Electrostatic chuck
According to an aspect of the invention, there is provided an electrostatic chuck including: a ceramic dielectric substrate having a first major surface, a second major surface, and a through-hole; a metallic base plate which has a gas introduction path that communicates with the through-hole; and a bonding layer which is provided between the ceramic dielectric substrate and the base plate and includes a resin material, the bonding layer having a space which is provided between an opening of the through-hole in the second major surface and the gas introduction path and is larger than the opening in a horizontal direction, and a first area in which an end face of the bonding layer on a side of the space intersects with the second major surface being recessed from the opening further than another second area of the end face which is different from the first area.
1. An electrostatic chuck comprising:
a ceramic dielectric substrate having a first major surface on which an object to be adsorbed is placed, a second major surface on an opposite side to the first major surface, and a through-hole provided over from the second major surface to the first major surface;
a metallic base plate which supports the ceramic dielectric substrate and has a gas introduction path that communicates with the through-hole; and
a bonding layer which is provided between the ceramic dielectric substrate and the base plate and includes a resin material,
the bonding layer having a space which is provided between an opening of the through-hole in the second major surface and the gas introduction path and is larger than the opening in a horizontal direction, and
a first area in which an end face of the bonding layer on a side of the space intersects with the second major surface being recessed from the opening further than another second area of the end face which is different from the first area.
2. The chuck according to claim 1 , wherein in the first area when viewed in a direction perpendicular to a normal to the second major surface, an angle between the second major surface and the end face becomes larger toward the second major surface.
3. The chuck according to claim 2 , wherein a third area in which an angle between the second major surface and the end face becomes smaller with distance from the second major surface in a direction of the normal is provided.
4. The chuck according to claim 1 , wherein a distance between the end faces facing each other becomes shorter with distance from the second major surface in a direction of the normal.
5. The chuck according to claim 1 , wherein in a distance d between the end face in the first area and a center of the through-hole and a distance D between the end faces facing each other in the second area, a relational expression of 2d≧D is established.
6. The chuck according to claim 5 , wherein the distance d is 0.1 millimeters or more and 5.0 millimeters or less.
7. The chuck according to claim 5 , further comprising:
a porous body provided in the gas introduction path,
wherein in the distance d and a radius R of the porous body, a relational expression of d>R is established.
8. The chuck according to claim 5 , wherein the distance d is larger than a radius of an opening of the through-hole on a side of the first major surface.
9. The chuck according to claim 1 , wherein the bonding layer has
a bonding portion which bonds the second major surface and the base plate together, and
an end portion which has the end face and forms the space, and
a material of the bonding portion is different from a material of the end portion.
10. The chuck according to claim 9 , wherein thermal conductivity of an adhesive which is used in the bonding portion is 0.1 watts/meter·kelvin or more,
dielectric breakdown strength of an adhesive which is used in the bonding portion is 1 kilovolt/millimeter or more, and
a heat resistance temperature of an adhesive which is used in the bonding portion is 40° C. or more.
11. The chuck according to claim 9 , wherein the end portion comes into contact with each of the second major surface and the base plate in a plane, and
a length in the horizontal direction of the plane in which the end portion comes into contact with each of the second major surface and the base plate is longer than a thickness of the bonding layer.
12. The chuck according to claim 11 , wherein an outer peripheral portion of the end portion, the outer peripheral portion being on an opposite side to the space when viewed from the end portion, is filled with the resin material.
13. The chuck according to claim 11 , wherein a plane in which the second major surface comes into contact with the end portion is on a same plane as a plane in which the second major surface is bonded by the bonding layer, and
a plane in which the base plate comes into contact with the end portion is on a same plane as a plane in which the base plate is bonded by the bonding layer.
14. The chuck according to claim 11 , wherein curvature of the end face in the first area is larger than curvature of the end face in the second area.
15. The chuck according to claim 1 , wherein the bonding layer has
a bonding portion which bonds the second major surface and the base plate together, and
an end portion which has the end face and forms the space, and
a material of the bonding portion is the same as a material of the end portion.
16. The chuck according to claim 1 , wherein a length in the horizontal direction of the space is longer than a thickness of the bonding layer.
17. The chuck according to claim 1 , wherein the ceramic dielectric substrate includes a Coulomb material having volume resistivity of 1×10 14 ohm·centimeter or more.