JP4731368B2 - Vacuum chuck and vacuum suction device using the same - Google Patents

Description

  The present invention relates to a vacuum chuck for sucking and holding workpieces such as semiconductor wafers and glass substrates, and a vacuum suction apparatus using the same.

  Conventionally, a vacuum suction apparatus having a vacuum chuck for fixing a semiconductor wafer by vacuum suction on the suction surface to grind the back surface of the device forming surface of the semiconductor wafer, and grinding the semiconductor wafer A wafer grinding apparatus including a diamond wheel to be processed is used.

  The semiconductor wafer fixed to the suction surface by vacuum suction is ground with a diamond wheel, but a work-affected layer usually occurs on the processed surface. In recent years, due to the ultra-thinning of semiconductor wafers, the influence of the work-affected layer is relatively large, and in the process of forming a semiconductor element from the semiconductor wafer, the semiconductor element is likely to crack due to the influence of the work-affected layer The problem is becoming apparent.

  In recent years, in order to remove the work-affected layer, additional polishing by a dry polishing method has been proposed in which the back surface of the device formation surface of a semiconductor wafer is polished with, for example, a polishing cloth to which abrasive grains are attached. Initially, the vacuum suction device used in combination with the dry polish type wafer polishing device was diverted from the vacuum suction device using the alumina sintered body used in combination with the wafer grinding device as the adsorption member. Due to the low thermal conductivity of the sintered material, the resin film that was used to protect the device formation surface melts because the heat from the semiconductor wafer cannot be released sufficiently during grinding with the diamond wheel. There was a problem that the forming surface was damaged.

  In order to solve this problem, paying attention to the high thermal conductivity of silicon carbide, the following Patent Documents 1 and 2 propose a vacuum chuck using a silicon carbide sintered body as an adsorbing member.

  Specifically, in Patent Document 1, a disk-shaped mounting portion made of a porous body mainly composed of silicon carbide for vacuum-adsorbing a semiconductor wafer or a glass substrate, and a support for the mounting portion. A silicate glass, a borosilicate glass, etc. are apply | coated between the support parts which consist of a dense body which has silicon carbide as a main component, and a mounting part and a support part are joined by fuse | melting at 1100-1250 degreeC. A vacuum chuck has been proposed.

In Patent Document 2, a disk-shaped mounting portion made of a porous body mainly composed of silicon carbide that vacuum-adsorbs a semiconductor wafer or a glass substrate, and a dense body mainly composed of silicon carbide that supports the mounting portion. Al ₂ O ₃ , SiO ₂ , Na ₂ O—SiO ₂ , Na ₂ O—CaO—SiO ₂ , K ₂ O—CaO—SiO ₂ , K ₂ O—PbO— By inserting a glass in which a non-oxide ceramic powder is blended into components such as SiO ₂ , BaO—SiO ₂ —B ₂ O ₃ , Na ₂ O—B ₂ O ₃ —SiO ₂ , and melting at 1000 ° C., There has been proposed a vacuum suction chuck in which an air impervious layer that blocks air permeation is formed.
JP 2002-373873 A JP 2005-279789 A

  However, as proposed in Patent Document 1, a disk-shaped mounting portion made of a porous body mainly composed of silicon carbide and a dense body mainly composed of silicon carbide that supports the mounting portion. When the support made of silicate glass is to be joined with silicate glass, the melting temperature of silicate glass is 1700 ° C., so the silicate glass must be heated to this temperature.

  However, at this temperature, the placing portion and the supporting portion are oxidized, and bubbles are generated from the placing portion and the supporting portion along with this oxidation. And there is a problem that bubbles are likely to remain on the surface of the support part, and the bubbles become gaps to prevent the bonding, thereby reducing the bonding strength between the mounting part and the support part.

In addition, when the mounting part and the support part are joined with borosilicate glass, although the melting temperature is lower than that of silicate glass, alkali metal oxides such as Na ₂ O and K ₂ O are usually included in borosilicate glass. Therefore, during melting of the glass, these alkali metal oxides elute and adhere to the adsorption surface, and there is a problem that the vacuum-adsorbed semiconductor wafer or glass substrate is contaminated.

Moreover, as proposed in Patent Document 2, Na ₂ O—SiO ₂ , Na ₂ O—CaO—SiO ₂ , K ₂ O—CaO—SiO ₂ , K ₂ O—PbO—SiO ₂ , BaO—SiO _2. When glass containing a component non-oxide ceramic powder such as —B ₂ O ₃ , Na ₂ O—B ₂ O ₃ —SiO ₂ is used, it is difficult to cause shape change such as swelling, but as described above, alkali Since the metal oxide is contained, during the melting of the glass, these alkali metal oxides are eluted, adhere to the adsorption surface, and have a problem of contaminating the vacuum-adsorbed semiconductor wafer or glass substrate.

  Furthermore, when any glass proposed in Patent Document 1 and Patent Document 2 is used, it is melted at 1000 ° C. or higher, so that the mounting portion and the support portion are oxidized. Along with this oxidation, bubbles are generated from the mounting portion and the support portion, and there is a problem that the bubbles remaining on the surface hinder the bonding and lower the bonding strength between the mounting portion and the supporting portion.

  An object of the present invention is to provide a highly reliable vacuum chuck in which a semiconductor wafer and a glass substrate are prevented from being contaminated, and a mounting portion and a support portion are firmly bonded, and a vacuum suction device using the same. .

In view of the above, the present invention has the following configuration.

  Further, a mounting portion having an adsorption surface made of at least a porous body mainly containing silicon carbide and a supporting portion made of a dense body mainly containing silicon carbide that surrounds and supports the mounting portion are made of glass. In the vacuum chuck bonded with the shape of the bonding layer, the bonding layer is 30 to 65% by mass of Si, 10 to 40% by mass of Al, 10 to 20% by mass of B, and 4 to 5% by mass of Ca in terms of oxides. %, Mg 1 to 5 mass%, Ba 6 mass% or less (excluding 0 mass%), and Sr 5 mass% or less (excluding 0 mass%).

  Furthermore, the total ratio of heavy metal and alkali metal in the bonding layer is 300 ppm by mass or less (excluding 0 ppm by mass).

  Further, when the vacuum chuck is viewed in cross section, the ratio of the total length of the gaps between the support portion and the bonding layer to the total length of the interface between the support portion and the bonding layer is 45%. It is characterized by the following.

  Furthermore, the bonding strength between the mounting portion and the support portion is 40 kg · cm or more.

  Further, the bonding layer has a thickness of 5 to 100 μm.

  According to the vacuum chuck of the present invention, since glass can be melted at a low temperature of less than 1000 ° C., oxidation of each joint surface of the mounting portion and the support portion that has occurred in high-temperature bonding at 1000 ° C. or higher is suppressed. As a result, the generation of bubbles generated with oxidation is suppressed, and the placing portion and the support portion can be firmly joined.

  In addition, since the amount of these contaminants flowing out from the bonding layer is significantly reduced, it becomes difficult to contaminate the semiconductor wafer and the glass substrate.

  In addition, by controlling and managing bonding at an appropriate temperature with respect to the softening temperature of the glass, the gap of the bonding layer bonded to the support portion in a vertical cross section with respect to the suction surface of the mounting portion for vacuum suction of the semiconductor wafer or the glass substrate The ratio of the length of the portion is set to 45% or less, and the unbonded portion between the support portion and the bonding layer is reduced, so that the bonding strength between the placement portion and the support portion can be increased.

  Further, if the bonding strength between the mounting portion and the supporting portion is 40 kg · cm or more, the mounting portion can be polished even if this surface is polished in order to maintain the flatness of the surface that vacuum-sucks the semiconductor wafer or the glass substrate. Since it will not be detached from the support portion, the reliability can be increased.

  Further, since the bonding layer is made of glass, the thermal conductivity is lower than that of the mounting portion made of a porous body mainly composed of silicon carbide or the supporting portion made of a dense body mainly composed of silicon carbide. Therefore, especially when the thickness of the bonding layer is as thin as 5 to 100 μm, it is possible to efficiently dissipate heat from the support portion without stagnation of heat.

  In addition, the vacuum suction device of the present invention uses the vacuum chuck in which the mounting portion and the support portion are firmly joined as the suction member, and thus is highly reliable and suitable.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  1A and 1B show an embodiment of a vacuum chuck according to the present invention, in which FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view taken along line AA in FIG.

  The present invention provides a mounting portion having an adsorption surface made of a porous body mainly composed of silicon carbide, and a supporting portion made of a dense body mainly composed of silicon carbide that surrounds and supports the mounting portion. Are bonded to each other by a glass-like bonding layer, and the bonding layers are 30 to 65% by mass of Si, 10 to 40% by mass of Al, 10 to 20% by mass of B and 4 to 20% of Ca in terms of oxides. It is important to contain -5 mass%, Mg 1-5 mass%, and Ti 5 mass% or less (except 0 mass%).

  Alternatively, the mounting portion having an adsorption surface made of at least a porous body mainly composed of silicon carbide and the supporting portion made of a dense body mainly composed of silicon carbide that surrounds and supports the mounting portion is made of glass. In the vacuum chuck bonded with the shape of the bonding layer, the bonding layer is 30 to 65% by mass of Si, 10 to 40% by mass of Al, 10 to 20% by mass of B, and 4 to 5% by mass of Ca in terms of oxides. %, Mg is 1 to 5 mass%, Ba is 6 mass% or less (excluding 0 mass%), and Sr is 5 mass% or less (excluding 0 mass%).

For example, the bonding layer SiO ₂ is 30 to 65 wt%, _Al 2 _{O 3} is 10 to 40 _wt%, B 2 _{O 3} is 10 to 20 mass%, CaO 4 to 5 wt%, MgO 1 to 5 For example, a glass having 0 to 5% by mass of TiO ₂ , 0 to 6% by mass of BaO, and 0 to 5% by mass of SrO.

  The vacuum chuck 1 of the present invention mainly includes a mounting portion 2 made of a porous body mainly composed of silicon carbide that vacuum-adsorbs a semiconductor wafer or a glass substrate, and silicon carbide that surrounds and supports the mounting portion 2. A support 3 made of a dense body as a component is joined by a glassy bonding layer 4.

  The mounting part 2 is a porous body having a disk shape and a three-dimensional network structure in which pores 2a that perform adsorption are continuous, and high thermal conductivity and mechanical characteristics are required. The main component. Then, a semiconductor wafer or a glass substrate (both not shown) is placed on the suction surface 2b of the mounting portion 2, and is fixed by being sucked through the pores 2a by a vacuum pump (not shown). Yes.

  The support portion 3 is a substantially disk-shaped dense frame having a circular recess 3a in the center, and the mounting portion 2 is fixed and supported in the recess 3a by a bonding layer 4 made of glass. Like the mounting portion 2, silicon carbide is the main component because high thermal conductivity and mechanical properties are required.

  In addition, the main component in this invention means the component which occupies 70 mass% or more among the components which comprise the mounting part 2 and the support part 3, Preferably it occupies 75 mass% or more.

  The suction surface 2b of the mounting portion 2 and the top surface 3b of the partition wall forming the concave portion 3a of the support portion 3 are configured to be located on the same plane, and the suction surface 2b maintains flatness. It is polished according to the frequency of use. A suction passage 3c communicating with the pores 2a is formed inside the support portion 3, and serves as an exhaust passage. A flange portion 3d is provided on the outer peripheral edge of the support portion 3, and the flange portion 3d is attached to various devices by means such as screwing or engagement.

Of the glass components, SiO ₂ is the main component for forming the glass skeleton,
When the content of SiO ₂ is too small, the weather resistance may decrease, the thermal expansion coefficient may become large. On the other hand, when the content of SiO ₂ is too large, the meltability is deteriorated and tridymite or cristobalite is easily devitrified as a foreign substance in the binder phase.

In the present invention, by setting the ratio of SiO _{2 in} the binder phase to 30 to 65% by mass, it is possible to reduce the difference between the thermal expansion coefficient of glass and the thermal expansion coefficient of silicon carbide without reducing the weather resistance. At the same time, devitrification of tridymite and cristobalite can be prevented.

Al ₂ O ₃ is a component that increases the heat resistance and devitrification resistance of the glass. If the content of Al ₂ O ₃ is too small, the heat resistance of the glass is reduced, or foreign matter due to devitrification is generated. To do. Conversely, when the content of Al ₂ O ₃ is too large, the melting property of the glass is lowered.

In the present invention, by setting the ratio of Al ₂ O _{3 in} the binder phase to 10 to 40% by mass, it is possible to prevent the occurrence of foreign matters due to devitrification without lowering both weather resistance and meltability.

B ₂ O ₃ is a component that acts as a flux, lowers the viscosity, and improves the meltability of the glass. If the content of B ₂ O ₃ is too small, the meltability cannot be sufficiently improved, If it is too high, chemical durability may be reduced or foreign matter may be generated due to devitrification.

In the present invention, the ratio of B ₂ O _{3 in} the binder phase is 10 to 20% by mass, thereby improving the meltability of the glass and at the same time maintaining the chemical durability and preventing the generation of foreign substances due to devitrification can do.

  CaO is a component that lowers the high-temperature viscosity without lowering the strain point, improves the meltability of the glass, or adjusts the thermal expansion coefficient. If the CaO content is too small, the thermal expansion coefficient increases. When there is too much content of CaO, the foreign material by devitrification will generate | occur | produce.

  In the present invention, by setting the CaO ratio in the binder phase to 4 to 5% by mass, the difference between the thermal expansion coefficient of glass and the thermal expansion coefficient of silicon carbide can be reduced, and foreign matter caused by devitrification can be reduced. Occurrence can be prevented.

MgO is also a component that lowers the high temperature viscosity without lowering the strain point, improves the meltability of the glass, and adjusts the thermal expansion coefficient. If the MgO content is too small, the thermal expansion coefficient will increase. When the content of MgO is too large, enstatite (MgO.SiO ₂ ) is generated as a foreign matter due to devitrification.

In the present invention, by setting the MgO ratio in the binder phase to 1 to 5% by mass, the difference between the thermal expansion coefficient of glass and the thermal expansion coefficient of silicon carbide can be reduced, and enstatite (MgO · Generation of SiO ₂ ) can be prevented.

TiO ₂ is a component that improves the mechanical strength of the glass, but if it is too much, foreign matter due to devitrification tends to be generated.

In the present invention, by including 5 mass% or less of the TiO ₂ ratio in the binder phase, it is possible to improve the mechanical strength of the glass and prevent the generation of foreign substances due to devitrification.

However, it is necessary that TiO ₂ does not contain 0 but contains an inevitable amount.

Alternatively, instead of TiO ₂ , SrO and BaO are components that improve the chemical resistance of the glass and improve the meltability of the glass, but if too much, the meltability is impaired and melting defects occur.

  In the present invention, the meltability of the glass can be improved without causing melting defects by setting the BaO ratio in the binder phase to 0 to 6 mass% and the SrO ratio to 0 to 5 mass%. .

  However, BaO and SrO do not include 0, and it is necessary that an inevitable amount is included.

  Furthermore, since the glass is melted at a low temperature of less than 1000 ° C. by setting the glass to such a composition and ratio, each of the mounting portion 2 and the support portion 3 that has occurred in the high-temperature bonding at 1000 ° C. or higher. Oxidation of the joint surface is suppressed. As a result, the generation of bubbles generated with oxidation is suppressed, and the mounting portion 2 and the support portion 3 can be firmly joined.

  In addition, what is necessary is just to obtain | require each ratio of a metal by ICP (Inductivity Coupled Plasma) emission analysis method, and to just convert each ratio of the glass component which comprises the coupling layer 4, respectively.

  Furthermore, the ratio of heavy metals or alkali metals in the tie layer is preferably 300 ppm by mass or less (excluding 0 ppm by mass).

  Here, the heavy metal means a heavy metal having a specific gravity of 4 or more (excluding Ti), and the alkali metal contains an oxide.

  Moreover, since the heavy metal (however, except Ti), the alkali metal, and the oxide of these metals in the coupling layer 4 become a contamination source of a semiconductor wafer or a glass substrate, the fewer the better.

  By setting the ratio of heavy metal and alkali metal in the bonding layer to 300 ppm by mass or less, even if the heavy metal and alkali metal evaporated from the bonding layer 4 diffuse into the semiconductor wafer, the semiconductor element formed from the semiconductor wafer is erroneous. Does not cause operation.

  However, when the crystal structure of the bonding layer 4 is analyzed using an X-ray diffraction method, a compound showing an intensity peak but not identifiable is not included in the total ratio.

In particular, the thermal expansion coefficient of the bonding layer 4 is preferably close to the thermal expansion coefficient of silicon carbide or silicon. For example, the thermal expansion coefficient is preferably 3.0 to 4.7 × 10 ⁻⁶ / ° C. It is.

  Further, when the vacuum chuck is viewed in cross section, the ratio of the total length of the gaps between the support portion and the bonding layer to the total length of the interface between the support portion and the bonding layer is 45%. It is characterized by the following.

  The ratio of the length of the gap portion of the bonding layer 4 joined to the support portion 3 in the vertical cross section to the suction surface 2b of the placement portion 2 that vacuum-sucks the semiconductor wafer or the glass substrate is the placement portion 2, the support If the ratio increases, the bonding strength decreases, and if the ratio decreases, the bonding strength increases.

  In the present invention, by setting the ratio to 45% or less, the unbonded portion between the support portion 3 and the bonding layer 4 is reduced, so that the bonding strength between the placement portion 2 and the support portion 3 can be increased. it can.

  FIG. 2 schematically shows the gap 4 a of the bonding layer 4 joined to the support 3, and is a cross-sectional view seen from a direction perpendicular to the thickness direction of the vacuum chuck 1. The ratio of the length of the portion 4a is defined as (the length of the gap portion 4a / (the length of the gap portion 4a + the length of the joint portion 4b) × 100) (%), and in FIG. 2, (a1 + a2 +... + A11) / ((a1 + a2 +... + A10) + (b1 + b2 +... + B11)) × 100.

  The ratio of the length of the gap 4a is, for example, that the total of the length of the gap 4a and the length of the joint 4b is 0.3 to 0 from an image obtained at a magnification of 100 to 500 using a scanning electron microscope. What is necessary is just to obtain | require in the range which becomes .9mm.

  Furthermore, it is preferable that the bonding strength between the mounting portion and the support portion is 40 kg · cm or more.

  Further, the bonding strength between the mounting portion 2 and the support portion 3 affects the reliability of the vacuum chuck 1.

  Even if the suction surface 2b is polished in order to maintain the flatness of the suction surface 2b by setting the bonding strength between the placement portion 2 and the support portion 3 to 40 kg · cm or more, the placement portion 2 supports the support portion 3. Since there is no such thing as deviating from the above, reliability can be improved.

  For the bonding strength, a 10 mm × 10 mm × 30 mm test piece sandwiching the bonding layer 4 in the center in the longitudinal direction is cut out from the vacuum chuck 1, and after fixing the porous body, the dense body is twisted with a torque wrench. The strength when the test piece breaks is read, and this value may be used as the bonding strength.

  By the way, since the bonding layer 4 is made of glass, the thermal conductivity is higher than the mounting portion 2 made of a porous body mainly composed of silicon carbide and the support portion 3 made of a dense body mainly composed of silicon carbide. Lower.

  Therefore, in order to improve the heat dissipation of the vacuum chuck 1, it is preferable to reduce the thickness of the binder phase 4. In the present invention, the thickness is preferably set to 100 μm or less. This is because by reducing the thickness of the bonding layer 4 to 100 μm or less, it is possible to efficiently dissipate heat from the support portion without delaying heat transfer.

  However, if the thickness of the bonding layer 4 is made too thin, the anchor effect of the glass on the placement portion 2 is reduced, so that the thickness is preferably 5 μm or more.

  In addition, the thickness of the binder phase 4 can be calculated | required from the image of 100-500 times of magnification obtained with a scanning electron microscope.

  Next, the manufacturing method of the vacuum chuck of this invention is demonstrated.

  In order to obtain the mounting portion 2 constituting a part of the vacuum chuck 1 of the present invention, first, silicon powder having an average particle diameter of 1 to 90 μm with respect to 100 parts by weight of α-type silicon carbide powder having an average particle diameter of 105 to 350 μm. A thermosetting resin such as a phenol resin, an epoxy resin, a furan resin, a phenoxy resin, or a melamine is prepared by blending 15 to 30 parts by weight and having a residual carbon ratio after the subsequent degreasing treatment of 30% or more as a molding aid. At least one of resin, urea resin, aniline resin, unsaturated polyester resin, urethane resin, and methacrylic resin is added and mixed uniformly with a ball mill, vibration mill, colloid mill, attritor, high-speed mixer, or the like. In particular, a resol-type or novolac-type phenol resin is suitable as the molding aid from the viewpoint of low shrinkage after thermosetting.

  Since the amount of the molding aid added affects the green density of the molded body, it also strongly affects the porosity of the mounting portion 2. In order to set the porosity of the mounting portion 2 to 30 to 40%, the additive amount of the molding aid may be 1 to 2 parts by weight with respect to 100 parts by weight of the α-type silicon carbide powder.

  By the way, α type and β type exist in silicon carbide, and generally α type has higher oxidation resistance than β type, and hardly contains residual carbon and residual silicon inside the particle. For this reason, α-type silicon carbide is used as a starting material.

  In addition, it is important that the average particle diameter of the α-type silicon carbide powder is 105 to 350 μm. When the average particle diameter is 105 μm or less, the powder having a small diameter forms closed pores or the pores themselves are reduced. Thus, when vacuum-sucking a semiconductor wafer or a glass substrate, the pressure loss increases. On the other hand, when the thickness exceeds 350 μm, the density of the mounting portion 2 decreases, and the strength decreases. By setting the average particle size of the α-type silicon carbide powder to 105 to 350 μm, it is possible to obtain the placement portion 2 that has low pressure loss and does not cause a decrease in strength.

  Further, the silicon powder becomes a silicon phase in the subsequent heat treatment, and connects the silicon carbide crystal particles. As the silicon powder, it is important to use a powder having an average particle diameter of 1 to 90 μm and a ratio of 15 to 30 parts by weight with respect to 100 parts by weight of the α-type silicon carbide powder. This is because if the average particle size of the silicon powder is less than 1 μm, the dispersibility of the silicon powder is poor and the silicon carbide crystal particles can be connected only locally.

  On the other hand, if it exceeds 90 μm, the silicon powder will melt and move so as to cover the silicon carbide powder in the subsequent heat treatment, so that the space where the silicon powder is partially aggregated and occupied remains as large pores, This is because it causes a decrease.

  Moreover, the ratio of silicon powder to 15 to 30 parts by weight with respect to 100 parts by weight of α-type silicon carbide powder is that when the ratio of silicon powder is less than 15 parts by weight, the ratio of silicon carbide to crystal particles is low, This is because crystal grains cannot be sufficiently connected.

  On the other hand, when the ratio exceeds 30 parts by weight, silicon is easily segregated, the ratio of silicon carbide having relatively good mechanical characteristics is lowered, and sufficient mechanical characteristics cannot be obtained. By setting the ratio of the silicon powder to 15 to 30 parts by weight, it is possible to obtain a placement part having a homogeneous structure with sufficient mechanical characteristics.

  Note that the purity of the silicon powder is desirably high, that having a purity of 95% or more is preferable, and the use of high-purity silicon having a purity of 99% or more is particularly preferable. In addition, the shape of the silicon powder to be used is not particularly limited, and not only a spherical shape or a shape close thereto, but also an irregular shape can be suitably used.

  Each average particle diameter of the silicon carbide powder and the silicon powder can be measured by a liquid phase precipitation method, a light dropping method, a laser scattering diffraction method, or the like.

  Next, the mixed raw material is granulated using various granulators such as a rolling granulator, a spray dryer, a compression granulator, an extrusion granulator. In particular, in order to obtain granules having a large particle size, for example, granules having a particle size of 0.4 to 1.6 mm, it is preferable to use a rolling granulator.

  The granulation time is preferably 30 minutes or longer in consideration of the crushability of the compact.

  In addition, the particle size of the granules obtained by this granulation is preferably 0.4 to 1.6 mm, and even if the particle size is less than 0.4 mm or exceeds 1.6 mm, the crushability of the molded product is deteriorated, Although handling becomes difficult, the collapsibility of a molded object and handling improve by making the particle size of a granule into 0.4-1.6 mm. In particular, the particle size of the granules is preferably 0.5 to 1.5 mm.

  Next, the granules are formed into a desired shape by a molding means such as dry pressure molding or cold isostatic pressing, and if necessary, non-condensed such as argon, helium, neon, nitrogen, vacuum, etc. After performing a degreasing treatment at 400 to 600 ° C. in an oxidizing atmosphere, a silicon-silicon carbide composite can be obtained by heat treatment at 1400 to 1450 ° C. in a non-oxidizing atmosphere as in the degreasing treatment.

  In order to lower the temperature of the heat treatment, the purity of silicon is preferably 99.5 to 99.8% by mass.

  In the heat treatment, it is important to set the temperature to 1400 to 1450 ° C. If the temperature is lower than 1400 ° C, the silicon powder is not sufficiently melted, so that silicon carbide crystal particles cannot be connected as a silicon phase. This is because the silicon tends to cause a decrease in strength due to the evaporation of silicon, and the manufacturing cost increases. By setting the heat treatment temperature to 1400 to 1450 ° C., the silicon powder is appropriately melted without evaporating, so that a cavity is interposed between adjacent silicon carbide crystal particles, and two or more joints are generated. In addition, the silicon carbide crystal particles can be connected as a silicon phase, appropriate strength and thermal conductivity can be obtained, and the manufacturing cost can be reduced. In particular, the heat treatment temperature is preferably set to 1420 to 1450 ° C., and by performing heat treatment in this temperature range, a composite having a three-point bending strength of 30 MPa or more and a Young's modulus of 30 GPa or more can be obtained. Also, in order to coat silicon carbide crystal particles with silicon, the silicon powder must be sufficiently melted, and then the silicon will evaporate or react with the carbon floating in the atmosphere and change to silicon carbide. There must be no. In order to coat silicon carbide crystal particles with silicon from such a viewpoint, the temperature may be set to 1420 to 1440 ° C.

  The composite body obtained by such a manufacturing method can be used as the mounting portion 2 by subjecting the upper surface thereof to machining such as grinding and polishing.

  The suction surface 2b needs to be flattened as much as possible because the surface state affects the accuracy of the processed semiconductor wafer or glass substrate. The flatness should be at least 1 μm or less, preferably 0.3 μm or less. It is desirable.

Next, the support part 3 which is a substantially disk-shaped dense frame body which has silicon carbide as a main component and has a circular recess 3a in the center is prepared, and SiO ₂ is 30 to 65 mass%, and Al ₂ O ₃ is 10 to 40 _wt%, B 2 _{O 3} is 10 to 20 mass%, CaO 4 to 5 wt%, MgO 1 to 5 wt%, TiO ₂ is 0 to 5 wt%, BaO 0 to 6% by weight and Paste glass composed of 0 to 5% by mass of SrO is applied to the recesses 3a. After the glass application, the mounting portion 2 is placed in the concave portion 3a and pressed from the thickness direction by a dedicated pressurizing device. After the pressurization, the mounting portion 2 and the support portion 3 are bonded by the bonding layer 4 made of glass by heat treatment at 950 to 980 ° C., and the vacuum chuck of the present invention can be obtained.

  When such a vacuum chuck is used as an adsorbing member in a vacuum adsorbing device provided with a vacuum pump (not shown) that exerts an adsorbing action on an object to be processed via the suction passage 3c, for example, the mounting portion 2 and the supporting portion 3 are used. Are firmly bonded to each other, which is preferable because of high reliability.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

(Example 1)
First, α-type silicon carbide powder, silicon powder, and a phenol resin as a molding aid were uniformly mixed to prepare a blended raw material. This blended raw material was put into a tumbling granulator to form granules, and a molded body was obtained by dry pressure molding.

  Next, this molded body was degreased at 500 ° C. in a nitrogen atmosphere and then heat-treated at 1420 ° C. in the same nitrogen atmosphere to obtain a porous body having a porosity of 31% and an average pore diameter of 55 μm, as shown in FIG. The mounting part 2 was produced.

  The porosity of the mounting portion 2 and the average diameter of the pores 2a were measured in accordance with Archimedes method and JIS R 1655-2003 defined in JIS R 1634-1998, respectively.

  Next, the support part 3 which is a substantially disk-shaped dense frame having silicon carbide as a main component and having a circular recess 3a in the center is prepared, and each component of the glass constituting the bonded layer 4 after bonding is prepared. The paste-like glass adjusted so as to become Table 1 was apply | coated to the recessed part 3a. After applying the glass, the mounting portion 2 is placed in the concave portion 3a, pressed in the thickness direction with a dedicated pressurizing device, and then heat treated at 980 ° C. to obtain a vacuum chuck having a bonding layer thickness of 110 to 120 μm. It was.

  And the ratio of each component of the glass which comprises the coupling layer 4 calculated | required each ratio of the metal by ICP (Inductivity Coupled Plasma) emission spectrometry, and each converted it into oxide.

  Further, the thermal expansion coefficient of the glass was separately measured in accordance with JIS R 3102-1995.

  Regarding the bonding strength between the mounting part 2 and the support part 3, after cutting out a 10 mm × 10 mm × 30 mm test piece sandwiching the bonding layer 4 in the center in the longitudinal direction and fixing the porous body, the dense body with a torque wrench. The strength when the test piece was broken was read, and this value was defined as the bonding strength.

  These measurement results are shown in Table 1.

Regarding the foreign matter due to devitrification, the cross section of the bonding layer 4 was observed at a magnification of 500 times using a scanning electron microscope.

As shown in Table 1, a sample No. having SiO ₂ of less than 30% by mass was obtained. 7, Sample No. whose CaO is less than 4% by mass. 2, sample No. 1 with MgO less than 1% by mass. Since No. 1 had a high thermal expansion coefficient of 5.3 × 10 ⁻⁶ / ° C. or more, the shrinkage of the glass during cooling was larger than that of the mounting portion and the supporting portion. As a result, a void portion was generated in the bonding layer 4, and the bonding strength between the placement portion 2 and the support portion 3 was low.

Further, Sample No. with SiO ₂ exceeding 65 mass%. 16, Sample No. in which Al ₂ O ₃ is less than 10% by mass. 15, Sample No. with B ₂ O ₃ exceeding 20 mass%. 18, Sample No. with CaO exceeding 5 mass%. 19, Sample No. with MgO exceeding 5 mass%. Sample No. 21 containing 21 mass% and TiO ₂ exceeding 5 mass%. In No. 22, foreign matter due to devitrification was observed, and the bonding strength was low due to the influence of this foreign matter.

In addition, Sample No. in which Al ₂ O ₃ exceeds 40% by mass. _5, Sample B 2 _{O 3} is less than 10 wt% No. 3, Sample No. with BaO exceeding 6 mass%. No. 24 and SrO exceeding 5% by mass Although No. 26 was bonded, the bonding strength was low because the meltability of the glass was poor.

  On the other hand, sample no. 4, 6, 8 to 14, 17, 20, 23, 25 have a good melting property of the glass, and the difference between the thermal expansion coefficient of the binder phase 4 and the thermal expansion coefficients of the mounting part 2 and the support part 3 is shown. While being able to make small, a foreign material does not devitrify, and it can be set as the vacuum chuck with high joint strength between the mounting part 2 and the support part 3. FIG.

(Example 2)
First, α-type silicon carbide powder, silicon powder, and a phenol resin as a molding aid were uniformly mixed to prepare a blended raw material. This blended raw material was put into a tumbling granulator to form granules, and a molded body was obtained by dry pressure molding. Next, this molded body was degreased at 500 ° C. in a nitrogen atmosphere and then heat-treated at 1430 ° C. in the same nitrogen atmosphere to obtain a porous body having a porosity of 30% and an average pore diameter of 50 μm, as shown in FIG. The mounting part 2 was produced.

  The porosity of the mounting portion 2 and the average diameter of the pores 2a were measured by the same method as in Example 1.

Next, the support part 3 which is a substantially disk-shaped dense frame having silicon carbide as a main component and having a circular recess 3a in the center is prepared, and each component of the glass constituting the bonded layer 4 after bonding is prepared. The paste-like glass adjusted so as to become Table 1 was apply | coated to the recessed part 3a. After applying the glass, the mounting portion 2 is placed in the concave portion 3a, pressed in the thickness direction with a dedicated pressurizing device, and then heat treated at 970 ° C. to obtain a vacuum chuck having a bonding layer thickness of 110 to 120 μm. It was.

  And the ratio of each glass component which comprises the coupling layer 4 was measured by the method similar to Example 1. FIG.

  The ratio of the length of the gap 4a of the bonding layer 4 to be bonded to the support 3 = (the length of the gap 4a / (the length of the gap 4a + the length of the joint 4b) × 100) is a scanning type. Using an electron microscope, an image obtained at a magnification of 130 times was obtained in a range where the sum of the length of the gap 4a and the length of the joint 4b was 0.3 mm.

The measurement results are shown in Table 2.

  As can be seen from Table 2, the sample No. 4 in which the ratio of the length of the gap 4a is 45% or less. Nos. 27 and 28 are sample Nos. Whose ratio exceeds 45%. 29 has a higher bonding strength and is suitable.

(Example 3)
First, α-type silicon carbide powder, silicon powder, and a phenol resin as a molding aid were uniformly mixed to prepare a blended raw material. This blended raw material was put into a tumbling granulator to form granules, and a molded body was obtained by dry pressure molding. Next, this molded body was degreased at 500 ° C. in a nitrogen atmosphere and then heat-treated at 1420 ° C. in the same nitrogen atmosphere to obtain a porous body having a porosity of 31% and an average pore diameter of 55 μm, as shown in FIG. The mounting part 2 was produced.

  The porosity of the mounting portion 2 and the average diameter of the pores 2a were measured by the same method as in Example 1.

  Next, the support part 3 which is a substantially disk-shaped dense frame having silicon carbide as a main component and having a circular recess 3a in the center is prepared, and each component of the glass constituting the bonded layer 4 after bonding is prepared. The paste-like glass adjusted so as to become Table 3 was apply | coated to the recessed part 3a. After applying the glass, the mounting portion 2 is placed in the concave portion 3a, pressed in the thickness direction with a dedicated pressurizing device, and then heat treated at 980 ° C. to obtain a vacuum chuck having a bonding layer thickness of 110 to 120 μm. It was.

  And the ratio of each glass component which comprises the coupling layer 4 was measured by the method similar to Example 1. FIG.

  Regarding the bonding strength between the mounting part 2 and the support part 3, after cutting out a 10 mm × 10 mm × 30 mm test piece sandwiching the bonding layer 4 in the center in the longitudinal direction and fixing the porous body, the dense body with a torque wrench. The strength when the test piece was broken was read, and this value was defined as the bonding strength.

At the same time, a pressure resistance test is performed in which water is sprayed onto the bottom surface of the support portion 3 of the vacuum chuck 1 at a pressure of 0.4 MPa and a flow rate of 0.003 m ³ / min. It was confirmed whether or not the support part 3 was detached. Table 3 shows “X” for a sample in which the mounting portion 2 is displaced from the support portion 3, and “◯” for a sample in which the placement portion 2 is not displaced from the support portion 3.

  As can be seen from Table 3, a sample No. having a bonding strength between the mounting portion 2 and the support portion 3 of less than 40 kg · cm. No. 32 is a sample No. 32 with a bonding strength of 40 kg · cm, although the mounting portion 2 was displaced from the support portion 3 in the pressure resistance test. Nos. 30 and 31 can be said to be highly reliable because the mounting part 2 does not deviate from the support part 3 in the pressure resistance test.

Example 4
First, α-type silicon carbide powder, silicon powder, and a phenol resin as a molding aid were uniformly mixed to prepare a blended raw material. This blended raw material was put into a tumbling granulator to form granules, and a molded body was obtained by dry pressure molding. Next, this molded body was degreased at 500 ° C. in a nitrogen atmosphere and then heat-treated at 1430 ° C. in the same nitrogen atmosphere to obtain a porous body having a porosity of 33% and an average pore diameter of 52 μm, as shown in FIG. The mounting part 2 was produced.

  The porosity of the mounting portion 2 and the average diameter of the pores 2a were measured by the same method as in Example 1.

  Next, the support part 3 which is a substantially disk-shaped dense frame having silicon carbide as a main component and having a circular recess 3a in the center is prepared, and each component of the glass constituting the bonded layer 4 after bonding is prepared. The paste-like glass adjusted so as to become Table 3 was apply | coated to the recessed part 3a. After applying the glass, the mounting portion 2 was placed in the concave portion 3a, pressed from the thickness direction with a dedicated pressurizing device, and then heat treated at 980 ° C. to obtain a vacuum chuck.

  The thickness of the bonding layer 4 was measured from an image obtained at a magnification of 130 times using a scanning electron microscope after the heat conduction test described later, and the obtained values are shown in Table 4.

  The obtained vacuum chuck 1 was subjected to a heat conduction test as shown in FIG. Specifically, after placing the vacuum chuck 1 with the mounting portion 2 on the hot plate 6 with the soaking plate 5 made of silicon carbide interposed therebetween, the soaking plate 5 is brought to 60 ° C. with the hot plate 6. Until the temperature of the center of the back surface of the support portion 3 reaches 60 ° C., and the heat is sequentially transmitted through the placement portion 2, the bonding layer 4, and the support portion 3. It can be said that the shorter the time, the better the heat dissipation characteristics as a vacuum chuck.

The temperature at the center of the back surface 3e of the support part 3 is measured by the thermography 7, and Table 4 shows the time required to reach 60 ° C.

  As can be seen from Table 4, the sample nos. No. 33 takes 70 seconds until the temperature at the center of the back surface of the support part 3 reaches 60 ° C., whereas the thickness of the bonding layer is 100 μm or less. It can be said that 34 and 35 are vacuum chucks having good heat dissipation characteristics for 50 seconds or less until the temperature at the center of the back surface of the support portion 3 reaches 60 ° C.

It is a perspective view which shows the vacuum chuck of this invention. It is the sectional view seen from the direction perpendicular to the thickness direction of a vacuum chuck, which shows typically the gap of a bonding layer joined to a support part. It is sectional drawing which shows having evaluated the thermal radiation characteristic of a vacuum chuck by the heat conduction test.

Explanation of symbols

1: vacuum chuck 2: mounting portion 2a: pore 2b: suction surface 3: support portion 3a: concave portion 3b: top surface 3c: suction passage 3d: flange portion 4: bonding layer 4a: gap portion 4b: bonding portion 5: uniform Hot plate 6: Hot plate 7: Thermography

Claims (6)

  A placing portion having an adsorption surface made of a porous body containing at least silicon carbide as a main component and a supporting portion made of a dense body containing silicon carbide as a main component that surrounds and supports the placing portion. In the vacuum chuck bonded with the bonding layer, the bonding layer is 30 to 65% by mass of Si, 10 to 40% by mass of Al, 10 to 20% by mass of B, and 4 to 5% by mass of Ca in terms of oxides. A vacuum chuck comprising 1 to 5% by mass of Mg, 6% by mass or less (excluding 0% by mass) of Ba, and 5% by mass or less (excluding 0% by mass) of Sr. 3. The vacuum chuck according to claim 2 , wherein the total ratio of heavy metal and alkali metal in the bonding layer is 300 ppm by mass or less (excluding 0 ppm by mass). When the vacuum chuck is viewed in cross section, the proportion of the total length of the gap between the support portion and the bonding layer is 45% or less with respect to the total length of the interface between the support portion and the bonding layer. The vacuum chuck according to claim 1 or 2 , wherein: The vacuum chuck according to any one of claims 1 to 3 , wherein the bonding strength between the mounting portion and the support portion is 40 kg · cm or more. Vacuum chuck according to any one of claims 1 to 4 the thickness of the bonding layer is characterized by a 5 to 100 [mu] m. Vacuum suction device, characterized in that the vacuum chuck according used as an adsorption member to one of claims 1 to 5.

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