C_bc Reduction in Si-implanted Subcollector HBTs

M. Sun, P.J. Zampardi, S. Tiku and R. Lee*, Skyworks Solutions, Inc., Newbury Park, CA 91320, USA

R.L. Pierson, M.Y. Chen**, M. –C. Ho***, and S. Fitzsimmons, Rockwell Scientific Company, Thousand Oaks, CA 91360, USA

Email: mike.sun@skyworksinc.com Phone: (805)480-4456

*R. Lee is currently with Vitesse Semiconductor, Camarillo, CA 93012. **M.Y. Chen is currently with HRL Laboratories, LLC, Malibu, CA 90265. ***M.-C. Ho is currently with Northrop Grumman Corporation, Redondo Beach, CA 90278

Abstract

We demonstrate the first small area emitter (1.4 x 3 mm²) N-p-n AlGaAs/GaAs HBT’s fabricated with N⁺- implanted subcollectors in a high volume manufacturing environment. The subcollector region was defined by multiple N⁺ implants of various doses and energies on a semi-insulating GaAs substrate, and the remaining HBT layers were grown by MOCVD. To evaluate the impacts of C_bc reduction, devices with varying subcollector areas were fabricated for comparison. Small signal s- parameter data was measured to extract f_T, f_max and C _bc. By varying the implanted subcollector area, the base-collector capacitance C _bc a was reduced by almost 40% using this manufacturable process. The common emitter current gain of devices fabricated by this implant/epitaxial hybid process is about 50 which is similar to our baseline device, indicating good material quality using this technique.

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