JP2000243812A - Clamp ring for semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it hard to shave a semiconductor wafer and to make it hard to generate particles in a clamp ring by a method wherein the clamp ring is composed of a ceramic sintered body and the surface roughness of the wafer holding part, of the ring is set lower than a prescribed value. SOLUTION: A clamp ring consists of a ceramic sintered body and has a holding part for holding the peripheral edge part of a semiconductor wafer, such as a silicon wafer. The surface roughness of at least the part, which comes into contact with the wafer, of the holding part is set lower than Ra = shorter than 10 μm. By constituting the clamp ring using the ceramic sintered body, the problem of such a corrosion as that in a quartz glass is hardly generated. The clamp ring 1 is provided with a ring-shaped main body 2 and the holding part 3, which is protuberantly provided from the main body 2 to its inside and holds the semiconductor wafer 4 on a stage 5, the part 3 has a contact part 3a coming into contact with the wafer 4 and the surface roughness of this part 3 is set lower than a prescribed value. Thereby, the wafer is hardly shaved and particles are hardly generated in the clamp ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer clamp ring for holding a semiconductor wafer when performing various plasma processes and the like by a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, there are steps such as etching and film formation, which use a plasma of a corrosive gas such as CF ₄ or Cl ₂ . As one of the members used in the semiconductor manufacturing apparatus for performing these steps, there is a clamp ring for holding a peripheral portion of a semiconductor wafer on a stage. The clamp ring holds the semiconductor wafer on the stage by directly pressing the periphery of the semiconductor wafer.

[0003] As such a member, quartz glass has conventionally been used frequently because a high-purity member can be obtained and the metal in the constituent elements is Si and does not contaminate the chamber. However, since quartz glass is significantly corroded by plasma, the frequency of replacement is high, and it is necessary to frequently stop the apparatus, which causes a reduction in device production efficiency.

In order to solve such inconvenience, a sintered alumina body is used as a clamp ring instead of quartz glass. Since the alumina sintered body has better corrosion resistance than quartz glass, the frequency of replacement can be reduced.

[0005]

However, since the clamp ring comes into direct contact with the semiconductor wafer, there is a disadvantage that the clamp ring cuts the wafer and causes particles.

The present invention has been made in view of such circumstances, and has as its object to provide a semiconductor wafer clamp ring capable of suppressing generation of particles.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the clamp ring is made of a ceramic sintered body, and the surface roughness of a holding portion for holding a semiconductor wafer. It is found that the semiconductor wafer is less likely to be scraped and particles are less likely to be generated when the value is less than or equal to a predetermined value.

The present invention has been made based on such knowledge, and the first invention has a holding portion made of a ceramic sintered body and holding a peripheral portion of a semiconductor wafer. Provided is a semiconductor wafer clamp ring, wherein the surface roughness of a portion in contact with the semiconductor wafer is Ra = 10 μm or less.

According to a second aspect of the present invention, there is provided the clamp ring for a semiconductor wafer according to the first aspect of the present invention, wherein the clamp ring comprises a ceramic sintered body containing at least one of a rare earth oxide and aluminum oxide. .

A third aspect of the present invention is the clamp ring according to the first or second aspect, wherein the holding portion is provided so as to protrude inward from the ring-shaped main body, and has a protruding length of 1.5 to 6 mm. And a clamp ring for a semiconductor wafer characterized in that a radius of curvature R at a tip portion thereof is 0.2 mm or more.

According to the present invention, when the clamp ring comes into contact, the generation of particles due to the shaving of the semiconductor wafer can be suppressed, so that the apparatus can be continuously operated and the production efficiency is improved. Can be.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. The clamp ring of the present invention is made of a ceramic sintered body, has a holding portion for holding a peripheral portion of a semiconductor wafer such as a silicon wafer, and at least a surface roughness of a portion of the holding portion that contacts the semiconductor wafer is Ra = It is 10 μm or less.

When the clamp ring is made of a ceramic sintered body, the problem of corrosion such as quartz glass hardly occurs. In addition, since the holding portion directly contacts the surface (polished surface) of the semiconductor wafer and holds the wafer by applying a load, the surface roughness of at least a portion of the holding portion that comes into contact with the semiconductor wafer should be Ra = 10 μm or less. Accordingly, when the clamp ring comes into contact with the semiconductor wafer, the semiconductor wafer is hardly shaved and particles are less likely to be generated. If the Ra of the portion exceeds 10 μm, the semiconductor wafer is easily damaged when it comes into contact, and it is likely to cause particles.

The ceramic sintered body constituting the clamp ring is not particularly limited as long as it has higher corrosion resistance than quartz glass, but preferably contains at least one of a rare earth oxide and aluminum oxide.
Thereby, excellent corrosion resistance can be obtained, and generation of particles can be more effectively prevented. In particular,
Rather than using a rare earth oxide and aluminum oxide alone, it is possible to further increase the corrosion resistance by compounding them.

It is preferable to use yttrium oxide as the rare earth oxide. By compounding yttrium oxide and aluminum oxide, yttrium oxide-
An aluminum oxide compound or a mixture thereof is formed. These compounds have extremely high corrosion resistance to the plasma of the corrosive gas, so that by forming a clamp ring, extremely excellent corrosion resistance is realized. Note that the yttrium oxide-aluminum oxide compounds include YAlO ₃ , Y ₄ Al ₂ O ₉ , and Y ₃ Al ₅ O.
₁₂ (yttrium-aluminum-garnet) and the like.

The holding portion is provided so as to protrude inward from the ring-shaped main body, and has a protruding length of 1.5 to 6 mm and a radius of curvature R of a tip portion of 0.2 mm or more. It is preferred that

If the length of the projection of the holding portion is shorter than 1.5 mm, the contact area between the projection portion and the wafer becomes small, so that the wafer holding becomes incomplete. If it is longer than 6 mm, the strength of the holding portion becomes insufficient, and there is a possibility that cracking, chipping or the like may occur. If the radius of curvature R at the tip of the holding portion is smaller than 0.2 mm, the semiconductor wafer may be damaged, which may cause particles.

Next, a clamp ring according to an embodiment will be described with reference to FIGS. FIG. 1 is a plan view and a sectional view of the clamp ring, and FIG. 2 is an enlarged sectional view showing a main part of the clamp ring of FIG. The clamp ring 1 is made of a ceramic sintered body, and includes a ring-shaped main body 2 and a holding portion 3 provided to protrude inward from the main body 2 and holding the semiconductor wafer 4 on the stage 5. As shown in FIG.
The contact portion 3a has a surface roughness Ra of 10 μm or less. Also, the holding unit 3
Has a protruding length L of 1.5 to 6 mm, and has a tip 3
It is preferable that the radius of curvature R of b is 0.2 mm or more.

In such a clamp ring 1, as shown in FIG. 2, the contact portion 3 a of the holding portion 3 contacts the surface of the semiconductor wafer 4 and applies a load to the semiconductor wafer 4 to hold the semiconductor wafer 4. I do. In this case, as described above, at least the contact portion 3a of the holding portion 3 is
By setting the surface roughness to be equal to or less than m, particles can be hardly generated.

[0020]

Embodiments of the present invention will be described below. (First Embodiment) Here, yttrium-aluminum is used as a ceramic sintered body constituting a clamp ring.
Garnet and aluminum oxide (alumina) were used.

The yttrium-aluminum-garnet sintered body was manufactured as follows. First, the yttrium oxide powder and the aluminum oxide powder were put into a polyethylene pot together with ion-exchanged water, an organic dispersant, an organic binder, and a nylon ball containing an iron core, and mixed for 24 hours. Next, the obtained slurry was dried with a spray drier to produce granules. The granules were subjected to CIP molding and green processing to form a clamp ring shape, and then fired in an atmospheric furnace.

The alumina sintered body was manufactured as follows. First, aluminum oxide powder was put into a polyethylene pot together with ion-exchanged water, an organic dispersant, an organic binder, and a nylon ball containing an iron core, and mixed for 24 hours. Next, the obtained slurry was dried with a spray drier to produce granules. The granules were subjected to CIP molding and green processing to form a clamp ring shape, and then fired in an atmospheric furnace.

A predetermined finishing process is performed on these sintered bodies. A clamp ring was manufactured in which the surface roughness of the portion of the holding portion that contacts the semiconductor wafer was variously changed. The length L of the protrusion of the holder is 4 mm, and the radius of curvature R of the tip of the holder is R.
Is 0.4 mm. The clamp ring manufactured in this manner was incorporated into a chamber of a parallel plate type RIE etching apparatus, plasma of CF ₄ + O ₂ etching gas was generated, and continuous operation was performed for 1500 hours to measure the number of particles on the wafer. . Table 1 shows the results.

[0024]

[Table 1]

As shown in Table 1, any of the sintered bodies using the clamp ring had a surface roughness Ra of 10 μm.
m or less, the number of particles was small even at an operation time of 1500 hours. On the other hand, the surface roughness Ra is 10 μm.
In all of the cases exceeding m, the number of particles increased. From this, it was confirmed that particles can be reduced by using a ceramic sintered body as the clamp ring and setting the surface roughness Ra of the portion in contact with the semiconductor wafer to 10 μm or less.

When yttrium-aluminum-garnet (YAG) was used as the ceramic sintered body, particles were particularly reduced because of high corrosion resistance.

(Second Embodiment) Here, the surface roughness Ra
Was set to 10 μm or less, the presence or absence of abnormalities such as the number of particles and chipping of the clamp ring was confirmed by variously changing the protrusion length L of the holding portion and the radius of curvature R of the tip portion of the holding portion. Table 2 shows the results.

[0028]

[Table 2]

When the projection length L exceeded 6 mm, the number of particles was small, but some of the holding portions were chipped. When the protrusion length L is less than 1.5 mm,
Although not shown in the table, insufficient clamping sometimes occurred. On the other hand, when the protruding length L is in the range of 1.5 to 6 mm, such a problem does not occur. In addition, when the radius of curvature R of the tip portion of the holding portion is less than 0.2 mm,
It was confirmed that the generation of particles was slightly increased as compared with the case of 0.2 mm or more. From this, it has been confirmed that the protruding length L of the holding portion is preferably 1.5 to 6 mm, and the radius of curvature R of the tip portion is preferably 0.2 mm or more.

[0030]

As described above, according to the present invention,
The number of particles generated when the device is operated continuously for a long time can be reduced. Therefore, the number of stoppages of the apparatus can be reduced, and the production efficiency of semiconductor devices can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view illustrating a clamp ring for a semiconductor wafer according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of the clamp ring of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1; Clamp ring 2; Main body 3; Holding part 3a; Contact part 3b; Tip part 4: Semiconductor wafer 5;

Continuing from the front page (72) Inventor Hiromichi Otaki 3-5-Meiji, Izumi-ku, Sendai City, Miyagi Prefecture Inside the Japan Ceratech headquarters and factory (72) Inventor Yukio Kishi 3-5-Memori, Izumi-ku, Sendai-shi, Miyagi Prefecture (72) Inventor Naomizu Odano 1-2-3 Kiyosumi, Koto-ku, Tokyo Inside the Research Institute of Pacific Cement Co., Ltd. (72) Inventor Daiki Suzuki 1-2-2 Kiyosumi, Koto-ku, Tokyo No. 23 Taiheiyo Cement Co., Ltd. Research Headquarters (72) Eiji Fukuda Inventor 1-2-2 Kiyosumi, Koto-ku, Tokyo Tokyo 23 Cement Co., Ltd. Research Headquarters (72) Inventor Chiharu Wada 1-2-2 Kiyosumi, Koto-ku, Tokyo No. 23 Taiheiyo Cement Co., Ltd. Research Division F-term (reference) 5F031 CA02 HA25 HA28 MA28 MA32 PA26

Claims (3)

[Claims] 1. A semiconductor sintered body having a holding portion for holding a peripheral portion of a semiconductor wafer, wherein a surface roughness of at least a portion of the holding portion that is in contact with the semiconductor wafer is Ra.
= 10 μm or less, a clamp ring for a semiconductor wafer. 2. The clamp ring for a semiconductor wafer according to claim 1, comprising a ceramic sintered body containing at least one of a rare earth oxide and aluminum oxide. 3. The holding portion is provided so as to protrude inward from a ring-shaped main body, has a protruding length of 1.5 to 6 mm, and has a curvature radius R of a tip portion of 0.2 mm or more. The clamp ring for a semiconductor wafer according to claim 1 or claim 2, wherein