Browse Prior Art Database

Production Step X Repeat Table for Wafer Exposure

IP.com Disclosure Number: IPCOM000076828D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 75K

Publishing Venue

IBM

Related People

Santy, WG: AUTHOR [+2]

Abstract

The drawing shows a production step and repeat table for positioning a semiconductor wafer mounted on a stage in X and Y directions. The table includes the stage, which is mounted on slides such that the stage can be moved in the X direction on one set of slides and the Y direction on the other set of slides. Four stepping motors are provided, two for the X direction and two for the Y direction. The motors are connected through gear trains to screw drives which drive the slides through cushions of compressed air.

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Production Step X Repeat Table for Wafer Exposure

The drawing shows a production step and repeat table for positioning a semiconductor wafer mounted on a stage in X and Y directions. The table includes the stage, which is mounted on slides such that the stage can be moved in the X direction on one set of slides and the Y direction on the other set of slides. Four stepping motors are provided, two for the X direction and two for the Y direction. The motors are connected through gear trains to screw drives which drive the slides through cushions of compressed air.

The production step and repeat table utilizes PYREX* ways and air bearings throughout. It is arranged in conventional X-Y stage manner. However, for inherent positional accuracy and repeatability of stepping, it utilizes a set of gauge blocks 10 made also out of PYREX and an air probe 12 locking device. The drive of both tables is by stepping motors and actuating screws, which in turn drive the table through a cushion of air. One paid is rigidly mounted to the slide, while the other rotates with the drive screw. Every slide is equipped with two identical driving assemblies to maintain balance and accurate stepping to within 0.000080 inch. The final positioning is accomplished by the air probe device 12, the probe of which is free to rotate into the slot of the gauge blocks. The probe has two orifices, allowing a balance of air pressure to be maintained between both sides of the probe and adjacent gauge block surfaces. The clearance between the air probe and gauge block surfaces is of the order of
0.000100 inch on either side at the beginning of engaging, and with the increase of rotation of the probe it is reduced to about 0.000050 inch. At that point, the air pressure is completely removed from the driving pads and the air probe takes over and completes the table positioning.

The principle of operation and locking in position of both axial motions is the same. The wafer carries two fiducial marks. One of them is fixed above the point of rotation of the wafer holding assembly located close to the wa...