JP2000114353A - Part for semiconductor processing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow semiconductor processing equipment utilizing a plasma to be used for a long time with stability without contaminating semiconductor wafers, by forming a high-purity silicon carbide sintered body layer with the average particle size of crystalline particles of a specific value or below on the surface of parts for use in the semiconductor processing equipment. SOLUTION: A high-purity silicon carbide sintered body layer, not more than 30 μm in the average particle size of its crystalline particles, is formed on the surface of parts for use in semiconductor processing equipment utilizing plasma, for example, a dummy ring 8. As a result, the ratio of large crystalline particles, which can fall out, present in the sintered body is minimized. Even if the sintered body or sintered body layer is exposed to a plasma, therefore, the crystalline particles are less prone to fall out of its surface. Thus, the mount of the surface wasted by plasma irradiation is reduced, production of particles is suppressed, and the semiconductor processing equipment is capable of being used for a long time with stability without contaminating semiconductor wafers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a component used in a semiconductor manufacturing apparatus using plasma.

[0002]

2. Description of the Related Art Conventionally, for example, a plasma etching apparatus is known as a kind of semiconductor manufacturing apparatus using plasma. This apparatus exposes a silicon surface by exposing only a photosensitive region in a photosensitive film by exposing a silicon wafer having undergone an exposure and development process to gas plasma. A pair of positive and negative electrode plates are arranged in a chamber constituting a plasma etching apparatus so as to be vertically separated from each other. A large number of through holes are formed in the upper electrode plate, and gas plasma is supplied through these through holes. A component called a dummy ring is arranged on the outer peripheral portion of the upper surface of the lower electrode plate. When plasma is processed, the outer peripheral portion of the bottom surface of the silicon wafer is supported by the dummy ring, and the central portion of the bottom surface is supported by the lower electrode plate.

If the inside of a chamber is contaminated with impurities such as particles during the manufacture of a semiconductor, it may adhere to a silicon wafer, making it impossible to form a pattern accurately. Therefore, many defective products are generated, and the yield is reduced. In addition, it has been pointed out that particularly in the etching apparatus using plasma, components exposed to gas plasma tend to be a source of particles.

Accordingly, in recent years, for components used in this type of apparatus, a change has been made from a material such as aluminum or carbon in which particles and the like are easily generated to another material in which particles are hardly generated.

[0005] Such new materials include, for example, 1) a high-purity silicon carbide sintered body, and 2) a film having a thickness of about several tens μm made of a high-purity silicon carbide sintered body. And the like are proposed. The high-purity silicon carbide sintered body has an average crystal grain size of 5
A dense body having a bulk density of at least 0 μm and a bulk density of at least 3.0 g / cm ³ is usually used.

[0006]

The material 2) obtained by coating carbon with a high-purity sintered silicon carbide film surely generates less particles than aluminum or carbon. However, since the thickness of the film is as thin as tens of μm, the film is consumed in a short time in the gas plasma irradiated portion, and the carbon base material may be exposed therefrom.

[0007] Similarly, the material 1) consisting of a single body of a high-purity silicon carbide sintered body surely generates less particles than aluminum or carbon. However, when used for a long period of time, large ones of the crystal grains in the surface layer fall off due to the irradiation of the gas plasma, which causes the generation of particles.

As described above, even if a component is manufactured using the material of 1) or 2), it has not been possible to use the component stably for a long time. The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a component for a semiconductor manufacturing apparatus that can be stably used for a long time without worrying about contamination of a semiconductor wafer. .

[0009]

In order to solve the above problems, according to the first aspect of the present invention, there is provided a component used in a semiconductor manufacturing apparatus utilizing a plasma, wherein at least a surface layer of the component has crystal grains. The gist is a component for a semiconductor manufacturing apparatus provided with a high-purity silicon carbide sintered body layer having an average particle size of 30 μm or less.

[0010] According to a second aspect of the present invention, in the first aspect, the thickness of the sintered body layer is 100 µm or more. According to a third aspect of the present invention, there is provided a component for use in a semiconductor manufacturing apparatus utilizing plasma, wherein the component for a semiconductor manufacturing apparatus comprising a high-purity silicon carbide sintered body having an average crystal grain size of 30 μm or less. This is the gist.

[0011] The invention according to claim 4 is the invention according to claims 1 to 3.
In any one of the sintered body layer, the bulk density of the sintered body was to be ^{2.5g / cm 3 ~2.9g / cm 3} .

Hereinafter, the "action" of the present invention will be described. According to the first to third aspects of the present invention, since the average particle size of the crystal particles is smaller than 30 μm or less as compared with the conventional one, the abundance ratio in the sintered body of the large crystal particles that may fall off is also extremely small. Has become. Therefore, even if the sintered body or the sintered body layer is exposed to the plasma, a situation such as dropping of crystal particles from the surface layer is less likely to occur than before.
That is, the consumption of the surface layer due to the plasma irradiation is reduced, and the generation of particles is suppressed. As a result, it is possible to provide a component that can be used stably for a long time without worrying about contamination of the semiconductor wafer.

According to the second aspect of the present invention, in addition to the excellent durability of the sintered body layer itself, 100%
The thickness of about 2 μm or more, which is about twice or more of the conventional thickness, is secured. Therefore, a situation such as dropping of crystal particles from the surface layer due to plasma irradiation is less likely to occur than in the past. Therefore, it does not occur that the sintered body layer is consumed in a short time and the base material is exposed therefrom.

According to the present invention, the bulk density of the sintered body layer or the sintered body is 2.5 g / cm ^{3 to} 2.9 g / cm ² .
cm ³ . Therefore, high thermal conductivity and plasma resistance can be achieved while avoiding an increase in impurity concentration.

That is, if the bulk density is too low, the sintered body layer or the sintered body will not be dense due to the increase in pores, so that not only a high thermal conductivity cannot be achieved but also the plasma resistance will be poor. Because it becomes. If the bulk density is too high, the sintered body layer and the sintered body become dense, so that there is no particular problem regarding the thermal conductivity and the plasma resistance.
However, in order to realize a high bulk density, it is necessary to add a large amount of an auxiliary agent for promoting the growth of crystal particles to the raw material powder. As a result, the impurity concentration in the obtained sintered body layer or sintered body increases, which may cause contamination of the semiconductor wafer.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a plasma etching apparatus 1 according to an embodiment of the present invention will be described in detail with reference to FIGS.

The plasma etching apparatus 1 of the present embodiment shown in FIG. 1 is a kind of a semiconductor manufacturing apparatus using plasma. This apparatus 1 exposes a silicon surface by exposing a silicon wafer 2 that has undergone an exposure and development process to a gas plasma P1 to selectively remove only a photosensitive region in a photosensitive film. Plasma etching equipment 1
Are various components (chamber 3, electrode plates 4, 5,
It comprises a support ring 6, a stage 7, and a dummy ring 8).

The chamber 3 is a cylindrical part, and its inside is hollow. A discharge port 3a for discharging the gas plasma P1 by evacuation is formed on the side surface of the chamber 3. In the chamber 3, an upper electrode plate 4 as a positive electrode and a lower electrode plate 5 as a negative electrode are provided.
Each pair is arranged in a state of being vertically separated from each other.

The upper electrode plate 4 is a disc-shaped part made of a conductive material, and has a large number of through holes 4a in the center thereof.
Are formed. The gas plasma P1 is supplied into the chamber 3 through these through holes 4a. Support ring 6 which is a ring-shaped part
Is fixed to the upper inner peripheral surface of the chamber 3. The outer periphery of the bottom surface of the upper electrode plate 4 is supported on the upper surface of the support ring 6 over the entire periphery. That is, the upper electrode plate 4 is indirectly attached to the inner wall surface of the chamber 3 via the support ring 6.

The stage 7 is disposed at the lower center in the chamber 3. The lower electrode plate 5 is a component made of a disc-shaped conductive material, and has a circular convex portion 9 at the center of the upper surface. The outer dimensions of the projection 9 are designed to be slightly smaller than the outer dimensions of the silicon wafer 2. The lower electrode plate 5 is supported on the stage 7.

As shown in FIG. 1, a component called a dummy ring 8 is arranged on the outer peripheral portion of the upper surface of the lower electrode plate 5. The dummy ring 8 supports the outer peripheral portion of the bottom surface of the silicon wafer 2 over its entire circumference, and can be moved vertically within a predetermined range by a driving mechanism (not shown). That is, by changing the distance from the upper electrode plate 4 to the silicon wafer 2, the irradiation condition of the gas plasma P1 can be appropriately adjusted.

As shown in FIGS. 1 and 2, the dummy ring 8 has a ring shape, and a fitting recess 10 for holding the silicon wafer 2 is provided at the center thereof. The depth of the fitting concave portion 10 is larger than the thickness of the silicon wafer 2. A through hole 11 having a circular cross section is formed on the bottom surface of the fitting recess 10. The inner diameter of the through hole 11 is designed to be substantially equal to the outer diameter of the projection 9 of the lower electrode plate 5. Therefore, when the dummy ring 8 is at the lowest position, the protrusion 9 is
1 and the upper surface of the projection 9 and the engagement recess 10
The height is almost the same as the bottom surface. On the lower surface side of the dummy ring 8, there is a circumferential stepped portion 12.

Here, each surface S1 of the dummy ring 8
~ S8 is defined as follows. S1: a region on the upper surface of the dummy ring 8 which is on the outer peripheral side of the fitting concave portion 10, S
2: inner surface of fitting recess 10, S3: bottom surface of fitting recess 10, S4: inner wall surface of through hole 11, S5: dummy ring 8
Area on the inner peripheral side of the step 12 on the lower surface of S
6: a vertical surface of the step portion 12, S7: a region on the lower surface of the dummy ring 8 that is closer to the outer periphery than the step portion 12,
S8: The outer peripheral surface of the dummy ring 8. Among these, the surface that is relatively often exposed to the gas plasma P1 is:
The surfaces S1, S2, S3, S6, S7 and S8 are located at the position where the surface S1 is most likely to be exposed to the gas plasma P1. That is, the surface S1 is located at the top of the dummy ring 8 and faces the flow of the gas plasma P1 directly.

The dummy ring 8 of this embodiment is a dense body made of a high-purity silicon carbide (SiC) sintered body. “High purity” means that the concentration of impurities (mainly sintering aid) in silicon carbide is 5 ppm or less.

The average particle size of the crystal particles of the carbon silicon sintered body is 3
It must be 0 μm or less, preferably 25 μm or less, and more preferably 20 μm or less. The reason is that with such a setting, the abundance ratio of large crystal particles (crystal particles having a size of 50 μm or more) which may fall off in the sintered body can be made extremely small (in some cases, none). Therefore, a situation such as dropping of crystal grains from the surface layer of the dummy ring 8 is less likely to occur than before.

The bulk density of the silicon carbide sintered body is 2.5 g / c
m ³ ~2.9g / cm ^3, and further 2.6g / cm ³ ~
It is preferably 2.8 g / cm ³ . The reason is,
As described above.

It is desirable that the silicon carbide sintered body is impregnated with metallic silicon. This is because pores are closed by performing such impregnation, so that a dense sintered body can be obtained relatively easily. In addition, the impregnation rate of the metallic silicon when performing the impregnation is 20% or more, further 30% or more
In particular, it is preferably 35% or more.

Dummy ring 8 made of a silicon carbide sintered body as described above can be manufactured by the following procedure. First, a silicon carbide sintered body is produced through a forming and firing process. The sintered body obtained as described above is used as a base material, and a grinding process such as drilling or lapping is performed on the base material. As a result, a dummy ring 8 having a desired shape is completed.

[0029]

EXAMPLES and COMPARATIVE EXAMPLES In this embodiment, a dummy ring 8 made of a silicon carbide sintered body (manufactured by IBIDEN Co., Ltd., trade name: SCH-07) having the basic physical properties shown in the table of FIG. It was fabricated and used as an example. Specifically, the following procedure was adopted.

A mixture of α-type crystal silicon carbide powder (manufactured by Shinano Electric Smelting Co., Ltd., trade name: GC # 6000) and β-type crystal silicon carbide powder (manufactured by IBIDEN Co., Ltd.) in an amount of 50% by weight was used. Raw material powder was used. For 100 parts by weight of this,
After blending 5 parts by weight of polyvinyl alcohol and 300 parts by weight of water, the mixture was mixed in a ball mill for 5 hours or more to obtain a uniform mixture. After drying the mixture for a predetermined time to remove a certain amount of water, an appropriate amount of the dried mixture was collected and granulated. Then, the obtained granules of the mixture were filled in a mold and pressurized to produce a disk-shaped formed body.

The formed body was placed in a graphite crucible capable of shutting off outside air, and was fired using a tanman firing furnace. The firing was performed in an argon gas atmosphere at 1 atm. Further, at the time of firing, the material was heated up to the maximum temperature of 2000 ° C., and thereafter kept at a predetermined temperature. As a result, a disc-shaped high-purity sintered silicon carbide having an average crystal grain size of 30 μm or less was obtained.

The disc-shaped silicon carbide sintered body was subjected to an inner peripheral penetration process, an inner peripheral roughing process, an outer peripheral process, an inner peripheral boring process, an outer peripheral stepping process, and a thickness finishing process.
In addition, three types of dummy rings 8 made of sintered bodies having the basic physical properties as shown in the same table were separately manufactured, and these were used as Comparative Examples 1, 2, and 3. The average particle size of the crystal particles of the sintered bodies of these comparative examples is 50 μm or more.

In order to judge the quality of the above four types of samples, the following comparative tests were carried out. The gas plasma P1 is irradiated to the four kinds of test samples under predetermined conditions, and the consumption amount (μm) of the surface layer on the surface S1 in the sintered body
FIG. 4 shows the results obtained when the measured values were obtained after a certain period of time (after 22.5 hours, 60.0 hours, and 82.5 hours). The plasma irradiation conditions at that time are also shown in FIG. According to that, in each sample,
As the plasma irradiation time became longer, the amount of consumption tended to increase. However, it was clarified that the samples of the examples generally consumed less than the samples of Comparative Examples 1 to 3.

Further, with respect to the three test samples except Comparative Example 3, the surface roughness Rmax, Rmax
The results of measuring the time-dependent changes of a and Rz (μm) are shown in the graph of FIG. According to the results, in any of the samples, there was a tendency that the longer the plasma irradiation time, the higher the surface roughness. However, compared to the samples of Comparative Examples 1 and 2, the sample of the example tended to converge the increase in surface roughness earlier. Also, it was easily predicted that the convergence value of the surface roughness was smaller in the example than in the comparative examples 1 and 2.

Further, in Example and Comparative Example 2,
After performing a nitric acid treatment for 3 hours in advance, the surface morphology was observed by SEM or the like. The photograph of FIG. 6 (a) shows the sample of the example (in a state where plasma was not irradiated) by 200.
It is twice as large. The SEM photograph of FIG.
The sample is enlarged 2000 times. FIG.
The photograph in (a) is a 200-fold magnification of the sample of Comparative Example 2 (in a state not irradiated with plasma). FIG.
The SEM photograph of (b) is an enlargement of the same sample 2000 times.

As is clear from these photographs, the sample of the example had smaller crystal grains overall than the sample of the comparative example 2. In the example, the maximum particle size was about 30 μm to 40 μm at most, whereas in Comparative Example 2, the maximum particle size was 100 μm to 150 μm.
Some were as large as μm. In addition, the extremely large crystal grains present in the comparative example were square and plate-shaped.

Further, after the plasma irradiation for a predetermined time was performed on the example and the comparative example 2, the same surface morphology was observed with a SEM (SEM photographs are omitted). According to the result, in Comparative Example 2, a portion where large crystal grains of 100 μm or more fell off was seen in a small number, and a large gouge hole was generated there. On the other hand, in the example, the existence of such a gouge was not recognized at all. This is considered to be because the existence ratio of the large crystal particles that may fall off in the sintered body is extremely small in the example, and this has brought about a good result.

Then, when the results thus far are combined, it is concluded that the sample of the example has overall superior characteristics as compared with the comparative examples. Therefore, according to the present embodiment, the following effects can be obtained.

(1) The dummy ring 8 used in the plasma etching apparatus 1 has an average crystal grain diameter of 30 μm.
It is made of the following high-purity silicon carbide sintered body. Therefore, the consumption of the surface layer due to the plasma irradiation is reduced, and the generation of particles is suppressed. As a result, the dummy ring 8 can be stably used for a long time without worrying that the silicon wafer 2 is contaminated.

(2) The bulk density of the silicon carbide sintered body forming the dummy ring 8 is 2.5 g / cm ^{3 to} 2.9 g / c.
m ³ is set in a suitable range. Therefore, high thermal conductivity and plasma resistance can be achieved while avoiding an increase in impurity concentration. Therefore, the dummy ring 8 can be used more stably for a longer period of time.

The embodiment of the present invention may be modified as follows. -You may comprise like the dummy ring 8A of another example shown in FIG. That is, here, the entire surface S1 of the base material 15 (including, for example, materials other than silicon carbide such as carbon).
To S8 are covered with a high-purity sintered silicon carbide layer 16. The high-purity silicon carbide sintered body layer 16 may be, for example, of the same type as that described in the embodiment as an example (see the table in FIG. 3). In this case, thickness t1 of silicon carbide sintered body layer 16 is preferably set to at least 100 μm or more.

Another example of the dummy ring 8 shown in FIG.
B, some surfaces of the substrate 15 (for example, S1 to S3
, S6 to S8) may be adopted in which only the sintered body layer 16 is covered. Accordingly, in FIG. 2, the surfaces S4 and S5 of the substrate 15 are exposed to the outside. However, in adopting such a configuration, the gas plasma P1
It is desirable to coat S1, which is the surface most liable to be exposed.

The components of the plasma etching apparatus 1 other than the dummy ring 8, that is, the chamber 3,
The electrode plates 4 and 5, the support ring 6, and the stage 7 may be manufactured using the same sintered body as in the embodiment. Further, as described above as another example, it is of course allowable to form the sintered body layer 16 on the entire surface or a part of the parts 3 to 7.

The present invention provides a plasma etching apparatus 1
The present invention can be applied to components other than those, for example, components in a plasma ashing apparatus, a plasma CVD apparatus, and the like. Here, as specific examples of the components of the plasma CVD apparatus, a susceptor, a pickup,
There are a dummy wafer, an insulating cover, and the like.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments will be listed below together with their effects. (1) The method according to any one of claims 1 to 4, wherein a maximum particle size of the crystal grains is 100 μm or less (preferably 50 μm or less).
μm or less). Therefore, according to the invention described in the technical idea 1, the abundance ratio of large crystal particles which may fall off in the sintered body decreases.

(2) In any one of the first to fourth aspects and the technical idea 1, the impurity concentration in the sintered body layer and the sintered body is 5 ppm or less. Therefore, according to the invention described in the technical idea 2, since the sintered body has a high purity, the semiconductor wafer is less likely to be contaminated.

(3) Claims 1 to 4, technical idea 1,
2. In any one of 2., the sintered body layer and the sintered body are made of silicon carbide impregnated with metallic silicon. Therefore, according to the invention described in the technical idea 3,
A dense sintered body can be obtained relatively easily.

(4) In the technical idea 3, the metal silicon impregnation rate is 20% or more. (5) In any one of claims 1 to 4 and technical ideas 1 to 4, the semiconductor manufacturing apparatus using the plasma is a plasma etching apparatus, a plasma ashing apparatus, a plasma CVD apparatus, or the like.

(6) In any one of claims 1 to 4, and technical ideas 1 to 5, the component for a semiconductor manufacturing apparatus has a surface exposed to plasma when the apparatus is used.

[0050]

As described above in detail, according to the first to fourth aspects of the present invention, there is provided a component for a semiconductor manufacturing apparatus which can be stably used for a long time without worrying about contamination of a semiconductor wafer. Can be provided.

According to the second aspect of the present invention, it is ensured that the sintered body layer is consumed in a short time and the base material is not exposed therefrom. According to the fourth aspect of the present invention, high thermal conductivity and plasma resistance can be achieved while avoiding an increase in impurity concentration, so that the device can be used more stably for a longer period of time.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a main part of a plasma etching apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a dummy ring and a silicon wafer.

FIG. 3 is a table showing basic physical characteristics of sintered bodies of an example and comparative examples.

FIG. 4 is a graph showing changes in the amount of wear of the surface layer due to plasma irradiation for the sintered bodies of the examples and comparative examples.

FIG. 5 is a graph showing how the surface roughness changes due to plasma irradiation for the sintered bodies of the examples and comparative examples.

FIGS. 6A and 6B are micrographs of a sintered body of an example.

7A and 7B are micrographs of the sintered body of Comparative Example 2. FIG.

FIG. 8 is a partial schematic sectional view showing another example.

FIG. 9 is a partial schematic sectional view showing another example.

[Explanation of symbols]

1 .... Plasma etching device as semiconductor manufacturing device,
3. Chamber as a part for semiconductor manufacturing equipment, 4, 5,.
Electrode plate as part for semiconductor manufacturing equipment, 6 ... Support ring as part for semiconductor manufacturing equipment, 7 ... Stage as part for semiconductor manufacturing equipment, 8, 8A, 8B ... Dummy ring as part for semiconductor manufacturing equipment, 16 ... High-purity silicon carbide sintered body layer, t1 ... Thickness of sintered body layer.

Continued on front page F-term (reference) 4G001 BA22 BA71 BB22 BB71 BD03 BD38 BE22 BE32 BE33 5F031 CA02 CA11 DA13 EA01 HA25 MA23 MA28 MA32 PA26

Claims (4)

[Claims] 1. A component used in a semiconductor manufacturing apparatus utilizing plasma, comprising at least a high-purity silicon carbide sintered body layer having an average crystal grain size of 30 μm or less on its surface. Parts. 2. The component for a semiconductor manufacturing apparatus according to claim 1, wherein said sintered body layer has a thickness of 100 μm or more. 3. A component for use in a semiconductor manufacturing apparatus utilizing plasma, wherein the component is a high-purity silicon carbide sintered body having an average crystal grain diameter of 30 μm or less. Wherein said sintered body layer, the bulk density of the sintered body in any one of claims 1 to 3, characterized in that it is 2.5g / cm ³ ~2.9g / cm ³ A part for semiconductor manufacturing equipment according to the above.