Controlled Atmosphere Annealing of Ion Implanted Gallium Arsenide.

Controlled atmosphere techniques were developed as an alternative to dielectric encapsulation for the high temperature anneal of ion implanted layers in GaAs. Two approaches 1 the controlled atmosphere technique CAT, and 2 the melt controlled ambient technique MCAT have been investigated. Using the CAT procedure, which involves annealing in flowing hydrogen with an arsenic overpressure, annealing without detectable surface erosion, has been performed at temperatures as high as 950 C, with or without encapsulants. Impurity diffusion, damage recovery, and electrical activity were investigated as a function of anneal parameters. Range studies of technologically important impurities such as S, Si, Se, Be and Mg were carried out. For the first time the role of the encapsulant on implanted profile degradation and the importance of Cr redistribution during the anneal cycle were determined. An improved CAT anneal system capable of production quantity throughput was developed and is in current use for device processing. Author