JP2002075962A - Glassy carbon-graphite composite ring for mounting silicon wafer and dry etching system comprising it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite ring for mounting a silicon wafer in which the trend of increasing diameter of silicon wafer can be dealt with, contamination with impurities is prevented while using an inexpensive material, thermal strain is prevented by enhancing the cooling efficiency and the yield of silicon wafer is enhanced, and to provide a dry etching system comprising it. SOLUTION: The composite ring member for mounting a silicon wafer comprises a first tubular ring having a receiving part for mounting a silicon wafer on the surface and a second tubular ring bonded to the rear surface thereof wherein (a) the first tubular ring is made of glassy carbon and the second tubular ring is made of graphite entirely coated with glassy carbon, (b) at least one of the first or second tubular ring is provided, on the bonding face thereof, with a liquid reservoir having a volume sufficient for preventing projection of adhesive from the bonding face while sustaining adhesion strength, and (c) the first or second tubular rings are bonded rigidly by carbon based adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glassy carbon-graphite composite ring for mounting a silicon wafer used in the manufacture of a semiconductor device and a dry etching apparatus equipped with the same, and more particularly to an inexpensive material using the same. In addition, the present invention relates to a glass-like carbon-graphite composite ring for mounting on a silicon wafer and a dry etching apparatus equipped with the same, which prevents impurity contamination, has a high cooling efficiency, does not cause thermal distortion, and improves the yield of the silicon wafer.

[0002]

2. Description of the Related Art With the development of information devices typified by computers, there has been a strong demand for semiconductor integrated circuits, which are the main components of such devices, to have higher integration. In manufacturing a semiconductor device, impurities are extremely disliked not only in the raw material but also in the manufacturing process from the viewpoint of ensuring performance, so that the operation is performed in a clean environment such as a clean room. Needless to say, it is necessary that each member constituting the manufacturing apparatus does not generate impurities. Ion implantation, dry etching,
Wafer processing represented by sputtering is performed in a reaction chamber that can be decompressed to a high vacuum called a chamber, but as the degree of integration of semiconductor integrated circuits increases, it is necessary to meet higher purity standards. Therefore, the chamber and each member constituting the chamber are also required to have material characteristics with less impurity contamination.

[0003] Each member inside the chamber will be described with reference to FIG. 3 taking the case of dry etching as an example. Generally, a pair of electrodes consisting of an upper electrode and a lower electrode are installed in the chamber in opposition to each other. By connecting the lower electrode to a high-frequency power supply, plasma is generated between the opposing electrodes. The silicon wafer is mounted directly above the lower electrode via a mounting member, and is etched by an etching gas in a plasma atmosphere.

Conventionally, a single cylindrical ring made of silicon having a receiving portion on the surface of which a silicon wafer can be mounted has been used as a wafer mounting member in a dry etching apparatus. Although it is experimental, since it is too brittle, the composite ring consisting of a cylindrical ring made of silicon and a cylindrical ring made of metal or metal oxide such as aluminum supported to reinforce it Rings are starting to be used.

[0005] However, in such a composite ring of silicon and a metal or metal oxide such as aluminum, not only there is a risk of impurity contamination generated from the metal or metal oxide such as aluminum, but also the composite ring itself has a low cooling efficiency. Inferior, it is not possible to increase the processing speed of etching, and furthermore, since the difference in thermal expansion between silicon and a metal or metal oxide such as aluminum is large, thermal distortion occurs, resulting in poor positional stability of the silicon wafer. However, the processing density of the etching cannot be made uniform, and as a result, there is a problem that the yield of semiconductor devices in dry etching, that is, the yield of silicon wafers is deteriorated. In addition,
Large (large-diameter) silicon wafers have been required for large-diameter silicon wafers, but conventional silicon large (large-diameter) single cylindrical rings have been required. Then, there is a problem that silicon becomes a cast product (polycrystalline silicon) and the material cost becomes extremely high.

In order to solve the problems of the conventional single cylindrical ring made of silicon and the complex ring, the present applicant has filed Japanese Patent Application No. 2000-156064, which was filed earlier, with silicon and graphite. Was proposed, but this silicon-graphite composite ring,
Although functionally satisfactory, the use of expensive silicon as an indispensable member presents a cost problem.As an alternative, the silicon-graphite composite ring proposed earlier was used. There has been a demand for a composite ring which has the same level of function, uses less expensive materials, and can cope with a large diameter silicon wafer.

Under the circumstances described above, various members for a wafer processing apparatus in a semiconductor manufacturing apparatus have been conventionally proposed, for example, Japanese Patent Application Laid-Open No. 10-25617.
No. 7 proposes a member for a wafer processing apparatus in which glassy carbon having a specific thickness is adhered to the surface of a metal member or a graphite member which is irradiated with an ion beam or the like.

However, in spite of these proposals, the above-mentioned drawbacks have been eliminated, that is, it is possible to cope with an increase in the diameter of a silicon wafer, to prevent impurity contamination while using an inexpensive material, and to reduce the cooling efficiency. There is no device member for mounting a silicon wafer, which does not cause thermal distortion and improves the yield of the silicon wafer. Therefore, in a wafer mounting apparatus, there has been a strong demand for the development of a wafer mounting member capable of improving the yield of semiconductor devices.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the above-described conventional single cylindrical ring and composite ring, and to use an inexpensive material which can cope with a large diameter silicon wafer. It is an object of the present invention to provide a composite ring for mounting a silicon wafer and a dry etching apparatus equipped with the same, whereby impurity contamination is prevented, cooling efficiency is high, thermal distortion does not occur, and the yield of the silicon wafer is improved.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies on the development of an optimal silicon wafer mounting member. By forming a composite of a first cylindrical ring formed of glassy carbon having a receiving portion capable of mounting a wafer and a second cylindrical ring formed of graphite bonded to the back surface thereof, Glass-like carbon for silicon wafer mounting that can cope with the large diameter of silicon, is less expensive than silicon, can prevent impurity contamination, can maintain good wafer position stability, and can improve the yield of semiconductor devices. It has been found that a graphite composite ring and a dry etching apparatus equipped with the same can be obtained. Further, in joining the glassy carbon member of the first tubular ring and the graphite member of the second tubular ring,
It has been found that the adhesive often protrudes and the repair work is complicated, but it can be solved by providing a liquid reservoir for preventing the adhesive from protruding, for example, a groove at the joint. The present invention has been completed based on these findings.

That is, according to the first aspect of the present invention,
A composite ring member for mounting a silicon wafer, comprising: a first cylindrical ring having a receiving portion capable of mounting a silicon wafer on a front surface thereof; and a second cylindrical ring joined to the back surface thereof, wherein Is formed of glassy carbon, while the second cylindrical ring is formed of graphite coated on its entire surface with glassy carbon, and (b) the first cylindrical ring or the second cylindrical ring. At least one of the cylindrical rings has a liquid reservoir on its joint surface with a volume sufficient to prevent the adhesive from protruding from the joint surface while maintaining the adhesive strength. A composite ring member for mounting a silicon wafer is provided in which the cylindrical ring and the second cylindrical ring are firmly joined by a carbon-based adhesive.

According to the second aspect of the present invention, the first aspect is provided.
Further, (d) at least one of the first cylindrical ring and the second cylindrical ring is provided on at least one of the joining surfaces so that the joining area between the first and second tubular rings increases and the two can fit together. A composite ring member for mounting a silicon wafer is provided, wherein one convex engagement portion and the same number of concave engagement portions are provided on the other joint surface.

Further, according to the third and fourth aspects of the present invention, the carbon-based adhesive is added to the polycarbodiimide resin.
The composite ring for mounting on a silicon wafer according to any one of the above, wherein the adhesive is an adhesive mixed with a conductive powder filler, or the conductive powder filler is graphite powder. A member is provided.

According to a fifth aspect of the present invention, in the second cylindrical ring, the thickness of the glassy carbon coat layer is at least 2-3 μm. 2. A composite ring member for mounting a silicon wafer according to the item 1.

Further, according to a sixth aspect of the present invention, there is provided a dry etching apparatus equipped with the above-described composite ring member for mounting a silicon wafer according to any one of the first to fifth aspects.

As described above, the present invention provides a silicon wafer which can prevent impurity contamination, has a good cooling efficiency, does not generate thermal distortion, and can improve the yield of the silicon wafer while using a material less expensive than silicon. The present invention relates to a glassy carbon-graphite composite ring for mounting and a dry etching apparatus equipped with the ring.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. 1. First Cylindrical Ring A glassy carbon-graphite composite ring is used as the silicon wafer mounting member of the present invention, and the first cylindrical ring on which the silicon wafer is directly mounted, that is, the glassy carbon is used as a clamp ring. (Sometimes referred to as a glassy carbon ring) is used. In particular, glassy carbon rings
It is used in the etching process to fix the silicon wafer, to protect the outer edge of the wafer, and especially to prevent contamination.

In order to be used as a clamp ring for a silicon wafer, the first cylindrical ring formed of glassy carbon has a receiving portion on the surface of which a silicon wafer can be mounted. There is no particular limitation as long as the silicon wafer can be stably fixed in the etching step, but it is usually a cylindrical step, and the height of the step is to increase the etching range of the silicon wafer. And the height of the silicon wafer.

As the glassy carbon ring, the glassy carbon forming the base is also referred to as non-graphitizable carbon or hard carbon. Raw materials and manufacturing methods may be used, and there is no particular limitation, but there is no risk of impurity contamination during silicon wafer etching. Examples of raw materials include thermosetting resins such as cellulose, furan resin, and phenol resin, and thermoplastic resins. Various production methods based on these raw materials have been proposed. In the present invention, those made of a thermosetting resin having good thermal properties such as thermal conductivity and coefficient of thermal expansion, chemical resistance to etching gas and the like, and corrosion resistance are preferable.

2. Second Cylindrical Ring The composite ring used for the silicon wafer mounting member of the present invention includes a first cylindrical ring (that is, a glassy carbon ring) on which the above silicon wafer is directly mounted.
A ring formed from graphite as a second cylindrical ring bonded to the back surface of the substrate, that is, a ring for cooling or a ring for holding (sometimes called a graphite ring)
Is used. In particular, the graphite ring has no risk of impurity contamination of the silicon wafer during the etching process,
It is used to maintain good positional stability of the silicon wafer.

Since the graphite ring is also used as a cooling ring, it must have good thermal conductivity (that is, high thermal conductivity) and a small difference in thermal expansion coefficient from the glassy carbon ring of the clamp ring. There is. If the thermal conductivity is poor and the difference in the coefficient of thermal expansion is large, the silicon wafer cannot be dealt with, such as large diameter silicon wafers, high processing temperature, rapid heating / quenching, etc. There is a possibility that cracks may occur due to thermal strain or thermal stress. Also, conventionally used aluminum oxides such as alumina and anodized aluminum have a large difference in thermal expansion coefficient from silicon or glassy carbon, and may cause thermal distortion. The effect of using a graphite ring is great.

As the graphite ring, the graphite forming the base is not particularly limited, but it is a material which has no risk of impurity contamination at the time of etching a silicon wafer, has a high thermal conductivity, and has a small difference in thermal expansion coefficient from a glassy carbon ring. For this reason, it is desirable to use high-purity ones. Such graphites include those of semiconductor grade, for example, those that are commercially available,
CX-2123, CX-2114, C
X-2206, Nippon Carbon EGF-262,
EGF-264 and the like. The graphite ring may be a composite of graphite and glassy carbon.

Furthermore, it is desirable that the surface of the graphite ring is coated with glassy carbon. The portion to be coated is at least a surface opposite to the first cylindrical ring, and is exposed to an etching gas during dry etching.

The glassy carbon to be coated is
The thickness is usually 2-3 μm, the coating method,
There is no particular limitation, and any method can be appropriately selected from conventionally used methods. For example, gloss processing or impregnation processing may be used. In particular, graphite has certain resins,
For example, a method in which a glassy carbon coating is formed by coating a polycarbodiimide, a phenol resin, or the like and baking the same is preferable.

The glassy carbon functions as a protective layer for the graphite ring, suppresses dust generation of the graphite ring, and contributes to corrosion resistance and the like. In particular, during dry etching, it suppresses the generation of gas from the graphite ring in a plasma atmosphere, and also prevents the substance forming an oxide layer on the surface of the graphite ring from peeling off and preventing the particles from adhering to the wafer. is there.

3. Glassy Carbon-Graphite Composite Ring The glassy carbon-graphite composite ring of the present invention comprises a glassy carbon ring which is the above-mentioned first cylindrical ring, and a graphite ring which is a second cylindrical ring on its back surface. Are used together. A conductive adhesive for a carbon material is used for joining the glassy carbon ring and the graphite ring, and among them, bonding with a carbon-based adhesive is preferable from the viewpoint of bonding strength.

The carbon-based adhesive is, for example, a mixture of a polycarbodiimide resin and a conductive powder filler. Examples of the powder filler include graphite powder, carbon powder such as carbon black, and coke such as petroleum coke. And the like. The mixing ratio of the powder filler is 100 to 5 parts by weight, preferably 90 to 10 parts by weight, based on 100 parts by weight of the polycarbodiimide resin. In addition, a curing agent for an epoxy resin or a polycarbodiimide resin may be appropriately added to the polycarbodiimide resin in order to increase the adhesive strength.

The use and bonding method of the carbon-based adhesive are as follows.
Usually, a carbon-based adhesive is sandwiched between both substrates to be bonded,
The adhesive layer is pressure-bonded by a clamp or the like so that the thickness of the adhesive layer is 50 μm or less.
Dry and cure at 00 ° C. Then, the base material sandwiching the carbon-based adhesive is bonded by firing and carbonizing. The firing carbonization is performed in a vacuum or in an inert gas such as nitrogen gas. The firing temperature is always higher than the use temperature of the adhesive base material, and is usually in the range of 350 to 3500 ° C., preferably about 2,000 ° C. It is about ° C. The amount of the carbon-based adhesive to be inserted (applied amount) is approximately ²⁰ to 30 mg / cm ^2, which is uniformly applied to both surfaces of the base material to be adhered with a suitable tool, for example, a spatula. The surface roughness of the joint is preferably such that the center line average roughness Ra is in the range of 0.1 to 6.3, and the surface of the joint is appropriately processed as necessary.

In this way, the first cylindrical ring formed of glassy carbon and the second cylindrical ring formed of graphite are joined using the carbon-based adhesive. In this state, the adhesive often protrudes from the bonding surface after firing, and as a result, in order to prevent contamination of the silicon wafer with impurities, wiping off the protruding adhesive and further shaping the final product by machining or the like. In addition, when machining is performed, if the graphite ring is coated with glassy carbon, there is a problem that it is necessary to perform a complicated repair work such as recoating.

Therefore, in the present invention, in order to prevent the adhesive from protruding from the bonding surface, the adhesive is bonded onto the bonding surface of at least one of the tubular rings made of graphite while maintaining the bonding strength. It is an essential requirement that the liquid reservoir has a sufficient volume to prevent it from protruding from the surface, for example, a groove, and if there is a groove, the adhesive does not protrude from the joining surface and the two are firmly bonded. be able to.

Furthermore, in order to firmly adhere the joining surfaces, at least one convex engagement portion is provided on one of the joining surfaces of the first tubular ring and the second tubular ring, and the other is joined. By providing the same number of concave engaging portions on the joining surface, that is, by forming the joining surface in an uneven shape, it is desirable that the joining area between the two increases and the two fit together.

In this way, a composite of the first cylindrical ring formed of glassy carbon and the second cylindrical ring formed of graphite bonded to the back surface is formed, and a specific adhesive By having a shape, etc., there is no danger of the adhesive protruding from the bonding surface, and the bonding is made firm. As a result, impurity contamination is prevented, the positional stability of the wafer is maintained well, and the yield of semiconductor devices is improved. Can be done.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments using drawings, but the present invention is not particularly limited to these embodiments.

Embodiment 1 [Outline of Composite Ring Member for Mounting a Wafer] The composite ring member for mounting a silicon wafer of the present invention is a member for mounting a silicon wafer in a dry etching apparatus for a silicon wafer. 3 is shown in FIG. 3, an outline of the composite ring member for mounting a silicon wafer is shown in FIG. 1, and a partial sectional view thereof is shown in FIG.

In FIGS. 1 and 2, the glassy carbon ring 8 has an outer diameter of 320 mm, an inner diameter of 296 mm, a thickness of a convex portion of 4.8 mm, and a step diameter for mounting the silicon wafer 5 of 303 mm. The one having a depth of 1 mm was used. The outer diameter of the graphite ring 9 is 330
mm, an inner diameter of 296 mm, and a thickness of a concave portion of 5 mm were used. The vitreous carbon forming the base as the vitreous carbon ring 8 is based on a polycarbodiimide group. A trade name: AC-140 manufactured by Nisshinbo is used. The graphite ring 9 is used as the graphite forming the base. Was coated with glassy carbon, and an AC coat manufactured by Nisshinbo Co., Ltd. was used. The glassy carbon ring 8 and the graphite ring 9 were formed into a composite ring via the joint 10. The bonding portion 10 is bonded and bonded using a carbon-based adhesive obtained by mixing a conductive graphite powder with a polycarbodiimide resin. As a method of bonding the carbon-based adhesive, first, the surface of both joints is made to have a surface roughness Ra of 1.6.
Then, a carbon-based adhesive is uniformly applied to both joint surfaces with a spatula at a rate of about 30 mg / cm ² , and the grooves on the graphite joint surface are filled with the carbon-based adhesive. Then, the adhesive layer was pressure-bonded with a weight of 8 kg so that the thickness of the adhesive layer became 50 μm or less, dried in a dryer at 120 ° C. for 2 hours, and cured. Thereafter, the composite ring obtained by applying the carbon-based adhesive and curing by press bonding was calcined and carbonized at about 2000 ° C. to bond the composite ring.

As shown in FIG. 2, the joint surface of the graphite has two grooves of 2 mm width and 2 mm depth on the joint surface of graphite, and the joint surface of glassy carbon has a width of 5 m.
m, a convex portion having a height of 1.6 mm, and a concave portion corresponding to the convex portion are formed on the joining surface of the graphite, and both are fitted to each other. In this way, a composite ring was manufactured, and a tensile test was performed to measure the adhesive strength.

[Comparative Example 1] In Comparative Example 1, except that the shape of the joint portion was not special, and was used in a normal plane shape.
In the same manner as in Example 1, a composite ring was prepared and subjected to a tensile test to measure the adhesive strength.

[Embodiment 2] Hereinafter, Embodiment 2 which is another embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a partial sectional view showing another embodiment of the wafer mounting member according to the present invention, similarly to FIG. As shown in FIG. 4, the shape of the bonding surface was 2 m wide on the graphite bonding surface.
2, two grooves having a depth of 2 mm and a depth of 2 mm are provided at a relatively central portion of the bonding surface adjacent to the concave portion. On the joint surface between the convex portion of 0.6 mm and graphite, there is a concave portion corresponding to the convex portion. Except for changing the shape of the joint surface, a composite ring was prepared and subjected to a tensile test to measure the adhesive strength in the same manner as in Example 1.

As a result, in Examples 1 and 2, the adhesive did not protrude from the bonding surface, and the adhesive strength was about 15 kg / cm ² in both Examples 1 and ² . On the other hand, in Comparative Example 1, the adhesive protruded from the joint surface, and the adhesive strength was about 10 kg / cm ² , which was about 67% of Examples 1 and 2.

From these results, it was found that a glassy carbon-graphite composite was used as a silicon wafer mounting member using a glassy carbon ring as a silicon wafer mounting ring and a graphite ring as a cooling ring to be joined to the glassy carbon ring. Into a ring,
By having a specific bonding shape for the joining,
It was found that the adhesive did not protrude from the bonding surface, and the bonding was firm, and as a result, impurity contamination was prevented, cooling efficiency was high, thermal distortion did not occur, and the yield of silicon wafers was improved. .

[0041]

The composite ring member for mounting a silicon wafer according to the present invention can cope with an increase in the diameter of a silicon wafer.
While using an inexpensive material, there is an effect that impurity contamination is prevented, cooling efficiency is high, thermal distortion does not occur, and the positional stability of the silicon wafer is favorably maintained. for that reason,
The yield of semiconductor devices can be improved, which contributes to a reduction in manufacturing costs.

[Brief description of the drawings]

FIG. 1 is a view showing a member for mounting a wafer;
(A) is a plan view thereof, and (b) is a cross-sectional view thereof.

FIG. 2 is a partial cross-sectional view showing one embodiment of a wafer mounting member according to the present invention.

FIG. 3 is a schematic diagram of a dry etching apparatus.

FIG. 4 is a partial sectional view showing another embodiment of the wafer mounting member according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Etching gas introduction pipe 2 Exhaust pipe 3 Upper electrode 4 Lower electrode 5 Silicon wafer 6 Plasma 7 High frequency power supply 8 Glassy carbon ring 9 Graphite ring 10 Joining surface (part) 11 Groove of joining surface 12 Adhesive

Claims (6)

[Claims] 1. A composite ring member for mounting a silicon wafer, comprising: a first cylindrical ring having a receiving portion on a front surface of which a silicon wafer can be mounted, and a second cylindrical ring joined to a back surface thereof. (A) the first cylindrical ring is formed from glassy carbon, while the second cylindrical ring is formed from graphite having the entire surface coated with glassy carbon, and (b) the first cylindrical ring. At least one of the ring-shaped ring and the second cylindrical ring has a liquid pool portion at a joint surface thereof, which has a sufficient volume to prevent the adhesive from protruding from the joint surface while maintaining the adhesive strength. C) A composite ring member for mounting a silicon wafer, wherein the first cylindrical ring and the second cylindrical ring are firmly joined by a carbon-based adhesive. And (d) a first cylindrical ring and a second cylindrical ring.
The cylindrical ring has at least one convex engaging portion on one of the joining surfaces and the same number of concave engaging portions on the other joining surface so that the joining area of the two increases and the two can fit together. The composite ring member for mounting a silicon wafer according to claim 1, wherein the composite ring member is provided. 3. The composite ring member for mounting on a silicon wafer according to claim 1, wherein the carbon-based adhesive is an adhesive obtained by mixing a conductive powder filler with a polycarbodiimide resin. 4. The composite ring member for mounting a silicon wafer according to claim 3, wherein the conductive powder filler is graphite powder. 5. The silicon wafer mounting according to claim 1, wherein in the second cylindrical ring, the thickness of the glassy carbon coat layer is at least 2-3 μm. Composite ring member. 6. A dry etching apparatus to which the composite ring member for mounting a silicon wafer according to claim 1 is mounted.