JP4868885B2 - Method for producing silicon-silicon carbide composite member - Google Patents

Description

  The present invention relates to a silicon-silicon carbide composite member, a manufacturing method thereof, a semiconductor wafer adsorption member and a vacuum adsorption apparatus using the same.

  Conventionally, in order to grind the back surface of the device formation surface of a semiconductor wafer, an adsorption member is provided, and an adsorption member that fixes the semiconductor wafer by vacuum suction on the adsorption surface; a diamond wheel that grinds the semiconductor wafer; Is used. A semiconductor wafer fixed to an adsorbing member 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 has become 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 this 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 in which the back surface of the device forming surface of a semiconductor wafer is polished with a polishing cloth to which abrasive grains are attached has been proposed. Initially, the adsorption member made of an alumina sintered body used in the wafer grinding apparatus was diverted to the adsorption member of the dry polishing wafer polishing apparatus, but the thermal conductivity of the alumina sintered body is low. Therefore, heat cannot be sufficiently released from the semiconductor wafer during grinding with the diamond wheel, and the resin film used to protect the device forming surface melts, resulting in a problem that the device forming surface is damaged. It was.

  In order to solve this problem, attention is paid to the high thermal conductivity of silicon carbide, and ceramic members containing silicon carbide proposed in the following Patent Documents 1 to 4 are considered as objects for studying the adsorbing member.

  Patent Document 1 proposes a porous silicon carbide sintered body having an average crystal grain size of 0.3 to 100 μm and an open porosity of 10 to 60% by volume.

  Patent Document 2 proposes a porous silicon carbide sintered body having an average crystal grain size of 5 to 100 μm, a pore size of 1 to 30 μm, and a porosity of 20 to 60%.

  Patent Document 3 proposes a porous silicon carbide sintered body having an average particle size of silicon carbide crystals of 20 to 100 μm, a porosity of 40% or less, and a thermal conductivity of 80 W / (m · k) or more. Yes.

In Patent Document 4, a silicon-silicon carbide composite member obtained by impregnating silicon carbide with silicon carbide having an average crystal grain size of 20 to 100 μm, a porosity of 10 to 50%, and a thermal conductivity of 160 W / (m · k) or more is disclosed. Proposed.
JP-A-62-100477 JP 2000-16872 A JP 2001-158664 A JP 2002-11653 A

  However, the porous silicon carbide sintered body proposed in Patent Documents 1 to 3 and the silicon-silicon carbide composite member proposed in Patent Document 4 are both composed of small silicon carbide crystal grains having an average grain size of 100 μm or less. As a result, through holes with high linearity cannot be formed, resulting in high pressure loss, and when used as a suction member for a vacuum suction device, the semiconductor wafer cannot be fixed with high accuracy. was there.

  In addition, the porous silicon carbide sintered body proposed in Patent Document 1 is intended for parts for dry etching apparatuses, and has good corrosion resistance against corrosive gas, but has thermal responsiveness and heat dissipation. Therefore, it could only be used for limited applications such as parts for dry etching equipment.

  The porous silicon carbide sintered body proposed in Patent Document 2 has a small pore diameter of 1 to 30 μm, and exhibits good dust collection characteristics when applied to a honeycomb filter that collects and collects fine particles. However, the thermal response and heat dissipation were not considered.

  Moreover, the silicon-silicon carbide composite member proposed in Patent Document 4 was previously mixed with α-type silicon carbide powder having an average particle size of 50 to 100 μm and α-type silicon carbide powder having an average particle size of 0.1 to 1.0 μm. Thereafter, granulation, molding, and firing are performed to obtain a porous silicon carbide sintered body, which is then impregnated with metal silicon to form a dense body, and the manufacturing conditions are set for the dense body. However, it is difficult to set the manufacturing conditions for the porous body, and it is particularly difficult to ensure the strength as the adsorbing member.

  Particularly, conventionally, when the gap and the bubbles of the silicon phase are defined as non-connected portions and a cross section of a specific range of the silicon-silicon carbide composite member is viewed in plan, the area ratio of the non-connected portions = (area of non-connected portions) / ( There is a problem that the area ratio of the non-connected portion is likely to increase abruptly when the area of the silicon phase + the area of the non-connected portion) × 100 (%) becomes 4%.

The present invention, proper ventilation, while having both strength, low pressure loss, thermal response, the heat dissipation of the good silicon - and to provide a method for producing a silicon carbide composite member.

In the method for producing a silicon-silicon carbide composite member according to the present invention, 15 to 30 parts by weight of silicon powder having an average particle diameter of 1 to 90 μm is prepared with respect to 100 parts by weight of α-type silicon carbide powder having an average particle diameter of 105 to 350 μm. Mixing and granulating to obtain granules, molding the granules into a predetermined shape to obtain a molded body, and heat-treating the molded body at 1400 to 1450 ° C. in a non-oxidizing atmosphere. It is characterized by that.

According to the method for producing a silicon-silicon carbide composite member according to the present invention, 15 to 30 parts by weight of 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. , Uniformly mixing and granulating to obtain granules, forming the granules into a predetermined shape to obtain a molded body, and heat-treating the molded body at 1400 to 1450 ° C. in a non-oxidizing atmosphere by comprising the step, a low pressure loss property, thermal response, silicon and combines the heat radiation - it can be produced inexpensively and efficiently carbide composite member.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic view showing the inside of the silicon-silicon carbide composite member of the present invention.

  The silicon-silicon carbide composite member of the present invention has a three-dimensional network structure in which a plurality of silicon carbide crystal particles are arranged three-dimensionally and adjacent silicon carbide crystal particles are joined by a silicon phase. In addition, the silicon carbide crystal particles 1 are connected through the silicon phase 3 between the pores 2a and 2b as shown in FIG. And a silicon-silicon carbide composite member in which a plurality of silicon carbide crystal particles are arranged three-dimensionally and a three-dimensional network structure is formed in which adjacent silicon carbide crystal particles are joined by a silicon phase. The area ratio of the non-connected portion in the range of 2200 μm × 1700 μm when the cross section of the silicon-silicon carbide composite member is viewed in plan, with the gap and bubbles of the silicon phase as non-connected portions = (surface of the non-connected portion) ) / (Area of silicon phase + the area of the non-connecting portion) × 100 (%) is characterized in that at most 3.5%.

  Even if the silicon phase 3 between the silicon carbide crystal particles 1 has pores or the silicon phase 3 is U-shaped and is bonded to one silicon carbide crystal particle at two points, If the crystal grains 1 and the silicon phase 3 have the same total bonding area, there is almost no difference in thermal conductivity. However, if the silicon phase 3 is branched into a plurality of parts, the silicon phase 3 requires a bonding area correspondingly, and therefore, it is preferable that the silicon phase 3 is bonded by a lump of silicon phase 3 that is not branched as much as possible.

  Both the silicon carbide crystal particles 1 and the silicon phase 3 have good thermal response and heat dissipation, and in the silicon-silicon carbide composite member of the present invention, the silicon phase 3 connects the silicon carbide crystal particles 1. Silicon has good wettability with respect to silicon carbide, and is easily deposited on the silicon carbide crystal particles 1, and the deposited silicon is connected to each other to form a silicon phase 3. In this formation process, it is important that the gap 4a and the bubbles 4b are not generated as much as possible in the silicon phase 3 in the non-connection portion 4 as shown in FIG. This is because such an unconnected portion 4 reduces the thermal response and heat dissipation.

  The presence / absence of the unconnected portion 4 can be observed within a range of 1.8 mm × 2.0 mm using a scanning electron microscope, for example, with a magnification of 50 to 5000 times.

  The area ratio of the non-connecting portion 4 is a ratio defined by the following formula (1), and can be measured and calculated by the following method. The thermal responsiveness and heat dissipation of the silicon-silicon carbide composite member It is preferable to reduce the area ratio of the unconnected portion, and it is important that the upper limit is 3.5%.

Area ratio of unconnected portion = (area of unconnected portion) / (area of silicon phase + area of unconnected portion)
× 100 (%) (1)
That is, a part of the silicon-silicon carbide composite member is embedded in a resin in a vacuum to obtain a cylindrical sample,
After polishing the flat surface of the sample with diamond abrasive grains to obtain a mirror surface, an image obtained by photographing the mirror surface at 5 to 50 times is stored in JPEG format using an industrial microscope (Nikon ECLIPSE LV150). .

  Next, the image file saved in the PEG format is subjected to image processing using software called Adobe Photoshop Elements (registered trademark) and saved in the BMP format. Specifically, the chromatic color on the image is deleted and black and white gradation (black and white) is performed. In this two-gradation, a threshold value for distinguishing between silicon carbide crystal particles 1 and silicon phase 3 is set while comparing with an image taken with an industrial microscope (Nikon ECLIPSE LV150).

  After setting the threshold value, the area of the silicon phase 3 is read in units of pixels from the two-graded image using free software “area from image”.

  The unconnected portion 4 is also read by the same method as described above and calculated by the equation (1).

  When impregnating molten silicon into a silicon carbide molded body, it is possible to selectively fill the cracks existing inside the granules constituting the molded body by capillary action, and the silicon phase cannot sufficiently bond the silicon carbide crystal particles. , Suitable strength, thermal responsiveness and heat dissipation cannot be obtained.

  Moreover, it is preferable that the average particle diameter of the silicon carbide crystal particles constituting the silicon-silicon carbide composite member is 105 to 350 μm.

The average particle size of the silicon carbide crystal particles is set to 105 μm or more.
This is because small pores may be formed or closed pores that do not contribute to vacuum adsorption may be formed, and even when used as an adsorption member, sufficient adsorption force may not be obtained. On the other hand, the reason why the average particle size is set to 350 μm or less is that when it exceeds 350 μm, extremely large pores may be formed, and the strength may be lowered. Since the formation of closed pores that do not contribute to vacuum adsorption can be prevented by setting the average particle size of the silicon carbide crystal particles to 105 to 350 μm, it is possible to obtain a sufficient adsorption force, and extremely large pores are not formed. It can be set as the silicon-silicon carbide composite member in which intensity | strength does not fall.

  The average particle diameter of the silicon carbide crystal particles is measured, for example, by an intercept method using a scanning electron microscope (hereinafter referred to as SEM) having a magnification of 20 to 800 times, or obtained by SEM. The obtained observation image with a magnification of 20 to 800 times can be obtained by numerical analysis. When using the intercept method, specifically, the grain size is measured from the number of crystal grain boundaries on a straight line of a certain length from several SEM photographs so that the number of samples is 10 or more, preferably 20 or more. The average is calculated.

  Furthermore, it is preferable that the porosity of the silicon-silicon carbide composite member is 30 to 40%.

  The reason why the porosity is set to 30% or more is that when the porosity is less than 30%, there is a possibility of increasing pressure loss. On the other hand, the reason why the porosity is set to 40% or less is that if it exceeds 40%, the thermal conductivity and the strength may be lowered.

  By setting the porosity to 30 to 40%, a silicon-silicon carbide composite member that does not cause an increase in pressure loss or decrease in thermal conductivity or strength can be obtained.

  The porosity of the silicon-silicon carbide composite member can be determined by the Archimedes method.

  It is also preferable that the average pore diameter is 40 to 120 μm.

  The reason why the average diameter of the pores is set to 40 μm or more is that, when the pore diameter is less than 40 μm, there is a possibility of causing pressure loss as in the case of the porosity of less than 30%. On the other hand, the reason why the thickness is 120 μm or less is that when the thickness exceeds 120 μm, the strength may decrease as in the case where the porosity exceeds 40%. Also, when used as a suction member for fixing a semiconductor wafer, the suction surface is partially recessed during vacuum suction, and the semiconductor wafer is fixed following the recess, so that the flatness of the polished semiconductor wafer surface is poor. In some cases. By setting the pore diameter to 40 to 120 μm, it is possible to obtain a silicon-silicon carbide composite member that does not cause pressure loss or decrease in strength. In addition, a silicon-silicon carbide composite member having an average pore diameter of 40 to 120 μm is used as an adsorbing member, and a semiconductor wafer having excellent surface flatness can be obtained even if the semiconductor wafer is fixed and polished by vacuum suction.

  The average pore diameter of the silicon-silicon carbide composite member can be determined by a mercury intrusion method according to JIS R 1655-2003.

  Furthermore, since the silicon carbide crystal particles are polyhedron and the ratio of the number of hexahedrons or more is 80% or more, the contact between the silicon carbide crystal particles is increased, so that thermal response and heat dissipation are better. A silicon-silicon carbide composite member can be obtained.

  If it is less than 80%, the contact between crystal grains of silicon carbide may be insufficient, and there is a possibility that the thermal responsiveness and the heat dissipation property are locally lowered.

In particular, the ratio of the number of hexahedrons or more is more preferably 90% or more.

  Further, FIG. 3 shows an enlarged view of the silicon-silicon carbide composite member of the present invention. The width (w) of the joint portion between the silicon carbide crystal particles 1 and the silicon phase 3 shown in this enlarged view is changed to silicon carbide. If the length (L) of the minimum side of the polyhedron forming the crystal grains 1 is 0.2 times or more, the bonding strength between the silicon carbide crystal grains 1 and the silicon phase increases, so that the silicon-silicon carbide composite The strength as a member is also improved. In addition, since the area (S) of the silicon phase 3 is increased, the thermal response and heat dissipation are improved, and in particular, the width (w) is preferably 0.5 times or more of the length (L). .

  If it is less than 0.2 times, the bonding strength between the silicon carbide crystal particles and the silicon phase may be insufficient, and the bonding strength may be locally reduced.

  Furthermore, the ratio of silicon carbide particles having higher mechanical strength than the silicon phase can be increased by sandwiching the silicon phase and setting the distance (d) between the opposed silicon carbide particles to 350 μm or less. The strength as a silicon composite member is also improved.

  If it is larger than 350 μm, the ratio of silicon carbide particles having a melting point higher than that of the silicon phase is low, and the ratio of the silicon phase is relatively high, which causes a problem that it is difficult to use in a high temperature environment.

  The width (w) of the joint, the length (L) of the minimum side, and the distance (d) between the silicon carbide particles can be obtained from an SEM photograph with a magnification of 20 to 800 times, and when more accurate measurement is required. An SEM photograph of a surface that has been subjected to mirror filling with pores filled with cold embedding resin such as polyester resin may be used.

  The three-point bending strength and Young's modulus of the silicon-silicon carbide composite member are preferably 30 MPa or more and 30 GPa or more, respectively.

  When the three-point bending strength is less than 30 MPa or the Young's modulus is less than 30 GPa, when the silicon-silicon carbide composite member is used as an adsorption member for fixing a semiconductor wafer by vacuum suction, depending on the ultimate vacuum, the silicon-silicon carbide composite member This is because the generated micro-vibration cannot be suppressed. By setting the three-point bending strength and Young's modulus of the silicon-silicon carbide composite member to 30 MPa or more and 30 GPa or more, respectively, the degree of freedom in ultimate vacuum can be increased, and the semiconductor wafer Can be stably fixed, and the processing performance is also improved.

  The three-point bending strength is measured according to JIS R 1601-1995, and the Young's modulus is the amount of displacement at the load point or the center of the test piece in the three-point bending test specified in JIS R 1602-1995. Calculate from

  Furthermore, it is preferable to coat silicon carbide crystal particles with silicon. This is because the silicon carbide crystal particles are covered with silicon, so that the risk of silicon carbide shed during use is lost.

Subsequently, the manufacturing method of the silicon-silicon carbide composite member of this invention is demonstrated.
In order to obtain the silicon-silicon carbide composite member of the present invention, first, 15 to 30 parts by weight of silicon powder having an average particle diameter of 1 to 90 μm is prepared with respect to 100 parts by weight of α-type silicon carbide powder having an average particle diameter of 105 to 350 μm. As a molding aid, a thermosetting resin such as a phenol resin, an epoxy resin, a furan resin, a phenoxy resin, a melamine resin, a urea resin, an aniline resin such that the residual carbon ratio after the subsequent degreasing treatment is 30% or more. Then, at least one of 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 silicon-silicon carbide composite member. In order to set the porosity of the silicon-silicon carbide composite member 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. This is because the pressure loss is increased, and when it exceeds 350 μm, the density of the silicon-silicon carbide composite member is decreased, so that the strength is decreased. By setting the average particle size of the α-type silicon carbide powder to 105 to 350 μm, a silicon-silicon carbide composite member having low pressure loss and no strength reduction can be obtained. Further, the silicon powder becomes a silicon layer in a later 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, a silicon-silicon carbide composite member having a homogeneous structure with sufficient mechanical characteristics can be obtained.

  As described above, the width of the bonded portion between the silicon carbide crystal particles and the silicon phase depends on the ratio of the silicon powder, and the width of the bonded portion between the silicon carbide crystal particles and the silicon phase corresponds to the silicon carbide crystal particles. In order to make it 0.2 times or more the minimum side length of the polyhedron to be formed, the ratio may be 20 to 30 parts by weight.

  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 μm, it is preferable to use a rolling granulator.

  The shape of the silicon carbide crystal particles forming the silicon-silicon carbide composite member is governed by the granulation time. If the granulation time is lengthened, the shape becomes closer to an elliptical sphere, and if the granulation time is shortened, it becomes a polyhedron.

  In order that the crystal grains of silicon carbide are polyhedral and the ratio of the number of hexahedrons or more is 80% or more, the granulation time should be 40 minutes or less, and 30 minutes or more in consideration of the crushability of the compact. Is preferred.

  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 member 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.

  The average particle diameter of silicon carbide crystal particles forming the silicon-silicon carbide composite member, the average diameter of the pores, the distance between the silicon carbide particles facing each other across the silicon phase, the three-point bending strength, and the Young's modulus depend on the molding pressure. It depends. If the molding pressure is increased, the silicon carbide crystal particles, the average diameter of the pores, and the distance between the silicon carbide particles are shortened, and if the molding pressure is lowered, the distance is increased. Further, the three-point bending strength and Young's modulus have a positive correlation with the molding pressure. Based on such a relationship, in order to make the average particle diameter of the silicon carbide crystal particles 105 to 350 μm, it may be 160 MPa or less. Further, in order to set the average pore diameter to 40 to 120 μm, the molding pressure may be set to 80 to 140 MPa, and in order to reduce the distance between the silicon carbide particles to 350 μm or less, the molding pressure may be set to 100 MPa or more. Further, in order to make the three-point bending strength 30 MPa or more and the Young's modulus 30 GPa or more, the molding pressure may be 120 MPa or more.

  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 1420 to 1450 ° C. By performing heat treatment in this temperature range, a silicon-silicon carbide composite member 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 silicon-silicon carbide composite member obtained by such a manufacturing method can be machined, such as grinding and polishing, as required, to obtain a desired product.

  In particular, the silicon-silicon carbide composite member is preferably used as an adsorbing member for fixing a semiconductor wafer by producing an adsorbing surface by grinding and polishing and vacuum-suctioning the adsorbing surface.

  The suction surface needs to be flattened as much as possible because the surface state affects the accuracy of the processed semiconductor wafer, and it is desired that the flatness be at least 1 μm or less, preferably 0.3 μm or less. .

  Further, in the vacuum suction device in which the adsorption member is fixed to the support member via the bonding layer, the bonding layer is mainly composed of glass or silicon, and the support member is a sintered body mainly composed of silicon carbide. It is preferable to do.

When the bonding layer is mainly composed of glass, the thermal expansion coefficient is preferably relatively close to that of silicon carbide or silicon. For example, the thermal expansion coefficient is 3.0 to 5.5 × 10 ^−6. / ° C is preferred.

  Moreover, the softening point of the said glass should just be lower than melting | fusing point of silicon carbide or silicon, what is necessary is just to use a softening point of 900-920 degreeC, for example, specifically, borosilicate glass and silicate glass are suitable. is there.

  By fixing the adsorbing member using the silicon-silicon carbide composite member of the present invention and the supporting member made of a sintered body containing silicon carbide as a main component through a bonding layer containing glass or silicon as a main component. The occurrence of cracks and peeling at the joint interface can be prevented. Therefore, even if it receives a heat cycle, it cannot be destroyed easily and it can be set as the vacuum suction apparatus excellent in long-term reliability. In particular, when the bonding layer contains silicon as a main component, the thermal conductivity is high and good as compared with the case where the bonding layer is formed with a general resin adhesive.

  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 the temperature was raised and heat treatment was performed in the same nitrogen atmosphere.

  The α-type silicon carbide powder used in the above method, the average particle diameter of the silicon powder, the ratio of the silicon powder and the phenol resin to the α-type silicon carbide powder, the granulation time, the molding pressure and heat treatment in dry press molding The temperature is as shown in Table 1.

  About the obtained sample, silicon | silicone which connects between pores by selecting an optimal magnification from 20-800 times or 300-5000 times according to each evaluation item of a sample using a scanning electron microscope. Presence / absence of phase, presence / absence of unconnected portion, ratio of number of hexahedral or more silicon carbide crystal particles, width of silicon carbide crystal particle / silicon phase junction, sandwiching silicon phase, and facing silicon carbide particles The distance and the coating state of silicon carbide crystal particles with silicon were evaluated. In Table 1, the case where the silicon phase communicating between the pores was observed was indicated as ◯, and the case where the silicon phase was not observed was indicated as ×. Further, the area ratio of the unconnected portion was calculated by the following method and mathematical formula, and the values are shown in Table 1.

Area ratio of unconnected portion = (area of unconnected portion) / (area of silicon phase + area of unconnected portion)
× 100 (%) (1)
That is, a part of the silicon-silicon carbide composite member is embedded in a resin in a vacuum to obtain a cylindrical sample,
After polishing the flat surface of the sample with diamond abrasive grains to obtain a mirror surface, an image obtained by photographing the mirror surface at a magnification of 5 using an industrial microscope (Nikon ECLIPSE LV150) was stored in JPEG format. Next, the image file saved in the PEG format was subjected to image processing using software called Adobe Photoshop Elements (registered trademark) and saved in the BMP format. Specifically, the chromatic color on the image was deleted, and black and white gradation (black and white) was performed. In this two-gradation, a threshold value for distinguishing the silicon carbide crystal particles 1 and the silicon phase 3 was set while comparing with an image taken with an industrial microscope (Nikon ECLIPSE LV150). After setting the threshold value, the area of the silicon phase 3 was read in pixel units from the two-graded image using free software “area from image”.

  The unconnected portion 4 was also read in the same manner as described above and calculated by the equation (1).

The case where silicon completely covered silicon carbide crystal particles was indicated by ◯, and the case where silicon was not partially covered was indicated by Δ.

  Lasers defined in Archimedes method, JIS R 1655-2003, JIS R 1601-1995, and JIS R 1602-1995 for the porosity, average pore diameter, three-point bending strength, Young's modulus, and thermal conductivity of the above samples. Measured according to the flash method.

In addition, the pressure loss is formed in a cylindrical body having a diameter of 60 mm and a height of 10 mm. Air is introduced from one end face of this cylindrical body, and the side surface is covered in advance so that air is discharged only from the opposite end face. The pressure difference generated before and after the introduction of air at a flow rate of 9 L / min was detected as a pressure loss by a pressure gauge.

  As shown in Table 1, Sample No. No. 1 has an average particle diameter of α-type silicon carbide powder of less than 105 μm, so the average diameter of the pores was as small as 48 μm, and as a result, the pressure loss was as high as 1.05 kPa. Sample No. No. 32 had a three-point bending strength as low as 12 MPa because the average particle size of the α-type silicon carbide powder was larger than 350 μm.

  Sample No. No. 3 has an average particle size of silicon powder of less than 1 μm, so the area ratio of the unconnected portion is as large as 3.7%, and the three-point bending strength and thermal conductivity are 13 MPa and 58 W / (m · k), respectively. It was low. Sample No. In No. 30, since the average particle size of the silicon powder was larger than 90 μm, the average diameter of the pores was as large as 140 μm and the three-point bending strength was as low as 13 MPa.

Sample No. No. 5 has a silicon powder ratio of less than 15 parts by weight with respect to 100 parts by weight of α-type silicon carbide powder, so the area ratio of the unconnected part is as large as 3.7%, and the three-point bending strength and thermal conductivity are both high. They were as low as 13 MPa and 60 W / (m · k), respectively. Sample No. 28, with respect to α-type silicon carbide powder 100 parts by weight, since the ratio of the silicon powder is greater than 3 0 parts by weight, the segregation of silicon was observed, three-point bending strength was as low as 14 MPa.

  Sample No. In No. 7, since the heat treatment temperature was less than 1400 ° C., the silicon powder could not be sufficiently melted, so that a silicon-silicon carbide composite member could not be formed. Sample No. In No. 26, since the heat treatment temperature exceeded 1450 ° C., silicon evaporated and the strength was lowered, and the three-point bending strength was as low as 10 MPa.

  On the other hand, sample no. 2,4,6,8-25,27,29,31,33 are high in three-point bending strength of 22 MPa or more, Young's modulus of 22 GPa or more, thermal conductivity of 70 W / (m · k) or more, and pressure loss. Is as low as 0.85 kPa or less, and is found to be favorable.

  In particular, sample Nos. 2, 4, 6, 8-12, 14-20, 22-25, 27, 29, 31, 33 with a porosity of 30-40% have a three-point bending strength of 23 MPa or more and a Young's modulus of 24 GPa. As described above, it can be seen that both the thermal conductivity is 70 W / (m · k) or higher and the pressure loss is 0.85 kPa or less, which is preferable.

  Furthermore, the sample No. having a porosity of 30 to 40% and an average pore diameter of 40 to 120 μm. 2, 4, 6, 8, 9, 12, 14-19, 22-25, 27, 29, 33 have a three-point bending strength of 25 MPa or more, Young's modulus of 26 GPa or more, and thermal conductivity of 71 W / (m · k) or more. Both are high and the pressure loss is as low as 0.43 kPa or less.

  By the way, sample no. Nos. 9, 22 and 23 are samples in which the change in the ratio of the number of crystal grains of hexahedrons among the silicon carbide crystal grains forming the polyhedron is examined by changing only the granulation time, and the granulation time can be increased. For example, the ratio decreases, the contact between the silicon carbide crystal particles decreases, and the thermal conductivity also decreases.

  The porosity is 30 to 40%, the average pore diameter is 40 to 120 μm, and the width of the junction between the silicon carbide crystal particles and the silicon phase is the minimum side of the polyhedron forming the silicon carbide crystal particles Sample no. 2, 4, 8, 9, 12, 14-19, 22-25, 27, 29, 33 are three-point bending strength of 25 MPa or more, Young's modulus of 26 GPa or more, thermal conductivity of 73 W / (m · k) or more. In addition, the pressure loss is low and good at 0.85 kPa or less.

  In this example, a sample having a silicon phase sandwiched between the silicon carbide particles facing each other and having a distance of 350 μm or less has a width of the junction between the silicon carbide crystal particles and the silicon phase. Sample No. 0.2 or more times the minimum side length of the polyhedron to be formed. 2, 4, 8, 9, 12, 14-19, 22-25, 27, 29, 33.

It is a schematic diagram which shows the silicon-silicon carbide composite member inside of this invention. It is a schematic diagram which shows a non-connecting part. It is an enlarged view inside the silicon-silicon carbide composite member of this invention, and is a schematic diagram which shows the distance (d) between the width | variety (w) of a junction part of the crystal grain of a silicon carbide and a silicon phase, and a silicon carbide particle.

Explanation of symbols

1: Silicon carbide crystal particles 2: Pore 3: Silicon phase 4: Unconnected portion

Claims (1)

A step of preparing 15 to 30 parts by weight of silicon powder having an average particle size of 1 to 90 μm, mixing and granulating to 100 parts by weight of α-type silicon carbide powder having an average particle size of 105 to 350 μm,
Forming the granules into a predetermined shape to obtain a molded body;
Heat treating the molded body at 1400 to 1450 ° C. in a non-oxidizing atmosphere;
A method for producing a silicon-silicon carbide composite member, comprising:

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