Balancing Electrical and Thermal Device Characteristics – Thru Wafer Vias vs. Backside Thermal Vias

Cristian Cismaru, Hal Banbrook, Hong Shen and Peter J. Zampardi
Skyworks Solutions, Inc., 2427 Hillcrest Drive, Newbury Park, CA 91320
cristian.cismaru@skyworksinc.com, 805.480.4663

Keywords: TWV, Backside Thermal Vias, HBT, thermal performance, RF performance.

Abstract

Device design and process strategies improving the circuit thermal stability by lowering the device junction temperature, while minimizing the device thermal resistance, are examined. We investigate adding thick (up to 4 μm) metal layers on top of the HBT device, moving TWVs closer to the device, and using thermal vias. The results show that most of the thermal resistance improvements are obtained if thick metal is used on top of the device, while the TWV plays a less important role. In addition, this work shows that thermal vias have limited use since they degrade the device RF performance.

Paper 11b.2.pdf