Thermally Optimized and Electrically Isolated Buffer Layer Study in High Volume HBT Manufacturing

A. Zaman, M. Sun, W. Sun, J. Hu, N. Ebrahimi, V. Ramanathan, P. Zampardi and A. Popalzai,
Skyworks Solutions Inc., 2427 W. Hillcrest Drive Newbury Park, CA  91320 
Email:  Phone: (805) 480-4145

An experimental study has been performed to investigate and to optimize the HBT buffer layer for higher collector isolation resistance in a high volume HBT manufacturing environment.  The device characterization results indicate that the interface states at the substrate-epi interface play a critical role in the degradation of collector isolation resistance and were found to be dependant on the substrate type and the growth condition.  With the introduction of thermally optimized and electrically isolated AlGaAs buffer, no difference was observed in the electrical and thermal performance of the Power Amplifier Modules (PAM) 

Keywords:  Ketgerojunction Bipolar Transistors, Collector isolation, AlGaAs buffer

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