Development of thermoelectric energy generator with high area density stacked polysilicon thermocouples

Abstract

A semiconductor thermoelectric energy generator (TEG) with thermocouples in high area density is proposed in this work. Different from the common TEGs with co-planar thermocouples, the high area density is achieved by placing the P-thermoleg above the N-thermoleg into a stacked thermocouple, which is then insulated above and below by double cavity to retain sufficient thermal gradient. The TEG voltage factor is therefore increased by a factor of 2. For a TEG implemented by standard CMOS process (TSMC D35 2P4M), simulation shows that the stacked thermocouple of size 58 × 2 × 0.180 µm P-type thermoleg above 64 × 2 × 0.275 µm N-type thermoleg can reach optimal performance. Measurement results of a 5 × 5 mm2 TEG chip by semiconductor foundry service confirm the power factor of 0.075 μW/cm2K2 and the voltage factor of 7.004 V/cm2K are 1.7 x and 2.5 x, respectively, of that in TEG with co-planar thermocouples. This performance is the best of all TEGs with polysilicon thermocouples by standard CMOS process.