JP2010171244A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus capable of suppressing curving of an electrode. <P>SOLUTION: The plasma processing apparatus includes a vacuum container 100, a cathode electrode 200, an anode electrode 300, and an electrode plate 220. The cathode electrode 200 is arranged in the vacuum container 100, and AC power is input. The anode electrode 300 is arranged in the vacuum container 100 opposite the cathode electrode 200, and a substrate 50 is arranged. The electrode plate 220 is arranged on a surface of at least one of the cathode electrode 200 and anode electrode 300. The electrode plate 220 has a first groove and a second groove in a region superposing the substrate 50 in planar view. The first groove is formed on a first surface of the electrode plate 220 which faces the substrate 50. The second groove is formed on a second surface on the opposite side from the first surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus.

  As a method of forming a silicon-based thin film or a diamond-like carbon thin film, there is a plasma CVD apparatus. The most widely used method among plasma CVD apparatuses is a capacitive coupling method in which a cathode electrode and an anode electrode are made to face each other and plasma is generated between these two electrodes.

  In a capacitively coupled plasma CVD apparatus, the electrode may be distorted due to thermal expansion (for example, Patent Document 1). Patent Document 1 discloses forming a groove so as to surround a shower head in a cathode electrode having a shower head. It is described that the amount of heat that escapes from the shower head to the outside is reduced by this groove, and the temperature distribution across the surface of the shower head can be made more uniform.

Japanese Patent Laid-Open No. 10-144614

  In recent years, there is a tendency that the area where film formation is performed by a single process is increased, and accordingly, the cathode electrode and the anode electrode are also increased in area. For this reason, the technique described in Patent Document 1 cannot sufficiently eliminate the occurrence of warping due to the thermal strain of the electrode. This problem is not limited to plasma CVD, but occurs similarly in a sputtering apparatus and an etching apparatus.

  This invention is made | formed in view of the said situation, The place made into the objective is to provide the plasma processing apparatus which can suppress that curvature generate | occur | produces in an electrode.

According to the present invention, a vacuum vessel;
A cathode electrode disposed in the vacuum vessel and receiving AC power;
An anode electrode disposed in the vacuum container facing the cathode electrode, and a substrate is disposed;
An electrode plate disposed on at least one surface of the cathode electrode and the anode electrode;
With
In the region where the electrode plate overlaps the substrate in plan view,
A first groove formed on a first surface facing the substrate;
There is provided a plasma processing apparatus including a second groove formed on a second surface which is a surface opposite to the first surface.

  According to the present invention, the first groove and the second groove are formed in the electrode plate in a region overlapping the substrate in plan view. For this reason, it can suppress that a curvature arises in an electrode plate.

It is sectional drawing which shows the structure of the plasma processing apparatus which concerns on 1st Embodiment. It is sectional drawing of an electrode plate. Each figure is a diagram showing an example of the arrangement of groove groups when the planar shape of the electrode plate is rectangular or square. Each figure is a diagram showing an example of the arrangement of groove groups when the planar shape of the electrode plate is circular. It is sectional drawing which shows the structure of the plasma processing apparatus which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

  FIG. 1 is a cross-sectional view showing the configuration of the plasma processing apparatus according to the first embodiment. This plasma processing apparatus includes a vacuum vessel 100, a cathode electrode 200, an anode electrode 300, and an electrode plate 220. The cathode electrode 200 is disposed in the vacuum vessel 100 and receives AC power. The anode electrode 300 is disposed in the vacuum vessel 100 so as to face the cathode electrode 200, and the substrate 50 is disposed. The electrode plate 220 is disposed on at least one surface of the cathode electrode 200 and the anode electrode 300. The electrode plate 220 includes a first groove 224 (shown in FIG. 2) and a second groove 226 (shown in FIG. 2) in a region overlapping the substrate 50 in plan view. The first groove 224 is formed on the first surface of the electrode plate 220 facing the substrate 50. The second groove 226 is formed on the second surface which is the surface opposite to the first surface. The second groove 226 preferably extends in parallel with the first groove 224.

  In the present embodiment, the electrode plate 220 is disposed on the surface of the cathode electrode 200. The cathode electrode 200 is a shower head that supplies process gas into the vacuum vessel 100. The electrode plate 220 has a plurality of through holes 222 through which the process gas supplied via the pipe 210 is introduced into the vacuum vessel 100. AC power, for example, high frequency power of 13 MHz to 100 MHz is input to the cathode electrode 200 from the high frequency power supply 400. The anode 300 is provided with a heater (not shown) for heating the substrate 50.

  This plasma processing apparatus is an apparatus that performs a film forming process on the substrate 50 by, for example, a plasma CVD method. The film to be formed is a semiconductor film containing Si, for example, a microcrystalline silicon layer or an amorphous silicon layer as a photoelectric conversion layer of a thin film solar cell. The photoelectric conversion layer is formed by stacking silicon layers of the first conductivity type, i-type, and second conductivity type. In this case, the process gas includes at least one selected from the group consisting of silane, disilane, hydrogen, diborane, and phosphine. The substrate 50 may be a wafer-like substrate or a flexible substrate. In the latter case, the substrate 50 may be transported to the plasma processing apparatus in a roll-to-roll manner.

  FIG. 2 is a cross-sectional view of the electrode plate 220. As described above, the electrode plate 220 includes the through hole 222 for introducing the process gas into the vacuum vessel 100, the first groove 224, and the second groove 226. The first groove 224 and the second groove 226 are arranged so as not to overlap in plan view, and the depth is not less than half the thickness t of the electrode plate 220. That is, when viewed from the side surface of the electrode plate 220, the first groove 224 and the second groove 226 have the tip portions overlapping each other. The widths of the first groove 224 and the second groove 226 are both 0.5 mm or more.

  The first groove 224 and the second groove 226 extend in parallel to each other to form one groove group 228. The groove group 228 preferably extends so as not to overlap with the through hole 222, but may overlap with the through hole 222. In one groove group 228, the first groove 224 and the second groove 226 are arranged close to each other, and the interval L is equal to or less than the thickness t of the electrode plate 220, but the strength of the electrode plate 220 is increased. From the viewpoint of ensuring, it is preferable that the difference is not less than the difference between the thickness t and the depth of the groove 228. In the example shown in the figure, one groove group 228 is formed with one first groove 224 and two second grooves 226. The two second grooves 226 are disposed so as to sandwich the first groove 224 in plan view.

  3 is a diagram illustrating an arrangement example of the groove group 228 when the planar shape of the electrode plate 220 is a rectangle or a square. In each diagram of FIG. 4, the planar shape of the electrode plate 220 is a circle. It is a figure which shows the example of arrangement | positioning of the groove group 228 in a case. In these drawings, the through hole 222 is omitted.

  In each of FIGS. 3 and 4, (a) shows an example in which a plurality of groove groups 228 extend in parallel with each other at equal intervals, and (b) shows that the groove groups 228 extend in a lattice shape. An example is shown. Further, (c) shows an example in which the groove group 228 is provided along each of a plurality of circles having a diameter different from each other with the center of the electrode plate 220 as the center, and (d) is shown in (c). In addition to the above example, an example in which the groove group 228 is further provided along at least one straight line passing through the center of the electrode plate 220 is shown. Specifically, in (d), the groove group 228 is provided along two straight lines that are orthogonal to each other in addition to the example shown in (c). The intersection of these two straight lines overlaps the center of the electrode plate 220. In the example shown in (b), the groove group 228 is preferably provided symmetrically with the center of the electrode plate 220 as the center.

  Next, the operation and effect of this embodiment will be described. In the plasma processing, the electrode plate 220 receives heat from the plasma, so that the temperature rises. In particular, when the electrode plate 220 is provided on the cathode electrode 200, the electrode plate 220 is directly exposed to plasma, so that it tends to be at a high temperature. On the other hand, the heat around the electrode plate 220 escapes to the portion holding the electrode plate 220. For this reason, heat distribution is generated in the central portion and the peripheral portion of the electrode plate 220, and thermal stress is generated in the electrode plate 220. In addition, when the treatment in the plasma processing apparatus is a film formation treatment, a film is attached to the surface of the electrode plate 220, and thus stress is generated on the electrode plate 220 due to the film. When stress is generated in the electrode plate 220, the electrode plate 220 is warped, and the distance between the cathode electrode 200 and the anode electrode 300 is distributed. This tendency became more prominent as the electrode plate 220 increased in area.

  On the other hand, in the present embodiment, the first groove 224 and the second groove 226 are formed in the electrode plate 220 in a region overlapping the substrate 50 in plan view. For this reason, even if stress is generated in the electrode plate 220, this stress can be absorbed by the first groove 224 and the second groove 226. Accordingly, it is possible to suppress the distribution from occurring in the distance between the cathode electrode 200 and the anode electrode 300.

  Further, since the first groove 224 is formed on the first surface of the electrode plate 220 and the second groove 226 is formed on the second surface, the electrode plate 220 is formed on the first surface when stress is absorbed. Alternatively, warping in any direction of the second surface is suppressed. This effect is particularly remarkable when the second groove 226 extends in parallel with the first groove 224.

  Further, since the depth of the first groove 224 and the second groove 226 is more than half of the thickness of the electrode plate 220, when viewed from the side of the electrode plate 220, the tips of the first groove 224 and the second groove 226 The parts overlap each other. Therefore, when viewed in the thickness direction of the electrode plate 220, stress is absorbed by at least one of the first groove 224 and the second groove 226 in any part of the electrode plate 220.

  In addition, as shown in FIG. 2, in this embodiment, since a plurality of second grooves 226 are formed on the surface opposite to the surface exposed to plasma, the ability to absorb stress is increased. Further, the number of the second grooves 226 is larger than that of the first grooves 224 formed on the surface exposed to the plasma. For this reason, the number of the 1st groove | channels 224 which may be filled with a film | membrane among the 1st groove | channel 224 and the 2nd groove | channel 226 which have stress absorption capability can be decreased.

  Further, the above-described thermal stress or film stress tends to occur symmetrically with the center of the electrode plate 220 as the center. For this reason, when the groove group 228 is provided symmetrically about the center of the electrode plate 220, it is possible to suppress the stress from remaining in a specific portion.

  FIG. 5 is a cross-sectional view showing the configuration of the plasma processing apparatus according to the second embodiment. The example shown in this figure has the same configuration as that of the first embodiment except that an electrode plate 310 is provided on the surface of the anode electrode 300. The configuration of the electrode plate 310 is the same as that of the electrode plate 220 shown in the first embodiment, except that the through-hole 222 is not provided. The substrate 50 is placed on the electrode plate 310. A conductive spacer (not shown) may be provided between the electrode plate 310 and the main body of the anode electrode 300.

  Also according to this embodiment, the same effect as that of the first embodiment can be obtained. Further, since the anode electrode 300 is heated by a heater (not shown), a large thermal stress is likely to occur. On the other hand, in this embodiment, since the surface of the anode electrode 300 is formed by the electrode plate 310, it can suppress that the surface of the anode electrode 300 warps. Accordingly, it is possible to further suppress the distribution in the distance between the cathode electrode 200 and the anode electrode 300.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable. For example, in the second embodiment, the first groove 224 and the second groove 226 need not be provided in the electrode plate 220. Further, the processing performed by the plasma processing apparatus is not limited to plasma CVD, but may be sputtering or dry etching.

Example 1
In the plasma processing apparatus shown in the first embodiment, the cathode electrode 200 and the anode electrode 300 have a square shape with a side of 250 mm. As the electrode plate 220, an aluminum alloy plate having a thickness t of 2 mm was used. As the arrangement of the groove groups 228, as shown in FIG. 3B, the interval between the adjacent groove groups 228 was set to 50 mm. The depth of the 1st groove | channel 224 and the 2nd groove | channel 226 was 1.5 mm, and the width | variety was 1 mm. The distance L between the first groove 224 and the second groove 226 was 0.7 mm.

  In the plasma processing apparatus described above, 30 sccm of silane gas and 2000 sccm of hydrogen gas were introduced into the vacuum vessel 100 through the cathode electrode 200. The pressure in the vacuum vessel 100 was 3 Torr, and the temperature of the anode electrode 300 was set to 200 ° C. In this state, a high frequency of 27 MHz was input to the cathode electrode 200 at 500 W to generate plasma in the space between the cathode electrode 200 and the anode electrode 300 to perform film formation. The film formation process was performed in three times for a total of 25 hours. The thickness of the film formed under these conditions is 230 μm when converted from the film forming speed.

  After the film formation process, the electrode plate 220 of the cathode electrode 200 was taken out into the atmosphere and the warpage was measured. As a result, the warpage was 0.1 mm or less.

(Comparative Example 1)
Using the electrode plate 220 in which the first groove 224 and the second groove 226 are not formed, a film forming process was performed under the same conditions as in Example 1 and copper. And after the film-forming process, the electrode plate 220 of the cathode electrode 200 was taken out in air | atmosphere, and curvature was measured. As a result, the warpage was about 0.6 mm. This warpage is considered to be caused by the film formed.

  As described above, it has been shown that by forming the first groove 224 and the second groove 226, the warpage generated in the electrode plate 220 due to the formed film is reduced. In addition, during the film forming process, that is, while the heat is applied to the electrode plate 220, it is considered that the electrode plate 220 is warped due to the heat. Even in this case, the same result is obtained. Presumed.

(Example 2)
On the surface of the anode electrode 300, an electrode plate 310 having the same configuration as the electrode plate 220 shown in Example 1 was disposed. At this time, a space of 0.5 mm was provided between the surface of the anode electrode 300 and the electrode plate 310. Then, the anode electrode 300 was heated to 200 ° C. in the atmosphere, and the height difference, that is, the warpage between the central portion and the peripheral portion of the electrode plate 310 at this time was measured. As a result, the warpage was 0.2 mm.

(Comparative Example 2)
Using the electrode plate 310 in which the first groove 224 and the second groove 226 were not formed, the same processing as in Example 2 was performed. As a result, the warpage was 0.8 mm.

  As described above, it has been shown that the warpage generated in the electrode plate 310 due to heat is reduced by forming the first groove 224 and the second groove 226.

50 Substrate 100 Vacuum container 200 Cathode electrode 210 Pipe 220 Electrode plate 222 Through hole 224 First groove 226 Second groove 228 Groove group 300 Anode electrode 310 Electrode plate 400 High frequency power supply

Claims (12)

A vacuum vessel;
A cathode electrode disposed in the vacuum vessel and receiving AC power;
An anode electrode disposed in the vacuum container facing the cathode electrode, and a substrate is disposed;
An electrode plate disposed on at least one surface of the cathode electrode and the anode electrode;
With
In the region where the electrode plate overlaps the substrate in plan view,
A first groove formed on a first surface facing the substrate;
A plasma processing apparatus comprising: a second groove formed on a second surface which is a surface opposite to the first surface. The plasma processing apparatus according to claim 1,
The plasma processing apparatus, wherein the second groove extends parallel to the first groove. The plasma processing apparatus according to claim 1 or 2,
The plasma processing apparatus, wherein the depth of the first groove and the second groove is more than half of the thickness of the electrode plate. In the plasma processing apparatus as described in any one of Claims 1-3,
A plasma processing apparatus, wherein a distance between the first groove and the second groove is equal to or less than a thickness of the electrode plate in a plan view. In the plasma processing apparatus according to any one of claims 1 to 4,
The width of the first groove and the second groove is a plasma processing apparatus in which both are 0.5 mm or more. In the plasma processing apparatus according to any one of claims 1 to 5,
The cathode plate is provided with the electrode plate;
The plasma processing apparatus, wherein the electrode plate has a plurality of through holes for supplying a process gas into the vacuum vessel. In the plasma processing apparatus according to any one of claims 1 to 6,
The plasma processing apparatus, wherein the electrode plate is provided with a groove group including the first groove and the second groove along each of a plurality of circles having a diameter different from each other around the center of the electrode plate. The plasma processing apparatus according to claim 7, wherein
The plasma processing apparatus, wherein the electrode plate is further provided with the groove group along at least one straight line passing through a center of the electrode plate. In the plasma processing apparatus according to any one of claims 1 to 6,
The plasma processing apparatus, wherein a groove group including the first groove and the second groove extends in a lattice shape on the electrode plate. In the plasma processing apparatus according to any one of claims 1 to 6,
The plasma processing apparatus, wherein a plurality of groove groups each including the first groove and the second groove extend parallel to each other on the electrode plate. In the plasma processing apparatus as described in any one of Claims 1-10,
A plasma processing apparatus in which a film forming process is performed on the substrate in the vacuum container. The plasma processing apparatus according to claim 11, wherein
The film formed by the film forming process is a plasma processing apparatus which is a photoelectric conversion layer of a thin film solar cell.

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