Heterogeneous integration of thermoelectric (TE) thin films on CMOS substrates can enable on-chip power generators and coolers co-fabricated with other microsystems. One of the broad applications is chip-scale cooling for analog electronics, RF-MEMS resonators or infrared imaging sensors, which see a decrease in noise figure at lower temperature. Another application is to harvest energy from uneven heat distribution in ICs and to cool down undesired micro-hotspots, which can lead to 5-30°C temperature variation across the same chip. Previous studies on heterogeneous TE integration on CMOS have been limited to conventional materials (poly-Si/SiGe), which have very low thermoelectric figure of merit. In this study, we demonstrated the integration of Bi2Te3 and Sb2Te3 thin films on a CMOS substrate for the first-time. These TE films were considered as non-CMOS compatible prior to this research. The materials are deposited by co-evaporation with improved contact resistance via pre-deposition surface treatments, and the measured transistor performance showed no significant change. A thermoelectric harvester (4 mm2) is fabricated on the CMOS substrate, and generated 0.4 μW from ΔT=20 K.
E. E. Aktakka, N. Ghafouri, C. E. Smith, R. L. Peterson, M. M. Hussain, K. Najafi, “Post CMOS FinFET integration of bismuth telluride and antimony telluride thin film based thermoelectric devices on SOI substrate,” IEEE Electron Device Letters, vol. 34, pp. 1334-1336, 2013.
E. E. Aktakka, C. E. Smith, N. Ghafouri, R. L. Peterson, M. M. Hussain, K. Najafi, “Heterogeneous integration of co-evaporated bismuth/antimony telluride thin films based thermoelectric harvesters on FinFET CMOS chip” 12th Int. Conf. on Micro and Nanotechnology for Power Generation and Energy Conversion Apps. (PowerMEMS’12), Atlanta, USA, pp. 97-100, Dec. 2012.