| 摘要 |
PURPOSE:To shorten processing time, by a structure for a gas chamber wherein a space is formed by facing the back surface of a wafer and a porous ceramic plate so as to hold a minute gap and to surround the space, and the porous ceramic plate is bonded to the surface of a stage. CONSTITUTION:A stage 8 is constituted by an electrostatic sucking mechanism 6 and a heat sink 7. At this time, a porous ceramic plate 16 is bonded to the surface of the electrostatic sucking mechanism. The back surface of a wafer 2 is made to face the poroud alumina plate 16 with a gap a gap of 50mum being provided. A gas chamber 10 is formed together with a ring 17 at the peripheral part of the wafer 2. In this constitution, He gas, which is introduced in the gas chamber 10 does not leak in a vacuum container. In the elaborate alumina surface of the electrostatic sucking mechanism 6, projections 18 are provided at a plurality of placed. The projections 18 support the back surface of the wafer 2 by way holes opened in the porous alumina plate 16. Thus, the gap size of the gas chamber is maintained. He gas is introduced in the gas chamber, and thermal conductivity is improved. Thus the temperature increase of the wafer is remarkably suppressed, and high speed processing can be performed.
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