High-temperature thermal sensor based on ultra-thin silicon film for ultra-low-power applications

A thermal sensor built from a silicon resistor with a simple rectangular layout structure on thin-film (0.1 mum) silicon-on-insulator (SOI) substrate is studied and compared with those on thick-film (10 gm) SOI and bulk (450 pm) Si. Besides supporting the theory of minority-carrier exclusion effect through one-dimensional highly confined carrier transport in the ultra-thin rectangular silicon film, the thin-film SOI device demonstrates the effect of silicon-film thickness on the maximum operating temperature (T-max) of the sensor: thinner Si film results in higher Tmax due to higher current density and hence stronger exclusion effect. Measurements and simulations both show that the SOI structure can indeed have the silicon-film thickness as an additional degree of freedom for increasing T-max. More importantly, the thin-film SOI thermal resistor can achieve a Tmax beyond 400 C even under a very low operating current of 0.1 muA, which is about 1000 times smaller than that of the thick-film SOI counterpart with the same T-max. In conclusion, silicon resistor on SOI is a promising low-cost thermal sensor for a broad scope of low-power high-temperature applications. (C) 2003 Published by Elsevier Science Ltd.