Wafer placement table
A wafer placement table includes an alumina base that has a wafer placement surface on its upper surface, and incorporates an electrode; a brittle cooling base bonded to a lower surface of the alumina base; and a ductile connection member stored in a storage hole, opened in a lower surface of the cooling base, in a state of restricted axial rotation and in a state of engaging with an engagement section of the storage hole, the ductile connection member having a male thread section or a female thread section.
1. A wafer placement table comprising:
an alumina base that has a wafer placement surface on its upper surface, and incorporates an electrode;
a brittle cooling base bonded to a lower surface of the alumina base; and
a ductile connection member stored in a storage hole, opened in a lower surface of the cooling base, in a state of restricted axial rotation and in a state of engaging with an engagement section of the storage hole, the ductile connection member having a male thread section or a female thread section; and
wherein the engagement section is a step section or an inclined section provided in an inner circumferential surface of the storage hole, and
the connection member has a to-be-engaged section which engages with the engagement section to prevent the connection member from falling from the storage hole.
2. The wafer placement table according to claim 1 ,
wherein the connection member is a member having the female thread section, and being screwable to a male thread of a bolt inserted from a lower surface side of the cooling base.
3. The wafer placement table according to claim 1 ,
wherein the cooling base is composed of a composite material of metal and ceramic or an alumina material.
4. The wafer placement table according to claim 1 ,
wherein when being attempted to be axially rotated, the connection member comes into contact with a wall of the storage hole to undergo restricted axial rotation.
5. The wafer placement table according to claim 1 ,
wherein the cooling base has a refrigerant flow path internally, and
the storage hole is provided in a region of the cooling base, the region being lower than a bottom surface of the refrigerant flow path.
6. The wafer placement table according to claim 1 ,
wherein the connection member is not bonded to the cooling base in the storage hole, and is stored in a free state.
7. The wafer placement table according to claim 1 ,
wherein the connection member engages with the engagement section with a stress buffering member interposed between the connection member and the engagement section, the stress buffering member having a Young's modulus lower than a Young's modulus of the connection member.
8. The wafer placement table according to claim 1 ,
wherein a gap between the connection member and the storage hole is filled with a filling material.
9. The wafer placement table according to claim 1 ,
wherein the storage hole includes a first storage section that stores the connection member, and a second storage section provided from the first storage section to the lower surface of the cooling base, and
the engagement section is a stepped surface provided at a joint between the first storage section and the second storage section.
10. The wafer placement table according to claim 9 ,
wherein the first storage section is opened in an upper surface of the cooling base, and an opening surface is covered by a bonding layer that bonds the alumina base and the cooling base.
11. The wafer placement table according to claim 9 ,
wherein a width of an annular region in which the stepped surface is in direct or indirect contact with the connection member is 3 mm or more.