JP2008179858A - Jig superior in durability for semiconductor-manufacturing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jig for use in a semiconductor-manufacturing apparatus, which has superior corrosion resistance against a corrosive cleaning liquid such as a fluoric acid solution and a nitric acid solution, and a corrosive gas such as a halogen-based gas and a chlorine-based gas, does not produce particles and is superior in durability. <P>SOLUTION: The jig for the semiconductor-manufacturing apparatus has a quartz glass substrate of which the surface is worked into arbitrary surface roughness and surface properties, and then is further covered with a diamond-like carbon film (DLC) that is a hard film. The jig for the semiconductor-manufacturing apparatus has a DLC film of 0.5 μm or thicker, has a durability of 0.005 μm/hr or less against hydrofluoric acid, has a thermal oxidation rate of 0.1 μm/hr or less at 600°C, has an adhesive strength of 95/100 pieces or more, and has such a surface roughness as to follow the surface roughness of the quartz glass substrate. Then, the jig has high corrosion resistance against a halide gas and/or the plasma, inhibits the production of the particles, and shows the superior durability. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a jig for semiconductor manufacturing equipment, and more specifically, quartz having high corrosion resistance against liquids such as hydrofluoric acid and nitric acid having a large corrosive action, and halogen-based and chlorine-based gases, generating less particles and having excellent durability. The present invention relates to a glass CVD jig and an etcher jig.

  In the semiconductor manufacturing field, it is indispensable to use liquids such as hydrofluoric acid and nitric acid that are highly corrosive in the cleaning process, and gases such as halogens and chlorines. Also, many manufacturing apparatuses using plasma are used, and a metal film is formed on a semiconductor element by sputtering a metal material with plasma, or conversely, the surface of the semiconductor element is sputter-etched to form a pattern. Various plasmas are used in various ways. In particular, with the recent miniaturization of semiconductor integrated circuits, the dry etching process using plasma is becoming more important. In these production processes, a halide gas such as a fluorine-based gas or a chlorine-based gas is indispensable.

This halide gas and its plasma are used in various processes such as etching gas in dry etching process and cleaning gas in thermal CVD process because of its high reactivity, and the type of halide gas used is also fluorine-based. F ₂ , HF, CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , CHF ₃ , SF ₆ , NF ₃ which are gases, Cl ₂ , HCl, BCl ₃ , CCl ₄ which are chlorinated gases The types such as Br ₂ and HBr which are bromine-based gases are extremely abundant. In recent years, C ₅ F ₈ , C ₄ F _{6 and the} like having low global warming potential have been proposed.

In addition, in these semiconductor manufacturing devices and liquid crystal manufacturing devices using plasma, quartz glass members that have excellent high-frequency transparency, which is important when plasma is generated, and can manufacture high-purity, complex-shaped members at a relatively low cost. Is frequently used. The reason why the quartz glass member is relatively inexpensive is that the high-purity quartz powder, which is the raw material for quartz glass, is inexpensive, and it is easy to machine and can be welded with an oxyhydrogen flame. There are some points.

Although quartz glass has many excellent properties as described above, etching proceeds from the quartz glass surface at the portion in contact with the halide gas and its plasma, so the quartz glass member is gradually etched and thinned with its use. Phenomenon occurred. This thinning phenomenon of the quartz glass not only shortens the life of the quartz glass member but can also cause abnormal discharge, and thus has been a problem to be solved.
As described above, in such dry etching and wet etching using a liquid such as corrosive hydrofluoric acid or nitric acid, various jigs used are also etched at the same time, and fine powder is generated therefrom, which is a particle. As a result, there is a problem of contaminating the semiconductor element.

In order to solve this problem, Patent Document 1 (Japanese Patent Application Laid-Open No. 5-217946) discloses that a sintered body of alumina, which is a material whose etching rate by plasma is smaller than that of quartz glass, is used for a portion in contact with plasma. Attempts to reduce this thinning phenomenon are known. However, these materials have difficulty in producing high-purity raw material powders, and also have problems such as having grain boundaries, causing dropout of particles during thinning and reducing the yield of semiconductors and liquid crystals. Moreover, there existed a fault that workability was bad compared with quartz glass, and the cost as a member became expensive.
In addition, by adding corrosion-resistant elements to quartz glass, it tries to suppress the thinning phenomenon due to etching while maintaining the excellent characteristics of quartz glass such as high purity, low cost, good workability, and low dust generation. An attempt is being made. This is to provide a quartz glass having a low etching rate by adding an element having a remarkably high sublimation temperature or boiling point of the halide to the quartz glass as compared with the halide of Si which is a constituent element of the quartz glass. Is an attempt.

For example, in Patent Document 2 (Japanese Patent Laid-Open No. 2002-137927), a metal having a boiling point of fluoride higher than the boiling point of fluoride of Si is contained, and the content of bubbles and foreign matters is projected per 100 cm ^3. Quartz glass having an area of less than 100 mm ² has been proposed.
However, the addition of the above-mentioned corrosion-resistant elements to quartz glass not only has the desirable effect of reducing the etching rate and improving the durability, but also destroys the structure of the quartz glass and conversely reduces the durability. It became clear that an undesired effect was also given at the same time.
This is presumably because the introduction of the second component element cuts the SiO ₂ network constituting the quartz glass and introduces non-bridging oxygen having a weak binding force.
Such undesired effects are particularly noticeable, for example, in etching conditions in which high energy ion incidence is relatively high, and the addition of elements increases the etching rate rather than pure quartz glass. There was a serious problem that durability would deteriorate.

Patent Document 3 (Japanese Patent Laid-Open No. 2002-220257) includes 0.1% of a group 3B metal element and a metal element selected from the group consisting of Zr, Y, lanthanoid and actinoid. Quartz glass containing ˜20 wt% has been proposed. However, when the amount of the metal element added to the quartz glass increases, the glass state (amorphous structure) is maintained, but cracks, bubbles, white turbidity, etc. are likely to occur, making it difficult to produce a practical glass. There was a problem.
JP-A-5-217946 JP 2002-137927 A JP 2002-220257 A

  The present invention provides a quartz glass jig for semiconductor manufacturing equipment, such as a CVD jig and an etcher jig, without losing the high purity and good workability and low dust generation characteristics of quartz glass. Is a jig for semiconductor manufacturing equipment that has no internal bubbles or cracks, has excellent wet etching resistance using liquids such as corrosive hydrofluoric acid and nitric acid, and has improved corrosion resistance to halide gas and / or plasma thereof. It is intended to provide.

  As a result of intensive studies to solve such problems, the inventor of the present invention uses a quartz glass substrate processed so that the surface of the substrate has an arbitrary surface property as a jig for a semiconductor manufacturing apparatus. The material surface is coated with a DLC (diamond-like carbon) film, which is a hard film, so that it has excellent etching resistance to hydrofluoric acid, nitric acid, etc., and for CVD using halide gas and / or plasma thereof Providing high-durability semiconductor manufacturing equipment jigs that can be used as jigs and jigs for etchers with high purity without losing the good workability and low dust generation properties of quartz glass. I found out that I can do it.

  Further, the thickness of the DLC film is 0.5 μm or more, the hydrofluoric acid durability of the DLC film is 0.005 μm / hr or less, and the thermal oxidation rate of the DLC film at 600 ° C. is 0.1 μm / hr or less. The surface of the jig for semiconductor manufacturing equipment is directly applied as the surface roughness of the DLC film following the surface roughness of the quartz glass substrate. It is possible to provide a jig for a semiconductor manufacturing apparatus that has high corrosion resistance to halide gas and / or plasma, suppresses particle dust generation, and has excellent durability. The headline and the present invention have been completed.

Diamond-like carbon (DLC) is an amorphous carbon material with characteristics similar to diamond. The DLC film has a high Vickers hardness of 1000 or more, which is similar to diamond, and has a very smooth surface. The friction coefficient is as small as about 0.13.
A major feature of DLC films is that they have microscopic surface smoothness when compared with other hard films, but the surface properties of the substrate are maintained as they are when the film thickness is less than 2 μm. If the quartz glass surface covered with the DLC film is made to have a surface roughness Ra of 0.5 μm or less, surface properties with higher gloss and higher flatness can be obtained.

The DLC film thickness is preferably 0.5 μm or more in order to take advantage of the characteristics of the DLC film. The range of 0.5-2 μm is desirable. When the thickness of the DLC film is 0.5 μm or less, the characteristics such as acid resistance, plasma resistance, high surface hardness, and the generation of particles and impurities are not sufficiently exhibited, and the thickness exceeding 2 μm is the basis. It is impractical because the surface properties of the material are impaired, peeling easily occurs, and the coating process needs to be repeated many times.
When the surface quality of the quartz glass substrate covered with the DLC film is set to a surface property exceeding 0.5 μm, the surface property of the DLC film becomes rough by roughening the surface of the quartz glass substrate. It is effective in improving the adhesion between the material and the film. However, when the surface is roughened, the surface of the base material may be damaged, the coated surface may become inhomogeneous, the strength may be reduced, and the surface smoothness may be impaired.
As a method for roughening the surface of the quartz glass substrate, a physical treatment method such as grinding or sandblasting or a chemical treatment method using a treatment liquid such as hydrofluoric acid can be employed. For example, the surface of the base material is masked with an organic resin film that has been subjected to sandblasting or patterning, etched with a chemical solution to provide a valley-like recess, and a DLC film is formed thereon by plasma CVD. .

However, in the sandblasting method, cracks are likely to occur in the silica glass substrate, and contaminants are taken into the silica glass substrate, which may be released during semiconductor product processing and contaminate the semiconductor element. On the other hand, it is preferable to use a surface treatment solution such as hydrofluoric acid because the chemical treatment method does not include substances that contaminate semiconductor elements such as metal elements and alkali elements. However, since the surface of the substrate is roughened by dissolving it with a chemical solution, roughening is not sufficient or it is difficult to obtain a uniform uneven surface.

Therefore, as a method for roughening the surface of the quartz glass substrate, it is preferable to form a rough surface by thermal spraying. That is, plasma spraying is performed on the surface of the substrate to provide island-like protrusions, and a DLC film is coated thereon by plasma CVD.
Also, to process the quartz glass substrate surface to a predetermined surface roughness, lapping or polishing with normal abrasive grains may be used, but lapping to roughen the surface is similar to sandblasting. Since the sharp projections are formed on the surface, there is a risk of damaging the surface of the workpiece, which may cause scratches, but it is not preferable, but a DLC film is formed on the quartz glass substrate surface. This can alleviate the occurrence.
Thus, by utilizing the property that the surface property of the quartz glass substrate is a mirror surface or a rough surface, or the surface property of the DLC film follows the surface property of the substrate, each of the jigs for the semiconductor manufacturing apparatus is used. By processing the surface roughness of the quartz glass serving as the base material to an arbitrary surface roughness and surface properties depending on the application, a jig for a semiconductor manufacturing apparatus having an arbitrary surface property can be produced.

Next, the DLC film is coated on the quartz glass substrate processed to have an arbitrary surface property as described above. The coating does not need to cover the entire surface of the quartz glass substrate, but it is necessary to cover at least a portion exposed to a corrosive liquid or gas.
Since the DLC film is uniformly formed along the surface shape of the quartz glass, the quartz glass surface may have a slight undulation, but it is corrected to a smooth surface as the surface property indicated by the surface roughness. It is desirable to keep it. The method for forming the DLC film on the quartz glass surface is preferably a CVD method or a sputtering method.

In the CVD method, a gas is used as a film forming material. In the plasma CVD method, plasma is used to decompose the source gas. A hydrocarbon gas such as methane gas is used as the source gas. Before film formation, the vacuum container is evacuated to 10 ⁻⁶ Torr, and the processing substrate is cleaned with hydrogen plasma. Thereafter, methane gas, which is a film forming gas, is introduced, decomposed by plasma, and a DLC film is formed on the substrate.
In the sputtering method, a thin film material is formed by evaporating a solid film material in a vacuum or in a gas. In this sputtering method, ions are made to collide with a target, and the repelled target atoms are made to collide with an object to form a film. The surface roughness of quartz glass which is the base material of a jig for semiconductor manufacturing equipment is almost reduced. The film can be formed as it is without being changed. For this reason, a very smooth surface having a surface roughness Ra of 0.01 μm or less can be obtained uniformly in a form corresponding to the surface state of quartz glass.

Usually, when coating on quartz glass, if the quartz glass surface is a mirror surface, the adhesion tends to be weakened. For this reason, it was necessary to make the surface state a rough surface and to increase the adhesion area of the surface by forming the rough surface of the rough surface to make it difficult to peel off. However, in the case of a DLC film, a strong adhesive force is maintained even if the quartz glass substrate is a mirror surface. This is considered to be due to the good compatibility between the thermal expansion coefficients of quartz glass and the DLC film. Quartz glass is known to have a very low thermal expansion coefficient of 5 × 10 ⁻⁷ , but the DLC film is also as low as 2 × 10 ⁻⁶ , showing an expansion coefficient almost equal to that of quartz glass. Therefore, it is presumed that even with such surface roughness, the quartz glass and the DLC film are not peeled off due to the compatibility of the thermal expansion coefficients, and strong adhesion is maintained. Even in the present invention, it has been confirmed from the verification results by Japanese Industrial Standards that even if the surface of the quartz glass substrate is a mirror surface, the adhesive strength of the DLC film is 95/100 or more.
Further, in terms of high temperature durability, the knowledge that the thermal oxidation rate of the DLC film at 600 ° C. was 0.1 μm / h or less was obtained, which can be presumed to be due to the compatibility of the thermal expansion coefficients.

The DLC film thickness is preferably 0.5 μm or more in order to take advantage of the characteristics of the DLC film, and more preferably in the range of 0.5 to 2 μm. However, the film thickness can be adjusted by sputtering processing conditions.
A DLC film may be provided directly on a mirror-polished surface of a quartz glass substrate or on an unpolished rough surface. However, an Si compound film is provided as an intermediate layer, and a DLC film is formed thereon. Alternatively, the intermediate layer may be a multi-layered film.

In the jig for semiconductor manufacturing apparatus of the present invention, the quartz glass substrate is coated with the DLC film, and the DLC film has substantially the same thermal expansion coefficient as that of quartz glass. It is the best to do.
Further, the DLC film is firmly adhered, does not generate film stress, has excellent high temperature durability, and becomes a uniform and strong film. Furthermore, coating with a DLC film improves the corrosion resistance against corrosive cleaning liquids such as hydrofluoric acid and corrosive gases such as fluorine, preventing the penetration of impurities into the jig base material and the reverse diffusion into the furnace atmosphere. In addition, contamination of the semiconductor element can be reduced. Further, since the DLC film has a smooth surface, adhesion of dust is prevented, and since it is hard and wear-resistant, generation of particles due to contact with an object to be processed is prevented. Furthermore, since quartz glass can be processed with high dimensional accuracy, it can be applied to various shapes, and can be applied as various jigs for semiconductor manufacturing apparatuses by taking advantage of quartz glass as a base material.

By coating a quartz glass base material, which is the base material for semiconductor manufacturing equipment jigs, with a hard coating of diamond-like carbon (DLC), the corrosion resistance against corrosive cleaning liquids and corrosive gases is improved. It becomes a jig for a semiconductor manufacturing apparatus that is excellent in plasma resistance and high temperature durability, has high film retention performance, and suppresses generation of particles.

Example Two types of substrates were prepared, one having a surface of Φ125 mm × 0.5 mm quartz glass optically polished as a substrate and the other having lapped with a # 1000 abrasive to a surface roughness Ra of 0.2 μm. A cross-shaped mask having a width of 2 mm was applied to one of the two types.

Next, the quartz glass substrate whose film-coated surface has been sufficiently cleaned is set in a vacuum chamber of a sputtering apparatus, exhausted to a high vacuum of 2 × 10 ⁻³ Pa or less, and then the surface of the quartz glass substrate and the chamber inner surface Preheat chamber for degassing. Next, a negative bias voltage of 400 V is applied to the quartz glass substrate, a hot filament plasma source is operated in an Ar gas atmosphere at a pressure of 1 Pa, and the bombardment that causes the generated Ar ions to collide with the quartz glass substrate. Perform the process. This process etches and cleans the surface of the quartz glass substrate with high energy ions, and raises the temperature of the quartz glass substrate, thereby further strengthening the adhesion of the DLC film formed thereafter. This process is performed for about 20 minutes.

Thereafter, the process of coating the DLC film is started. A solid graphite target is used as the sputtering target. The Ar gas pressure is changed to a sputtering pressure of about 0.5 Pa, and while applying a bias voltage of about 100 V to the quartz glass substrate, an electric power of about 3 kW is supplied to the sputtering source to cause glow discharge. In this way, ions are made to collide with the graphite target, and the quartz glass surface is coated with a DLC film by the carbon atoms repelled. By adjusting the sputtering power and the coating time, when the set film thickness reaches 1000 nm, the power supply to the sputtering source is stopped and the coating is finished.
After cooling the quartz glass substrate on which the DLC film is formed, the quartz glass substrate is taken out from the vacuum chamber, and the state of the film of the two types of quartz glass substrate is subjected to an etching rate evaluation test for hydrofluoric acid solution, surface observation before and after immersion in hydrofluoric acid, high temperature Durability test, surface observation before and after high temperature durability test, adhesion strength evaluation test between quartz glass substrate and film by JIS, and film thickness and film surface roughness evaluation were performed.

フッ酸濃度は１０％及び２０％、浸漬時間は２時間、５時間及び２５時間とした。ＤＬＣ膜の初期膜厚である１０００ｎｍに対する減耗は認められず、いずれもＤＬＣ膜のフッ酸耐久性が０．００５μｍ／ｈｒ以下である。 Table 1 shows the etching rate evaluation test results for the hydrofluoric acid solution.

The hydrofluoric acid concentration was 10% and 20%, and the immersion time was 2, 5, and 25 hours. No depletion with respect to 1000 nm, which is the initial film thickness of the DLC film, was observed, and the hydrofluoric acid durability of the DLC film was 0.005 μm / hr or less.

試験サンプルは電気炉内に設置した石英ガラス管の中に入れ、窒素ガスを流しながら２００℃、４００℃、６００℃に各々加熱し、当該温度で各々５時間保持した後、冷却後に膜厚を触針式段差計で測定し、ＤＬＣ膜の酸化による減耗量を評価した。 Although the surface was observed with an optical microscope and an atomic force microscope (AFM), neither DLC film was peeled off nor scratched, and the DLC film was uniformly and firmly formed over the entire surface of the quartz glass.
Table 2 shows the results of the high temperature durability test.

The test sample is put in a quartz glass tube installed in an electric furnace, heated to 200 ° C., 400 ° C., and 600 ° C. while flowing nitrogen gas, held at that temperature for 5 hours, and then cooled to have a film thickness. The amount of wear due to oxidation of the DLC film was evaluated by measuring with a stylus type step gauge.

As shown in Table 2, the thermal oxidation rate of the DLC film at 600 ° C. is 0.1 μm / hr or less, and the usable temperature range of the jig for semiconductor manufacturing apparatus of the present invention is up to 600 ° C. A temperature lower than 400 ° C. at which the disappearance of oxidation of the DLC film is observed is preferable as a practical use temperature in consideration of deterioration of the DLC film characteristics.
Although it was observed with an environmental control electron microscope at a magnification of 10,000, no change was observed in the surface properties.

密着力評価試験は、日本工業規格であるＪＩＳ Ｋ５６００−５−６「付着性：クロスカット法」に準じて試験を行った。試験ピースに粘着テープを貼り付け、その上から１ｃｍ角に１００マスの切り込みを入れ、次いで粘着テープを引き剥がすことで試験ピース上に残った膜の数をカウントして評価した結果、いずれも１００マス中で膜が剥がれたものはなく、ＤＬＣ膜の密着力が９５／１００個以上であることが確認され、これまでの結果と同様に、石英ガラス基材表面を鏡面状に光学研磨したものと表面粗さＲａ０．２μｍに仕上げたものとは同じ結果であり、石英ガラス基材の表面が鏡面であっても強固な密着力があることが確認された。 Table 3 shows the results of the adhesion evaluation test.

The adhesion evaluation test was performed according to JIS K5600-5-6 “Adhesiveness: Cross-cut method” which is a Japanese industrial standard. Adhesive tape was affixed to the test piece, and 100 square notches were cut into a 1 cm square from the top, and then the number of films remaining on the test piece was counted by peeling off the adhesive tape. There was no film peeled off in the mass, and it was confirmed that the adhesion of the DLC film was 95/100 or more, and the surface of the quartz glass substrate was optically polished into a mirror surface like the previous results And the surface finished with a surface roughness Ra of 0.2 μm were the same result, and it was confirmed that even if the surface of the quartz glass substrate was a mirror surface, there was strong adhesion.

膜厚は３次元表面構造解析顕微鏡で計測し、表面粗さは原子間力顕微鏡（ＡＦＭ）で測定した。いずれも非常に良好な平滑面となっていることがわかる。 Table 4 shows the film thickness and film surface roughness evaluation results of the quartz glass substrate surface having a mirror surface.

The film thickness was measured with a three-dimensional surface structure analysis microscope, and the surface roughness was measured with an atomic force microscope (AFM). It can be seen that both have a very good smooth surface.

Claims (7)

A jig for a semiconductor manufacturing apparatus made of quartz glass having a predetermined surface roughness and surface properties, the surface of which is covered with a DLC (diamond-like carbon) film. Jig for semiconductor manufacturing equipment. 2. The jig for a semiconductor manufacturing apparatus according to claim 1, wherein the thickness of the DLC film is 0.5 μm or more and less than 2 μm. 3. The jig for a semiconductor manufacturing apparatus according to claim 1, wherein the DLC film has a hydrofluoric acid durability of 0.005 [mu] m / hr or less. The jig for a semiconductor manufacturing apparatus according to any one of claims 1 to 3, wherein the thermal oxidation rate of the DLC film at 600 ° C is 0.1 µm / hr or less. 5. The jig for a semiconductor manufacturing apparatus according to claim 1, wherein the adhesion force of the DLC film is 95/100 or more. 6. The jig for a semiconductor manufacturing apparatus according to claim 2, wherein the surface roughness of the DLC film is formed as a surface roughness that follows the surface roughness of the quartz glass substrate. 7. The semiconductor manufacturing apparatus jig according to claim 1, wherein the semiconductor manufacturing apparatus jig is a CVD jig or an etcher jig used in plasma etching.