JP4390872B2 - Semiconductor manufacturing apparatus member and method for manufacturing semiconductor manufacturing apparatus member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a member for a semiconductor manufacturing apparatus.And its manufacturing methodIn particular, a semiconductor manufacturing apparatus member having excellent durability and high characteristics using a silicon carbide sintered body having excellent characteristicsAnd its manufacturing methodIt is about.
[0002]
[Prior art]
Semiconductor manufacturing equipment members such as soaking tubes (liner tubes) used to manufacture semiconductors, reaction tubes (process tubes) through which reaction gases flow, jigs (wafer boats) on which semiconductor wafers are placed are dense, heat resistant, Since high characteristics such as rigidity are required, the use of silicon carbide tends to increase. Conventionally, when a member for a semiconductor manufacturing apparatus is produced using silicon carbide, a method in which a binder is added to a raw material powder, and after molding, firing, sintering, and a process of melting and impregnating metal silicon has been widely used. Yes.
[0003]
A conventional member for a semiconductor manufacturing apparatus using silicon carbide has a problem of contaminating a semiconductor wafer to be manufactured because metal impurities inside silicon carbide diffuse and move in the member during high temperature processing. As a method of preventing contamination of the wafer due to the impurities of silicon carbide, a method of producing a member with a high-purity raw material, and forming a high-purity silicon carbide film on the surface of the member by CVD (chemical vapor deposition) treatment Method etc.
Yes.
[0004]
However, even if high-purity silicon carbide with an impure metal content on the order of several ppm or less is used, it is necessary to purify the porous sintered body before impregnation with metal silicon. There was a problem of metal silicon elution in the washing and acid treatment processes. Therefore, in order to further increase the purity and improve the durability, a CVD process is performed to coat the surface of the member with a silicon carbide film. However, this CVD process requires a large amount of equipment and increases the production cost. Further, this CVD film has a problem that the durability of the anti-contamination effect is lacking due to peeling from the base material or pinholes or cracks during repeated rapid heating and rapid cooling cycles.
[0005]
In addition, the base material for performing this CVD process is formed in the shape of a jig in advance by a reaction sintering method by means such as casting, but in recent years the wafer size has increased and the shape of the reaction tube has changed. Along with this, various shapes of the base material are required, and a mold is required for each member, which also increases the manufacturing cost.
[0006]
[Problems to be solved by the invention]
  The present invention has been made in consideration of the above-mentioned problems, and its object is to prevent contamination by metal impurities such as wafers using a high-density and high-purity silicon carbide sintered body. Can be manufactured, has low productivity, has low durability, and has excellent durability and solvent resistance.And its manufacturing methodIs to provide.
[0007]
[Means for Solving the Problems]
  As a result of intensive studies on the development of the sintering method as described above, the present inventors represented carbon on the surface of the silicon carbide powder in advance.It is an organic compound that produces carbon by heating.Producing semiconductors with excellent characteristics by using high-density and high-purity sintered silicon carbide obtained by combining appropriate amounts of non-metallic sintering aids and combining hot pressing under specific conditions It discovered that the member for apparatuses was obtained and completed this invention.
[0008]
  That is, the member for a semiconductor manufacturing apparatus of the present invention comprises a mixture of silicon carbide powder and a nonmetallic sintering aid that is an organic compound that generates carbon by heating.After performing a first temperature rise to be heated to 700 ° C. and held and a second temperature rise to be further heated to 1500 ° C. and held,Temperature 2000-2400 ° C, pressure 300-700kgf / cm²A sintered body obtained by sintering by hot pressing in a non-oxidizing atmosphere and having a density of 2.9 g / cm^ThreeAs described above, a silicon carbide sintered body having a total content of impurity elements of less than 1 ppm is used.
  Moreover, the method for producing a member for a semiconductor manufacturing apparatus according to the present invention comprises a step of preparing a mixture of silicon carbide powder and a nonmetallic sintering aid that is an organic compound that generates carbon by heating, and the mixtureA first temperature raising step of heating and holding up to 700 ° C., a second temperature raising step of heating and holding up to 1500 ° C., and thenTemperature 2000-2400 ° C, pressure 300-700kgf / cm²And hot pressing in a non-oxidizing atmosphere.
[0009]
  The silicon carbide sintered body used here preferably has a specific resistance of 1 Ω · cm or less and a thermal conductivity of 200 W / m · k or more.New.
[0010]
Since the semiconductor manufacturing apparatus member of the present invention uses a high-purity and high-density silicon carbide sintered body, it does not contain metallic silicon, and is strong even by heating exceeding 1500 ° C., which is the melting point of silicon. Is not stable and is stable to acid treatment. Further, since this member can be easily subjected to electric discharge machining, it can also be made as an assembly type, thereby increasing the degree of freedom in designing the semiconductor manufacturing apparatus member, and even when manufacturing a large member, This can be handled by a large-scale sintered body manufacturing apparatus.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in further detail below. First, the silicon carbide sintered body constituting the member for a semiconductor manufacturing apparatus of the present invention will be described.
[0012]
The silicon carbide sintered body used as the base material of the member for a semiconductor manufacturing apparatus of the present invention uses, as a raw material, silicon carbide powder that is α-type, β-type, amorphous, or a mixture thereof. Β-type silicon carbide powder is preferably used. The grade of this β-type silicon carbide powder is not particularly limited, and for example, commercially available β-type silicon carbide powder can be used. The particle size of the silicon carbide powder is preferably small from the viewpoint of densification, and is preferably about 0.01 to 10 μm, and more preferably about 0.05 to 1 μm. If the particle size is less than 0.01 μm, handling in processing steps such as weighing and mixing becomes difficult, and if it exceeds 10 μm, the specific surface area is small, that is, the contact area with the adjacent powder becomes small, and the density increases. Is not preferable because it becomes difficult.
[0013]
As a preferred embodiment of the silicon carbide raw material powder, the particle diameter is 0.05 to 1 μm and the specific surface area is 5 m.²/ G or more, free carbon 1% or less, oxygen content 1% or less is preferably used. Further, the particle size distribution of the silicon carbide powder to be used is not particularly limited, and at the time of producing a silicon carbide sintered body, two or more maximums are obtained from the viewpoint of improving the packing density of the powder and the reactivity of the silicon carbide. Those having a value can also be used.
[0014]
In order to obtain a high-purity silicon carbide sintered body, a high-purity silicon carbide powder may be used as the raw material silicon carbide powder.
[0015]
High purity silicon carbide powder includes, for example, a silicon source containing at least one or more liquid silicon compounds, a carbon source containing at least one or more liquid organic compounds that generate carbon by heating, and a polymerization or crosslinking catalyst. And a baking step of baking a solid material obtained by homogeneous mixing in a non-oxidizing atmosphere.
[0016]
As a silicon compound (hereinafter, appropriately referred to as a silicon source) used for production of high-purity silicon carbide powder, a liquid and a solid can be used in combination, but at least one is selected from a liquid It must be done. As the liquid, a polymer of alkoxysilane (mono-, di-, tri-, tetra-) and tetraalkoxysilane is used. Among the alkoxysilanes, tetraalkoxysilane is preferably used, and specific examples include methoxysilane, ethoxysilane, propoxysilane, butoxysilane, and the like. From the viewpoint of handling, ethoxysilane is preferable. Examples of the tetraalkoxysilane polymer include a low molecular weight polymer (oligomer) having a degree of polymerization of about 2 to 15 and a silicate polymer having a higher degree of polymerization, which are liquid. Examples of solid materials that can be used in combination with these include silicon oxide. In the present invention, silicon oxide includes silica sol (a colloidal ultrafine silica-containing liquid containing OH groups and alkoxyl groups inside), silicon dioxide (silica gel, fine silica, quartz powder) and the like in addition to SiO.
[0017]
Among these silicon sources, from the viewpoint of good homogeneity and handling properties, an oligomer of tetraethoxysilane and a mixture of an oligomer of tetraethoxysilane and fine powder silica are preferable. These silicon sources are high-purity substances, and the initial impurity content is preferably 20 ppm or less, more preferably 5 ppm or less.
[0018]
Moreover, as an organic compound which produces | generates carbon by the heating used for manufacture of a high purity silicon carbide powder, in addition to a liquid thing, a liquid thing and a solid thing can be used together, and a residual carbon ratio is high, In addition, an organic compound that is polymerized or cross-linked by a catalyst or heating, specifically, a monomer or prepolymer of a resin such as phenol resin, furan resin, polyimide, polyurethane, and polyvinyl alcohol is preferable. In addition, cellulose, sucrose, pitch, and tar Etc., and a resol type phenol resin is particularly preferable. In addition, the purity can be appropriately controlled and selected depending on the purpose, but when a high-purity silicon carbide powder is required, it is desirable to use an organic compound that does not contain 5 ppm or more of each metal.
[0019]
The molar ratio of carbon to silicon (hereinafter abbreviated as C / Si ratio) in producing high-purity silicon carbide powder that is a raw material powder used in the present invention is obtained by carbonizing the mixture at 1000 ° C. The resulting carbide intermediate is defined by elemental analysis. Stoichiometrically, when the C / Si ratio is 3.0, the free carbon in the generated silicon carbide should be 0%. However, in practice, the low C / Si ratio is caused by volatilization of the SiO gas generated at the same time. Free carbon is generated in It is important to determine the formulation in advance so that the amount of free carbon in the generated silicon carbide powder does not become an amount that is not suitable for the purpose of manufacturing a sintered body or the like. Usually, in firing at 1600 ° C. or more near 1 atm, free carbon can be suppressed when the C / Si ratio is set to 2.0 to 2.5, and this range can be suitably used. When the C / Si ratio is 2.5 or more, free carbon significantly increases. However, since this free carbon has an effect of suppressing grain growth, it may be appropriately selected according to the purpose of grain formation. However, when the atmosphere is fired at a low pressure or a high pressure, the C / Si ratio for obtaining pure silicon carbide varies, and in this case, it is not necessarily limited to the range of the C / Si ratio.
[0020]
In addition, since the action at the time of sintering free carbon is very weak compared to that due to carbon derived from the nonmetallic sintering aid coated on the surface of the silicon carbide powder used in the present invention, Basically it can be ignored.
[0021]
Further, in the present invention, in order to obtain a solid material in which the silicon source and the organic compound that generates carbon by heating are homogeneously mixed, the mixture of the silicon source and the organic compound is cured to form a solid material as necessary. Done. Examples of the curing method include a method of crosslinking by heating, a method of curing with a curing catalyst, and a method of electron beam or radiation. The curing catalyst can be appropriately selected according to the carbon source, but in the case of phenol resin or furan resin, acids such as toluenesulfonic acid, toluenecarboxylic acid, acetic acid, oxalic acid, hydrochloric acid, sulfuric acid, and amines such as hexamine Etc. are used.
[0022]
This raw material mixed solid is heated and carbonized as necessary. This is done by heating the solid for 30 minutes to 120 minutes at 800 ° C. to 1000 ° C. in a non-oxidizing atmosphere such as nitrogen or argon.
[0023]
Furthermore, silicon carbide is produced by heating this carbide at 1350 ° C. or more and 2000 ° C. or less in a non-oxidizing atmosphere such as argon. The firing temperature and time can be appropriately selected according to the desired properties such as particle size, but firing at 1600 ° C. to 1900 ° C. is desirable for more efficient production.
[0024]
In addition, when a powder with higher purity is required, impurities can be further removed by performing a heat treatment at 2000 to 2100 ° C. for 5 to 20 minutes during the aforementioned baking.
[0025]
From the above, as a method for obtaining a particularly high-purity silicon carbide powder, the raw material powder production method described in JP-A-9-78605 “Production method of single crystal” can be used. The raw material powder manufacturing method described in the method for manufacturing a single crystal, that is, high purity in which carbon is generated by heating using one or more selected from high-purity tetraalkoxysilane and tetraalkoxysilane polymer as a silicon source A silicon carbide production step of obtaining a silicon carbide powder by heating and firing a mixture obtained by uniformly mixing an organic compound as a carbon source in a non-oxidizing atmosphere, and the obtained silicon carbide powder, A post-treatment step of holding at a temperature of 1700 ° C. or higher and lower than 2000 ° C., and performing the heating at a temperature of 2000 ° C. to 2100 ° C. for 5 to 20 minutes at least once during the holding of the temperature. To obtain a silicon carbide powder having a content of each impurity element of 0.5 ppm or less by performing a method of producing high-purity silicon carbide powder, etc. Rukoto can.
[0026]
Further, in the production of a silicon carbide sintered body that can be suitably used for a member for a semiconductor manufacturing apparatus of the present invention, the non-metallic sintering aid used by mixing with the silicon carbide powder is carbon by heating. The so-called carbon source that is generated is used, and includes organic compounds that generate carbon by heating, or silicon carbide powder (particle size: about 0.01 to 1 μm) whose surface is coated with these compounds. From the viewpoint of the above, the former is preferable.
[0027]
Specific examples of organic compounds that generate carbon by heating include coal tar pitch, pitch tar, phenol resin, furan resin, epoxy resin, phenoxy resin, monosaccharides such as glucose, sucrose, and the like with a high residual carbon ratio. Various saccharides, such as saccharides, polysaccharides, such as a cellulose and starch, are mentioned. For the purpose of being homogeneously mixed with silicon carbide powder, those that are liquid at room temperature, those that dissolve in a solvent, those that soften by heating such as thermoplasticity or heat melting, or those that become liquid are suitable. Among them, a phenol resin, particularly a resol type phenol resin, having high strength of the obtained molded body is preferable.
[0028]
When this organic compound is heated, it produces inorganic carbon compounds such as carbon black and graphite in the system, which are considered to act effectively as a sintering aid. Even if carbon black or graphite powder is added as a sintering aid, the effect of the present invention cannot be obtained.
[0029]
In the present invention, when obtaining a mixture of the silicon carbide powder and the nonmetallic sintering aid, it is preferable to mix the nonmetallic sintering aid dissolved or dispersed in a solvent. The solvent is suitable for a compound used as a non-metallic sintering aid, specifically, for a phenol resin that is an organic compound that generates carbon by suitable heating, a lower solvent such as ethyl alcohol. Alcohols, ethyl ether, acetone and the like can be selected. Also, it is preferable to use a non-metallic sintering aid and a solvent having a low impurity content.
[0030]
If the amount of the non-metallic sintering aid mixed with the silicon carbide powder is too small, the density of the sintered body will not increase, and if it is too large, the free carbon contained in the sintered body will increase, which will hinder densification. Depending on the type of non-metallic sintering aid used, the amount of addition may be adjusted to generally 10% by weight or less, preferably 2 to 5% by weight. preferable. This amount can be determined by previously quantifying the amount of silica (silicon oxide) on the surface of the silicon carbide powder using hydrofluoric acid and calculating the amount stoichiometrically sufficient for the reduction.
[0031]
The amount added as carbon here means that the silica quantified by the above method is carbon derived from a non-metallic sintering aid and is reduced by the following chemical reaction formula, This is a value obtained in consideration of the residual carbon ratio after pyrolysis of the sintering aid (ratio of generating carbon in the nonmetallic sintering aid).
[0032]
[Chemical 1]
SiO₂  + 3C → SiC + 2CO
In the silicon carbide sintered body according to the present invention, the total of carbon atoms derived from silicon carbide and nonmetallic sintering aids contained in the silicon carbide sintered body is 30% by weight. It is preferably 40% by weight or less. When the content is 30% by weight or less, the proportion of impurities contained in the sintered body increases, and when it exceeds 40% by weight, the carbon content increases and the density of the resulting sintered body decreases, and the sintered body is sintered. It is not preferable because various properties such as strength and oxidation resistance of the body deteriorate.
[0033]
In producing the silicon carbide sintered body according to the present invention, first, silicon carbide powder and a nonmetallic sintering aid are mixed homogeneously. As described above, phenol which is a nonmetallic sintering aid is used. The resin is dissolved in a solvent such as ethyl alcohol and mixed well with the silicon carbide powder. Mixing can be performed by a known mixing means such as a mixer or a planetary ball mill. The mixing is preferably performed for 10 to 30 hours, particularly 16 to 24 hours. After thorough mixing, the solvent is removed at a temperature compatible with the physical properties of the solvent, such as 50-60 ° C. in the case of ethyl alcohol, and the mixture is evaporated to dryness. To obtain a raw material powder of the mixture. From the viewpoint of high purity, it is necessary to use a synthetic resin that contains as little metal as possible for the material of the ball mill container and the ball. In drying, a granulator such as a spray dryer may be used.
[0034]
The sintering step, which is an essential step in the production method for producing a sintered body suitable for a raw material for a semiconductor manufacturing apparatus according to the present invention, is a powder mixture or a molded body of a powder mixture obtained by a molding step described later. , Temperature 2000-2400 ° C., pressure 300-700 kgf / cm²This is a step of placing in a molding die in a non-oxidizing atmosphere and hot pressing.
[0035]
From the viewpoint of the purity of the obtained sintered body, the molding die used here uses a graphite material for part or all of the mold so that the molded body and the metal part of the mold do not come into direct contact with each other. Alternatively, it is preferable to interpose a Teflon sheet or the like in the mold.
[0036]
In the present invention, the pressure of the hot press is 300 to 700 kgf / cm.²The pressure can be applied under the conditions of 400 kgf / cm.²When the pressure is applied as described above, it is necessary to select a hot-pressed part used here, for example, a die, a punch or the like having good pressure resistance.
[0037]
  Here, the sintering process will be described in detail. Before the hot pressing process for producing a sintered body, heating and heating are performed under the following conditions to sufficiently remove impurities, and non-metallic sintering. After the auxiliary agent is completely carbonized, hot pressing under the above conditions may be performed.is necessary.
[0038]
  That is, the following two-step temperature raising process can be performed.is necessary. First, the inside of the furnace is gently heated from room temperature to 700 ° C. under vacuum. Here, when it is difficult to control the temperature of the high-temperature furnace, the temperature may be continuously increased up to 700 ° C.^-FourTorr, the temperature is gradually raised from room temperature to 200 ° C., and the temperature is maintained for a certain period of time. Thereafter, the temperature is further gradually raised and heated to 700 ° C. Further, it is held for a certain time at a temperature of around 700 ° C. In this first temperature raising step, adsorbed moisture and organic solvent are desorbed, and further, carbonization by thermal decomposition of the nonmetallic sintering aid is performed. A suitable range of the time for maintaining the temperature at around 200 ° C. or around 700 ° C. is selected depending on the size of the sintered body. Whether or not the holding time is sufficient can make it easy to identify the time when the decrease in the degree of vacuum is reduced to some extent. If rapid heating is performed at this stage, impurities are not sufficiently removed and carbonization of the nonmetallic sintering aid is not sufficiently performed, which may cause cracks and voids in the molded body, which is not preferable.
[0039]
As an example, for a sample of about 5-10 g, 10^-FourTorr is gradually raised from room temperature to 200 ° C., held at that temperature for about 30 minutes, and then further gently raised and heated to 700 ° C. The time from room temperature to 700 ° C. Is about 6 to 10 hours, preferably about 8 hours. Furthermore, it is preferable to hold at about 700 ° C. for about 2 to 5 hours.
[0040]
In vacuum, from 700 ° C. to 1500 ° C., the temperature is increased over 6 to 9 hours under the above conditions, and the temperature is maintained at 1500 ° C. for 1 to 5 hours. In this step, it is considered that a reduction reaction of silicon dioxide and silicon oxide is performed. In order to remove oxygen bonded to silicon, it is important to complete the reduction reaction sufficiently. The holding time at a temperature of 1500 ° C. is sufficient until generation of carbon monoxide as a by-product by the reduction reaction is completed. That is, it is necessary to carry out the process until the degree of vacuum decreases and the degree of vacuum is restored to around 1300 ° C., which is the temperature before the start of the reduction reaction. By the reduction reaction in the second temperature raising step, silicon dioxide that adheres to the surface of the silicon carbide powder and inhibits densification and causes large grain growth is removed. Gases containing SiO and CO generated during this reduction reaction are accompanied by impurity elements, but these generated gases are constantly discharged and removed by the vacuum pump to the reaction furnace. It is preferable to sufficiently maintain the temperature.
[0041]
  After these heating steps are completed, high-pressure hot pressing is performed.Yeah.Sintering starts when the temperature rises above 1500 ° C., but at that time, 300 to 700 kgf / cm in order to suppress abnormal grain growth.²Pressurization is started as an indication of the degree. Thereafter, an inert gas is introduced to make the inside of the furnace a non-oxidizing atmosphere. Nitrogen or argon is used as this inert gas, but it is desirable to use argon gas because it is non-reactive even at high temperatures.
[0042]
After making the inside of the furnace a non-oxidizing atmosphere, the temperature is 2000-2400 ° C., the pressure 300-700 kgf / cm.²Heat and pressurize so that The pressure at the time of pressing can be selected according to the particle size of the raw material powder, and those having a small particle size of the raw material powder can obtain a suitable sintered body even when the pressure at the time of pressurization is relatively small. In addition, the temperature rise from 1500 ° C. to the maximum temperature of 2000 to 2400 ° C. is performed over 2 to 4 hours, but the sintering proceeds rapidly at 1850 to 1900 ° C. Further, the sintering is completed at this maximum temperature for 1 to 3 hours.
[0043]
  Here, if the maximum temperature is less than 2000 ° C., the densification is insufficient, and if it exceeds 2400 ° C., the powder or the raw material of the molded body may be sublimated (decomposed). Also, pressurization condition is300kgf / cm²If it is less than 700, the densification is insufficient, and 700 kgf / cm.²Exceeding this may cause damage to a mold such as a graphite mold, which is not preferable from the viewpoint of production efficiency.
[0044]
Also in this sintering step, from the viewpoint of maintaining the purity of the sintered body to be obtained, it is preferable to use a high-purity graphite raw material for the graphite mold and the heat insulating material used in the heating furnace, and the graphite raw material has a high purity. Although what was processed is used, specifically, what is sufficiently baked at a temperature of 2500 ° C. or higher and does not generate impurities at the sintering temperature is desirable. Furthermore, it is preferable to use a high-purity product with few impurities for the inert gas to be used.
[0045]
In the present invention, by performing the sintering step, a silicon carbide sintered body having excellent characteristics as a base material for a member for a semiconductor manufacturing apparatus can be obtained. From the viewpoint of increasing the density of the finally obtained sintered body. Therefore, a molding process described below may be performed prior to this sintering process. The molding process that can be performed prior to this sintering process will be described below. Here, the molding step is a process in which raw material powder obtained by homogeneously mixing silicon carbide powder and a nonmetallic sintering aid is placed in a molding die, and the temperature ranges from 80 to 300 ° C. In this step, the molded body is preliminarily adjusted by heating and pressurizing for 5 to 60 minutes. Here, the filling of the raw material powder into the mold is preferably performed as densely as possible from the viewpoint of increasing the density of the final sintered body. When this molding step is performed, a bulky powder can be made compact in advance when the sample is filled for hot pressing, and thus it becomes easy to produce a molded body having a large thickness by repeating this molding step.
[0046]
The heating temperature is 80 to 300 ° C., preferably in the range of 120 to 140 ° C., and the pressure is 60 to 100 kgf / cm, depending on the characteristics of the nonmetallic sintering aid.²In the range of 1.5 to 1.5 g / cm^ThreeOr more, preferably 1.9 g / cm^ThreeIt presses as mentioned above, and it hold | maintains for 5 to 60 minutes in a pressurized state, Preferably it is 20 to 40 minutes, and the molded object which consists of raw material powder is obtained. Here, the density of the molded body becomes difficult to increase as the average particle diameter of the powder decreases, and in order to increase the density, it is preferable to take a method such as vibration filling when placing in the molding die. . Specifically, a powder having an average particle diameter of about 1 μm has a density of 1.8 g / cm.^ThreeAs described above, the density of the powder having an average particle diameter of about 0.5 μm is 1.5 g / cm.^ThreeMore preferably. The density is 1.5 g / cm at each particle size.^ThreeOr 1.8 g / cm^ThreeIf it is less than this, it will be difficult to increase the density of the finally obtained sintered body.
[0047]
  This molded body can be cut so as to be compatible with a hot press die used in advance before being subjected to the next sintering step. This molded body was subjected to the above-mentioned temperature 2000-2400 ° C., pressure 300-700 kgf / cm.²A step of placing in a mold in a non-oxidizing atmosphere and hot pressing;SinteringA high-density, high-purity silicon carbide sintered body is obtained through the process.
[0048]
The silicon carbide sintered body produced as described above is sufficiently densified, and the density is 2.9 g / cm.^ThreeThat's it. The density of the obtained sintered body is 2.9 g / cm.^ThreeIf it is less than the range, the mechanical properties such as bending strength and fracture strength and the electrical physical properties are lowered, and further, the number of particles is increased and the contamination is deteriorated. The density of the silicon carbide sintered body is 3.0 g / cm.^ThreeMore preferably.
[0049]
In addition, if the obtained sintered body is a porous body, it is inferior in heat resistance, oxidation resistance, chemical resistance and mechanical strength, is difficult to clean, microcracks occur, and microscopic pieces become contaminants. In other words, it has inferior physical properties such as gas permeability and has problems such as limited use.
[0050]
  The total content of impurities in the sintered silicon carbide that can be used in the present invention isLess than 1ppmHowever, from the viewpoint of application to the semiconductor industry field, the impurity content by these chemical analyzes has only a meaning as a reference value. Practically, the evaluation differs depending on whether the impurities are uniformly distributed or locally distributed. Therefore, those skilled in the art generally use various means to evaluate how much impurities contaminate the wafer under a predetermined heating condition using a practical apparatus. A solid material obtained by homogeneously mixing a liquid silicon compound, a nonmetallic sintering aid, and a polymerization or crosslinking catalyst is heated and carbonized in a nonoxidizing atmosphere, and then further nonoxidized. According to the manufacturing method including the firing step of firing in a neutral atmosphere, the total content of impurity elements contained in the silicon carbide sintered body is 1 ppm.Less thanCan be. Here, the impurity element belongs to the group 1 to group 16 element in the periodic table of the 1989 IUPAC inorganic chemical nomenclature revised edition, and has an atomic number of 3 or more, and has atomic numbers of 6-8 and 14-16. An element excluding an element.
[0051]
In addition, when examining preferable physical properties of the silicon carbide sintered body according to the present invention, for example, the bending strength at room temperature is 50 to 65 kgf / mm.²Flexural strength at 1500 ° C is 55-80 kgf / mm²Young's modulus is 3.5 × 10^Four~ 4.5 × 10^Four, Vickers hardness is 2000kgf / mm²As described above, the Poisson's ratio is 0.14 to 0.21, and the thermal expansion coefficient is 3.8 × 10^-6~ 4.2 × 10^-6(℃^-1The thermal conductivity is preferably 150 W / m · k or more, the specific heat is 0.15 to 0.18 cal / g · ° C., the thermal shock resistance is 500 to 700 ΔT ° C., and the specific resistance is preferably 1 Ω · cm or less.
[0052]
The silicon carbide sintered body obtained by the above manufacturing method is subjected to processing such as processing, polishing, and washing according to the purpose of use, and a member for a semiconductor manufacturing apparatus is manufactured. As a processing method to a desired shape, electrical discharge machining utilizing conductivity is preferably used.
[0053]
The members and processing methods obtained by processing here will be specifically described. Examples of cutting out members from the material include straight line cutting with a wire electric discharge machine or diamond blade cutter, and curve cutting with a wire electric discharge machine. For drilling, round drilling with an electric discharge drilling machine or diamond grinding wheel grinding machine, bottomed hole / stepped drilling with a grinding machine or die-cutting electric discharge machine, irregular drilling with a wire electric discharge machine or die-sinking electric discharge machine, Screw hole drilling with a die-sinking electrical discharge machine or diamond tap machine, male thread machining with a cylindrical grinder or lathe using diamond electrodeposition tips, surface machining with a diamond grinding wheel surface grinder or lapping machine, with an electric discharge machine or shape grinder A grooving process etc. are mentioned. Since the silicon carbide sintered body which is a raw material of the member for a semiconductor manufacturing apparatus of the present invention has conductivity, it has an advantage that electric discharge machining with a wide machining range can be applied.
[0054]
As an electric discharge machine, for example, a die-sinking electric discharge machine, a wire electric discharge machine, an electric discharge drilling machine, etc., a general electric discharge machine for metal working can be used, but a power source is high for processing a material related to the member of the present invention. The output is easier to process and the processing time can be shortened. The power circuit has a built-in stable circuit, instantaneous maximum machining current of 50 amperes or more, maximum wire feed speed of 15 m / min. As described above, the use of a composite wire having a wire diameter of about 0.3 mm can be used as a guide. Moreover, it is not a spray type but a machining liquid immersion type.
[0055]
Depending on the sintered body used here, the jig can be formed integrally, but since the sintered body is homogeneous and highly pure, several parts are produced and assembled to form the jig. You can also. In the case of performing CVD processing, in order to form a uniform film, the jig is preferably integrally formed. When obtaining a complicated shape, as described above, the jig is complicated and various. However, if a part of the member is broken, the whole cannot be used. However, if the high-purity sintered body according to the present invention is used, various parts can be processed. Can be easily performed by known electric discharge machining, etc., and even if part of the part is damaged, it is easy to improve the advantage and surface accuracy (mirroring) that only the part can be replaced It also has advantages. The processing for forming the member into a desired shape can be performed by known machining procedures such as part cutting, drilling, screwing, manufacturing of fasteners such as bolts and nuts, and mirror finishing. The member for a semiconductor manufacturing apparatus thus obtained is used for parts of a semiconductor manufacturing apparatus, semiconductor safety parts, and the like.
[0056]
Here, as the main semiconductor manufacturing apparatus in which the semiconductor manufacturing apparatus member of the present invention is used, an exposure apparatus, a resist processing apparatus, a dry etching apparatus, a cleaning apparatus, a heat treatment apparatus, an ion implantation apparatus, a CVD apparatus, a PVD apparatus, Examples of parts include a plasma electrode for a dry etching apparatus, a protective ring (focus ring), a slit part (aperture) for an ion implantation apparatus, an ion generation unit, and a mass analysis unit. Examples include a protective plate, a dummy wafer used during wafer processing in a heat treatment apparatus or a CVD apparatus, and a heat generating heater in the heat treatment apparatus or the CVD apparatus, particularly a heater that directly heats the wafer in the lower portion thereof.
[0057]
In the production of a silicon carbide sintered body that is a material according to the present invention, as long as the heating conditions can be satisfied, the production apparatus is not particularly limited, and considering the pressure resistance of the sintering mold, A known heating furnace or a reaction apparatus can be used.
[0058]
Silicon carbide powder that is a raw material powder of the silicon carbide sintered body according to the present invention, a silicon source for producing the raw material powder, a non-metallic sintering aid, and further used for a non-oxidizing atmosphere The purity of each inert gas to be produced is preferably 1 ppm or less for each impurity element, but is not necessarily limited to this as long as it is within the allowable range of purification in the heating and sintering processes. Further, the impurity element here belongs to the group 1 to group 16 element in the periodic table of the 1989 IUPAC inorganic chemical nomenclature revised version, and has an atomic number of 3 or more, as described above. An element excluding the elements of atomic numbers 6-8 and 14-16.
[0059]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.
[0060]
Example 1
Manufacturing of compacts
High-purity silicon carbide powder (average particle size 1.1 μm: silicon carbide powder produced according to the production method described in JP-A-9-78605 and having an impurity content of 5 ppm or less: 1.5 wt% silica 90 g) and 10 g of high-purity liquid resol type phenolic resin with a water content of 20% (residual carbon ratio after thermal decomposition of 50%) dissolved in 150 g of ethanol are stirred for 18 hours with a planetary ball mill and mixed thoroughly. did. Thereafter, the mixture was heated to 50 to 60 ° C. to evaporate ethanol to dryness, and passed through a 500 μm sieve to obtain a homogeneous silicon carbide raw material powder. 8.5 g of this raw material powder was filled in a 30 mmφ mold and pressed at 130 ° C. for 20 minutes to obtain a density of 2.1 g / cm 2.^ThreeA molded body of was obtained.
[0061]
Production of sintered body
This compact was put into a graphite mold and hot pressed under the following conditions. As a hot press apparatus, a high-frequency induction heating type 10t hot press was used.
(Conditions for sintering process)
10^-Five-10^-FourUnder a torr vacuum condition, the temperature was raised from room temperature to 700 ° C. over 6 hours and held at that temperature for 5 hours. (First temperature raising step)
Under vacuum conditions, the temperature was raised from 700 ° C. to 1200 ° C. over 3 hours, further raised from 1200 ° C. to 1500 ° C. over 3 hours, and held at that temperature for 1 hour. (Second temperature raising step)
500 kgf / cm²Then, the temperature was increased from 1500 ° C. to 2200 ° C. in 3 hours under an argon atmosphere, and the temperature was maintained for 1 hour.
[0062]
(Hot press process)
The density of the obtained sintered body is 3.15 g / cm.^ThreeVickers hardness is 2300kgf / mm²The electrical resistivity was 0.02 Ω · cm. The metal impurities in this sintered body were all less than 0.1 ppm.
[0063]
Moreover, as a result of measuring the physical properties of the sintered body obtained in Example 1 in detail, as a property other than the above, the bending strength at room temperature was 57 kgf / mm.²Flexural strength at 1500 ° C is 60kgf / mm²Young's modulus is 4.1 × 10^FourPoisson's ratio is 0.15 and thermal expansion coefficient is 3.9 × 10^-6℃^-1The thermal conductivity was 200 W / m · k or more, the specific heat was 0.16 cal / g · ° C., and the thermal shock resistance was 530ΔT ° C., confirming that all of the above preferred physical properties were satisfied.
[0064]
Fabrication of components for semiconductor manufacturing equipment
The obtained sintered body was subjected to electric discharge machining to produce a member as shown in FIGS. 1 (A), (B), (C) and FIGS. 2 (A), (B), (C), (D). These were combined to produce a horizontal wafer boat as shown in FIG. FIG. 1A is a perspective view of a side plate 10 used for a horizontal wafer boat, and FIG. 1B is a perspective view of a support rod 12 used for a horizontal wafer boat having an outer diameter of 6 mm and a length of 600 mm having threaded portions at both ends. FIG. 1C shows a perspective view of the support column 14 attached to a plurality of locations to support the receiving rod 12. 2A shows a perspective view of the handle 16 attached to the bracket 18, FIG. 2B shows a perspective view of the bracket 18 attached to the side plate 10 shown in FIG. 1A, and FIG. FIG. 2D is a perspective view of the nut 20 used for coupling the side plate 10 and the support bar 12 and attaching the handle 16 and the like, and FIG. 2D is a perspective view of the bolt 22 for attaching the bracket 18 to the side plate 10. FIG. 3 is a schematic perspective view of the horizontal wafer boat 24.
[0065]
Evaluation of components for semiconductor manufacturing equipment
(Contamination)
A wafer (8 inches) was placed in this wafer boat, and an oxide film was formed on the surface of the wafer in a diffusion furnace at 1050 ° C. When the number of iron atoms within 1 μm from the surface in the oxide film was confirmed, 3.0 × 10¹²atoms / (1 μm × 1 cm²)Met. This indicates that the wafers are hardly contaminated, that is, the contamination of the wafer boat is negligibly small.
[0066]
(durability)
The obtained member was inserted into a diffusion furnace, heated to 1250 ° C. at a rate of 20 ° C./min in the presence of air, held at 1250 ° C. for 30 minutes, and then cooled to 800 ° C. at 15 ° C./min. The temperature raising and cooling cycle was repeated 10 times. Then, when the occurrence state of cracks, pinholes, etc. was visually observed on the surface of the member, occurrence of cracks, pinholes, etc. on the surface was not observed, and surface deterioration due to repeated heating and cooling was not seen. .
[0067]
(Solvent resistance)
After the weight of the obtained member was measured, it was washed 30 times with hydrofluoric acid, and the weight after washing was measured to determine the weight reduction. No decrease in weight was observed before and after washing, indicating that the solvent resistance was excellent.
[0068]
(Example 2)
Production of sintered body
8.5 g of silicon carbide raw material powder obtained in the same manner as in Example 1 was filled, pressed into the mold performed in Example 1, and pressed directly into a graphite mold without performing the step of obtaining a molded body. The powder was filled and hot pressed under the same conditions as in Example 1. As the hot press apparatus, the same one as in Example 1 was used.
(Hot press conditions)
10^-Five-10^-FourUnder a torr vacuum condition, the temperature was raised from room temperature to 700 ° C. over 8 hours and held at that temperature for 1 hour. (First temperature raising step)
Under vacuum conditions, the temperature was raised from 700 ° C. to 1200 ° C. over 3 hours, further raised from 1200 ° C. to 1500 ° C. over 3 hours, and maintained at that temperature for 4 hours. (Second temperature raising step)
500 kgf / cm²Then, the temperature was increased from 1500 ° C. to 2200 ° C. in 4 hours under an argon atmosphere, and the temperature was maintained for 1 hour. (Hot press process)
The density of the obtained sintered body is 3.05 g / cm.^ThreeVickers hardness is 2500kgf / mm²The electrical resistivity was 0.03 Ω · cm.
[0069]
Fabrication and evaluation of semiconductor manufacturing equipment components
Using the obtained sintered body, a member for a semiconductor manufacturing apparatus (wafer boat) was produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. As a result, the evaluation result of the contamination was 8 .3x10¹²atoms / (1 μm × cm²The contamination of the wafer boat was found to be negligibly small. Further, it was confirmed that the durability and solvent resistance were excellent as in Example 1.
[0070]
(Comparative Example 1)
After mixing 85% by weight of commercially available silicon carbide powder and 15% by weight of carbon powder to form the same member as in Example 1, it was placed in a calcining furnace and heated to 900 ° C. in a nitrogen gas atmosphere to be temporarily sintered. Got the body. Next, this was set in a sintering furnace, heated to 1550 ° C. and impregnated with metallic silicon, and sintering was completed. The sintered body thus obtained was cast and molded to obtain a wafer boat.
[0071]
The density of the obtained sintered body is 3.02 g / cm.^Three, Vickers hardness is 2000kgf / mm²The electrical resistivity is 1.0 × 10^-3It was Ω · cm.
[0072]
Evaluation of components for semiconductor manufacturing equipment
When the obtained semiconductor manufacturing apparatus member (wafer boat) was evaluated in the same manner as in Example 1, the contamination evaluation result was 1.1 × 10.¹⁶atoms / (1 μm × cm²It was found that the contamination was remarkable. As for durability, cracks occurred in the joint at the eighth temperature rise, and regarding solvent resistance, a 15% weight reduction was observed, and defects were observed in the wafer insertion part, resulting in durability and solvent resistance. Both were insufficient.
[0073]
(Comparative Example 2)
A silicon carbide film was formed on the surface of the wafer boat obtained by casting in Comparative Example 1 at 1000 ° C. using methyltrichlorosilane as a source gas by a CVD process. The thickness of the coating was 10 to 100 μm.
[0074]
Evaluation of components for semiconductor manufacturing equipment
The obtained semiconductor manufacturing apparatus member (wafer boat) was evaluated in the same manner as in Example 1. As a result, the contamination evaluation result was 4.6 × 10 6.¹²atoms / (1 μm × cm²) And the contamination was found to be negligibly small. As for durability, cracks were observed on the surface when the temperature was increased for the seventh time, and cracks were generated at the joint portion for the eighth time, resulting in insufficient durability. Regarding solvent resistance, no weight loss was observed even after washing with hydrofluoric acid, indicating that the solvent resistance was excellent.
[0075]
As is clear from the above-described examples and comparative examples, the semiconductor manufacturing apparatus members of Examples 1 and 2 obtained by the method of the present invention can be easily manufactured by combining parts by electric discharge machining and grinding. As a result, it was found that the durability and solvent resistance were excellent, and the contamination was negligibly small. On the other hand, the semiconductor manufacturing apparatus member of Comparative Example 1 obtained by the conventional method was insufficient in durability and solvent resistance, and the contamination was remarkable. In addition, the semiconductor manufacturing apparatus member of Comparative Example 2 in which a coating film was formed on the surface by CVD treatment was excellent in contamination and solvent resistance, but it was complicated to manufacture and was durable due to film strength problems. I found that there was a problem.
[0076]
Thus, since the member for a semiconductor manufacturing apparatus of the present invention exhibits excellent characteristics as an assembly-type member, the sintered body can meet the demand for a large-sized member accompanying the recent increase in size for a semiconductor manufacturing apparatus. It also shows the advantage that the manufacturing apparatus can be handled without increasing the size.
[0077]
【The invention's effect】
The semiconductor manufacturing apparatus member of the present invention is made of a high-quality silicon carbide sintered body having high density, high purity, high conductivity, and high thermal conductivity. There was no contamination of the semiconductor due to, and it had excellent durability and solvent resistance.
[Brief description of the drawings]
1A is a side plate used in a horizontal wafer boat obtained by electric discharge machining of a silicon carbide sintered body, FIG. 1B is a receiving rod, and FIG.
2A is a bracket handle used in a horizontal wafer boat obtained by electric discharge machining of a silicon carbide sintered body, and FIG. 2B is a side view of the bracket attached to the side plate shown in FIG. . (C) is a nut, and (D) is a side view of the bolt.
FIG. 3 is a schematic perspective view of a horizontal wafer boat of Example 1. FIG.

Claims (8)

A mixture of silicon carbide powder and a nonmetallic sintering aid, which is an organic compound that generates carbon by heating, is heated to 700 ° C. and held, and further heated to 1500 ° C. and held. After performing the second temperature elevation, a sintered body obtained by sintering by performing hot pressing in a non-oxidizing atmosphere at a temperature of 2000 to 2400 ° C., a pressure of 300 to 700 kgf / cm ² , A member for a semiconductor manufacturing apparatus, comprising a silicon carbide sintered body having a density of 2.9 g / cm ³ or more and a total content of impurity elements of less than 1 ppm.   The member for a semiconductor manufacturing apparatus according to claim 1, wherein the non-metallic sintering aid covers the surface of the silicon carbide powder.   The member for a semiconductor manufacturing apparatus according to claim 1, wherein the non-metallic sintering aid is silicon carbide powder having a surface coated with an organic compound that generates carbon by heating.   The semiconductor manufacturing apparatus member according to claim 1, wherein the non-metallic sintering aid is a resol type phenol resin.   5. The member for a semiconductor manufacturing apparatus according to claim 1, wherein the silicon carbide sintered body has a specific resistance of 1 Ω · cm or less.   The semiconductor manufacturing apparatus member according to claim 1, wherein the silicon carbide sintered body has a thermal conductivity of 200 W / m · k or more.   7. The semiconductor manufacturing apparatus member according to claim 1, wherein the semiconductor manufacturing apparatus member is an assembly-type member. A step of preparing a mixture of silicon carbide powder and a nonmetallic sintering aid that is an organic compound that generates carbon by heating, a first temperature raising step of heating and holding the mixture to 700 ° C., and A second temperature raising step for heating and holding up to 1500 ° C., and then a step of hot pressing in a non-oxidizing atmosphere at a temperature of 2000 to 2400 ° C., a pressure of 300 to 700 kgf / cm ² . A method for manufacturing a member for a semiconductor manufacturing apparatus.

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