New Mobility Model Improves SSUPREM3 Electrical Analyses

Prof. A.F.Tasch, (U. of Texas) and Dr. T.L.Crandle (SILVACO)


SSuprem3 Version 5.0 (currently shipping) has been improved by the inclusion of a physically-based surface mobility model from the University of Texas.1,2 The effective mobility model is essential for accurate threshold and conductivity analyses. The model, developed to describe electron effective mobility in MOS inversion layers, accounts explicitly for the effects of surface roughness scattering, screened Coulomb scattering, phonon scattering, and fixed oxide charge at the SiO2-Si interface.

The validity of the model as a function of transverse field, temperature, channel doping, and interface charge has been verified by researchers at the University of Texas who developed the model originally to improve MOS device simulation accuracy. The model shows excellent agreement with experimentally measured effective mobility data from many sources and is now the preferred model for S-Pisces 2B simulation.

The new model was implemented in response to customer concerns about the validity of threshold and conductivity calculations using the simplified models previously available. This model adds to the usefulness of the SSuprem3 threshold calculation and its compatibility with S-Pisces 2B analysis.


Figure 1. SSuprem3 conductivity calculation results using
the default model and the surface scattering model. The new model
corresponds to S-Pisces 2B and shows the roll-off in electron conductivity
with increasing gate voltage that is measured experimentally.



[1] H. Shin, A.F. Tasch, C.M. Maziar, and S.K. Banerjee, IEEE Trans. Elect. Dev., Vol. ED-36, p. 1117, 1989.

[2] H. Shin, G.M. Yeric, A.F. Tasch, and C.M. Maziar Solid State Electronics, Vol. 34, No. 6, p. 545, 1991.