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VACUUM CHUCKS AND OTHER VACUUM TOOLS TO HANDLE SEMICONDUCTOR WAFERS HAVING THROUGH HOLES OR PERFORATIONS

IP.com Disclosure Number: IPCOM000027003D
Original Publication Date: 1994-Dec-31
Included in the Prior Art Database: 2004-Apr-07
Document File: 4 page(s) / 154K

Publishing Venue

Xerox Disclosure Journal

Abstract

Most wafer handling equipment used by the semiconductor industry to hold a wafer rely on vacuum forces. Examples are (1) round chucks with vacuum rings on to which wafers are placed for tight x, y, z, and theta movement and rotation control during layer alignment to a mask before photoresist exposure, and (2) transfer arms which load and unload single wafers from cassettes. In most cases, the wafer surface is flat and contains no holes, thereby providing a good surface for vacuum hold down. Sometimes, a small vacuum leak may be present due to warpage, cracks, or other problems, but which can still hold the wafer without interrupting the function being performed. If this leak becomes too large however, such as when the chuck or wafer surface is severely distorted, no vacuum seal occurs and the hold down or transfer function becomes interrupted.

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XEROX DISCLOSURE JOURNAL

Proposed Classification
U.S. C1.156/155 Int. C1. B32b 31/100

VACUUM CHUCKS AND OTHER VACUUM TOOLS TO HANDLE SEMICONDUCTOR WAFERS HAVING THROUGH HOLES OR PERFORATIONS
Robert E. Proano
James F. O'Neill

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XEROX DISCLOSURE JOURNAL - Vol. 19, No. 6 November/December 1994 435

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VACUUM CHUCKS AND OTHER VACUUM TOOLS TO HANDLE SEMICONDUCTOR WAFERS HAVING THROUGH HOLES OR PERFORATIONS(Cont'd)

Most wafer handling equipment used by the semiconductor industry to hold a wafer rely on vacuum forces. Examples are (1) round chucks with vacuum rings on to which wafers are placed for tight x, y, z, and theta movement and rotation control during layer alignment to a mask before photoresist exposure, and (2) transfer arms which load and unload single wafers from cassettes. In most cases, the wafer surface is flat and contains no holes, thereby providing a good surface for vacuum hold down. Sometimes, a small vacuum leak may be present due to warpage, cracks, or other problems, but which can still hold the wafer without interrupting the function being performed. If this leak becomes too large however, such as when the chuck or wafer surface is severely distorted, no vacuum seal occurs and the hold down or transfer function becomes interrupted.

Thermal ink jet printers of one known type have a printhead that is fabricated by dicing and separating a bonded heater wafer and channel wafer pair. Prior to wafer bonding, each set of heating elements and driving circuitry on the heater wafer and each set of ink flow passageways in the channel wafer is tested against its design specifications: electrical for the heater wafer and mechanical for the channel wafer.

The channel plate for thermal ink jet printhead applications is designed to have etched "channel" grooves and "ink fill" wafer through holes, both of which are fabricated using orientation dependent etching. There is at least one hole for each of the many die on a wafer that are spaced throughout the entire surface and penetrate through the wafer thickness on to the back, providing openings of approximately 0.35- x 3.5mm each. These holes interfere with the vacuum ports in normally designed chucks and other wafer handling equipment, thereby making the wafers impossible to handle reliably. Requirements to handle wafers (and other material parts) which contain perforations through the surface need equipment which consistently avoids placing the interrupti...