A bulk silicon SOI process for active intevated sensor

Abstract

This paper reports a process for the formation of very high quality single-crystal silicon films on glass substrates. The process utilizes the electrostatic bonding of silicon and glass wafers, with subsequent etching of the silicon to form siliconon-insulator (SOI) films having thicknesses controlled from less than 2.[mu]m to over 20,[mu]m with better than 10% uniformity. The use of Corning type 1729 glass substrates yields an excellent thermal expansion match to the silicon film and allows the use of post-bond processing temperatures as high as 850 [deg]C, permitting the formation of both transducer and transistor structures in the film after bonding and etch-back. Thus, the process offers one means of integrating MOS or bipolar circuitry into dissolved-wafer sensing structures. MOS devices formed in such films show characteristics similar to those in standard bulk silicon, including n-channel mobilities of 640 cm2/V s, the highest ever reported for SOI on glass. A variety of related processes are also possible, where some or all of the high-temperature silicon device processing is performed before bonding to the glass substrate.