., under sunlight. Therefore, in the radio field intensity detector of FIG. 36A, a user can measure a weak radiowave from a long distance and can see the measured result with excellent visibility even when brightness in surroundings is intense e.g., under sunlight. 
     As described above, the radio field intensity measurement device of the present invention can be provided in any object (including creatures) of which the level of radiowave is to be detected. 
     This embodiment can be freely combined with any of the other embodiment modes and embodiments. In other words, a radio field intensity detector including the radio field intensity measurement device of the preset invention can measure a weak radiowave from a long distance, and can have excellent visibility even when brightness in surroundings is intense e.g., under sunlight. 
     Embodiment 5 
     Embodiment 5 will describe application of a radio field intensity detector of the present invention. The radio field intensity detector using the radio field intensity measurement device of the present invention can be used as an amusement device utilizing a radiowave as colors. 
     In this embodiment, application examples of the present invention and examples of products in the application examples are described with reference to  FIGS.  37 A and  37 B . 
       FIG.  37 A  illustrates an example of a completed radio field intensity detector according to the present invention. On a plate  3700 , a radio field intensity measurement device  3701  is formed. A thin plastic plate is used as the plate  3700 , and transistors forming the radio field intensity measurement device is formed on the thin plastic substrate, so that it can be processed to be curved. 
     In the game console of this embodiment, a plurality of the plates  3700  in  FIG.  37 A  are combined to form a plate-like radio field intensity detector  3710  having a height as high as a man, as illustrated in  FIG.  37 B . A user  3702  sends a radiowave by swinging around a stick  3704  including a radiowave emitter  3703 , and enjoys color change of the plate-like radio field intensity detector  3710 . 
     Sending of a radiowave by the user is interlocked with the movement of the user  3702  by combining a sensor such as an acceleration sensor or a piezoelectric sensor including a microphone or the like incorporated in the stick  3704  to entertain the amusement device more. In addition, in  FIG.  37 B , the stick  3704  is illustrated as a member including a radiowave emitter; however, is not limited to a stick shape, and the member including a radiowave emitter may be operative by interlocking with the movement of human body. 
     This embodiment employs a flat plate-like shape for the plate-like radio field intensity detector  3710 ; however, may another shape such as sphere or irregular surface to enjoy the color change. Further, by combining a liquid crystal display device or a light-emitting device, an amusement device having wide visible variation may be formed. 
     As described above, a radio field intensity measurement device of the present invention can be provided in any object (including creatures) of which the level of the radiowave is to be detected. 
     This embodiment can be freely combined with any of the other embodiment modes and embodiments. In other words, a radio field intensity detector including the radio field intensity measurement device of the preset invention can measure a weak radiowave from a long distance, and can have excellent visibility even when brightness in surroundings is intense e.g., under sunlight. 
     This application is based on Japanese Patent Application serial No. 2006-309996 filed in Japan Patent Office on Nov. 16, 2006, the entire contents of which are hereby incorporated by reference.