Fabrication of sensors and microsystems on SIMOX substrates

SIMOX substrates are fabricated by high dose oxygen implantation into the silicon and subsequent high temperature annealing so generating a buried oxide layer. The implantation can be masked, resulting in local regions of buried oxide. The buried oxide has similar properties as thermally grown oxide and the surface silicon layer has a low defect density. The buried oxide layer can be used as an etch stop layer for anisotropic etching from the wafer backside resulting in silicon membranes with a well controlled thickness in the range of 250 nm to 20 mym. These membranes can be used for e.g. thermal isolation of devices or for mechanical devices and as oscillating membranes etc. In addition the membrane is from undoped crystalline silicon enabling the fabrication of integrated electronic circuitry. We present results on process technology and experimental data on sensors fabricated on SIMOX subtrates.