TWO-STEP ANNEALING PROCESS FOR GaAs MESFET FABRICATION
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
This article describes an anneal process for GaAs MESFET fabrication which reduces Si3N4 film delamination caused by formation of blisters and bubbles on the wafer surface during Si3N4 capped anneal. The wafer is first annealed at a low temperature (preferably in the range of 400-600ŒC) in a conventional furnace to drive out hydrogen (and/or other) gases from the Si3N4 film. The wafer is then raised to a higher temperature, e.g., 800-1100ŒC for dopant activation and diffusion. This second anneal can be done either in a conventional furnace or by the rapid annealing method. Fig. 1 illustrates the bubbling and delamination problem associated with the conventional process. Fig. 2 illustrates the improvement obtained in the film surface by use of the two-step annealing process herein disclosed. In Fig.