On the Performance and Scaling of Symmetric Lateral Bipolar Transistors on SOI

Abstract

The performance potential and scaling characteristics of thin-base SOI symmetric lateral bipolar transistors were examined using 1-D analytic equations for the currents and capacitances. The device can operate at collector current densities >100 mA/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and it scales similarly to CMOS in terms of density. The physical base width is scalable to less than 20 nm. Multiple devices of different specifications can be integrated on a chip. A sample design is shown to have f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> > 200 GHz, f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> >1 THz, V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</sub> > 4V, and a self gain of 60. A balanced design is shown to have 350-GHz <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">fT</i> and 700-GHz <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> , <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VA</i> of 2.4 V, and a self gain of 20. These results are superior to those reported for 32 nm SOI CMOS. The results suggest a need to rethink bipolar circuit design. They also suggest opportunities for novel bipolar and BiCMOS circuits. The devices in high-speed Si-base bipolar circuits operate at about 1.0 V. The path toward 0.5 V bipolar circuits is to use semiconductors with smaller bandgap, such as Ge.