P A P E R    T I T L E
Alternate Backside Thinning of GaAs-Based Devices

A U T H O R  /  C R E D I T S
R. J. Olson, Jr., M. F. Taylor, R. J. Williams, T. S. Faska and M. Sundaram Sanders, A Lockheed-Martin Company 65 Spit Brook Road, Nashua, NH 03060

Lapping continues to offer some advantages over wafer grinding for backside thinning of GaAs substrates. Lapping systems are widely used to successfully thin 3" and 4" GaAs wafers, but until now, no studies have been published on larger wafers. The feasibility of lapping 150mm (6") GaAs wafers is investigated using a new precision lapping and polishing jig developed by Logitech Ltd. We also describe a procedure that successfully automates wax bonding to a temporary support disc. We find that 150mm wafers can be reliably thinned to thickness of less than 100 microns (4 mils) using a lapping process and discuss the impact of wax mounting, thickness control, wafer flatness and parallelism on wafer yields.