Among the technologies for integrating GaAs devices with Si VLSI chips, epi
taxial liftoff (ELO) is conspicuous for maintaining the quality of the sing
le crystal epitaxial GaAs films. Traditionally, ELO is implemented in aqueo
us HF solution. It would be cleaner and simpler if ELO could be implemented
in a vapor process. In this article, we will present the potential improve
ments in the ELO process by using a vapor phase etch to undercut thin films
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