Impact of emitter interface treatment on the horizontal current bipolar transistor (HCBT) characteristics and RF circuit performance

Abstract

The impact of the HF cleaning step prior to the emitter α-Si deposition on the Horizontal Current Bipolar Transistor (HCBT) electrical characteristics is analyzed A longer HF dip results in a thinner emitter interface oxide implying a smaller emitter resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</sub> ), which equals 85Ω for the unit HCBT as compared to 104 Ω for the unit HCBT with a shorter HF dip. The thinner oxide is still sufficiently thick to block the emitter α-Si etching and protect the intrinsic transistor structure. The impact of the emitter interface properties on the performance of designed high-linearity double-balanced active mixers is examined. The reduction of the emitter resistance results in 1.8 dB higher conversion gain and 2.4 dB lower IIP3 at 50 mA for the mixer without degeneration emitter resistor (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</sub> ). The effect of interface oxide thickness is shown to be negligible for R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</sub> >10 Ω. The HCBT mixers achieve maximum IIP3 of 23.8 dBm and conversion gain of 2.4 dB at the current of 50 mA.