Browse Prior Art Database

Semiconductor Leveling System

IP.com Disclosure Number: IPCOM000080968D
Original Publication Date: 1974-Mar-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Buechele, JW: AUTHOR

Abstract

To achieve precise line definition on semiconductor wafer chips, it is desirable that the distance of the lens optical path be precisely regulated and controlled, to insure proper focusing of the projected image on the chip site.

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Semiconductor Leveling System

To achieve precise line definition on semiconductor wafer chips, it is desirable that the distance of the lens optical path be precisely regulated and controlled, to insure proper focusing of the projected image on the chip site.

Referring to the drawings, wherein a leveling and focusing system 10 is shown, the system comprises a leveling plate 11 which is mounted for reciprocation on three hydraulically actuated hydraulic drivers 12 (only two being illustrated in the drawing) approximately 120 Degrees apart. The hydraulic drivers are mounted by dual diaphragms 13 and 14 to insure lateral stability of the leveling plate, and to form a hydraulic chamber 15 under the lowermost diaphragm 14.

A highly accurate and level chuck cup 16 having a plurality of annular knife edge-like projections 17, with central vacuum sources therein, serve to flatten the wafer against the knife edge-like surfaces. A sensing head 18 includes air sensors 19 which are disposed circumferentially about a central aperture 20, defining an optical path for projection printing on the surface of the wafer 21. The sensors 19 operate in a conventional manner to determine focus distance from the ends of the sensors, and measure the flatness of the wafer for parallelism. The sensors 19 are pneumatic and work in conjunction with pressure differential switches, not shown. If the wafer is not parallel to the focus plane, the sensors 19 will so indicate by giving a feedback s...