Virtual technology for RF process and device development

Abstract

The increasing complexity of modern technologies has made semiconductor process and device development challenging. A reduction in the number of experimental tests and a detailed internal insight opens the way to a more optimized process in a shorter time at reduced costs and development time. This has largely increased the use of virtual technology platforms for technology development and circuit optimization in e.g. RF BiCMOS applications. The capability of accurate predictions and directly linking basic technology parameters to RF circuit performance makes virtual technology a very powerful tool during RF process and device development. Commercially available technology computer-aided design (TCAD) tools are generally used during device fabrication and characterization, process optimization, and circuit design. With three examples we illustrate the evolution of the virtual technology process used for RF BiCMOS development within NXPSemiconductors. In the first two examples, we illustrate device and process optimization while in the third example we describe a new way of combining device and process optimization with circuit simulations by means of a distributed equivalent circuit. It allows to take the interaction between the intrinsic device (i.e. device doping profile) and the parasitic environment (i.e. device architecture) efficiently into account for high-frequency applications and in particular for low-noise circuits.

Lumped Models for Assessment and Optimization of Bipolar Device RF Noise Performance

“…Even though this is consistent with the small-signal model of the intrinsic transistor, such model ceases to be valid at higher frequencies [10], [11]. An improved version of this method [12] replaced the intrinsic small-signal circuit by a 1-D Technology Computer Aided Design device simulation. Nevertheless, still a simplified uncorrelated noise model for the intrinsic transistor was used, inconsistent with the smallsignal model of the intrinsic transistor.…”