Heating apparatus for heating objects to be heated, heating method for heating the objects to be heated, and storage medium in which computer-readable program is stored

The present invention provides a heating apparatus for heating objects to be processed, which can detect a temperature of the objects to be processed with higher precision and accuracy, thereby to achieve higher precision temperature control. A heating apparatus 2 includes a processing vessel 8 configured to contain therein a plurality of objects W to be processed, the objects W including objects 58a to 58e to be processed for temperature measurement, each object 58a to 58e having each corresponding elastic wave element 60a to 60e, a heating means 10 adapted for heating the objects W to be processed, and a holding means 22 adapted to hold the objects W to be processed. To the processing vessel 8, a transmitter antenna 52 adapted to transmit an electric wave for measurement toward each elastic wave element 60a to 60e, and a receiver antenna 52 adapted to receive an electric wave having a frequency corresponding to the temperature and generated from each elastic wave element 60a to 60e are provided. A temperature analyzer 66 adapted to obtain the temperature of the wafers W to be processed for temperature measurement is connected with the receiver antenna 52, and a temperature control unit 64 adapted to control the heating means 10 is in turn connected with the temperature analyzer 66.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon the prior Japanese Patent Application No. 2007-048125 filed on Feb. 27, 2007, and Japanese Patent Application No. 2008-033519 filed on Feb. 14, 2008, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heating apparatus for heating objects to be heated, such as semiconductor wafers or the like, in order to provide a heating process to the objects to be processed, and also relates to a heating method for heating the object to be processed and to a storage medium in which a computer-readable program is stored.

2. Background Art

In general, upon forming semiconductor integrated circuits, such as ICs or the like, various processes, such as film-forming, etching, oxidation and diffusion, annealing and the like, are repeatedly provided to each semiconductor wafer composed of a silicon substrate or the like. Of these processes, when the heating, which is representative of the film-forming process, is provided to each semiconductor, temperature control for the wafer is one of key factors. Namely, in order to keep a film-forming speed for a thin film to be formed on the wafer surface and/or face-to-face uniformity and in-plane uniformity of the film thickness higher and/or better, the temperature of each wafer should be controlled with higher precision.

For example, as the heating apparatus, a vertical-type heating apparatus, which can provide the heating process to multiple sheets of wafers at a time, will be described by way of example. First, the semiconductor wafers supported in a multistage fashion are loaded (carried) into a vertical-type processing vessel, and then the wafers are heated by a heating means provided around an outer circumference of the heating vessel so as to elevate the wafer temperature. Thereafter, the film-forming process is provided to the wafers by stabilizing the temperature and flowing a film-forming gas in the processing vessel. In this case, a thermo-couple is provided in and/or outside the processing vessel, such that the wafers can be kept at a predetermined temperature, by controlling the electric power to be applied to the heating means, based on temperature information obtained from the thermo-couple (e.g., see Patent Documents 1 and 2).

The processing vessel has a length sufficient for containing, for example, about 50 to 150 sheets of wafers therein. Therefore, upon performing the temperature control in the processing vessel, the interior of the processing vessel is divided into a plurality of heating zones in the vertical direction in order to perform the temperature control individually for each heating zone, so as to achieve higher resolution and precision temperature control. In this case, a separate thermo-couple is provided directly to a dummy wafer for experimental use, so as to experimentally obtain in advance a mutual relation between an actual temperature of the dummy wafer to be detected by the separate thermo-couple and a temperature to be measured by the thermo-couple provided in or outside the processing vessel. Thus, upon heating the wafers as products, the temperature control will be performed while referring to the obtained mutual relation.

In the temperature control method for the heating apparatus as described above, the thermo-couple is not directly contacted with the wafers as objects whose temperature is to be measured. Therefore, a correlation between the actual temperature of the wafers as the products is not always completely coincident with a value to be measured by the thermo-couple. Especially, due to attachment of undesired or unwanted deposits onto an inner wall face or the like of the processing vessel after repeated film-forming processes, and/or due to alteration of the gas flow rate and/or processing pressure, and/or due to fluctuation of electric power or the like, a difference from the mutual relation described above may tend to be increased too much, as such making it significantly difficult to appropriately control the wafer temperature.

There is also a demand for controlling the wafer temperature during raising and lowering the wafer temperature. However, if the thermo-couple as described above is employed in such a case, the difference between the actual wafer temperature and the value to be measured by the thermo-couple is further increased, thus making it quite difficult to respond to such a demand. To solve this problem, it might be envisioned that the thermo-couple is provided to the wafer itself. However, since the thermo-couple is wired, such a structure can not adapt itself to rotation and/or loading of the wafer. In addition, due to potential problems of metal contamination or the like attributable to the thermo-couple, such a structure can not be accepted.

With respect to a sheet-feeding-type processing apparatus, as disclosed in TOKUKAI No. 2004-140167, KOHO, it might also be envisioned to obtain the wafer temperature by employing a quartz resonator adapted to receive electromagnetic waves corresponding to the temperature. However, the heat resistance of the quartz is approximately 300° C. at the most, as such it can not be used for the heating apparatus to be operated under the temperature condition higher than 300° C.

SUMMARY OF THE INVENTION

The present invention was made in view of the above problems, and therefore it is an object of this invention to provide a heating apparatus for heating objects to be heated, a heating method for heating the objects to be heated and a storage medium in which a computer-readable program is stored, each of which is configured and/or intended to obtain a temperature, based on an electric wave transmitted from an elastic wave element composed of, for example, a langasite substrate element or LTGA (Lanthanum Tantalic acid Gallium Aluminum), so that the temperature of the objects to be processed can be precisely and accurately detected, in a wireless and real-time fashion, without causing metal contamination or the like, thereby providing higher precision temperature control.

From studies that we have made about the temperature measurement for the semiconductor wafers, it was found that the elastic wave element employing langasite or LTGA or the like will generate an elastic wave when subjected to electric stimulation. Thus, an electric wave is generated and transmitted, based on a sound wave. As such, we found that, by receiving the electric wave, the wafer temperature can be directly measured in a wireless fashion. The present invention is based on this knowledge.

The present invention is a heating apparatus for heating objects to be processed, comprising: a processing vessel, which can contain therein a plurality of objects to be processed including an object to be processed for temperature measurement, the object to be processed for temperature measurement being provided with an elastic wave element; a heating means provided around the outer circumference of the processing vessel and adapted to heat the plurality of objects to be processed; a holding means adapted to hold the plurality of objects to be processed and configured to load and unload the plurality of objects to be processed relative to the processing vessel; a transmitter antenna provided to the processing vessel and adapted to transmit an electric wave for measurement to the elastic wave element of the object to be processed for temperature measurement; a receiver antenna provided to the processing vessel and adapted to receive an electric wave generated from the elastic wave element of the object to be processed for temperature measurement and having a frequency corresponding to a temperature of the object to be processed for temperature measurement; a temperature analyzer connected with the receiver antenna and adapted to obtain the temperature of the object to be processed for temperature measurement based on the electric wave received by the receiver antenna; and a temperature control unit connected with the temperature analyzer and adapted to control the heating means based on an output of the temperature analyzer.

According to this invention, the transmitter antenna and the receiver antenna are provided to the processing vessel, so as to receive the electric wave generated from the elastic wave element composed of, for example, a langasite substrate element or LTGA or the like, thereby obtaining the temperature of the objects to be processed based on the electric wave. Thus, the temperature of the objects to be processed can be detected securely and accurately, in a wireless and real-time fashion, without causing metal contamination or the like, as such achieving higher precision temperature control. Besides, since the temperature can also be directly measured upon raising and lowering the objects to be processed, for example, the temperature rising rate and/or temperature lowering rate can be accurately controlled, as such providing more appropriate temperature rising and lowering control. Furthermore, since the temperature of the objects to be processed can be obtained in a wireless manner, a significantly exact temperature of the objects to be processed can be measured even in the case in which films are attached to the inner wall faces of the processing vessel.

In this case, for example, the transmitter antenna and the receiver antenna are respectively formed into a looped shape, so as to surround the circumference of the objects to be processed. Alternatively, for example, a plurality of heating zones are provided in the processing vessel, and the object to be processed for temperature measurement is provided in plural numbers so as to be located corresponding to each heating zone, and the transmitter antenna and the receiver antenna are also provided in plural numbers so as to be located corresponding to each zone, respectively. Alternatively, for example, the frequency bands of the elastic wave elements of the objects to be processed for temperature measurement are set to be different from one another for each heating zone.

Alternatively, for example, each of the objects to be processed for temperature measurement includes a plurality of elastic wave elements, and the frequency bands of the plurality of elastic wave elements are set to be different from one another. Alternatively, for example, the elastic wave elements are provided at least at a central portion and a peripheral portion of each object to be processed for temperature measurement. Alternatively, for example, the transmitter antenna and the receiver antenna are formed into a rod-like shape extending along a longitudinal direction of the processing vessel.

Alternatively, for example, the transmitter antenna and the receiver antenna are provided in plural numbers, with a predetermined space, along the circumferential direction of the objects to be processed. Alternatively, for example, a plurality of heating zones are provided in the processing vessel, and the object to be processed for temperature measurement is provided in plural numbers so as to be located corresponding to each heating zone, and the frequency bands of the elastic wave elements of the objects to be processed for temperature measurement are set to be different from one another for each heating zone.

Alternatively, for example, each of the objects to be processed for temperature measurement includes a plurality of elastic wave elements, and the frequency bands of the plurality of elastic wave elements are set to be different from one another. Alternatively, for example, the elastic wave elements are provided at least at a central portion and a peripheral portion of each object to be processed for temperature measurement. Alternatively, for example, the transmitter antenna and the receiver antenna are provided inside the processing vessel.

Alternatively, for example, the transmitter antenna and the receiver antenna are provided outside the processing vessel. Alternatively, for example, a loading area is provided outside the processing vessel, such that the holding means unloaded from the processing vessel can wait in the loading area, wherein an additional transmitter antenna and an additional receiver antenna respectively having the same structures as those of the transmitter antenna and the receiver antenna are provided in the loading area. Alternatively, for example, the transmitter antenna and the receiver antenna are contained in a protective tube, respectively.

Alternatively, for example, from the transmitter antenna, electric waves for measurement of the frequency bands different from one another corresponding the elastic wave elements of different frequency bands are sequentially swept and sent at predetermined intervals. Alternatively, for example, from the transmitter antenna, electric waves for measurement of the frequency bands different from one another corresponding to the elastic wave elements of different frequency bands are simultaneously sent.

Alternatively, for example, the transmitter antenna and the receiver antenna are integrated as a transmitter-receiver antenna. Alternatively, for example, a thermo-couple is provided to the processing vessel and/or heating means, and the temperature control unit controls the heating means, also referring to a measured value obtained from the thermo-couple. Alternatively, for example, the processing vessel has a plasma generating means for generating a plasma by a high-frequency power for assisting a heat process of the objects to be processed, and the frequency bands of the electric waves for measurement are set to be different from the frequency band of the high-frequency power. Alternatively, for example, the elastic wave element is formed of a surface acoustic wave element. Alternatively, for example, the elastic wave element is formed of a bulk acoustic wave element. Alternatively, for example, the elastic wave element is composed of a substrate element of a material selected from the group consisting of lanthanum tantalic acid gallium aluminium (LGTA), quartz (SiO2), zinc oxide (ZnO), Rochelle salt (potassium sodium tartrate: KNaC4H4O6), titanic acid lead zirconate (PZT: Pb(Zr, Ti)O3), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), litium tetraborate (Li2B4O7), langasite (La3Ga5SiO14), aluminum nitride, tourmaline, and poly vinylidene fluoride (PVDF).

The present invention is a heating method for heating objects to be processed, in which method a holding means holding a plurality of objects to be processed is introduced into a processing vessel provided with a transmitter antenna and a receiver antenna, the plurality of objects to be processed including an object to be processed for temperature measurement, and the object to be processed for temperature measurement being provided with an elastic wave element, and in which method a heating process is provided to the objects to be processed, by heating them by using a heating means provided around the outer circumference of the processing vessel, the method comprising: a transmission step of transmitting an electric wave for measurement from the transceiver antenna to the elastic wave element of the object to be processed for temperature measurement; a reception step of receiving an electric wave generated from the elastic wave element of the object to be processed for temperature measurement by using a receiver antenna, the elastic wave element having received the electric wave for measurement; a temperature analysis step of obtaining a temperature of the object to be processed for temperature measurement based on the electric wave received by the receiver antenna; and a temperature control step of controlling the heating means based on the temperature obtained in the temperature analysis step.

In this case, for example, a plurality of heating zones are provided in the processing vessel, and the object to be processed for temperature measurement is provided in plural numbers, corresponding to each heating zone, and the frequency bands of the elastic wave elements of the objects to be processed for temperature measurement are set to be different from one another for each heating zone. Alternatively, for example, a thermo-couple is provided to the processing vessel and/or heating means, and in the temperature control step, the heating means is controlled, with a measured value obtained from the thermo-couple being also referred to. Alternatively, for example, spare objects to be processed for temperature measurement are prepared in advance, so that the objects to be processed for temperature measurement can be automatically replaced by the spare objects to be processed for temperature measurement, as needed or periodically. Alternatively, for example, a heat process of the object to be processed is assisted by a plasma generated by a high-frequency power, and the frequency of the electric wave for measurement is set to be different from the frequency of the high-frequency power. Alternatively, for example, the elastic wave element is formed of a surface acoustic wave element or a bulk acoustic wave element.

The present invention is a storage medium in which a computer readable program is stored, the program being used for driving a computer to perform a heating method for heating objects to be processed, in which method a holding means holding a plurality of objects to be processed is introduced into a processing vessel provided with a transmitter antenna and a receiver antenna, the plurality of objects to be processed including an object to be processed for temperature measurement, and the object to be processed for temperature measurement being provided with an elastic wave element, and in which method a heating process is provided to the objects to be processed, by heating them by using a heating means provided around the outer circumference of the processing vessel, the method comprising: a transmission step of transmitting an electric wave for measurement from the transceiver antenna to the elastic wave element of the object to be processed for temperature measurement; a reception step of receiving an electric wave generated from the elastic wave element of the object to be processed for temperature measurement by using a receiver antenna, the elastic wave element having received the electric wave for measurement; a temperature analysis step of obtaining a temperature of the object to be processed for temperature measurement based on the electric wave received by the receiver antenna; and a temperature control step of controlling the heating means based on the temperature obtained in the temperature analysis step.

According to this invention, the following prominent effects can be obtained. Namely, the transmitter antenna and the receiver antenna are provided to the processing vessel, so as to receive the electric wave generated from the elastic wave element composed of, for example, a langasite substrate element or LTGA or the like, thereby obtaining the temperature of the objects to be processed based on the electric wave. Thus, the temperature of the objects to be processed can be detected securely and accurately, in a wireless and real-time manner, without causing metal contamination or the like, as such providing higher precision temperature control. In addition, because the temperature can also be directly measured upon raising and lowering the objects to be processed, for example, the temperature rising rate and/or temperature lowering rate can be accurately controlled, as such providing more appropriate temperature rising and lowering control. Furthermore, since the temperature of the objects to be processed can be obtained in a wireless manner, a significantly exact temperature of the objects to be processed can be measured even in the case in which films or the like are attached to the inner wall faces of the processing vessel.

DETAILED DESCRIPTION OF THE INVENTION

EXAMPLES

Hereinafter, one embodiment of the present invention will be detailed with reference to the accompanying drawings.FIG. 1is a cross-sectional schematic view showing a heating apparatus according to the present invention.FIGS. 2A and 2Bare diagrams respectively provided for illustrating a positional relationship between a processing vessel and a looped transmitter-receiver antenna,FIGS. 3A,3B, and3C are diagrams respectively provided for illustrating an objected to be processed for temperature measurement, to which an elastic wave element is provided,FIG. 4is a schematic diagram showing a temperature control system of the heating apparatus,FIG. 5is a flow-chart showing one example of a heating method of the present invention, andFIGS. 6A and 6Bare diagrams showing a principle of operation for explaining the principle of operation of the elastic wave element.

In the description below, a case in which a transmitter-receiver antenna formed by combining a transmitter antenna and a receiver antenna and used as both of the antennae will be discussed by way of example. Herein, a vertical-type heating apparatus will be described by way of example.

As shown inFIG. 1, a heating apparatus2includes a processing vessel8having a double-wall structure. The heating vessel8is composed of a cylindrical inner tube4formed from quartz, and a cylindrical outer tube6having a ceiling, formed from quartz, and arranged outside and concentrically with the inner tube4. Around the outer circumference of the heating vessel8, a heating furnace14is located. The heating furnace14includes a heating means10composed of a heater or the like, and a heat insulating material12. The heating means10is configured to heat a plurality of objects (or semiconductor wafers W) to be processed, which will be described below. The heating means10is provided over the whole inner side face of the heat insulating member12. A heating region of the processing vessel8is divided into multiple, for example, herein, five, heating zones16a,16b,16c,16d,16e,each arranged in the vertical direction for temperature control. The heating means10is composed of five heaters10a,10b,10c,10d,10e, each of which may or may not correspond to each heating zone16ato16e. These five heaters can be controlled individually. It should be noted that the number of the zones is not limited in particular to this aspect. To the heaters10ato10e, heater thermocouples17ato17eadapted for measuring temperatures of these heaters are provided, respectively.

A bottom end of the processing vessel8is supported by a cylindrical manifold18formed from, for example, stainless steel. A bottom end of the inner tube4is supported on a support ring20attached to an inner wall of the manifold18. It is noted that the manifold18may be formed from quartz or the like so that it can be molded integrally with the processing vessel8. Below the manifold18, a wafer boat (or holding means)22formed from quartz will be located, with multiple sheets of semiconductor wafers W (or objects to be processed) being loaded thereon. The wafer boat (or holding means)22is configured to be optionally raised and lowered in order to load and unload the semiconductor wafers W (or objects to be processed) relative to the processing vessel8. While a typical size of the semiconductor wafers W is, for example, 300 mm, in diameter, but it is not limited in particular to this size.

The wafer boat22is placed on a rotary table26via a heat insulating mould24formed from quartz. The rotary table26is supported on a rotation shaft30extending through a cover28adapted for opening and closing a bottom end opening of the manifold18. To a portion through which the rotation shaft30extends, a seal32formed from, for example, a magnetic fluid, is provided, such that the magnetic fluid seal32can airtightly seal and rotatably support the rotation shaft30. Between the periphery of the cover28and the bottom end of the manifold18, a seal member34composed of, for example, an O-ring or the like, is provided, so as to keep sealing ability for the processing vessel8.

The rotation shaft30described above is attached to a distal end of an arm38supported by a lifting mechanism36, such as a boat elevator or the like, such that the wafer boat22, cover28and the like can be raised and lowered together.

To a side portion of the manifold18, a gas introducing means40is provided. Specifically, the gas introducing means40includes gas nozzles42extending through the manifold18, such that each necessary gas can be supplied into the processing vessel8, with the flow rate of the gas being controlled. It should be appreciated that although only one of the gas nozzles42is exemplarily depicted in the drawing, they are, in fact, provided in plural numbers, corresponding to kinds of gases to be used. As the gas nozzles42, the so-called distribution nozzle extending upward in the processing vessel8and having a plurality of gas injection holes may also be used. In a side wall of the manifold18, an exhaust port44is provided for discharging the atmosphere in the processing vessel8from a space between the inner tube4and the outer tube6. To the exhaust port44, a vacuum exhaust system (not shown) including, for example, a vacuum pump and/or pressure control valve provided between the exhaust port44and the vacuum exhaust system, is connected.

Between the inner tube4and the wafer boat22, five internal thermo-couples46ato46eare provided, corresponding to the respective heaters10ato10e. Each internal thermo-couple46ato46eis contained in a single protective tube48formed from quartz. A bottom end of the protective tube48is bent so as to airtightly extend through the side portion of the manifold18. A detection value obtained by each of the thermo-couples17ato17dand46ato46eis inputted to a temperature control unit50composed of, for example, a microcomputer or the like. The detection value is used as supplementary data upon individually controlling the electric power to be supplied to each heater10ato10eduring the heating process, as will be described below.

In addition, a transmitter-receiver antenna52as one of features of the present invention is provided to the processing vessel8. As described above, the transmitter-receiver antenna52is formed by combining a transmitter antenna and a receiver antenna and serves as both of the antennae. However, the antenna52is not limited to this aspect, but it may be provided in a state in which the transmitter antenna and the receiver antenna are separated from each other.

Specifically, the transmitter-receiver antenna52, as shown inFIG. 2A, is formed into a loop-like shape, such that it is positioned outside the processing vessel8so as to surround it. In this case, the transmitter-receiver antenna52is composed of five transmitter-receiver antennae52a,52b,52c,52d,52e,corresponding to wafers58ato58eeach used for temperature measurement as will be described below. Namely, each transmitter-receiver antenna52ato52eis provided to surround the circumference of each corresponding wafer W. Each transmitter-receiver antenna52ato52e, as shown inFIG. 2B, is formed by inserting an antenna cable56composed of a conductor into a protective tube54. The protective tube54is composed of a ceramic material formed from, for example, quartz, alumina or the like, which material being transparent to electric waves and having adequate heat resistance and corrosion resistance. As the antenna cable56, platinum or the like can be used.

As shown inFIG. 1, besides the semiconductor wafers W as products, a dummy wafer and/or wafer for temperature measurement, as an object to be processed for temperature measurement, provided with an elastic wave element, which is one of features of this invention, is held on the wafer boat22. As the elastic wave element, it is possible to use any of a surface acoustic wave element and a bulk acoustic wave element. Specifically, five wafers58a,58b,58c,58d,58efor temperature measurement are held on the wafer boat22, corresponding to the respective heaters10ato10e. These five wafers58a,58b,58c,58d,58efor temperature measurement are held at optimal positions in which the heaters10ato10ecan be properly controlled, respectively. Namely, the wafers58a,58b,58c,58d,58eare positioned in the vicinity of the corresponding transmitter-receiver antennae52ato52e,respectively, so that even a weak electric wave can readily reach each antenna.

The wafers58a,58b,58c,58d,58einclude elastic wave elements60a,60b,60c,60d,60e(seeFIGS. 3A,3B, and3C), respectively. Thus, electric waves are transmitted from the transmitter-receiver antennae52ato52eto the elastic wave elements60ato60e, respectively. Then, the transmitter-receiver antennae52ato52ereceive electric waves generated from the elastic wave elements60ato60e,respectively.

As shown inFIGS. 3A and 3B, the elastic wave elements60ato60emay be disposed on the upper surface of the wafers for temperature measurement58ato58e. However, not limited thereto, as shown inFIG. 3C, the elastic wave elements60ato60emay be embedded in the wafers for temperature measurement58ato58e. The embedding manner is not specifically limited, and it is possible to interpose each of the elastic wave elements60ato60ebetween two very thin wafer members to be embedded therein. Alternatively, it is possible to form a hole in a surface of each of the wafers for temperature measurement58ato58ein which each of the elastic wave elements60ato60eare received and embedded.

For each elastic wave element60ato60eas, e.g., a surface acoustic wave element, for example, a langasite substrate element employing langasite (La3Ga5SiO14) can be used. On the other hand, LTGA (lanthanum tantalic acid gallium aluminium: La3Ta0.5Ga5.5-xAlxO14) can be used as the bulk acoustic wave element. In this case, frequency bands of the elastic wave elements60ato60eare preferably set to be different from one another in order to prevent mutual interference.

Now, a temperature control system employing the transmitter-receiver antennae52ato52ewill be described, also referring toFIG. 4. As shown inFIG. 4, the transmitter-receiver antennae52ato52eare electrically connected with a transmitter receiver64via lines62ato62e, respectively. The transmitter-receiver antennae52ato52eare configured to transmit electric waves to the elastic wave elements60ato60eas well as to individually receive electric waves sent from the corresponding elastic wave elements60ato60e, respectively. The respective lines62ato62emay be protected by inserting them in, for example, a protective tube formed from quartz, or otherwise these lines62ato62emay be gathered in a single line. It is noted that when the transmitter-receiver antennae52ato52eare separated into transmitter antennae and receiver antennae respectively, the transmitter receiver64is also separated into a transmitter and a receiver.

When the respective elastic wave elements60ato60eare adjusted to respond to frequency bands different from one another, different electric waves for measurement different from one another corresponding to the different frequency bands are sent from the transmitter of the transmitter receiver64. In this case, electric waves for measurement of the frequency bands different from one another may be simultaneously sent. Alternatively, electric waves for measurement of the frequency bands different from one another may be sequentially swept and sent at predetermined intervals such as 1 second.

The processing vessel8may have, as a processing apparatus, a plasma generating means for generating a plasma by a high-frequency power for assisting a heat process of the wafers W. In this case, the respective frequency bands of the electric waves for measurement are set to be different from the frequency of the high-frequency power such as 13.56 MHz or 400 kHz, in order to prevent generation of noises.

The transmitter receiver64is connected with a temperature analyzer66, and the temperature analyzer66is in turn connected with the temperature control unit50. The temperature analyzer66obtains a temperature of each wafer58ato58efor temperature measurement, i.e., a temperature of each heating zone, based on each electric wave received by each transmitter-receiver antenna52ato52e. Thereafter, based on an output concerning the temperature of each heating zone obtained by the temperature analyzer66, the temperature control unit50controls each heater10ato10e, individually and independently, via a heater drive unit68.

Each measured value of the temperature obtained by the thermo-couples17ato17eand46ato46eare also inputted to the temperature control unit50, respectively, so as to aid temperature control due to the heating means10described above. It is noted that the internal thermo-couples46ato46eand/or heater thermo-couples17ato17emay be omitted.

Returning toFIG. 1, the entire operation of the heating apparatus2constructed as described above is controlled by a control means70composed of, for example, a computer or the like. The temperature control unit50is under the control of the control means70, as such the control means70can optionally control the temperature control unit50. A program of the computer for performing the entire operation of the heating apparatus2is stored in a storage medium72, such as a floppy, a compact disc (CD), a hard disk, a flash memory and the like. Specifically, depending on a command from the control means70, start and stop of supplying each gas, flow rate control of the gas, and control of the processing temperature and/or processing pressure are performed.

Next, a heating method performed by employing the heating apparatus constructed as described above will be discussed, also referring toFIG. 5.FIG. 5is a flow-chart showing one example of the heating method of the present invention. Prior to performing a heating process, such as actual film-forming or the like, a mutual relation between the temperature of each wafer58ato58efor temperature measurement to be detected by the electric wave of the frequency generated from each elastic wave element60ato60ecorresponding to each heating zone and the electric power to be supplied to each heater10ato10eis obtained in advance. The mutual relation is then stored in the temperature control unit50. In the case of using the thermo-couples17ato17eand46ato46eas well, the mutual relation between the temperature detection value obtained therefrom and the temperature obtained from the electric wave of each elastic wave element60ato60eis also obtained in advance.

Next, a procedure upon providing a heating process, such as actual film-forming or the like, to the semiconductor wafers W will be described. First, when the semiconductor wafers W are in an unloaded state and kept in a waiting state in a loading area located in a lower portion of the heating apparatus2. The processing vessel8is kept at a processing temperature, or otherwise at a temperature lower than the processing temperature. Thereafter, the wafer boat22is loaded into the processing vessel8by raising it from below, with the multiple sheets of wafers W of an ordinary temperature being loaded in the wafer boat22. Consequently, the cover28will close the bottom end opening of the manifold18, as such hermetically sealing the processing vessel8. In the wafer boat22, besides the wafers W as the products, the wafers58ato58eor temperature measurement are held in positions respectively corresponding to the heating zones16ato16e.

Then, the internal space of the processing vessel8is maintained at a processing pressure, while the wafer temperatures are detected by the thermo-couples17ato17eand46ato46e, respectively. In addition, the wafer temperatures are detected from the electric waves to be generated from the elastic wave elements60ato60e,respectively. With operation of the temperature control system shown inFIG. 4, the electric power applied to the respective heaters10ato10eis increased so as to elevate the wafer temperature, as such the processing temperature can be stabilized and maintained at a predetermined value. Thereafter, processing gases for desired film-forming will be introduced into the processing vessel8from the gas nozzles42of the gas introducing means40, respectively.

After the processing gases are introduced into a bottom portion of the inner tube4through the gas nozzles42, respectively, they rise while contacting with the wafers W rotating therein, providing a film-forming reaction to the wafers W. Thereafter, the processing gases flow downward from the ceiling through a gap provided between the inner tube4and the outer tube6, and are then discharged outside the vessel from the exhaust port44. The temperature control of the wafers W during the process can be performed by controlling the electric power supplied to each heater10ato10eunder, for example, the PID control. In this case, the wafer temperature of each heating zone is first obtained from the electric wave generated from each elastic wave element60ato60e, and the obtained wafer temperature is then controlled to be a predetermined target temperature.

Also referring toFIGS. 6A and 6B, a principle of operation of the elastic wave elements60ato60ewill be described.FIG. 6Ais a diagram showing a principle of operation for explaining the principle of operation of the elastic wave element formed of a surface acoustic wave element, andFIG. 6Bis a diagram showing a principle of operation for explaining the principle of operation of the elastic wave element formed of a bulk acoustic wave element. As shown inFIG. 6A, each surface acoustic wave element60A is composed of a langasite substrate element as disclosed in, for example, TOKUKAI No. 2000-114920, KOHO, TOKUKAI No. 2003-298383, KOHO or TOKUKAI No. 2004-140167, KOHO, etc. The langasite substrate element includes a langasite substrate76of a quadrilateral shape having a piezoelectric function. The size of this langasite substrate76is, for example, approximately 10 mm×15 mm×0.5 mm. On a surface of the langasite substrate76, a pair of comb-like electrodes78a,78bare formed, and antennae80a,80bare attached to the electrodes78a,78b, respectively.

When a high-frequency voltage is applied to the comb-like electrodes78a,78b, respectively, by transmitting thereto a high-frequency electric wave corresponding to the natural frequency of the langasite substrate76as a transmission signal from the transmitter and receiver64, a surface acoustic wave is generated by excitation due to a piezoelectric effect of the langasite substrate76. In this case, the acoustic velocity is changed depending on the temperature of the langasite substrate76, and the surface acoustic wave in turn resonates depending on the acoustic velocity. Thus, a resultant resonance signal will be outputted as an electric wave from the antennae80a,80e.

Accordingly, by analyzing a time difference Δt between a reception signal to be obtained by receiving the outputted electric wave described above by using the transmitter receiver64and the aforementioned transmission signal, the temperature of the langasite substrate76can be detected. Namely, each element can be used as a wireless temperature detection element. Such a principle is applied to each elastic wave element60ato60e.

As shown inFIG. 6B, a bulk acoustic wave element60B represented by LTGA is also manufactured by interposing the bulk acoustic wave element60B between a pair of electrodes85aand85bconnected to a coil84.

Also in this case, by transmitting a predetermined high-frequency electric wave corresponding to the natural frequency of the bulk acoustic wave element60B from a transmitter receiver82, a signal outputted from the bulk acoustic wave element60B is received. By analyzing At between the transmittance signal and the reception signal, a temperature of the bulk acoustic wave element60B can be detected. Such a principle is applied to each elastic wave element60ato60e.

The frequency band of each element can be changed by altering a pitch of each electrode78a,78band a cutting out angle or a cutting out thickness from a single crystal. In this case, as described above, the elastic wave elements60ato60eare set at different frequency bands from one another. For instance, the element60ais set at a frequency band f1centered at, for example, 10 MHz, the element60bis set at a frequency band f2centered at, for example, 20 MHz, the element60cis set at a frequency band f3centered at, for example, 30 MHz, the element60dis set at a frequency band f4centered at, for example, 40 MHz, and the element60eis set at a frequency band f5centered at, for example, 50 MHz, respectively, thereby preventing interference.

As shown inFIG. 5, in actual temperature control, transmission electric power is first supplied from the transmitter receiver64to each transmitter-receiver antenna52ato52ecorresponding to each heating zones16ato16e, and an electric wave for measurement corresponding to the natural frequency of the langasite substrate (in a case of the surface acoustic wave element) or the LTGA substrate (in a case of the bulk acoustic wave element) is then transmitted from each transmitter-receiver antenna52ato52eto each elastic wave element60ato60eof each wafer58ato58efor temperature measurement (S1: transmission step). Then, each elastic wave element60ato60eof each wafer58ato58efor temperature measurement, which received the electric wave for measurement from each transmitter-receiver antenna52ato52e, generates a resonance corresponding to the temperature of each wafer58ato58efor temperature measurement, and radiates a resultant resonance signal (S2). The principle of generating the electric wave in this case is as previously described with reference toFIGS. 6A and 6B.

The electric wave generated is then received by each transmitter-receiver antenna52ato52ecorresponding to each heating zone and propagated toward the transmitter receiver64(S3: reception step). Consequently, the electric wave for each heating zone is analyzed by the temperature analyzer66, so that the temperature of each wafer58ato58efor temperature measurement, i.e., the temperature of the wafer W of each heating zone16ato16ecan be directly obtained (S4: temperature analysis step).

Thereafter, the temperature control unit50controls each heater10ato10eof the heating means10to be the target temperature, individually and independently, via the heater drive unit68, based on the temperature obtained by the temperature analysis step (S5: temperature control step). Thus, the wafer temperature (or temperature of the wafers for temperature measurement) can be directly measured and detected, thereby providing higher precision temperature control.

Such a series of controlling operations will be repeated (No of S6) until a predetermined processing time goes by (YES of S6). In this manner, the transmitter-receiver antennae52ato52eare provided to the processing vessel8so as to receive the electric wave transmitted from each elastic wave element60ato60ecomposed of, for example, the langasite substrate element or the LTGA element and obtain the wafer temperature based on the received electric wave. Thus, the temperature of the objects to be processed (or semiconductor wafers) W, i.e., each wafer58ato58efor temperature measurement, can be detected precisely and accurately, in a wireless and real-time fashion, without causing metal contamination or the like, thereby providing higher precision temperature control.

Because the wafer temperature can be directly measured also in the case of raising and lowering the objects W to be processed, for example, the temperature rising rate and/or temperature lowering rate can be accurately controlled, thus providing more appropriate temperature rising and lowering control. Furthermore, since the temperature of the objects W to be processed can be obtained in a wireless manner, a significantly exact temperature of the objects W to be processed can be measured even in the case in which films are attached to the inner wall faces of the processing vessel8.

In the actual temperature control, in order to perform higher precision temperature control, it is preferred to perform the temperature control also referring to the measured values respectively obtained from the heater thermo-couples17ato17eand/or internal thermocouples46ato46e, in addition to the temperature obtained from the temperature analyzer66.

If the aforementioned electric wave for temperature measurement and the electric wave transmitted from each elastic wave element60ato60eare strong enough, the number of the transmitter-receiver antennae52may be reduced to one fewer than five (5). Generally, in such a case, the electric wave for temperature measurement can be strengthened to some extent, while the electric wave transmitted from each elastic wave element60ato60eis remained weak. Accordingly, the transmitter-receiver antennae52fewer than five in number may be provided, while the receiver antennae may be additionally provided to other heating zones than those to which the transmitter-receiver antennae52are provided.

Furthermore, if the electric wave transmitted from each elastic wave element60ato60ecan reach the antenna of the corresponding heating zone, but is too weak to reach the antennae of the adjacent heating zones, there is no risk of interference. Accordingly, there is no need for setting the frequency band of each elastic wave element60ato60eto be different from one another. As such, all of the elastic wave elements may be set at the same frequency band. In addition, if the thermo-couples17ato17eand/or internal thermo-couples46ato46eare provided in the apparatus, the temperature of the processing vessel8can be elevated in advance to an appropriate temperature even upon idling time the wafers W are unloaded and the processing vessel8is vacant.

While, in the embodiment described above, the transmitter-receiver antennae52ato52eare provided outside the processing vessel8, the arrangement of these antennae is not limited to this aspect. For instance, the transmitter-receiver antennae52ato52emay be provided inside the processing vessel8as described in a first modification of the heating apparatus of the present invention shown inFIG. 7. In this case, the transmitter-receiver antennae52ato52eare provided between the inner tube4of the processing vessel8and the wafer boat22, respectively. InFIG. 7, like reference numerals are assigned to like components which are the same as those shown inFIG. 1.

Furthermore, while the looped antennae are employed as the transmitter-receiver antennae52ato52ein the embodiments respectively shown inFIGS. 1 and 7, the antennae are not limited to this aspect. For instance, rod-like transmitter-receiver antennae (including rod-like transmitter antennae and rod-like receiver antennae) may also be used.FIG. 8shows a second modification of the heating apparatus of the present invention of this type, andFIG. 9is a plan view showing one example of arrangement of the rod-like antennae of the heating apparatus shown inFIG. 8. It is noted that like reference numerals are assigned to like parts which are the same as those shown inFIG. 1.

InFIG. 8, a transmitter-receiver antenna90is provided outside the processing vessel8, the antenna90being formed into a rod-like shape extending along the longitudinal direction of the processing vessel8. InFIG. 9, the antenna90is composed of a plurality of, for example, four, rod-like transmitter-receiver antennae90a,90b,90c,90darranged with an equal space along the outer circumference of the processing vessel. It should be appreciated that the number of the antennae may be one, as well as may be increased or decreased depending on the strength of the electric wave. Alternatively, the rod-like transmitter-receiver antennae90ato90dmay be located inside the processing vessel8.

In the case of using such rod-like transmitter-receiver antennae90ato90d, each of the transmitter-receiver antennae90ato90dcan receive the electric waves transmitted from all of the elastic wave elements60ato60eof the corresponding heating zones16ato16e. Accordingly, in order to prevent the interference, the frequency bands of the respective elastic wave elements60ato60eare set to be different from one another. Also in this case, the same effect as one obtained from the heating apparatus shown inFIG. 1can be obtained.

While, in each embodiment described above, a case in which the transmitter-receiver antennae52ato52dor90ato90dare provided only to the processing vessel8has been discussed, the arrangement is not limited to this aspect. Namely, as described in a third modification of the heating apparatus of this invention, as shown inFIG. 10, a loading area94, in which the wafer boat22unloaded from the processing vessel8waits so as to load the wafers W therein, is provided below the processing vessel8. To the loading area94, additional transmitter-receiver antennae90x,90y(or additional transmitter antennae and additional receiver antennae) may be provided. As described above, in this loading area94, the loading operation of wafers W is performed, and in some cases, the wafer boat22itself is also moved in the horizontal direction. Thus, it is preferred that the transmitter-receiver antennae90x,90yare provided in a rod-like shape, rather than in a looped shape, and that these transmitter-receiver antennae90x,90yare arranged along a route in which the wafer boat22is moved in the horizontal direction.

With this configuration, the temperature of the wafers held by the wafer boat22can be obtained in a real-time fashion even after the heating process. Therefore, for example, it can be exactly recognized that the wafer temperature has been lowered to an extent able to be handled. Thus, the loading of wafers W can be started without taking unduly longer waiting time, as such enhancing the throughput. In addition, the elastic wave elements are disposed on the surfaces of the wafers58ato58efor temperature measurement in the respective embodiments. However, not limited thereto, the elastic wave elements may be embedded in the wafers58ato58efor temperature measurement.

While, in each embodiment described above, a case in which a single elastic wave element60ato60eis provided for each wafer58ato58efor temperature measurement has been discussed, the arrangement is not limited to this aspect. For instance, a plurality of elastic wave elements may be provided to a single wafer for temperature measurement.FIG. 11Ais a cross section showing a modification 1 of the wafer for use in temperature measurement, andFIG. 11Bis a plan view showing a modification 2 of the wafer for use in temperature. measurement. InFIG. 11A, the wafer58xfor temperature measurement is divided in two parts, and two elastic wave elements60x,60yare embedded in the wafer, one being located at a central portion and the other being located at a peripheral portion. The divided two wafer parts are finally joined together.

In this manner, each of the two elastic wave elements60x,60yassumes an embedded state in the wafer58xfor temperature measurement, thus preventing occurrence of contamination attributable to these elastic wave elements60x,60y.

In this way, in the case in which the two elastic wave elements60x,60yare embedded in the single wafer58xfor temperature measurement, the frequency bands of the respective elastic wave elements60x,60yshould be set different from each other in order to prevent interference.

In the case of the a modification 2 of the wafer for use in temperature shown inFIG. 11B, a plurality of, specifically, five elastic wave elements60f,60g,60h,60i, and60jare disposed on a center part and a peripheral part of a surface of a wafer58xfor use in temperature measurement. These elastic wave elements60f,60g,60h,60i, and60jmay be embedded in the wafer58xfor use in temperature measurement. In this case, a distribution of an in-plane temperature of the wafer can be measured. In this case, it is preferable that frequency bands of the respective elastic wave elements60f,60g,60h,60i, and60jare set to be different from each other in order to prevent interference.

Generally, in some film-forming processes, it is preferred that a proper temperature gradient is provided in the wafer surface upon the heating process or upon raising or lowering the wafer. In such a case, if the elastic wave elements60x,60yare respectively provided at the central portion and the periphery of the wafer58xfor temperature measurement as described above, a proper and accurate temperature gradient can be created in the wafer surface.

It is also contemplated that spare objects to be processed for temperature measurement each having the similar construction as that of each wafer58ato58e,58xfor temperature measurement as described above may be prepared in advance. In this way, the wafers58ato58e,58xfor temperature measurement, when degraded, may be automatically replaced by the spare objects to be processed for temperature measurement, as needed or periodically.

While, in each embodiment, the double-wall type processing vessel8including the inner tube4and the outer tube6has been discussed by way of example, the configuration is not limited to this aspect. For instance, this invention can also be applied to a single-wall type processing vessel. Furthermore, the processing vessel8is not limited to the vertical-type processing vessel, and this invention is also applicable to the horizontal-type processing vessel.

Additionally, while the film-forming process has been described herein as the heating process, it is not limited to this aspect. For instance, this invention can also be applied to oxidation and diffusion, annealing, etching, reforming and/or a process utilizing plasma. When using a plasma, as described above, it is preferable to differ the frequency of the high-frequency power for generating a plasma from the respective frequency bands of the electric waves for measurement, in order to prevent generation of noises.

For the elastic wave element, a substrate element of a material selected from the group consisting of lanthanum tantalic acid gallium aluminium (LGTA), quartz (SiO2), zinc oxide (ZnO), Rochelle salt (potassium sodium tartrate: KNaC4H4O6), titanic acid lead zirconate (PZT: Pb(Zr, Ti)O3), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), litium tetraborate (Li2B4O7), langasite (La3Ga5SiO14), aluminum nitride, tourmaline, and poly vinylidene fluoride (PVDF) can also be used. While the semiconductor wafer has been described herein by way of example as the object to be processed, it is not limited to this aspect. This invention is also applicable to glass substrates, LCD substrates, ceramic substrates and the like.