Browse Prior Art Database

Wafer Chuck

IP.com Disclosure Number: IPCOM000040377D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 113K

Publishing Venue

IBM

Related People

Brown, RE: AUTHOR [+4]

Abstract

Semiconductor wafers are rigidly vacuum clamped during photoresist exposure operations to minimize registration errors. While accomplishing this task, conventional wafer chucks cause undesired, non-linear, random variations of chucked wafer flatness (due to friction effects between the wafer and chuck surface during the clamping cycle). In turn, these cause lateral distortions of the wafer surface and (after exposure) of the etched pattern arrays. This wafer chuck overcomes these problems, substantially reducing overlay errors pertaining to wafer-chucking tolerances. The drawing shows the basic design appearing "on the surface" of this wafer chuck. Several features of the improved chuck design minimize registration errors as follows: (1) The ratio between groove (i.e.

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Wafer Chuck

Semiconductor wafers are rigidly vacuum clamped during photoresist exposure operations to minimize registration errors. While accomplishing this task, conventional wafer chucks cause undesired, non-linear, random variations of chucked wafer flatness (due to friction effects between the wafer and chuck surface during the clamping cycle). In turn, these cause lateral distortions of the wafer surface and (after exposure) of the etched pattern arrays. This wafer chuck overcomes these problems, substantially reducing overlay errors pertaining to wafer-chucking tolerances. The drawing shows the basic design appearing "on the surface" of this wafer chuck. Several features of the improved chuck design minimize registration errors as follows: (1) The ratio between groove (i.e., vacuum) region 1 to wafer contact region 2 is greater than one, and the grooves are spaced

close together to increase the likelihood of trapping particles.

(2) The vacuum chuck is made of silicon carbide (98

R/C), a material whose coefficient of expansion is

close to that of the silicon wafer.

(3) The machined flat surface of the chuck is coated

with titanium nitride using ion bonding to provide

advantages to wafer chucking, including scratch

resistance (hardness), abrasion resistance, and, most

importantly, low friction between wafer and chuck

surface during the clamping cycle.

(4) A portion of the chuck surface (the center portion

3 in the drawing) can be removed and replaced by a

cor...