JP2016022561A - PERFORATION METHOD OF SiC MEMBER - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a perforation method of an SiC member which can efficiently form a through hole having a predetermined diameter on the SiC member having a CVD-SiC layer.SOLUTION: An auxiliary electrode layer is formed on a surface of a CVD-SiC layer of an SiC member formed of an SiC substrate and the CVD-SiC layer (S1). A voltage is applied between a first electrode and the auxiliary electrode layer while rotating the first electrode around a center axis, and a first hole which does not penetrate the SiC substrate is formed by electric discharge machining (S2). A voltage is applied between a second electrode and the auxiliary electrode layer while rotating the second electrode thinner than the first electrode around a center axis, and a second hole which penetrates the SiC substrate and the CVD-SiC layer from a bottom part of the first hole and has a predetermined diameter is formed by the electric discharge machining (S3). Then, the auxiliary electrode layer is removed from the surface of the CVD-SiC layer (S4), and the SiC member is wet-cleaned (S5).SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method of drilling a SiC (silicon carbide) member, and more particularly to a method of forming a through-hole having a predetermined diameter in a SiC member having a CVD-SiC layer produced by a CVD (chemical vapor deposition) method.

In the semiconductor device manufacturing process, as shown in FIG. 8, a reaction gas G is introduced into the chamber 1, and a lower electrode 2 that also serves as a mounting table for the substrate S is provided so as to face the lower electrode 2. A plasma processing apparatus is used in which plasma is generated by applying a high-frequency voltage to the upper electrode 3 and the substrate S is subjected to plasma etching processing by this plasma. At this time, in order to perform an accurate process over the entire surface of the substrate S, it is necessary to supply the reaction gas G evenly to the plasma generation region in the chamber 1, and usually a shower in which a large number of through holes 4 are arranged. The reaction gas G is introduced through the head 5.
In such a plasma processing apparatus, the surface of the member used in the chamber 1 may be eroded by contact with plasma. In particular, the shower head 5 is disposed immediately above the substrate S to be processed and is in direct contact with the plasma. Adhering to the surface of the substrate S causes generation of particles.

  Thus, for example, Patent Document 1 proposes a shower head in which a CVD-SiC layer formed by a CVD method is disposed on a base material portion made of sintered SiC. Since the CVD-SiC layer has a dense structure and is not easily eroded even when exposed to plasma, the surface on which this CVD-SiC layer is formed faces the plasma generation region, and the shower head is placed in the chamber. By arranging, generation of particles can be prevented.

JP 2005-285845 A

However, the CVD-SiC layer is not easy to process due to the dense structure, and a method of forming a large number of through holes for reaction gas distribution has been a problem.
In Patent Document 1, the through-hole is formed by machining such as drilling. However, when a CVD-SiC layer is drilled using a drill bit, the drill bit blade is heavily worn, and several through-holes are formed. There is a problem that the drill bit has to be replaced. Further, in the drilling process, there is a possibility that the peripheral portion of the through hole is missing when the through hole is formed.
In addition, instead of machining, attempts have been made to drill a CVD-SiC layer by ultrasonic processing, but the operation of the ultrasonic processing apparatus is complicated and a skilled operator is required to obtain high processing accuracy. It is necessary to apply ultrasonic vibrations to the tool while supplying abrasive liquid in which abrasive grains such as diamond are dispersed around the tool, the drilling speed is slow and it takes a long time to form a through hole, and automation is difficult. This is not a practical method for some reason.

  The present invention has been made to solve such a conventional problem, and provides a SiC member perforation method capable of efficiently forming a through-hole having a predetermined diameter in a SiC member having a CVD-SiC layer. The purpose is to provide.

  In the SiC member drilling method according to the present invention, a through hole having a predetermined diameter is formed in a SiC member in which a CVD-SiC layer having an electrical resistivity higher than that of the SiC substrate is formed on the surface of the SiC substrate. A first step of forming an auxiliary electrode layer on the surface of the CVD-SiC layer, and a first electrode extending along the central axis of the through-hole to be formed is rotated about the central axis While applying a voltage between the first electrode and the auxiliary electrode layer, the first electrode is moved relative to the SiC member along the central axis, and the SiC substrate is larger than a predetermined diameter by electric discharge machining. A second step of forming a first hole that does not penetrate through the diameter, and a second electrode that extends along the central axis and is narrower than the first electrode is inserted into the first hole formed in the SiC substrate. While rotating around the central axis A voltage is applied between the electrode and the auxiliary electrode layer, and the second electrode is moved relative to the SiC member, and is discharged through the SiC substrate and the CVD-SiC layer from the bottom of the first hole by electric discharge machining. And a third step of forming a second hole having a diameter of.

Preferably, the first electrode has a hollow pipe shape inside, and the first hole is formed in the SiC substrate while circulating the cooling fluid inside the first electrode. The first electrode can be formed from Cu or W.
The second electrode preferably has a wire shape. The second electrode can be formed of W or an alloy of W.
The auxiliary electrode layer can be formed by coating.
The SiC substrate is made of sintered SiC having an electrical resistivity of less than 1 MΩcm, and the CVD-SiC layer preferably has an electrical resistivity of 1 MΩcm or more.

In the second step and the third step, the SiC member is placed on the base plate so that the auxiliary electrode layer formed on the surface of the CVD-SiC layer in the first step faces the surface of the base plate. It is preferable that the groove is formed in advance on the surface of the base plate in accordance with the formation position of the through hole.
Moreover, the 4th process of removing an auxiliary electrode layer from the surface of a CVD-SiC layer, and the 5th process of wet-cleaning a SiC member can also be provided.
Furthermore, the shower head used for the plasma etching process can be manufactured by forming a plurality of through holes having a predetermined diameter in the SiC member.

  According to the present invention, an auxiliary electrode layer is formed on the surface of the CVD-SiC layer, and a voltage is applied between the first electrode and the auxiliary electrode layer while rotating the first electrode around the central axis. After the first hole having a diameter larger than the predetermined diameter is formed in the SiC substrate by electric discharge machining, the second electrode thinner than the first electrode is inserted into the first hole formed in the SiC substrate. Then, while rotating around the central axis, a voltage is applied between the second electrode and the auxiliary electrode layer, and a predetermined diameter penetrating the SiC substrate and the CVD-SiC layer from the bottom of the first hole by electric discharge machining. Therefore, it is possible to efficiently form a through hole having a predetermined diameter in the SiC member having the CVD-SiC layer.

It is side surface sectional drawing which shows the SiC member in which the through-hole was formed by the drilling method which concerns on embodiment of this invention. It is a block diagram which shows the punching apparatus for implementing the punching method which concerns on embodiment. It is a flowchart which shows operation | movement of the drilling method which concerns on embodiment. It is side surface sectional drawing which shows a mode that the 1st hole is formed in a SiC substrate in embodiment. It is a block diagram which shows the state of the perforation apparatus at the time of forming a 2nd hole in a SiC member. It is side surface sectional drawing which shows a mode that the 2nd hole is formed in a SiC member in embodiment. It is side surface sectional drawing which shows the SiC member in which the several through-hole was formed. It is sectional drawing which shows the structure of a plasma processing apparatus.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows an SiC member 11 having through holes formed by the drilling method according to the embodiment. The SiC member 11 is formed by laminating a CVD-SiC layer 13 having a thickness T2 on the surface of a SiC substrate 12 having a thickness T1 made of sintered SiC. Sintered SiC constituting the SiC substrate 12 has an electrical resistivity of less than 1 MΩcm, and SiC formed by the CVD method constituting the CVD-SiC layer has an electrical resistivity of 1 MΩcm or more.

  A first hole 14 having a diameter D1 is formed in the SiC substrate 12 from a surface opposite to the surface on which the CVD-SiC layer 13 is formed. The first hole 14 does not penetrate the SiC substrate 12 and has a depth H1 that is smaller than the thickness T1 of the SiC substrate 12. Further, a second hole 15 having a common central axis C <b> 1 with the first hole 14 is formed so as to penetrate the SiC substrate 12 and the CVD-SiC layer 13 from the bottom of the first hole 14. That is, the second hole 15 has a depth H2 larger than the thickness T2 of the CVD-SiC layer 13. Further, the second hole 15 has a diameter D2 smaller than the diameter D1 of the first hole 14, and this diameter D2 corresponds to a predetermined diameter of a desired through hole formed in the SiC member 11. doing.

  FIG. 2 shows a configuration of a drilling device for performing the drilling method according to the first embodiment. The perforating apparatus has a stage 21 mounted and held with the SiC member 11 and movable in three XYZ directions. A stage moving unit 22 for moving the stage 21 is connected to the stage 21. Has been. Base plate 31 is arranged on stage 21, and SiC member 11 is held in a state of being placed on the surface of base plate 31. It is assumed that a groove 31 </ b> A made of a circular depression is formed on the surface of the base plate 31 in advance in accordance with the position of the through hole formed in the SiC member 11.

Above the stage 21, a first electrode 23 extending along a central axis C <b> 2 facing in a direction perpendicular to the surface of the stage 21 is disposed. The first electrode 23 is formed of Cu (copper) and has a hollow pipe shape inside, and is arranged so as to be rotatable around the central axis C2. An electrode rotating unit 24 that rotates and drives the first electrode 23 around the central axis C2 to the first electrode 23, and a cooling fluid is circulated through the hollow interior of the first electrode 23, thereby the first electrode 23 The refrigerant supply unit 25 that cools the refrigerant 23 is connected to each other.
The perforating apparatus further includes a machining power supply unit 26 for applying a voltage for electric discharge machining between the SiC member 11 mounted on the stage 21 and the first electrode 23, and the stage moving unit 22, the electrode A control unit 27 is connected to the rotating unit 24, the refrigerant supply unit 25, and the machining power supply unit 26.

Next, the drilling method according to the embodiment will be described with reference to the flowchart of FIG.
First, in step S1, as shown in FIG. 2, the auxiliary electrode layer 32 is formed on the surface of the CVD-SiC layer 13 of the SiC member 11 in which the SiC substrate 12 and the CVD-SiC layer 13 are laminated. The auxiliary electrode layer 32 is made of, for example, Ni (nickel) and can be formed by a coating method.
Then, the SiC member 11 is placed on the base plate 31 with the SiC substrate 12 facing upward so that the auxiliary electrode layer 32 faces the surface of the base plate 31 and is held on the stage 21.

  Further, the machining power supply unit 26 is connected to the auxiliary electrode layer 32 and the first electrode 23 formed on the surface of the CVD-SiC layer 13, and the first electrode 23 is controlled under the control of the control unit 27 in step S 2. The first hole 14 that does not penetrate the SiC substrate 12 is formed by electric discharge machining. At this time, the first electrode 23 is driven to rotate around the central axis C2 by the electrode rotating unit 24 controlled by the control unit 27, and the cooling fluid is supplied into the hollow interior of the first electrode 23 by the refrigerant supply unit 25. Furthermore, the stage 21 is raised by the stage moving unit 22 in a state where a voltage is applied between the auxiliary electrode layer 32 and the first electrode 23 by the processing power supply unit 26. In addition, the rotational speed of the 1st electrode 23 by the electrode rotation part 24 can be 10-1000 times / min (RPM), for example.

  Thereby, the first electrode 23 approaches relatively to the SiC substrate 12 along the central axis C2, and the arc discharge occurs when the distance between the first electrode 23 and the auxiliary electrode layer 32 reaches a predetermined value. It is generated and the SiC substrate 12 is processed in a locally high temperature state. As the stage 21 rises, the electric discharge machining gradually progresses to the inside of the SiC substrate 12, and the stage 21 is continuously raised by the stage moving unit 22, so that the thickness of the SiC substrate 12 is increased as shown in FIG. A first hole 14 having a depth H1 smaller than T1 and not penetrating SiC substrate 12 is formed.

Of the SiC substrate 12 and the CVD-SiC layer 13 of the SiC member 11, the first hole 14 is formed from the side of the SiC substrate 12 having a relatively small electrical resistivity, so that the auxiliary electrode layer 32 is a CVD-SiC layer. If it spreads on the surface of 13, it can fully perform electric discharge machining, for example, it is not necessary to form the auxiliary electrode layer 32 by a sputtering method or a vapor deposition method. Therefore, drilling can be easily performed with a simple device.
In addition, since the first electrode 23 is rotationally driven around the central axis C2 by the electrode rotating unit 24, the SiC substrate 12 can be efficiently processed by electric discharge, and further, the first electrode can be obtained by the coolant supply unit 25. Since the cooling fluid is circulated through the hollow portion 23, electric discharge machining can proceed without damaging the first electrode 23 due to high temperature.

  After forming the first hole 14 not penetrating the SiC substrate 12 in this way, as shown in FIG. 5, the second electrode 28 is set in the perforating apparatus instead of the first electrode 23, and step S3 Thus, under the control of the control unit 27, the second hole 15 penetrating the SiC substrate 12 and the CVD-SiC layer 13 from the bottom 14A of the first hole 14 is formed by electric discharge machining using the second electrode 28. . At this time, the base plate 31 and the SiC member 11 held on the stage 21 are not moved with respect to the stage 21, and maintain the same position and posture as when the first hole 14 is formed.

Here, the second electrode 28 is made of W (tungsten), has a wire shape thinner than that of the first electrode 23, and is rotated around the central axis C2 common to the first electrode 23 by the electrode rotating unit 24. It is assumed that it is rotationally driven.
The second electrode 28 is rotationally driven around the central axis C2 by the electrode rotating unit 24 controlled by the control unit 27, and the first hole 14 along the outer peripheral portion of the second electrode 28 by the refrigerant supply unit 25. The stage 21 is raised by the stage moving unit 22 in a state where a cooling fluid is circulated inside and a voltage is applied between the auxiliary electrode layer 32 and the second electrode 28 by the processing power supply unit 26. In addition, the rotational speed of the 2nd electrode 28 by the electrode rotation part 24 can be 10-1000 times / min (RPM), for example.

  As the stage 21 is raised, the second electrode 28 is inserted into the first hole 14 formed in the SiC substrate 12, and the tip of the second electrode 28 is inserted into the bottom 14 </ b> A of the first hole 14. When approaching, arc discharge is generated, and the SiC substrate 12 and the CVD-SiC layer 13 are sequentially processed. By continuing the ascent of the stage 21 by the stage moving unit 22, as shown in FIG. 6, the second that penetrates the SiC substrate 12, the CVD-SiC layer 13 and the auxiliary electrode layer 32 from the bottom 14 </ b> A of the first hole 14. Hole 15 is formed.

At this time, since the second electrode 28 is rotationally driven around the central axis C2 by the electrode rotating unit 24, the SiC substrate 12 and the CVD-SiC layer 13 can be efficiently discharged. Further, since the cooling fluid is circulated in the first hole 14 along the outer peripheral portion of the second electrode 28 by the refrigerant supply unit 25, the electric discharge machining is performed without damaging the second electrode 28 due to high temperature. Can be advanced.
Further, since the groove 31 </ b> A is formed in advance on the surface of the base plate 31 in accordance with the formation position of the second hole 15, the cooling fluid and the cutting waste accompanying the formation of the second hole 15 are the second hole 15. Is discharged downward and accommodated in the groove 31A.

Thereafter, in step S4, the auxiliary electrode layer 32 is removed from the surface of the CVD-SiC layer 13 by etching or the like. Further, in the subsequent step S5, the SiC member 11 is wet-washed, rinsed with water, and dried. The production of the SiC member 11 in which the first hole 14 and the second hole 15 as shown in FIG. 1 are formed is completed.
The wet cleaning can be performed by sulfuric acid / hydrogen peroxide cleaning using a piranha solution, an ultra-high purity buffered hydrofluoric acid (BHF) bath, or the like.

  The diameter of the first electrode 23 and the diameter of the second electrode 28 are selected according to a predetermined diameter of a desired through hole to be formed in the SiC member 11. For example, the CVD-SiC is applied to the SiC member 11 in which the CVD-SiC layer 13 having a thickness T2 = 2.2 mm is formed on the surface of the SiC substrate 12 made of sintered SiC having a thickness T1 = 9.0 mm. When the second hole 15 having a diameter D2 = 0.5 mm is formed on the layer 13 side, first, the diameter D1 = 1.0 mm and the depth H1 = 7.7 using the first electrode 23 having a diameter of 0.9 mm. After forming the first hole 14 of ˜8.5 mm, the diameter penetrating the SiC substrate 12 and the CVD-SiC layer 13 from the bottom 14 </ b> A of the first hole 14 using the second electrode 28 having a diameter of 0.4 mm. A second hole 15 having D2 = 0.5 mm can be formed.

  The first hole 14 serves as a flow path for the cooling fluid and the cutting waste when forming the second hole 15, and is therefore larger by 0.1 mm or more than a predetermined diameter D2 planned as the second hole 15. The first hole 14 is preferably formed using the first electrode 23 having a diameter. That is, when forming the second hole 15 having a diameter D2 = 0.5 mm, it is preferable to use the first electrode 23 having a diameter of 0.6 mm or more.

  As described above, the auxiliary electrode layer 32 is formed on the surface of the CVD-SiC layer 13 by coating, and the first electrode 23 does not penetrate the SiC substrate 12 by electric discharge machining while rotating the first electrode 23 about the central axis C2. After the hole 14 is formed, the second electrode 28 thinner than the first electrode 23 is inserted into the first hole 14 and rotated around the central axis C2, and the bottom of the first hole 14 is formed by electric discharge machining. Since the second hole 15 penetrating through the SiC substrate 12 and the CVD-SiC layer 13 is formed from, the through hole having a predetermined diameter can be efficiently formed in the SiC member 11.

In particular, when the first hole 14 is formed and when the second hole 15 is formed, the SiC member 11 held on the stage 21 does not need to be turned over so as to reverse the vertical direction. The position can be kept fixed with respect to the hole, so that although the two kinds of holes 14 and 15 are formed, the alignment work between them becomes unnecessary, and the drilling work can be carried out extremely efficiently and with high accuracy. Can do.
In addition, since the electric discharge machining is performed while moving the stage 21 by the stage moving unit 22, automation can be easily achieved.

Similarly, as shown in FIG. 7, if a SiC member 41 in which a plurality of through holes each having a first hole 14 and a second hole 15 are formed at a predetermined pitch P is produced, FIG. It can be used as a shower head that distributes the reaction gas evenly in the chamber of the plasma processing apparatus as shown in FIG. In this case, for example, the SiC member 41 in which a large number of through holes of 1000 or more are formed can be used.
By arranging the shower head made of the SiC member 41 in the chamber with the surface on which the CVD-SiC layer 13 is formed facing the plasma generation region, generation of particles can be prevented.

  In the case of forming such a plurality of through holes, by performing electric discharge machining using the first electrode 23 while moving the stage 21 by the stage moving unit 22 in step S2 of the flowchart shown in FIG. After forming the plurality of first holes 14 in the SiC substrate 12, the electric discharge machining is performed by using the second electrode 28 while moving the stage 21 by the stage moving unit 22 in step S3. A second hole 15 that penetrates the SiC substrate 12 and the CVD-SiC layer 13 from the bottom of the first hole 14 may be formed inside the first hole 14.

In the above embodiment, the SiC substrate 12 is formed of sintered SiC. However, the present invention is not limited to this, and the hot press is not limited to this as long as it has a lower electrical resistivity than the CVD-SiC layer 13. It is also possible to use SiC formed by CVD or SiC formed by CVD.
Moreover, although the 1st electrode 23 was formed from Cu, it is not restricted to this, For example, it can also form from W. Furthermore, in addition to W, the second electrode 28 can be made of W alloy, Mo (molybdenum), Mo alloy, or the like.

  11, 41 SiC member, 12 SiC substrate, 13 CVD-SiC layer, 14 1st hole, 14A bottom part, 15 2nd hole, 21 stage, 22 stage moving part, 23 1st electrode, 24 electrode rotating part, 25 Refrigerant supply section, 26 Processing power supply section, 27 Control section, 28 Second electrode, 31 Base plate, 31A Groove, 32 Auxiliary electrode layer, T1 SiC substrate thickness, T2 CVD-SiC layer thickness, D1 first , D2 second hole diameter, H1 first hole depth, H2 second hole depth, C1, C2 central axis, P pitch.

Claims (10)

A method of forming a through-hole having a predetermined diameter in a SiC member in which a CVD-SiC layer having an electrical resistivity higher than that of the SiC substrate is formed on the surface of the SiC substrate,
A first step of forming an auxiliary electrode layer on the surface of the CVD-SiC layer;
A voltage is applied between the first electrode and the auxiliary electrode layer while rotating a first electrode extending along the central axis of the through-hole to be formed around the central axis, and the first electrode A second step of forming a first hole having a diameter larger than the predetermined diameter in the SiC substrate by electric discharge machining by moving the electrode relative to the SiC member along the central axis;
A second electrode that extends along the central axis and is thinner than the first electrode is inserted into the first hole formed in the SiC substrate and rotated around the central axis while rotating the second electrode. A voltage is applied between the electrode of the first electrode and the auxiliary electrode layer, and the second electrode is moved relative to the SiC member to discharge the SiC substrate and the CVD from the bottom of the first hole by electric discharge machining. A third step of forming the second hole having the predetermined diameter that penetrates the SiC layer. The first electrode has a hollow pipe shape inside,
2. The SiC member perforation method according to claim 1, wherein the first hole is formed in the SiC substrate while allowing a cooling fluid to flow through the first electrode.   3. The SiC member perforation method according to claim 2, wherein the first electrode is made of Cu or W. 4.   The SiC member perforation method according to claim 1, wherein the second electrode has a wire shape.   5. The SiC member perforating method according to claim 4, wherein the second electrode is made of W or an alloy of W.   The said auxiliary electrode layer is a punching method of the SiC member as described in any one of Claims 1-5 formed by application | coating.   The SiC substrate is made of sintered SiC having an electrical resistivity of less than 1 MΩcm, and the CVD-SiC layer has an electrical resistivity of 1 MΩcm or more. Drilling method.   In the second step and the third step, the SiC member is formed on the base plate so that the auxiliary electrode layer formed on the surface of the CVD-SiC layer in the first step faces the surface of the base plate. The SiC member perforation according to any one of claims 1 to 7, wherein a groove is formed in advance on the surface of the base plate in accordance with a formation position of the through hole. Method. A fourth step of removing the auxiliary electrode layer from the surface of the CVD-SiC layer;
The SiC member perforation method according to claim 1, further comprising: a fifth step of performing wet cleaning on the SiC member.   The drilling method of the SiC member according to any one of claims 1 to 9, wherein a shower head used for a plasma etching process is formed by forming a plurality of through holes having the predetermined diameter in the SiC member.

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