Thickness Measurement Technology for Thin Films on Sapphire Substrate

Silicon-on-sapphire (SOS) integrated circuits have achieved popularity due to their high speed performance and low power consumption in radio frequency applications. An important aspect of the SOS fabrication process that must be verified to maximize yield is the thickness of the thin films deposited on the sapphire substrate. However, due to the transparent nature of sapphire, current optical metrology tools are not applicable. In a Small Business Technology Transfer (STTR) Phase I, Advanced Cooling Technologies, Inc. (ACT) has developed and demonstrated an easy-to-use, non-contact and non-destructive instrument for performing thin film thickness measurements for SOS and related materials. This technique uses a novel alternative spectrographic technique to quickly and accurately determine thin film thicknesses with extreme accuracy. The proposed STTR Phase II program will further develop and mature the measurement methodology, and a full-scale instrument that can be integrated into an SOS wafer fabrication process will be designed and built.