| 摘要 |
This patent discloses apparatus for accurately aligning a semiconductor wafer to a photo mask, the apparatus disclosed comprising a base and a frame for the apparatus. The base portion includes a chamber in which is mounted a piston which is restrained from lateral movement while permitting vertical reciprocation thereof. In the upper portion of the piston is a socket which supports a gimbal, the gimbal including means for receiving a wafer thereon. Mounted on the frame is a carriage which includes means for positioning a mask in superimposed overlapping relation relative to the gimbal while clamping the mask to the frame. Also disclosed is fluid supply means which is connected to the socket so that the gimbal will float on a cushion, for example, of air. The piston is provided with elevating means to cause the piston to raise beyond the point of contact of a wafer mounted on the gimbal with the mask. Also disclosed is means responsive to the increase in fluid pressure which results from the contact of the wafer with the mask for stopping the elevating means and thus the piston. Thereafter the piston is lowered a preset and predetermined amount to thereby space the wafer from the mask permitting adjustment of the base relative to the frame.
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