JP2011003730A - Silicon ring for plasma treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon ring which can be inexpensively manufactured as a silicon ring such as a support ring, a focus ring and a shield ring in a plasma treatment apparatus and reduces loss in materials and can be easily handled and hardly causes impurities.SOLUTION: The silicon ring has a structure in which a plurality of arc members 21 are arranged in a circumferential direction and fixed like a ring, recesses 25, 28 formed by cutting a part of a range of a plate thickness of each of the arc members 21 along a plasma opposing surface 31 and a convex portions 24, 27 engaged with the recesses 25, 28 are formed between ends of both the adjacent arc members 21, and an adhesive for fixing each of the arc members 21 is provided between engaging surfaces of the recesses and convex portions so as to avoid abutting surfaces 34 between the arc members 21 exposed on the plasma opposing surface 31.

Description

  The present invention relates to a silicon ring such as a support ring for mounting a substrate to be processed in a plasma processing apparatus, a focus ring provided on the outside of the substrate to be processed, and a shield ring for supporting an upper electrode.

  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.

  In this type of plasma processing apparatus, a substrate to be processed is placed on a support ring. For example, as described in Patent Document 1, this support ring is formed in a ring shape on the outer peripheral portion of the lower electrode, and the outer peripheral portion of the substrate to be processed is placed on a concave support step formed on the inner peripheral portion thereof. It is supposed to be. Further, a focus ring is provided separately from the support ring or integrally with the support ring. As described in Patent Document 2, for example, the focus ring is disposed so as to surround the periphery of the substrate to be processed in order to make the plasma processing at the peripheral edge of the substrate to be processed uniform. Further, a shield ring for electromagnetic shielding is also provided around the upper electrode, and is fixed to the chamber wall by a quartz ring (insulator).

These support ring, focus ring, and shield ring are made of silicon and are formed in a ring shape having a larger diameter than the substrate to be processed and the electrode.
These support ring, focus ring, and shield ring are generally sliced ingots such as single crystal silicon and columnar crystal silicon, and most of the center of this sliced disk is deleted except for its peripheral edge. However, in the invention described in Patent Document 2, a plurality of arc-shaped divided pieces are arranged in a ring shape.

JP 2002-50672 A JP 2008-251639 A

However, in the method of forming a large-diameter disk sliced from an ingot in a ring shape, the material loss is large and the cost is high. In particular, in recent years, the substrate to be processed has become larger in diameter, and accordingly, each silicon ring needs to have a larger diameter, resulting in an increase in material loss and an increase in cost.
Further, a large-diameter ring-shaped part is liable to be broken or the like depending on how it is supported, and the handleability is poor.
In the case of a method in which a ring is divided into a plurality of pieces and the arc-shaped members (divided pieces) are connected in the circumferential direction and assembled into a ring shape as in the case of the one described in Patent Document 2, material loss can be reduced. There is a risk that impurities due to the adhesive may be released to the plasma generation region from between the joining surfaces of the arc-shaped members.

  The present invention has been made in view of such circumstances, and silicon rings such as a support ring, a focus ring, and a shield ring in a plasma processing apparatus can be manufactured at low cost with reduced material loss, and An object of the present invention is to provide a silicon ring that is easy to handle and generates less impurities.

  The silicon ring of the present invention is a silicon ring in which one of the front and back surfaces is a plasma facing surface directed toward the plasma generation region, and a plurality of arc-shaped members are arranged in the circumferential direction and fixed in a ring shape, A concave portion formed by cutting a part of the thickness range of each arc-shaped member along the plasma facing surface and a convex portion that engages with the concave portion are formed between the end portions of both adjacent arc-shaped members. In addition, an adhesive for fixing each arcuate member is provided between the engagement surfaces of the recesses and the projections so as to avoid between the butting surfaces of the arcuate members exposed on the plasma facing surface. And

By adopting a configuration composed of a plurality of arc-shaped members, material loss can be greatly reduced as compared to cutting out from a disk into a ring shape. In this case, since the arc-shaped members are aligned and fixed in the circumferential direction, the abutting portions of the arc-shaped members are disposed on the plasma facing surface (consumable surface), and plasma is generated between the abutting surfaces. May enter. For this reason, if an adhesive is provided between the butted surfaces, impurities may be released into the plasma region, but the adhesive is provided at a position that avoids the space between the butted surfaces exposed on the plasma facing surface. Therefore, even if plasma enters between the butt surfaces, it does not reach the adhesive.
In the silicon ring thus fixed, the adhesive interposed between the arcuate members functions as a cushioning material to relieve stress, thus preventing the occurrence of breakage during handling. can do.

Further, the silicon ring of the present invention is a silicon ring in which one of the front and back surfaces is a plasma facing surface directed toward the plasma generation region, and a ring array structure in which a plurality of arc-shaped members are arranged in the circumferential direction has a plate thickness. A plurality of layers are stacked in the direction, and the butting surfaces between the respective arc-shaped members are arranged in a state shifted in the circumferential direction between the upper and lower adjacent ring row structural bodies, and between the stacked surfaces of these ring row structural bodies, The adhesive for fixing the arc-shaped members may be provided so as to avoid the space between the butted surfaces of the arc-shaped members exposed on the plasma facing surface.
What is necessary is just to set arbitrarily the number of lamination | stacking steps | paragraphs of 2 steps | paragraphs or more.

  According to the silicon ring for a plasma processing apparatus of the present invention, the configuration in which a plurality of arc-shaped members are connected to each other can significantly reduce material loss compared to cutting out from a disk into a ring shape. It is possible to suppress an increase in cost when the diameter is increased. Moreover, since the adhesive agent intervening on the fixed surface functions as a cushioning material and can relieve stress, it can be prevented from being damaged during handling. Moreover, since the adhesive is provided at a position that avoids the space between the butted surfaces of each arcuate member exposed on the plasma facing surface, even if the plasma enters between the butted surfaces, it can reach the adhesive. Rather, impurities can be prevented from entering the plasma region, and high-quality plasma treatment can be performed.

It is a perspective view which shows the silicon ring of 1st Embodiment of this invention. It is a perspective view of the 1st member which comprises some silicon rings of FIG. It is a perspective view of the 2nd member which comprises some silicon rings of FIG. It is a longitudinal cross-sectional view in alignment with the circumferential direction of a part of FIG. It is a schematic sectional drawing which shows the example of the plasma processing apparatus using the silicon ring of this invention. It is a perspective view which shows the silicon ring of 2nd Embodiment of this invention. It is a perspective view of the circular-arc-shaped member which comprises the silicon ring of FIG. It is a longitudinal cross-sectional view in alignment with the circumferential direction of a part of FIG.

Hereinafter, embodiments of the silicon ring 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 silicon ring.
As shown in the schematic cross-sectional view of FIG. 5, this plasma etching apparatus 1 is provided with an electrode plate (upper electrode) 3 in the upper part of the vacuum chamber 2 and a gantry (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 passes through the through holes 11 provided in the electrode plate 3. Through the discharge port 12 on the side of the vacuum chamber 2 and discharged 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.

  In addition, 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. The cooling plate 14 also penetrates the electrode plate 3. Through holes 15 are formed at the same pitch as the through holes 11 so as to communicate with the holes 11.

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, passes through the through-hole 11 provided in the electrode plate 3, and the electrode plate. 3 is released into the space between the gantry 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, ie, physical reaction, and chemical reaction of the etching gas. The
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, as a first embodiment of the silicon ring of the present invention, the detailed structure of the support ring 7 described above will be described.
The support ring 7 has, for example, an inner diameter of 450 mm, an outer diameter of 550 mm, and a thickness of 6 to 8 mm, and connects a plurality of arc-shaped members 21 as shown in FIGS. Configured. These arc-shaped members 21 are composed of a first member 21A having a protruding portion 22 facing upward and a second member 21B having a protruding portion 23 facing downward. As shown in FIG. 2, the first member 21 </ b> A has an upward protruding portion 22 integrally formed at the middle portion in the longitudinal direction of the flat plate portion 24 having an arc-shaped belt shape, thereby Concave portions 25 with the upper side open are disposed on both sides of the protruding portion 22, and a step portion 26 slightly lower than the upper surface of the protruding portion 22 is provided along the circumferential direction on the inner peripheral portion of the protruding portion 22. Is formed. As shown in FIG. 3, the second member 21 </ b> B is opposite to the first member 21 </ b> A, and a protrusion 23 directed downward is integrally formed in an intermediate portion in the length direction of the flat plate portion 27 having an arc-shaped belt shape. By forming the concave portions 28 on both sides of the downward projection 23, the concave portions 28 opened downward are arranged, and the inner peripheral portion of the flat plate portion 27 is slightly lower than the upper surface of the flat plate portion 27. The part 29 is formed along the circumferential direction. In any member, the protrusions 22 and 23 are formed to have a length that is approximately 1/3 of the circumferential length of the arc-shaped members 21A and 21B, and the ends of the flat plate portions 24 and 27 on both sides thereof are also circumferentially long. The length is approximately 1/3 of the length.

  The first member 21A and the second member 21B are alternately arranged along the circumferential direction, so that the protrusions of the second member 21B are formed in the recesses 25 arranged on both sides of the protrusions 22 of the first member 21A. End portions (convex portions) of the flat plate portion 27 disposed on both sides of the plate 23 are engaged, and the flat plate portions 24 and 27 of both the members 21A and 21B are coupled to each other. Therefore, the upper surface of the projection 22 of the first member 21A and the upper surface of the flat plate portion 27 of the second member 21B are alternately arranged on the upper surface of the entire support ring 7, and the flat plate portion 24 of the first member 21A is arranged on the lower surface. The lower surface and the lower surface of the protrusion 23 of the second member 21B are alternately arranged. Further, both end surfaces in the circumferential direction of the protrusions 22 in the first member 21A and the end surfaces in the circumferential direction of the flat plate portions 27 of the two second members 21B adjacent to each other are abutted, and these are abutted to each other. The upper surface of the protruding portion 22 of the first member 21A and the upper surface of the flat plate portion 27 of the second member 21B are formed flush with each other as a plasma facing surface 31 that faces the plasma generation region 16 during plasma processing. Moreover, in the state combined in this ring shape, the step part 26 of the projection part 22 of the first member 21A and the step part 29 of the flat plate part 27 of the second member 21B are annularly connected to the inner peripheral part of the upper surface. A support step 32 for mounting the peripheral edge of the wafer 8 is formed.

In this case, each arcuate member 21 (21A, 21B) is fixed by a conductive adhesive 33 such as a metal braze or a conductive resin adhesive, but is a flat plate of the first member 21A parallel to the plasma facing surface 31. The adhesive 33 is interposed in a specific region between the overlapping surfaces of the upper surface of the portion 24 and the lower surface of the flat plate portion 27 of the second member 21B. Specifically, as shown in FIG. 4, the position of the flat plate portion 24 of the first member 21A is slightly shifted from the abutment surface 34 of the projection portion 22 of the first member 21A and the flat plate portion 27 of the second member 21B. A region up to the vicinity of the end surface is a fixing region 35. Therefore, the fixing region 35 is orthogonal to the abutting surface 34 of each arcuate member 21A, and extends in parallel with the plasma facing surface 31 at a position separated from the abutting surface 34 by, for example, about 0.2 to 0.5 mm. Thus, the adhesive 33 does not enter the abutting surface 34. In the example shown in FIG. 4, a slight gap is formed between the end surface of the flat plate portion 24 of the first member 21A and the end surface of the protruding portion 23 of the second member 21B. This is because the butted surfaces 34 of the surface 31 are in close contact with no gap.
As the adhesive 33, a conductive adhesive in which a conductive filler such as silver, aluminum, nickel, or carbon is mixed with an adhesive such as a metal brazing material such as silver, copper, aluminum, or indium or an epoxy resin, or the like is used.

The support ring 7 thus configured is fixed on the gantry 4 of FIG. 5 with the plasma facing surface 31 facing upward, and the peripheral portion of the wafer 8 is placed on the support step 32 of the inner peripheral portion thereof. Is done. In this case, the above-described support ring having an inner diameter of 450 mm, an outer diameter of 550 mm, and a thickness of 6 to 8 mm has a weight exceeding 1 kg, but the adhesive 33 is interposed between the connected arc-shaped members 21. Therefore, the adhesive 33 functions as a cushioning material, and the stress generated during the fixing operation to the plasma processing apparatus 1 is relaxed, and the occurrence of breakage is effectively prevented.
During the plasma processing, the plasma collides with the plasma facing surface 31. In this case, the end surfaces of the respective arcuate members 21 are closely abutted on the plasma facing surface 31 as described above. The plasma is prevented from entering between the abutting surfaces 34. Even if the plasma enters between the abutting surfaces 34, the adhesive 33 is not interposed between the abutting surfaces 34. Therefore, the plasma does not contact the adhesive 33, and the plasma generation region 16 is the adhesive. 33 is not contaminated. Therefore, plasma processing can be performed with high quality.

6 to 8 show a second embodiment of the silicon ring of the present invention. In these drawings, portions common to the first embodiment are denoted by the same reference numerals and description thereof is simplified.
The silicon ring of the second embodiment is also a support ring. The support ring 41 has a configuration in which arc-shaped members 42 are stacked in two upper and lower stages, and the arc-shaped member 42 forms ring row constituting bodies 43 and 44 for each stage, and the upper ring row constituting body The upper surface of 43 is a plasma facing surface 31.
As shown in FIG. 7, the upper ring array structure 43 includes a plurality of arc-shaped members 42 </ b> A each having a step 44 on the inner periphery, and the step 44 is connected to the inner periphery. A support step 45 for mounting the peripheral portion of the wafer 8 is formed on the lower ring array structure 44, and the lower ring row structure 44 has a plurality of arc-shaped members 42B having a uniform thickness arranged in the circumferential direction. It is the structure which was made. A specific region of the laminated surface of both the ring array members 43 and 44 is a fixing region 35. In this case, the upper ring row structure 43 and the lower ring row structure 44 are arranged in a state where the butting surfaces 34 of the respective arc-shaped members 42 are shifted in the circumferential direction, and the adhesive 33 in the fixing region 35 is Similar to the support ring 7 of the first embodiment, the upper ring array structure 43 exposed to the plasma facing surface 31 is provided with a slight distance from each butting surface 34.

The support ring 41 of the second embodiment is one in which each arc-shaped member 42 is constructed and integrated in a so-called brickwork state, and this support ring 41 is the same as the support ring 7 of the first embodiment. Since the adhesive 33 is not interposed between the butted surfaces 34 of the arc-shaped member 42 exposed on the plasma facing surface 31, the generation of impurities can be effectively prevented.
When the support ring 41 is assembled, the arc-shaped members 42A are arranged in a ring shape with respect to the ring row structure 43 of one stage, and the adhesive 33 is applied thereon, and the other ring row structure is formed. 44 arcuate members 42B may be fixed while being arranged. For example, the arc-shaped members 42A of the upper ring array structure 43 are arranged in an inverted state while being arranged in an intimate contact state and assembled into a ring shape, and the adhesive is avoided by avoiding the butting surfaces 34 of the arc-shaped members 42A thereon. 33 may be applied, and the arc-shaped members 42B of the other ring array structure 44 may be aligned and fixed.

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, the fixing region of each arc-shaped member does not necessarily have to be a plane parallel to the plasma facing surface, may be a surface slightly inclined with respect to the plasma facing surface, or a surface having serrated irregularities. And may be formed along the plasma facing surface as a whole.
In the first embodiment, the circumferential length between the projection and the flat plate of each arcuate member is 1/3, but the dimensional relationship may be arbitrarily set. In addition, as in the support ring of the first embodiment, when a concave portion and a convex portion (an end portion of the flat plate portion) are arranged on the arc-shaped member and engaged with each other, the arc-shaped member is arc-shaped in the first embodiment. By cutting off one side (upper surface) of the front and back surfaces of the member, leaving the protruding portion, the cut-off portion is made a concave portion. In the adjacent arc-shaped member, a concave portion is formed on the opposite (lower surface) side and the other side is formed. The end of the remaining flat plate portion is shaped as a convex portion, but at one end portion of the arc-shaped member, a convex portion is formed on both sides of the cut-out concave portion by cutting out the central portion of the plate thickness. It is good also as a shape which formed the recessed part in both sides so that the center part of plate | board thickness may be a convex part in the other edge part.

On the other hand, when it is set as a brick stacked structure like the support ring of 2nd Embodiment, you may stack in two or more steps. Further, the number of arc-shaped members in one ring row structure may be the same in each stage, or may be changed for each stage. You may make it change the number of circular-arc-shaped members by the ring row structure on the side which forms a plasma opposing surface, and another ring row structure.
Furthermore, the configuration of the present invention can be applied not only to the support ring but also to the focus ring and the shield ring.

DESCRIPTION OF SYMBOLS 1 Plasma etching apparatus 2 Vacuum chamber 3 Electrode plate (upper electrode)
4 frame (lower electrode)
5 Insulator 6 Electrostatic chuck 7 Support ring 8 Wafer (substrate to be processed)
16 Plasma generation region 17 Shield ring 21, 21A, 21B Arc-shaped member 22, 23 Projection portion 24 Flat plate portion 25 Recess portion 27 Flat plate portion 28 Recess portion 31 Plasma facing surface 33 Adhesive 34 Abutting surface 35 Adhering region 41 Support rings 42, 42A. 42B Arc-shaped member 43, 44 Ring row structure

Claims (2)

  A silicon ring in which one of the front and back surfaces is a plasma facing surface directed toward the plasma generation region, and a plurality of arc-shaped members are arranged in the circumferential direction and fixed in a ring shape, and the two arc-shaped members adjacent to each other Between the end portions, a concave portion formed by cutting a part of the range of the plate thickness of each arc-shaped member along the plasma facing surface and a convex portion that engages with the concave portion are formed. A silicon for a plasma processing apparatus, wherein an adhesive for fixing each arc-shaped member is provided between the engaging surfaces of the plurality of arc-shaped members so as to avoid between the butting surfaces of the arc-shaped members exposed to the plasma facing surface. ring.   A silicon ring in which one of the front and back surfaces is a plasma facing surface directed toward the plasma generation region, and a plurality of ring array structures in which a plurality of arc-shaped members are arranged in the circumferential direction are stacked in the plate thickness direction, Adhesive that is arranged in such a manner that the abutting surfaces between the arc-shaped members are shifted in the circumferential direction between the upper and lower adjacent ring row components, and fixes the arc-shaped members between the laminated surfaces of these ring row members However, the silicon ring for a plasma processing apparatus is provided so as to avoid a space between the butted surfaces of the arcuate members exposed on the plasma facing surface.

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