Member for semiconductor fabrication apparatus

Abstract

A wafer table 10 comprises: a ceramic plate 20 having a wafer-bearing surface 21 on an upper surface 20a; an RF electrode 22 embedded in the ceramic plate 20; a thermocouple insertion hole 24 provided in a section that extends from a lower surface of the ceramic plate 20 to just short of the RF electrode 22; and a dummy electrode 25 connected to ground G and provided in the portion of the ceramic plate 20 between the RF electrode 22 and a bottom surface 24a of the thermocouple insertion hole 24 to achieve electrical isolation from the RF electrode 22.

Description

Semiconductor manufacturing equipment components

[0001] The present invention relates to a member for a semiconductor manufacturing device.

[0002] A conventional semiconductor manufacturing equipment component includes a ceramic plate having a wafer mounting surface on its upper surface, an RF (radio frequency) electrode embedded in the ceramic plate, and a thermocouple insertion hole provided in a section from the lower surface of the ceramic plate to just before the RF electrode (see, for example, Patent Document 1). With this semiconductor manufacturing equipment component, plasma is generated in the space above the wafer with the wafer placed on the wafer mounting surface, and the plasma is used to perform CVD film deposition or etching on the wafer.

[0003] Patent No. 6843752

[0004] However, in Patent Document 1, when a wafer is processed at high temperatures using plasma, the thermocouple inserted into the thermocouple insertion hole acts as a lightning rod, which can cause arcing marks or cracks on the bottom surface of the thermocouple insertion hole. The mechanism by which arcing occurs is thought to be as follows: As the temperature rises, the volume resistivity of the ceramic plate decreases, generating a potential difference between the thermocouple and the RF electrode, causing the thermocouple to act as a lightning rod and causing arcing.

[0005] The present invention has been made to solve the above-mentioned problems, and a main object of the present invention is to prevent defects from occurring on the bottom surface of the thermocouple insertion hole.

[0006] [1] A semiconductor manufacturing equipment member of the present invention comprises: a ceramic plate having a wafer mounting surface on an upper surface thereof; an RF electrode embedded in the ceramic plate; a thermocouple insertion hole provided in a section from the lower surface of the ceramic plate to just before the RF electrode; and a dummy electrode provided on the ceramic plate between the RF electrode and a bottom surface of the thermocouple insertion hole so as to be electrically insulated from the RF electrode and connected to ground.

[0007] This semiconductor manufacturing equipment component includes a dummy electrode provided in the ceramic plate between the RF electrode and the bottom surface of the thermocouple insertion hole so as to be electrically insulated from the RF electrode. The dummy electrode is connected to ground. Therefore, the dummy electrode prevents discharge from occurring between the thermocouple and the RF electrode. This can suppress defects on the bottom surface of the thermocouple insertion hole.

[0008] In this specification, "upper" and "lower" do not represent absolute positional relationships, but rather relative positional relationships. Therefore, depending on the orientation of the semiconductor manufacturing equipment component, "upper" and "lower" may become "lower" and "upper," "left" and "right," or "front" and "rear."

[0009] [2] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member described in [1] above), the dummy electrode may also be provided in an area of ​​the ceramic plate surrounding the side surface of the thermocouple insertion hole. This makes it possible to more effectively prevent discharge between the thermocouple and the RF electrode.

[0010] [3] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member described in [1] or [2] above), the dummy electrode may be provided so as not to be exposed to the inner surface of the thermocouple insertion hole. In this way, a thermocouple having a metal temperature measuring part can be used, and the temperature can be measured by bringing the temperature measuring part into contact with the inner surface of the thermocouple insertion hole, thereby improving the temperature measurement accuracy.

[0011] [4] In the semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member according to any one of [1] to [3] above), the ceramic plate may be an AlN plate. The volume resistivity of an AlN plate is likely to decrease when a wafer is processed at high temperatures using plasma, which makes it easy for discharge to occur between the RF electrode and the thermocouple. Therefore, the application of the present invention is highly significant.

[0012] [5] The semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member according to any one of [1] to [4] above) may include a heater electrode embedded in the ceramic plate below the RF electrode, and the heater electrode may be provided around the thermocouple insertion hole so as not to be exposed to the inner surface of the thermocouple insertion hole, and may be electrically insulated from the RF electrode and the dummy electrode. In this case, the bottom surface of the thermocouple insertion hole is located closer to the wafer mounting surface than the heater electrode, so that the temperature measuring part of the thermocouple can measure the temperature at a position closer to the wafer.

[0013] [6] The semiconductor manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member described in any one of [1] to [4] above) may include a cylindrical shaft that supports the ceramic plate from the underside of the ceramic plate, and an inner area of ​​the shaft surrounded by the cylindrical shaft on the underside of the ceramic plate may be provided with the thermocouple insertion hole, an RF electrode hole for inserting an RF electrode connecting member connected to the RF electrode, and a dummy electrode hole for inserting a dummy electrode connecting member connected to the dummy electrode. In this case, because the thermocouple insertion hole and the RF electrode hole are located relatively close to each other, any defect in the bottom surface of the thermocouple insertion hole may affect the RF electrode. Therefore, the application of the present invention is highly significant.

[0014] [7] In the manufacturing equipment member of the present invention (the semiconductor manufacturing equipment member according to any one of [1] to [6] above), the RF electrode, the dummy electrode, and the thermocouple insertion hole may overlap when the semiconductor manufacturing equipment member is viewed from above. In this case, the dummy electrode blocks the shortest distance between the RF electrode and the thermocouple insertion hole, thereby more effectively preventing discharge between the thermocouple and the RF electrode.

[0015] In addition, when the semiconductor manufacturing equipment member is provided with a heater electrode like the semiconductor manufacturing equipment member described in [5] above, a heater electrode hole into which a heater electrode connecting member connected to the heater electrode is inserted may also be provided in the shaft inner region.

[0016] 1 is a perspective view of the wafer mounting table 10. FIG. 2 is a cross-sectional view taken along the line AA in FIG.

[0017] A preferred embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a perspective view of a wafer mounting table 10, and Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1. The wafer mounting table 10 is an example of a semiconductor manufacturing equipment member of the present invention.

[0018] The wafer mounting table 10 is used to heat a wafer W undergoing processing such as etching or CVD, and is installed in a vacuum chamber (not shown). The wafer mounting table 10 includes a ceramic plate 20 having a wafer mounting surface 21 on its upper surface 20a, and a cylindrical shaft 40 joined to the lower surface 20b of the ceramic plate 20.

[0019] The ceramic plate 20 is a disk-shaped plate made of a ceramic material, such as aluminum nitride or alumina. The diameter of the ceramic plate 20 is not particularly limited, but is, for example, 300 to 400 mm. A circular wafer mounting surface 21 is provided on the upper surface 20a of the ceramic plate 20. Although not shown, the wafer mounting surface 21 is provided with an annular seal band along the outer edge of the wafer mounting surface 21 in a plan view, and multiple small protrusions are provided on the entire inner surface of the seal band. The height of the seal band and the height of the small protrusions are the same. As shown in FIG. 2 , a circular shaft inner region 29 surrounded by a cylindrical shaft 40 is provided on the lower surface 20b of the ceramic plate 20.

[0020] An RF electrode 22, a heater electrode 23, and a dummy electrode 25 are embedded in the ceramic plate 20. The RF electrode 22 is embedded in a position close to the wafer mounting surface 21, the heater electrode 23 is embedded in a position away from the wafer mounting surface 21, and the dummy electrode 25 is embedded between the RF electrode 22 and the heater electrode 23. The ceramic plate 20 has a thermocouple insertion hole 24. The thermocouple insertion hole 24 is provided in a section from the lower surface of the ceramic plate 20 to just before the RF electrode 22. The dummy electrode 25 is provided in the ceramic plate 20 between the RF electrode 22 and a bottom surface 24a of the thermocouple insertion hole 24 so as not to come into contact with the RF electrode 22 or the heater electrode 23, i.e., so as to be electrically insulated from the RF electrode 22 or the heater electrode 23. The distance between the RF electrode 22 and the bottom surface 24a of the thermocouple insertion hole 24 is not particularly limited, but is, for example, 1 to 3 mm (e.g., 2 mm).

[0021] The RF electrode 22 is a circular electrode used to generate plasma above the wafer mounting surface 21, and is formed of, for example, a metal mesh. The diameter of the RF electrode 22 is slightly smaller than the diameter of the ceramic plate 20. The RF electrode 22 is provided with an RF electrode terminal 22a. The RF electrode terminal 22a is exposed to the outside through an RF electrode hole 26 formed in the shaft inner region 29. The RF electrode terminal 22a is joined to a rod-shaped RF electrode connecting member 42 inserted into the RF electrode hole 26. The RF electrode connecting member 42 is provided so as to pass through the inside of the cylindrical shaft 40. Examples of materials for the RF electrode 22 include Mo, W, MoC, and WC.

[0022] The heater electrode 23 is embedded below the RF electrode 22. The heater electrode 23 is formed by a resistance heating element that originates from one of a pair of terminals 23a, 23b, is folded back at multiple folds in a single stroke, and is wired across substantially the entire wafer mounting surface 21 in a plan view, and then reaches the other of the pair of terminals 23a, 23b. The pair of terminals 23a, 23b of the heater electrode 23 are exposed to the outside through heater electrode holes 27a, 27b formed in the shaft inner region 29, respectively. The pair of terminals 23a, 23b are joined to rod-shaped heater electrode connecting members 43a, 43b inserted into the heater electrode holes 27a, 27b, respectively. The heater electrode connecting members 43a, 43b are provided to pass through the interior of the cylindrical shaft 40 and are connected to a heater power source (not shown). The resistive heating element constituting the heater electrode 23 may be in the form of, for example, a coil, mesh, foil, or ribbon (wire). The resistive heating element may be formed by printing. The resistive heating element may be made of, for example, Mo, W, a Mo / W alloy, Nb, WC—TiN, or WC—Al2O3. The resistive heating element is provided so as to bypass the thermocouple insertion hole 24, the RF electrode hole 26, and the dummy electrode hole 28.

[0023] The dummy electrode 25 is a planar circular electrode formed of, for example, a metal mesh. The dummy electrode 25 is provided so as not to come into contact with the RF electrode 22 or the heater electrode 23, i.e., so as to be electrically insulated from the RF electrode 22 or the heater electrode 23. The dummy electrode 25 has a through hole at a position through which the RF electrode hole 26 passes, the through hole having a diameter larger than that of the RF electrode hole 26. The diameter of the dummy electrode 25 is equal to or smaller than that of the RF electrode 22. The dummy electrode 25 may be sized to cover at least the inner shaft region 29 in a plan view. The dummy electrode 25 is provided so as not to be exposed to the inner surface of the thermocouple insertion hole 24. A dummy electrode terminal 25a is provided on the dummy electrode 25. The dummy electrode terminal 25a is exposed to the outside through a dummy electrode hole 28 provided in the inner shaft region 29. The dummy electrode terminal 25a is joined to a rod-shaped dummy electrode connecting member 45 inserted into the dummy electrode hole 28. The dummy electrode connecting member 45 is provided so as to pass through the inside of the cylindrical shaft 40 and is connected to the ground G. Examples of materials for the dummy electrode 25 include Mo, W, MoC, and WC.

[0024] The cylindrical shaft 40 is made of a ceramic material such as aluminum nitride or alumina, like the ceramic plate 20. The cylindrical shaft 40 supports the ceramic plate 20 from the lower surface 20b of the ceramic plate 20. The outer diameter of the cylindrical shaft 40 is smaller than the diameter of the ceramic plate 20. The upper end of the cylindrical shaft 40 is diffusion-bonded to the ceramic plate 20. A flange may be provided at the upper end of the cylindrical shaft 40.

[0025] A thermocouple 44 for measuring the temperature near the center of the ceramic plate 20 is also disposed inside the cylindrical shaft 40. The thermocouple 44 is inserted into the thermocouple insertion hole 24. A metal temperature measuring part 44m provided at the tip of the thermocouple 44 is in direct contact with the ceramic plate 20 (the bottom surface 24a of the thermocouple insertion hole 24). The bottom surface 24a of the thermocouple insertion hole 24 is located above the heater electrode 23.

[0026] Next, an example of how the wafer mounting table 10 is used will be described. First, the wafer mounting table 10 is installed in a vacuum chamber (not shown), and a wafer W is placed on the wafer mounting surface 21 of the wafer mounting table 10. An upper electrode for generating plasma is disposed above the wafer mounting surface 21 in the vacuum chamber. Then, the power supplied to the heater electrode 23 is adjusted so that the temperature detected by the thermocouple 44 reaches a predetermined target high temperature. This controls the temperature of the wafer W to a desired temperature. The vacuum chamber is then set to a vacuum or reduced-pressure atmosphere, and plasma is generated in the vacuum chamber. This plasma is used to perform CVD film formation or etching on the wafer W. The plasma is generated by grounding one of the upper electrode and the RF electrode 22 and applying a high-frequency voltage to the other.

[0027] When processing the wafer W at high temperatures using plasma in this manner, if the dummy electrode 25 were not present, the thermocouple 44 inserted into the thermocouple insertion hole 24 would function as a lightning rod, causing discharge between the RF electrode 22 and the thermocouple 44, which could result in arcing marks or cracks on the bottom surface 24a of the thermocouple insertion hole 24. In contrast, the present embodiment includes the dummy electrode 25. Therefore, the dummy electrode 25 prevents discharge from occurring between the RF electrode 22 and the thermocouple 44.

[0028] The wafer mounting table 10 described above includes a dummy electrode 25 provided on the ceramic plate 20 between the RF electrode 22 and the bottom surface 24a of the thermocouple insertion hole 24 so as to be electrically insulated from the RF electrode 22. The dummy electrode 25 is connected to the ground G. Therefore, the dummy electrode 25 prevents discharge from occurring between the RF electrode 22 and the thermocouple 44. This makes it possible to prevent defects (e.g., arcing marks and cracks) from occurring on the bottom surface 24a of the thermocouple insertion hole 24.

[0029] Furthermore, the dummy electrode 25 is provided so as not to be exposed to the inner surface of the thermocouple insertion hole 24. This allows the use of a thermocouple 44 having a metal temperature measuring portion 44m, with the temperature measuring portion 44m in contact with the bottom surface 24a of the thermocouple insertion hole 24 to measure the temperature, thereby improving the accuracy of temperature measurement.

[0030] Furthermore, the ceramic plate 20 may be an AlN plate. Since the volume resistivity of an AlN plate is likely to decrease when a wafer W is processed at high temperatures using plasma, discharge is likely to occur between the RF electrode 22 and the thermocouple 44. For this reason, the application of the present invention is highly significant.

[0031] Furthermore, the wafer mounting table 10 includes a heater electrode 23 embedded in the ceramic plate 20 below the RF electrode 22, and the heater electrode 23 is provided around the thermocouple insertion hole 24 so as not to be exposed to the inner surface of the thermocouple insertion hole 24. The dummy electrode 25 is electrically insulated from the heater electrode 23. In this case, the bottom surface 24a of the thermocouple insertion hole 24 is located closer to the wafer mounting surface 21 than the heater electrode 23, so that the temperature measuring portion 44m of the thermocouple 44 can measure the temperature at a position closer to the wafer W, and can measure a temperature close to the temperature of the wafer W.

[0032] Furthermore, the shaft inner region 29 is provided with the thermocouple insertion hole 24, the RF electrode hole 26, the heater electrode holes 27a and 27b, and the dummy electrode hole 28. In this case, the thermocouple insertion hole 24 and the RF electrode hole 26 are located relatively close to each other, and the thermocouple insertion hole 24 and the heater electrodes 27a and 27b are also located relatively close to each other. Therefore, if a defect occurs on the bottom surface of the thermocouple insertion hole 24, it may affect the RF electrode 22 and the heater electrode 23. Therefore, there is great significance in applying the present invention.

[0033] Furthermore, when the wafer mounting table 10 is viewed from above, the RF electrode 22, the dummy electrode 25, and the thermocouple insertion hole 24 overlap with each other. As a result, the dummy electrode 25 blocks the shortest distance between the RF electrode 22 and the thermocouple insertion hole 24, so that discharge between the thermocouple 44 and the RF electrode 22 can be more effectively prevented.

[0034] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms as long as they fall within the technical scope of the present invention.

[0035] Although the wafer mounting table 10 described above employs a flat dummy electrode 25, the present invention is not limited thereto. For example, a dummy electrode 75 made of metal mesh and having a bottomed cylindrical (cup-like) shape may be employed, as in the wafer mounting table 110 shown in FIG. 3 . In FIG. 3 , the same components as those in the above-described embodiment are denoted by the same reference numerals. The dummy electrode 75 includes a circular horizontal portion 75a that covers the bottom surface 24a of the thermocouple insertion hole 24 in a plan view, and a cylindrical portion 75b connected to the horizontal portion 75a and provided in an area surrounding the side surface of the thermocouple insertion hole 24. The horizontal portion 75a is disposed between the RF electrode 22 and the bottom surface 24a of the thermocouple insertion hole 24. The horizontal portion 75a and the cylindrical portion 75b are not exposed to the inner surface of the thermocouple insertion hole 24 and are not in contact with the RF electrode 22 or the heater electrode 23. A dummy electrode connecting member 95 connected to the ground G is connected to the dummy electrode 75. This configuration also achieves the same effects as those in the above-described embodiment. Furthermore, since the cylindrical portion 75b of the dummy electrode 75 is provided in a region of the ceramic plate 20 that surrounds the side surface of the thermocouple insertion hole 24, it is possible to more effectively prevent discharge from occurring between the RF electrode 22 and the thermocouple 44. The horizontal portion 75a may be the same size as the dummy electrode 25.

[0036] In the above-described wafer mounting table 10, the RF electrode 22 may also serve as an electrostatic electrode. In this case, the RF electrode 22 is also connected to a DC power supply. When a DC current is applied to the RF electrode 22, the wafer W is attracted to the wafer mounting surface 21, and when the application of the DC current to the RF electrode 22 is stopped, the wafer W is released from the wafer mounting surface 21. Alternatively, an electrostatic electrode may be embedded separately from the RF electrode 22. In this case, the electrostatic electrode is embedded between the RF electrode 22 and the wafer mounting surface 21. The same applies to the wafer mounting table 110.

[0037] In the wafer mounting table 10 described above, the heater electrode 23 is a resistance heating element wired across the entire wafer mounting surface 21 in a plan view, but this is not particularly limited. For example, the wafer mounting surface 21 may be divided into multiple zones in a plan view, and a heater electrode may be formed for each zone. This also applies to the wafer mounting table 110.

[0038] In the above-described wafer stage 10, the heater electrode 23 is embedded in the ceramic plate 20, but the heater electrode 23 does not have to be embedded. This also applies to the wafer stage 110.

[0039] The present invention can be used for components used in semiconductor manufacturing equipment, such as wafer mounting stages.

[0040] 10 wafer mounting table, 20 ceramic plate, 20a upper surface, 20b lower surface, 21 wafer mounting surface, 22 RF electrode, 22a RF electrode terminal, 23 heater electrode, 23a, 23b terminal, 24 thermocouple insertion hole, 24a bottom surface, 25 dummy electrode, 25a dummy electrode terminal, 26 RF electrode hole, 27a, 27b heater electrode hole, 28 dummy electrode hole, 29 shaft inner region, 40 cylindrical shaft, 42 RF electrode connecting member, 43a, 43b heater electrode connecting member, 44 thermocouple, 44m temperature measuring unit, 45 dummy electrode connecting member, 75 dummy electrode, 75a horizontal portion, 75b cylindrical portion, 95 dummy electrode connecting member, 110 wafer mounting table, G ground, W wafer.

Claims

1. A component for semiconductor manufacturing equipment comprising: a ceramic plate having a wafer mounting surface on its upper surface; an RF electrode embedded in said ceramic plate; a thermocouple insertion hole provided in the section from the underside of said ceramic plate to just before said RF electrode; and a dummy electrode provided on said ceramic plate between said RF electrode and the bottom surface of said thermocouple insertion hole so as to be electrically insulated from said RF electrode and connected to ground.

2. The semiconductor manufacturing equipment member according to claim 1, wherein the dummy electrodes are also provided in an area of ​​the ceramic plate that surrounds the side surface of the thermocouple insertion hole.

3. A semiconductor manufacturing equipment member according to claim 1 or 2, wherein the dummy electrode is provided so as not to be exposed to the inner surface of the thermocouple insertion hole.

4. The semiconductor manufacturing equipment member according to claim 1 or 2, wherein the ceramic plate is an AlN plate.

5. A component for semiconductor manufacturing equipment according to claim 1 or 2, comprising a heater electrode embedded in the ceramic plate below the RF electrode, the heater electrode being provided around the thermocouple insertion hole so as not to be exposed to the inner surface of the thermocouple insertion hole, and being electrically insulated from the RF electrode and the dummy electrode.

6. A component for semiconductor manufacturing equipment according to claim 1 or 2, comprising a cylindrical shaft that supports the ceramic plate from the underside of the ceramic plate, and in an area of ​​the underside of the ceramic plate surrounded by the cylindrical shaft, the thermocouple insertion hole, an RF electrode hole for inserting an RF electrode connecting member connected to the RF electrode, and a dummy electrode hole for inserting a dummy electrode connecting member connected to the dummy electrode are provided.

7. A semiconductor manufacturing equipment member according to claim 1 or 2, wherein the RF electrode, the dummy electrode, and the thermocouple insertion hole overlap when the semiconductor manufacturing equipment member is viewed from above.

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