WO2014203719A1

WO2014203719A1 - Plasma processing apparatus and plasma processing method

Info

Publication number: WO2014203719A1
Application number: PCT/JP2014/064681
Authority: WO
Inventors: 仁彦出道; 範芳小浜; 朋宏福田
Original assignee: 東京エレクトロン株式会社; シャープ株式会社
Priority date: 2013-06-21
Filing date: 2014-06-03
Publication date: 2014-12-24
Also published as: JP2015005634A

Abstract

In a plasma film-forming apparatus (100), a supplementary plate (9) as a protruding section is mounted on substantially the whole non-placing region (R2) of a lower electrode (5). The supplementary plate (9) has a frame shape, and is disposed to surround the whole rectangular placing region (R1). The supplementary plate (9) is a board-like member that can be attached to and detached from the lower electrode (5), and is configured from a dielectric material, such as quartz, ceramic, and heat-resistant synthetic resin, or a conductive material, such as aluminum, aluminum alloy, and stainless steel. A step (80) between a substrate (S) and the lower electrode (5) is reduced or eliminated by means of the supplementary plate (9), and a gas (G) is made to easily flow to a corner section of the substrate (S).

Description

Plasma processing apparatus and plasma processing method

The present invention relates to a plasma processing apparatus and a plasma processing method for performing plasma processing on an object to be processed.

In a manufacturing process of a semiconductor substrate, a flat panel display (FPD) typified by a liquid crystal display (LCD), a solar cell, or the like, a predetermined process such as etching or film formation is performed on the substrate. As a plasma processing apparatus used for such processing, a parallel plate type plasma processing apparatus is known.

In a plasma etching apparatus that performs a plasma etching process on a substrate, a focus ring is disposed around the substrate in order to control the state of plasma near the outer periphery of the substrate. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2005-136350) proposes that a quartz focus ring is disposed around a substrate in a plasma etching apparatus that performs plasma etching on an FPD substrate. In Patent Document 2 (Japanese Patent Laid-Open No. 2002-110652), there is a proposal for adjusting the impedance of a focus ring in a plasma etching apparatus that performs a plasma etching process on a semiconductor substrate. Further, Patent Document 3 (Japanese Patent Laid-Open No. 2006-173223) discloses that, in a plasma etching apparatus that performs a plasma etching process on a semiconductor substrate, the etching rate depends on the height of the focus ring.

When plasma processing is performed on a large substrate having a large area using a parallel plate type plasma processing apparatus, it is important to ensure uniformity of processing within the surface of the substrate. However, for example, the solar cell substrate is rectangular, so unlike the circular semiconductor substrate, the deposition rate at the corners of the substrate tends to be lower than the central portion, or in the film formation of microcrystalline silicon, There has been a problem that the degree of crystallinity tends to be uneven. In addition, since the solar cell substrate has a thickness several times that of the LCD substrate used for manufacturing the liquid crystal display, a step is generated between the substrate and the mounting table. Due to this step, the gas supply to the corner portion becomes insufficient, or the spread of plasma is suppressed, and the deposition rate of the corner portion of the substrate is further reduced compared to the central portion, In the formation of microcrystalline silicon, there is a problem that the degree of crystallinity decreases. In particular, since the solar cell plasma processing apparatus used for producing microcrystalline silicon is used at a relatively high pressure of 400 Pa or more, there is a problem that the flow of gas becomes slow and the influence is larger.

The present invention provides a plasma processing apparatus capable of ensuring the uniformity of processing within the substrate surface.

The plasma processing apparatus of the present invention provides a high-frequency power to at least one of a processing container that can be evacuated, an upper electrode and a lower electrode that are disposed to face each other, and the upper electrode or the lower electrode. And a high-frequency power supply to be supplied. In the plasma processing apparatus of the present invention, the lower electrode is provided adjacent to the rectangular mounting area for mounting the rectangular substrate and the outer side so as to surround the mounting area, and the substrate is not mounted. And a non-mounting area. And the plasma processing apparatus of this invention has provided the convex part in the one part or the whole of the said non-mounting area | region.

In the plasma processing apparatus of the present invention, the convex portion may be partially provided around a corner of the rectangular mounting region.

In the plasma processing apparatus of the present invention, the upper electrode or the lower electrode may have a rectangular shape in plan view, and in the upper electrode or the lower electrode, a feeding portion to which high-frequency power is supplied from the high-frequency power source, You may be provided in the side part which makes the long side of the said rectangle. In this case, the convex portion may be partially provided outside the long side of the rectangular mounting region on the same side as the power feeding site, or the rectangle on the side opposite to the power feeding site. It may be partially provided outside the long side of the mounting area.

In the plasma processing apparatus of the present invention, the convex portion may be provided so as to surround the entire rectangular mounting region.

In the plasma processing apparatus of the present invention, the height of the convex portion may be the same as the thickness of the substrate placed in the placement area, or may be smaller than the thickness of the substrate. Good.

In the plasma processing apparatus of the present invention, the height of the convex portion is relatively high around the corner of the rectangular placement region, and the short side or the central portion of the long side of the rectangular placement region. It may be formed low in a portion adjacent to the.

In the plasma processing apparatus of the present invention, the convex portion may be provided integrally with the lower electrode.

In the plasma processing apparatus of the present invention, the convex portion may be a plate-like member that can be attached to and detached from the lower electrode.

In the plasma processing apparatus of the present invention, the convex portion may be made of a dielectric or a conductor.

In the plasma processing apparatus of the present invention, the substrate may be a glass substrate for solar cells.

In the plasma processing method of the present invention, in any one of the above plasma processing apparatuses, the substrate is placed in the mounting area and plasma processing is performed. In this case, a film forming process by a plasma CVD method may be performed on the substrate.

According to the plasma processing apparatus and the plasma processing method of the present invention, in the lower electrode, since the convex portion is provided in a part or the whole of the non-mounting region where the substrate is not mounted, even when processing a rectangular substrate, In particular, a decrease in the deposition rate and crystallinity of the corner portion is improved, and the uniformity of processing within the substrate surface can be ensured.

It is sectional drawing which shows the schematic structural example of the plasma film-forming apparatus which concerns on the 1st Embodiment of this invention. It is a top view of the state which mounted the board | substrate in the lower electrode in the plasma film-forming apparatus of FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. It is a schematic diagram explaining the flow of the gas on the board | substrate in the conventional plasma film-forming apparatus. It is a schematic diagram explaining the flow of the gas on the board | substrate in the conventional plasma film-forming apparatus. It is a schematic diagram explaining the flow of the gas on the board | substrate in the plasma film-forming apparatus which concerns on 1st Embodiment. It is a schematic diagram explaining the flow of the gas on the board | substrate in the plasma film-forming apparatus which concerns on 1st Embodiment. It is drawing used for description of the height of the auxiliary | assistant plate in the plasma film-forming apparatus which concerns on 1st Embodiment. It is drawing used for description of the height of the auxiliary | assistant plate in the plasma film-forming apparatus which concerns on 1st Embodiment. In the plasma film-forming apparatus which concerns on the 2nd Embodiment of this invention, it is a top view of the state which mounted the board | substrate in the lower electrode. It is a principal part perspective view which shows the state which installed the auxiliary | assistant plate in the lower electrode in the plasma film-forming apparatus which concerns on the 2nd Embodiment of this invention. In the plasma film-forming apparatus which concerns on the 3rd Embodiment of this invention, it is a top view of the state which mounted the board | substrate in the lower electrode. It is sectional drawing of the lower electrode in the plasma film-forming apparatus which concerns on the 4th Embodiment of this invention. It is drawing explaining the arrangement | positioning of the measurement point and auxiliary | assistant plate on a board | substrate in an experiment example. 10 is a graph showing the result of the deposition rate in Experimental Example 1. 6 is a graph showing the results of crystallinity in Experimental Example 1. It is a graph which shows the result of the deposition rate in example 2 of an experiment. 6 is a graph showing the results of crystallinity in Experimental Example 2.

Hereinafter, a plasma film forming apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
A plasma film forming apparatus according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view showing a schematic configuration example of a plasma film forming apparatus 100 according to the first embodiment of the present invention. 2 is a plan view of a state in which the substrate S as the object to be processed is placed on the lower electrode 5 in the plasma film forming apparatus 100, and FIG. 3 is a cross-sectional view taken along the line III-III in FIG. It is.

As shown in FIG. 1, a plasma film forming apparatus 100 includes a processing container 1 capable of evacuating a rectangular substrate S, and an upper electrode 3 as a cathode electrode disposed opposite to each other in the processing container 1. And a lower electrode 5 as an anode electrode. The plasma film forming apparatus 100 includes a high frequency power source 7 that supplies high frequency power to the upper electrode 3, an auxiliary plate 9 that is a plate-like member provided on the lower electrode 5, and the plasma film forming apparatus 100. And a control unit 60 for controlling the respective components. The plasma film forming apparatus 100 is configured as a batch type parallel plate type plasma film forming apparatus that performs film formation on a plurality of substrates S simultaneously by, for example, a plasma CVD method. In addition, as the board | substrate S, the glass substrate for solar cells can be mentioned.

<Processing container>
The processing container 1 has a box shape that can be evacuated. The processing container 1 is grounded. For example, a metal such as aluminum, an aluminum alloy, or stainless steel is used for the processing container 1. The processing container 1 includes a ceiling portion 11, a rectangular tubular side wall portion 13, and a bottom wall portion 15. The side wall 13 is provided with an opening (not shown) that is opened and closed when the substrate S is loaded and unloaded, and the opening is opened and closed by a gate valve. Further, an exhaust port 15 a is formed in the bottom wall portion 15. The exhaust port 15 a is connected to the exhaust device 21 via the exhaust pipe 23.

<Parallel plate electrode>
The upper electrode 3 and the lower electrode 5 are arranged in parallel to each other and form a pair of parallel plate electrodes. Both the upper electrode 3 and the lower electrode 5 are made of a metal such as aluminum, aluminum alloy, stainless steel, or the like. Both the upper electrode 3 and the lower electrode 5 are rectangular in plan view.

The upper electrode 3 has a function as a shower head for introducing gas into the processing container 1. That is, the upper electrode 3 has a hollow shape, and a gas diffusion space 31 is provided therein. A plurality of gas discharge holes 33 for discharging a processing gas are formed on the lower surface of the upper electrode 3. Further, a gas introduction portion 35 communicating with the gas diffusion space 31 is provided on the side portion of the upper electrode 3. Further, the lower surface of the upper electrode 3 forms a facing surface 37 facing the lower electrode 5. The upper electrode 3 may not have a function as a shower head. For example, the upper electrode 3 may be a flat metal plate that does not include the gas diffusion space 31 and the gas discharge hole 33. A power supply unit (not shown) to which high-frequency power from the high-frequency power source 7 is supplied is provided on the long side of the upper electrode 3.

As shown in FIG. 2, the lower electrode 5 has a rectangular shape as a whole, and has a long side 5a and a short side 5b. The lower electrode 5 is fixed to the side wall portion 13 of the processing container 1. Therefore, the lower electrode 5 is at ground potential. The upper surface of the lower electrode 5, that is, the surface facing the upper electrode 3 is a substrate mounting surface on which the substrate S is mounted. The substrate placement surface of the lower electrode 5 has a rectangular placement region R1 on which the rectangular substrate S is placed and a non-placement region R2 on which the substrate S is not placed. The non-mounting region R2 is provided adjacent to the outside so as to surround the mounting region R1. Further, the lower electrode 5 has a plurality of substrate support pins (not shown) that can project and retract with respect to the substrate mounting surface, and use the substrate support pins to communicate with an external transfer device. The delivery of the substrate S can be performed. In FIG. 2, of the non-mounting region R2, the periphery of the corner of the rectangular mounting region R1 is represented by reference numerals C1, C2, C3, and C4, and the short side or the long side of the rectangular mounting region R1 is shown. The periphery of the central portion is represented by reference numerals E1, E2, E3, and E4.

<Convex part>
In plasma deposition apparatus 100 of the present embodiment, auxiliary plate 9 as a convex portion is attached to almost the entire non-mounting region R2 of lower electrode 5. In the present embodiment, the auxiliary plate 9 has a frame shape and is disposed so as to surround the entire rectangular placement region R1. The auxiliary plate 9 is a plate-like member that can be attached to and detached from the lower electrode 5. In addition, the auxiliary | assistant plate 9 may be divided | segmented into the some part and does not need to be frame shape.

The auxiliary plate 9 is made of a dielectric or a conductor. Examples of the dielectric include quartz, ceramics, and heat-resistant synthetic resin. Examples of the conductor include the same material as the lower electrode 5, for example, a metal material such as aluminum, an aluminum alloy, and stainless steel.

<Plasma processing section>
In the plasma film forming apparatus 100 of the present embodiment, one upper electrode 3 and one lower electrode 5 form a pair to constitute one plasma processing unit 10. In the processing container 1, a plurality of plasma processing units 10 are stacked in multiple stages. As a result, the plasma film forming apparatus 100 can batch process a plurality of substrates S at the same time. The number of plasma processing units 10 in the processing container 1 can be set in the range of 3 to 10, for example.

<High frequency power supply>
The upper electrode 3 is provided with a power supply unit (not shown), and a power supply line 71 is connected to the power supply unit. The power supply line 71 is connected to a high-frequency power source 7 for plasma formation via a matching unit 73. Thereby, for example, high frequency power of 11 MHz is supplied from the high frequency power supply 7 to each upper electrode 3. The power supply line 71 is introduced into the processing container 1 through a power supply opening 13 a formed in the side wall portion 13 of the processing container 1. A vacuum holding means such as a bellows (not shown) is provided around the power supply opening 13a.

The matching unit 73 is provided with a matching circuit (not shown) having one end connected to the high frequency power supply 7 via a coaxial cable, for example, and the other end of the matching circuit is connected to the upper electrode via the feeder 71. 3 is connected to the side of the long side. The matching circuit performs impedance adjustment (matching) between the load (plasma) and the high-frequency power source 7 in accordance with the impedance of the plasma, and plays a role of attenuating the reflected wave generated in the circuit of the plasma film forming apparatus 100.

<Exhaust mechanism>
The plasma film forming apparatus 100 further includes an exhaust mechanism 20 that exhausts the inside of the processing container 1 under reduced pressure. The exhaust mechanism 20 includes, for example, an exhaust device 21 having a vacuum pump such as a dry pump, and an exhaust pipe 23 connecting the exhaust device 21 and the exhaust port 15a. By operating the vacuum pump of the exhaust device 21, the internal space of the processing container 1 is evacuated to a predetermined degree of vacuum.

<Gas supply device>
The plasma film forming apparatus 100 further includes a gas supply device 40 that supplies a gas into the processing container 1. The gas supply device 40 is connected to the gas supply source 41, a plurality of pipes 43 (only one is shown) for introducing a processing gas into the processing container 1, and a plurality of pipes 43 provided to these pipes 43. Valve 45 (only two are shown) and a mass flow controller (MFC) 47. The plurality of pipes 43 are connected to a gas introduction part 35 provided on a side part of the upper electrode 3 via a gas introduction part 13 b of the side wall part 13 of the processing container 1. Accordingly, the processing gas can be supplied from the gas supply source 41 to the gas diffusion space 31 via the pipe 43, the gas introduction part 13 b, and the gas introduction part 35. The type of gas supplied to the gas diffusion space 31 and the flow rate of these gases are controlled by opening and closing the mass flow controller 47 and the valve 45. Instead of the gas supply device 40, an external gas supply device not included in the configuration of the plasma film forming apparatus 100 may be used.

<Control unit>
Each component of the plasma film forming apparatus 100 is connected to the control unit 60 and controlled by the control unit 60. The control unit 60 is typically a computer. The control unit 60 includes a controller 61 having a CPU, and a user interface 62 and a storage unit 63 connected to the controller 61.

In the plasma film forming apparatus 100, the controller 61 is a component related to process conditions such as high-frequency output, impedance matching by the matching unit 73, pressure in the processing chamber 1, gas flow rate, etc. (for example, the high-frequency power source 7, matching unit). 73, the exhaust device 21, the gas supply device 40, etc.).

The user interface 62 includes a keyboard and a touch panel on which a process manager manages command input to manage the plasma film forming apparatus 100, a display that visualizes and displays the operating status of the plasma film forming apparatus 100, and the like. Yes.

The storage unit 63 stores a control program (software) for realizing various processes executed by the plasma film forming apparatus 100 under the control of the controller 61, a recipe in which process condition data, and the like are recorded. . The controller 61 calls and executes an arbitrary control program or recipe from the storage unit 63 as necessary, such as an instruction from the user interface 62. Accordingly, a desired process is performed in the processing container 1 of the plasma film forming apparatus 100 under the control of the controller 61.

The control program and recipe described above can be stored in a computer-readable storage medium such as a CD-ROM, hard disk, flexible disk, flash memory, or DVD. Also, the above recipe can be transmitted from other devices as needed via, for example, a dedicated line and used online.

Here, the operation of the plasma film forming apparatus 100 of the present embodiment will be described with reference to FIGS. 4 and 5 are schematic diagrams for explaining the flow of gas on the substrate S in the conventional plasma film forming apparatus. FIG. 4 shows a cross section near the corner of the substrate S. The substrate S for solar cells has a thickness T of about 2 mm to 4 mm, for example, several times to about 10 times the thickness of a glass substrate for FPD having a thickness of about 0.3 mm to 0.7 mm. Yes. Therefore, for example, as shown in FIG. 4, a step 80 is generated between the end portion of the substrate S and the upper surface of the lower electrode 5, and the distance between the upper electrode 3 and the lower electrode 5 changes substantially.

This step 80 makes the flow of the gas G from the surface of the substrate S toward the peripheral edge of the substrate S non-uniform. That is, as shown in FIG. 5, the flow of the gas G tends to go in the direction of the step 80 having a lower flow path resistance, so that the flow from the vicinity of the center of the substrate S toward the step 80 at the shortest distance increases. The flow to the corner portion of the substrate S becomes small. In FIG. 5, the thickness of the white arrow indicates the flow rate of the gas G, and the thicker the flow rate, the greater the flow rate (the same applies in FIG. 7). The corner portion of the substrate S is originally an area where the gas G is difficult to reach because the distance from the center of the substrate S is the longest, but the corner portion of the substrate S is formed by the step 80 between the substrate S and the upper surface of the lower electrode 5. The flow of gas G to the gas further decreases. As a result, the deposition rate is reduced, and in the film formation of microcrystalline silicon, the film is formed in a pressure region of 400 Pa or more, so that the gas flow becomes slow and the crystallization of the microcrystalline silicon proceeds. The tendency to decrease becomes stronger.

Further, the step 80 caused by the thickness of the substrate S suppresses the spread of the plasma P formed between the parallel plate electrodes in the lateral direction. That is, at the peripheral portion of the substrate S, the distance (gap) from the substrate S or the lower electrode 5 to the upper electrode 3 varies greatly due to the presence of the step 80, so that the impedance between the parallel plate electrodes changes, and the plasma density increases. descend. As a result, as shown in FIG. 4, the plasma P does not spread to the peripheral portion of the substrate S, particularly to the corner portion where the distance from the center of the substrate S is the largest. As a result, the deposition rate is reduced, and in the formation of microcrystalline silicon, the film is formed in a pressure region of 400 Pa or higher, so that the plasma P is less likely to spread and the progress of crystallization of microcrystalline silicon is reduced. The tendency becomes stronger.

The decrease in the deposition rate and the decrease in the degree of crystallinity of microcrystalline Si due to the step 80 as described above are problems that have hardly occurred when a circular semiconductor substrate or an FPD substrate having a small thickness is used as an object to be processed. is there.

6 and 7 are schematic diagrams for explaining the gas flow on the substrate S in the plasma film forming apparatus 100 of the present embodiment in which the auxiliary plate 9 as a convex portion is provided in the non-mounting region R2. FIG. 6 is a cross-sectional view of the lower electrode 5 of the present embodiment in which an auxiliary plate 9 as a convex portion is provided in the non-mounting region R2. FIG. 6 shows a cross section taken along line VI-VI in FIG. The step 80 between the substrate S and the lower electrode 5 can be reduced or eliminated by the auxiliary plate 9. By reducing or eliminating the step 80, the flow of the gas G is easily directed toward the corner of the substrate S as shown in FIG. In FIG. 7, the thickness of the white arrow indicates the flow rate of the gas G. Further, the auxiliary plate 9 promotes the spread of the plasma P between the parallel plate electrodes by reducing or eliminating the step 80, and the plasma P is also provided above the corner portion of the substrate S as shown in FIG. Has the effect of encouraging the spread.

As described above, it is considered that the height of the action of the auxiliary plate 9 of the present embodiment is more important than the material of the auxiliary plate 9. For this reason, the action of the auxiliary plate 9 of the present embodiment is considered to have a different mechanism of action from the focus ring used in the conventional plasma etching apparatus. In addition, the plasma film forming apparatus 100 of the present embodiment is suitable for processing a large substrate S having a short side exceeding 1 m, for example, and in particular a solar cell substrate having a thickness T in the range of 2 mm to 4 mm. Suitable for processing.

Next, the relationship between the thickness of the substrate S and the height of the auxiliary plate 9 will be described with reference to FIGS. 8 and 9 are cross-sectional views of the main part near the surface of the lower electrode 5 for explaining the height of the auxiliary plate in the plasma film forming apparatus.

In FIG. 6, the height H1 of the auxiliary plate 9 is substantially the same as the thickness T of the substrate S placed in the placement region R1 (that is, H1 = T). In this case, the film-forming gas G injected from the gas discharge hole 33 of the upper electrode 3 having a function as a shower head toward the upper surface of the substrate S is as shown by the white arrow in FIG. It can flow smoothly from the central part side toward the peripheral part. Further, by eliminating the step 80, the plasma P also expands in the lateral direction and reaches the peripheral edge of the substrate S sufficiently. As described above, the auxiliary plate 9 has an action of urging the deposition gas G and the plasma P to reach the peripheral portion of the substrate S, particularly the corner portion. However, the height of the auxiliary plate 9 can be set smaller than or larger than the thickness of the substrate S.

In the example shown in FIG. 8, the height H2 of the auxiliary plate 9 is set smaller than the thickness T of the substrate S placed in the placement region R1 (that is, H2 <T). In this case, the step 80 is not completely eliminated, but the step is reduced by the height H2 of the auxiliary plate 9. As a result, the flow of the gas G that escapes toward the long side or short side step 80 of the substrate S at the shortest distance without going from the vicinity of the center of the substrate S to the corner portion is greater than in the case of FIGS. Get smaller. Further, the spread of the plasma P in the lateral direction at the corner of the substrate S is also larger than in the case of FIG. Here, from the viewpoint of appropriately controlling the flow of the gas G and the spread of the plasma P, the height H2 is preferably set within a range of 0.5T ≦ H2 <T, for example.

In the example shown in FIG. 9, the height H3 of the auxiliary plate 9 is set to be larger than the thickness T of the substrate S placed on the placement region R1 (that is, H3> T). In this case, a step 81 opposite to that in FIG. 4 occurs, but the auxiliary plate 9 serves as a weir, so that the gas G stays on the substrate S, and as a result, the gas G reaches the peripheral edge of the substrate S. Conceivable. On the other hand, it is considered that the spread of the plasma P in the lateral direction at the corner portion of the substrate S is slightly suppressed by the step 81 between the substrate S and the auxiliary plate 9. Here, from the viewpoint of appropriately controlling the flow of the gas G and the spread of the plasma P, the height H3 is preferably set within a range of T <H3 ≦ 2T, for example.

As described above, the flow of the gas G on the substrate S and the spread of the plasma P can be finely adjusted by changing the height of the auxiliary plate 9. For example, in the non-mounting region R2, the height of the auxiliary plate 9 is set to be relatively high around the corners C1, C2, C3, and C4 of the rectangular mounting region R1, and the non-mounting region R2 Further, it can be set low in the periphery E1, E2, E3, and E4 around the central part of the short side or the long side of the rectangular placement region R1. Specifically, the height of the auxiliary plate 9 is set to the above H1 at the corners C1, C2, C3, and C4 around the corner of the placement region R1 (see FIG. 6; where H1 = T), In the surroundings E1, E2, E3, and E4 around the short side or the long side of the placement region R1, the above H2 is set (see FIG. 8; here, H2 <T). In this way, by changing the height according to the portion of the auxiliary plate 9, the flow of the gas G and the spread of the plasma P on the substrate S are made uniform, and the film forming process in the plane of the substrate S is performed. Uniformity can be achieved.

[Processing procedure]
Next, a processing procedure when performing the film forming process by the plasma CVD method on the substrate S by the plasma film forming apparatus 100 will be described. First, for example, a command is input from the user interface 62 to the controller 61 so as to perform a film forming process in the plasma film forming apparatus 100. Next, in response to this command, the controller 61 reads a recipe stored in the storage unit 63 or a computer-readable storage medium. Next, each end device of the plasma film forming apparatus 100 (for example, the high frequency power supply 7, the matching unit 73, the exhaust device 21, the gas supply device 40, etc.) is executed from the controller 61 so that the film forming process is executed according to the conditions based on the recipe. ) Is sent a control signal.

Next, the gate valve (not shown) is opened, and a plurality of substrates S are carried into the processing container 1 through the gate valve and the opening (not shown) of the side wall 13 by an external transfer device. The Each substrate S is placed on the lower electrode 5 via a plurality of substrate support pins (not shown). Next, the gate valve is closed, and the inside of the processing container 1 is evacuated by the exhaust device 21. Next, a processing gas having a predetermined flow rate is injected from the gas discharge hole 33 of the upper electrode 3 toward the upper surface of the substrate S by the gas supply device 40. The internal space of the processing container 1 is adjusted to a predetermined pressure by adjusting the exhaust amount and the gas supply amount.

Next, by supplying high frequency power from the high frequency power supply 7 to each upper electrode 3, plasma of a processing gas is generated between the upper electrode 3 and the lower electrode 5 forming parallel plate electrodes in each plasma processing unit 10. Is done. A predetermined thin film is deposited on the surface of the substrate S by the generated plasma. During this plasma processing, the flow of the gas G on the surface of the substrate S and the spread of the plasma P are appropriately adjusted by the auxiliary plate 9, so that the in-plane film forming processing on the substrate S is made uniform. Can be planned.

When a control signal for terminating the film forming process is sent from the controller 61 to each end device of the plasma film forming apparatus 100, the supply of the high frequency from the high frequency power supply 7 is stopped and the supply of the processing gas is stopped. The film forming process for the substrate S is completed. Next, after the gate valve is opened and the height position of each substrate S is adjusted by the substrate support pins, the plurality of substrates S are unloaded from the processing container 1 by an external transfer device.

As described above, in the present embodiment, by arranging the auxiliary plate 9 on the lower electrode 5, the uniformity of the film forming process within the surface of the substrate S can be improved. Therefore, the plasma film forming apparatus 100 can be preferably used for the purpose of performing a film forming process on the substrate S, for example, in a solar cell manufacturing process.

[Second Embodiment]
Next, a plasma film forming apparatus according to a second embodiment of the present invention will be described with reference to FIGS. 10 and 11 are explanatory views showing the arrangement of the auxiliary plate 91 on the lower electrode 5 in the second embodiment. Here, differences from the first embodiment will be described.

<Convex part>
In the present embodiment, the auxiliary plate 91 as a plate-like member constituting the convex portion is partially arranged around the corner of the rectangular placement region R1. That is, in the non-mounting region R2 of the lower electrode 5, the auxiliary plate 91 is disposed only around the corners C1, C2, C3, and C4 of the rectangular mounting region R1. As described above, the corner portion of the substrate S is the portion where the gas G hardly reaches in the plane of the substrate S. Therefore, in the present embodiment, the auxiliary plate 91 is disposed only around the corners of the rectangular placement region R1 in the non-mounting region R2, so that the corner portion of the substrate S is disposed. It is possible to improve film formation defects such as a decrease in the deposition rate of the film and to achieve uniform film formation processing within the surface of the substrate S.

In the present embodiment, the auxiliary plate 91 includes a rectangular partial auxiliary plate 91A and a rectangular partial auxiliary plate 91B. That is, the auxiliary plate 91 includes a combination of two partial

auxiliary plates

91A and 91B. The partial auxiliary plates 91 A and 91 B are plate-like members that can be attached to and detached from the lower electrode 5. In addition, each auxiliary plate 91 may be integrally formed, for example with the planar view L-shaped member, or may be comprised by the 3 or more partial plate.

Other configurations and effects of the plasma film forming apparatus of the present embodiment are the same as those of the plasma film forming apparatus 100 of the first embodiment, and thus description thereof is omitted. The auxiliary plate 91 need not be provided at all four locations C1, C2, C3, and C4 around the corner of the placement region R1 in the non-mounting region R2, but can be provided at any location.

[Third Embodiment]
Next, a plasma film forming apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 12 is an explanatory diagram showing the arrangement of convex portions on the lower electrode 5 in the third embodiment. Here, differences from the first embodiment will be described.

<Convex part>
In the present embodiment, the auxiliary plate 93 as a plate-like member constituting the convex portion is partially arranged outside the central portion of the long side of the rectangular placement region R1. High frequency power is supplied to the upper electrode 3 from a high frequency power source 7. In FIG. 12, the position of the lower electrode 5 corresponding to the power supply portion to which the power supply line 71 is connected in the upper electrode 3 is indicated by an arrow P 1 (hereinafter referred to as a power supply position P 1). The feeding position P 1 is provided on the side of the upper electrode 3 that forms the long side of the rectangle. In the present embodiment, the auxiliary plate 93 serving as a plate-like member constituting the convex portion takes into consideration the power feeding position P1 in the upper electrode 3, and the non-mounting region R2 near the center of the long side 5a of the lower electrode 5. Is placed only in. That is, in the non-mounting region R2, the auxiliary plate 93 is located in the periphery E3 of the central portion of the long side of the mounting region R1 on the same side as the power feeding position P1 and the mounting region R1 on the opposite side to the power feeding position P1. It is provided in the periphery E4 of the center part of a long side, respectively.

As shown in FIG. 12, when the feeding position P1 in the upper electrode 3 is provided opposite to the center of the long side 5a of the lower electrode 5, the electric field distribution between the parallel plate electrodes is biased, and feeding is performed. The deposition rate decreases in the region close to the position P1 or the region on the opposite side of the power feeding position P1 (that is, near the center of the long side of the peripheral portion of the substrate S), and in the case of a microcrystalline silicon film, the crystallinity is low. May be lower. Therefore, in the plasma film forming apparatus of the present embodiment, the outside of the central portion of the long side of the mounting region R1 on the same side as the power feeding position P1 and the long side of the mounting region R1 on the side opposite to the power feeding position P1. Auxiliary plates 93 were provided on the outside of the central part. The auxiliary plate 93 can locally increase the gas flow in the vicinity of the center of the long side of the peripheral portion of the substrate S more than other parts, or can promote the expansion of the plasma P locally. Therefore, it is possible to improve film formation defects such as a decrease in the deposition rate and make the film formation process uniform in the plane of the substrate S.

The auxiliary plate 93 has a periphery E3 around the central portion of the long side of the mounting region R1 on the same side as the power feeding position P1, or a periphery of the central portion of the long side of the mounting region R1 on the side opposite to the power feeding position P1. You may provide in either one of E4.

Other configurations and effects of the plasma film forming apparatus of the present embodiment are the same as those of the plasma film forming apparatus 100 of the first embodiment, and thus description thereof is omitted.

[Fourth Embodiment]
Next, a plasma film forming apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 13 is a cross-sectional view of the lower electrode 5 in the fourth embodiment. Here, differences from the first embodiment will be described.

In the present embodiment, the convex portion 95 is provided integrally with the lower electrode 5. In this case, the convex portion 95 can be formed by performing processing such as cutting or polishing on the flat lower electrode 5. Further, it is possible to form, for example, a convex portion 95 on the flat lower electrode 5 by a thermal spraying method. In this case, the convex portion 95 can also be formed of, for example, a ceramic sprayed film having plasma erosion resistance.

In addition, the convex part 95 in this Embodiment may be provided over the perimeter of mounting area | region R1 of the lower electrode 5 similarly to 1st Embodiment, or 2nd Embodiment. As described above, it may be provided around the corners C1 to C4 of the mounting area R1 or around the centers E3 and E4 of the central part of the long side of the mounting area R1 as in the third embodiment. Further, the height of the convex portion 95 can be set to be equal to or greater than or smaller than the thickness T of the substrate S. Other configurations and effects of the plasma film forming apparatus of the present embodiment are the same as those of the plasma film forming apparatus 100 of the first embodiment, and thus description thereof is omitted.

[Experimental example]
Next, with reference to FIGS. 14 to 18, the experimental results confirming the effect of the present invention will be described. Using a plasma film forming apparatus having the same configuration as the plasma film forming apparatus of the second embodiment, a film forming experiment for forming a microcrystalline silicon thin film on the substrate S by plasma CVD was performed.

(Experimental example 1)
In this experiment, using SiH ₄ and _{H 2} gas as the source gas, the ratio between the flow rate of SiH ₄ gas [SiH _4], the flow rate _{[H 2]} of the _{H 2} gas _{[R] = [H 2]} / [SiH ₄ ] was introduced into the processing container 1 at a flow rate ratio such that 50 or more. The film forming pressure was 1400 Pa. Then, by supplying high frequency power of 11 MHz from the high frequency power source 7 to the upper electrode 3, plasma is generated between the upper electrode 3 and the lower electrode 5, and microcrystalline silicon having a thickness of about 1 μm is formed on the surface of the substrate S. A thin film was formed. The upper electrode 3 has a long side of 1500 mm × a short side of 1160 mm, and the size of the glass substrate is 1400 × 1000 × 4.0 mm. The distance (gap) between the upper electrode 3 and the lower electrode 5 was 15 mm. As an auxiliary plate, the thing similar to the auxiliary plate 91 shown in FIG. 14 was used. The auxiliary plate 91A has a long side of 215 mm × short side of 40 mm, and the auxiliary plate 91B has a long side of 165 mm × short side of 50 mm. The heights of the

auxiliary plates

91A and 91B were both 4 mm, and the same thickness as that of the substrate S was used. Further, as the auxiliary plate 91, an experiment was performed on a ceramic plate and an aluminum plate.

The deposition rate and crystallinity of the microcrystalline silicon film in Experimental Example 1 were measured at 21 points on the substrate S as shown in FIG. The results of the deposition rate are shown in FIG. 15, and the crystallinity data are shown in FIG. The crystallinity was expressed as a ratio Ic / Ia between the amorphous silicon peak Ia (480 cm ⁻¹ ) and the microcrystalline silicon peak Ic (520 cm ⁻¹ ) measured by a Raman spectrophotometer. From FIG. 15, by installing the ceramic auxiliary plate 91 and the aluminum auxiliary plate 91, the deposition rate of the corner portions (measurement points A0, E0, U0, Y0) of the substrate S was remarkably improved. On the other hand, FIG. 16 shows that the crystallinity of the corner portions (measurement points A0, E0, U0, Y0) of the substrate S tends to decrease.

15 and 16, from the corner portion of the substrate S, the deposition rate increased, but the crystallinity decreased, indicating a contradictory tendency. In general, when the gas supply flow rate increases, the deposition rate increases, but the crystallinity tends to decrease. When the supply of high-frequency power increases, both the deposition rate and crystallinity tend to increase. Therefore, in the present experimental example, the effect of the auxiliary plate 91 is dominated by the effect of improving the gas flow at the corner portion of the substrate S. As a result, the deposition rate is improved and the crystallinity is lowered at the corner portion. It is thought that it was caused. Note that the decrease in crystallinity at the corner portion of the substrate S can be corrected by increasing the high-frequency power supplied from the high-frequency power source 7 to the upper electrode 3.

(Experimental example 2)
In this experiment, an aluminum auxiliary plate 91 was used as an auxiliary plate, and the same conditions as in Experimental Example 1 were provided except that high frequency power of 27 MHz, which is generally considered to be difficult for plasma to spread, was supplied from the high frequency power source 7 to the upper electrode 3. I went there. The measurement result of the deposition rate is shown in FIG. 17, and the measurement result of the crystallinity is shown in FIG. From FIG. 17, the deposition rate of the corner portions (measurement points A0, E0, U0, Y0) of the substrate S was remarkably improved by installing the auxiliary plate 91 made of aluminum. In addition, as shown in FIG. 18, the crystallinity of the corner portions (measurement points A0, E0, U0, Y0) of the substrate S was also significantly improved.

FIG. 17 and FIG. 18 show that the deposition rate and the crystallinity tend to be improved in the corner portion of the substrate S. In this experimental example, the auxiliary plate 91 improves the supply of high-frequency power by expanding the gas flow and plasma in the corner portion of the substrate S, so that the deposition rate and crystallinity in the corner portion are improved. It is done.

From the above experimental results, by arranging the auxiliary plate 91 on the lower electrode 5, it is possible to control the film forming process speed (deposition rate and progress of crystallization) in the plane of the substrate S, and It was confirmed that the uniformity of the deposition rate and crystallinity was improved in the plane.

As described above, the embodiments of the present invention have been described in detail for the purpose of illustration, but the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, in the plasma film forming apparatus of the above embodiment, the high frequency power is supplied to the upper electrode 3. However, the high frequency power may be applied using the lower electrode 5 of the pair of parallel plate electrodes as the cathode electrode.

Further, the plasma film forming apparatus may be configured to supply a plurality of high frequency powers having different frequencies to the pair of parallel plate electrodes.

Further, in the above embodiment, the batch type plasma film forming apparatus 100 of FIG. 1 in which a plurality of plasma processing units 10 are stacked in multiple stages is taken as an example, but the present invention is also applied to a single wafer type plasma film forming apparatus. Applicable.

This international application claims priority based on Japanese Patent Application No. 2013-130238 filed on June 21, 2013, the entire contents of which are incorporated herein by reference.

Claims

A processing container capable of being evacuated;
In the processing container, an upper electrode and a lower electrode disposed to face each other,
A high frequency power supply for supplying high frequency power to at least one of the upper electrode or the lower electrode;
With
The lower electrode has a rectangular placement area on which a rectangular substrate is placed, and a non-placement area that is provided adjacent to the outside so as to surround the placement area and does not place the substrate. And
The plasma processing apparatus which provided the convex part in the one part or the whole of the said non-mounting area | region.
The plasma processing apparatus according to claim 1, wherein the convex portion is provided partially around a corner portion of the rectangular placement region.
The upper electrode or the lower electrode has a rectangular shape in plan view,
In the upper electrode or the lower electrode, a feeding portion to which high-frequency power is supplied from the high-frequency power source is provided on a side portion forming the long side of the rectangle,
The plasma processing apparatus according to claim 1, wherein the convex portion is partially provided outside a long side of the rectangular placement region on the same side as the power feeding portion.
The upper electrode or the lower electrode has a rectangular shape in plan view,
In the upper electrode or the lower electrode, a feeding portion to which high-frequency power is supplied from the high-frequency power source is provided on a side portion forming the long side of the rectangle,
2. The plasma processing apparatus according to claim 1, wherein the convex portion is partially provided outside a long side of the rectangular placement region on the opposite side to the power feeding portion.
The plasma processing apparatus according to claim 1, wherein the convex portion is provided so as to surround the whole of the rectangular placement region.
The plasma processing apparatus according to claim 1, wherein the height of the convex portion is the same as the thickness of the substrate placed in the placement area.
The plasma processing apparatus according to claim 1, wherein a height of the convex portion is smaller than a thickness of the substrate placed in the placement area.
The height of the convex portion is relatively high around the corner of the rectangular placement region, and is low at a portion adjacent to the short side or the central portion of the long side of the rectangular placement region. The plasma processing apparatus according to claim 5.
The plasma processing apparatus according to claim 1, wherein the convex portion is provided integrally with the lower electrode.
The plasma processing apparatus according to claim 1, wherein the convex portion is a plate-like member that can be attached to and detached from the lower electrode.
The plasma processing apparatus according to claim 10, wherein the convex portion is made of a dielectric.
The plasma processing apparatus according to claim 10, wherein the convex portion is made of a conductor.
The plasma processing apparatus according to claim 1, wherein the substrate is a glass substrate for a solar cell.
A processing container capable of being evacuated, an upper electrode and a lower electrode arranged opposite to each other in the processing container, and a high-frequency power source for supplying high-frequency power to at least one of the upper electrode or the lower electrode The lower electrode includes a rectangular placement area for placing a rectangular substrate, and a non-placement area provided adjacent to the outside so as to surround the placement area and not placing the substrate. And a plasma processing method for performing plasma processing by mounting the substrate on the mounting region, using a plasma processing apparatus provided with a convex portion on a part or the whole of the non-mounting region.
The plasma processing method according to claim 14, wherein a film forming process is performed on the substrate by a plasma CVD method.