Rapid thermal annealing of gallium arsenide with trimethyl arsenic overpressure

摘要

A method of annealing a wafer in a rapid thermal annealer is disclosed. The walls of the chamber are heated more rapidly than is the wafer. In a preferred embodiment, the interior of the graphite walls of the annealer is lined with a molybdenum sheet which is open toward the lamps that heat the chamber. Thus, the walls heat very rapidly to a temperature greater than the condensation point of arsenic, preventing arsenic condensation on the walls. Effective annealing can be achieved at wall temperatures in the range of 500° to 600° C. Prior to the heat ramp up, an arsenic atmosphere, preferably trimethylarsenic (TMAs) at an appropriate overpressure is introduced. This overpressure is maintained both during the heating and cooling cycle. By the use of this method, the exposure time for annealing can be reduced from prior times of as much as 20 minutes to as little as 10 seconds.