Modular bipolar analysis

Abstract

As bipolar device structures get more complicated in geometry and processing, a need for a systematic modeling approach is required to enable device, process, and circuit engineers to communicate effectively in optimizing integrated circuit designs. This paper discusses a generalized modular model that can be used to analyze any arbitrary bipolar transistor or device structure from basic process parameters. The device's impurity profiles are converted into electrical parameters (using a closed recursive equation) that can be used with most circuit analysis programs to represent electrically the physical structures being analyzed. The solution of a general module is presented which allows the D. C. and transient analysis of any bipolar device. With this model, optimum processes and geometries can be developed to meet the required circuit performance. The model thus becomes an interactive tool to characterize a proposed process for a specific circuit or device application. The example shown to demonstrate the power of this modeling technique is the characterization of a simple IIL (MTL) gate delay in a ring oscillator configuration. The agreement between the calculated and measured propagation delay is within 10% over the range of injector currents evaluated.