JP2003068659A - Apparatus and method for plasma treatment, thin film produced by using the same, substrate, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of film thickness being made locally non-uniform by a strong electric field, since that strong electric field is generated between adjacent small electrodes when there is a phase difference between the high-frequency voltages of the adjacent small electrodes, even though film thickness distribution or distribution of an etching rate is improved by controlling the phase of the high-frequency voltage which is to be impressed to each of small electrodes, since a too large or too small electric field is generated close to a gap on each of small electrode surfaces by superimposing of a high-frequency impressed to each of small electrodes and it is not enouch to generate uniform plasma, when a high-frequency electrode is just divided into a plurality of small electrodes. SOLUTION: In the plasma treatment apparatus for impressing the high frequency voltage to a plurality of small electrodes comprising high frequency electrode, while shifting the phase of the high-frequency voltage, a size dc of the gap between the adjacent small electrodes can be controlled and the relation with a distance da between a plurality of small electrodes and a member to be treated is controlled to be within the range of 0.5<=dc/da<=3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus, a processing apparatus suitable for performing film deposition, etching or surface modification on a member to be processed, a processing method using this processing apparatus, and a processing method using these processing apparatuses. The present invention relates to a thin film, a substrate, and a semiconductor device manufactured by using a processing device or a processing method.

[0002]

2. Description of the Related Art Today, in semiconductor device manufacturing processes, processing such as thin film deposition, etching and surface modification using plasma energy is indispensable. In these plasma processing steps, liquid crystal displays and solar cells are used. It is important to increase the size of the semiconductor device such as the above, and to increase the area to be processed, the processing speed, and the processing quality in response to the demand for the improvement of the processing capacity.

The current state of such plasma processing will be described. Plasma CVD, which is a typical film deposition treatment method
Taking the method as an example, the deposited film is typically a polycrystalline silicon thin film, a microcrystalline thin film, or an amorphous thin film, and the silicon compound is a silicon oxide film, a silicon nitride film, or a metal silicide film. and so on. In order to improve mass productivity in the plasma CVD method, it is possible to increase the film forming rate by increasing the high frequency power or increasing the supply amount of the source gas. However, in the conventional method using the RF band high frequency of 13.56 MHz as the high frequency power, when film deposition is performed under such conditions, a large amount of powder is generated and the film quality due to the powder adhering to the member to be processed is It is difficult to realize a significant increase in the film-forming speed because it causes a decrease in the yield and a decrease in the yield.

As a solution to the problem of achieving both good film quality and high film forming speed, it is considered promising to increase the frequency of the applied voltage. It is known that the plasma temperature can be reduced and the plasma density can be improved at the same time by using a VHF band high frequency with an increased frequency.
It is expected that a high quality film can be deposited at a higher speed by using the HF band high frequency.

However, since the VHF band high frequency has a shorter wavelength than the RF band high frequency, it is known that the larger the maximum surface dimension of the high frequency electrode, the greater the influence of the standing wave generated on the electrode. As a result, the in-plane uniformity of the plasma density in the electrode is deteriorated, which causes the in-plane uniformity of the film thickness and the film characteristics in the case of film deposition, and the in-plane uniformity of the etching rate in the case of etching. I will end up. Further, as the frequency becomes higher, the influence of the stray capacitance becomes larger and the loss of the high frequency power other than between the electrodes becomes large, so that stable plasma generation becomes difficult. From these things, in the conventional device corresponding to the RF band high frequency, the VHF
It is practically difficult to perform a large area treatment using a high frequency band.

In view of these problems, a method for enabling large area processing by using VHF band high frequency is disclosed in Japanese Patent Laid-Open No. 2000-2.
It is disclosed in Japanese Patent No. 68994. The outline of the plasma CVD apparatus disclosed in Japanese Patent Laid-Open No. 2000-268994 will be described with reference to FIG. In the reaction container 4 provided with the gas introducing means 51 and the vacuum exhausting means 52, the high frequency power is applied from the high frequency power supply 1, the high frequency power is distributed after passing through the matching device 9, and the high frequency electrode 2 is divided into a plurality of parts.
High frequency power is applied to each of 1 to 24. By using such a high-frequency electrode divided into a plurality,
It says that uniform plasma generation is possible even in a large area.

[0007]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention
No. 000-268994,
A detailed study was conducted on the effect of the method of dividing the high frequency electrode into a plurality of parts. The inventors of the present invention have shown that, as shown in FIG.
Assume a high-frequency electrode consisting of four small electrodes 21 to 24 made of a cm square stainless steel flat plate and separated from each other by 12 mm, and further, each electrode is provided with an earth shield for preventing discharge on the side surface and the back surface. An electric field strength distribution was calculated by electromagnetic field calculation when high frequency power of 100 MHz was applied to each small electrode so as to have the same output and the same phase. At this time, the distance between the high frequency electrode and the member to be processed was 30 mm. Here, as shown in FIG.
The direction from the small electrode to the member to be processed is defined as the x direction, and x
Two directions, which are parallel to the small electrode surface orthogonal to the direction, are defined as ay direction and az direction. Electric field Ex in x direction obtained as a result of electromagnetic field calculation
The intensity distribution of is shown in FIG. As you can see from the curve in the figure,
The horizontal axis of FIG. 3 shows the position on the surface of the high-frequency electrode in the diagonal direction, and arrow a shows the size of the high-frequency electrode, and arrows b and c show the size of the small electrode. The vertical axis represents the electric field strength. A distribution in which the electric field becomes excessive near the center (A in FIG. 3) of the entire high-frequency electrode composed of a plurality of small electrodes occurs. It is considered that this is caused by the high-frequency folding applied to each small electrode. Conversely, B
As shown in the section, the electric field is too small in the gap between the small electrodes. This means that during plasma processing, excessive plasma is generated near the center (A part) with respect to the entire high-frequency electrode composed of a plurality of small electrodes, and near the gap between the small electrodes (B part).
It is predicted that an undersized plasma will be generated. It is clear that processing with such plasma causes problems in processing uniformity and quality. That is, in order to generate a uniform plasma, further improvement is required in addition to dividing the high frequency electrode into a plurality of parts.

Therefore, the inventors of the present invention adjust the phase of the high-frequency voltage applied to each small electrode to cancel the electric fields near the center (A portion) with respect to the entire high-frequency electrode composed of a plurality of small electrodes. By doing so, it was found that it is possible to obtain a substantially uniform electric field strength over the entire high frequency electrode. FIG. 4 shows the intensity distribution of the electric field Ex in the x direction when the phase of the high-frequency voltage applied to each small electrode is deviated, which is obtained by the present inventors through electromagnetic field calculation. The horizontal axis and the vertical axis in FIG. 4 are the same as those in FIG. As a condition for performing this calculation, it is assumed that the high frequency electrode shown in FIG.
For example, when 21 is selected, the phase of the high-frequency voltage applied to the second small electrodes 22 and 23 adjacent to the first small electrode 21 is relative to the phase of the high-frequency voltage applied to the first small electrode 21. Of the first small electrode 21 and the third small electrode 24 which is not adjacent to the first small electrode 21 and is adjacent to the second small electrodes 22 and 23. The phase of the high frequency voltage applied to the small electrode 21 is set to the same. An excessive electric field as shown in part A of FIG. 3 is suppressed, and by adjusting the phase of the high-frequency voltage applied to each small electrode, a more uniform plasma treatment can be performed on a member having a large area. It turned out to be possible. Further, as a result of performing the same examination by changing the phase shift variously, as a result, in order to suppress an excessive electric field as shown in A part of FIG. 3, it is necessary to shift the phase of the high frequency voltage applied to the adjacent small electrode. Was preferable, and it was found that a uniform electric field intensity distribution can be obtained on each small electrode surface as shown in FIG.

In order to investigate the correlation between the uniform electric field distribution shown in FIG. 4 and the actual film thickness distribution, a film forming experiment was conducted. The film thickness distribution obtained as a result is shown in FIG. The horizontal axis of FIG. 5 is shown in FIG.
Is the same as that shown in, and the vertical axis shows the film thickness distribution. The film thickness of the portion corresponding to the small electrode surface showed a uniform distribution similar to the calculation result of FIG. 4, but B corresponding to the gap of each small electrode
In the portion, although it was predicted from the result of FIG. 4 that the electric field was small, the film thickness was decreased, but the film thickness tended to be increased.

Therefore, a Langmuir probe is inserted from the port of the reaction vessel between the high frequency electrode and the member to be treated,
The result of measuring the plasma electron density distribution is shown in FIG. The horizontal axis of FIG. 6 is the same as that shown in FIG. 3, and the vertical axis shows the electron density. As shown in FIG. 6, it was found that the electron density was high in the portion B corresponding to the gap between the small electrodes.

Therefore, not only the electric field Ex in the x direction, but also the electric field Ey in the y direction and the electric field E in the z direction parallel to the respective small electrodes.
of the electric field E = (Ex ² + Ey ² + Ez ² ) ^1/2 including z
FIG. 7 shows the in-plane distribution at a position 3 mm away from the main surface of the small electrode on the side of the member to be processed under the same conditions as in FIG. It was found that the electric field E in FIG. 7 was rather strong in the B portion corresponding to the gap between the small electrodes. When there is a phase difference in the high-frequency voltage applied between the adjacent small electrodes, a potential difference occurs between the adjacent small electrodes, so that in a region near the small electrode in the gap portion such as the region C shown in FIG. It is considered that this is because an electric field between adjacent small electrodes (electric field in the y or z direction parallel to the small electrode surface) is generated. As a result, it is considered that the film thickness at the portion corresponding to the gap between the small electrodes was increased.

The present invention has been made in view of the above problems, and makes it possible to increase the area to be processed, improve the processing speed, and improve the processing quality in response to the increase in the size of semiconductor devices and the improvement in processing capacity. A plasma processing apparatus and a plasma processing method, and a thin film, a substrate, and a semiconductor device manufactured by using the plasma processing apparatus.

[0013]

The first aspect of the present invention comprises:
In the reaction vessel, an electrode divided into a plurality of small electrodes,
A plasma is generated by applying a high-frequency power whose phase is shifted from a high-frequency power source to an electrode that is provided with a member-to-be-processed portion and is divided into a plurality of small electrodes, and the member-to-be-processed is processed. In the plasma processing apparatus, the size of the gap between adjacent small electrodes is adjustable.

A second aspect of the present invention is an electrode divided into a plurality of small electrodes, which comprises an electrode divided into a plurality of small electrodes and a member disposition portion to be treated in a reaction vessel. In a device for generating plasma by applying high-frequency power whose phase is shifted from a high-frequency power source to perform processing on a member to be processed, a size dc of a gap between adjacent small electrodes,
The plasma processing apparatus is characterized in that the distance da between the plurality of small electrodes and the member to be processed has a relationship of 0.5 ≦ dc / da ≦ 3.

According to a third aspect of the present invention, in the plasma processing apparatus of the first and second aspects, the phase shift of the high frequency voltage applied to the small electrodes adjacent to each other is 120 to 24.
It is a plasma processing method characterized by adjusting so as to be in a range of 0 degree.

In a fourth aspect of the present invention, the frequency is 20-5.
Plasma CVD using high frequency in the range of 00MHz
By the method, it is a thin film deposited on a substrate having a maximum dimension of 1 m or more and having a film thickness distribution within 10%.

A fifth aspect of the present invention is a substrate having the thin film of the fourth aspect formed on at least one main surface.

A sixth aspect of the present invention is a semiconductor device manufactured using the thin film of the fourth aspect or the substrate of the fifth aspect.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION When electric power of the same phase is applied to electrodes divided into a plurality of small electrodes, an electric field is not generated in the gaps between the small electrodes, so that the plasma treatment in the gaps becomes uneven. Occurs. Therefore, by making the gap as small as possible, the electric field drop in the gap is suppressed,
It is common to prevent non-uniformity in plasma processing.

On the other hand, when there is a phase difference in the high-frequency voltage applied between the adjacent small electrodes, a potential difference occurs between the adjacent small electrodes in the gap portion, so that the gap between the adjacent small electrodes is as shown in FIG. In a region close to the small electrode, such as the C region, an electric field in the y or z direction parallel to the small electrode surface is generated between the adjacent small electrodes. Therefore, if the size of the gap between the adjacent small electrodes is made too small, the electric field between the adjacent small electrodes becomes too strong, resulting in non-uniform plasma. Therefore, it is necessary to adjust the magnitude of the electric field applied between the adjacent small electrodes so that the plasma treatment becomes uniform.

The electric field distribution that greatly affects the uniformity of the plasma treatment depends on the magnitude of the electric field applied between the adjacent small electrodes and
It is determined by the magnitude of the electric field applied between the small electrode and the member to be processed. The electric field applied between the adjacent small electrodes is related to the size of the gap between the adjacent small electrodes. On the other hand, the magnitude of the electric field applied between the small electrode and the member to be processed is related to the distance between the small electrode and the member to be processed.

Therefore, the relationship between the size of the gap between the adjacent small electrodes and the distance between the plurality of small electrodes and the member to be processed becomes important. Specifically, when the size of the gap between the adjacent small electrodes is too small as compared with the distance between the plurality of small electrodes and the member to be processed, the electric field applied between the small electrodes and the member to be processed is smaller than that. The electric field between the adjacent small electrodes becomes too strong, and the plasma is excessively generated in the gap, so that the plasma treatment becomes nonuniform. On the contrary, if the size of the gap between the adjacent small electrodes is too large as compared with the distance between the plurality of small electrodes and the member to be processed, the electric field applied between the small electrodes and the member to be processed is larger than that. The electric field between adjacent small electrodes becomes too weak, and the amount of plasma generated in the gap is too small, resulting in non-uniform plasma treatment.

Therefore, the plasma processing is made uniform by adjusting the size of the gap between the adjacent small electrodes in accordance with the plasma generation conditions and the size of the electric field applied between the adjacent small electrodes. Made possible.

When a phase difference is given to the electric power applied to the plurality of small electrodes, the size dc of the gap between the adjacent small electrodes
And the distance da between the plurality of small electrodes and the member to be processed is 0.
By satisfying the relationship of 5 ≦ dc / da ≦ 3, it is possible to obtain a good film thickness distribution.

Further, in order to improve the uniformity of the plasma treatment, it is more preferable that the phase shift of the high-frequency voltage applied to the small electrodes adjacent to each other is in the range of 120 to 240 degrees. In this case, since the phase difference is large and the potential difference between the adjacent electrodes is large, the gap size dc between the adjacent small electrodes and the distance da between the plurality of small electrodes and the member to be processed are 0. It is more desirable to have a relationship of 0.7 ≦ dc / da ≦ 2.

In order to carry out high-quality plasma treatment, the thin film to be formed is less ion-damaged, for example,
Under a process condition of a pressure of 200 Pa or more and 2000 Pa or less, when a phase difference is applied to the electric power applied to the plurality of small electrodes, the reaction is frequently caused due to the high pressure, and the mean free path of the particles becomes small, It is appropriate that the size of the gap between the adjacent small electrodes is smaller, and the size dc of the gap between the adjacent small electrodes and the distance da between the plurality of small electrodes and the member to be processed are 0.5. In the case of ≦ dc / da ≦ 2, the uniformity of plasma processing is improved. In order to further improve the uniformity of the plasma treatment, the phase shift of the high frequency voltage applied to the small electrodes adjacent to each other should be 12%.
It is preferably in the range of 0 to 240 degrees. In this case, since the phase difference is large and the potential difference between the adjacent electrodes is large, the gap size dc between the adjacent small electrodes and the distance da between the plurality of small electrodes and the member to be processed are 0. 7 ≦
More preferably, the relationship of dc / da ≦ 1.5 is satisfied.

The size of the gap between adjacent small electrodes is substantially the distance between the small electrodes to which a high frequency is applied, and a dielectric or a ground shield is installed so as to surround each small electrode. Even in the case where the dielectric is filled between the adjacent small electrodes, the distance is a distance between the small electrodes to which a high frequency is substantially applied, as in the distance D shown in FIG.

In the plasma processing apparatus of the present invention, the maximum size of each small electrode is set to 1 of the wavelength of the applied high frequency.
By setting the ratio to / 4 or less, it is possible to prevent a standing wave from being generated on each small electrode surface, so that it is possible to perform more uniform plasma processing on a member to be processed having a large area. The maximum size of the substrate means the size of the position where the distance between any two points on the surface of the substrate is the maximum. For example, the diagonal length is for a rectangular flat plate, and the diameter is for a disc. Equivalent to.

Further, as a result of variously changing the phase shift, in order to suppress an excessive electric field as shown in the portion A of FIG. 3, the phase of the high frequency voltage applied to the adjacent small electrode is set to 12.
The offset within the range of 0 to 240 degrees is suitable for improving the uniformity of plasma treatment.

By setting the frequency of the high frequency voltage applied to each small electrode in the range of 20 to 500 MHz, the electron density in the plasma can be increased and the plasma potential can be suppressed to a low level, so that the processing speed can be increased. And the processing quality can be improved at the same time.

A plasma processing apparatus and a plasma processing method according to the present invention are used for film deposition in a semiconductor device manufacturing process,
In plasma processing such as etching and surface modification,
The area to be processed can be increased, the processing speed can be improved, and the processing quality can be improved in response to the improvement in processing capacity. A semiconductor device manufactured by using the device or method can be manufactured at high performance and at low cost. Has the advantage.

An embodiment of the present invention will be described below with reference to a plasma CVD apparatus having a high frequency electrode which is divided into a plurality of rectangular small electrodes and ladder small electrodes and which are arranged in a flat plate shape. However, the present invention is not limited thereby. For example, the shape of the small electrodes is not limited to the square shape, but may be a rod shape, a disc shape, a spherical shape, or the like, and the arrangement of each small electrode is not limited to the flat shape, but a lattice shape or a concentric shape. And so on. Further, the plasma treatment is not limited to film deposition, but etching or the like can similarly improve the treatment quality. (Examples 1 to 5 and Comparative Example 1) FIG. 1 is a schematic sectional view of the plasma CVD apparatus used in this example. Inside a stainless steel reaction vessel 4 equipped with a gas introduction means 51 and a vacuum exhaust means 52, a flat plate-shaped high-frequency electrode divided into a plurality of small electrodes 21 to 24 and stainless steel on which a member 3 to be processed is placed. The processed member disposing portion 31 made of steel is disposed so as to be parallel to each other. The processing member disposing portion 31 made of stainless steel on which the reaction container 4 and the processing target member 3 are placed is electrically grounded. On the other hand, a plurality of small electrodes 2
The high-frequency electrode divided into 1 to 24 is electrically insulated from the reaction container 4. FIG. 2 shows a perspective view of the high frequency electrodes 21 to 24. Each small electrode is a 50 cm square stainless steel flat plate, and these are arranged so as to have a square shape as a whole to form a flat plate-shaped high frequency electrode. In order to prevent abnormal discharge on the side surface and the back surface of the small electrode, ground shields 61 to 64 made of a stainless steel plate were installed so as to surround the side surface and the back surface of each small electrode. Further, in order to adjust the size of the gap between the adjacent small electrodes, horizontal movement mechanisms 71 to 74 capable of horizontally moving diagonally toward the center of the entire high frequency electrode are provided for each small electrode. It was Further, in order to adjust the distance between the member to be processed and the small electrode, a vertical moving mechanism 8 which is movable in the vertical direction is provided in the member to be processed arrangement portion. Horizontal movement mechanism 71-7
4. The vertical movement mechanism 8 is a mechanism that can be manually moved without breaking the vacuum by the high vacuum linear introduction terminal. The high-vacuum linear introduction terminal is a terminal that introduces a linear motion from the atmosphere side into a vacuum container in a high vacuum.By rotating the handle on the atmosphere side and converting the rotation into a linear motion by a gear, It has a mechanism to scroll the vacuum side axis.

The high frequency oscillated from the high frequency power source 1 is distributed by the distributor 9 to the four high frequency transmission lines, and the power monitors 101 to 101 provided for the respective high frequency transmission lines.
104, matching devices 111 to 114, and phase adjuster 121 to
It is applied to each of the small electrodes 21 to 24 via 124.
The phase adjusters 121 to 124 for varying the phase of the high frequency voltage applied to each of the small electrodes 21 to 24 are electric circuits composed of inductance and capacitance. The power monitor 1 provided for each of the small electrodes 21 to 24
By reading the values of 01 to 104 and adjusting them by the matching devices 111 to 114, the high frequency power applied to each of the small electrodes 21 to 24 is adjusted.

In this example, an amorphous silicon thin film was formed by using monosilane and hydrogen as source gases. The main film forming conditions are as follows.

Member to be treated: glass substrate (1 m square) Total gas flow rate: SiH ₄ 1300 sccm H ₂ 1800 sccm Substrate temperature: 200 ° C. High frequency power: 0.2 Wcm ^-2 Frequency: 100 MHz Pressure: 30 Pa In FIG. The waveform diagram of the high frequency voltage applied to 24 is shown. The high frequency voltages applied to the small electrode 21 and the small electrode 24 have the same phase. Further, the high frequency voltages applied to the small electrode 22 and the small electrode 23 have the same phase. And the small electrode 21
The phase difference between the high-frequency voltage applied to the small electrode 24 and the voltage applied to the small electrode 22 and the small electrode 23 is 30, 6
The angles are shifted to 0, 120, 135 and 180 degrees. At this time, the high frequency power applied to each of the small electrodes 21 to 24 was adjusted to be the same. The high frequency voltage applied to the small electrode 21 and the small electrode 24, and the small electrode 22 and the small electrode 23.
The phase difference of 30 degrees from the voltage applied to the first embodiment, 60 degrees in the second embodiment, 120 degrees in the third embodiment, 135 degrees in the fourth embodiment,
Example 5 is 180 degrees.

The vertical moving mechanism 8 set the distance between the small electrode and the member to be processed to 30 mm, and the horizontal moving mechanisms 71 to 74 adjusted the size of the gap between the small electrodes.

After the film forming process for 1 hour, the glass substrate on which the amorphous silicon thin film was deposited was taken out from the reaction container 4,
The glass substrate was cut into 9 equal parts in the vertical and horizontal directions to produce 81 film thickness measurement samples. By equally dividing into odd numbers and measuring the film thickness at the center using a step gauge, it is possible to perform a comparative evaluation of the film thickness on the small electrode surface and the film thickness immediately above the gap between each small electrode. did. Note that (maximum value-minimum value) / (maximum value + minimum value) of 81 samples
Was calculated as the film thickness distribution.

FIG. 10 shows the film thickness distribution when the size of the gap between the small electrodes is changed by the horizontal moving mechanisms 71 to 74. The horizontal axis of FIG. 10 shows the relationship of dc / da of the distance da between the small electrode and the member to be processed, and the vertical axis shows the film thickness distribution. In addition, for comparison, the high-frequency voltage applied to the small electrodes 21 to 24 has the same phase and the other conditions are exactly the same as those of Examples 1 to 5, and the film thickness distribution of Comparative Example 1 is also shown in FIG. . Here, the phase difference is from 0 degree (the same phase) to 180
The phase difference is changed in the range of 0 degrees to 360 degrees in consideration of the symmetry of the phase difference.

From the results of FIG. 10, the size dc of the gap between the adjacent small electrodes and the distance da between the plurality of small electrodes and the member to be processed are in the relationship of 0.5 ≦ dc / da ≦ 3. At times, the film thickness distribution can be reduced as compared with the case where high frequency power is applied in the same phase.

In particular, when the retardation is in the range of 120 ° to 180 °, a film having a film thickness distribution within 10% can be obtained. Considering the symmetry of the phase difference, it is preferable that the phase difference is in the range of 120 degrees to 240 degrees in order to obtain a more uniform film.

Furthermore, when the phase difference is in the range of 120 to 180 degrees, and in consideration of the symmetry of the phase difference, in the range of 120 to 240 degrees, the distance da between the plurality of small electrodes and the member to be processed is da.
And the size dc of the gap between the adjacent small electrodes is 0.7 ≦
When dc / da ≦ 2, a more uniform film with a film thickness distribution within 10% can be obtained. (Examples 6 to 10 and Comparative Example 2) Vertical movement mechanism 8
The distance between the plurality of small electrodes and the member to be processed is 20 mm,
The film was formed under the same conditions as in Example 1 except that the pressure was set to 200 Pa, and Example 6 was followed, and those having the same phase difference as Examples 2 to 5 below were taken as Examples 7 to 10. Example 6
The film thickness distribution of 10 to 10 was evaluated. Further, for comparison, the high frequency voltage applied to the small electrodes 21 to 24 has the same phase and the other conditions are exactly the same as in Example 6, and the film thickness distribution of Comparative Example 2 formed is also shown in FIG.

From the result of FIG. 11, when the pressure is 200 Pa, the size dc of the gap between the adjacent small electrodes and the distance da between the plurality of small electrodes and the member to be processed are 0.5 ≦ dc.
When / da ≦ 2, the film thickness distribution is reduced as compared with the case where high frequency power is applied in the same phase.

When the pressure is 200 Pa, a film having a film thickness distribution of 10% or less is obtained when the phase difference is in the range of 120 ° to 180 °. Considering the symmetry of the phase difference, the phase difference Is preferably in the range of 120 degrees to 240 degrees in order to obtain a more uniform film.

Further, when the pressure is 200 Pa, when the phase difference is in the range of 120 to 180 degrees, that is, in the range of 120 to 240 degrees in consideration of the symmetry of the phase difference,
The distance da between the plurality of small electrodes and the member to be processed and the size dc of the gap between the adjacent small electrodes are 0.7 ≦ dc / da ≦.
In the range of 1.5, a more uniform film having a film thickness distribution within 10% can be obtained. (Examples 11 to 20 and Comparative Examples 3 and 4) The distance between the plurality of small electrodes and the member to be processed is set to 15 by the vertical movement mechanism 8.
mm, the pressure was 500 Pa, and other than that, Example 1
The film formed under the same conditions as in Example 11 was referred to as Example 11, and the films having the same retardation as Examples 2 to 5 below were referred to as Examples 12 to 15 in order. The film thickness distributions of Examples 11 to 15 were evaluated. Also,
For comparison, the high-frequency voltage applied to the small electrodes 21 to 24 has the same phase and the other conditions are exactly the same, and the film thickness distribution of Comparative Example 3 formed is also shown in FIG.

The distance between the plurality of small electrodes and the member to be processed is set to 7 mm by the vertical movement mechanism 8 and the pressure is set to 2,000 P.
The film was formed under the same conditions as in Example 1 except that a was formed as a, and Example 16 was made in the same manner as in Example 1 and those having a phase difference similar to those in Examples 2 to 5 were made in order to Examples 17 to 20. The film thickness distributions of Examples 16 to 20 were evaluated. Also, the high-frequency voltage applied to the small electrodes 21 to 24 has the same phase and the other conditions are exactly the same as those shown in FIG.

From the results shown in FIGS. 12, 13 and 11,
As the pressure increases, the size dc of the gap between adjacent small electrodes is divided by the distance da between the plurality of small electrodes and the member to be processed, which is dc / da. Also, the upper limit of the range in which the film thickness distribution can be reduced becomes smaller. Therefore, the pressure is 200 Pa or more and 2,000
At 0 Pa or less, the film thickness distribution can be reduced in the range of 0.5 ≦ dc / da ≦ 2.

Further, the pressure is 200 Pa or more and 2000 Pa.
In the following cases, when the phase difference is in the range of 120 degrees to 180 degrees, a film having a film thickness distribution of 10% or less is obtained, and considering the symmetry of the phase difference, it is in the range of 120 degrees to 240 degrees. However, it is preferable to obtain a film having good uniformity.

Further, the pressure is 200 Pa or more and 2000 P
In the case of a or less, when the phase difference is in the range of 120 degrees to 180 degrees, that is, 120 degrees to 2 in consideration of the symmetry of the phase difference.
In the range of 40 degrees, the relationship between the distance da between the plurality of small electrodes and the member to be processed and the size dc of the gap between the adjacent small electrodes is in the range of 0.7 ≦ dc / da ≦ 1.5. When
A film having a uniform film thickness distribution of 10% or less can be obtained. (Examples 21 to 25 and Comparative Example 5) 50 cm square stainless steel flat plate small electrodes 21 to 24 used in Example 1
In place of the above, as shown in FIG. 14, small electrodes 25 to 28 were used which were obtained by welding a rectangular rod-shaped member made of stainless steel and processed into a ladder shape. The outer shape of the ladder-type small electrode was 50 cm square, the thickness of the rectangular rod-shaped member was 19 mm, and the gap between the adjacent rod-shaped members was 18 mm. The film formed under the same conditions as in Example 1 was set as Example 21, and the films having the same phase difference as those in Examples 2 to 5 were set as Examples 22 to 25 in this order. Examples 21 and 2
The film thickness distribution of No. 5 was evaluated. Further, FIG. 15 also shows the film thickness distribution of Comparative Example 5 in which the high-frequency voltage applied to the small electrodes 25 to 28 processed into the ladder shape has the same phase and the other conditions are exactly the same.

From the result of FIG. 15, a plurality of small electrode shapes are
Even if it was a ladder type instead of a flat plate, the same result as that of the flat plate was obtained.

In each of the above-described embodiments, four small square electrodes or ladder-shaped small electrodes each having a size of 50 cm square are arranged side by side, but the shape is rectangular or polygonal. It may have various shapes such as a circular shape, and when the maximum size of each small electrode is ¼ or less of the wavelength of the applied high frequency voltage, a particularly remarkable effect is obtained. Further, in the present example, by changing the size dc of the gap between the adjacent small electrodes and the distance da between the plurality of small electrodes and the member to be processed, the size dc of the gap between the adjacent small electrodes is changed. dc
Although / da is adjusted, it is also possible to adjust dc / da by changing the distance da between the plurality of small electrodes and the member to be processed. (Example 26) In this example, a thin film solar cell was produced by forming a photoelectric conversion layer made of an amorphous silicon thin film using the plasma CVD apparatus shown in FIG. FIG. 16 shows a schematic cross-sectional view of the thin-film solar cell manufactured in this example. A glass substrate 80 cm square and 1.1 mm thick was used as the substrate 131, and ZnO was formed thereon as the transparent electrode 132 by a sputtering method so as to have a film thickness of about 1 μm. Then, the substrate 13 is placed so that the side on which the transparent electrode 132 is formed faces the high frequency electrode composed of a plurality of small electrodes.
1 is loaded into the reaction vessel of the plasma CVD apparatus shown in FIG. A p-type amorphous silicon thin film 133 having a film thickness of 30 nm, an i-type amorphous silicon thin film 134 having a film thickness of 300 nm, and an n-type amorphous silicon thin film 135 having a film thickness of 30 nm are sequentially formed on the transparent electrode 132. Thus, the photoelectric conversion layer was formed. The film forming conditions for the p-type, i-type, and n-type amorphous silicon thin films are shown below. The frequency of the applied high frequency is 100 MHz in any case, and the phase shift of 135 degrees shown in FIG. 9 is caused with respect to the high frequency voltage applied to each of the small electrodes 21 to 24. Further, the vertical movement mechanism 8 set the distance between the small electrodes and the member to be processed to 30 mm, and the horizontal movement mechanisms 71 to 74 adjusted the size of the small electrode gap to 40 mm. Film-forming conditions for p-type amorphous silicon thin film High frequency power: 0.05 W / cm ² Source gas: SiH ₄ 150 sccm H ₂ 1500 sccm B ₂ H ₆ (2.0% / H ₂ ) 300 sccm Pressure: 30 Pa Substrate temperature: 200 ℃ Distance between small electrode and member to be treated: 30 mm Size of gap between multiple small electrodes: 40 mm Film forming conditions for i-type amorphous silicon thin film High frequency power: 0.2 W / cm ² Source gas: SiH ₄ 600SCCM H ₂ 900 SCCM Pressure: 30 Pa Substrate temperature: 200 ° C. Distance between small electrode and member to be processed: 30 mm Gap size between multiple small electrodes: 40 mm Film forming conditions for n-type amorphous silicon thin film High frequency power: 0.04 W / cm ² source _{gas: SiH 4 100sccm H 2 1200sccm PH} 3 (2.0% / H 2) 100sccm pressure: 30 Pa substrate temperature: 200 ° C. small The distance between the pole To the member to be processed: 30mm plurality small electrode gap size: After removing the substrate 131 from 40mm reaction vessel, the back electrode 13
As No. 6, Ag was formed by sputtering to have a thickness of 300 nm. The back electrode 136 also has a role of improving the power generation efficiency by reflecting the light that has once passed through the photoelectric conversion layer.

9 × 9 unit cells (4 cm square) were prepared for each glass substrate, and the distribution of photoelectric conversion efficiency was measured. FIG. 17 shows the variation when the average value of the photoelectric conversion efficiencies in the 81 unit cells is 1. (Comparative Example 6) Using the plasma CVD apparatus shown in FIG. 19, high frequency power is applied to a plurality of small electrodes in the same phase, and the vertical movement mechanism 8 sets the distance between the small electrodes and the member to be processed to 30 mm. In the case where the film was formed under the same film forming conditions as in Example 6, except that the size of the gap between the small electrodes was adjusted to 6 mm by the horizontal movement mechanisms 71 to 74.
Fig. 1 shows the variation in the photoelectric conversion efficiency in each unit cell.
8 shows.

The variation in photoelectric conversion efficiency of the thin film solar cell produced by using the plasma CVD apparatus of the present invention is small,
It was confirmed that the yield can be improved by the plasma CVD apparatus and the plasma CVD method of the present invention.

In this example, the plasma CVD apparatus and the plasma CVD method of the present invention were applied to the manufacturing process of a thin film solar cell using an amorphous silicon thin film as a photoelectric conversion layer, but the effect of the present invention is not limited to this. Absent. For example, in forming a polycrystalline silicon thin film or etching an amorphous silicon thin film or a polycrystalline silicon thin film, the area to be processed is increased and the processing speed is increased in response to the increase in the size of the semiconductor device and the improvement in the processing capacity. , And improvement of processing quality are possible,
It goes without saying that the present invention improves yield, reliability, and mass productivity in plasma processing steps such as film deposition and etching. However, it goes without saying that the present invention can be applied not only to the manufacturing process of thin film solar cells but also to the manufacturing process of thin film transistors and the like.

[0054]

According to the present invention, the size dc of the gap between adjacent small electrodes is adjusted in a plasma processing apparatus which applies a high frequency voltage with a phase difference shifted to a plurality of small electrodes constituting the high frequency electrode. And the relationship between the distance da between the plurality of small electrodes and the member to be processed is 0.5 ≦ dc / da ≦
By adjusting the range to 3, the film thickness distribution and the etching rate distribution are improved.

Therefore, according to the present invention, in a plasma processing step such as a film forming step and an etching step in a semiconductor device manufacturing process, an area to be processed is increased and a processing speed is increased in response to an increase in size of a semiconductor device and an increase in processing capability. It is possible to improve the processing quality, and as a result, the yield,
It is possible to improve reliability and mass productivity.

[Brief description of drawings]

FIG. 1 shows a schematic cross-sectional view of a plasma CVD apparatus that is one embodiment of the present invention.

FIG. 2 is a schematic perspective view of divided small electrodes for applying a high frequency voltage in a plasma CVD apparatus.

FIG. 3 is a diagram showing an intensity distribution of an electric field from a small electrode on a high frequency electrode surface toward a member to be processed in a conventional plasma CVD method.

FIG. 4 is a diagram showing an intensity distribution of an electric field from a small electrode on a surface of a high frequency electrode in a plasma CVD apparatus in which a high frequency voltage is applied with a phase shift;

FIG. 5 is a diagram showing a film thickness distribution of a sample deposited in a plasma CVD apparatus in which a high frequency voltage is applied with a phase shift.

FIG. 6 is a diagram showing a plasma electron density distribution in a plasma CVD apparatus in which a high frequency voltage is applied with a phase shift.

FIG. 7 is a diagram showing an electric field intensity distribution on a high-frequency electrode surface in a plasma CVD apparatus that applies a high-frequency voltage with a shifted phase.

FIG. 8 shows a schematic cross-sectional view of a plasma CVD apparatus.

FIG. 9 shows a waveform diagram of a high-frequency voltage applied to each small electrode.

FIG. 10 shows dc / according to Examples 1 to 5 and Comparative Example 1.
The correlation diagram of da and film thickness distribution is shown.

FIG. 11: dc according to Examples 6 to 10 and Comparative Example 2
The correlation diagram of / da and film thickness distribution is shown.

FIG. 12 d according to Examples 11 to 15 and Comparative Example 3
The correlation diagram of c / da and film thickness distribution is shown.

FIG. 13 d according to Examples 16 to 20 and Comparative Example 4
The correlation diagram of c / da and film thickness distribution is shown.

FIG. 14 is a schematic perspective view of a divided ladder type small electrode for applying a high frequency voltage in the plasma CVD apparatus.

FIG. 15 d according to Examples 21 to 25 and Comparative Example 5
The correlation diagram of c / da and film thickness distribution is shown.

FIG. 16 shows a schematic cross-sectional view of a thin film solar cell that is a semiconductor device of the present invention.

FIG. 17 shows variations in photoelectric conversion efficiency in a thin film solar cell manufactured by the plasma CVD method of the present invention.

FIG. 18 shows variations in photoelectric conversion efficiency in a thin film solar cell manufactured by a conventional plasma CVD method.

FIG. 19 shows a schematic sectional view of a conventional plasma CVD apparatus.

[Explanation of symbols]

1 ... High frequency power supply 21-24 ... Small electrodes 25-28 ... Ladder type small electrode 3 ... Treated member 31 ... Arrangement part for processed member 4 ... Reaction vessel 51 ... Gas introduction means 52 ... Evacuation means 61-64 ... Earth shield made of stainless steel 71-74 ... Horizontal movement mechanism 8 ... Vertical movement mechanism 9 ... Distributor 101-104 ... Electric power monitor 111-114 ... Matching device 121-124 ... Phase adjuster 131 ... Glass substrate 132 ... Transparent electrode 133 ... p-type amorphous silicon 134 ... i-type amorphous silicon 135 ... n-type amorphous silicon 136 ... Back electrode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Haruki Morita             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Naoshi Hayakawa             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F-term (reference) 4K030 AA06 AA17 BA30 CA06 FA03                       JA01 JA03 JA09 JA18 JA19                       KA30 LA16                 5F045 AA08 AB04 AC01 AD06 AE19                       AF07 BB02 BB09 BB15 CA13                       CA15 DP05 EH04 EH06 EH07                       EH14 EH20                 5F051 AA05 BA14 CA02 CA03 CA04                       CA07 CA15 CA26 CA34 CA40                       DA04 FA02

Claims (14)

[Claims] 1. A reaction vessel comprising an electrode divided into a plurality of small electrodes and a member-to-be-treated arrangement portion, and the electrode divided into the plurality of small electrodes is out of phase with a high frequency power source. A plasma processing apparatus in which plasma is generated by applying high-frequency power to perform processing on a member to be processed, wherein a size of a gap between adjacent small electrodes is adjustable. 2. A reaction container is provided with an electrode divided into a plurality of small electrodes and a member disposition part to be treated, and the electrode divided into the plurality of small electrodes is shifted in phase from a high frequency power source. In a device that generates plasma by applying high-frequency power to perform processing on a member to be processed, a size dc of a gap between adjacent small electrodes and a distance between the plurality of small electrodes and the member to be processed. A plasma processing apparatus, wherein da has a relationship of 0.5 ≦ dc / da ≦ 3. 3. The plasma processing apparatus according to claim 1, wherein the phase shift of the high-frequency voltage applied to the small electrodes adjacent to each other is in the range of 120 to 240 degrees. 4. The size d of the gap between the adjacent small electrodes.
4. The plasma processing apparatus according to claim 3, wherein c and a distance da between the plurality of small electrodes and the member to be processed have a relationship of 0.7 ≦ dc / da ≦ 2. 5. Under a process condition where the pressure is 200 Pa or more and 2000 Pa or less, the size dc of the gap between the adjacent small electrodes and the distance da between the plurality of small electrodes and the member to be processed are 0.5 ≦ dc. The plasma processing apparatus according to claim 1 or 2, wherein the relationship is / da ≦ 2. 6. The plasma processing apparatus according to claim 5, wherein the phase shift of the high frequency voltage applied to the adjacent small electrodes is in the range of 120 to 240 degrees. 7. The size d of the gap between the adjacent small electrodes.
7. The plasma processing apparatus according to claim 6, wherein c and a distance da between the plurality of small electrodes and the member to be processed have a relationship of 0.7 ≦ dc / da ≦ 1.5. 8. The plasma processing apparatus according to claim 1, wherein the maximum size of each of the small electrodes is ¼ or less of the wavelength of the high frequency. 9. Using a high frequency having a frequency in the range of 20 to 500 MHz on a substrate having a maximum dimension of 1 m or more,
A thin film having a film thickness distribution within 10% is deposited.
9. The plasma device according to any one of 8. 10. The plurality of small electrodes in the plasma processing apparatus according to claim 1, wherein a phase shift of a high frequency voltage applied to adjacent small electrodes is 120 to 120.
A plasma processing method, wherein the range is 240 degrees. 11. The plasma processing method according to claim 1, wherein the frequency of the high frequency applied to the small electrodes adjacent to each other is 20 MHz to 500 MHz. 12. The plasma processing apparatus according to claim 1, wherein the maximum dimension is 1 by a plasma CVD method using a high frequency having a frequency in the range of 20 to 500 MHz.
A thin film having a film thickness distribution within 10%, deposited on a substrate having a thickness of m or more. 13. A substrate having the thin film according to claim 12 formed on at least one main surface. 14. A semiconductor device manufactured using the thin film according to claim 12 or the substrate according to claim 13.