JP5212275B2 - Electrode plate for plasma processing equipment - Google Patents

Description

  The present invention relates to an electrode plate for a plasma processing apparatus that discharges a plasma generating gas while passing it in the thickness direction in the plasma processing apparatus.

  In a plasma processing apparatus such as a plasma etching apparatus or a plasma CVD apparatus used in a semiconductor device manufacturing process, an upper electrode and a lower electrode connected to a high-frequency power source are disposed in a chamber so as to face each other, for example, vertically. The substrate to be processed is placed in a state where a plasma is generated by applying a high frequency voltage while flowing a gas from the through hole formed in the upper electrode toward the substrate to be processed, and the substrate to be processed is subjected to processing such as etching. It is configured to do. The electrode plate used in this plasma processing apparatus is formed in a disk shape having an outer diameter of about 400 mm by, for example, single crystal silicon, and a large number of gas passage holes having an inner diameter of about 0.5 mm are penetrated through the entire surface at a pitch of about 8 mm. Formed.

A cooling plate made of a metal such as aluminum is provided on the back surface of the electrode plate.
For example, in Patent Document 1, a cooling plate made of a metal such as aluminum whose surface is anodized is provided on the back surface of the electrode plate, and in Patent Document 2, a metal film is provided on the back surface of the electrode plate. The cooling plate is fastened and fixed.

JP 2003-332314 A Japanese Patent Laid-Open No. 11-256370

By the way, in the plasma processing apparatus configured as described above, the diameter of the wafer is increased from 200 mm to 300 mm, and strict process control that does not allow dimensional variations of several nanometers has been required. High in-plane uniformity has become indispensable for plasma processing such as etching.
In order to realize this requirement, it is desirable to keep the temperature of the outer peripheral portion and the central portion of the electrode plate constant during the plasma treatment, but at present, the outer peripheral portion of the electrode plate tends to radiate heat to the periphery. The central part is difficult to dissipate heat, and a temperature difference is generated between the central part and the outer peripheral part, which is an obstacle to ensuring in-plane uniformity of plasma processing.

  The present invention has been made in view of such circumstances, and it is for a plasma processing apparatus capable of reducing the temperature difference generated between the central portion and the outer peripheral portion of the electrode plate and improving the in-plane uniformity of the plasma processing. An object is to provide an electrode plate.

The electrode plate of the present invention is formed such that a plurality of gas passage holes penetrating in the thickness direction are formed, and groove-like or spot-like concave portions are dispersed in the surface direction of the back surface portion avoiding these gas passage holes. The volume occupied by the recess per unit volume of the electrode plate is larger in the outer peripheral portion than in the central portion of the electrode plate.
The electrode plate of the present invention is formed by laminating a plurality of electrode component plates and a plurality of gas passage holes penetrating these electrode component plates in the thickness direction. In addition, groove-shaped or spot-shaped hollow portions are formed so as to be dispersed in the surface direction while avoiding the gas passage holes, and the occupied volume of the hollow portions per unit volume of the electrode plate is larger than that of the central portion of the electrode plate. Thus, the outer peripheral portion is formed larger.

In the electrode plate of the present invention, the recessed portion or the hollow portion is formed, so that the portion becomes a heat insulating space. And since it is provided so that a recessed part or a hollow part may be disperse | distributed to a surface direction as the whole electrode plate, a heat insulation space will disperse | distribute to a surface direction. In this case, the volume occupied by the concave portion or the hollow portion per unit area of the electrode plate is formed larger in the outer peripheral portion than in the central portion of the electrode plate, so that the outer peripheral portion of the electrode plate is more than the central portion. The heat insulation effect is great for heat transfer in the thickness direction, which suppresses heat transfer in the thickness direction of the outer periphery of the electrode plate that easily dissipates heat to the periphery, and as a whole electrode plate, the outer periphery and the center And the temperature difference can be reduced.
As a means for forming the occupied volume of the concave portion per unit volume of the electrode plate larger in the outer peripheral portion than in the central portion of the electrode plate, the transverse area of the concave portion or the hollow portion is set in the outer peripheral portion compared with the central portion of the electrode plate. When the recess or hollow part is uniform as the cross-sectional area, the arrangement interval is made smaller at the outer peripheral part than the center part, or these cross-sectional area and arrangement interval It is possible to apply means such as combining the above.

The electrode plate of the present invention is formed such that a plurality of gas passage holes penetrating in the thickness direction are formed, and groove-like or spot-like concave portions are dispersed in the surface direction of the back surface portion avoiding these gas passage holes. The volume occupied by the concave portion per unit volume of the electrode plate is smaller in the outer peripheral portion than in the central portion of the electrode plate, and a heat conductive material is provided in the concave portion.
The electrode plate of the present invention is formed by laminating a plurality of electrode component plates and a plurality of gas passage holes penetrating these electrode component plates in the thickness direction. In addition, groove-shaped or spot-shaped hollow portions are formed so as to be dispersed in the surface direction while avoiding the gas passage holes, and the occupied volume of the hollow portions per unit volume of the electrode plate is larger than that of the central portion of the electrode plate. The outer peripheral part is formed smaller, and a heat conductive material is provided in the hollow part.

  In this case, contrary to the previous invention, this can be controlled along the surface direction while enhancing the heat dissipation of the electrode plate by the heat conducting material provided in the recess or the hollow part. That is, the occupied volume by the heat conductive material is formed smaller in the outer peripheral portion than in the central portion of the electrode plate, so that the central portion easily dissipates heat in the thickness direction of the electrode plate, whereas the outer peripheral portion is thicker. It is difficult to dissipate heat in the vertical direction. Thereby, uniform heat dissipation is performed as a whole. Therefore, the heat generated on the plasma discharge surface is quickly transmitted to the back side via this heat conducting material and dissipated to the cooling plate. As a result, the temperature difference between the outer peripheral portion and the central portion can be reduced as the entire electrode plate.

  According to the electrode plate of the present invention, the concave portion formed on the back surface or the hollow portion formed inside is dispersed in the surface direction, and the occupied volume per unit volume is different between the central portion and the outer peripheral portion of the electrode plate. Thus, the heat transferability is controlled between the central portion and the outer peripheral portion of the electrode plate, the temperature difference between the central portion and the outer peripheral portion can be reduced, and the in-plane uniform plasma treatment can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS (a) which shows 1st Embodiment of the electrode plate of this invention is a rear view, (b) is a longitudinal cross-sectional view. It is a schematic block diagram which shows the example of the plasma processing apparatus in which the electrode plate of FIG. 1 is used. (A) which shows 2nd Embodiment of the electrode plate of this invention is a rear view, (b) is a longitudinal cross-sectional view. It is a longitudinal cross-sectional view which shows 3rd Embodiment of the electrode plate of this invention. It is a longitudinal cross-sectional view which shows 4th Embodiment of the electrode plate of this invention. It is a longitudinal cross-sectional view which shows 5th Embodiment of the electrode plate of this invention.

Hereinafter, embodiments of the electrode plate of the present invention will be described with reference to the drawings.
First, a plasma etching apparatus will be described as a plasma processing apparatus using this electrode plate.
As shown in the schematic cross-sectional view of FIG. 2, the plasma etching apparatus 1 is provided with an electrode plate (upper electrode) 3 in the upper part of the vacuum chamber 2 and a pedestal (lower electrode) 4 that can be moved up and down in the lower part. Are provided in parallel with the electrode plate 3 at a distance from each other. In this case, the upper electrode plate 3 is supported in an insulated state by the insulator 5 with respect to the wall of the vacuum chamber 2, and the electrostatic chuck 6 and the silicon-made surrounding material are placed on the mount 4. A support ring 7 is provided, and a wafer (substrate to be processed) 8 is placed on the electrostatic chuck 6 with the peripheral edge supported by the support ring 7. Further, an etching gas supply pipe 9 is provided in the upper part of the vacuum chamber 2, and the etching gas sent from the etching gas supply pipe 9 passes through the diffusion member 10 and then is a gas passage hole provided in the electrode plate 3. 11 is made to flow toward the wafer 8 and discharged from the discharge port 12 on the side of the vacuum chamber 2 to the outside. On the other hand, a high frequency voltage is applied between the electrode plate 3 and the gantry 4 by a high frequency power source 13.

  The electrode plate 3 is formed in a disk shape with silicon, and a cooling plate 14 made of aluminum or the like having excellent thermal conductivity is fixed to the back surface of the electrode plate 3, and the gas of the electrode plate 3 is also fixed to the cooling plate 14. Through holes 15 are formed at the same pitch as the gas passage holes 11 so as to communicate with the passage holes 11. The structure of the electrode plate 3 will be described later.

In this plasma etching apparatus 1, when an etching gas is supplied by applying a high-frequency voltage from a high-frequency power source 13, the etching gas passes through the diffusion member 10 and passes through the gas passage hole 11 provided in the electrode plate 3 to form an electrode. It is released into the space between the plate 3 and the gantry 4 and becomes plasma in this space, hits the wafer 8, and the surface of the wafer 8 is etched by sputtering, that is, physical reaction and chemical reaction of the etching gas. Is done.
Further, for the purpose of uniformly etching the wafer 8, the generated plasma is concentrated on the central portion of the wafer 8, and is prevented from diffusing to the outer peripheral portion, thereby generating a uniform plasma between the electrode plate 3 and the wafer 8. In order to generate the plasma, the plasma generation region 16 is usually surrounded by a silicon shield ring 17.

Next, the detailed structure of the electrode plate 3 will be described with reference to FIG.
The electrode plate 3 is formed in a disc shape from single crystal silicon, columnar crystal silicon, or polycrystalline silicon, and a large number of gas passage holes 11 are provided side by side on a plurality of concentric circles having different diameters.
In addition, the electrode plate 3 has a plurality of concentric ring groove-shaped recesses 21 </ b> A to 21 </ b> F formed on the back surface portion joined to the cooling plate 14. These recesses 21A to 21F are arranged one by one between the pitch circles p1 to p7 formed by the gas passage holes 11, and are all formed to the same depth as shown in FIG. However, the concave portion 21A arranged at the outermost peripheral portion is formed with the widest width, and a plurality of concave portions 21B to 21E are formed so that the width gradually decreases from the concave portion 21A at the outermost peripheral portion inward in the radial direction. The width of the recessed portion 21F that is disposed and is disposed in the vicinity of the central portion on the innermost peripheral side is formed to be the smallest.

  The electrode plate 3 is fixed in the plasma processing apparatus 1 by screwing or the like with its back surface in contact with the cooling plate 14. In this fixed state, the recesses 21 </ b> A to 21 </ b> F on the back surface are covered with the cooling plate 14 to form a ring-shaped cavity. Therefore, between the electrode plate 3 and the cooling plate 14, a plurality of ring-shaped cavities with gradually decreasing cross-sectional areas are formed from the outer peripheral portion of the electrode plate 3 toward the central portion.

By performing plasma treatment using this electrode plate 3, the space formed by the recesses 21A to 21F on the back surface becomes a heat insulating space, and the heat conducted inside the electrode plate 3 flows in the thickness direction at the portions of the recesses 21A to 21F. Heat transfer is cut off, and heat radiation is suppressed accordingly. And since the cross-sectional area of this recessed part 21A-21F becomes small gradually as it goes to the center part from the outer peripheral part of the electrode plate 3, the heat insulation effect by recessed part 21A-21F is large in an outer peripheral part, and becomes small in a center part. .
Therefore, this electrode plate 3 is in a state in which heat transfer in the thickness direction is less likely to proceed in the outer peripheral portion than in the central portion, and the outer peripheral portion is originally in a state in which heat is easily radiated to the periphery such as radially outward. Thus, as a sum of these, the entire electrode plate 3 is radiated heat evenly in the plane. Thereby, the temperature difference between the central portion and the outer peripheral portion of the electrode plate 3 is reduced, the temperature is made uniform in the surface, and the in-plane uniformity of the plasma processing, for example, the in-plane uniformity of the etching depth is improved. Can do.

FIG. 3 shows a second embodiment of the electrode plate of the present invention.
The electrode plate 25 of this embodiment is also provided with a plurality of concentric ring groove-like recesses 26A to 26F (one each between the pitch circles p1 to p7 of the gas passage hole 11) on the back surface in contact with the cooling plate 14. This is the same as in the case of the electrode plate 3 of the first embodiment. In the electrode plate 3 of the first embodiment, the depth of each of the recesses 21A to 21F is constant, and the width is changed from the outer peripheral portion of the electrode plate 3 toward the central portion. However, the electrode plate of the second embodiment 2B, the width of each of the recesses 26A to 26F on the back surface thereof is constant, and the depth is gradually shallower from the outer periphery to the center of the electrode plate 25, as shown in FIG. Yes.
Accordingly, the cross-sectional areas of the recesses 26A to 26F are gradually decreased from the outer peripheral portion of the electrode plate 25 toward the central portion, similar to that of the first embodiment, and with the electrode plate 3 of the first embodiment. Similarly, the temperature difference between the central portion and the outer peripheral portion of the electrode plate 25 can be reduced, the temperature can be made uniform in the surface, and the in-plane uniformity of the plasma treatment can be improved.

FIG. 4 shows a third embodiment of the electrode plate of the present invention.
The electrode plate 31 of this embodiment has a configuration in which two electrode component plates 32 are laminated, and a plurality of ring-shaped hollow portions 33A to 33F are concentrically disposed between these laminated surfaces (pitch of the gas passage holes 11). Are formed between the circles p1 to p7). These hollow portions 33 are formed by abutting concave grooves formed in the same shape on the laminated surface of each electrode component plate 32. Moreover, although the dimension along the thickness direction of the electrode plate 31 is set to be the same for each of the hollow portions 33A to 33F, the width along the surface direction of the electrode plate 31 is from the outer peripheral portion of the electrode plate 31 to the central portion. It is set so as to gradually become smaller.
Therefore, this electrode plate 31 is formed so that the cross-sectional area of each of the hollow portions 33A to 33F gradually decreases from the outer peripheral portion of the electrode plate 31 toward the center portion, and the same effect as the electrode plate of each of the above embodiments is obtained. can get.

FIG. 5 shows a fourth embodiment of the electrode plate of the present invention.
The electrode plate 35 of this embodiment has a configuration in which two electrode component plates 36 are stacked in the same manner as in the third embodiment, and ring-shaped hollow portions 37A to 37F formed between these stacked surfaces are provided. The width dimension along the surface direction of the electrode plate 35 is set to be the same, and the dimension along the thickness direction is set to gradually decrease from the outer peripheral portion of the electrode plate 35 toward the central portion.
Also in this electrode plate 35, the cross-sectional areas of the hollow portions 37A to 37F are gradually reduced from the outer peripheral portion to the center portion of the electrode plate 35, and the same effect as that of the above embodiment can be obtained.

In each of the above embodiments, the thickness of the electrode plate is formed by forming a heat insulating space by a concave portion or a hollow portion in the electrode plate and changing the cross-sectional area of the heat insulating space from the outer peripheral portion of the electrode plate toward the central portion. The heat radiation characteristics of the direction are controlled to make it uniform in the surface, but by disposing a heat conductive material having better heat conductivity than silicon, which is a constituent material, on the electrode plate. The heat dissipation characteristics of the electrode plate may be controlled.
The fifth embodiment shown in FIG. 6 shows an electrode plate provided with such a heat conductive material. The electrode plate 41 has a plurality of concentric ring groove-like recesses 42A to 42F (one each between the pitch circles p1 to p7 of the gas passage hole 11) formed on the back surface thereof, and these recesses 42A to 42F. The cross sectional area of the electrode plate 41 is formed so as to gradually increase from the outer peripheral portion toward the central portion of the electrode plate 41, and the heat conducting material 43 is tightly fitted in the concave portions 42A to 42F. It is arranged.
In the electrode plate 41, the heat transmitted in the thickness direction is quickly moved in the portion of the heat conductive material 43 and transmitted to the cooling plate 14 on the back surface. In that case, since the cross-sectional area of the heat conducting material 43 gradually increases from the outer peripheral portion of the electrode plate 41 toward the central portion, the central portion is more difficult to dissipate than the outer peripheral portion that easily dissipates heat to the periphery. However, the thermal conductivity increases in the thickness direction, and as a result, the entire surface has uniform heat dissipation characteristics, and the temperature distribution on the discharge surface is uniform in the surface.

When the heat conductive material 43 is arranged on the electrode plate 41 in this way, the in-plane uniformity of the temperature distribution is achieved by gradually increasing the cross-sectional area from the outer peripheral portion of the electrode plate 41 toward the central portion. Can do. In this case, in the fifth embodiment, the recesses 42A to 42F are illustrated with the same depth and the same width as the first embodiment, but the width is the same as in the second embodiment. The depth may be changed (by gradually increasing the depth from the outer periphery to the center of the electrode plate), or it may be formed between the two electrode component plates as in the third or fourth embodiment. You may arrange | position a heat conductive material in a hollow part.
As the heat conductive material, for example, aluminum or the like can be applied as a metal having better heat conductivity than silicon constituting the main body of the electrode plate. In addition, a conductive adhesive can also be applied. As the conductive adhesive, a conductive filler such as silver, aluminum, nickel, or carbon is used as an adhesive such as silver, copper, aluminum, or indium, or an epoxy resin. A mixed conductive adhesive or the like can be used.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in each of the embodiments described above, the gas passage holes are arranged concentrically so that the recesses or hollow portions are formed in a ring shape so as to be arranged between the pitch circles. The concave portions or the hollow portions may be formed in a lattice shape in a plan view passing between these gas through holes. Moreover, you may disperse | distribute these recessed parts or hollow parts in the spot form not in groove shape but in the position which avoided the gas passage hole.

  In addition, the cross-sectional area of these concave portions or hollow portions was changed from the outer peripheral portion of the electrode plate toward the central portion, but the cross-sectional area was not changed, for example, the outer peripheral portion of the electrode plate was arranged at a narrow interval, and the central portion Then, the arrangement interval may be changed, for example, the arrangement interval may be wide. Moreover, you may make it differ combining both a cross-sectional area and arrangement | positioning space | interval. In short, the occupied volume of the recess or hollow part per unit volume of the electrode plate may be changed between the central part and the outer peripheral part of the electrode plate, and when the heat insulating effect in the thickness direction of the outer peripheral part is made larger than the central part, The occupied volume of the concave portion or the hollow portion per unit volume may be formed larger in the outer peripheral portion than in the central portion of the electrode plate. When the heat dissipation in the thickness direction is promoted, the occupied volume of the concave portion or the hollow portion per unit volume may be formed larger in the central portion than in the outer peripheral portion of the electrode plate.

  Furthermore, when a plurality of electrode configuration plates are stacked to form an electrode plate as in the third embodiment and the fourth embodiment, a configuration in which three or more electrode configuration plates are stacked may be employed. Further, among these multiple electrode component plates, a bent gas passage hole may be formed by inclining the through hole of the lower electrode component plate forming the discharge surface with respect to the thickness direction, This is effective in preventing the plasma from wrapping around the back side.

DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 2 Vacuum chamber 3 Electrode plate 11 Gas passage hole 13 High frequency power supply 14 Cooling plate 15 Through-hole 21A-21F Recess 25 Electrode plate 26A-26F Recess 31 Electrode plate 32 Electrode component plate 33A-33F Hollow part 35 Electrode plate 36 Electrode component plates 37A to 37F Hollow portion 41 Electrode plates 42A to 42F Recess 43 Heat conduction material p1 to p7 Pitch circle

Claims (4)

  A plurality of gas passage holes penetrating in the thickness direction are formed, and groove-like or spot-like concave portions are formed so as to be dispersed in the surface direction of the back surface while avoiding these gas passage holes. The electrode plate for a plasma processing apparatus is characterized in that the occupied volume of the recess is larger in the outer peripheral portion than in the central portion of the electrode plate.   A plurality of electrode component plates are laminated, and a plurality of gas passage holes penetrating these electrode component plates in the thickness direction are formed. Avoid the gas passage holes between the lamination surfaces of these electrode component plates. Groove-shaped or spot-shaped hollow portions are formed so as to be dispersed in the surface direction, and the occupied volume of the hollow portion per unit volume of the electrode plate is formed larger in the outer peripheral portion than in the central portion of the electrode plate. An electrode plate for a plasma processing apparatus.   A plurality of gas passage holes penetrating in the thickness direction are formed, and groove-like or spot-like concave portions are formed so as to be dispersed in the surface direction of the back surface while avoiding these gas passage holes. The electrode plate for a plasma processing apparatus is characterized in that the volume occupied by the recess is smaller in the outer peripheral portion than in the central portion of the electrode plate, and a heat conductive material is provided in the recess.   A plurality of electrode component plates are laminated, and a plurality of gas passage holes penetrating these electrode component plates in the thickness direction are formed. Avoid the gas passage holes between the lamination surfaces of these electrode component plates. Groove-shaped or spot-shaped hollow portions are formed so as to be dispersed in the surface direction, and the occupied volume of the hollow portion per unit volume of the electrode plate is smaller in the outer peripheral portion than in the central portion of the electrode plate. An electrode plate for a plasma processing apparatus, wherein a heat conductive material is provided in the hollow portion.

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