Browse Prior Art Database

WAFER EDGE STRENGTH TESTER

IP.com Disclosure Number: IPCOM000005774D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2001-Nov-05
Document File: 2 page(s) / 95K

Publishing Venue

Motorola

Related People

George Wayne Hawkins: AUTHOR

Abstract

This system passes the edge of a semiconductor wafer under a roller to bend it and records the wafer breakage as a function of load and angle around the wafer.

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MO7VROLA Technical Developments Volume 9 August 1989

WAFER EDGE STRENGTH TESTER

by George Wayne Hawkins

This system passes the edge of a semiconductor wafer under a roller to bend it and records the wafer breakage as a function of load and angle around the wafer.

   The systems consists of a plastic covered semiconductor wafer held on a rotating motorized vacuum chuck, covered with a thin layer of medium durometer rubber. A tilted roller carried on a balanced lever system is pressed on the wafer edge by an air cylinder, whose pressure is controlled by an accurate regulator. The sounds of wafer breakage are picked up by a microphone placed near the roller, processed by a high pass filter and rectifier and recorded by a chart recorder which acts as a low pass filter.

   In operation, the wafer is covered on both sides with adhesive plastic film, centered on the vacuum chuck and held down by vacuum. The roller is located at the corner of the major flat for angle orientation. The chuck rotates slowly, passing the edge of water under the roller at a constant speed. The roller bends the wafer into the soft layer and creates tensile stress in the lower edge. When the wafer breaks, the noise is converted to a pulse and recorded. The time translates to angle location on the wafer and the force applied translates to stress at fracture. The wafer pieces are retained by the plastic film as the test continues. The load is raised for each new revolution. The data is summarized by counting breaks at each load, calculating the angular position of breaks from the chart recording, and by observing the fracture origin sites through the transparent plastic film. When the roller passes over already broken areas, there may be additional breakage but the noise level is much lower than that of the initial breaks.

   The advantages of th...