Composite sintered body, electrostatic chuck member, electrostatic chuck device, and method for producing composite sintered body
A composite sintered body is a ceramic composite sintered body which includes metal oxide which is a main phase, and silicon carbide which is a sub-phase, in which crystal grains of the silicon carbide are dispersed in crystal grains of the metal oxide and at crystal grain boundaries of the metal oxide, and a proportion of the crystal grains of the silicon carbide dispersed in the crystal grains of the metal oxide is 25% or more in an area ratio with respect to a total crystal grains of the silicon carbide.
1. A composite sintered body which is a ceramic composite sintered body, comprising:
a metal oxide which is a main phase; and
silicon carbide which is a sub-phase,
wherein crystal grains of the silicon carbide are dispersed in crystal grains of the metal oxide and at crystal grain boundaries of the metal oxide, and
a proportion of the crystal grains of the silicon carbide dispersed in the crystal grains of the metal oxide is 25% or more in an area ratio with respect to a total crystal grains of the silicon carbide.
2. The composite sintered body according to claim 1 , wherein the metal oxide is aluminum oxide or yttrium oxide.
3. The composite sintered body according to claim 1 , wherein an average crystal grain size of the metal oxide is 1.2 μm or more and 10 μm or less.
4. An electrostatic chuck member comprising:
a plate-shaped base which is formed of, as a forming material, the composite sintered body according to claim 1 , the base having one principal surface which is a placing surface on which a plate-shaped sample is placed; and
an electrostatic attraction electrode provided on a side opposite to the placing surface of the base, or in an interior of the base.
5. An electrostatic chuck device comprising:
the electrostatic chuck member according to claim 4 .
6. A method for producing a composite sintered body, comprising:
a step of mixing metal oxide particles and silicon carbide particles;
a step of adjusting pH of slurry obtained in the mixing step to a range in which surface charges of the metal oxide particles in the slurry become positive and surface charges of the silicon carbide particles in the slurry become negative;
a step of forming a formed body after a dispersion medium is removed from the slurry with adjusted pH; and
a step of pressure-sintering the obtained formed body by heating the formed body to a temperature of 1600° C. or higher while compacting the formed body with a pressure of 25 MPa or more under a non-oxidative atmosphere.
7. The method for producing a composite sintered body according to claim 6 , wherein the step of mixing metal oxide particles and silicon carbide particles is a step of mixing metal oxide particles and silicon carbide particles while causing the metal oxide particles and the silicon carbide particles to collide with each other by injecting the metal oxide particles and the silicon carbide particles at high speed.
8. The method for producing a composite sintered body according to claim 6 , further comprising:
a step of oxidizing surfaces of the silicon carbide particles, prior to the mixing step.
9. The method for producing a composite sintered body according to claim 6 , wherein the step of adjusting pH makes the pH of the slurry 3 or more and 7 or less.
10. The method for producing a composite sintered body according to claim 6 , wherein the metal oxide particles have a metal oxide content of 99.99% or more.
11. The composite sintered body according to claim 1 , wherein the proportion of the metal oxide in the entire composite sintered body is 92% by mass or more.
12. The composite sintered body according to claim 1 , wherein the proportion of the silicon carbide in the entire composite sintered body is 8% by mass or more.
13. The composite sintered body according to claim 1 , wherein the silicon carbide which is included in the composite sintered boy is β-SiC.
14. The composite sintered body according to claim 13 , wherein the volume ratio of the β-SiC is 4% by volume or more and 15% by volume or less with respect to the entire composite sintered body.