Micromachined CMOS thermoelectric generators as on-chip power supply

As the power consumption of a large number of microelectronic devices has been continuously reduced in recent years, power supply units of a few microwatts have become sufficient for their operation. Our improved micro-scale thermoelectric generator (/spl mu/-TEG) is based on polysilicon surface micromachining and is designed to convert waste heat into electrical power. Since this device is compatible with standard CMOS fabrication processes, it can be easily integrated on chip level and matches the needs for low-cost and small-size systems. As thermoelectric materials, both, pure poly-Si and poly-Si/sub 70%/Ge/sub 30%/ have been investigated. Emphasis was placed on a thermally optimized design and the reduction of the total electrical resistance of the generator. As a result of these improvements, a voltage of 5 V and an electrical power output of 1 /spl mu/W for a matched consumer is achieved with generators of 1 cm/sup 2/ in size at a temperature drop of about 5 K.