WO2006080423A1

WO2006080423A1 - Monitor wafer and method for monitoring wafer

Info

Publication number: WO2006080423A1
Application number: PCT/JP2006/301289
Authority: WO
Inventors: Toshikazu Shinogaya; Akira Sato
Original assignee: Bridgestone Corporation
Priority date: 2005-01-31
Filing date: 2006-01-27
Publication date: 2006-08-03
Also published as: JPWO2006080423A1

Abstract

Disclosed is a monitor wafer characterized by being composed of a silicon carbide sintered body which has a recessed pocket in a monitor portion on the wafer surface for mounting a test piece. The monitor wafer is reusable and excellent in chemical resistance.

Description

Specification

MONITOR WAFER AND WAFER MONITORING METHOD

Technical field

The present invention relates to a monitor wafer and a wafer monitoring method. More specifically, the present invention relates to a monitor wafer having a carbon carbide sintered body strength and a wafer monitoring method using the monitor wafer.

Background art

In a conventional semiconductor manufacturing process such as LSI, silicon is used to confirm the deposition state of the deposited film formed on the wafer surface during the wafer surface processing step such as chemical vapor deposition (CVD) step. Powerful monitor wafers are used. Since such monitor wafers are expensive, they are reused by cleaning and removing the surface film with nitric acid after use.

[0003] However, since silicon has poor chemical resistance, when it is reused repeatedly, the silicon elutes and the surface becomes rough and cannot be used as a monitor wafer. Also, by re-polishing during reuse, the wafer becomes thinner, resulting in poor flatness, cracking, and automatic transfer. However, the means for improving the above-mentioned problem has been particularly apparent.

Disclosure of the invention

Means for solving the problem

That is, the present invention relates to the following description items:

(1) A monitor wafer characterized by having a carbonized carbon sintered body having a concave pocket for placing a test piece on a monitor portion on the wafer surface.

[0005] (2) a base wafer made of a sintered carbide carbide,

A ring plate that is detachably attached to the base wafer and forms a concave pocket for placing a test piece on the monitor portion when attached to the base wafer. Characteristic monitor wafer.

[0006] (3) The monitor wafer according to (1) or (2), further comprising a test piece that is detachably attached to the pocket. [0007] (4) The above test piece must have at least one of the requirements

Flatness 200 m or less,

Surface roughness (Ra) 0.1 l / z m or less,

The monitor wafer according to (3) above, wherein

(5) A monitor wafer body having a carbonized carbon sintered body having a concave pocket for mounting a test piece on a monitor portion on the wafer surface, and a test piece detachably attached to the pocket. A wafer monitoring method comprising: monitoring a deposited film deposited on the test piece using a monitor wafer having the same.

Brief Description of Drawings

[0009] [Fig. 1] Fig. 1 (a) shows a top view of a monitor wafer that works on the first embodiment, and Fig. 1 (b) shows a cross-sectional view of the monitor wafer that works on the first embodiment. FIG. 1 (c) is a partially enlarged view of the cross section of the monitor wafer according to the first embodiment.

[FIG. 2] FIG. 2 (a) is a top view of a monitor wafer that works on the second embodiment, and FIG. 2 (b) shows a cross-sectional view of the monitor wafer that works on the second embodiment. FIG. 4C is a partially enlarged view of a cross section of the monitor wafer according to the second embodiment.

[FIG. 3] FIGS. 3 (a) to 3 (d) show manufacturing process diagrams of a monitor wafer which is helpful in the first embodiment.

[FIG. 4] FIGS. 4 (a) to 4 (e) are diagrams showing a manufacturing process of a monitor wafer which is useful for the second embodiment.

[FIG. 5] FIG. 5 is a partially enlarged view of a cross section of a monitor wafer which is useful for the modification of the first embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] From the viewpoint of good chemical resistance to improve the conventional problems, the use of a monitor wafer that has carbon carbide strength has been studied. Powerful monitor wafers have improved the chemical resistance problem. However, since the carbon carbide has good chemical resistance, chemical mechanical polishing (CMP) treatment cannot be performed, and it has been extremely difficult to finish the surface flatness of a silicon wafer. Therefore, it was difficult to accurately grasp the deposition state of the deposited film deposited on silicon from the deposited film deposited on the carbide.

[0011] Therefore, as a result of further studies, the present inventors have found that the above-mentioned problems can be solved by making it possible to place a test piece on a monitor wafer body that also has a sintered carbide carbide strength. It was. Hereinafter, the present invention will be described with reference to embodiments. However, the present invention is not limited to the following embodiments!

[0012] (First embodiment)

The monitor wafer 10 that is effective in the first embodiment shown in FIGS. L (a) to (c) is made of a sintered carbide carbide having a concave pocket for placing a test piece on the monitor portion of the wafer surface. And a test piece 31 to 39 that is detachably attached to the pocket. The monitor wafer 10 has pockets 21 to 29 at positions where the test pieces 31 to 39 are attached.

The monitor wafer main body 2 is not particularly limited, but is formed by a hot press method, a CVD method, and a reactive sintering method. Hot press and CVD methods are preferred because of their good chemical resistance. In addition, the monitor wafer body 2 formed by a hot press method is more preferable in that the flatness during high-temperature processing is stable. The pockets formed in the form of dots on the wafer surface can be formed by a polishing method or the like.

[0014] The pocket can be provided without particular limitation as long as it is arranged in the monitor portion of the monitor wafer 10. In addition to the arrangement in the form of scattered dots, the monitor wafer 10 may be provided concentrically. The depth of the pocket is not particularly limited as long as the force can be appropriately changed depending on the thickness of the test pieces 31 to 39, and can be held to the extent that the test piece is not displaced at least during the CVD process.

As shown in FIG. 5, a through hole 61 may be provided at the bottom of the pocket of the monitor wafer 6. In that case, it is preferable to provide support portions 62a and 62b for holding the test piece 39.

[0016] The test pieces 31 to 39 are not particularly limited in thickness and shape as long as the state of the deposited film deposited on the surface can be monitored. The economic viewpoint is preferably thin. The shape may be a polygon such as a quadrangle in addition to a round shape. Examples of the material of the test piece include silicon, sapphire, graphite, and quartz. When mirror polishing, test pieces 31-39ί, flatness 200 μm or less, preferably 100 μm or less, surface roughness (Ra) 0.1 m or less, preferably 0.05 m or less, more preferably 0.02 m or less. The test pieces 31 to 39 may be reused by performing a cleaning process after monitoring. [0017] Since the monitor wafer main body 2 that exerts the power of the first embodiment also has the strength of sintered carbonized carbide, the chemical resistance is high and the test piece can be exchanged. Therefore, the monitor wafer body 2 can be reused any number of times by replacing the test pieces 31 to 39. In other words, the life of the monitor wafer 10 that is effective in the first embodiment is much longer than that of a monitor wafer that can be reused only about 4 times and also has a conventional silicon power. In addition, by simply changing the material of the test piece without replacing the material of the entire monitor wafer, it is possible to accurately determine the state of the deposited film of wafers of various materials and to know the force economically. Furthermore, the monitor wafer 10 which is useful for the first embodiment can be used in the same manner as a conventional monitor wafer. Therefore, the state of the deposited film on the wafer can be easily observed without the need for skilled techniques.

[0018] (Second Embodiment)

A monitor wafer 60, which is useful in the second embodiment shown in FIGS. 2 (a) to 2 (c), is a base wafer 3 made of a sintered carbide body, and is detachably attached to the base wafer 3. The ring plate 5 also has a carbon carbide sintered body force that forms a concave pocket for placing the test piece on the monitor portion, and the test piece 41 to be attached to the pocket itself. 49. The ring plate 5 has pockets 51 to 59 at positions where the test pieces 41 to 49 are attached. The following description will focus on differences from the first embodiment.

The base wafer 3 and the ring plate 5 are formed by a hot press method, a CVD method, or a reactive sintering method although there is no particular limitation. From the viewpoint of the stability of the flatness of the resulting monitor wafer, the hot press method is preferred. The wafer mounting surface of the base wafer 3 is preferably flat. This is because the stability of the test pieces 41 to 49 is improved by widening the contact surface between the test pieces 41 to 49 and the base cover 3 (the bottom of the pocket) when the wafer is placed. The flatness of the wafer mounting surface of the base wafer 3 is preferably about 10 μm to 50 μm. The holes formed in the ring plate 5 can be formed by an electric discharge machining method. The thickness of the ring plate 5, that is, the depth of the pocket, is a force that changes as appropriate according to the thickness of the test piece. ,.

[0020] The monitor wafer 60 that works in the second embodiment is that the ring plate 5 is the base wafer 3 or not. Therefore, the surface of the base wafer 3 can be easily polished. Therefore, the flatness of the wafer mounting surface of the base wafer 3 can be increased, and the stability of the test pieces 41 to 49 can be improved.

[0021] (Monitoring method)

As another aspect of the present invention, there is provided a wafer monitoring method using the monitor wafers 10 and 60, which is useful for the above embodiment. That is, a monitor wafer having a monitor wafer body having a carbonized carbide sintered body having a concave pocket for mounting a test piece on the monitor portion of the wafer surface and a test piece detachably attached to the pocket is used. Thus, there is provided a wafer monitoring method characterized by monitoring a deposited film deposited on the test piece.

[0022] (Monitor Wafer Manufacturing Method)

As an embodiment of the monitor wafer manufacturing method, a manufacturing method using a hot press method will be described. First, the hot press method will be described.

[0023] (Hot press method)

In the following, a method for producing a carbide used for producing a monitor wafer will be described. In the manufacturing method of the monitor wafer of this embodiment, a silicon carbide sintered body having a free carbon content of 2 to 10% by weight is used. Such a sintered carbonized carbide is obtained by firing a mixture of a sintered carbide powder and a nonmetallic sintering aid.

[0024] First, the carbon carbide powder will be described. As the carbide powder, α type, | 8 type, amorphous, or a mixture thereof can be widely used, and commercially available products may be used. Among these, β-type carbide powder is preferably used. In order to increase the density of the sintered carbide carbide, it is better that the particle size of the used carbide powder is small. Preferably it is about 0.01-10 micrometers, More preferably, it is 0.05-2 micrometers. When the particle size is less than 0.01 μm, handling in processing steps such as weighing and mixing becomes difficult. On the other hand, when the particle size exceeds 10 / zm, the specific surface area of the powder, that is, the contact area with the adjacent powder. Is not preferable because it becomes smaller and it is difficult to increase the density.

[0025] It is preferable to use a high-purity silicon carbide powder because the resulting sintered carbide body has high purity. High purity carbon carbide powder is, for example, a key compound (hereinafter referred to as “key source”). There is a case. ), An organic material that generates carbon by heating, and a polymerization catalyst or a cross-linking catalyst, and the obtained solid is fired in a non-oxidizing atmosphere. As a key source, at least one kind of liquid compound is used as a force capable of widely using liquid and solid compounds. Examples of the liquid key source include polymers of alkoxysilane (mono-, di-, tree, tetra). Among the alkoxysilane polymers, tetraalkoxysilane polymers are preferably used. Specifically, methoxysilane, ethoxysilane, propyloxysilane, butoxysilane and the like are mentioned. From the viewpoint of power handling, ethoxysilane is preferable. When the degree of polymerization of the tetraalkoxysilane polymer is about 2 to 15, a liquid low molecular weight polymer (oligomer) is formed. In addition, there are some liquid cation polymers having a high degree of polymerization. Examples of solid source that can be used in combination with a liquid source include carbide. Carbide carbides here include silica sol (including colloidal ultrafine silica) as well as mono-acid silicate (SiO) and diacid silicate (SiO 2).

2

Liquids containing colloidal molecules containing OH groups or alkoxy groups), fine silica, quartz powder, etc. are also included. Among these key sources, a tetraalkoxysilane oligomer having good homogeneity and a good ring ring property, or a mixture of an oligomer of tetraalkoxysilane and fine powder silica is preferable. In addition, these key sources are highly pure, and specifically, the initial impurity content is preferably 20 ppm or less, more preferably 5 ppm or less.

[0026] As the organic material that generates carbon by heating, in addition to a liquid material, a liquid material and a solid material may be used in combination. An organic material having a high residual carbon ratio and capable of being polymerized or crosslinked by a catalyst or heating is preferable. Specifically, monomers such as phenol resin, furan resin, polyimide, polyurethane, polybulal alcohol, and prepolymers are preferred. In addition, liquid materials such as cellulose, sucrose, pitch, and tar are also used. Among them, resole type phenolic resin is preferable in terms of thermal decomposability and purity. The purity of the organic material may be appropriately controlled according to the purpose. In particular, when high-purity silicon carbide powder is required, it is preferable to use an organic material having an impurity element content of less than 5 ppm each.

[0027] The mixing ratio of the source of the key and the organic material can be determined by intensifying a preferable range based on the molar ratio of carbon to key (hereinafter abbreviated as "CZSi"). What is CZSi here The czsi obtained from the elemental analysis of a carbonized carbon intermediate obtained by carbonizing a mixture of a key source and an organic material at 1000 ° C. As shown in the following reaction formula, carbon reacts with oxide silicon and changes to carbonized carbide.

[0028] Formula (I) SiO 2 + 3C → SiC + 2CO Therefore, in terms of stoichiometry, when CZSi is 3.0, the free carbon in the carbide intermediate is 0%. Since SiO gas etc. is volatilized, free carbon is generated even if czsi is lower. Since free carbon has an effect of suppressing grain growth, czsi should be determined according to the particle size of the target powder particles, and the key source and the organic material should be blended so as to obtain the ratio. For example, when calcining a mixture of a key source and an organic material at about 1 atm and 1600 ° C or higher, blending so that C / Si is in the range of 2.0 to 2.5, the free carbon Occurrence can be suppressed. Under the same conditions, when C / Si is compounded to exceed 2.5, free carbon generation becomes remarkable, and a carbonized carbon powder with small particles can be obtained. Thus, the blending ratio can be appropriately determined according to the purpose. In addition, since the action and effect of free carbon caused by the carbonized carbide powder are very weak compared with the action and effect of free carbon generated from the sintering aid, the free carbon caused by the carbonized carbide powder is The effect of this embodiment is not essentially affected.

[0029] A mixture of a key source and an organic material can be cured to form a solid. Curing methods include a method using a crosslinking reaction by heating, a method using a curing catalyst, and a method using electron beam or radiation. The curing catalyst to be used can be appropriately selected according to the organic material to be used. However, when phenol resin or furan resin is used as the organic material, such as toluenesulfonic acid, toluenecarboxylic acid, acetic acid, oxalic acid, hydrochloric acid, sulfuric acid, etc. Examples include acids and amines such as hexamine. Solids containing the key source and organic material are heated and carbonized as needed. Carbonization is performed by heating at 800 ° C to 1000 ° C for 30 to 120 minutes in a non-acidic atmosphere such as nitrogen or argon. Further, when heated at 1350 ° C. to 2000 ° C. in a non-oxidizing atmosphere, silicon carbide is generated. The firing temperature and firing time affect the particle size and the like of the resulting carbide powder, and may be appropriately determined. However, firing at 1600 to 1900 ° C. is efficient and preferable. The method for obtaining the high-purity silicon carbide powder described above is described in detail in the specification of JP-A-9-48605.

Next, the nonmetallic sintering aid will be described. Carbide carbide used in this embodiment The sintered body has a free carbon content of 2 to 10% by weight. This free carbon is attributed to the organic material used for the nonmetallic sintering aid, and the amount of free carbon can be reduced by adjusting the additive conditions such as the amount of nonmetallic sintering aid added. Can range.

[0031] As described above, a non-metallic sintering aid that can be a free carbon source, that is, an organic material that generates carbon by heating (hereinafter, sometimes referred to as "carbon source") may be used. . The above organic material may be used alone or as a sintering aid with the above organic material coated on the surface of a carbide powder (particle size: about 0.01 to 1 micron). From this point, it is preferable to use an organic material alone. Specifically, organic materials that generate carbon by heating include coal tar pitch, pitch tar, phenol resin, furan resin, epoxy resin, phenoxy resin, saccharides, which have a high residual carbonization rate, Examples thereof include monosaccharides such as darcos, small saccharides such as sucrose, polysaccharides such as cellulose and starch, and the like. In order to mix the organic material homogeneously with the carbonized carbide powder, the organic material is preferably liquid at room temperature, dissolved in a solvent, or softened by heating such as having thermoplasticity and heat melting properties. Of these, the use of phenol resin increases the strength of the sintered carbonized carbide, and is more preferably resol type phenol resin. Although the mechanism of operation of these organic materials is not clear, when organic materials are heated, inorganic carbon compounds such as carbon black and graphite are produced in the system. This inorganic carbon-based compound is considered to function effectively as a sintering aid. However, even if carbon black or the like is used as a sintering aid, the same effect cannot be obtained.

[0032] If desired, the nonmetallic sintering aid may be dissolved in an organic solvent, and the solution may be mixed with the silicon carbide powder. The organic solvent to be used varies depending on the non-metallic sintering aid. For example, when phenol resin is used as the sintering aid, lower alcohols such as ethyl alcohol, ethyl ether, acetone, etc. may be selected. it can. When producing high-purity silicon carbide sintered bodies, not only high-purity silicon carbide powder, but also sintering aids and organic solvents with low impurity content! Favored ,.

[0033] The amount of the nonmetallic sintering aid added to the carbide carbide powder is determined so that the free carbon of the sintered carbide carbide is 2 to 10% by weight. If the free carbon is outside this range, the chemical change to SiC that progresses during the bonding process, and the bonding between the sintered carbide bodies is insufficient. It becomes. Here, the free carbon content (% by weight) is determined by heating the sintered carbide carbide body in an oxygen atmosphere at 800 ° C for 8 minutes, and measuring the amount of generated CO and CO with a carbon analyzer.

2

The measured force can be calculated. The amount of sintering aid added varies depending on the type of sintering aid used and the amount of surface silica (silicon oxide) in the carbide powder. As a guideline for determining the addition amount, the amount of surface silica (silicon oxide) of the carbide powder is quantified using hydrogen fluoride water in advance, and the stoichiometry sufficient to reduce this oxide oxide ( Calculate the stoichiometry calculated by formula (I). In consideration of this and the rate at which the nonmetallic sintering aid generates carbon by heating, the amount added can be determined so that the free carbon falls within the above-mentioned suitable range. The description of the non-metallic sintering aid for the sintered carbide carbide described above is described in more detail in the specification of Japanese Patent Application No. 9-041048.

[0034] Next, a method for sintering a mixture of a carbide carbide powder and a nonmetallic sintering aid will be described. The silicon carbide powder and the nonmetallic sintering aid are mixed homogeneously. In order to obtain a homogeneous mixture, a solution obtained by dissolving a sintering aid in an organic solvent as described above may be used. Examples of the mixing method include known methods such as a method using a mixer, a planetary ball mill and the like. The equipment used for mixing is preferably a synthetic resin material in order to prevent metal element impurities from being mixed. Mixing is preferably performed for about 10 to 30 hours, particularly for about 16 to 24 hours, and mixed thoroughly. After thorough mixing, the solvent is removed and the mixture is evaporated to dryness. Thereafter, the mixture is sieved to obtain a raw material powder of the mixture. For drying, a granulator such as a spray dryer may be used.

[0035] The raw material powder thus obtained is placed in a molding die. It is preferable that the molding die to be used is made of graphite because metal impurities are not mixed in the sintered carbide body. Even in the case of a metal mold, the contact part is made of graphite so that the raw material powder and the metal part of the mold do not directly contact each other, or a polytetrafluoroethylene sheet (Teflon) is applied to the contact part. (Registered trademark) sheet) can be used preferably. In particular, when it is desired to produce a high-purity sintered carbonized carbon, it is preferable to use a high-purity graphite material for the mold and the heat insulating material in the furnace. Specifically, a graphite material or the like that is sufficiently baked at a temperature of 2500 ° C. or higher and does not generate impurities even when used at a high temperature can be used. The raw material powder placed in the molding die is subjected to hot pressing. Wide of Nag 300~700kgfZcm ² in particular constraints Te pressure Nitsuヽof the hot press, it can be carried out by the pressure of the range. However, when pressurizing at 400 kgfZcm ² or more, it is necessary to use hot press parts such as dies and punches having excellent pressure resistance.

Hot pressing is performed at a temperature of 2000 ° C to 2400 ° C. It is preferable that the temperature is raised to the hot pressing temperature gently and stepwise. When the temperature is raised in this way, chemical changes, state changes, etc. that occur at each temperature can be sufficiently advanced. As a result, it is possible to prevent the introduction of impurities, cracks and vacancies. An example of the temperature raising process is shown below. First, a molding die containing raw material powder is placed in a furnace, and the furnace is evacuated to 10 ^_4 torr. Gently raise the temperature from room temperature to 200 ° C and keep it at 200 ° C for about 30 minutes. Then, heat up to 700 ° C in 6-10 hours and keep at 700 ° C for 2-5 hours. In the temperature raising process from room temperature to 700 ° C, desorption of adsorbed moisture and organic solvent occurs, and carbonization of nonmetallic sintering aids also progresses. The holding time at the constant temperature varies depending on the size of the sintered carbonized carbide, and may be set to a suitable time as appropriate. In addition, the determination of force / force force with a sufficient holding time can be based on the time point when the degree of vacuum decrease is reduced to some extent. Next, the temperature is raised from 700 to 1500 until 6 to 9 hours and maintained at 1500 ° C for 1 to 5 hours. While the temperature is maintained at 1500 ° C., the reaction in which the oxide is reduced to carbon is progressed (formula (I)). Insufficient holding time is not preferable because silicon dioxide remains and adheres to the surface of the silicon carbide powder, thus preventing densification of the particles and causing large grains to grow. The determination of whether the holding time is sufficient is based on whether the generation of by-product carbon monoxide and carbon monoxide has stopped, i.e., the reduction in the degree of vacuum has stopped, and the reduction reaction start temperature has been reached. It can be used as a guideline to recover to a certain vacuum level of 1300 ° C.

The hot pressing is preferably performed after the inside of the furnace is heated to about 1500 ° C. at which sintering starts, and then filled with an inert gas in order to make the inside of the furnace a non-oxidizing atmosphere. As the inert gas, it is preferable to use argon gas that is non-reactive even at high temperatures, such as nitrogen gas or argon gas. If a high-purity silicon carbide sintered body is produced, use an inert gas with a high purity. After the furnace and non-oxidizing atmosphere, the temperature forces 2000 ^{^o} C~2400 ^o C, the furnace so that the pressure force S300~700kgf / cm ² Caro fever and Caro Press. If the maximum temperature is less than 2000 ° C, the densification is insufficient. On the other hand, if the maximum temperature exceeds 2400 ° C, it is not preferable because the powder or the raw material of the molded body may sublimate (decompose). It is preferable to raise the temperature from around 1500 ° C to the maximum temperature over 2 to 4 hours and hold at the maximum temperature for 1 to 8 hours. Sintering proceeds rapidly at 1850-1900 ° C and completes during the maximum temperature holding time. On the other hand, if the pressurization condition is less than 300 kgfZcm ² , the density increase is insufficient, and if it exceeds 700 kgfZcm ² , the graphite mold may be damaged, which is not preferable in terms of production efficiency. The surface roughness (Ra) is preferably 0 or less, and more preferably 0.2 μm or less. The pressure is preferably about 300 kgf / cm ^{2 to} 700 kgfZcm ^{2 in} order to suppress the growth of abnormal grains.

[0037] The sintered carbide carbide used is densified and has a density of 2.9 gZcm ³ or more and a porosity of 1% or less, preferably a density of 3. OgZcm ³ or more, and a porosity of 0.8% or less is particularly preferable. When a densified carbide body sintered body is used, mechanical properties such as bending strength and fracture strength, and electrical properties of the obtained bonded carbide body are improved. In addition, the use of a densified silicon carbide sintered body is preferable in terms of contamination because the constituent particles are reduced in size. On the other hand, if a low-density porous carbide sintered body, for example, is used, the heat resistance, oxidation resistance, chemical resistance, and mechanical strength of the carbonized carbon bonded body are inferior and the bonding strength is insufficient. Sometimes it becomes.

[0038] As a method for increasing the density of the sintered carbide carbide, there is a method in which a forming step is performed in advance of the sintering step. This molding process is performed at a lower temperature and lower pressure than the sintering process. By carrying out this sintering step, the bulky powder can be made compact (small volume) in advance, and by repeating this step many times, it becomes easy to produce a large molded body. An example of various conditions of the molding process performed in advance prior to the sintering process is shown below. The raw material powder obtained by homogeneously mixing the silicon carbide powder and the nonmetallic sintering aid is placed in a molding die, and the temperature is 80 ° C to 300 ° C, preferably 120 ° C to 140 ° C., pressure 50 kgfZcm 2 ˜: LOOkgfZcm ² is pressed for 5 to 60 minutes, preferably 20 to 40 minutes to obtain a molded body. The heating temperature may be appropriately determined according to the characteristics of the nonmetallic sintering aid. The density of the resulting molded product is 1.8 gZcm ² or more when using powder with an average particle size of about 1 m, and 1 when using powder with an average particle size of 0.5 m. Press to 5g / cm ² It is preferable to do this. If the density of the molded body to be used is within this range, it is preferable because it becomes easy to increase the density of the sintered carbide body. Cut the molded body so that the resulting molded body is compatible with the mold used in the sintering process.

[0039] Impurity elements in the sintered carbonized carbide used in this embodiment (in the element periodic table of the 1989 IUPAC inorganic chemical nomenclature revised edition, elements with atomic number 3 or more excluding C, N, 0, Si) If the total content of (element) is 5 ppm or less, it can be used for processes requiring high cleanliness, for example, semiconductor manufacturing processes. More preferably, it is 3 ppm or less, and particularly preferably 1 ppm or less. However, the impurity content by chemical analysis has only a meaning as a reference value in actual use. For example, even if the impurity content is the same, the evaluation of the contamination property of the carbide-bonded body may differ depending on the force that the impurities are uniformly distributed and whether the impurities are locally distributed. In addition, if the materials specifically exemplified above and the exemplified sintering method are used, a sintered carbide body having an impurity content of 1 ppm or less can be obtained. Moreover, in order to reduce the impurity element content of the sintered carbide body, the content of impurity elements contained in the raw materials used (for example, the carbide powder and non-metallic sintering aid) and the inert gas are used. For example, a method for removing impurities by adjusting the sintering conditions such as sintering time, temperature, etc. to 1 ppm or less. The impurity element here is the same as described above, and atomic number 3 or more in the periodic table of the 1989 IUPAC Inorganic Chemical Nomenclature Revision (except for C, N, 0, Si) This element.

[0040] Other physical properties of the sintered carbide carbide used in the present embodiment are: bending strength at room temperature 200 to 800 kgfZmm ² , Young's modulus 250 GPa to 500 GPa, Vickers hardness 2000 to 3500 kgfZmm ² , Poisson's ratio 0.14 to 0 21. Thermal expansion coefficient 3.8 X 10— ⁶ to 4.5 X 10— ⁶ 1 Z ° C, volume resistivity 0.1 Ω 'cm or less Various characteristics of the obtained carbonized carbide joint Is preferable. Incidentally, as the carbide carbide sintered body of the present embodiment, a carbide carbide sintered body described in the specification of Japanese Patent Application No. 9-041048 can be suitably used.

[0041] Further, it is preferable that the surface to be bonded of the sintered carbide body is smooth in terms of adhesion. Specifically, the surface roughness (Ra) of the surface to be bonded is 0.5 m or less. Preferred is 0.2 m or less. The surface roughness (Ra) of the sintered carbonized carbide should be adjusted to the above range by grinding or puffing with a 200 to 800 grinding wheel. Can do.

Next, silicon metal used as a bonding material will be described. The silicon metal used in the present embodiment is preferably one having a purity of 98% or more, more preferably 99% or more, and particularly preferably 99.9%. If silicon metal with low purity is used, a covalent compound due to an impurity element is generated in the carbide bonded body, and the fire resistance is lowered. In particular, when used in connection with semiconductor processes such as a wafer jig, it is preferable to use one having a purity of 99.999% or more. When the silicon metal used is a powder, the powder is preferably 100 mesh or more. If the size of the silicon metal is less than 100 mesh, the surfaces to be joined are liable to shift and dimensional accuracy cannot be obtained. There is no particular restriction on the upper limit, but what is actually available is less than 350 mesh.

The amount of silicon metal used for bonding affects the bonding strength and the like of the resulting silicon carbide bonded body. As a result of intensive studies by the present inventors, when the amount of silicon metal calculated in accordance with the following equation (1) is used, the bonding strength of the obtained silicon carbide bonded body is improved and the remaining silicon metal remains. It has been found that there is no reduction in the bonding strength or contamination due to. Formula (D k X {joint surface area (cm ² )} of carbon carbide bonded body} X {free carbon content of sintered carbide body (%)} (g) For example, when joining two sintered bodies with the same surface, the surface area is the projection surface of the surface of one sintered carbonized carbide. In addition, when 3 or more sintered carbide bodies are joined, the total surface area of the projected surfaces of all the joined surfaces of the sintered carbide body is summed to indicate the 1Z2 area. Where k is between 0.08 and 0.12, and is an experimentally determined coefficient whose dimension is g / cm ² Silicon metal is bonded to two or more sintered carbides For example, silicon metal powder is spread on the surface of one of the sintered carbide bodies, and then silicon metal Overlay the surface to which the other sintered carbide body is to be joined on the dispersed surface, or place two or more sintered carbide bodies in close proximity to each other so that a predetermined space can be obtained (the joining surfaces face each other). In this case, there is no need to pressurize in particular, for example, when bonding carbide carbide sintered bodies in a stacked state. If the weight of the sintered carbide body is only loaded, the surface should not be displaced. You may fix with a fixing tool or pressurize so that a surface may not shift. As a method of spraying silicon metal on the surface of the sintered carbide body, for example, there is a method using a funnel or the like so that the surface of the sintered carbide body is covered with silicon metal.

Next, the silicon carbide sintered body sandwiching the silicon metal is subjected to a high-temperature heat treatment. The heat treatment is preferably performed in a vacuum or in an inert gas atmosphere other than nitrogen gas, which is preferably performed in a non-acidic atmosphere. The inert gas used is preferably argon gas or helium gas. When nitrogen gas is used as an inert gas, it reacts with silicon metal at a high temperature to form nitride nitride, and the joint surface may be peeled off or broken due to a difference in thermal expansion. On the other hand, since argon gas and helium gas are non-reactive even at high temperatures, such problems do not occur and are preferable. In the case of manufacturing a high-purity silicon carbide bonded body, it is preferable to use a high-purity inert gas.

[0043] The heating temperature is preferably 1450 ° C to 2200 ° C as long as it is equal to or higher than the melting point of silicon metal. Below 1450 ° C, silicon metal does not melt, and at 2200 ° C, silicon metal partially sublimes. The upper limit is preferably 2000 ° C when j8 type carbide is used as the raw material, and 1800 ° C when α type is used. In particular, bonding at about 1600 ° C is preferable because a high-strength bonded body can be produced efficiently. Further, it is preferable to raise the temperature gently because the reaction between silicon metal and free carbon in the sintered carbonized carbon body proceeds sufficiently. Specifically, it is preferable to raise the temperature at 5 ° CZ to 15 ° CZ, especially about 10 ° CZ.

[0044] (Monitor wafer manufacturing process)

The monitor wafer 10 that works in the first embodiment is manufactured by the following process.

(Ii) A monitor wafer body 2 shown in FIG. 3 (a) is manufactured according to the hot press method. (Mouth) Next, as shown in FIG. 3 (b), pockets 24, 28, 29, 26, and 22 having a concave cross section are formed in the monitor portion of the monitor wafer body 2 using a polishing method.

(No.) Continue to embed the test specimens 34, 38, 39, 36, 32 in the pockets 24, 28, 29, 26, 22 as shown in Fig. 3 (c). As described above, the monitor wafer 10 that is effective in the first embodiment is manufactured. In addition, the monitor wafer 60 that is useful in the second embodiment is manufactured by the following steps.

(B) The base wafer 3 and the ring plate 5 constituting the monitor wafer 60 shown in FIG. 4 (a) are manufactured according to the hot press method.

(Mouth) Next, the wafer mounting surface of the base wafer 3 is polished so as to be flat.

[0047] (c) Subsequently, an opening (pocket) is formed in the ring plate 5 by using an electric discharge machining method so as to form a pocket when the wafer is attached to the base wafer 3 as shown in FIG. 4 (b). 54, 58, 59, 56, 5

2 is provided.

(2) Next, the ring plate 5 is fixed to the base wafer 3 using bolts.

[0049] (e) Continue, Fig. 4 (d) [As shown, this test piece 44, 48, 49, 46, 42 in the pocket 54, 58, 59

, 56, 52. As described above, the monitor wafer 60 which is effective in the second embodiment is manufactured.

[0050] By the above production method, a high-purity, high-density, high-toughness sintered carbonized carbide (monitor mono) can be obtained. In the above hot press method, any known reactor in the heating furnace can be used as long as the above-described heating conditions of the present embodiment can be satisfied.

[0051] The obtained monitor wafers 10 and 60 have a structure in which the amount of residual key is small and the carbide particles are uniformly dispersed. The monitor wafers 10 and 60 obtained according to the present embodiment have a density of 2.9 gZcm ³ or more, and mainly isotropic silicon particles having an average particle diameter of 2 ^ m-lO ^ m are uniformly dispersed. Has a structure. Therefore, it can be used as a structural member with small variations in density and the like. In general, if the density of the sintered body is less than 2.9 gZcm ³ , the mechanical properties such as bending strength and fracture strength and the electrical properties are lowered, and further, the particles are increased, resulting in poor contamination. Therefore, it can be said that the monitor wafer of this embodiment has good mechanical characteristics and electrical characteristics. The density of the monitor wafers 10 and 60 in a preferred embodiment is 3. OgZcm ³ or more.

[0052] The total impurity content of the monitor wafers 10 and 60 obtained in the present embodiment is less than lOppm, preferably less than 5 ppm, more preferably less than 3 ppm, and even more preferably less than lppm. In addition, after carbonizing a solid obtained by intimately mixing a liquid key compound, a non-metallic sintering aid, and a polymerization or crosslinking catalyst in a non-oxidizing atmosphere, the According to the manufacturing method including the firing step of firing in an acidic atmosphere, the total content of impurities other than silicon, carbon, and oxygen contained in the monitor wafers 10 and 60 can be less than lppm. it can. The nitrogen content of the monitor wafers 10 and 60 obtained in this embodiment is 150 ppm or more.

[0053] In addition, when considering preferable physical properties of the monitor wafers 10 and 60 obtained in the present embodiment, for example, the bending strength at room temperature is 400 MPa to 700 MPa, the Vickers hardness is ί or 1500 kgf / mm ² or more, and Poisson iti is 0. 14 ~ 0.21, thermal expansion coefficient ίMA 3. 8 X 10— ⁶ 〜4.5 X 10— ⁶ (.C—, thermal conductivity 150WZm'k or more, specific heat 0.60 ~ 0.70jZg 'K, the resistivity is 1 X 10 ^_1 Ωcm or less.

The monitor wafers 10 and 60 of the present embodiment obtained as described above preferably have the following physical properties:

The monitor wafers 10 and 60 have a volume resistance of 1 Q cm or less, and in a more preferred embodiment 0.5 Q cm to 0.05 Ωcm. Monitor wafers 10 and 60 have a total content of unavoidable elements other than silicon and carbon of monitor wafers 10 and 60, that is, impurity elements of less than 5 ppm. The monitor wafers 10 and 60 have a density of 2.9 gZcm ³ or more, and in a more preferred embodiment, 3.00 to 3.15 gZcm ³ . The monitor wafers 10 and 60 have a bending strength of 00 MPa or more, and in a more preferred embodiment, 500 MPa to 700 MPa.

[0055] The raw material powder of the present embodiment is a carbon carbide powder, a source for producing the raw material powder, a non-metallic sintering aid, and a non-oxidizing atmosphere. It is preferable that the purity of each inert gas is less than or equal to 1 ppm of each impurity element. If it is within the allowable range of purity in the heating and sintering process, it is not necessarily limited to this! /. Further, the base plate and the ring plate may be manufactured using, for example, a reactive sintering method without being limited to the hot press method.

[0056] This application is accompanied by a priority claim based on a Japanese patent application filed earlier by the same applicant, ie, # 112005-2 3583 (filing date 31 January 2005), This description is incorporated herein for reference.

Industrial applicability

[0057] According to the present invention, a reusable monitor wafer having good chemical resistance is provided.

Claims

The scope of the claims

[1] A monitor wafer characterized in that the carbonized carbon sintered body has a concave pocket for placing a test piece on the monitor portion of the wafer surface.

[2] a base wafer made of a sintered carbide carbide,

A ring plate made of a sintered carbide body that is detachably attached to the base wafer and forms a concave pocket for placing a test piece on the monitor portion when attached to the base wafer;

A monitor wafer characterized by comprising:

3. The monitor wafer according to claim 1 or 2, further comprising a test piece that is detachably attached to the pocket.

[4] The test piece has at least one requirement

Flatness 200 m or less,

Surface roughness (Ra) 0 l / z m or less,

The monitor wafer according to claim 3, wherein:

[5] A monitor wafer comprising a monitor wafer body having a carbon carbide sintered body having a concave pocket for placing a test piece on the monitor portion of the wafer surface, and a test piece detachably attached to the pocket. And monitoring the deposited film deposited on the test piece using the method.