JP2002069653A - Thin film forming method, thin film forming apparatus and solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for forming a thin film, which form a thin film of superior film thickness uniformity on a large substrate and furthermore makes throughput high, and to provide a solar cell with a superior characteristic, and moreover, at a low cost. SOLUTION: The apparatus comprising a film forming chamber, inside of which several inductive coupling type electrode with shape of being folded over at the center and having a feeding part of high-frequency power and a grounding part at the each end of themselves, are arranged in parallel in the same plane, a high-frequency power source for supplying high-frequency power to the above feeding part, a means for controlling phase of the high-frequency power supplied to the above feeding part, and a waveform generator for modulating amplitude of the high-frequency power, is characterized by the configuration in which the high-frequency power has opposite phases opposite to each other at the adjacent feeding parts of the above several inductive coupling type electrodes, and in which the amplitude-modulated high-frequency power is supplied to the inductive coupling type electrodes and generates plasma, to form thin film on a substrate arranged so as to face the inductive coupling type electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a thin film, a thin film forming apparatus, and a solar cell. More particularly, the present invention relates to a thin film forming method for forming a thin film such as a-Si having excellent film thickness uniformity on a large-area substrate. Related to the device.

[0002]

2. Description of the Related Art Solar cells are attracting attention and being expected as a clean energy source. However, cost reduction is indispensable for widespread use of the solar cells. There is a strong demand for a thin film forming apparatus capable of forming at a high throughput. In order to form a thin film such as a-Si, a parallel plate type (capacitive coupling type) plasma CV is used.
Although the D apparatus has been put to practical use, the throughput is low because usually only one substrate can be processed. On the other hand, there is a problem that the apparatus becomes extremely large when processing a plurality of substrates simultaneously. Further, as the size of the substrate is increased, the uniformity of the thickness of the formed thin film is significantly reduced, so that a solar cell having desired characteristics cannot be obtained.

In order to produce a thin film having a high uniformity of film thickness, it is necessary to form a plasma having a uniform density over the entire substrate, and various studies have been made for this purpose. However, in the parallel plate type electrode system, it is not easy to form a plasma having a uniform density when the size of the substrate is increased, and the reason is as follows. That is, in the case of a parallel plate type electrode, in order to form a plasma having a uniform density, it is necessary to dispose the electrode with maintaining the distance between the two electrodes with high accuracy over the entire substrate. It becomes even more difficult. In addition, in the capacitive coupling type, a self-bias potential is generated in the electrode due to discharge between the electrode to which a high frequency is applied and the counter electrode at the ground potential and the wall of the film forming chamber, so that the plasma density is distributed. (Japanese Patent Laid-Open No. 7-94421). Furthermore, when the electrode becomes large, a standing wave is generated on its surface,
For this reason, plasma may be distributed. This becomes more pronounced at higher frequencies such as the VHF band. Therefore, the plasma maintenance mechanism is completely different from that of the capacitive coupling type, and the VHF band high frequency which is advantageous for high-speed film formation does not cause problems such as the electrode-to-electrode distance accuracy and electrode self-biasing inherent in the capacitive coupling type. There has been proposed a plasma CVD method using an inductively-coupled electrode that can generate a high plasma density. Specifically, for example, a ladder-shaped electrode (Japanese Patent Application Laid-Open No. Hei 4-236781)
And an inductively coupled electrode type plasma CVD apparatus using an electrode such as an electrode obtained by bending a conductive wire in a zigzag shape (Japanese Patent No. 2785442).

[0004]

However, the present inventors have studied various inductively coupled electrodes including the electrode having the above structure, and found that, for example, an inductively coupled electrode bent in a ladder shape or zigzag is It has been found that when the size of the substrate increases, the current path becomes difficult to be uniform, and a standing wave is partially generated in an unexpected place. Therefore, it is difficult to make the plasma density uniform. Difficult,
It has been found that it is difficult to use a conventional electrode structure for a large-area substrate. In the case of capacitively coupled electrodes, various studies have been made to improve the film thickness uniformity. For example, as a measure to solve the plasma density distribution caused by the self-bias, intermittent modulation of high-frequency power is performed. There is a film forming method of discharging (JP-A-7-94421) and the like.
However, the plasma maintenance mechanism is completely different between the inductive coupling type and the capacitive coupling type. That is, in the capacitive coupling type, plasma is maintained by secondary electron emission from the electrode and vibration of the sheath, but in the case of the inductive coupling type electrode,
This is because of the vibration of the electromagnetic field supplied from the electrode. Therefore, even if it is an effective measure for the capacitive coupling type, it is meaningless to apply it to the inductive coupling type as it is, and it is impossible to refer to the result of the conventional study.

Therefore, the present inventors conducted a basic study of plasma uniformization for an inductively coupled electrode, and in the above-described conventional inductively coupled electrode, an electrode structure using a standing wave, which was a problem, was used. Was considered. This electrode has, for example, a structure in which a power supply section is provided at one end of a rod-shaped or U-shaped electrode and the other end is grounded, and the distance between the grounding section and the power supply section is の of the high frequency.
In this case, a standing wave is generated at a predetermined position on the electrode by using a natural number multiple of the above, and a thin film having a uniform thickness is formed on the substrate by utilizing the generated plasma density distribution.

By adopting such an electrode configuration, it is possible to improve the film thickness uniformity as compared with the prior art.
Even with this new electrode configuration, as the substrate becomes larger and the electrode length increases, the plasma density differs between the power supply side and the ground side of the electrode, and the plasma density decreases toward the ground side, and as a result, the film density increases. It has been found that a new problem that the thickness becomes thinner occurs. This is considered to be because the high frequency is attenuated before propagating to the electrode tip, and the plasma density is distributed between the power supply side and the grounding part side. The apparatus configuration and film forming conditions that can eliminate the plasma density distribution and the film thickness distribution, which are considered to be caused by the above, and form a uniform thin film on a larger substrate were studied. Among them, the case of the capacitive coupling type is
Despite the completely different plasma maintenance mechanism,
It has been found that by AM modulating the high-frequency power, the state of the plasma changes, and furthermore, the plasma shape changes by the modulation method, and that these changes have reproducibility.
Further, in order to form a thin film on a wide substrate, it is necessary to arrange a plurality of the electrodes in parallel, but the film thickness distribution in the longitudinal direction of the electrodes may change depending on the phase of the high-frequency power supplied to each electrode. Do you get it. Based on these findings, the present inventor has further advanced the research, clarified the relationship between the power supply method, the modulation method, and the thin film distribution, and completed the present invention.

That is, an object of the present invention is to provide a large substrate with:
An object of the present invention is to provide a method and an apparatus for forming a thin film capable of forming a thin film having excellent film thickness uniformity. Another object of the present invention is to provide a method and an apparatus for forming a thin film capable of forming a thin film having excellent characteristics and uniformity of the film thickness at a high throughput. Another object of the present invention is to provide a solar cell having excellent characteristics and low cost by forming a solar cell using the above thin film forming method and apparatus.

[0008]

According to the thin film forming method of the present invention, an inductively-coupled electrode having a shape folded at the center and provided with a high-frequency power supply portion and a ground portion at both ends is provided on the same plane. A plurality of thin-film forming method for installing in parallel, generating a plasma by supplying high-frequency power to the plurality of inductively coupled electrodes, and forming a thin film on a substrate disposed facing the inductively coupled electrodes, A phase of the high-frequency power supplied to the power supply unit is set to be opposite to that of the adjacent power supply unit, and A
It is characterized by performing M modulation. By arranging a plurality of inductively coupled electrodes in this way and shifting the phase of the high frequency supplied to the power supply portion of the adjacent electrode by 180 degrees, the film thickness distribution in the electrode longitudinal direction as well as the substrate width direction is improved, A thin film having a uniform thickness can be formed on a large substrate. Furthermore, since the distribution of the plasma density shows a predetermined change depending on the condition of the AM modulation, the adjacent electrodes are set to the opposite phases to each other, and by selecting an appropriate modulation condition, the plasma density can be changed even under various film forming conditions. Can be made uniform, and a thin film with high film thickness uniformity can be formed. In the present invention, the AM modulation includes pulse modulation. In addition, by adjusting the frequency of the high-frequency power so that a standing wave is generated between the feeding part and the folded part, the plasma can be generated and maintained stably, and a thin film with higher reproducibility can be formed. It becomes possible.

In the AM modulation, a period for supplying high-frequency power and a period for cutting off high-frequency power are provided alternately.
During the formation of the thin film, the ratio of the period during which the high-frequency power is supplied or the modulation frequency of the AM modulation is changed. By performing high-frequency modulation in this manner, the film thickness uniformity can be more effectively improved.

The thin film forming apparatus according to the present invention comprises a plurality of inductively coupled electrodes having a shape folded in the center and having a power supply portion for high frequency power and a ground portion provided at both ends thereof. A film forming chamber, a high-frequency power supply for supplying high-frequency power to the power supply unit, means for controlling the phase of the high-frequency power supplied to the power supply unit, and a waveform generator for performing AM modulation of the high-frequency power, Comprising: a plurality of inductively coupled electrodes in which adjacent high-frequency power supply sections have mutually opposite high-frequency phases and supply AM-modulated high-frequency power to the inductively coupled electrodes to generate plasma; It is characterized in that a thin film is formed on a substrate arranged facing an electrode. In addition, the distance between the feeding part and the folded part is
It is preferable that the thickness is set to a natural number multiple of 1/2 of the high frequency excitation wavelength, so that generation and maintenance of plasma can be further stabilized, and a thin film having a uniform thickness with higher reproducibility can be formed.

Further, it is preferable that the plurality of inductively coupled electrodes are arranged in a plurality of layers, substrates are arranged on both sides of each electrode layer, and a thin film is formed on the plurality of substrates at the same time. By using the inductively coupled electrode, unlike the capacitively coupled electrode, a so-called multi-region film formation method can be employed without increasing the size of the device, so that simultaneous film formation is performed on many substrates. Can be constructed. The result is a significant increase in throughput,
For example, it greatly contributes to cost reduction of solar cells.

A solar cell according to the present invention is characterized in that at least one of the constituent thin films includes a thin film formed by the above-described thin film forming method or thin film forming apparatus of the present invention. As described above, the thin film forming apparatus and method of the present invention can form thin films of various film qualities with a uniform film thickness, and can select high-speed, high-quality film conditions, thereby maintaining high quality. Therefore, it is possible to reduce the manufacturing cost of the solar cell. Further, by using a multi-region film formation method, high throughput can be achieved, and it is possible to achieve further reduction in solar cell cost.

[0013]

Embodiments of the present invention will be described below. The thin film forming apparatus and method of the present invention will be described with reference to one configuration example of the thin film forming apparatus shown in FIG. As shown in the drawing, the thin film forming apparatus includes a plurality of inductively coupled electrodes 2 arranged in a film forming chamber 1 having a gas inlet 6 and an exhaust port 7 and a grounding portion 4 at one end of each electrode. And the power supply unit 3 at the other end is connected to the high-frequency power supply 9 via the coaxial cable 11. Here, a phase shifter 10 is arranged between the power supply unit 3 and the high-frequency power supply 9 in order to supply a high-frequency power of an opposite phase to the power supply unit of the adjacent electrode.
Further, a waveform generator 8 is connected to the high-frequency power supply 9 so that a desired AM modulation can be applied to the high-frequency power output from the power supply 9.

As the inductive coupling type electrode 2, an electrode having a shape folded at the center is used, and a power supply portion 3 for supplying high-frequency power and a ground portion 4 as a ground potential are provided at both ends. The shape bent at the center is exemplified by, for example, a U-shape or a U-shape, but this is not limited to a shape formed by bending a single bar and integrally forming the shape. A structure in which the linear electrodes are connected and fixed by a metal plate or the like may be used. The distance L between the feeding unit 3 and the grounding unit 4 and the folded unit 5 is n / 2 of the excitation wavelength λ of the high-frequency power.
It is preferable to make it twice (n is a natural number). That is, the feeding unit 3, the grounding unit 4, the folding unit 5, and the excitation wavelength are represented by L = n
By setting so as to satisfy the relationship of λ / 2, discharge can be generated and maintained stably. Here, the power supply unit and the grounding unit do not necessarily need to be provided in the film formation chamber, and an inductively coupled electrode is disposed through the film formation chamber, and power is supplied to a position outside the film formation chamber where L = n · λ / 2. Section and a ground section may be provided. Conversely, the oscillation frequency of the high-frequency power supply may be made variable, and the frequency may be changed so as to satisfy the above equation for a predetermined value of L. In the case of a U-shape, for example, the folded portion refers to a semicircular portion having a curvature,
In the case of a U-shape, it refers to a short-side linear portion between two longitudinal straight portions.

In the present invention, a phase shifter for controlling the phase of the high frequency wave is provided as a means for supplying high frequency waves having opposite phases to the power supply portions of the adjacent electrodes of the plurality of inductively coupled electrodes. In addition to the arrangement shown in FIG. 1, the arrangement shown in FIG. 2 is preferably used when the number of electrodes is large as in the case of FIG. In the arrangement of FIG. 1, the number of phase shifters increases as the number of electrodes increases, and it is necessary to adjust all the phase shifters in order to control the phases of adjacent electrodes. In the arrangement of FIG. Irrespective of this, since only one phase shifter is required, the system can be simplified. Also, the phase adjustment may be performed for one phase shifter. Further, the phases of the power supply units of the adjacent electrodes can be set to be opposite to each other without using the phase shifter.
In this case, for example, every other electrode, the length of the power supply unit and the folded portion is increased by a half wavelength of the high frequency, and the power supply unit is provided outside the film forming chamber, or is equivalent to the length of the half wavelength. A simple coaxial cable may be added to the power supply unit.

The high-frequency power supply according to the present invention includes:
A high-frequency power supply in a VHF band of up to 600 MHz is preferably used, but not limited to this, and for example, a microwave may be used. In the case of microwaves, a conversion connector for coaxial cable may be connected to the waveguide, and the coaxial cable may be connected to the power supply unit.

Further, in the present invention, a waveform generator 8 is provided for AM-modulating a high frequency. That is, the high frequency power output from the high frequency power supply 9 is AM-modulated by the waveform generator 8, and for example, a high frequency having a waveform as shown in FIG. 3 is supplied to the inductive coupling type electrode from the power supply unit. Here, as a signal wave to be modulated, for example, a sine wave (FIG. 3)
(A)) In addition to the rectangular wave and the triangular wave, a waveform such as a pulse that completely shuts off the output for a predetermined period (FIG. 3B) and a waveform in which these are superimposed (FIG. 3C) ), Etc., may be used.

Next, a method for forming a thin film according to the present invention will be described with reference to FIG. First, after evacuation of the film forming chamber 1 to a high vacuum,
The substrate 12 is heated to a predetermined temperature by a heater (not shown). Next, a reaction gas for deposition is introduced into the film formation chamber at a predetermined flow rate, and is set to a predetermined pressure by a main valve provided at the exhaust port 7. The high-frequency power supply 9 and the waveform generator 8 are turned on, the high frequency is AM-modulated by a predetermined signal wave, and the phase of the power supply portion of the adjacent electrode is adjusted while looking at a waveform monitor (not shown) installed at the power supply portion or the like. When high-frequency power is applied to each inductively-coupled electrode 2 by adjusting the phase shifter so as to be shifted by 180 degrees, plasma of uniform density is generated around the electrodes, and the reactive gas is decomposed and activated.
A thin film having excellent film thickness uniformity can be formed thereon.

Here, the manner in which the film thickness distribution changes according to the high frequency AM modulation condition and phase will be described with reference to a specific example. FIG. 4 is a graph showing a film thickness distribution measured in a longitudinal direction of an electrode when an a-Si film is formed under the following film forming conditions. FIGS. 4A to 4C show film thickness distributions obtained when pulse modulation is performed at different frequencies and high-frequency powers having opposite phases are supplied to adjacent electrodes. On the other hand, FIG.
(D) and (e) show that the same phase power is supplied to each electrode,
It is a film thickness distribution obtained in the case of 0 Hz pulse modulation (FIG. 4D) and continuous discharge without modulation (FIG. 4E). (Deposition conditions) Electrodes: 8 U-shaped electrodes (10 mm diameter) Power supply unit (grounding unit)-Folding unit distance 1.35 m Substrate: 1.0 mx 0.5 m High frequency: 81 MHz 25 W (per unit) AM modulation: pulse Frequency 100, 300, 500Hz
Duty ratio of 50% _Gas: SiH 4 _300sccm, 5Pa

When a high frequency wave having the same phase is applied to each electrode, as shown in FIG. 4, the film thickness is large on the power supply portion side, decreases toward the folded portion, then increases, reaches a local maximum, and decreases again. Film thickness distribution. Such a film thickness distribution is
It is observed when a large-sized substrate (1 m) close to the electrode length (1.35 m) is used to supply in-phase high-frequency waves. On the other hand, when high-frequency waves having opposite phases are supplied between the adjacent electrodes, a flattened distribution can be obtained as a whole as compared with the case of in-phase. In addition, it can be seen that by performing pulse modulation and changing the frequency, the relative film thickness ratio tends to change between the power supply portion side and the tip side of the electrode. As is clear from the above, by disposing a plurality of U-shaped electrodes, supplying high-frequency waves having opposite phases to the power supply portions of adjacent electrodes, and appropriately selecting the AM modulation conditions, various film forming conditions can be obtained. Thus, the plasma density can be made uniform, and a thin film having excellent film thickness uniformity can be formed even with a large substrate of 1 m or more.

In the specific example shown in FIG.
This shows the effect of changing the frequency using modulation.
However, other than the modulation frequency, other factors such as the modulation factor and the duty ratio may be used.
Similar effects can be obtained using modulation parameters.
You. Therefore, it changes according to the film forming conditions such as pressure and high frequency power.
By selecting the tuning parameters as appropriate,
Achieve film thickness uniformity on large substrates even under film conditions
It becomes possible. For reference, various modulation parameters
The film thickness distribution changes depending on the meter.
This will be described by an experiment performed using. In this experiment, the figure
6 was used. Where the electrodes
Is a rod-shaped electrode with an outer diameter of 10 mm and a length of 1.6 m.
The distance between the center axes of the eight electrodes is 32.5 mm.
Arranged. The distance between the electrode and the substrate is 50 mm.
Was. A substrate (length 500 mm) 12 is placed in the film forming chamber 1,
Heated to 200 ° C, ₄Introduce 300 sccm of gas
Then, the pressure was set to 5 Pa. Modulated under various conditions
High-frequency power is supplied to the electrodes to generate plasma and the substrate
An a-Si thin film was formed thereon. The high frequency is
80MHz, input power is 31W (per electrode)
The phases of the power supply sections of the respective electrodes were the same. Modulation conditions
Visual observation of the change in the plasma light and dark shape due to
The thickness distribution of the formed a-Si film was measured. The resulting
An example is shown in FIGS.

FIG. 7A is a graph showing the film thickness distribution in the electrode direction when a thin film is formed by supplying a high frequency without any modulation (continuous discharge). Note that the electrode center point corresponds to a position of 250 mm in the graph. FIG.
8 (b) and 8 (c) and FIGS. 8 (a) and 8 (b) show the film thickness distribution when an a-Si thin film is formed by changing the modulation degree, frequency and duty ratio (pulse modulation) of AM modulation. It is.
When high-frequency power is supplied to the electrode without applying AM modulation, a plasma shape that is bright on the power supply portion side of the electrode and darkens at the ground portion is observed, and the film thickness distribution is, as shown in FIG. It became thicker on the power supply side and thinner at the tip. On the other hand, when an AM-modulated high frequency is supplied, the plasma shape changes, and the film thickness distribution changes as shown in FIGS. 7 (b) and 7 (c) and FIGS. 8 (a) and 8 (b). did. For example, when high-frequency power with a modulation factor of 30% and a modulation frequency of 1 kHz is supplied (FIG. 7B), the plasma on the power supply unit side is darker than in the case of continuous discharge, and the film thickness distribution is in this plasma state. It was found to change correspondingly.

From the experimental results shown in the figure, it can be seen that when the modulation degree of the AM modulation is increased, the plasma density is reduced on the power supply side, and when the modulation frequency is increased, the plasma density is reduced on the power supply side, and at the same time the ground side is reduced. It was found that the plasma density increased. If the duty ratio (pulse modulation) is further increased, the plasma density increases along the electrodes, and the plasma density distribution and the formed film thickness distribution can be changed by appropriately adjusting the modulation conditions, such as increasing the plasma density on the power supply side. It was revealed. Conversely, by adjusting these parameters, a plasma having a desired distribution can be generated, and a thin film having a desired film thickness uniformity can be formed.

FIG. 8 (c) shows a period during which high-frequency power is supplied and a period during which high-frequency power is turned off as shown in FIG. 3 (c) by adjusting modulation conditions so as to make the plasma density uniform along the electrodes. Is a film thickness distribution when an a-Si film is formed by supplying high-frequency power having a waveform provided with. That is, in the device configuration of FIG. 6, by superimposing pulse modulation on 1 kHz AM modulation, a-Si having extremely excellent film thickness uniformity is obtained.
It can be seen that a film can be obtained.

On the other hand, it is known that the distribution of the plasma density fluctuates depending on film forming conditions such as high frequency power and pressure. Therefore, in a conventional thin film forming apparatus, a film having a high film thickness uniformity can be obtained under certain conditions. However, there is a problem that a uniform film thickness cannot be obtained, for example, under a film forming condition capable of obtaining a high quality film. However, as described above, by optimizing the AM modulation, it is possible to correct a change in the plasma density distribution due to the film formation under any film forming conditions and form a thin film having excellent film thickness uniformity. it can. For example, when the high-frequency power is increased for high-speed film formation, the plasma density on the power supply unit side is relatively higher than that on the ground unit side. In this case, for example, the AM modulation degree increases, the modulation frequency increases, In the case of pulse modulation, the plasma density can be made uniform along the electrodes by any one of the reductions in the duty ratio or a combination thereof. Further, from the viewpoint of film quality and film formation rate, when the pressure is increased, the plasma density on the power supply side becomes relatively low, so that the reverse operation may be performed. As described above, it is possible to form a thin film having a uniform thickness under any film forming conditions by using any one of the modulation degree, the modulation frequency, and the duty ratio of the AM modulation, or a combination thereof. Becomes

In the above-described thin film forming method, a high-frequency power AM-modulated under a modulation condition optimized in advance with respect to the film forming condition may be supplied to the electrode to form the thin film. The modulation condition may be changed while observing the state. Also, even in a state where the plasma density is distributed, in order to finally obtain a uniform film thickness over the entire substrate,
The modulation condition may be changed during the formation of the thin film. In this case, A
It is preferable to change the modulation frequency of M modulation or the duty ratio of the pulse. By such a film forming method, for example, films having different film quality and the like in the film thickness direction can be formed.

The thin film forming method and apparatus shown in FIG. 1 is a method and apparatus for forming a thin film on one substrate. The thin film forming apparatus of the present invention is arranged in a substrate width as shown in FIG. It is preferable to adopt a structure in which a plurality of electrode rows are further arranged at predetermined intervals, and a multi-region film formation method in which substrates are arranged on both sides of each electrode. With such a configuration, a thin film can be formed simultaneously on a large number of substrates (six in the example in the figure), and the throughput can be greatly increased. Moreover, the distance between the electrode and the substrate is 30 to
Since the thickness can be set to about 60 mm, a large number of substrates can be simultaneously formed in a small space, so that a thin film forming apparatus having an excellent throughput ratio to the installation area of the apparatus can be realized.

As described above, the thin film forming apparatus and method of the present invention
Although the description has mainly been given of the case where the present invention is applied to an a-Si film,
It is needless to say that the present invention is not limited to the a-Si film and can be applied to various thin film formations by appropriately selecting a reactive gas. In addition, by using the thin film forming method and the thin film forming apparatus described above, the high frequency power supplied to each electrode is made to be in opposite phase with the adjacent electrode, and further AM-modulated, so that a high quality semiconductor thin film can be formed at a high speed. Becomes
Moreover, since it has excellent film thickness uniformity, it is suitably used for the production of a large-sized substrate solar cell. In addition, by employing the above-described multi-region film formation method, it is possible to form a film on many substrates at the same time without increasing the size of the apparatus. In order to spread the technology, cost reduction, which is the biggest issue, can be achieved. In the present invention, the solar cell configuration is pin
Any of a structure, a pn structure, and a tandem structure in which these are laminated may be used, and the thin film forming method and the forming apparatus of the present invention are used for forming the p layer, the i layer, and the n layer.

[0029]

As described above, the thin film forming method and the thin film forming apparatus of the present invention make it possible to form a thin film having excellent film thickness uniformity on a large substrate. Moreover, it is possible to provide a thin film forming apparatus having a high throughput ratio to the apparatus installation area.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of a thin film forming apparatus of the present invention.

FIG. 2 is a schematic diagram showing another example of a high-frequency power supply system according to the present invention.

FIG. 3 is a conceptual diagram showing an AM-modulated high-frequency waveform.

FIG. 4 is a graph showing a relationship between a modulation condition, a phase of high-frequency power, and a film thickness distribution.

FIG. 5 is a schematic view showing one example of a high-throughput thin film forming apparatus of the present invention.

FIG. 6 is a schematic diagram showing a structure of a device used in an experiment of AM modulation.

FIG. 7 is a graph showing a relationship between a modulation condition and a film thickness distribution.

FIG. 8 is a graph showing a relationship between a modulation condition and a film thickness distribution.

[Explanation of symbols]

 1 film forming chamber, 2 inductive coupling type electrode, 3 power supply section. 4 Grounding part, 5 Folding part, 6 Gas inlet, 7 Exhaust port, 8 Waveform generator, 9 High frequency power supply, 10 Phase shifter, 11 Coaxial cable, 12 Substrate, 13 Substrate holder.

 ──────────────────────────────────────────────────続 き Continuing from the front page (71) Applicant 500132638 Akihisa Matsuda 1-1-1 Umezono, Tsukuba-shi, Ibaraki 2nd Central Institute of Advanced Industrial Science and Technology (71) Applicant 500132649 Michio Kondo 1 Umezono, Tsukuba-shi, Ibaraki Chome 1-1 Central 2 National Institute of Advanced Industrial Science and Technology (74) The above two agents 100111051 Patent Attorney Jiro Nakanishi (72) Inventor Norikazu Ito 5-8-1, Yotsuya, Fuchu-shi, Tokyo Anelva Shares In-company (72) Inventor Kaoru Watanabe 5-8-1, Yotsuya, Fuchu-shi, Tokyo Inside Anelva Co., Ltd. (72) Inventor Akihisa Matsuda 1-4-1 Umezono, Tsukuba, Ibaraki Pref. In-house (72) Inventor Michio Kondo 1-1-4 Umezono, Tsukuba, Ibaraki Pref. (Reference) 4K030 AA06 BA40 FA04 KA15 KA30 LA11 5F045 AA08 AB04 AC01 AD06 AE17 BB02 BB08 CA13 DA52 EH04 EH11 EH20 5F051 AA05 BA12 BA14 CA16 CA23 CA34 DA03 DA04 DA15

Claims (10)

[Claims] 1. A plurality of inductively coupled electrodes having a folded shape at the center and provided with a high-frequency power supply portion and a ground portion at both ends thereof are installed in parallel on the same plane, and the plurality of inductively coupled electrodes are provided. A high-frequency power is supplied to the mold electrode to generate a plasma, and a thin film is formed on a substrate disposed facing the inductive coupling-type electrode. A method for forming a thin film, characterized in that opposite feeding phases and AM modulation are performed at matching feeding parts. 2. The method of forming a thin film according to claim 1, wherein the frequency of the high frequency is changed so that a standing wave is generated between a feeding portion and a folded portion of the inductive coupling type electrode. 3. The thin film forming method according to claim 1, wherein in the AM modulation, a period in which high-frequency power is supplied and a period in which high-frequency power is shut off are alternately provided. 4. The thin film forming method according to claim 1, wherein a modulation frequency of the AM modulation is changed during the formation of the thin film. 5. The method according to claim 3, wherein a ratio of a period during which the high-frequency power is supplied is changed during the formation of the thin film. 6. A film forming chamber in which a plurality of inductively-coupled electrodes having a folded shape at the center and having a high-frequency power supply portion and a ground portion provided at both ends thereof are arranged in parallel on the same plane. A high-frequency power supply that supplies high-frequency power to the power supply unit;
Means for controlling the phase of the high-frequency power supplied to the power supply unit, and a waveform generator for performing AM modulation of the high-frequency power, wherein the high-frequency phases in adjacent power supply units of the plurality of inductively coupled electrodes are mutually It is characterized in that a high-frequency power having an opposite phase and AM modulation is supplied to the inductive coupling type electrode to generate plasma, and a thin film is formed on a substrate arranged facing the inductive coupling type electrode. Thin film forming equipment. 7. The thin film forming apparatus according to claim 6, wherein a distance between a feeding part and a folded part of the inductive coupling type electrode is a natural number times a half of the high frequency excitation wavelength. . 8. The structure according to claim 6, wherein said inductively coupled electrodes are arranged in a plurality of layers, substrates are arranged on both sides of each layer, and a thin film is formed on the plurality of substrates at the same time. 2. The thin film forming apparatus according to 1. 9. A solar cell comprising a thin film formed by the thin film forming method according to claim 1 as a constituent film. 10. A thin film containing at least one constituent element of the reactive gas by introducing a reactive gas into the thin film forming apparatus according to any one of claims 6 to 8, generating plasma. And a solar cell comprising the thin film as a constituent film.