Observed effects of sapphire substrate preparation on the subsequent electrical and radiation performance of CMOS/SOS devices

Summary form only given. Sapphire substrates 100 mm in diameter obtained from both Union Carbide Corporation (UC) and Kyocera Corporation were used. Epitaxial silicon was deposited on these substrates according to proprietary radiation-hard specifications. Once deposited, the epitaxial silicon films were examined by ultraviolet reflectometry (UVR), which detected substrate influences. The UC substrates with the lowest residual surface damage grew the best epitaxial film, while the samples that got only a cursory polish showed a large range of values. The overpolished UC samples and the Kyocera substrates were in-between and practically identical. Test devices were fabricated and subjected to extensive parametric and radiation testing and characterization. Marked differences between the two brands of substrates and between the various preparations were discovered. Radiation testing was performed at the wafer level to a total dose of 200000 Rad(Si). The results demonstrated that physical and electrical similarities are no guarantee of commensurate radiation-hardness