Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences

COLLEGE OF ENGINEERING

UC Berkeley

   

2008 Research Summary

BSIM for Mixed Mode Circuit Simulation Using Advanced CMOS (BSIM)

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Mohan Vamsi Dunga, Darsen Duane Lu, Chung-Hsun Lin, Tianjiao Zhang, Chenming Hu and Ali Niknejad

The continuous evolution of bulk CMOS technology has fueled the growth of the microelectronics industry for the past several decades. Even as we reach the "end" of the technology roadmap for bulk CMOS, the demand for bulk CMOS is healthy. The BSlM series of compact MOSFET models are industry standards successfully used throughout the semiconductor industry and the research community for digital and analog circuit design. Incorporation of new physical effects, support of new materials and devices, and the ability to handle variation in advanced processes represent a critical semiconductor industry need for designs utilizing bulk CMOS and partially and fully depleted SOI.

Toward this end, the bulk and SOI models are being improved to support devices with High-K dielectric / metal gate stack. Enhanced gate tunneling current model will be able to capture leakage due to the Frenkel-Poole tunneling mechanism. Surface optical phonon scattering has been found to be a possible mobility degradation mechanism in MOSFETs with High-K dielectrics [1]. Investigation is being done to determine whether this new mechanism is crucial for the modeling of I-V in High-K / metal gate MOSFETs.

As minimum device area in advanced technology keeps shrinking, flicker noise (or 1/f noise) in small area devices deviates from its well-known 1/f behavior. Noise not only has a different spectrum, but also varies from device to device. In order to capture this effect, the BSIM flicker noise model is enhanced to predict flicker noise variation, either through Monte Carlo simulation (Figure 1) or by providing a band to describe the statistical variation.

Figure 1
Figure 1: Flicker noise variation in small area device predicted by the model

[1]
R. Chau, S. Datta, M. Doczy, B. Doyle, J. Kavalieros, and M. Metz, "High-K/Metal-Gate Stack and Its MOSFET Characteristics," Electronic Device Letters, Vol. 25, No. 6, June 2004.