WO2010079740A1

WO2010079740A1 - Plasma processing apparatus

Info

Publication number: WO2010079740A1
Application number: PCT/JP2010/000028
Authority: WO
Inventors: 若松貞次; 亀崎厚治; 菊池正志; 神保洋介; 江藤謙次; 浅利伸; 内田寛人
Original assignee: 株式会社アルバック
Priority date: 2009-01-09
Filing date: 2010-01-05
Publication date: 2010-07-15
Also published as: DE112010000818T8; CN102272893A; TW201034526A; KR101303968B1; DE112010000818T5; KR20110089457A; JPWO2010079740A1

Abstract

Disclosed is a plasma processing apparatus which comprises: an electrode flange (4); a chamber (2) having an inner wall surface (34); an insulating flange (31) arranged between the electrode flange (4) and the chamber (2); a base member (3) which has a lateral surface (32) and is arranged within the chamber (2), and on which a substrate (10) is placed; an RF power supply (9) which is connected to the electrode flange (4) and applies a high-frequency voltage thereto; and insulating members (41, 42) which are arranged on at least either the lateral surface (32) of the base member (3), which faces the inner wall surface (34), or the inner wall surface (34), which faces the lateral surface (32) of the base member (3).

Description

Plasma processing equipment

The present invention relates to a plasma processing apparatus.
This application claims priority based on Japanese Patent Application No. 2009-004027 filed on Jan. 9, 2009, the contents of which are incorporated herein by reference.

2. Description of the Related Art Conventionally, a plasma CVD apparatus that decomposes a source gas using plasma and forms a thin film on a substrate is known (see, for example, Patent Document 1). When a solar cell, particularly a solar cell using microcrystal silicon (μc-Si), is manufactured using this plasma CVD apparatus, it is necessary to increase the deposition rate from the viewpoint of productivity.
In order to increase the deposition rate, a high-pressure depletion method is effective in a state where the distance between the shower plate surface for ejecting deposition gas to the substrate surface and the substrate surface is narrow (narrow gap).
On the other hand, a plasma CVD apparatus is indispensable for manufacturing LCDs or solar cells. As the size of the substrate increases, the size of the device also increases. As the substrate area increases, the high-frequency power supplied to the apparatus also increases, and further, high-rate film formation by narrow gap discharge is necessary, so that it is necessary to pass a large current through the apparatus.
For example, as shown in FIG. 4, in the conventional plasma CVD apparatus 100, a substrate 110 is placed on a base member 103, and a film formation surface (surface) of the substrate 110 and a surface of the shower plate 105 are opposed to each other. In this state, a film is formed on the substrate 110. At this time, since the potential of the base member 103 needs to be the ground potential, a ground plate 130 is provided between the base member 103 and the chamber 102, and a film is formed on the substrate 110 with the chamber 102 grounded. ing.

JP 2008-244079 A

By the way, in the conventional plasma CVD apparatus 100, the side surface 132 of the base member 103 and the inner wall surface 134 of the chamber 102 face each other at a short distance, and both the base member 103 and the chamber 102 are formed of a conductive member. . For this reason, as described above, when a large current is passed through the CVD apparatus 100, the high-frequency current I ′ flows in the direction of the arrow in FIG. 4 and an abnormality occurs between the side surface 132 of the base member 103 and the inner wall surface 134 of the chamber 102. There is a risk of discharge. For this reason, impedance mismatching due to abnormal discharge occurs, and there is a problem that the upper limit value of power that can be supplied to the CVD apparatus 100 is lowered.

Therefore, the present invention has been made in view of the above-described circumstances, and suppresses the occurrence of abnormal discharge even when a large current flows through the apparatus when supplying high-frequency high power to the apparatus. Provided is a plasma processing apparatus capable of

In order to solve the above problems, a plasma processing apparatus according to a first aspect of the present invention includes an electrode flange, a chamber having an inner wall surface, an insulating flange disposed between the electrode flange and the chamber, and a side surface. A base member that is disposed in the chamber and on which the substrate is placed, an RF power source that is connected to the electrode flange and applies a high-frequency voltage, the side surface of the base member that faces the inner wall surface, and And an insulating member disposed on at least one of the inner wall surfaces facing the side surface of the base member.

According to this configuration, since at least one of the side surface of the base member and the inner wall surface of the chamber is covered with the insulating member, the conductive member is not disposed so as to face the exposed surface. Therefore, it is possible to suppress the occurrence of abnormal discharge between the side surface of the base member and the inner wall surface of the chamber. As a result, the upper limit value of the high frequency power that can be supplied to the apparatus can be increased.

In the plasma processing apparatus according to the first aspect of the present invention, it is preferable that the side surface of the base member facing the inner wall surface is electrically connected to the inner wall surface facing the side surface of the base member.

According to this configuration, when a high frequency high power is supplied to the electrode flange, a high frequency current can flow from the electrode flange to the chamber via the base member. Therefore, plasma can be generated between the electrode flange and the base member.

In the plasma processing apparatus according to the first aspect of the present invention, at least one position where the distance between the side surface of the base member facing the inner wall surface and the inner wall surface facing the side surface of the base member is the shortest. Preferably, the insulating member is provided.

According to this configuration, since the insulating member is provided at a position where the distance between the side surface of the base member and the inner wall surface of the chamber is the shortest distance, abnormal discharge is caused between the side surface of the base member and the inner wall surface of the chamber. It can suppress more reliably that it arises. As a result, the upper limit value of the high frequency power that can be supplied to the apparatus can be increased.

In the plasma processing apparatus according to the first aspect of the present invention, the chamber is preferably grounded.

According to this configuration, when a high frequency high power is supplied to the electrode flange, a high frequency current can flow from the electrode flange to the chamber via the base member. Further, since the potential of the chamber is maintained at the ground potential, plasma can be stably generated between the electrode flange and the base member.

According to the present invention, since at least one of the side surface of the base member and the inner wall surface of the chamber is covered with the insulating member, the conductive member is not disposed so as to face the exposed surface. Therefore, it is possible to suppress the occurrence of abnormal discharge between the side surface of the base member and the inner wall surface of the chamber. As a result, the upper limit value of the high frequency power that can be supplied to the apparatus can be increased.

It is a schematic sectional drawing which shows the structure of the plasma CVD apparatus in embodiment of this invention. It is a schematic sectional drawing which shows the structure of the plasma CVD apparatus in embodiment of this invention, Comprising: It is sectional drawing which expanded and showed the part shown by the code | symbol A in FIG. It is a figure explaining the route | root of the electric current which flows into the plasma CVD apparatus in embodiment of this invention. It is a schematic sectional drawing which shows the structure of the conventional plasma CVD apparatus, Comprising: It is sectional drawing which shows the part corresponding to FIG.

Hereinafter, embodiments of a plasma processing apparatus according to the present invention will be described with reference to the drawings.
In the drawings used for the following description, the dimensions and ratios of the respective components are appropriately changed from the actual ones in order to make the respective components large enough to be recognized on the drawings.
In this embodiment, a film forming apparatus using a plasma CVD method will be described.

FIG. 1 is a schematic cross-sectional view showing a configuration of a film forming apparatus in the present embodiment.
As shown in FIG. 1, a film forming apparatus 1 that performs a plasma CVD method includes a vacuum chamber 2 (chamber).
An opening is formed in the bottom 11 of the vacuum chamber 2. A support column 25 is inserted into the opening, and the support column 25 is disposed in the lower portion of the vacuum chamber 2. A plate-like base member 3 with a built-in heater 16 is connected to the tip of the column 25 (in the vacuum chamber 2). An electrode flange 4 is attached to the upper portion of the vacuum chamber 2 via an insulating flange 31. Further, an exhaust pipe 27 is connected to the vacuum chamber 2. A vacuum pump 28 is provided at the tip of the exhaust pipe 27. The vacuum pump 28 reduces the pressure so that the inside of the vacuum chamber 2 is in a vacuum state. Further, an outer frame 12 including an insulating flange 31 and an electrode flange 4 is provided above the vacuum chamber 2.

The support column 25 is connected to an elevating mechanism (not shown) provided outside the vacuum chamber 2 and can move up and down in the vertical direction of the substrate 10. In other words, the base member 3 connected to the tip of the support column 25 is configured to be able to move up and down. A bellows 26 is provided outside the vacuum chamber 2 so as to cover the outer periphery of the support column 25.

The electrode flange 4 is provided on the insulating flange 31 and is arranged so that the opening of the electrode flange 4 is located below in the vertical direction of the substrate 10. A shower plate 5 is attached to the opening of the electrode flange 4, that is, at a position where the electrode flange 4 faces the film formation space. A space 24 is formed between the shower plate 5 and the electrode flange 4.

A gas introduction pipe 7 is connected to the electrode flange 4. Outside the film forming apparatus 1, the gas introduction pipe 7 is connected to the film forming gas supply unit 21. A source gas (for example, SiH ₄ ) is supplied from the film forming gas supply unit 21 into the space 24 through the gas introduction pipe 7. The shower plate 5 is provided with a large number of gas ejection ports 6. The film forming gas introduced into the space 24 is ejected from the gas ejection port 6 into the vacuum chamber 2.

The electrode flange 4 and the shower plate 5 are made of a conductive material. The electrode flange 4 is connected to an RF power source (high frequency power source) 9 provided outside the vacuum chamber 2.

Furthermore, a gas introduction pipe 8 different from the gas introduction pipe 7 is connected to the vacuum chamber 2. The gas introduction pipe 8 is provided with a fluorine gas supply unit 22 and a radical source 23. The radical source 23 decomposes the fluorine gas supplied from the fluorine gas supply unit 22. The gas introduction pipe 8 supplies fluorine radicals obtained by decomposing fluorine gas to the film forming space in the vacuum chamber 2.

The base member 3 is a substantially plate-like member having a flat surface. A substrate 10 is placed on the upper surface of the base member 3. The base member 3 functions as a ground electrode and is made of, for example, an aluminum alloy. In addition, as a material of the base member 3, materials other than said material may be employ | adopted if it is a material which has rigidity and has corrosion resistance and heat resistance. If the board | substrate 10 is arrange | positioned on the base member 3, the board | substrate 10 and the shower plate 5 will adjoin and mutually become parallel. In a state where the substrate 10 is disposed on the base member 3, the film forming gas is supplied toward the surface of the substrate 10 through the gas ejection port 6. In the present embodiment, the distance between the substrate 10 and the shower plate 5 can be set to 3 mm to 10 mm, that is, a narrow gap can be realized.

A heater 16 is provided inside the base member 3. The temperature of the base member 3 is adjusted to a predetermined temperature by the heater 16. The power supply line 18 of the heater 16 protrudes from a substantially central portion of the base member 3 as viewed from the vertical direction of the base member 3 and the bottom surface 17 of the base member 3, is inserted into the support column 25, and is external to the vacuum chamber 2. Led to.
The power line 18 of the heater 16 is connected to a power source (not shown) outside the vacuum chamber 2 to adjust the temperature of the base member 3.

Further, a plurality of ground plates 30 (conductive members) that connect between the base member 3 and the vacuum chamber 2 are arranged at substantially equal intervals along the circumferential direction of the base member 3. The earth plate 30 is made of a flexible metal plate, and is made of, for example, a nickel-based alloy or an aluminum alloy. As the material of the earth plate 30, other materials may be adopted as long as they are made of a conductive material having a width of about 10 to 200 mm, have high corrosion resistance, and have flexibility.

FIG. 2 is a schematic cross-sectional view showing the configuration of the plasma CVD apparatus in the embodiment of the present invention, and is an enlarged cross-sectional view showing a portion indicated by reference numeral A in FIG.
As shown in FIG. 2, a locking portion 33 that locks the ground plate 30 is formed on the side surface (peripheral edge) 32 of the base member 3. The locking portion 33 is formed so as to protrude from the side surface 32 in the horizontal direction (the direction horizontal to the substrate 10). In the locking portion 33, the first end 30a of the ground plate 30 is locked and is electrically joined by a bolt (not shown) or the like.

Further, the second end 30b of the ground plate 30 is electrically joined to the inner wall surface 34 of the vacuum chamber 2 by a bolt (not shown) or the like. That is, the base member 3 and the vacuum chamber 2 are electrically connected by the ground plate 30. The plurality of ground plates 30 are arranged at substantially equal intervals along the periphery of the base member 3.

Specifically, the second end 30 b of the earth plate 30 is connected to the inner wall surface 34 of the vacuum chamber 2. The ground plate 30 extends downward from the connecting portion between the second end 30 b and the inner wall surface 34 along the inner wall surface 34. The earth plate 30 is folded back into a substantially U shape without extending to the bottom 11 of the vacuum chamber 2 and extends upward. That is, the ground plate 30 has a bent portion located between the first end 30a and the second end 30b. The ground plate 30 extending upward from the bent portion is folded back at a locking portion 33 formed on the side surface 32 of the base member 3. A first end 30 a of the ground plate 30 is connected to the base member 3.

Furthermore, in this embodiment, the insulating member 41 is disposed on the side surface 32 of the base member 3 so as to cover the side surface 32 and the first end 30a of the earth plate 30. An insulating member 42 is disposed on the inner wall surface 34 of the vacuum chamber 2 so as to cover the inner wall surface 34 and the second end 30 b of the earth plate 30. Note that the insulating member 41 and the insulating member 42 face each other.

Next, an operation when a film is formed on the substrate 10 using the film forming apparatus 1 having the above-described configuration will be described.
First, the vacuum chamber 2 is depressurized using the vacuum pump 28. The substrate 10 is carried into the vacuum chamber 2 and placed on the base member 3.
Here, before the substrate 10 is placed, the base member 3 is positioned below the vacuum chamber 2. That is, before the substrate 10 is carried in, the distance between the base member 3 and the shower plate 5 is wide, so that the substrate 10 can be easily placed on the base member 3 using a robot arm (not shown). can do.
After the substrate 10 is placed on the base member 3, an elevating device (not shown) is activated, the support column 25 is pushed upward, and the substrate 10 placed on the base member 3 also moves upward. To do. As a result, the interval between the shower plate 5 and the substrate 10 is determined as desired so that the interval necessary for proper film formation is achieved, and this interval is maintained. Here, the distance between the shower plate 5 and the substrate 10 is maintained at a distance suitable for forming a film on the substrate 10. At this time, the distance between the substrate 10 and the shower plate 5 is set to a narrow gap of 3 to 10 mm.
Thereafter, a film forming gas (raw material gas) is introduced into the space 24 through the gas introduction pipe 7, and the film forming gas is supplied into the vacuum chamber 2 through the gas outlet 6.

The electrode flange 4 is electrically insulated from the vacuum chamber 2 through an insulating flange 31. With the vacuum chamber 2 connected to the ground potential, the RF power source 9 is activated, and a high frequency voltage is applied to the electrode flange 4. As a result, a high frequency voltage is supplied between the shower plate 5 and the base member 3 to generate a discharge, and plasma is generated between the electrode flange 4 and the substrate 10. The film forming gas is decomposed in the plasma generated in this way, a plasma process gas is obtained, a vapor phase growth reaction occurs on the surface of the substrate 10, and a thin film is formed on the substrate 10.

Here, when a high frequency voltage is applied from the RF power source 9, a high frequency current I flows in the apparatus. As shown in FIG. 3, the high-frequency current I flows from the RF power source 9 to the surface of the electrode flange 4 and then flows to the surface of the shower plate 5. In addition, plasma is generated in the film formation space, and the high-frequency current I flows from the shower plate 5 to the base member 3 (substrate 10). The high-frequency current I that has reached the base member 3 flows on the surface of the base member 3 and flows in the ground plate 30. The high-frequency current I flowing from the first end 30 a to the second end 30 b of the ground plate 30 flows on the surface of the outer frame 12 after flowing on the surface of the vacuum chamber 2.

Thus, in the path of the high-frequency current I flowing through the film forming apparatus 1, a large current flows through the ground plate 30 connecting the side surface 32 of the base member 3 and the inner wall surface 34 of the vacuum chamber 2. As described above, since the insulating member 41 is disposed on the base member 3 side and the insulating member 42 is disposed on the vacuum chamber 2 side, the side surface 32 of the base member 3 and the inner wall surface 34 of the vacuum chamber 2 are arranged. Even if the gap is small, the occurrence of abnormal discharge can be suppressed.

Further, when the film forming process as described above is repeated several times, the film forming material adheres to the inner side surface 34 and the like of the vacuum chamber 2, so that the inside of the vacuum chamber 2 is periodically cleaned. In the cleaning process, the fluorine gas supplied from the fluorine gas supply unit 22 is decomposed by the radical source 23 to generate fluorine radicals. The fluorine radicals pass through the gas introduction pipe 8 connected to the vacuum chamber 2 and pass through the vacuum chamber 2. To be supplied. By supplying fluorine radicals to the film formation space 2 a in the vacuum chamber 2 in this way, a chemical reaction occurs, and the attachment attached to the members disposed around the vacuum chamber 2 or the inner side surface 34 of the vacuum chamber 2. The kimono is removed.

According to the present embodiment, since the side surface 32 of the base member 3 and the inner wall surface 34 of the vacuum chamber 2 are covered with the insulating

members

41 and 42, the conductive members are not arranged to face each other while being exposed. Therefore, when supplying high frequency high power to the apparatus, even if a large current flows through the apparatus, abnormal discharge occurs between the side surface 32 of the base member 3 and the inner wall surface 34 of the vacuum chamber 2. Can be suppressed. As a result, the upper limit value of the high frequency power that can be supplied to the film forming apparatus 1 can be increased.

Next, the maximum power that can be supplied to the film forming apparatus 1 when forming a film using the film forming apparatus 1 described above will be described.
The power frequency applied to the film forming apparatus 1 from the RF power source 9 was set to 27.12 MHz. The size of the shower plate 5 (size viewed from the vertical direction of the substrate 10) is set to 1300 mm × 1600 mm, and the size of the base member 3 (size viewed from the vertical direction of the substrate 10) is set to 1400 mm × 1700 mm. The size of the substrate 10 was set to 1100 mm × 1400 mm. The ratio of the flow rate of SiH ₄ that is the deposition gas and the flow rate of H ₂ was set to 1:25, and μc-Si was deposited on the substrate 10.
Further, as a variable parameter, the distance (ES) between the shower plate 5 and the substrate 10 was changed every 4 mm between 4 mm and 10 mm. Further, the maximum power that can be supplied to the film forming apparatus 1 when the pressure in the film forming space was set to 700 Pa, 1300 Pa, and 2000 Pa was measured.

Table 1 shows the measurement results.
“Unmeasured” indicates a result when the insulating

members

41 and 42 are not arranged as in the conventional film forming apparatus. “Countermeasured” indicates the result when the insulating

members

41 and 42 are arranged as in the film forming apparatus 1 of the present embodiment.
Even when the distance between the shower plate 5 and the substrate 10 is changed and when the pressure in the film formation space is changed, the measurement result of “measured” is higher than the measurement result of “unmeasured”. I understand that. That is, the maximum power value that can be supplied to the “measured” film forming apparatus 1 can be increased.

Therefore, by providing the insulating

members

41 and 42 on the side surface 32 of the base member 3 and the inner wall surface 34 of the vacuum chamber 2 as in the present embodiment, a large current is supplied to the device when supplying high-frequency high power to the device. Even if it flows, it is possible to suppress the occurrence of abnormal discharge between the side surface 32 of the base member 3 and the inner wall surface 34 of the vacuum chamber 2. Therefore, the maximum power value that can be supplied to the film forming apparatus 1 can be increased.
As a result, when the μc-Si film is formed with a narrow gap between the substrate 10 and the shower plate 5, the film formation rate can be increased, and high-quality μc-Si film can be formed.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. That is, the specific materials or configurations described in the present embodiment are examples of the present invention, and can be appropriately changed.

For example, in the present embodiment, the configuration in which the insulating member is disposed on both the side surface of the base member and the inner wall surface of the vacuum chamber has been described, but it is only necessary that the insulating member is disposed on at least one of them.
In the present embodiment, the configuration in which the insulating member is disposed on the side surface of the base member and the inner wall surface of the vacuum chamber has been described. However, the surface of the earth plate may be covered with the insulating member.

As described above in detail, the present invention is useful for a plasma processing apparatus capable of suppressing the occurrence of abnormal discharge even when a large current flows through the apparatus when supplying high-frequency high power to the apparatus. is there.

DESCRIPTION OF SYMBOLS 1 ... Film-forming apparatus (plasma processing apparatus) 2 ... Vacuum chamber (chamber) 3 ... Base member 4 ... Electrode flange 10 ... Substrate 31 ... Insulating flange 32 ... Side surface of base member 34 ... Inner wall surface of vacuum chamber 41 ... Insulating member 42 ... insulating members.

Claims

A plasma processing apparatus,
An electrode flange;
A chamber having an inner wall surface;
An insulating flange disposed between the electrode flange and the chamber;
A base member having a side surface, disposed in the chamber, on which a substrate is placed;
An RF power source connected to the electrode flange and applying a high frequency voltage;
An insulating member disposed on at least one of the side surface of the base member facing the inner wall surface and the inner wall surface facing the side surface of the base member;
A plasma processing apparatus comprising:
The plasma processing apparatus according to claim 1,
The plasma processing apparatus, wherein a side surface of the base member facing the inner wall surface is electrically connected to the inner wall surface facing the side surface of the base member.
The plasma processing apparatus according to claim 1 or 2,
The insulating member is provided at at least one position where the distance between the side surface of the base member facing the inner wall surface and the inner wall surface facing the side surface of the base member is the shortest. A plasma processing apparatus.
The plasma processing apparatus according to any one of claims 1 to 3, wherein
The plasma processing apparatus, wherein the chamber is grounded.