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

Abstract

A thermal sensor built from a silicon resistor with a simple rectangular layout structure on thin-film (0.1 μm) silicon-on-insulator (SOI) substrate is studied and compared with those on thick-film (10 μm) SOI and bulk (450 μm) 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 T max 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 T max beyond 400 °C even under a very low operating current of 0.1 μA, 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.