JP2006027930A - Black-colored quartz glass, its producing method, and member using the quartz glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide highly light-shielding black-colored quartz glass which is substantially free from metal impurities and has mechanical and thermal characteristics equivalent to those of transparent quartz glass, in other words, bending strength, hardness, coefficient of thermal expansion, thermal conductivity and the like, equivalent to those of the transparent quartz glass; and to provide a method for producing the same. <P>SOLUTION: The black-colored quartz glass is silica glass in which crystalline carbon fine particles having an average diameter of 0.05-1 μm are dispersed in an amount of 0.05-2 wt.% and which has a density of 2.15-2.21 g/cm<SP>3</SP>. The black-colored quartz glass has a transmittance in a wavelength region of 200-10,000 nm of ≤1% when its thickness is 1 mm. The black-colored quartz glass is obtained by mixing an amorphous silica powder having an average diameter of 0.1-1 μm and containing hydroxy group in a content of ≥50 ppm and the crystalline carbon fine particles having an average diameter of 0.05-1 μm so that the addition amount of the carbon fine particles to the weight of the silica powder becomes 0.05-2 wt.%, then forming the resulting mixture, and sintering the formed body at 1,100-1,500°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to black quartz glass. The present invention also relates to an optical component such as a spectroscopic cell using the black quartz glass, a light shielding member for a semiconductor manufacturing apparatus, and an infrared heat absorption / storage member.

  Quartz glass is used in the optical field such as a spectroscopic cell by taking advantage of its good light transmittance and low thermal expansion from the ultraviolet region to the infrared region. Conventionally, in this field, black glass in which a small amount of transition metal oxide is added to quartz glass is used as a site that requires local light shielding, and an optical cell is formed by bonding to transparent quartz glass by thermocompression bonding or the like. It is manufactured. However, in recent years, optical cells have been miniaturized / thinned, and conventional black glass has insufficient light shielding properties, and there is a need for black quartz glass that has higher light shielding properties and can be easily bonded to transparent quartz glass. It has been.

  Quartz glass also has features such as high heat resistance and high chemical purity, and is often used in jigs for semiconductor manufacturing. However, in recent years, heating loss due to transparent quartz glass that allows infrared light to pass through has become a problem in the heat treatment step of the semiconductor manufacturing process. In addition, in a heating process using infrared light, a member that shields objects other than the object to be heated from infrared irradiation is also required. For this reason, the development of black quartz glass that effectively shields infrared rays, has excellent heat insulation properties, withstands thermal shock during rapid heating and cooling, and does not contain metal impurities that cause process contamination is required. Yes.

  Conventionally, the following are known as black glass mainly composed of silica.

  For example, Patent Document 1 proposes black quartz glass in which a metal element compound is added to quartz glass. However, this type of black glass may not have sufficient light-shielding properties, and the metal component contained may cause process contamination, which makes it difficult to apply to the semiconductor manufacturing field.

  Patent Document 2 proposes a black quartz glass having a low relative density produced by reacting a mixture of quartz glass powder and a carbon-forming precursor with ammonia and then foaming the mixture. However, such a porous glass has insufficient airtightness and mechanical strength for the intended use of the present invention.

  Further, Patent Document 3 proposes a black quartz glass in which an organic binder that can be a carbon source is added to silica powder, decomposed by heat treatment to generate carbon, and then carbon is solid-dissolved in the glass network by firing. Yes. However, it is known that such an oxycarbide glass in which carbon is solid-dissolved has mechanical and thermal properties different from those of ordinary quartz glass, such as an increase in hardness and high-temperature viscosity. In addition, the coefficient of thermal expansion is considered to change, and it is difficult to use it by joining or fitting with ordinary transparent quartz glass.

  Further, Patent Document 4 proposes a colored glass sintered body in which colored particles of 0.1% to 30% are dispersed in a volume ratio in glass. However, the subject of the invention is in the glass matrix. This is to shield the leaked light by the embedded colored particles, and the applicability to the structural member as aimed by the present invention is not clear.

Japanese Patent No. 3156733 (Claims) Patent No. 2743982 (Claims) JP 2000-281430 A (Claims) JP 2003-146676 A (Claims)

  The problem to be solved by the present invention is that it contains substantially no metal impurities and has the same mechanical and thermal properties as transparent quartz glass, in other words, the same bending strength, hardness, thermal expansion coefficient, thermal conductivity. And the like, and a method for producing the same.

  Another object is to provide black quartz glass products such as optical parts such as spectroscopic cells manufactured using the black quartz glass, light-shielding members for semiconductor manufacturing apparatuses, and infrared heat absorption / heat storage members.

  As a result of intensive studies to solve the above problems, the present inventors have found that black quartz glass having target physical properties can be obtained in a system in which crystalline carbon fine particles are dispersed in quartz glass. The present invention has been completed.

The black quartz glass of the present invention contains 0.05 to 2% by weight of crystalline carbon based on the weight of silica, and as its form, crystalline carbon fine particles having an average particle diameter of 0.05 to 1 μm are silica. It has a uniformly dispersed structure without being dissolved in the matrix. The glass has a density of 2.15 to 2.21 g / cm ³ and a high bending strength of 70 MPa or more, and a thermal expansion coefficient of 3 × 10 ^{−7 to} 9 × 10 ^{−7, which} is equivalent to that of transparent quartz glass. It is characterized by K- ¹ .

  Next, the manufacturing method of the black quartz glass of this invention is demonstrated.

  The method for producing black quartz glass according to the present invention is characterized in that a mixed powder of amorphous silica and crystalline carbon is molded and sintered densely without reacting or dissolving the silica and carbon. In general, silica and carbon are known to easily undergo decomposition reactions that generate gases such as CO and SiO at high temperatures. However, in the present invention, this decomposition can be achieved by appropriately selecting silica and carbon powder used as raw materials. It was possible to obtain a dense sintered body by suppressing the reaction.

  As the crystalline carbon fine particles used in the black quartz glass of the present invention, it is desirable to use a carbon raw material in which at least the particle surface layer is crystallized in order to suppress reaction with silica during firing. The amount of carbon added is preferably 0.05 to 2% by weight, more preferably 0.1 to 1% by weight, based on the weight of silica. If it is less than 0.05% by weight, sufficient light-shielding properties cannot be obtained, and if it exceeds 2% by weight, sintering is hindered, resulting in a decrease in mechanical strength, generation of particles, and an increase in the coefficient of thermal expansion. Produce. The average particle size of the carbon fine particles is preferably from 0.05 to 1 μm, more preferably from 0.1 to 1 μm, in order to obtain a homogeneous and dense sintered structure and to obtain higher light shielding performance with the same addition amount. 07-0.5 μm. When carbon powder having an average particle size of less than 0.05 μm is used, a reaction with silica at the time of sintering occurs and it becomes difficult to obtain a dense sintered body, and when it exceeds 1 μm, carbon necessary for obtaining sufficient light shielding properties is obtained. The amount added increases and the mechanical properties of the sintered body are reduced.

  As the amorphous silica raw material used for the black quartz glass of the present invention, it is preferable to use a fine powder having a high hydroxyl group content. When the amount of hydroxyl groups in the silica powder is large, there is an effect of lowering the firing temperature, and the reaction between carbon and silica is suppressed and a dense sintered body is easily obtained. As a hydroxyl content, 50 ppm or more is a standard. The average particle size of the amorphous silica powder is preferably 0.1 to 1 μm, more preferably 0.2 to 0.6 μm. If it is less than 0.1 μm, the powder becomes bulky and difficult to form, and if it exceeds 1 μm, the temperature required for sintering rises, and it becomes difficult to densify without reacting silica and carbon. Such silica powder is, for example, synthetic quartz glass obtained by high-temperature hydrolysis of silicon tetrachloride, hydrous fused silica glass obtained by melting silica in an oxyhydrogen flame, or hydrolyzed silicon alkoxide. Synthetic silica powder obtained by post-firing can be obtained by pulverizing to a desired particle size. Alternatively, it is also possible to use spherical silica powder containing a large amount of hydroxyl groups, which is produced by supplying a powder of silica, amorphous silica, metallic silicon or the like having a predetermined particle diameter into a flame such as an oxyhydrogen burner. There is no restriction | limiting in particular regarding the purity of a silica powder, According to a use, it can select suitably.

  The mixing of the amorphous silica powder and the crystalline carbon fine particles is not limited as long as the carbon particles can be uniformly dispersed without agglomeration, and it is common for stirring mixers, ball mills, rocking mixers, V-type mixers, Such a mixing apparatus may be used to mix in a dry powder state or a slurry state. Next, the mixed powder thus obtained is formed into a desired shape. As a forming method, any one of a die press forming, a cold isostatic pressing method, a cast forming method and the like which are usually used for forming ceramics can be used.

  The compact is fired in an oxygen-free state such as in a vacuum or in an inert gas in order to prevent oxidation of carbon particles and crystallization of silica particles. It is preferable that it is 1100-1500 degreeC as sintering temperature, More preferably, it is 1200-1400 degreeC. If the temperature is less than 1100 ° C., the sintering of the silica powder does not proceed sufficiently. If the temperature exceeds 1500 ° C., the reaction between the silica powder and the carbon fine particles becomes a significantly low-density sintered body. In addition, using a pressure sintering method such as a hot pressing method or a hot isostatic pressing is also effective for obtaining a high-density sintered body. In this case, a sintering temperature of 1100 to 1500 ° C. should be selected. Is preferred.

  The black quartz glass thus obtained has a high shielding ability against light in the entire wavelength range from ultraviolet to infrared, and is useful in the entire optical field. In addition to having extremely high light shielding performance, the coefficient of thermal expansion is almost the same as that of transparent quartz glass and can be joined to transparent quartz glass, so that an optical analysis cell made of quartz glass can be produced. Is preferred.

  The black quartz glass obtained by the present invention does not contain metal impurities and has sufficient mechanical strength and thermal shock resistance equivalent to transparent quartz glass. In addition, the black glass also has a high infrared absorptance and a high emissivity of 0.85 or higher. From such characteristics, it is suitable for a member of a heat treatment apparatus used for semiconductor manufacturing. For example, in a wafer heat treatment apparatus, the heat radiation radiated to the outside of the furnace is efficiently shielded by configuring the portion other than the surface through which infrared rays for heating are transmitted with the black quartz glass of the present invention, thereby improving the energy efficiency and the furnace. The internal temperature distribution can be made uniform. In addition, in a heat treatment device that rapidly heats the wafer using an infrared lamp, it efficiently absorbs infrared rays instead of Si wafers with low absorption efficiency of infrared light, and radiates far infrared rays or heats the Si wafer by heat conduction. It can be used as a sample stage or an on-surface heating element that efficiently raises the temperature.

  Moreover, the black quartz glass obtained by the present invention is colored with carbon that does not cause metal contamination, and is easily recognized by the naked eye or an optical sensor. It is useful for identifying and positioning a quartz glass member used in a semiconductor manufacturing process, and can correspond to an automatic conveyance system.

  As described above, according to the present invention, it is possible to provide a highly light-shielding black quartz glass substantially free of metal impurities and having the same mechanical and thermal characteristics as transparent quartz glass and a method for producing the same. it can.

  Further, it is possible to provide black quartz glass products such as optical parts such as a spectral cell produced using the black quartz glass, a light shielding member for a semiconductor manufacturing apparatus, and an infrared heat absorption / heat storage member.

  In order to describe the present invention in more detail, the following examples are given, but the present invention is not limited thereto.

  Samples shown in Table 1 were produced according to the following procedure unless otherwise specified. Silica powder obtained by melting quartz powder in an oxyhydrogen flame and having a hydroxyl group content of 170 to 200 ppm pulverized to an average particle size of 0.3 μm, and graphite powder having a predetermined particle size Were mixed with a ball mill without using a solvent. The obtained mixed powder was molded by die press molding and fired in a vacuum atmosphere.

  The sample characteristics in Table 1 were measured as follows. The density of the sintered body was measured by the Archimedes method. The transmittance was measured by processing the sample to a thickness of 1 mm, measuring the transmittance in the thickness direction using a spectrophotometer, and recorded the highest value in the wavelength range of 200 to 10,000 nm. The bending strength was measured by a four-point bending method based on JIS R1601 after processing a sample to 4 mm × 3 mm × 40 mm. The thermal expansion coefficient was measured in a vacuum with a laser thermal dilatometer. The emissivity was measured with an infrared radiometer at 210 ° C. after processing the sample into 50 mm × 50 mm × 2 mm.

NO. In 2 to 5, 8, 9, 12, 15, 16, 19, and 20, the density is 2.15 to 2.21 g / cm ³ , and the transmittance in the wavelength region of 200 to 10000 nm is 1% at a thickness of 1 mm. Black having a high bending strength of 70 MPa or more, a thermal expansion coefficient of 3 × 10 ^{−7 to} 9 × 10 ⁻⁷ K ⁻¹ equivalent to that of transparent quartz glass, and an emissivity of 0.85 or more. Quartz glass was obtained.

  NO. In No. 1, the amount of carbon added was small, and sufficient light shielding properties could not be obtained. NO. In No. 6, the amount of carbon added was large, sintering was hindered, and a dense sintered body could not be obtained.

  NO. In No. 7, the average particle size of carbon was small, reaction with silica occurred, and a dense sintered body could not be obtained. NO. In No. 10, the average particle size of carbon was large, and sufficient light shielding properties could not be obtained.

  NO. In No. 11, powder having an average particle size of 0.03 μm prepared by a vapor phase method was used as a silica raw material. Since the average particle diameter of silica was small, a molded body having a high density could not be produced, and many bubbles remained in the sintered body. NO. In No. 13, the average particle diameter of silica was large, and a dense sintered body was not obtained.

  NO. In No. 14, the sintering temperature was low, and a dense sintered body could not be obtained. NO. In No. 17, the sintering temperature was high, a reaction between silica and carbon occurred, and a dense sintered body could not be obtained.

  NO. 18 used amorphous carbon as a carbon raw material. A reaction between silica and carbon occurred, and a dense sintered body could not be obtained.

  NO. In No. 19, synthetic silica glass having a hydroxyl group content of 972 ppm produced by hydrolyzing silicon tetrachloride in an oxyhydrogen flame was used as a silica raw material, and the powder was pulverized to an average particle size of 0.3 μm. .

  NO. In No. 20, spherical silica powder having an average particle size of 0.3 μm prepared by supplying finely ground silica into a flame of an oxyhydrogen burner was used as a silica raw material.

  NO. In No. 21, a fused silica glass having a hydroxyl group content of 11 ppm prepared by melting quartz powder using an electric furnace as a silica raw material was pulverized so as to have an average particle size of 0.3 μm. NO. Under the same firing conditions as in No. 19, sintering did not proceed sufficiently, and a dense sintered body could not be obtained. Further, when the firing temperature was raised, a reaction between silica and carbon occurred, and a dense sintered body could not be obtained.

NO. Using the sample prepared in 3 and a commercially available transparent synthetic quartz glass, an optical analysis cell was prepared by the following procedure. Black quartz glass and transparent quartz glass were cut into a predetermined shape, polished, and heated to 1100 ° C. while applying a pressure of 5 kg / cm ² to perform bonding. At the time of joining, deformation, cracking, and joining unevenness did not occur, and it was possible to produce an optical analysis cell. In addition, NO. The thermal expansion coefficients of 3 and transparent quartz glass were 5.8 × 10 ⁻⁷ K ⁻¹ and 5.6 × 10 ⁻⁷ K ⁻¹ , respectively, which are very close numerical values.

Claims (7)

A silica glass having a density of 2.15 to 2.21 g / cm ³ in which 0.05 to 2% by weight of crystalline carbon fine particles having an average particle diameter of 0.05 to 1 μm are dispersed, and having a thickness of 200 mm at a thickness of 1 mm. Black quartz glass having a transmittance of 1% or less in a wavelength range of 10000 nm. The bending strength is 70 MPa or more, and the thermal expansion coefficient at room temperature to 1000 ° C is 3 × 10 ^{−7 to} 9 × 10 ⁻⁷ K ⁻¹ and an emissivity of 0.85 or more. Black quartz glass. Amorphous silica powder having an average particle diameter of 0.1 to 1 μm and containing hydroxyl groups of 50 ppm or more and crystalline carbon fine particles having an average particle diameter of 0.05 to 1 μm are added with respect to the silica powder weight. The black quartz glass according to claim 1 or 2, wherein the mixture is formed and mixed so as to be 0.05 to 2% by weight, and then sintered in a range of 1100 ° C to 1500 ° C. Method. An optical cell for analysis using the black quartz glass according to claim 1. The light-shielding member for semiconductor manufacturing apparatuses using the black quartz glass of Claim 1 or Claim 2. An infrared shielding member for a semiconductor manufacturing apparatus using the black quartz glass according to claim 1. An infrared radiation member for a semiconductor manufacturing apparatus using the black quartz glass according to claim 1.