JP5872956B2 - Silicon carbide sintered body, electrostatic adsorption member comprising this silicon carbide sintered body, and member for semiconductor manufacturing apparatus - Google Patents

Description

  The present invention relates to a silicon carbide sintered body, an electrostatic adsorption member made of the silicon carbide sintered body, and a member for a semiconductor manufacturing apparatus.

In the semiconductor manufacturing process, an electrostatic chucking member made of ceramics is used for transporting and holding a semiconductor wafer. Further, as the ceramic used for the electrostatic attraction member, a silicon carbide sintered body having high thermal conductivity is used in order to efficiently dissipate heat applied when forming a circuit pattern on a semiconductor wafer. As this silicon carbide based sintered body, one having a high volume resistivity is used in order to prevent a current applied to the electrostatic attraction member from being transmitted to the semiconductor wafer. As a silicon carbide-based sintered body having a high volume resistivity, Patent Document 1 discloses that the nitrogen content is 0.4 wt% or more and 0.5 wt% or less, a part of nitrogen is solid-solved in the silicon carbide crystal, and the remainder is There has been proposed a silicon carbide based sintered body that exists as a boron nitride crystal at a silicon carbide crystal grain boundary and has a volume resistivity of 0.1 G (10 ⁸ ) Ωcm or more.

JP 2006-240960 A

However, the silicon carbide sintered body proposed in Patent Document 1 has a varistor characteristic in which the volume resistivity rapidly decreases when a voltage with a certain high electric field strength (V / mm) is applied. It was a thing. Therefore, for example, when the electrostatic adsorption member made of the silicon carbide sintered body is applied with a voltage with an electric field strength of 600 V / mm and adsorbs the semiconductor wafer, the volume resistivity of the silicon carbide sintered body decreases. In this state, there is a possibility that current flows through the semiconductor wafer and destroys the element formed on the semiconductor wafer.

  The present invention has been devised to solve the above problems, and a silicon carbide sintered body capable of maintaining a high volume resistivity even when an electric field having a high electric field strength is applied, and the silicon carbide-based sintered body. An object of the present invention is to provide an electrostatic attraction member and a member for a semiconductor manufacturing apparatus that are formed of a ligated body.

Silicon carbide sintered body of the present invention, the crystal of silicon carbide as a main phase, and have a first subphase containing carbon and nitrogen, 3C type of crystalline polymorph of the silicon carbide crystal And the sum of the ratios of the 4H types is 20% or less, and the relative density is 96.5% or more .

  Moreover, the electrostatic attraction member of the present invention is characterized by comprising a silicon carbide sintered body having the above-described configuration.

  A member for a semiconductor manufacturing apparatus according to the present invention is characterized by comprising a silicon carbide sintered body having the above-described configuration.

According to the silicon carbide based sintered body of the present invention, the silicon carbide crystal is the main phase and includes the first subphase containing carbon and nitrogen, and the 3C type of crystal polymorph of the silicon carbide crystal And the sum of the ratios of the 4H types is 20% or less, and the relative density is 96.5% or more. Therefore, by suppressing the conductivity of carbon by nitrogen, a voltage with high electric field strength is applied. Also, a high volume resistivity can be maintained.

  Moreover, according to the electrostatic attraction member of the present invention, since it consists of the silicon carbide-based sintered body of the present invention, a high volume resistivity can be maintained even when a voltage with high electric field strength is applied. The reliability can be high.

  In addition, according to the member for a semiconductor manufacturing apparatus of the present invention, since the silicon carbide sintered body of the present invention is used, a high volume resistivity can be maintained even when a voltage with high electric field strength is applied. , Can be reliable.

It is a schematic diagram which shows an example of a structure of the crystal | crystallization of the silicon carbide sintered body of this embodiment. It is a schematic sectional drawing which shows an example of the electrostatic adsorption apparatus provided with the electrostatic adsorption member of this embodiment. It is a schematic sectional drawing which shows an example of the plasma etching apparatus provided with the member for semiconductor manufacturing apparatuses of this embodiment. An example of the circuit board provided with the silicon carbide sintered body of this embodiment as a heat dissipation board is shown, (a) is a top view, (b) is a sectional view in an AA 'line of (a). is there.

  Hereinafter, the silicon carbide based sintered body of the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the crystal structure of the silicon carbide based sintered body of the present embodiment.

  As shown in FIG. 1, the silicon carbide based sintered body 1 of the present embodiment has a main phase 2, which is silicon carbide, and a first subphase 3 containing carbon and nitrogen. Here, the first subphase 3 is, for example, a phase formed by aggregating carbon and nitrogen alone, or a phase formed of graphite-like carbon nitride or amorphous carbon nitride which is a compound of carbon and nitrogen. In addition, a compound composed of carbon and nitrogen is not recognized as a phase in which carbon and nitrogen are singly assembled. For example, the components of the phase are determined using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer. When analyzed, refers to the phase in which carbon and nitrogen have been identified.

In the silicon carbide based sintered body of the present embodiment, the first subphase 3 is configured as described above, so that the conductivity of carbon is considered to be suppressed by nitrogen, and a voltage with high electric field strength is applied. Also, a high volume resistivity can be maintained. The main phase 2 preferably has a low content of elements other than carbon and silicon, such as nitrogen and boron, and 100% by mass of silicon carbide constituting the main phase 2
On the other hand, the nitrogen and boron contents are each preferably 0.1% by mass or less.
In main phase 2, the content of elements other than carbon and silicon is limited, and by containing elements other than carbon and silicon, an increase in the number of lattice defects of crystals constituting main phase 2 is suppressed. be able to. That is, since a decrease in volume resistivity due to current flowing through lattice defects can be suppressed, a silicon carbide sintered body having a larger volume resistivity can be obtained.

  The first subphase 3 is preferably a phase having a circular cross section, and the residual stress generated in the main phase 2 can be reduced, so that the mechanical characteristics are not easily lowered.

Further, the carbon and nitrogen contents in the first subphase 3 are, for example, 30% to 80% by atom of carbon and 20% by atom of nitrogen with respect to the elements constituting the first subphase 3. When the content is 70 atomic% or less, a high volume resistivity can be maintained even when a voltage with high electric field strength is applied, which is preferable. In addition to carbon and nitrogen, at least one of boron, silicon, and argon may be included as long as the content is less than the respective contents of these elements. For example, boron, silicon, and argon can be contained in a total amount of 25 atomic% or less with respect to the elements constituting the first subphase 3.

  Note that the content (atomic%) of each element in the first subphase 3 can be obtained by a thin film approximation method using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer. The measurement time and the measurement energy width may be 50 seconds and 0.14 to 20.5 keV, for example.

In addition, silicon carbide sintered body 1 of the present embodiment has a silicon carbide sintered body 1 having a nitrogen content of 0.3 mass% to 1 mass% with respect to 100 mass% of silicon carbide sintered body. There is a tendency that the volume resistivity can be maintained high, and further, mechanical properties such as static elastic modulus and mechanical strength can be maintained high.

  Moreover, it is preferable that the silicon carbide based sintered body 1 of the present embodiment further has boron nitride as the second subphase 4.

  When boron nitride is used as the second subphase 4, even when a voltage with high electric field strength is applied, the volume resistivity can be maintained higher due to the presence of the second subphase 4 that is less likely to pass electricity than silicon carbide. .

Further, when the silicon carbide based sintered body 1 of this embodiment has boron nitride as the second subphase 4, the nitrogen content with respect to 100% by mass of the silicon carbide based sintered body is the nitrogen constituting the boron nitride. If the content is 0.55% by mass or more and 1.2% by mass or less, the volume resistivity of the silicon carbide-based sintered body 1 tends to be maintained at a higher level, and the static elastic modulus, mechanical strength, etc. There is a tendency that the mechanical characteristics can be maintained higher, which is preferable.

  Here, a method for confirming the presence of the first subphase 3 and the second subphase 4 included in the silicon carbide based sintered body 1 will be described.

  First, an observation sample is prepared by processing the silicon carbide sintered body 1 into a thin film by an ion milling method using argon (Ar) ions. Note that the thinned sample for observation is cut to a thickness of about 1 mm, for example, and then punched to a size that can be attached to the holder of the apparatus used for measurement, centering on the portion to be observed.

  Then, using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer, for example, the observation sample is magnified, the acceleration voltage and the observation range are 12500 times, 200 kV, 14.5 μm × 14.5 μm, and the components of each phase are identified. Thus, the presence of the first subphase 3 and the second subphase 4 can be confirmed.

  Further, the content of each phase component contained in the silicon carbide based sintered body can be determined as follows.

  First, the contents of silicon and boron contained in the silicon carbide based sintered body are determined by ICP (Inductively Coupled Plasma) emission spectroscopic analysis or fluorescent X-ray analysis. As a specific method for obtaining the content by ICP emission spectroscopic analysis, boric acid and sodium carbonate are added and melted to a sample obtained by pulverizing a part of a silicon carbide sintered body in a superhard mortar as a pretreatment. Then, after standing to cool, it is dissolved in a hydrochloric acid solution, and the solution is transferred to a flask, diluted with water to a standard line to obtain a constant volume, and measured with an ICP emission spectrometer together with a calibration curve solution. The amount can be determined. When obtaining the boron content, as a pretreatment, a part of the silicon carbide sintered body 1 is melted by adding only sodium carbonate to a sample pulverized in a cemented mortar, and the others are the above-described silicon. What is necessary is just like the case.

  Further, the carbon and nitrogen contents contained in the silicon carbide sintered body 1 may be measured according to the chemical analysis method for fine silicon carbide powder defined in JIS R 1616-2007, and more specifically. May use the infrared absorption method for carbon and the thermal conductivity method for nitrogen.

  Next, the composition formula of the main phase constituting the silicon carbide based sintered body 1 is identified by an X-ray diffraction method using CuKα rays, and components other than silicon carbide, for example, boron or nitrogen are added to the main phase 2. In the case of solid solution, the spectrum obtained by the X-ray diffraction method is analyzed by the Rietveld method to determine each solid solution amount (each content) of boron and nitrogen in the main phase 2.

  For example, the silicon carbide-based sintered body 1 is silicon carbide (main phase 2), a phase formed of carbon and nitrogen alone (first subphase 3), and boron nitride (second subphase 4). From the silicon content, the amount of carbon in the main phase 2 is calculated, and the amount of carbon in the main phase 2 is calculated from the amount of carbon in the silicon carbide based sintered body 1. By subtracting, the amount of carbon in the first subphase 3 can be calculated. Further, the content of boron contained in the silicon carbide based sintered body 1 is regarded as boron in the second subphase 4, and the amount of nitrogen in the second subphase 4 is calculated from the amount of boron. The amount of nitrogen in the first subphase 3 can be calculated by subtracting the amount of nitrogen in the subphase 4 from the amount of nitrogen in the silicon carbide sintered body 1. That is, the content of the first subphase 3 can be calculated. When the main phase 2 contains boron, the amount of boron in the second subphase 4 depends on the amount of boron contained in the silicon carbide sintered body 1 from the content of boron in the main phase 2. What is necessary is just to consider it as the quantity which deducted content.

  Moreover, in the silicon carbide based sintered body 1 of the present embodiment, it is preferable that the sum of the proportions of the 3C type and 4H type in the silicon carbide crystal polymorph is 20% or less.

  It is known that silicon carbide includes 2H type, 3C type, 4H type, 6H type, 15R type, 33R type, and the like as crystal polymorphs classified by the difference in crystal structure and lamination period. In general, silicon carbide sintered bodies are classified into 3C type, also referred to as β type, and 4H type, 6H type, and 15R type, also referred to as α type, as crystal polymorphs. Since the 3C type and 4H type are crystal polymorphs containing many lattice defects, the total of the proportions of the 3C type and 4H type in the crystal polymorphs of silicon carbide is set to 20% or less so that the current flows through the lattice defects Since the decrease of the volume resistivity due to the flowing of can be suppressed, the silicon carbide sintered body 1 having a larger volume resistivity can be obtained.

  In addition, each crystal polymorph can be quantified by obtaining the spectrum obtained by the X-ray diffraction method by the Rietveld method, and the ratio of 3C type and 4H type can be obtained based on the quantified value of each crystal polymorph. That's fine.

Further, in the silicon carbide based sintered body 1 of the present embodiment, it is preferable that the boron content is 0.5 mass% or less.

  By limiting the boron content, it is possible to suppress an increase in lattice defects of the silicon carbide crystal due to the boron content, so that the volume resistivity of the silicon carbide based sintered body 1 can be kept high. it can.

Moreover, the silicon carbide based sintered body 1 of the present embodiment has a chromium, manganese, iron, cobalt, nickel, copper, vanadium, zirconium and tungsten content of 200 mass pp each.
m or less is preferred.

By adopting such a configuration, the amount of the metal component that promotes the flow of electricity is limited, and the electricity can be made difficult to flow. Therefore, the silicon nitride sintered body 1 that can maintain a larger volume resistivity is obtained. be able to. What is necessary is just to obtain | require each content of these metal components by an ICP emission spectroscopy analysis method or a fluorescent X ray analysis method.

  In addition, the silicon carbide based sintered body 1 of the present embodiment preferably has a relative density of 96.5% or more.

  By setting it as such a structure, the mechanical strength of the silicon carbide based sintered compact 1 can be maintained high. In addition, the relative density of the silicon carbide based sintered body 1 is obtained as an apparent density of the silicon carbide based sintered body 1 in accordance with JIS R 1634-1998, and this apparent density is obtained from the silicon carbide based sintered body 1. It may be obtained by dividing by the theoretical density.

Moreover, the silicon carbide based sintered body 1 of this embodiment forms electrodes made of silver on both principal surfaces, and has a volume resistivity of 10 when a voltage with an electric field strength of 600 V / mm is applied between the electrodes. It is preferably ⁷ Ω · m or more and 10 ¹⁰ Ω · m or less.

When the volume resistivity of the silicon carbide based sintered body 1 is in the above range, for example, when the silicon carbide based sintered body 1 is used as an electrostatic attraction member, a voltage having a high electric field strength of 600 V / mm is applied. However, since high volume resistivity can be maintained, it can be made highly reliable. Further, when the volume resistivity is in the above range, Johnson-Rahbek force is obtained, and there is a tendency that a high attracting force can be obtained as an electrostatic attracting member.

Moreover, when the volume resistivity of the silicon carbide based sintered body 1 is in the above range, for example, when the silicon carbide based sintered body 1 is used as a member for a semiconductor manufacturing apparatus, a high electric field strength of 600 V / mm is obtained. Even when a voltage is applied, high volume resistivity can be maintained, so that reliability can be increased. In addition, there is a tendency that static electricity of the semiconductor in contact with the silicon carbide sintered body 1 is easily removed.

Further, when the volume resistivity of the silicon carbide based sintered body 1 is in the above range, for example, when used as a heat dissipation substrate, even when a voltage with a high electric field strength of 600 V / mm is applied, the volume resistivity is high. Therefore, it is possible to maintain high reliability.

The volume resistivity may be determined according to JIS C 2141-1992. Specifically, the test piece of the silicon carbide sintered body 1 for measuring the volume resistivity is a disc having a diameter and a thickness of 50 mm and 2.5 mm, respectively. What is necessary is just to obtain | require the volume resistivity when the electrode which consists of silver is formed and the voltage used as the electric field strength of 600 V / mm is applied between these electrodes.

  FIG. 2 is a schematic cross-sectional view showing an example of an electrostatic adsorption device provided with the electrostatic adsorption member of the present embodiment. In addition, the same code | symbol is used for the same member.

  The electrostatic attraction apparatus 5 in the example shown in FIG. 2 has a bipolar electrode 6 and the electrode 6 held inside, and a plate-like body 7 such as a semiconductor wafer is held on the surface by an electrostatic attraction force. The apparatus includes an electrostatic attraction member 8 made of the silicon carbide sintered body 1 of the present embodiment and a support member 10 to which the electrostatic attraction member 8 is bonded via a bonding layer 9.

  A voltage can be applied to the electrode 6 from an external power source through the lead wire 11. In the electrostatic adsorption device 5, when a voltage is applied to the electrode 6 from an external power source, static electricity is generated between the surface of the plate-like body 7 on the electrostatic adsorption member 8 side and the surface of the electrostatic adsorption member 8. The plate-like body 7 is attracted and held by electrostatic attraction force.

FIG. 3 is a schematic cross-sectional view showing an example of a plasma etching apparatus provided with the semiconductor manufacturing apparatus member of the present embodiment. In addition, the same code | symbol is used for the same member.

  The plasma etching apparatus 13 of the example shown in FIG. 3 includes a susceptor 14 on which a plate-like body 7 such as a semiconductor wafer is placed, and an annular clamp ring 15 that fixes the peripheral portion of the plate-like body 7 from above the susceptor 14. And an upper electrode 16a and a lower electrode 16b respectively provided on the upper side and the lower side of the susceptor 14, and a high-frequency power source 17 for applying a high-frequency voltage between the upper electrode 16a and the lower electrode 16b. It is a device for forming such a fine circuit.

  In the semiconductor manufacturing apparatus member of the present embodiment, for example, at least one of the susceptor 14 and the clamp ring 15 is made of the silicon carbide based sintered body 1 of the present embodiment.

  Further, the silicon carbide based sintered body 1 of the present embodiment is applied to a liner, a shower plate, a dummy wafer, a particle catcher, a focus ring, nozzles, etc. in addition to the susceptor 14 and the clamp ring 15 as a semiconductor manufacturing apparatus member. Can do.

  4A and 4B show an example of a circuit board provided with the heat dissipation board of the present embodiment, in which FIG. 4A is a plan view and FIG. 4B is a cross-sectional view taken along line A-A ′ of FIG. In addition, the same code | symbol is used for the same member.

  The circuit board 18 in the example shown in FIG. 4 is a circuit board 18 in which circuit members 20 and 21 made of metal are provided on the first main surface side of the heat dissipation board 19 made of the silicon carbide sintered body of the present embodiment. In other words, the heat dissipation board 19 and the circuit members 20 and 21 are bonded via the bonding layer 22. Note that the bonding layer 22 is made of, for example, a brazing material.

  Such a circuit board 18 can be used by mounting electronic components (not shown) on the circuit members 20 and 21. When the electronic component generates heat, the heat is exhausted by the heat dissipating substrate 19 whose main phase is silicon carbide having excellent thermal conductivity. Moreover, heat dissipation can be improved by joining the heat radiating member (not shown) which consists of metals, such as copper, for example to the 2nd main surface side which opposes a 1st main surface.

As described above, the electrostatic chucking member 8 made of the silicon carbide sintered body 1 of the present embodiment, the semiconductor manufacturing apparatus member, and the electrostatic chucking apparatus 5 using the heat dissipation substrate 19, the plasma etching apparatus 13 and the circuit board 18 are Even when a voltage with high electric field strength is applied, a high volume resistivity can be maintained, so that the reliability is high.
Next, an example of a method for manufacturing the silicon carbide sintered body 1 of the present embodiment will be described.

In order to obtain the silicon carbide based sintered body 1 of the present embodiment, first, silicon carbide powder having a purity of 98% by mass or more, preferably 99.8% by mass or more is prepared, and water and, if necessary, a dispersing agent are prepared. Are pulverized and mixed in a ball mill or bead mill for 40 to 60 hours to form a slurry. Next, with respect to 100 parts by mass of silicon carbide powder, 0.2 to 0.6 parts by mass of boron carbide powder and a sintering aid comprising lignin sulfonate and lignin carboxylate, amorphous carbon powder, or phenol resin. After adding 0.5 to 4.0 parts by mass of the agent in terms of carbon and a binder and mixing, the mixture is spray-dried to obtain granules whose main component is silicon carbide.

Here, in order to obtain the silicon carbide sintered body 1 having boron nitride as the second subphase, boron nitride having a purity of 96% by mass or more, preferably 99.8% by mass or more is used as the sintering aid. What is necessary is just to add and mix 0.1-1.0 mass part of powder with respect to 100 mass parts of silicon nitride powder. In particular, the purity of the boron nitride powder is more preferably 99.8% by mass or more.

In order to obtain a silicon carbide based sintered body 1 in which the contents of chromium, manganese, iron, cobalt, nickel, copper, vanadium, zirconium and tungsten are each 200 ppm by mass or less, chromium, manganese, iron, A silicon carbide powder in which the contents of cobalt, nickel, copper, vanadium, zirconium, and tungsten are each 200 ppm by mass or less may be used.

Next, the granules are filled into a predetermined mold and pressed and molded from the thickness direction at a pressure appropriately selected in the range of 49 to 147 MPa to obtain a molded body having a predetermined shape. The molded body is degreased in a nitrogen atmosphere at a temperature of 450 to 650 ° C. and a holding time of 2 to 10 hours to obtain a degreased body. Next, this degreased body is put in a firing furnace, and the volume ratio of inert gas: nitrogen gas = 75: 25 to 85:15, and the pressure is 0.1M.
The carbonization of this embodiment is carried out by firing at a maximum temperature of 1800 to 2200 ° C., more preferably 2100 to 2200 ° C. and holding time of 3 to 6 hours in a mixed gas atmosphere of Pa to 0.15 MPa. A silicon-based sintered body 1 can be obtained. In addition, although it does not specifically limit about an inert gas, Since acquisition and handling are easy, it is suitable to use argon gas.

  Here, silicon carbide is the main phase and has a first subphase containing carbon and nitrogen, and the nitrogen content with respect to 100% by mass of the silicon carbide based sintered body is 0.3% by mass or more and 1% by mass or less. In order to obtain the silicon carbide sintered body 1 as described above, the volume ratio of the mixed gas may be set to inert gas: nitrogen gas = 77: 23 to 83:17.

Further, the silicon carbide sintered body having a nitrogen content of 0.55 mass% or more and 1.2 mass% or less with respect to 100 mass% of the silicon carbide sintered body having the first subphase and boron nitride and the second subphase. 1 is obtained, the boron nitride powder used is 0.15 to 0.8 parts by mass, and the volume ratio of the mixed gas is an inert gas:
Nitrogen gas may be 77:23 to 83:17.

  Then, the obtained silicon carbide sintered body may be subjected to processing such as grinding or polishing on each main surface with a double-head grinding machine, a surface grinding machine or the like, if necessary. As described above, by polishing the main surface of the silicon carbide based sintered body of the present embodiment, it is possible to provide a sliding component having high insulating properties and excellent sliding characteristics.

Here, the arithmetic average height (Ra) may be measured according to JIS B 0601-2001 (ISO 4287-1997), and the measurement length and cut-off value are 5 mm and 0.8 mm, respectively.
In the case of measurement using a stylus type surface roughness meter, for example, a stylus with a stylus tip radius of 2 μm is applied to the surface of the silicon carbide sintered body 1 and the stylus scanning speed is applied. May be 0.5 mm / second.

  The silicon carbide based sintered body 1 of the present embodiment obtained by the manufacturing method described above has a first subphase containing silicon carbide as a main phase and containing carbon and nitrogen. By suppressing, high volume resistivity can be maintained even when a voltage with high electric field strength is applied.

Further, the electrostatic adsorption member and the semiconductor manufacturing apparatus member made of the silicon carbide based sintered body 1 of the present embodiment are suitable for electrostatic adsorption and removal of static electricity of a plate-like body such as a semiconductor wafer. 10 ⁷ Ω · m or more and 10 ¹⁰ Ω · m or less, and can be suitably used for these members.

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

First, silicon carbide powder having a purity of 99.8% by mass was prepared, water and a dispersant were added, and the mixture was placed in a ball mill and pulverized and mixed for 50 hours to obtain a slurry. Then, 0.4 parts by mass of boron carbide powder, 1.4 parts by mass of a phenol resin in terms of carbon, and a binder were added to 100 parts by mass of the silicon carbide powder, and the mixture was pulverized and mixed, followed by spray drying. Granules having silicon carbide as a component were obtained.

Then, the obtained granule is filled into a mold and molded by applying a pressure of 98 MPa from the thickness direction, and the obtained molded body is heated in a nitrogen atmosphere for 20 hours and held at 600 ° C. for 5 hours. Then, it was naturally cooled and degreased to obtain a degreased body. Next, the obtained degreased body was calcined at a maximum temperature of 2150 ° C. for 4 hours in an atmosphere of a mixed gas having a volume ratio of argon gas and nitrogen gas shown in Table 1 and a pressure of 0.11 MPa. By doing so, the diameter and thickness are 50mm and 3.5mm respectively.
Sample No. 1 of silicon carbide based sintered body 1 composed of a disc of mm and a prismatic body having a width, thickness and length of 4 mm, 3 mm and 40 mm, respectively. 1-7 were produced.

Also, 0.4% by mass of boron nitride, 2% by mass of a phenolic resin binder in terms of carbon, and alcohol are mixed with a silicon carbide powder having a purity of 98.0% by mass in a resin ball mill. Was prepared. By spray drying, granules containing silicon carbide as a main component were obtained.

  Then, the obtained granule is filled in a mold, molded by applying a pressure of 98 MPa from the thickness direction, and the obtained molded body is fired at 2150 ° C. for 1 hour to obtain a conventional silicon carbide sintered body. Sample No. 8 was produced. Sample No. For sample 8, sample no. As in 1 to 7, a disk and a prismatic body were produced as a set.

  Further, in order to confirm the presence or absence of the first subphase 3 contained in the silicon carbide based sintered body 1, first, each sample was thinned to a thickness of 1 mm by an ion milling method using argon (Ar) ions. Samples for observation were prepared. Then, using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer, the components of each phase are identified by setting the magnification, acceleration voltage, and observation range to 12500 times, 200 kV, 14.5 μm × 14.5 μm, respectively. The presence of subphase 3 and second subphase 4 was confirmed. The results of the presence or absence of the first subphase 3 for each sample are shown in Table 1. When the presence or absence of nitrogen in the silicon carbide phase that is the main phase 2 was confirmed using an energy dispersive X-ray spectrometer, sample No. Nos. 2 to 6 could not confirm the presence of nitrogen. 1 and 8 confirmed the presence of nitrogen.

  Further, the content of nitrogen contained in the silicon carbide sintered body 1 is determined in accordance with the chemical analysis method for fine silicon carbide powder defined in JIS R 1616-2007, and the content is shown in Table 1.

  Moreover, the relative density of the silicon carbide based sintered body 1 was determined by dividing the apparent density obtained in accordance with JIS R 1634-1998 by the theoretical density of the silicon carbide based sintered body 1. As a result, all samples had a relative density of 98%.

And both the main surfaces of the silicon carbide sintered body 1 are made of a grindstone made of diamond having a particle size number of F220 described in JIS R 6001-1998 (ISO 8486-1: 1996 and ISO 8486-2: 1996). Then, the arithmetic average height Ra specified by JIS B 0601-2001 (ISO 4287-1997) is determined by diamond abrasive grains having a particle diameter of 1 to 3 μm using a lapping machine made of tin. Polishing was performed to 0.01 μm or less, and the thickness was set to 2.5 mm.

Next, an electrode made of silver was formed on both main surfaces of the silicon carbide based sintered body 1, and a voltage with an electric field strength of 600 V / mm was applied between the electrodes in accordance with JIS C 2141-1992. The volume resistivity was measured.

In addition, the three-point bending strength of the sample is determined according to JIS R 1601-2008 (ISO 14704-2000 (MOD
)) And measured.

  Table 1 shows the measured values of volume resistivity and three-point bending strength.

  As shown in Table 1, sample No. 1 having a first subphase 3 containing silicon carbide as a main phase and containing carbon and nitrogen. Sample Nos. 2 to 6 which do not have the first subphase 3 were used. It was found that a high volume resistivity was maintained compared to 1 and 7.

In particular, Sample No. having a nitrogen content of 0.3% by mass to 1% by mass. 3-5 are
It was found that the volume resistivity was 4.8 × 10 ⁷ Ω · m or more, and the three-point bending strength was 438 MPa or more, which had high volume resistivity and high mechanical properties.

The content of the slurry prepared in Example 1 was 0.4 parts by mass of boron carbide powder with respect to 100 parts by mass of silicon carbide powder and 1.4 parts by mass of phenol resin in terms of carbon. After adding 99.8 mass% boron nitride powder and a binder, pulverizing and mixing, spray drying was performed to obtain granules whose main component is silicon carbide and whose average particle diameter is 80 μm.

And after performing molding and degreasing in the same manner as the method shown in Example 1, the volume ratio of inert gas: nitrogen gas = 79: 21 and the pressure of 0.11 MPa in a mixed gas atmosphere, By baking at a maximum temperature of 2150 ° C for 4 hours, the discs have a diameter and thickness of 50 mm and 3.5 mm, respectively, and the width, thickness and length are 4 mm, 3 mm and 40 m, respectively.
Sample No. 1 in which a plurality of each of the silicon carbide sintered bodies 1 each having a prismatic body of m was set. 9-14 were obtained.

In addition, in order to confirm the presence or absence of the first subphase 3 and the second subphase 4 contained in the silicon carbide sintered body 1, first, each sample was subjected to ion milling using argon (Ar) ions. An observation sample was prepared. Then, using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer, each observation sample was analyzed with magnification, acceleration voltage, and observation range set to 12500 times, 200 kV, 14.5 μm × 14.5 μm, respectively. Table 2 shows the results of the presence or absence of the first subphase 3 and the second subphase 4 for each sample. When the presence or absence of nitrogen in the silicon carbide phase that is the main phase 2 was confirmed using an energy dispersive X-ray spectrometer, sample No. 9-14 could not confirm the presence of nitrogen.

  Further, the content of nitrogen contained in the silicon carbide based sintered body 1 is determined using a chemical analysis method for fine silicon carbide powder defined in JIS R 1616-2007, and the content is shown in Table 2.

  Moreover, as a result of obtaining the relative density of the silicon carbide based sintered body 1 by the method shown in Example 1, the relative density of all the samples was 98%.

  The volume resistivity and three-point bending strength were measured by the method shown in Example 1, and the measured values are shown in Table 2.

  As shown in Table 2, sample no. Samples Nos. 10 to 14 were made of boron nitride, which is less likely to pass electricity than silicon carbide, due to the presence of the second subphase 4 and no second subphase 4. It was found that the volume resistivity can be maintained higher than 9.

In particular, Sample No. with a nitrogen content of 0.55 mass% to 1.2 mass% with respect to 100 mass% of the silicon carbide sintered body. Nos. 11 to 13 have a volume resistivity of 8.9 × 10 ⁷ Ω · m or more, and a three-point bending strength of 430 MPa or more, which indicates that both high volume resistivity and high mechanical properties are provided.

First, silicon carbide-based powder containing titanium and having a total ratio of 3C-type and 4H-type crystal polymorphs as shown in Table 3, water, and a dispersant for dispersing this silicon carbide-based powder are added. The mixture was pulverized and mixed for 50 hours in a ball mill to form a slurry. Then, 0.4 parts by mass of boron carbide powder, 1.4 parts by mass of a phenol resin in terms of carbon, and a binder were added to 100 parts by mass of the silicon carbide powder, and the mixture was pulverized and mixed, followed by spray drying. Granules having silicon carbide as a component were obtained.

Then, molding, degreasing, and firing were sequentially performed in the same manner as in Example 1, and sample No. 1 of silicon carbide-based sintered body 1 composed of discs having diameters and thicknesses of 50 mm and 3.5 mm, respectively. 15-19 were obtained. The relative density of this silicon carbide sintered body 1 was determined by the same method as in Example 1. As a result, the relative density of all the samples was 99%. Moreover, about the sum total of the ratio of the crystal polymorph of 3C type and 4H type of crystal polymorph, X-ray diffraction was performed using the X-ray-diffraction apparatus, and the obtained spectrum was calculated | required by the Rietveld method. Further, the volume resistivity of the silicon carbide based sintered body 1 was measured by the same method as in Example 1. The results are shown in Table 3.

  As shown in Table 3, a sample No. in which the total ratio of the 3C type and 4H type crystal polymorphs is 20% or less is used. Samples Nos. 15 to 18 are sample Nos. In which the sum of the ratios of the 3C type and 4H type polymorphs is greater than 20%. It was found that the volume resistivity value tends to be larger than 19.

1: Silicon carbide-based sintered body 2: Main phase 3: First subphase 4: Second subphase 5: Electrostatic adsorption device 6: Electrode 7: Plate-like body 8: Electrostatic adsorption member 9: Bonding layer
10: Support member
11: Lead wire
12: Adsorption layer
13: Plasma etching equipment
14: Susceptor
15: Clamp ring
16a: Upper electrode
16b: Lower electrode
17: High frequency power supply
18: Circuit board
19: Heat dissipation board
20, 21: Circuit members
22: Bonding layer

Claims (6)

The crystal of silicon carbide as a main phase, and have a first subphase containing carbon and nitrogen, the sum of 3C type and 4H-type ratio of the crystalline polymorph of the silicon carbide crystal 20% or less And having a relative density of 96.5% or more .   2. The silicon carbide based sintered body according to claim 1, wherein the content of nitrogen with respect to 100% by mass of the silicon carbide based sintered body is 0.3% by mass or more and 1.0% by mass or less.   The silicon carbide based sintered body according to claim 1, further comprising boron nitride as a second subphase.   4. The silicon carbide based sintered body according to claim 3, wherein the content of nitrogen with respect to 100 mass% of the silicon carbide based sintered body is 0.55 mass% or more and 1.2 mass% or less. An electrostatic attraction member comprising the silicon carbide sintered body according to any one of claims 1 to 4 . A member for a semiconductor manufacturing apparatus, comprising the silicon carbide sintered body according to any one of claims 1 to 4 .