High Performance Lateral Schottky Collector Bipolar Transistors on SOI for VLSI Applications

Advanced bipolar transistors play a vital role in RF/Microwave applications. But they need to satisfy stringent demands on device performance parameters such as β, gm, and fT. Many of the bipolar technologies developed to meet these demands are vertical structures and suffer from many non−ideal effects at high collector current densities. In the present work, to enhance the performance limits of bipolar transistors, we have proposed three types of lateral Schottky collector transistors in Silicon−On−Insulator (SOI) technology namely, 1) Lateral PNM Schottky Collector BJT, 2) SiGe base lateral PNM Schottky collector HBT and 3) SiC−emitter lateral NPM Schottky collector transistor. To study the novel characteristics of these lateral Schottky collector bipolar transistors, we have used a state−of−the−art two dimensional simulator. The collector base junction of the proposed lateral PNM (NPM) transistor consists of a Schottky junction between N−base (P−base) and metal (M). The device parameters are chosen based on experimental results for the lateral bipolar transistors. The simulated characteristics of the proposed lateral Schottky collector transistors are compared with their equivalent SOI lateral PNP (NPN) transistors. It is demonstrated that the proposed structures have superior performance in terms of reduced collector resistance, high current gain, suppressed base widening and negligible reverse recovery time compared to the compatible lateral PNP (NPN) transistors in SOI. A simple fabrication procedure is also suggested providing the incentive for experimental verification. Our simulation results suggest that the proposed structures are expected to be very useful in many of the VLSI circuit design applications such as RF/Microwave circuits, low−voltage circuits, and high current driving switches because of their improved performance and compatibility with the BiCMOS technology.