Improvement in GaAs Device Yield and Performance through Substrate Defect Gettering
Abstract
The gettering of Cr and front-surfaces defects by mechanically produced back-surface damage in semi-insulating GaAs wafers has been investigated. It has been shown that improved VPE layers can be grown on pre-gettered substrates. Also, the level of Cr outdiffusing from the substrate during epilayer growth and subsequent annealing is substantially reduced when pre-gettered substrates are used. Thermal stability times of back-surface damage at an anneal temperature of 800 C is typically on the order of 2 - 3 hours, corresponding to the point at which major back-surface microstructural damage is largely annealed. Increases in the thermal stability period were attained by encapsulating the back surface with an As-doped SiO2 layer. Subsequent investigations of Au contacts on GaAs showed that Cr was mobile during 350 C alloying, resulting in gettering within alloy damage regions and subsequent outdiffusion into the Au film. Device structures (FET) fabricated on VPE layers on pre-gettered GaAs wafers showed considerable improvements in both yield/ wafer, noise figures at higher frequencies and input capacitance values.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1980
- Accession Number
- ADA081344
Entities
People
- Jing Peng
- Jonathan Hong
- R. A. Armistead
- T. J. Magee