Thermal conductivity of CMOS materials for the optimization of microsensors

Abstract

The authors have measured the thermal transport properties of four different material layers as produced by a commercial IC CMOS process (AMS, Austria Mikro Systeme). The thermal conductivities of two differently doped polycrystalline silicon layers, of a silicon dioxide isolation layer, and of one metal layer are reported in the temperature range from 100 to 420 K. The characterization was carried out with specially designed microelectromechanical test structures. At room temperature, the thermal conductivities of the n- and p-doped polysilicon layers were found to be 29 and 18 W K^-1 m^-1, respectively. These values represent a significant decrease from the 156 W K^-1 m^-1, of high-purity monocrystalline bulk silicon. The thermal conductivities of silicon dioxide and of the first aluminium metallization layer were determined as 1.15 and 180 W K^-1 m^-1, at 300 K, which are close to known bulk values.