Test structure for universal estimation of MOSFET substrate effects at gigahertz frequencies

Abstract

This paper presents a unit test structure for investigation of bulk effects critical to scalable MOSFET models at gigahertz frequencies. The results are transformed into a generalized representation which may be used in conjunction with existing compact models. The gate-modified test structure is compatible with standard CMOS technology and reveals the dependence of diffusion bias on substrate effects. Several MOSFET layout guidelines are suggested for improved consistency between simulation and actual performance. Measuring examples are provided to illustrate bulk effects as well as the applicability of the method in a practical modeling situation.