1989 年 55 巻 1 号 p. 81-86
Reduction projection aligner needs a noncontact measurement means for the position of the wafer surface. A pneumatic gauge is suitable to detect the position of the wafer surface coated with several materials. The pneumatic gauge for this purpose has large outlet diameter which equals the reduction projection area. It must work under large operation gap and at the same time extremely low flow rate for semiconductor process. In this paper, design method and accuracy of the noncontact positioning apparatus with the large-outlet pneumatic gauge and some experimental results are described. Main results obtained are as follows: (1) Positioning accuracy depends mainly on pressure transducer accuracy. (2) Developed apparatus having a 20 mm outlet diameter, and a 90 μm gap, has achieved a positioning acuracy of 0.08 μm (3σ) under low flow rate (0.4l/min).