Manufacturing method of semiconductor device

It is an object of the present invention to provide a manufacturing method of a semiconductor device where a semiconductor element is prevented from being damaged and throughput speed thereof is improved, even in a case of thinning or removing a supporting substrate after forming the semiconductor element over the supporting substrate. According to one feature of the present invention, a method for manufacturing a semiconductor device includes the steps of forming a plurality of element groups over an upper surface of a substrate; forming an insulating film so as to cover the plurality of element groups; selectively forming an opening to the insulating film which is located in a region between neighboring two element groups in the plurality of element groups to expose the substrate; forming a first film so as to cover the insulating film and the opening; exposing the element groups by removing the substrate; forming a second film so as to cover the surface of the exposed element groups; and cutting off between the plurality of element groups so as not to expose the insulating film.

TECHNICAL FIELD

The present invention relates to a manufacturing method of a semiconductor device, in particular, to a manufacturing method of a semiconductor device where a supporting substrate is removed after forming a semiconductor element such as transistor over the supporting substrate.

BACKGROUND ART

In recent years, by forming a semiconductor element over a rigid substrate such as a glass substrate, a semiconductor device has been actively developed for use in a display such as an LCD or an organic EL display, a photoelectric conversion element such as a photo sensor or a solar cell, or the like. Besides, a semiconductor device which transmits and receives data without contact (also referred to as an RFID (Radio Frequency Identification) tag, an ID tag, an IC tag, an IC chip, a wireless tag, an electronic tag, or a wireless chip) has been actively developed. In addition, recently, a flexible device such as a film-state display or a semiconductor device embedded in paper has been required, and a reduction in thickness holds an important clue.

In order to reduce thickness of a semiconductor device, there is a method for using a substrate which is thinned in advance, for example. However, in this case, warpage or the like of the substrate, or, in dealing with the element, warpage due to stress, difficulty in handling, misalignment in lithography or a printing step, and the like become problems. Therefore, a method for thinning or removing a substrate after forming a semiconductor element over the substrate is generally used.

As a method for thinning or removing a substrate, for example, there is a technique for removing a supporting substrate (a glass substrate) by grinding treatment or polishing treatment, or wet etching using a chemical reaction (for example, see Reference 1: Japanese Published Patent Application No. 2002-87844).

DISCLOSURE OF INVENTION

However, in a case of removing a substrate, over which a semiconductor element is formed, by grinding treatment or polishing treatment, there is a limit of thinning a film due to a limit of accuracy of a device and in-plane uniformity of polishing; therefore, it has been difficult to make the entire surface have thickness of 50 μm or less; thus, it has been difficult to remove the substrate. In addition, when a substrate is subjected to grinding treatment and polishing treatment, a semiconductor element provided over the substrate is stressed, thereby having fear of damaging the semiconductor element. This is because the semiconductor element is stressed more significantly as the substrate becomes thinner; therefore, it has been difficult to remove the substrate by grinding treatment or polishing treatment.

In addition, in a case of removing the substrate, over which the semiconductor element is formed, by chemical treatment, it is extremely difficult to remove only the substrate with high yields and uniformly; thus, there has been a problem that it takes up much time to perform the treatment.

In view of the above problems, it is an object of the present invention to provide a manufacturing method of a semiconductor device where a semiconductor element is prevented from being damaged and throughput speed thereof is improved, even in a case of thinning or removing a supporting substrate after forming the semiconductor element over the supporting substrate.

According to one feature of the present invention, a method for manufacturing a semiconductor device includes the steps of forming a plurality of element groups over an upper surface of a substrate; forming an insulating film so as to cover the plurality of element groups; selectively forming an opening to the insulating film which is located in a region between neighboring two element groups in the plurality of element groups to expose the substrate; forming a first film so as to cover the insulating film and the opening; exposing the element groups by removing the substrate; forming a second film so as to cover the surface of the exposed element groups; and cutting off between the plurality of element groups so as not to expose the insulating film.

According to another feature of the present invention, a method for manufacturing a semiconductor device includes the steps of forming a base film over an upper surface of a substrate; forming a plurality of element groups over the base film; forming an insulating film so as to cover the plurality of element groups; selectively forming an opening to the insulating film which is located in a region between neighboring two element groups in the plurality of element groups to expose the substrate or the base film; forming a first film so as to cover the insulating film and the opening; exposing the base film by removing the substrate; forming a second film so as to cover the surface of the exposed base film; and cutting off between the plurality of element groups so as not to expose the insulating film.

According to another feature of the present invention, in a method for manufacturing a semiconductor device in the above structures, a substrate is removed by being thinned from the other side and then removing the thinned substrate by chemical treatment using chemical reaction (chemical reaction treatment (hereinafter, also simply referred to as chemical treatment)). Note that a substrate can be thinned using a physical means, or a physical means with a chemical means, and for example, either grinding treatment or polishing treatment, or both can be used. Chemical treatment can be performed by dipping a thinned substrate into a chemical solution and generating chemical reaction to the thinned substrate.

Even in a case of removing a substrate over which a semiconductor element is formed, the semiconductor element is prevented from being damaged according to the present invention. Consequently, throughput speed of a semiconductor device can be improved.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment modes of the present invention will be hereinafter explained with reference to drawings. However, the present invention is not limited to the following explanations, and it is to be easily understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications depart from the purport and the scope of the present invention, they should be construed as being included therein. Note that, in the structure of the present invention that will be hereinafter explained, the same reference numerals denoting the same portions are used in common in different drawings and the explanation is omitted in some cases.

This embodiment will explain an example of a manufacturing method of a semiconductor device of the present invention with reference to drawings.

First, an element group102is formed over a substrate101(FIG. 1A). In this embodiment mode, the element group102constituting a semiconductor device is provided in plural over the substrate101. By forming the element group102in plural over the substrate101, a plurality of semiconductor devices can be manufactured from one substrate, which is preferable.

As the substrate101, a glass substrate, a quartz substrate, a metal substrate or a stainless steel substrate where an insulating film is formed over one surface, a heat-resistant plastic substrate that can withstand a processing temperature in this process, or the like is preferably used. Such a substrate101does not have a limit in its area or shape; therefore, as long as a rectangular substrate one side of which is 1 meter or more is used as the substrate101, for example, productivity can be improved significantly. Besides, a semiconductor substrate such as a Si substrate may also be used.

The element group102includes a semiconductor element such as a transistor or a diode, for example. As the transistor, a thin film transistor (TFT) where a semiconductor film, which is formed over a rigid substrate such as glass, is used as a channel, a field effect transistor (FET) over a semiconductor substrate such as a Si substrate, where the substrate is used as a channel, an organic TFT where an organic material is used as a channel, or the like can be provided. In addition, as the diode, various diodes such as a variable capacitance diode, a Schottky diode, and a tunnel diode can be applied. In the present invention, by using these transistors, diodes, or the like, any sort of integrated circuits including a CPU, a memory, a microprocessor, various sensors such as a temperature sensor; a humidity sensor; and a biosensor, and the like can be provided. Moreover, as the element group102, the present invention includes a mode having an antenna in addition to the semiconductor element such as a transistor. A semiconductor device where the element group102is provided with an antenna can be operated by using an AC voltage that is generated in the antenna and data can be transmitted and received without contact with a piece of external equipment (a reader/writer) by modulating an AC voltage that is applied to the antenna. Note that the antenna may be formed along with an integrated circuit having a transistor or may be electrically connected to an integrated circuit after being formed separately from the integrated circuit.

Next, an insulating film103is formed so as to cover the element group102(FIG. 1B). The insulating film103is provided above a plurality of the element groups102and between the element groups, and serves as a protective film of the element group102.

The insulating film103can be provided with a single-layer structure of an insulating film containing oxygen and/or nitrogen such as a silicon oxide (SiOx) film, a silicon nitride (SiNx) film, a silicon oxynitride (SiOxNy) (X>Y) film, or a silicon nitride oxide (SiNxOy) (X>Y) film, a film containing carbon such as a DLC (diamond like carbon) film, an organic material such as epoxy, polyimide, polyamide, polyvinyl phenol, benzocyclobutene, or acrylic, or a siloxane material such as a siloxane resin; or a stacked structure thereof. Note that the siloxane material corresponds to a material having Si—O—Si bonds. Siloxane has a skeleton formed of a bond of silicon (Si) and oxygen (O). As a substituent, an organic group containing at least hydrogen (for example, an alkyl group or aromatic hydrocarbon) is used. As a substituent, a fluoro group can also be used. Alternatively, an organic group containing at least hydrogen and a fluoro group may be used as a substituent.

Then, an opening104is selectively formed in the insulating film103(FIG. 1C). The opening104is selectively formed by irradiating a portion between a plurality of the element groups102(here, a portion between the neighboring element groups102) with laser light or by using a photolithography method. Note that the opening104is formed in a portion where the element group102is avoided, and here, the opening104is linearly formed by irradiating a portion between the element groups with laser light. Thus, it is preferable that the element group102be not exposed by forming the opening104.

Next, a film105is formed so as to cover the insulating film103and the opening104(FIG. 1D). When a layer including the element group102, the insulating film103, and the film105(hereinafter, referred to as an element formation layer110) is separated from the substrate101, the element formation layer110is prevented from transforming by providing the film105. In addition, here, it is preferable to form the film105so as to fill the opening104partially or entirely.

The film105can be a film made from polypropylene, polyester, vinyl, polyvinyl fluoride, polyvinyl chloride, or the like, paper of a fibrous material, a laminated film of a base film (polyester, polyamide, an inorganic vapor-deposited film, paper, or the like) and an adhesive synthetic resin film (an acrylic-based synthetic resin, an epoxy-based synthetic resin, or the like), or the like. The film is attached to an object to be treated by being subjected to heat treatment and pressure treatment. In performing heat treatment and pressure treatment, an adhesive layer provided over the uppermost surface of the film or a layer (not an adhesive layer) provided over the outermost layer is melted by heat treatment to be attached by applying pressure. An adhesive layer may be provided over the surface of the film; however, it is not necessarily provided. The adhesive layer corresponds to a layer containing an adhesive such as a thermosetting resin, a UV curing resin, an epoxy-based resin, or a resin additive. The film used for sealing is preferably coated with silica to prevent moisture or the like from entering the inside after sealing, and for example, a sheet material in which an adhesive layer, a film of polyester or the like, and silica coat are laminated can be used. Thus, the adhesive layers of these films are provided so as to fill the opening104partially or entirely.

In addition, a hot-melt adhesive can be used as the adhesive layer. The hot-melt adhesive is formed using a nonvolatile thermoplastic material that contains no water or solution, and remains in a solid state at room temperature. The hot-melt adhesive is a chemical substance that attaches objects together by applying the chemical substance in a dissolved state and cooling it. Further, the hot-melt adhesive has advantages of short adhesion time and being pollution-free, safe, hygienic, energy-saving, and low-cost. Since the hot-melt adhesive remains in the solid state at normal temperature, the hot-melt adhesive that has been processed into a film form or a fiber form in advance can be used. Alternatively, an adhesive layer that is formed over a base film made from polyester or the like in advance and then is processed into a film form can be used. A film in which a hot-melt film is formed over a base film made from polyethylene terephthalate is used here. The hot-melt film is formed using resin with a softening point that is lower than that of the base film. By performing heat treatment, only the hot-melt film is dissolved and becomes a rubbery state so that the dissolved hot-melt film is attached to an object. When cooling the hot-melt film, it is cured. As the hot-melt film, for example, a film containing as its main component ethylene-vinyl acetate copolymer (EVA), polyester, polyamide, thermoplastic elastomer, polyolefin, or the like can be used.

Then, the substrate101is thinned by a means107for thinning a film (FIG. 2A). Here, the substrate101is thinned by thinning the substrate101on which the element group102is formed from the opposite side of the substrate101(back surface) to be a substrate106. In the case of thinning the substrate101, it is preferable to thin as much as possible to reduce the processing time in the subsequent step (etching by chemical treatment). However, the substrate101is likely to be damaged due to the stress applied to the element formation layer110as the substrate101becomes thinner. Therefore, the thickness of the substrate106is made to be 5 to 50 μm, preferably 5 to 20 μm, and much preferably 5 to 10 μm.

As the means107for thinning a film, a physical means, and a physical means with a chemical means can be used, and for example, grinding treatment, polishing treatment, or the like can be used. As for grinding treatment, an upper surface of an object to be treated (here, a back surface of the substrate101) is ground and smoothed using grains of a grinding stone. As for polishing treatment, the upper surface of the object to be treated is smoothed by a plastic smoothing action or frictional polishing action using an abrasive agent such as abrasive-coated cloth and paper or abrasive grains. In a case of performing grinding treatment or polishing treatment, purified water, polishing solution, or the like can be used. In addition, as polishing treatment, CMP (Chemical Mechanical Polishing) may also be used.

In this embodiment mode, grinding treatment is performed to the back surface of the substrate101and thereafter polishing treatment is performed to the back surface of the substrate101; therefore, the substrate101is thinned to be the substrate106. Note that one of grinding treatment and polishing treatment may be performed. In the case of performing either grinding treatment or polishing treatment, or both, it is preferable to thin the substrate101as much as possible. However, as the substrate101is thinned, the element formation layer110is likely to be stressed; thus, there is fear of being damaged due to a crack or the like.

Generally, as shown inFIGS. 4A and 4B, in a case of performing grinding treatment or polishing treatment to a substrate101after forming an insulating film103and a film105above an element group102without providing an opening104(FIG. 4A), a crack111is generated in the element group102or the insulating film103when an element formation layer110is stressed (FIG. 4B).

On the other hand, in the manufacturing method described in this embodiment mode, there is a structure where the opening104is formed between a plurality of the element groups102(here, a portion between the neighboring element groups102) at the phase before subjecting the substrate101to grinding treatment or polishing treatment. Therefore, there is an advantage that the stress applied to the element group102and the insulating film103is dispersed when the element formation layer110is stressed by grinding treatment or polishing treatment; thus, a crack is unlikely to be generated in the element group102. In addition, when the stress is generated, the damage of the element group102can be suppressed effectively, as long as the stress is selectively applied to the film105provided to the opening104. Therefore, in consideration of the material of the insulating film103and the film105covering the element group102, for example, it is preferable to form the film105with a material that is bent more easily than the element group102or the insulating film103.

The material used for the film105preferably has a property of being bent more easily than that of the element group102or the insulating film103. For example, a material exhibiting elasticity or a material having plasticity can be used. Note that, in the case of using a material exhibiting elasticity, the material used for the film105is set to have a lower elastic modulus (ratio of stress to strain) than that of a material used for the insulating film103. In the case of using a material having plasticity, the material used for the film105is set to have higher plasticity than that of a material provided in the insulating film103. Note that the elasticity here refers to a property of an object whose shape or volume is changed by external force to return to its original condition after the force is removed. In addition, the plasticity here means a property of being easily deformed by external force and kept strained even after removing the force.

In addition, in a case of using a high molecular weight organic compound or the like having a glass transition temperature as the insulating film103or the film105, the material used for the film105is set to have a lower glass transition point than that of a material used for the insulating film103. A material having a low glass transition point has higher viscoelasticity than that of a material having a high glass transition point. Therefore, in a case where the material having a low glass transition and the material having a high glass transition are provided, large strain is selectively generated in the material having a low glass transition point when stress is applied. Thus, the damage of the element group102covered with the insulating film103can be suppressed.

Next, the thinned substrate106is removed by performing chemical treatment thereto (FIG. 2B). As chemical treatment, chemical etching is performed to an object to be treated by using a chemical solution. Here, the etching of the substrate106is performed by dipping the substrate106and the element formation layer110into a chemical solution108. Any chemical solution is accepted as the chemical solution108as long as the substrate can be removed, and for example, it is preferable to use a solution containing hydrofluoric acid as the chemical solution108in a case of using a glass substrate as the substrate101. Note that, as the film105, it is preferable to use a material that is unlikely to react with the chemical solution108. In addition, a base film may be formed between the substrate101and the element group102with a material that is unlikely to react with the chemical solution108. In a case of using a glass substrate as the substrate101and removing the glass substrate by being dipped into hydrofluoric acid, it is preferable to provide the base film with nitride, and for example, a single-layer structure of an insulating film containing nitrogen such as a silicon nitride (SiNx) film, a silicon oxynitride (SiOxNy) (X>Y) film, or a silicon nitride oxide (SiNxOy) (X>Y) film; or a stacked structure thereof.

Note that, in the above steps, the substrate101may be removed by grinding treatment, polishing treatment, or the like. However, in a case of performing grinding treatment or polishing treatment with a state where the substrate101is thinned, it is difficult to obtain a uniform thin film and probability that the damage due to the generation of stress applied to the element formation layer110is increased. On the other hand, the substrate101may be removed by using chemical treatment without grinding treatment and polishing treatment; however, in this case, there is fear that it takes up much time to remove the substrate101and throughput speed is decreased. Moreover, there is fear that the element formation layer110has a harmful effect by dipping the element formation layer in the chemical solution for a long time.

Therefore, in the present invention, after once performing grinding treatment, polishing treatment, or the like and thinning the substrate101to some extent when the substrate is removed, the thinned substrate is removed using chemical treatment. Thus, stress or the like applied to the element formation layer can be suppressed, and throughput speed can be improved.

Then, a film109is formed over one surface of the element formation layer110(a surface where the substrate101is removed) to perform sealing treatment to the element formation layer110(FIG. 2C).

The film109can be a film made from polypropylene, polyester, vinyl, polyvinyl fluoride, polyvinyl chloride, or the like, paper of a fibrous material, a laminated film of a base film (polyester, polyamide, an inorganic vapor-deposited film, paper, or the like) and an adhesive synthetic resin film (an acrylic-based synthetic resin, an epoxy-based synthetic resin, or the like), or the like. The film is attached to an object to be treated by being subjected to heat treatment and pressure treatment. In performing heat treatment and pressure treatment, an adhesive layer provided over the uppermost surface of the film or a layer (not an adhesive layer) provided over the outermost layer is melted by heat treatment to be attached by applying pressure. An adhesive layer may be provided over the surface of the film; however, it is not necessarily provided. The adhesive layer corresponds to a layer containing an adhesive such as a thermosetting resin, a UV curing resin, an epoxy-based resin, or a resin additive. The film used for sealing is preferably coated with silica to prevent moisture or the like from entering the inside after sealing, and for example, a sheet material in which an adhesive layer, a film of polyester or the like, and silica coat are laminated can be used.

In addition, a hot-melt adhesive can be used as the adhesive layer. The hot-melt adhesive is formed using a nonvolatile thermoplastic material that contains no water or solution, and remains in a solid state at room temperature. The hot-melt adhesive is a chemical substance that attaches objects together by applying the chemical substance in a dissolved state and cooling it. Further, the hot-melt adhesive has advantages of short adhesion time and being pollution-free, safe, hygienic, energy-saving, and low-cost. Since the hot-melt adhesive remains in the solid state at normal temperature, the hot-melt adhesive that has been processed into a film form or a fiber form in advance can be used. Alternatively, an adhesive layer that is formed over a base film made from polyester or the like in advance and then is processed into a film form can be used. A film in which a hot-melt film is formed over a base film made from polyethylene terephthalate is used here. The hot-melt film is formed using resin with a softening point that is lower than that of the base film. By performing heat treatment, only the hot-melt film is dissolved and becomes a rubbery state so that the dissolved hot-melt film is attached to an object. When cooling the hot-melt film, it is cured. As the hot-melt film, for example, a film containing as its main component ethylene-vinyl acetate copolymer (EVA), polyester, polyamide, thermoplastic elastomer, polyolefin, or the like can be used.

Next, the element formation layer110and the film109are cut, and a plurality of the element groups provided over the substrate101is separated into each element group (FIG. 2D). At this time, it is preferable to separate so that the film105and the film109are exposed without exposing the insulating film103. This is because, when the insulating film103is exposed, moisture or an impurity element is mixed into the insulating film103, thereby deteriorating characteristics of the element group102.

Generally, as shown inFIGS. 3A to 3C, in a case of separating a plurality of the element groups provided over the substrate101into each element group (FIG. 3C) after forming an insulating film103and a film105above an element group102without providing an opening104(FIG. 3A) and removing a substrate101to form a film109(FIG. 3B), there is a structure where the insulating film103is exposed on the side surface. On the other hand, a semiconductor device that is obtained using the manufacturing method described in this embodiment mode is made to have a structure where the opening104is formed between a plurality of the element groups102to provide the opening with the film105at the phase before removing the substrate101. Therefore, as shown inFIG. 2D, there can be a structure where the element group102and the insulating film103are covered with the film105and the film109when separated into each element. Much specifically, in the structure, the element group102is covered with the insulating film103and the film109without being exposed, and the insulating film103is covered with the film105and the film109without being exposed. Consequently, moisture or an impurity element is suppressed from entering into the element group102and the insulating film103, and reliability of a semiconductor device can be improved.

Through the above steps, a semiconductor device can be formed.

This embodiment mode will explain a manufacturing method of a semiconductor device which is different from that in the above embodiment mode with reference to drawings. Specifically, a manufacturing method of a semiconductor device of the present invention including a thin film transistor, a memory element, and an antenna will be explained with reference to drawings.

First, an insulating film202to be a base is formed over one surface of a substrate201, and a semiconductor film203is formed over the insulating film202(FIG. 5A). Note that the insulating film202and the semiconductor film203can be formed continuously.

As the substrate201, a glass substrate, a quartz substrate, a metal substrate or a stainless steel substrate where an insulating film is formed over one surface, a heat-resistant plastic substrate that can withstand a processing temperature in this process, or the like is preferably used. Such a substrate201does not have a limit in its area or shape; therefore, as long as a rectangular substrate one side of which is 1 meter or more is used as the substrate201, for example, productivity can be improved significantly. Besides, a semiconductor substrate such as a Si substrate may also be used.

The insulating film202can be provided by a CVD method, a sputtering method, or the like with a single-layer structure of an insulating film containing oxygen and/or nitrogen such as a silicon oxide (SiOx) film, a silicon nitride (SiNx) film, a silicon oxynitride (SiOxNy) (X>Y) film, or a silicon nitride oxide (SiNxOy) (X>Y) film; or a stacked structure thereof. When the insulating film to be a base has a two-layer structure, for example, it is preferable to form a silicon nitride oxide film as a first layer, and a silicon oxynitride film as a second layer. When the insulating film to be a base has a three-layer structure, for example, it is preferable to form a silicon oxide film as a first layer, a silicon nitride oxide film as a second layer, and a silicon oxynitride film as a third layer. Alternatively, it is preferable to form a silicon oxynitride film as a first layer, a silicon nitride oxide film as a second layer, and a silicon oxynitride film as a third layer. The insulating film to be a base serves as a blocking film that prevents impurities from the substrate201from entering.

The semiconductor film203can be formed with an amorphous semiconductor or a semi-amorphous semiconductor (SAS). Alternatively, a polycrystalline semiconductor film may be used. The SAS has an intermediate structure between an amorphous structure and a crystalline structure (including a single crystal and a polycrystal) and a third state which is stable in terms of free energy, and the SAS includes a crystalline region having short-range order and lattice distortion. In at least part of a region of the film, a crystal region of 0.5 to 20 nm can be observed. In a case of containing silicon as a main component, a Raman spectrum is shifted to a lower wavenumber side than 520 cm−1. A diffraction peak of (111) or (220) to be caused by a crystal lattice of silicon is observed in X-ray diffraction. Hydrogen or halogen of at least 1 atomic % or more is contained to terminate dangling bonds. The SAS is formed by performing glow discharge decomposition (plasma CVD) to a gas containing silicon. SiH4is given as the gas containing silicon. In addition, Si2H6, SiH2Cl2, SiHCl3, SiCl4, SiF4, or the like can also be used as the gas containing silicon. In addition, GeF4may also be mixed. The gas containing silicon may be diluted with H2, or H2and one or more rare gas elements of He, Ar, Kr, and Ne. A dilution ratio thereof may range from 2 to 1000 times; a pressure, approximately 0.1 to 133 Pa; a power supply frequency, 1 to 120 MHz, preferably, 13 to 60 MHz; and substrate heating temperatures, 300° C. or less. A concentration of an atmospheric constituent impurity such as oxygen, nitrogen, or carbon, as an impurity element in the film, is desirably 1×1020atoms/cm3or less; in particular, a concentration of oxygen is 5×1019atoms/cm3or less, preferably 1×1019atoms/cm3or less. Here, an amorphous semiconductor film is formed in 25 to 200 nm thick (preferably, 30 to 150 nm thick) with a material containing silicon (Si) as its main component (such as SixGe1−x) using a sputtering method, a CVD method, or the like.

Next, a crystalline semiconductor film is formed by crystallizing the amorphous semiconductor film203by a crystallization method such as a laser crystallization method, a thermal crystallization method using RTA or an annealing furnace, a thermal crystallization method using a metal element which promotes crystallization, or the like. In addition, the crystallization of the semiconductor film can also be performed by generating thermal plasma by application of a DC bias and applying the thermal plasma to the semiconductor film. Then, the obtained semiconductor film is etched into a desired shape to form crystalline semiconductor films203ato203f, and a gate insulating film204is formed so as to cover the semiconductor films203ato203f(FIG. 5B).

Hereinafter, an example of a manufacturing process of the semiconductor films203ato203fwill be briefly explained. First, an amorphous semiconductor film of 66 nm thick is formed by using a plasma CVD method. Next, after holding a solution containing nickel which is a metal element which promotes crystallization over the amorphous semiconductor film, a crystalline semiconductor film is formed by performing dehydrogenation treatment (at 500° C. for an hour) and thermal crystallization treatment (at 550° C. for 4 hours) to the amorphous semiconductor film. Thereafter, if necessary, the crystalline semiconductor film is irradiated with laser light and the crystalline semiconductor films203ato203fare formed by using a photolithography method.

In the case of forming the crystalline semiconductor film with a laser crystallization method, a continuous wave laser beam (CW laser beam) or a pulsed wave laser beam (pulsed laser beam) can be used. As the laser beam that can be used here, a laser beam oscillated from one or more of a gas laser such as an Ar laser, a Kr laser, and an excimer laser; a single crystal of a YAG laser, a YVO4laser, forsterite (Mg2SiO4), a YAlO3laser, and a GdVO4laser or a polycrystal (ceramic) of YAG, Y2O3, YVO4, YAlO3, and GdVO4doped with one or more kinds 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 can be used. By emitting a laser beam of second to fourth wave of a fundamental wave in addition to a fundamental harmonic of the above laser beams, a crystal having a large grain size can be obtained. For example, a second harmonic (532 nm) or a third harmonic (355 nm) of Nd: YVO4laser (fundamental, 1064 nm) can be used. At this time, the laser requires power density of approximately from 0.01 to 100 MW/cm2(preferably, approximately from 0.1 to 10 MW/cm2). The laser is emitted at a scanning rate of approximately 10 to 2000 cm/sec. Note that a laser using, as a medium, single crystal of YAG, YVO4, forsterite (Mg2SiO4), YAlO3, or GdVO4or polycrystal (ceramic) of YAG, Y2O3, YVO4, YAlO3, or GdVO4doped with one or more kinds of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as a dopant; an Ar ion laser; or a Ti: sapphire laser can be continuously oscillated. Further, pulse oscillation thereof can be performed with an oscillation frequency of 10 MHz or more by performing Q switch operation, mode synchronization, or the like. When a laser beam is oscillated with a repetition rate of 10 MHz or more, a semiconductor film is irradiated with a next pulse during the semiconductor film is melted by the laser beam and then is solidified. Thus, differing from a case of using a pulse laser with a low repetition rate, a solid-liquid interface can be continuously moved in the semiconductor film so that crystal grains, which continuously grow toward a scanning direction, can be obtained.

In addition, the crystallization of the amorphous semiconductor film by using the metal element for promoting crystallization is advantageous in that the crystallization can be performed at low temperature in short time and the direction of crystals becomes uniform, while there is a problem in that the property is not stable because the off current is increased due to a residue of the metal element in the crystalline semiconductor film. Therefore, it is preferable to form an amorphous semiconductor film serving as a gettering site over the crystalline semiconductor film. In order to form a gettering site, the amorphous semiconductor film is required to contain an impurity element such as phosphorous and argon; therefore, the amorphous semiconductor film is preferably formed by a sputtering method by which argon can be contained at a high concentration. Thereafter, heat treatment (an RTA method, thermal annealing using an annealing furnace, or the like) is performed to diffuse the metal element into the amorphous semiconductor film, and the amorphous semiconductor film containing the metal element is removed. Thus, the content of the metal element in the crystalline semiconductor film can be reduced or removed.

The gate insulating film204is formed by a single layer or a stacked layer of a film containing oxide of silicon or nitride of silicon by a CVD method, a sputtering method, or the like. Specifically, a film containing silicon oxide, a film containing silicon oxynitride, or a film containing silicon nitride oxide is formed in a single layer structure or formed by being stacked.

In addition, the gate insulating film204may also be formed by performing high-density plasma treatment to the semiconductor films203ato203fto oxide or nitride surfaces thereof. For example, the gate insulating film204is formed by plasma treatment where a mixed gas of a rare gas such as He, Ar, Kr, or Xe; and oxygen, nitrogen oxide (NO2), ammonia, nitrogen, hydrogen, and the like is introduced. In this case, when excitation of plasma is performed by introducing a microwave, high-density plasma can be generated at a low electron temperature. The surfaces of the semiconductor films can be oxidized or nitrided by oxygen radicals (OH radicals may be included) or nitrogen radicals (NH radicals may be included) generated by this high-density plasma.

With such treatment using high-density plasma, the insulating film having a thickness of 1 to 20 nm, typically 5 to 10 nm, is formed over the semiconductor films. Since a reaction of this case is a solid-phase reaction, an interface state density between the insulating film and the semiconductor films can be made extremely low. In such high-density plasma treatment, since the semiconductor films (crystalline silicon or polycrystalline silicon) are directly oxidized (or nitrided), variation in a thickness of the insulating film that is formed can be ideally made to be extremely small. In addition, since the semiconductor films in a crystal grain boundary of crystalline silicon are not oxidized too much, an extremely desirable state can be obtained. In other words, in the high-density plasma treatment described here, by solid-phase oxidation of the semiconductor film surfaces, the insulating film which has favorable uniformity and low interface state density can be formed without excessive oxidation in a crystal grain boundary.

As for the gate insulating film, only the insulating film formed by high-density plasma treatment may be used. Alternatively, an insulating film of silicon oxide, silicon oxynitride, silicon nitride, or the like may be deposited or stacked to the insulating film by a CVD method using plasma or a thermal reaction. In any case, characteristic variation can be reduced in a transistor including the insulating film formed by high-density plasma as part or the entire of the gate insulating film.

Moreover, the semiconductor films203ato203f, which is obtained by scanning the semiconductor film in one direction to be crystallized while irradiated with a continuous wave laser beam or a laser beam oscillating with a frequency of 10 MHz or more, have a characteristic that crystals are grown in a scanning direction of the beam. A transistor (TFT) in which characteristic variation is reduced and field effect mobility is high can be obtained by arranging the transistor so that the scanning direction is aligned with a channel length direction (a direction in which carriers are flown when a channel forming region is formed) and by combining the above gate insulating film.

Then, a first conductive film and a second conductive film are stacked over the gate insulating film204. The first conductive film is formed by a plasma CVD method, a sputtering method, or the like to have a thickness of 20 to 100 nm. The second conductive film is formed by a plasma CVD method, a sputtering method, or the like to have a thickness of 100 to 400 nm. The first conductive film and the second conductive film are formed with an element of tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium (Cr), niobium (Nb), and the like; or an alloy material or a compound material containing the element as its main component. Alternatively, the first conductive film and the second conductive film are formed with a semiconductor material typified by polycrystalline silicon doped with an impurity element such as phosphorus. As an example of a combination of the first conductive film and the second conductive film, a tantalum nitride (TaN) film and a tungsten (W) film, a tungsten nitride (WN) film and a tungsten film, a molybdenum nitride (MoN) film and a molybdenum (Mo) film, and the like can be given. Since tungsten and tantalum nitride have high heat resistance, heat treatment for thermal activation can be performed after forming the first conductive film and the second conductive film. In a case of not a two-layer structure but a three-layer structure, a stacked structure of a molybdenum film, an aluminum film, and a molybdenum film is preferably employed.

Next, a resist mask is formed using a photolithography method and etching treatment for forming a gate electrode and a gate line is performed to form a conductive film (hereinafter, referred to as a gate electrode205) serving as a gate electrode. Here, the gate electrode205is provided with a structure where any of the above materials are stacked.

Then, a resist mask is formed by a photolithography method and an impurity element imparting N-type conductivity is added to the semiconductor films203b,203c,203e, and203fat low concentration by an ion doping method or an ion implantation method to form N-type impurity regions206. As the impurity element imparting N-type conductivity, an element belonging to Group15is preferably used, and phosphorus (P) or arsenic (As) is used, for example.

Thereafter, a resist mask is formed by a photolithography method and an impurity element imparting P-type conductivity is added to the semiconductor films203aand203dto form P-type impurity regions207. As the impurity element imparting P-type conductivity, boron (B) is used, for example (FIG. 5C).

Next, an insulating film is formed so as to cover the gate insulating film204and the gate electrode205. The insulating film is formed by a plasma CVD method, a sputtering method, or the like with a single-layer structure or a stacked structure of a film containing an inorganic material such as silicon, oxide of silicon, and/or nitride of silicon, or a film containing an organic material such as an organic resin. Next, the insulating film is selectively etched by anisotropic etching, by which etching is performed mainly in a perpendicular direction, to form insulating films (also referred to as sidewalls)208in contact with side faces of the gate electrodes205. At the same time as the manufacturing of the insulating films208, the gate insulating film204is etched to form insulating films210. The insulating films208are used as masks for doping in subsequently forming source and drain regions.

Then, with the use of the resist mask formed by a photolithography method and the insulating films208as masks, an impurity element imparting N-type conductivity is added to the semiconductor films203b,203c,203e, and203fto form first N-type impurity regions209a(also referred to as LDD (Lightly Doped Drain) regions) and second N-type impurity regions209b. The concentration of the impurity element contained in the first N-type impurity regions209ais lower than that in the second N-type impurity regions209b. Through the above steps, N-type thin film transistors230b,230c,230e, and230f, and P-type thin film transistors230aand230dare completed (FIG. 5D).

Note that, in order to form an LDD region, there are a technique of using a lower conductive film of a gate electrode, which is formed as a stacked structure of two layers or more, as a mask of the gate electrode by etching or performing anisotropic etching or the like so as to provided the gate electrode in a tapered shape, and a technique of using an insulating film which is a sidewall as a mask. A thin film transistor that is formed by employing the former technique has a structure where an LDD region is disposed to overlap with a gate electrode by interposing a gate insulating film therebetween. However, in order to utilize etching or anisotropic etching so as to provide the gate electrode in a tapered shape in this structure, it is difficult to control the width of the LDD region, and an LDD region cannot be formed in some cases as long as an etching step is not performed preferably. On the other hand, with the latter technique of using the insulating film which is a sidewall as a mask, the width of an LDD region can be easily controlled, and the LDD region can be formed certainly, as compared with the former technique.

Subsequently, a single layer or a stacked layer of an insulating film is formed so as to cover the thin film transistors230ato230f(FIG. 6A). The insulating film covering the thin film transistors230ato230fis formed by an SOG method, a droplet discharging method, or the like with a single layer or a stacked layer of an inorganic material such as oxide of silicon and/or nitride of silicon, an organic material such as polyimide, polyamide, benzocyclobutene, acrylic, epoxy, or siloxane, or the like. For example, in a case where the insulating film covering the thin film transistors230ato230fhas a three-layer structure, it is preferable to form a film containing silicon oxide as an insulating film211of a first layer, a film containing a resin as an insulating film212of a second layer, and a film containing silicon nitride as an insulating film213as a third layer.

Note that heat treatment for recovering crystallinity of the semiconductor films, activating the impurity elements added to the semiconductor films, or hydrogenating the semiconductor films is preferably performed before forming the insulating films211to213or after forming one or a plurality of the insulating films211to213. The heat treatment is preferably performed by applying a thermal annealing method, a laser annealing method, an RTA method, or the like.

Next, the insulating films211to213are selectively etched by a photolithography method to form contact holes which expose the semiconductor films203ato203f. Subsequently, a conductive film is formed to fill the contact holes. The conductive film is patterned to form conductive films214serving as source and drain wirings.

The conductive films214are formed by a CVD method, a sputtering method, or the like with a single layer or a stacked layer of an element of 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. The alloy material containing aluminum as its main component corresponds to, for example, a material containing aluminum as its component and nickel, or an alloy material containing aluminum as its main component, nickel, and either carbon or silicon, or both. The conductive films214may have, for example, 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 (TiN) film, and a barrier film. Note that the barrier film corresponds to a thin film of titanium, nitride of titanium, molybdenum, or nitride of molybdenum. Aluminum and aluminum silicon have low resistance and are inexpensive, which are optimum for a material of the conductive films214. When upper and lower barrier layers are provided, generation of a hillock of aluminum or aluminum silicon can be prevented. By forming the barrier film of titanium that is an element having a high reducing property, even when a thin natural oxide film is formed over the crystalline semiconductor film, the natural oxide film can be reduced, so that favorable contact with the crystalline semiconductor film can be formed.

Then, an insulating film215is formed so as to cover the conductive films214(FIG. 6B). The insulating film215is formed with a single layer or a stacked layer of an inorganic material or an organic material by an SOG method, a droplet discharging method, or a printing method such as a screen printing method or a gravure printing method. In addition, the insulating film215is preferably formed to have a thickness of 0.75 to 3 μm.

Subsequently, the insulating film215is etched by a photolithography method to form contact holes which expose the conductive films214in the thin film transistors230a,230c,230d, and230f. Then, a conductive film is formed to fill the contact holes. The conductive film is formed of a conductive material using a plasma CVD method, a sputtering method, or the like. Next, the conductive film is patterned to form conductive films216ato216d. Note that each of the conductive films216band216dserves as one of a pair of conductive films included in a memory element that is formed later. Thus, the conductive films216band216dare preferably formed with a single layer or a stacked layer of titanium, or an alloy material or a compound material containing titanium as its main component. Titanium has low resistance, which leads to a reduction in size of a memory element and achievement of higher integration. In a photolithography step to form the conductive films216ato216d, wet etching processing is preferably performed so as not to damage the lower thin film transistors230ato230f, and hydrogen fluoride (HF) or ammonia peroxide is preferably used as an etchant.

Next, an insulating film217is formed so as to cover the end portions of the conductive films216ato216d. The insulating film217is formed with a single layer or a stacked layer of an inorganic material or an organic material by an SOG method, a droplet discharging method, or the like. In addition, the insulating film217is preferably formed to have a thickness of 0.75 to 3 μm.

Then, a conductive film218serving as an antenna is formed in contact with the conductive films216aand216c(FIG. 6C). The conductive film218is formed of a conductive material by a CVD method, a sputtering method, a printing method, a droplet discharging method, or the like. Preferably, the conductive film218is formed with a single layer or a stacked layer of an element of aluminum (Al), titanium (Ti), silver (Ag), copper (Cu), and gold (Au), or an alloy material or a compound material containing the element as its main component. Specifically, the conductive film218is formed by using paste containing silver by a screen printing method and then performing heat treatment at temperatures of 50 to 350° C. Note that an antenna having a preferable characteristic can be obtained by applying pressure at the time of the heat treatment, which is preferable. Alternatively, the conductive film218is formed by forming an aluminum film by a sputtering method and patterning the aluminum film. The aluminum film is preferably patterned by wet etching processing, and after the wet etching processing, heat treatment is preferably performed at temperatures of 200 to 300° C.

Next, an organic compound layer219serving as a memory element is formed to be in contact with the conductive films216band216d(FIG. 7A). A material of which property or state changes by an electrical effect, an optical effect, a thermal effect, or the like is used as a material for the memory element. For example, a material, of which property or state changes by melting due to Joule heat, dielectric breakdown, or the like to cause an upper electrode and a lower electrode to short, may be used. Therefore, a thickness of a layer used for the memory element (here, the organic compound layer) is preferably 5 to 100 nm, much preferably, 10 to 60 nm.

Here, the organic compound layer219is formed by a droplet discharging method, a spin coating method, a vapor deposition method, or the like. Subsequently, a conductive film220is formed to be in contact with the organic compound layer219. The conductive film220is formed by a sputtering method, a spin coating method, a droplet discharging method, a vapor deposition method, or the like.

Through the above steps, a memory element portion231aincluding a stacked body of the conductive film216b, the organic compound layer219, and the conductive film220, and a memory element portion231bincluding a stacked body of the conductive film216d, the organic compound layer219, and the conductive film220are completed.

Note that a feature of the above manufacturing steps is to perform the step of forming the organic compound layer219after the step of forming the conductive film218serving as the antenna because heat resistance of the organic compound layer219is not high.

As an organic material used for the organic compound layer, for example, an aromatic amine-based compound (that is, a compound having a benzene ring-nitrogen bond) such as 4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl (abbreviation: α-NPD), 4,4′-bis[N-(3-methylphenyl)-N-phenyl-amino]-biphenyl (abbreviation: TPD), 4,4′,4″-tris(N,N-diphenyl-amino)-triphenylamine (abbreviation: TDATA), 4,4′,4″-tris[N-(3-methylphenyl)-N-phenyl-amino]-triphenylamine (abbreviation: MTDATA), or 4,4′-bis(N-(4-(N,N-di-m-tolylamino)phenyl)-N-phenylamino)biphenyl (abbreviation: DNTPD), polyvinyl carbazole (abbreviation: PVK), a phthalocyanine compound such as phthalocyanine (abbreviation: H2Pc), copper phthalocyanine (abbreviation: CuPc), or vanadyl phthalocyanine (abbreviation: VOPc), or the like can be used. These materials have a high hole transporting property.

Besides, a material formed of a metal complex or the like having a quinoline skeleton or a benzoquinoline skeleton such as tris(8-quinolinolato)aluminum (abbreviation: Alq3), tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq3), bis(10-hydroxybenzo[h]-quinolinato)beryllium (abbreviation: BeBq2), or bis(2-methyl-8-quinolinolato)-4-phenylphenolato-aluminum (abbreviation: BAlq), a material formed of a metal complex or the like having an oxazole-based or thiazole-based ligand such as bis[2-(2′-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)2) or bis[2-(2′-hydroxyphenyl)benzothiazolato]zinc (abbreviation: Zn(BTZ)2), or the like can be used. These materials have a high electron transporting property.

The organic compound layer may have a single-layer structure or a stacked structure. In the case of a stacked structure, materials can be selected from the aforementioned materials to form a stacked structure. Further, the above organic material and a light-emitting material may be laminated. As the light-emitting material, 4-dicyanomethylene-2-methyl-6-[2-(1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]-4H-pyran  (abbreviation: DCJT), 4-dicyanomethylene-2-t-butyl-6-[2-(1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]-4H-pyran, periflanthene, 1,4-bis[2-(10-methoxy)-(1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]-2,5-dicyanobenzene, N,N′-dimethylquinacridone (abbreviation: DMQd), coumarin 6, coumarin 545T, tris(8-quinolinolato)aluminum (abbreviation: Alq3), 9,9′-bianthryl, 9,10-diphenylanthracene (abbreviation: DPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 2,5,8,11-tetra-t-buthylperylene (abbreviation: TBP), or the like can be used.

A layer in which the above light-emitting material is dispersed may be used. In the layer in which the above light-emitting material is dispersed, an anthracene derivative such as 9,10-di(2-naphthyl)-2-tert-butylanthracene (abbreviation: t-BuDNA), a carbazole derivative such as 4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP), a metal complex such as bis[2-(2′-hydroxyphenyl)pyridinato]zinc (abbreviation: Znpp2) or bis[2-(2′-hydroxyphenyl)benzoxazolato]zinc (abbreviation: ZnBOX), or the like can be used as a base material. In addition, tris(8-quinolinolato)aluminum (abbreviation: Alq3), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), bis(2-methyl-8-quinolinolato)-4-phenylphenolato-aluminum (abbreviation: BAlq), or the like can be used.

Such an organic material is changed its property by a thermal effect or the like; therefore, a glass transition temperature (Tg) thereof is preferably 50 to 300° C., much preferably, 80 to 120° C.

In addition, a material in which metal oxide is mixed with an organic material or a light-emitting material may be used. Note that the material in which metal oxide is mixed includes a state in which metal oxide is mixed or stacked with the above organic material or the above light-emitting material. Specifically, it indicates a state which is formed by a co-evaporation method using plural evaporation sources. Such a material can be referred to as an organic-inorganic composite material.

For example, in a case of mixing a substance having a high hole transporting property with metal oxide, it is preferable to use vanadium oxide, molybdenum oxide, niobium oxide, rhenium oxide, tungsten oxide, ruthenium oxide, titanium oxide, chromium oxide, zirconium oxide, hafnium oxide, or tantalum oxide as the metal oxide.

In a case of mixing a substance having a high electron transporting property with metal oxide, it is preferable to use lithium oxide, calcium oxide, sodium oxide, potassium oxide, or magnesium oxide as the metal oxide.

A material of which property changes by an electrical effect, an optical effect, or a thermal effect may be used for the organic compound layer; therefore, for example, a conjugated high molecular compound doped with a compound (photoacid generator) which generates acid by absorbing light can also be used. As the conjugated high molecular compound, polyacetylenes, polyphenylene vinylenes, polythiophenes, polyanilines, polyphenylene ethynylenes, or the like can be used. As the photoacid generator, aryl sulfonium salt, aryl iodonium salt, o-nitrobenzyl tosylate, aryl sulfonic acid p-nitrobenzyl ester, sulfonyl acetophenones, Fe-arene complex PF6 salt, or the like can be used.

Note that the example of using an organic compound material as the memory element portions231aand231bis described here; however, the present invention is not limited thereto. For example, a phase change material such as a material which changes reversibly between a crystalline state and an amorphous state or a material which changes reversibly between a first crystalline state and a second crystalline state can be used. In addition, a material which changes only from an amorphous state to a crystalline state can also be used.

The material which reversibly changes between a crystalline state and an amorphous state is a material containing a plurality of elements of germanium (Ge), tellurium (Te), antimony (Sb), sulfur (S), tellurium oxide (TeOx), tin (Sn), gold (Au), gallium (Ga), selenium (Se), indium (In), thallium (Tl), cobalt (Co), and silver (Ag). For example, a material based on Ge—Te—Sb—S, Te—TeO2—Ge—Sn, Te—Ge—Sn—Au, Ge—Te—Sn, Sn—Se—Te, Sb—Se—Te, Sb—Se, Ga—Se—Te, Ga—Se—Te—Ge, In—Se, In—Se—Tl—Co, Ge—Sb—Te, In—Se—Te, or Ag—In—Sb—Te may be used. The material which reversibly changes between the first crystalline state and the second crystalline state is a material containing a plurality of elements of silver (Ag), zinc (Zn), copper (Cu), aluminum (Al), nickel (Ni), indium (In), antimony (Sb), selenium (Se), and tellurium (Te), for example, Ag—Zn, Cu—Al—Ni, In—Sb, In—Sb—Se, or In—Sb—Te. When using this material, a phase change is carried out between two different crystalline states. The material which changes only from an amorphous state to a crystalline state is a material containing a plurality of elements of tellurium (Te), tellurium oxide (TeOx), palladium (Pd), antimony (Sb), selenium (Se), and bismuth (Bi), for example, Te—TeO2, Te—TeO2—Pd, or Sb2Se3/Bi2Te3.

Next, an insulating film221serving as a protective film is formed by an SOG method, a spin coating method, a droplet discharging method, a printing method, or the like to cover the memory element portions231aand231band the conductive film218serving as the antenna. The insulating film221is formed of a film containing carbon such as DLC (Diamond Like Carbon), a film containing silicon nitride, a film containing silicon nitride oxide, or an organic material, preferably, an epoxy resin.

Then, as described in the above embodiment mode, an opening is selectively formed in an element formation layer233having the thin film transistors230ato230f, the conductive film218serving as the antenna, the memory element portions231aand231b, and the like, and a film222is formed so as to fill the element formation layer233and the opening (FIG. 7B).

The film222can be a film made from polypropylene, polyester, vinyl, polyvinyl fluoride, polyvinyl chloride, or the like, paper of a fibrous material, a laminated film of a base film (polyester, polyamide, an inorganic vapor-deposited film, paper, or the like) and an adhesive synthetic resin film (an acrylic-based synthetic resin, an epoxy-based synthetic resin, or the like), or the like. The film is attached to an object to be treated by being subjected to heat treatment and pressure treatment. In performing heat treatment and pressure treatment, an adhesive layer provided over the uppermost surface of the film or a layer (not an adhesive layer) provided over the outermost layer is melted by heat treatment to be attached by applying pressure. An adhesive layer may be provided over the surface of the film; however, it is not necessarily provided. The adhesive layer corresponds to a layer containing an adhesive such as a thermosetting resin, a UV curing resin, an epoxy-based resin, or a resin additive. The film used for sealing is preferably coated with silica to prevent moisture or the like from entering the inside after sealing, and for example, a sheet material in which an adhesive layer, a film of polyester or the like, and silica coat are laminated can be used.

Next, the substrate201is thinned to be a substrate224by performing either grinding treatment or polishing treatment, or both to the substrate201(FIG. 8A). Here, the side of the substrate201on which the element formation layer223is not formed (back surface) is subjected to grinding treatment, and thereafter, the back surface of the substrate201is further subjected to polishing treatment to thin the substrate201, thereby obtaining the substrate224. It is preferable to thin the substrate201as much as possible in the case of performing grinding treatment or polishing treatment to the substrate201. However, the element formation layer233is easily stressed as the substrate201gets thinner; therefore, the substrate224is made to have a thickness of 5 to 50 μm, preferably 5 to 20 μm, and much preferably 5 to 10 μm.

Then, the substrate224is removed by chemical treatment (FIG. 8B). As chemical treatment, chemical etching is performed to an object to be treated by using a chemical solution. Here, the etching of the substrate224is performed by dipping the substrate224and the element formation layer233into a chemical solution. Any chemical solution is accepted as the chemical solution as long as the substrate can be removed, and for example, it is preferable to use a solution containing hydrofluoric acid as the chemical solution in a case of using a glass substrate as the substrate201. Note that, as the film222, it is preferable to use a material that is unlikely to react with the chemical solution, and an insulating film containing an epoxy resin is used here. In addition, since the insulating film202is in direct contact with the chemical solution after removing the substrate201, it is preferable to use a material that has resistance to the chemical solution as the insulating film202. For example, the insulating film202is provided preferably in a two-layer structure, where a silicon nitride oxide film is formed as a first layer and a silicon oxynitride film is formed as a second layer.

Next, sealing treatment is performed by providing a film225for a side of the element formation layer233(FIG. 9A). As the sealing treatment, the film225is provided on one side of the element formation layer233(a side on which the substrate201is removed), and the film225is made to attach to the element formation layer233by using a roller243as shown inFIG. 16.

The film225for sealing can be a film made from polypropylene, polyester, vinyl, polyvinyl fluoride, polyvinyl chloride, or the like, paper of a fibrous material, a laminated film of a base film (polyester, polyamide, an inorganic vapor-deposited film, paper, or the like) and an adhesive synthetic resin film (an acrylic-based synthetic resin, an epoxy-based synthetic resin, or the like), or the like. The film is attached to an object to be treated by being subjected to heat treatment and pressure treatment. In performing heat treatment and pressure treatment, an adhesive layer provided over the uppermost surface of the film or a layer (not an adhesive layer) provided over the outermost layer is melted by heat treatment to be attached by applying pressure. An adhesive layer may be provided over the surface of the film225; however, it is not necessarily provided. The adhesive layer corresponds to a layer containing an adhesive such as a thermosetting resin, a UV curing resin, an epoxy-based resin, or a resin additive. The film used for sealing is preferably coated with silica to prevent moisture or the like from entering the inside after sealing, and for example, a sheet material in which an adhesive layer, a film of polyester or the like, and silica coat are laminated can be used.

For example, as the film225, a film where a hot-melt adhesive containing a thermoplastic resin is provided over a base film such as polyethylene terephthalate can be used. The hot-melt adhesive remains in a solid state at room temperature but is dissolved by applying heat. Therefore, a surface of the element formation layer233is provided with the film having the hot-melt adhesive and then subjected to heat treatment and pressure treatment by the roller243; thus, the element formation layer233can be sealed. Note that, in the case of performing heat treatment with the roller243, the treatment has to be performed at such a high temperature that the hot-melt adhesive is dissolved enough. Accordingly, in a case of using metal such as aluminum for a stage241, there is fear that heat generated by the roller243is drawn to the stage241; thus, the hot-melt adhesive is not dissolved enough. Therefore, it is preferable to provide a thermal insulation material such as silicon rubber between the stage241and an object to be treated.

As the film222and the film225, a film subjected to antistatic treatment for preventing static electricity or the like (hereinafter, referred to as an antistatic film) may also be used. An antistatic film includes a film where an antistatic material is dispersed in a resin, a film to which an antistatic material is attached, and the like. A film containing an antistatic material may be a film having one side provided with an antistatic material, or a film having the both sides provided with an antistatic material. Further, in a film having one side provided with an antistatic material, a side containing an antistatic material may be attached to the inside or outside of the film. Note that an antistatic material may be provided over the entire surface or part of a film. An antistatic material herein includes metal, oxide of indium and tin (ITO), and a surfactant such as a zwitterionic surfactant, a cationic surfactant, and a nonionic surfactant. Instead, a resin material containing a cross-linked copolymer high molecular compound having a carboxyl group and a quaternary ammonium base in a side chain may be used as an antistatic material. An antistatic film may be obtained by attaching, kneading, or applying these materials to a film. When a semiconductor device is sealed with an antistatic film, the semiconductor element can be protected from external static electricity or the like when being handled as a product.

Note that, after performing sealing treatment of the element formation layer233with the film225, sealing may be performed so as to cover the film222, if necessary.

Then, the element formation layer233, the film222, and the film225are cut to separate into each element (FIG. 9B). At this time, it is preferable to separate so that the film222and the film225are exposed without exposing the element formation layer233. By covering the element formation layer233with the film222and the film225completely in such a manner, an impurity element or moisture is suppressed from mixing into a semiconductor element such as a thin film transistor from outside; thus, a highly reliable semiconductor device can be obtained.

Note that this embodiment mode can be implemented by being arbitrarily combined with the above embodiment mode. In other words, the material or the formation method described in the above embodiment mode can be used in combination also in this embodiment mode, and the material or the formation method described in this embodiment mode can be used in combination also in the above embodiment mode.

This embodiment mode will explain an example of application modes of a semiconductor device that is obtained by using the manufacturing method described in the above embodiment mode. Specifically, applications of a semiconductor device which can exchange data without contact will be explained below with reference to drawings. The semiconductor device which can exchange data without contact is also referred to as an RFID (Radio Frequency Identification) tag, an ID tag, an IC tag, an IC chip, an RF (Radio Frequency) tag, a wireless tag, an electronic tag, or a wireless chip, depending on application modes.

A semiconductor device80has the function of communicating data without contact, and includes a high frequency circuit81, a power supply circuit82, a reset circuit83, a clock generation circuit84, a data demodulation circuit85, a data modulation circuit86, a control circuit87for controlling other circuits, a memory circuit88, and an antenna89(FIG. 10A). The high frequency circuit81is a circuit which receives a signal from the antenna89and outputs a signal received by the data modulation circuit86from the antenna89. The power supply circuit82is a circuit which generates power supply potential from the received signal. The reset circuit83is a circuit which generates a reset signal. The clock generation circuit84is a circuit which generates various clock signals based on the received signal inputted from the antenna89. The data demodulation circuit85is a circuit which demodulates the received signal and outputs the signal to the control circuit87. The data modulation circuit86is a circuit which modulates a signal received from the control circuit87. As the control circuit87, a code extraction circuit91, a code determination circuit92, a CRC determination circuit93, and an output unit circuit94are provided, for example. Note that the code extraction circuit91is a circuit which separately extracts a plurality of codes included in an instruction transmitted to the control circuit87. The code determination circuit92is a circuit which compares the extracted code and a code corresponding to a reference to determine the content of the instruction. The CRC circuit is a circuit which detects the presence or absence of a transmission error or the like based on the determined code.

In addition, the number of memory circuits to be provided is not limited to one, and may be plural. An SRAM, a flash memory, a ROM, a FeRAM, or the like, or a circuit using the organic compound layer described in the above embodiment mode in a memory element portion can be used.

Then, an example of operation of a semiconductor device which can communicate data without contact of the present invention will be explained. First, a radio signal is received by the antenna89. The radio signal is transmitted to the power supply circuit82via the high frequency circuit81, and high power supply potential (hereinafter referred to as VDD) is generated. The VDD is supplied to each circuit included in the semiconductor device80. In addition, a signal transmitted to the data demodulation circuit85via the high frequency circuit81is demodulated (hereinafter, a demodulated signal). Further, a signal transmitted through the reset circuit83and the clock generation circuit84via the high frequency circuit81and the demodulated signal are transmitted to the control circuit87. The signal transmitted to the control circuit87is analyzed by the code extraction circuit91, the code determination circuit92, the CRC assessment circuit93, and the like. Then, in accordance with the analyzed signal, information of the semiconductor device stored in the memory circuit88is outputted. The outputted information of the semiconductor device is encoded through the output unit circuit94. Furthermore, the encoded information of the semiconductor device80is transmitted by the antenna89as a radio signal through the data modulation circuit86. Note that low power supply potential (hereinafter, VSS) is common among a plurality of circuits included in the semiconductor device80, and VSS can be set to GND.

Thus, data of the semiconductor device can be read by transmitting a signal from a reader/writer to the semiconductor device80and receiving the signal transmitted from the semiconductor device80by the reader/writer.

In addition, the semiconductor device80may supply a power supply voltage to each circuit by an electromagnetic wave without a power source (battery) mounted, or by an electromagnetic wave and a power source (battery) with the power source (battery) mounted.

Since a semiconductor device which can be bent can be manufactured by using the structure shown in the above embodiment mode, the semiconductor device can be provided over an object having a curved surface by attachment.

Next, an example of application modes of a semiconductor device which can exchange data without contact will be explained. A side face of a portable terminal including a display portion3210is provided with a reader/writer3200, and a side face of an article3220is provided with a semiconductor device3230(FIG. 10B). When the reader/writer3200is held over the semiconductor device3230included in the article3220, information on the article3220such as a raw material, the place of origin, an inspection result in each production process, the history of distribution, or an explanation of the article is displayed on the display portion3210. In addition, when a product3260is transported by a conveyor belt, the product3260can be inspected using a reader/writer3240and a semiconductor device3250provided over the product3260(FIG. 10C). Thus, by utilizing the semiconductor device for a system, information can be acquired easily, and improvement in functionality and added value of the system can be achieved. As shown in the above embodiment mode, a transistor or the like included in a semiconductor device can be prevented from being damaged even when the semiconductor device is attached to an object having a curved surface, and a reliable semiconductor device can be provided.

In addition, as a signal transmission method in the above semiconductor device which can exchange data without contact, an electromagnetic coupling method, an electromagnetic induction method, a microwave method, or the like can be used. The transmission system may be appropriately selected by a practitioner in consideration of an intended use, and an optimum antenna may be provided in accordance with the transmission method.

In a case of employing, for example, an electromagnetic coupling method or an electromagnetic induction method (for example, a 13.56 MHz band) as the signal transmission method in the semiconductor device, electromagnetic induction is caused by a change in magnetic field density. Therefore, the conductive film serving as the antenna is formed in an annular shape (for example, a loop antenna) or a spiral shape (for example, a spiral antenna).

In a case of employing, for example, a microwave method (for example, a UHF band (860 to 960 MHz band), a 2.45 GHz band, or the like) as the signal transmission method in the semiconductor device, the shape such as a length of the conductive film serving as an antenna may be appropriately set in consideration of a wavelength of an electromagnetic wave used for signal transmission. For example, the conductive film serving as an antenna can be formed in a linear shape (for example, a dipole antenna (FIG.12A)), a flat shape (for example, a patch antenna (FIG.12B)), a ribbon shape (FIGS. 12C and 12D), or the like. The shape of the conductive film serving as an antenna is not limited to a linear shape, and the conductive film serving as an antenna may be provided in a curved-line shape, a meander shape, or a combination thereof, in consideration of a wavelength of an electromagnetic wave.

The conductive film serving as an antenna is formed with 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 material is formed with a single-layer structure of an element of 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 these elements as its main component; or a stacked structure thereof.

In a case of forming a conductive film serving as an antenna by, for example, a screen printing method, the conductive film can be provided by selectively printing conductive paste in which conductive particles each having a grain size of several nm to several tens of μm are dissolved or dispersed in an organic resin. As the conductive particles, one or more of metal particles such as silver (Ag), gold (Au), copper (Cu), nickel (Ni), platinum (Pt), palladium (Pd), tantalum (Ta), molybdenum (Mo), and titanium (Ti), fine particles of silver halide, or dispersible nanoparticles can be used. In addition, as the organic resin included in the conductive paste, one or a plurality of organic resins each serving as a binder, a solvent, a dispersant, or a coating of the metal particle can be used. Typically, an organic resin such as an epoxy resin or a silicon resin can be used. In forming a conductive film, baking is preferably performed after the conductive paste is applied. For example, in a case of using fine particles (the grain size of which is 1 to 100 nm) containing silver as its main component as a material of the conductive paste, a conductive film can be obtained by curing the conductive paste by baking at temperatures of 150 to 300° C. Alternatively, fine particles containing solder or lead-free solder as its main component may be used; in this case, it is preferable to use a fine particle having a grain size of 20 μm or less. Solder or lead-free solder has an advantage such as low cost.

Besides the above material, ceramic, ferrite, or the like may be applied to an antenna. Further, a material of which dielectric constant and magnetic permeability are negative in a microwave band (metamaterial) can be applied to an antenna.

In a case of applying an electromagnetic coupling method or an electromagnetic induction method, and providing a semiconductor device including an antenna in contact with metal, a magnetic material having magnetic permeability is preferably provided between the semiconductor device and metal. In the case of providing a semiconductor device including an antenna in contact with metal, an eddy current flows in metal accompanying change in magnetic field, and a demagnetizing field generated by the eddy current impairs a change in magnetic field and decreases a communication distance. Therefore, an eddy current of metal and a decrease in communication range can be suppressed by providing a material having magnetic permeability between the semiconductor device and metal. Note that ferrite or a metal thin film having high magnetic permeability and little loss of high frequency wave can be used as the magnetic material.

In a case of providing an antenna, a semiconductor element such as a transistor and a conductive film serving as an antenna may be directly formed over one substrate, or a semiconductor element and a conductive film serving as an antenna may be provided over separate substrates and then attached to be electrically connected to each other.

Note that an applicable range of the flexible semiconductor device is wide in addition to the above, and the flexible semiconductor device can be applied to any product as long as it clarifies information such as the history of an object without contact and is useful for production, management, or the like. For example, the semiconductor device can be mounted on paper money, coins, securities, certificates, bearer bonds, packing containers, books, recording media, personal belongings, vehicles, food, clothing, health products, commodities, medicine, electronic devices, and the like. Examples thereof will be explained with reference toFIGS. 11A to 11H.

The paper money and coins are money distributed to the market and include one valid in a certain area (cash voucher), memorial coins, and the like. The securities refer to checks, certificates, promissory notes, and the like (FIG. 11A). The certificates refer to driver's licenses, certificates of residence, and the like (FIG. 11B). The bearer bonds refer to stamps, rice coupons, various gift certificates, and the like (FIG. 11C). The packing containers refer to wrapping paper for food containers and the like, plastic bottles, and the like (FIG. 11D). The books refer to hardbacks, paperbacks, and the like (FIG. 11E). The recording media refers to DVD software, video tapes, and the like (FIG. 11F). The vehicles refer to wheeled vehicles such as bicycles, ships, and the like (FIG. 11G). The personal belongings refer to bags, glasses, and the like (FIG. 11H). The food refers to food articles, drink, and the like. The clothing refers to clothes, footwear, and the like. The health products refer to medical instruments, health instruments, and the like. The commodities refer to furniture, lighting equipment, and the like. The medicine refers to medical products, pesticides, and the like. The electronic devices refer to a liquid crystal display device, an EL display device, a television device (a TV set and a flat-screen TV set), a cellular phone, and the like.

Forgery can be prevented by providing the paper money, the coins, the securities, the certificates, the bearer bonds, or the like with the semiconductor device. The efficiency of an inspection system, a system used in a rental shop, or the like can be improved by providing the packing containers, the books, the recording media, the personal belongings, the food, the commodities, the electronic devices, or the like with the semiconductor device. Forgery or theft can be prevented by providing the vehicles, the health products, the medicine, or the like with the semiconductor device; further, in a case of the medicine, medicine can be prevented from being taken mistakenly. The semiconductor device can be mounted on the foregoing article by being attached to the surface or being embedded therein. For example, in a case of a book, the semiconductor device may be embedded in a piece of paper; in a case of a package made from an organic resin, the semiconductor device may be embedded in the organic resin. By using a flexible semiconductor device, breakage or the like of an element included in the semiconductor device can be prevented even when the semiconductor device is mounted on paper or the like.

As described above, the efficiency of an inspection system, a system used in a rental shop, or the like can be improved by providing the packing containers, the recording media, the personal belonging, the food, the clothing, the commodities, the electronic devices, or the like with the semiconductor device. In addition, by providing the vehicles with the semiconductor device, forgery or theft can be prevented. Moreover, by implanting the semiconductor device in a creature such as an animal, an individual creature can be easily identified. For example, by implanting the semiconductor device with a sensor in a creature such as livestock, its health condition such as a current body temperature as well as its birth year, sex, breed, or the like can be easily managed.

Note that this embodiment mode can be implemented by being arbitrarily combined with the above embodiment mode. In other words, the material or the formation method described in the above embodiment mode can be used in combination also in this embodiment mode, and the material or the formation method described in this embodiment mode can be used in combination also in the above embodiment mode.

This embodiment mode will explain an example of application modes of a semiconductor device that is obtained by using the manufacturing method described in the above embodiment mode. Specifically, a semiconductor device having a displaying means will be explained with reference to drawings.

First, as a displaying means, a case of providing a pixel portion with a light-emitting element will be explained with reference toFIGS. 13A and 13B. Note thatFIG. 13Ashows a top view showing an example of a semiconductor device of the present invention, whereasFIG. 13Bshows a cross-sectional view ofFIG. 13Ataken along lines a-b and c-d.

As shown inFIG. 13A, a semiconductor device shown in this embodiment mode includes a scanning line driver circuit502, a signal line driver circuit503, a pixel portion504, and the like which are provided over a film225(a film-like substrate). In addition, a film222(a film-like substrate) is provided so as to sandwich the pixel portion504with the film225. The scanning line driver circuit502, the signal line driver circuit503, and the pixel portion504can be provided by forming thin film transistors each having any of the structures shown in the above embodiment mode over the film225.

The scanning line driver circuit502and the signal line driver circuit503receive a video signal, a clock signal, a start signal, a reset signal, or the like from an FPC (Flexible Printed Circuit)507serving as an external input terminal. Note that only the FPC is shown here; however, the FPC may be provided with a printed wiring board. In addition, as a thin film transistor, which forms the signal line driver circuit503or the scanning line driver circuit502, a structure where thin film transistors are stacked can be employed as shown in the above embodiment mode. By providing thin film transistors by being stacked, an area in which the signal line driver circuit503or the scanning line driver circuit502is occupied can be reduced; therefore, the pixel portion504can be formed to have a large area.

FIG. 13Bis a schematic view of a cross section inFIG. 13Ataken along lines a-b and c-d. Here, a case where thin film transistors included in the signal line driver circuit503and the pixel portion504are provided over the film225is shown. A CMOS circuit that is a combination of an n-type thin film transistor510aand a p-type thin film transistor510bhaving any of the structure shown in the above embodiment mode is formed as the signal line driver circuit503.

A thin film transistor that forms a driver circuit such as the scanning line driver circuit502or the signal line driver circuit503may be formed using a CMOS circuit, a PMOS circuit, or an NMOS circuit. A driver integration type in which a driver circuit such as the scanning line driver circuit502or the signal line driver circuit503is formed over the film225is described in this embodiment mode; however, it is not necessarily required, and a driver circuit can be formed outside the film225instead of over the film225.

The pixel portion504is formed with a plurality of pixels each including a light-emitting element516and a thin film transistor511for driving the light-emitting element516. A thin film transistor having any of the structures shown in the above embodiment mode can be applied to the thin film transistor511. Here, a first electrode513is provided so as to be connected to a conductive film214connected to a source or drain region of the thin film transistor511, and an insulating film217is formed to cover an end portion of the first electrode513. The insulating film217serves as a partition in a plurality of pixels.

As the insulating film217, a positive type photosensitive acrylic resin film is used here. The insulating film217is formed to have a curved surface at an upper end portion or a lower end portion thereof in order to make the coverage favorable. For example, in a case of using positive type photosensitive acrylic as a material of the insulating film217, the insulating film217is preferably formed to have a curved surface with a curvature radius (0.2 to 3 μm) only at an upper end portion. Either a negative type which becomes insoluble in an etchant by light irradiation or a positive type which becomes soluble in an etchant by light irradiation can be used as the insulating film217. Alternatively, the insulating film217can be provided with a single-layer structure of an organic material such as epoxy, polyimide, polyamide, polyvinylphenol, or benzocyclobutene, or a siloxane resin; or a stacked structure thereof. As shown in the above embodiment mode, the surface of the insulating film217can be modified to obtain a dense film by subjecting the insulating film217to plasma treatment and oxidizing or nitriding the insulating film217. By modifying the surface of the insulating film217, intensity of the insulating film217can be improved, and physical damage such as crack generation at the time of forming an opening or the like or film reduction at the time of etching can be reduced. In addition, by modifying the surface of the insulating film217, interfacial quality such as adhesion with a light-emitting layer514to be provided over the insulating film217is improved.

In addition, in the semiconductor device shown inFIGS. 13A and 13B, the light-emitting layer514is formed over the first electrode513, and a second electrode515is formed over the light-emitting layer514. The light-emitting element516is provided with a stacked structure of the first electrode513, the light-emitting layer514, and the second electrode515.

One of the first electrode513and the second electrode515is used as an anode, and the other is used as a cathode.

A material having a high work function is preferably used for an anode. For example, a single-layer film such as an ITO film, an indium tin oxide film containing silicon, a transparent conductive film formed by a sputtering method using a target in which indium oxide is mixed with zinc oxide (ZnO) of 2 to 20 wt %, a zinc oxide (ZnO) film, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film; a stacked layer of a titanium nitride film and a film containing aluminum as its main component; a three-layer structure of a titanium nitride film, a film containing aluminum as its main component, and another titanium nitride film; or the like can be used. When a stacked structure is employed, the electrode can have low resistance as a wiring and form a favorable ohmic contact. Further, the electrode can serve as an anode.

A material having a low work function (Al, Ag, Li, Ca, or an alloy thereof such as MgAg, MgIn, AlLi, CaF2, or Ca3N2) is preferably used for a cathode. In a case where an electrode used as a cathode is made to transmit light, a stacked layer of a metal thin film with a small thickness and a transparent conductive film (ITO, indium tin oxide containing silicon, a transparent conductive film formed by a sputtering method using a target in which indium oxide is mixed with zinc oxide (ZnO) of 2 to 20 wt %, zinc oxide (ZnO), or the like) is preferably used as the electrode.

Here, the first electrode513is formed using ITO which has a light-transmitting property as an anode, and light is extracted from the film225side. Note that light may be extracted form the film222side by using a material having a light-transmitting property for the second electrode515, or light can be extracted from both the film225side and the film222side by forming the first electrode513and the second electrode515with a material having a light-transmitting property (this structure is referred to as dual emission).

The light-emitting layer514can be formed with a single layer or a stacked structure of a low molecular material, an intermediate molecular material (including an oligomer and a dendrimer), or a high molecular material (also referred to as a polymer) by a method such as a vapor deposition method using an evaporation mask, an ink-jet method, or a spin coating method.

Note that the semiconductor device including a pixel portion is not limited to the above structure using a light-emitting element in a pixel portion as described above, and it also includes a semiconductor device using liquid crystals in a pixel portion. The semiconductor device using liquid crystals in a pixel portion is shown inFIG. 14.

FIG. 14shows one example of a semiconductor device having liquid crystals in a pixel portion. Liquid crystals522are provided between an orientation film521provided to cover a conductive film214and a first electrode513and an orientation film523provided over a film222. In addition, a second electrode524is provided to be in contact with the film222. An image is displayed by controlling light transmittance by controlling a voltage applied to the liquid crystals provided between the first electrode513and the second electrode524. Moreover, a spacer525is provided in the liquid crystals522to control the distance (cell gap) between the first electrode513and the second electrode524.

As described above, in the semiconductor device described in this embodiment mode, the pixel portion can be provided with a light-emitting element or liquid crystals.

Next, application modes of a semiconductor device having the above pixel portion will be explained with reference to drawings.

The following electronic devices can be given as application modes of a semiconductor device having the above pixel portion: a camera such as a video camera or a digital camera, a goggle type display (head mounted display), a navigation system, an audio reproducing device (car audio, an audio component, and the like), a computer, a game machine, a portable information terminal (a mobile computer, a cellular phone, a portable game machine, an electronic book, and the like), an image reproducing device provided with a recording medium (specifically, a device capable of processing data in a recording medium such as a digital versatile disc (DVD) and having a display which can display the image of the data), and the like. Hereinafter, specific examples thereof will be described.

FIG. 15Ashows a display, which includes a main body4101, a supporting stand4102, a display portion4103, and the like. The display portion4103is formed using a flexible substrate, which can realize a lightweight and thin display. In addition, the display portion4103can be curved, and can be detached from the support4102and the display can be mounted along a curved wall. Thus, the flexible display can be provided over a curved portion as well as a flat surface; therefore, it can be used for various applications. A flexible display, which is one application mode of a semiconductor device of the present invention, can be manufactured by using the flexible semiconductor device described in this embodiment mode or the above embodiment mode for the display portion4103, a circuit, or the like.

FIG. 15Bshows a display that can be wound, which includes a main body4201, a display portion4202, and the like. Since the main body4201and the display portion4202are formed using a flexible substrate, the display can be carried in a bent or wound state. Therefore, even in a case where the display is large-size, the display can be carried in a bag in a bent or wound state. A flexible, lightweight, and thin large-sized display, which is one application mode of a semiconductor device of the present invention, can be manufactured by using the flexible semiconductor device shown in this embodiment mode or the above embodiment mode for the display portion4202, a circuit, or the like.

FIG. 15Cshows a sheet-type computer, which includes a main body4401, a display portion4402, a keyboard4403, a touch pad4404, an external connection port4405, a power plug4406, and the like. The display portion4402is formed using a flexible substrate, which can realize a lightweight and thin computer. In addition, the display portion4402can be wound and stored in the main body by providing a portion of the main body4401with a storage space. Moreover, also by forming the keyboard4403to be flexible, the keyboard4403can be wound and stored in the storage space of the main body4401in a similar manner to the display portion4402, which is convenient for carrying around. The computer can be stored without taking a place by bending when it is not used. A flexible, lightweight, and thin computer, which is one application mode of a semiconductor device of the present invention, can be manufactured by using the flexible semiconductor device shown in this embodiment mode or the above embodiment mode for the display portion4402, a circuit, or the like.

FIG. 15Dshows a display device having a 20 to 80-inch large-sized display portion, which includes a main body4300, a keyboard4301that is an operation portion, a display portion4302, a speaker4303, and the like. The display portion4302is formed using a flexible substrate, and the main body4300can be carried in a bent or wound state with the keyboard4301detached. In addition, the connection between the keyboard4301and the display portion4302can be performed without wires. For example, the main body4300can be mounted along a curved wall and can be operated with the key board4301without wires. In this case, a flexible, lightweight, and thin large-sized display device, which is one application mode of a semiconductor device of the present invention, can be manufactured by using the flexible semiconductor device shown in this embodiment mode or the above embodiment mode for the display portion4302, a circuit, or the like.

FIG. 15Eshows an electronic book, which includes a main body4501, a display portion4502, operation keys4503, and the like. In addition, a modem may be incorporated in the main body4501. The display portion4502is formed using a flexible substrate and can be bent or wound. Therefore, the electronic book can also be carried without taking a place. Further, the display portion4502can display a moving image as well as a still image such as a character. A flexible, lightweight, and thin electronic book, which is one application mode of a semiconductor device of the present invention, can be manufactured by using the flexible semiconductor device shown in this embodiment mode or the above embodiment mode for the display portion4502, a circuit, or the like.

FIG. 15Fshows an IC card, which includes a main body4601, a display portion4602, a connection terminal4603, and the like. Since the display portion4602is formed to be a lightweight and thin sheet type using a flexible substrate, it can be formed over a card surface by attachment. When the IC card can receive data without contact, information obtained from the outside can be displayed on the display portion4602. A flexible, lightweight, and thin IC card, which is one application mode of a semiconductor device of the present invention, can be manufactured by using the flexible semiconductor device shown in this embodiment mode or the above embodiment mode for the display portion4602, a circuit, or the like.

As described above, an applicable range of a semiconductor device of the present invention is so wide that the semiconductor device of the present invention can be applied to electronic devices of various fields. Note that this embodiment mode can be implemented by being arbitrarily combined with the above embodiment mode. In other words, the material or the formation method described in the above embodiment mode can be used in combination also in this embodiment mode, and the material or the formation method described in this embodiment mode can be used in combination also in the above embodiment mode.

This application is based on Japanese Patent Application serial no. 2005-288141 filed in Japan Patent Office on Sep. 30 in 2005, the entire contents of which are hereby incorporated by reference.

EXPLANATION OF REFERENCE