Patent ID: 11887873
Assignee: NGK INSULATORS, LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 3:
4. A wafer placement apparatus comprising:
a ceramic plate having an upper surface as a wafer placement surface and in which an electrode is embedded; and
a cooling plate provided on a lower surface, opposite the wafer placement surface, of the ceramic plate and a refrigerant passage is provided in the cooling plate, wherein
the refrigerant passage includes a first passage and a second passage, with each passage forming a single continuous line having an overall length that extends between a respective inlet and outlet of the passage, the first passage and the second passage extend along a single common plane that is parallel to the wafer placement surface so as to have an uppermost axial surface of both the first and the second passages be at a same axial distance from the wafer placement surface, and the first and the second passages are formed directly adjacent to each other as a pair that have a substantially same size radial gap therebetween that extends across an entirety of the overall length of the first and the second passages, which includes the respective inlet and outlet of the first and the second passages,
the inlet of the first passage, the outlet of the second passage, the inlet of the second passage, and the outlet of the first passage are linearly adjacent to one another in that order in a central part of the cooling plate, and
the first passage forms a line running over the entirety of a region of the cooling plate over which the ceramic plate spreads.