Ultra-Low-Temperature Process Modules for Back-Wafer-Contacted Silicon-on-Glass RFIMicrowave Technology

This paper reviews several novel process modules developed for the processing of the backside of the wafer of our substrate-transfer technology called back-wafer-contacted silicon-on-glass (SOG), which is in use for fabricating RF/microwave devices such as high-quality varactors and bipolar transistors. In this technology the silicon wafer is transferred to glass by gluing. The integrity of the acrylic adhesive limits the subsequent processing temperatures to less than 300°C. Ultra-low-temperature process modules have therefore been developed to nevertheless allow the creation of low-ohmic contacts and high-quality ultrashallow junctions. Moreover, a physical-vapor deposition of AIN provides an effective means of integrating a thin-film dielectric heatspreader. 1