JP2008277583A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus capable of simplifying the configuration of the apparatus and generating uniform plasma even if using a high-frequency power supply. <P>SOLUTION: The plasma processing apparatus 10 comprises: a substrate arrangement electrode 21 capable of arranging a substrate 20 to be treated; a counter electrode 22 arranged oppositely nearly in parallel with the substrate arrangement electrode 21 and made of a conductive material so that an AC voltage can be applied to a side opposite to the substrate arrangement electrode 21; and a plate member 35 arranged between the counter electrode 22 and the substrate arrangement electrode 21 and made of a dielectric material. In this case, the plate member 35 is formed so that treatment gas supplied between the plate member 35 and the counter electrode 22 is jetted out of a plurality of gas exhaust ports 36 formed in the plate member 35 toward the substrate arrangement electrode 21. A through hole 50 is formed in the counter electrode 22. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus.

In recent years, attempts have been made to increase the plasma excitation frequency in order to increase the plasma density and reduce the electron energy. For example, an amorphous silicon thin film of a thin film solar cell is manufactured by plasma CVD using capacitively coupled plasma on parallel plates driven at 13.56 MHz. When the frequency is further increased, the electron energy in the plasma is reduced, so that the Si—H ₂ polymerization reaction generated during the amorphous silicon film formation can be suppressed, and a high quality film is formed.

  However, increasing the plasma excitation frequency causes the voltage distribution in the electrode surface to deteriorate due to standing waves, resulting in non-uniform plasma distribution. Therefore, it is difficult to increase the area of the electrode corresponding to the increase in the size of the substrate. Specifically, since the glass substrate used for manufacturing a liquid crystal display or a thin film solar cell is rectangular, the electrode is also rectangular, but in the case of a rectangular electrode, plasma density at the four corners is significantly reduced in plasma CVD. There was a problem.

  For this reason, for example, in a plasma apparatus having a large electrode with a side exceeding 2 m, the frequency is generally 13.56 MHz, and higher frequencies (27.12 MHz, 40.68 MHz, etc.) are used. I couldn't.

Therefore, in order to solve this problem, there is a high-frequency plasma generator capable of generating uniform plasma in a large area and performing uniform processing for large substrates in plasma CVD using high frequency. It has been proposed (see, for example, Patent Document 1). This high-frequency plasma generation apparatus is a method for supplying power to a discharge electrode for generating a discharge state based on high-frequency power supplied to the discharge electrode, using high-frequency power sources that are independent of each other with high frequencies having different oscillation frequencies, The generation of standing waves is suppressed by the difference in frequency of each power source.
JP 2001-274099 A

  By the way, in the above-described high-frequency plasma generation apparatus, since a plurality of high-frequency power sources are used to apply a voltage to the electrodes while changing the phase of each to generate uniform plasma, the control is complicated and the apparatus is excessively expensive. It was necessary to apply. Therefore, there is a problem that mass production of the apparatus is difficult.

  Therefore, the present invention has been made in view of the above circumstances, and can provide a plasma processing apparatus that can simplify the configuration of the apparatus and can generate uniform plasma even when a high-frequency power source is used. It is to provide.

  The invention described in claim 1 is configured such that a substrate placement electrode on which a substrate to be processed can be placed, and a substrate placement electrode that is disposed substantially parallel to the substrate placement electrode, and an AC voltage can be applied to the opposite side of the substrate placement electrode. A counter electrode made of a conductive material, and a plate-like member made of a dielectric material, disposed between the counter electrode and the substrate placement electrode, the plate-like member comprising: In the plasma processing apparatus formed so that the processing gas supplied between the counter electrode and the counter electrode may be ejected from a plurality of gas ejection ports formed in the plate member toward the substrate arrangement electrode. A feature is that a through-hole is formed in the electrode.

By comprising in this way, since the electromagnetic wave of the alternating voltage applied to the counter electrode can propagate through a through-hole, the electric field strength in the formation position of a through-hole can be raised. Therefore, by adjusting the position of the through hole, the voltage distribution on the back surface of the counter electrode can be adjusted, so that the electric field strength on the back surface of the counter electrode can be made uniform. As a result, there is an effect that uniform plasma can be generated.
Moreover, since it can implement | achieve only by forming a through-hole in a counter electrode, there exists an effect which can simplify the structure of an apparatus.

  According to a second aspect of the present invention, the counter electrode is formed in a rectangular shape in plan view, and feeding points to which the AC voltage is applied are provided at positions closer to the four corners than the center point of the counter electrode. It is characterized by being.

  With this configuration, the voltage distribution at positions close to the four corners in the rectangular counter electrode can be adjusted, and the electric field strength on the back surface of the counter electrode can be made uniform. Therefore, there is an effect that uniform plasma can be generated.

  The invention described in claim 3 is characterized in that the through hole is formed only in a predetermined region including the feeding point.

  With such a configuration, the electric field strength at the back surface position corresponding to the feeding point of the counter electrode can be reliably increased, so that there is an effect that more uniform plasma can be generated.

  The invention described in claim 4 is characterized in that a formation density of the through holes in a predetermined region including the feeding point is higher than a formation density of the through holes outside the predetermined region.

  By configuring in this way, the electric field strength at the back surface position corresponding to the feeding point of the counter electrode can be reliably increased, and the electric field strength at the back surface of the counter electrode can be freely adjusted, so that it is more uniform. There is an effect that it is possible to generate a plasma.

  The invention described in claim 5 is characterized in that the through hole is formed only in a predetermined region including a corner of the counter electrode.

  With this configuration, the electric field strength in a predetermined region near the corner of the counter electrode can be increased regardless of the position of the feeding point. Therefore, there is an effect that uniform plasma can be generated.

  The invention described in claim 6 is characterized in that a formation density of the through holes in a predetermined region including a corner portion of the counter electrode is higher than a formation density of the through holes outside the predetermined region. .

  With such a configuration, electromagnetic waves can be propagated along the through holes in a predetermined region near the corner of the counter electrode, so that the electric field strength in the predetermined region can be increased. Therefore, there is an effect that uniform plasma can be generated.

  In a seventh aspect of the present invention, a plate member made of a dielectric material is attached to a surface of the counter electrode that faces the plate-like member, and the through hole of the counter electrode is blocked by the plate member. It is characterized by that.

  By comprising in this way, since the through-hole formed in the counter electrode by the plate member can be closed, the processing gas supplied between the plate-shaped member and the counter electrode does not leak from the through-hole. There is an effect that the gas can be reliably supplied from the gas outlet toward the substrate arrangement electrode.

  The invention described in claim 8 is characterized in that the through hole of the counter electrode is closed by an embedded member made of a dielectric.

  With this configuration, the through hole formed in the counter electrode can be closed by the embedded member, so that the processing gas supplied between the plate member and the counter electrode leaks from the through hole. And there is an effect that the gas can be reliably supplied from the gas outlet toward the substrate arrangement electrode.

According to the present invention, an electromagnetic wave of an alternating voltage applied to the counter electrode can propagate through the through hole, so that the electric field strength at the position where the through hole is formed can be increased. Therefore, since the voltage distribution on the back surface of the counter electrode can be adjusted by adjusting the positions of the feeding point and the through hole, the electric field strength on the back surface of the counter electrode can be made uniform. As a result, there is an effect that uniform plasma can be generated.
Moreover, since it can implement | achieve only by forming a through-hole in a counter electrode, there exists an effect which can simplify the structure of an apparatus.

(First embodiment)
(Deposition system)
Next, a first embodiment of the present invention will be described with reference to FIGS. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

FIG. 1 is a schematic configuration diagram of a film forming apparatus in the present embodiment.
As shown in FIG. 1, a film forming apparatus 10 that performs a plasma CVD method has a bottomed cylindrical vacuum chamber 11. The vacuum chamber 11 is made of a conductive material such as aluminum. The vacuum chamber 11 is grounded and configured to be able to maintain a ground potential. Further, an insulating flange 13 made of an insulating material is provided on the opening peripheral edge 12 of the vacuum chamber 11. A lid 15 that functions as a shield cover is provided so as to be connected to the vacuum chamber 11. That is, the vacuum chamber 11 and the lid 15 are configured to have a box shape. Further, the insulating flange 13 can reliably insulate the vacuum chamber 11 held at the ground potential from the counter electrode 40 to which an AC voltage is applied.

  A support column 17 is disposed below the vacuum chamber 11 so as to pass through the bottom 16 of the vacuum chamber 11, and the tip of the support column 17 (inside the vacuum chamber 11) is connected to the bottom surface 19 of the plate-like heater base 18. Has been. Moreover, the support | pillar 17 is connected to the raising / lowering mechanism not shown provided in the exterior of the vacuum chamber 11, and is comprised so that a vertical movement is possible. That is, the heater base 18 connected to the tip of the support column 17 and the substrate table 21 on which the substrate 20 is placed can be moved up and down. A bellows 23 is provided outside the vacuum chamber 11 so as to cover the periphery of the column 17.

  The heater base 18 is a plate-like member having a flat surface, and the substrate table 21 is placed on the upper surface thereof. The heater base 18 is formed of a conductive material made of a nickel-based alloy such as Inconel (registered trademark), for example. The heater base 18 only needs to be rigid and have corrosion resistance and heat resistance.

  The substrate table 21 is a plate-like member having a flat surface, similar to the heater base 18, and the substrate 20 is placed on the upper surface thereof. The substrate table 21 is formed of a conductive material such as an aluminum alloy, for example. Since the substrate table 21 functions as a ground electrode, a conductive one is employed.

  The substrate table 21 includes a heater wire 22 therein, and is configured to be temperature adjustable. The heater wire 22 is drawn out from the bottom surface of the substrate table 21 at a substantially central portion in plan view, and is inserted through a through-hole 26 and a column 17 formed in the substantially central portion of the heater base 18 in plan view. 11 to the outside. The heater wire 22 is connected to a power source (not shown) outside the vacuum chamber 11 so that the temperature is adjusted.

  A plurality of ground plates 25 are arranged at substantially equal intervals in plan view so as to connect between the heater base 18 and the vacuum chamber 11. The ground plate 25 is formed of a flexible metal plate, and is made of, for example, a nickel-based alloy or an aluminum alloy. That is, since the heater base 18 and the vacuum chamber 11 are electrically connected and the vacuum chamber 11 is held at the ground potential, the heater base 18 and the substrate table 21 placed on the heater base 18 are also grounded. It is comprised so that it may be hold | maintained.

  A cleaning gas introduction pipe 27 is connected to the vacuum chamber 11. The cleaning gas introduction pipe 27 is provided with a fluorine-based gas supply unit 28 and a radical source 29. The fluorine gas supplied from the fluorine-based gas supply unit 28 is decomposed by the radical source 29, and the fluorine radicals generated thereby are It is configured to be supplied to the film forming space in the vacuum chamber 11. That is, when the film formation on the substrate 20 is repeated several times, the film formation material attached to the inner wall surface of the vacuum chamber 11 can be removed by a chemical reaction.

  Further, an exhaust pipe 31 is connected to the vacuum chamber 11, and a vacuum pump 32 is provided at the tip thereof so that the inside of the vacuum chamber 11 can be decompressed.

  Here, a shower plate 35 is provided in the vacuum chamber 11 so as to face the substrate table 21. The shower plate 35 is made of a dielectric material such as alumina. The shower plate 35 is provided with a large number of gas outlets 36. Furthermore, a wall portion 37 is formed on the peripheral edge of the shower plate 35 over the entire circumference.

  A plate-like counter electrode 40 is provided so as to cover the wall portion 37 of the shower plate 35. The counter electrode 40 is formed of a conductive material such as an aluminum alloy, for example. The shower plate 35 and the counter electrode 40 are connected to each other to form a box shape. That is, a space 41 is formed between the shower plate 35 and the counter electrode 40. The shower plate 35 and the counter electrode 40 are attached to the vacuum chamber 11 via the insulating flange 13.

Furthermore, a dielectric plate 42 formed of a dielectric material such as alumina is provided on the surface (back surface 62) of the counter electrode 40 on the space 41 side so as to cover the entire back surface 62.
The distance between the dielectric plate 42 and the shower plate 35, that is, the distance in the vertical direction of the space 41 is configured to be, for example, about 5 mm or less so that plasma does not discharge in the space 41.

A gas introduction pipe 43 is connected to the counter electrode 40, and a source gas (for example, SiH ₄ ) can be supplied to the space 41 from a film forming gas supply unit 45 provided outside the vacuum chamber 11. Has been. The gas introduction tube 43 extends from the connection portion with the counter electrode 40 through the lid body 15 to the outside of the vacuum chamber 11 and is connected to the film forming gas supply portion 45. The film forming gas introduced into the space 41 is configured to be ejected from the gas ejection port 36 into the vacuum chamber 11.

  When the substrate 20 is disposed on the substrate table 21, the substrate 20 and the shower plate 35 are configured to be close to each other and positioned in parallel. When the deposition gas is ejected from the gas ejection port 36 with the substrate 20 placed on the substrate table 21, the deposition gas is sprayed onto the surface of the substrate 20.

  Further, a power line 49 from an RF power source (high frequency power source) 47 provided outside the vacuum chamber 11 is connected to the surface 61 of the counter electrode 40. Here, the power supply line 49 is connected to the surface 61 of the counter electrode 40 at a plurality of locations (four locations in the present embodiment). A connection point between the counter electrode 40 and the power supply line 49 is configured as a feeding point 57. That is, a high frequency voltage can be applied to a plurality of locations of the counter electrode 40. The feeding point 57 is provided at a position closer to the four corners than the center point 51 of the rectangular counter electrode 40.

(Through hole)
FIG. 2 is a plan view of the counter electrode 40. In the following description, an XYZ orthogonal coordinate system is set, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. The predetermined direction in the horizontal plane is the X-axis direction, the direction orthogonal to the X-axis direction in the horizontal plane is the Y-axis direction, and the direction orthogonal to each of the X-axis direction and the Y-axis direction (that is, the vertical direction) is the Z-axis direction. To do. A through hole for connecting the gas introduction pipe 43 is not shown.

As shown in FIG. 2, the counter electrode 40 is formed in a rectangular shape larger than the outer shape of the substrate 20 in plan view. Note that the peripheral edge portion of the counter electrode 40 is set so that one side thereof is parallel to the X-axis direction, and the side perpendicular thereto is set to be parallel to the Y-axis direction.
A plurality of through holes 50 are formed in the vicinity of the four corners of the counter electrode 40, and a through hole group 55 is formed at each of the four corners. Specifically, a description will be given of one region in which the counter electrode 40 is divided into two in the X-axis direction and the Y direction, and the counter electrode 40 is divided into four equal parts. In one of the four divided regions, the through hole 50 is formed only in the first region 71 including the feeding point 57 and the corner of the counter electrode 40, and the through hole 50 is formed in the other second region 72. Not formed. That is, the through hole group 55 is formed in the first region 71. The through-hole groups 55 are formed at positions (four corners) that are symmetrical with respect to the center point 51 in plan view of the counter electrode 40.

  Here, the through-hole 50 has a rectangular shape in plan view. In addition, the rectangular through hole 50 has a first through hole 50a formed so that the major axis direction thereof is parallel to the X axis direction, and the first through hole 50a formed such that the major axis direction thereof is parallel to the Y axis direction. It is configured with either of the two through holes 50b.

Next, the configuration of the through hole 50 and the through hole group 55 formed in the counter electrode 40 will be described in detail with reference to FIG.
FIG. 3 is a detailed view of part A of FIG.
As shown in FIG. 3, a plurality of first through holes 50 a are formed at equal intervals along the Y-axis direction (in this embodiment, seven locations (see FIG. 2)), and along the X-axis direction. A plurality of intervals are formed (in this embodiment, six locations (see FIG. 2)). That is, the first through holes 50a are arranged at equal intervals so as to leave a gap a with the first through holes 50a adjacent along the Y-axis direction, and are adjacent along the X-axis direction. 50a and gap b are arranged at equal intervals.

  The second through hole 50b is formed in a region 52 formed by the gap a and the gap b so that the center of the region 52 and the center position of the second through hole 50b coincide with each other. Similarly, an array is formed at equal intervals along the Y-axis direction and the X-axis direction (in this embodiment, six locations in the Y-axis direction and seven locations in the X-axis direction (see FIG. 2)). That is, the outer shape of the through-hole group 55 formed by the first through-hole 50a and the second through-hole 50b is substantially square.

Returning to FIG. 2, the center point of one through-hole group 55 is configured as a high-frequency voltage feeding point 57 from the RF power source 47. A power supply line 49 is connected to the feeding point 57.
In the vicinity of the four corners of the counter electrode 40, through hole groups 55 are respectively formed. The feeding point 57 is provided at the center point of the through hole group 55 formed in the first region 71 including the corner of the counter electrode 40. The through hole 50 is not formed in the second region 72 other than that. That is, the through hole group 55 is formed only in the first region 71 including the feeding point 57.

  The configuration of the through-hole group 55 described above is configured in the same manner at the four corners of the counter electrode 40. Therefore, the counter electrode 40 is configured to be fed from four locations. Here, one RF power supply 47 is individually provided for each feeding point 57. It should be noted that a single RF power supply 47 may be used for all the power supply points 57 so that a voltage can be applied collectively, or a single RF power supply 47 can apply voltage to two power supply points 57. May be configured to be able to be applied.

(Function)
Next, an operation when a film is formed on the substrate 20 using the film forming apparatus 10 will be described.
Returning to FIG. 1, in order to form a thin film on the surface of the substrate 20 using the film forming apparatus 10 having the above configuration, first, the vacuum chamber 11 is evacuated by the vacuum pump 32. The substrate 20 is carried into the vacuum chamber 11 and placed on the substrate table 21 while maintaining the vacuum chamber 11 in a reduced pressure state. Here, before the substrate 20 is placed, the substrate table 21 is positioned below the vacuum chamber 11. That is, the distance between the substrate table 21 and the shower plate 35 is wide, and the substrate 20 is held in a state where it can be easily placed on the substrate table 21.

  Then, after the substrate 20 is placed on the substrate table 21, a lifting device (not shown) is activated and the support column 17 is pushed upward, and the substrate 20 placed on the substrate table 21 is also moved upward accordingly. It moves and the space | interval with the shower plate 35 is hold | maintained at the appropriate distance for performing film-forming. Thereafter, a film forming gas (raw material gas) is introduced into the space 41 from the gas introduction pipe 43, and the film forming gas is ejected into the vacuum chamber 11 from the gas ejection port 36 of the shower plate 35. Here, since the through hole 50 formed in the counter electrode 40 is closed by the dielectric plate 42, the deposition gas is surely ejected from the gas ejection port 36.

  With the vacuum chamber 11 connected to the ground potential, the RF power supply 47 is activated to apply a high frequency voltage to the surface 61 of the counter electrode 40 in the vacuum chamber 11. That is, the substrate table 21 electrically connected to the vacuum chamber 11 functions as a ground electrode, and a high frequency voltage is applied between the counter electrode 40 and the substrate table 21 to cause discharge, and the shower plate 35 and the substrate 20 are discharged. Plasma is generated between the surface and the surface. The deposition gas is decomposed in the plasma generated in this way, and a vapor phase growth reaction occurs on the surface of the substrate 20, whereby a thin film is formed on the surface of the substrate 20.

  The substrate 20 is heated to a predetermined temperature (200 to 450 ° C.) in advance by the heater action of the substrate table 21 in the vacuum chamber 11. When the activated film forming gas reaches the surface of the substrate 20, the substrate 20 is heated to The film forming gas reacts to deposit reaction products on the surface of the substrate 20.

  Here, when a high frequency voltage is applied to four feeding points 57 on the surface 61 of the counter electrode 40, the electromagnetic wave propagates through the surface 61 of the counter electrode 40, and from the surface 61 to the back surface 62 at the peripheral edge of the counter electrode 40. And those that propagate along the through hole 50 of the counter electrode 40 from the front surface 61 to the back surface 62 are mixed. Thereby, the electric field intensity near the four corners generated on the back surface 62 of the counter electrode 40 can be increased.

  This is because, at the position of the back surface 62 of the counter electrode 40 corresponding to the feeding point 57, the electromagnetic wave propagating through the through hole 50 is synthesized without phase shift, so that the electric field strength is increased at that position. Therefore, it is possible to suppress a decrease in electric field strength at the four corners of the counter electrode 40. That is, nonuniformity of plasma generated between the shower plate 35 and the substrate 20 can be suppressed, and film formation can be performed without causing uneven film formation on the substrate 20.

(simulation result)
Next, the simulation result about the effect at the time of forming a through-hole in a counter electrode is demonstrated.
FIG. 4 is a plan view of the counter electrode used in the simulation, and FIG. 5 is an enlarged view of a portion B in FIG. FIG. 6 is a comparison diagram of electric field strength when power is supplied to the counter electrode.
As shown in FIG. 4, the counter electrode 65 is a rectangular plate-like member having a size of 2050 mm × 2450 mm in plan view. The through-hole group 66 was formed in one area of the counter electrode 65 which was divided into four equal parts in the X-axis direction and the Y-axis direction. The through-hole group 66 was formed in an array substantially the same as that in the first embodiment described above.

  As shown in FIG. 5, the size of one through-hole 67 is 80 mm × 20 mm, and the X-axis direction and Y-axis direction ( The first through hole 50a and the second through hole 50b) are also configured. The dielectric constant of the through hole 67 was calculated as ε = 1 (equivalent to air).

In this way, a high frequency voltage of 27.12 MHz is supplied to the center point 68 of the counter electrode 65 in which the through-hole group 66 is formed. The electric field strength in the direction along the central axis 69 of the short side of the counter electrode 65 at this time is shown in FIG. The center point 68 is a position in the long side direction of 0 mm.
On the other hand, FIG. 6B shows the electric field intensity at the same central axis 69 as described above when a high-frequency voltage is supplied to the center point of the counter electrode where the through-hole group 66 is not formed.

  Comparing FIG. 6A and FIG. 6B, it can be seen that in FIG. 6B, the electric field strength is maximum at a position corresponding to the center point 68, and the electric field strength decreases as the distance from the center point 68 increases. This is because the electromagnetic wave of the high-frequency voltage applied to the center point 68 propagates radially from the front surface to the back surface of the counter electrode 65, and reaches the electromagnetic wave at the center point on the back surface without causing a phase shift. In the peripheral portion, the arrival time of the electromagnetic wave varies, and the electric field strength becomes weak due to the phase shift.

  On the contrary, in (A), it can be seen that a substantially uniform electric field strength can be obtained on the central axis 69. That is, when the through-hole group 66 is formed in the counter electrode 65, the electric field strength when a high frequency voltage is applied can be made uniform over substantially the entire surface of the counter electrode 65. Accordingly, since plasma is generated substantially uniformly, the film can be uniformly formed on the substrate arranged to face the counter electrode 65. Further, it can be seen from this result that the electric field strength can be adjusted substantially uniformly by forming the through hole 67 in the counter electrode 65 even if the feeding point is not the center point of the through hole group 66.

Next, as another aspect of the present embodiment, a counter electrode can be configured as shown in FIG.
FIG. 7 is a plan view of another aspect of the counter electrode in the present embodiment.
As shown in FIG. 7, a plurality of through holes 81 are formed in the vicinity of the four corners of the counter electrode 80, and a through hole group 83 is formed. The through-hole groups 83 are formed at positions symmetrical with respect to the center point 85 in plan view of the counter electrode 80.

  Here, the through-hole 81 has a circular shape in plan view. The center point of the through-hole group 83 is configured as a high-frequency voltage feeding point 57 from the RF power source 47. A plurality of through holes 81 are formed so as to be symmetric with respect to the X axis and the Y axis with the feeding point 57 as the center, and a through hole group 83 is configured. By comprising in this way, the effect substantially the same as the case of the above-mentioned rectangular through-hole is acquired.

  In addition, in the through hole 81, electromagnetic waves are more easily propagated to the through hole 81 when the aspect ratio calculated by (width of the through hole 81) / (thickness of the counter electrode 40) is larger in the cross section along the Z-axis direction. By making the through-hole 81 circular, it is easy to set the aspect ratio large, so that the electric field strength immediately below the feeding point 57 can be further increased.

  According to the present embodiment, a substrate table (substrate placement electrode) 21 on which a substrate 20 can be placed, and a substrate placement table 21 are arranged so as to face each other substantially parallel, and an AC voltage can be applied to the opposite side of the substrate table 21. A counter electrode 22 made of a conductive material and a shower plate 35 made of a dielectric material disposed between the counter electrode 22 and the substrate table 21, and the shower plate 35 In the film forming apparatus 10 formed so as to eject the film forming gas supplied between the counter electrode 22 and the substrate table 21 from a plurality of gas outlets 36 formed in the shower plate 35. A through hole 50 was formed in the electrode 22.

Since it comprised in this way, since the electromagnetic wave of the alternating voltage applied to the counter electrode 22 can propagate through the through-hole 50, the electric field strength in the formation position of the through-hole 50 can be raised. Therefore, by adjusting the position of the through hole 50, the voltage distribution on the back surface 62 of the counter electrode 22 can be adjusted, so that the electric field strength on the back surface 62 of the counter electrode 22 can be made uniform. As a result, uniform plasma can be generated.
Moreover, since it can implement | achieve only by forming the through-hole 50 in the counter electrode 22, the structure of an apparatus can be simplified.

Further, the opposing electrode 22 is formed in a rectangular shape in plan view, and feeding points 57 to which an AC voltage is applied are provided at positions closer to the four corners than the center point 51 of the opposing electrode 22.
Since it comprised in this way, the voltage distribution of the position close | similar to the four corners in the rectangular opposing electrode 22 can be adjusted, and the electric field strength in the back surface 62 of the opposing electrode 22 can be made uniform. Therefore, uniform plasma can be generated.

Further, the through hole 50 was formed only in the first region 71 including the feeding point 57.
Since it comprised in this way, since the electric field strength in the back surface 62 position corresponding to the feeding point 57 of the counter electrode 22 can be made high reliably, more uniform plasma can be produced | generated.

  Further, a plate member 42 made of a dielectric material was attached to the surface (back surface 62) of the counter electrode 22 facing the shower plate 35, and the through hole 50 of the counter electrode 22 was closed by the plate member 42.

  Since it comprised in this way, since the through-hole 50 formed in the counter electrode 22 with the plate member 42 can be obstruct | occluded, the film-forming gas supplied between the shower plate 35 and the counter electrode 22 is from the through-hole 50. It is possible to reliably supply the gas from the gas outlet 36 toward the substrate table 21 without leaking.

  Then, by adjusting the position of the feed point 57 and the position and size of the through hole 50 as described above, the counter electrode 22 can be adjusted even when a high frequency voltage such as an oscillation frequency of 27.12 MHz is applied. Plasma can be generated uniformly over substantially the entire surface 22. Since the plasma density can be increased by increasing the applied voltage, the individual electron energy (electron temperature) decreases, making it difficult for excessive polymerization reactions to occur, which is one of the causes of photodegradation. This is because the Si—H 2 bond is less likely to be taken into the amorphous silicon film.

  Therefore, even if it is a large substrate of 3 m × 3 m in plan view, it is possible to form a film uniformly on substantially the entire surface of the substrate. From the simulation results, when the through hole was not provided, the film thickness distribution was about ± 30%, but by providing the through hole, the film thickness distribution could be improved to about ± 10%.

  Further, in order to obtain a film quality capable of obtaining a favorable photovoltaic effect of a solar cell by setting the frequency of the applied voltage to 13.56 MHz, the upper limit of the film formation rate is about 500 Å / min. On the other hand, when the frequency of the applied voltage is 27.12 MHz as in the present embodiment, a film capable of obtaining a photovoltaic effect equal to or higher than the above can be formed even when the film formation rate is 1000 Å / min. Therefore, production efficiency can be improved.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. The configuration of the present embodiment is different from that of the first embodiment only in the method of forming the through hole of the counter electrode, and the others are substantially the same configuration. Omitted.
FIG. 8 is a plan view of the counter electrode in the present embodiment.
As shown in FIG. 8, the counter electrode 90 is formed in a rectangular shape larger than the outer shape of the substrate 20 in plan view. A plurality of through holes 91 are formed in the counter electrode 90. The through holes 91 are respectively formed at positions that are point-symmetric with respect to the center point 92 in plan view of the counter electrode 90.

The through hole 91 has a circular shape in plan view. In addition, a high-frequency voltage feeding point 57 from the RF power source 47 is configured at substantially the same position as in the first embodiment. Therefore, the counter electrode 90 is configured to be able to supply power from four locations.
Here, the through hole 91 is formed on substantially the entire surface of the counter electrode 90. In addition, a large number of through holes 91 are formed in the vicinity of the feeding point 57, and the number of through holes 91 is decreased as the center point 92 of the counter electrode 90 is approached. Specifically, as in the first embodiment, the formation of the through hole 91 formed in the first region 71 including the feeding point 57 and the corner of the counter electrode 40 in one of the four divided regions. The density is configured to be higher than the formation density of the through holes 91 formed in the other second regions 72.

  According to this embodiment, the formation density of the through holes 91 in the first region 71 including the feeding point 57 is set higher than the formation density of the through holes 91 outside the first region 71 (second region 72).

  With this configuration, in addition to the effects of the first embodiment, the electric field strength at the back surface position corresponding to the feeding point 57 of the counter electrode 22 can be reliably increased, and the electric field strength at the back surface 62 of the counter electrode 22 can be increased. Since it can be adjusted freely, more uniform plasma can be generated.

It should be noted that the technical scope of the present invention is not limited to the above-described embodiment, and includes those in which various modifications are made to the above-described embodiment without departing from the spirit of the present invention. That is, the specific materials, configurations, and the like given in the embodiment are merely examples, and can be changed as appropriate.
For example, in this embodiment, the case where the dielectric plate is provided on the back surface of the counter electrode has been described. However, the dielectric plate is not provided, and the through hole formed in the counter electrode is filled with the embedded member made of a dielectric. May be. By configuring in this way, substantially the same effect as when the dielectric plate is provided can be obtained.

In the present embodiment, the shape of the through hole is rectangular or circular in plan view, but the through hole may be formed in other shapes.
In the present embodiment, the description has been given of the case where four feeding points are provided on the counter electrode, but the number of feeding points may not be four.
Further, in the present embodiment, various through holes are formed in the counter electrode as a part of the counter electrode, or the through holes are formed with different density depending on the region. You may form a through-hole uniformly.
Furthermore, in this embodiment, although the case where this invention was applied to the film-forming apparatus was demonstrated, you may employ | adopt not only to it but to an etching apparatus.

It is a schematic block diagram of the film-forming apparatus in embodiment of this invention. It is a top view which shows the counter electrode in 1st embodiment of this invention. It is the A section enlarged detail drawing of FIG. It is a top view of the counter electrode used for the simulation in the embodiment of the present invention. It is the B section enlarged detail drawing of FIG. It is a graph which shows a simulation result, (A) is a graph which shows the electric field strength in case the conventional through-hole is not formed, when (A) is the present invention. It is a top view which shows another aspect of the counter electrode in 1st embodiment of this invention. It is a top view which shows the counter electrode in 2nd embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Film-forming apparatus (plasma processing apparatus) 11 ... Vacuum chamber (chamber) 20 ... Substrate 21 ... Substrate table (substrate arrangement electrode) 35 ... Shower plate (plate-like member) 36 ... Gas ejection port 40, 65, 80, 90 ... Counter electrode 42 ... Dielectric plate (plate member) 50, 67, 81, 91 ... Through hole 57 ... Feeding point

Claims (8)

A substrate placement electrode on which a substrate to be treated can be placed;
A counter electrode made of a conductive material that is arranged to oppose the substrate arrangement electrode substantially in parallel and is configured to be able to apply an AC voltage to the opposite side of the substrate arrangement electrode;
A plate-like member made of a dielectric material, disposed between the counter electrode and the substrate placement electrode,
The plate-like member jets the processing gas supplied between the plate-like member and the counter electrode from a plurality of gas jets formed in the plate-like member toward the substrate arrangement electrode. In the plasma processing apparatus formed in
A plasma processing apparatus, wherein a through hole is formed in the counter electrode. The counter electrode is formed in a rectangular shape in plan view,
2. The plasma processing apparatus according to claim 1, wherein feed points to which the AC voltage is applied are provided at positions closer to the four corners than a center point of the counter electrode. 3.   The plasma processing apparatus according to claim 2, wherein the through hole is formed only in a predetermined region including the feeding point.   The plasma processing apparatus according to claim 2, wherein a formation density of the through holes in a predetermined region including the feeding point is higher than a formation density of the through holes outside the predetermined region.   The plasma processing apparatus according to claim 1, wherein the through hole is formed only in a predetermined region including a corner portion of the counter electrode.   3. The plasma according to claim 1, wherein a formation density of the through holes in a predetermined region including a corner portion of the counter electrode is higher than a formation density of the through holes outside the predetermined region. Processing equipment. A plate member made of a dielectric material is attached to a surface of the counter electrode facing the plate-like member,
The plasma processing apparatus according to claim 1, wherein the through hole of the counter electrode is closed by the plate member.   The plasma processing apparatus according to claim 1, wherein the through hole of the counter electrode is closed by an embedded member made of a dielectric.

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