Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences

COLLEGE OF ENGINEERING

UC Berkeley

The Simulation of MOS Integrated Circuits Using SPICE2

Andrei Vladimirescu and Sally Liu

EECS Department
University of California, Berkeley
Technical Report No. UCB/ERL M80/7
1980

http://www.eecs.berkeley.edu/Pubs/TechRpts/1980/ERL-80-7.pdf

This report is addressed to all SPICE2 users involved in the design of MOS (Metal Oxide Semiconductor) IC's (Integrated circuits). The material contained herein serves as an addition to the SPICE2.G User's Guide. The device and model parameters documented refer to the SPICE2.G release versions from the University of California, Berkeley and obsolete the information contained in the "SPICE2 MOS Modeling Handbook" which is valid for the SPICE2.D release versions. The impact of MOS IC's in both analog and digital applications as well as the decreasing dimensions of the single transistors enabled by advances in processing have made it necessary to refine the models and to provide more information about each device as it appears on the circuit layout. Associated with each MOSFET is a drain and source-junction sidewall capacitance (which has a different voltage dependence than the bottom of the diffusion) and a parasitic series resistance. These are unique to a certain geometry. At the model level there are effects which become important as the channel length and width go below 10um. A thorough description of all parameters appearing on the element (device) card and model card is contained in Sec. 2. In SPICE2.G there are three different MOS models available to the user. The Level 1 model is the simple Shichman-Hodges model implemented according to Nagel's "SPICE2: A Computer Program to Simulate Semiconductor Circuits." This first order model has been found necessary for checking out the correctness of hand calculations when understanding or developing new circuits. The Level 2 model is an analytical one-dimensional model which incorporates most of the second-order effects of small-size devices. The Level 3 model is a semi-empirical model described by a set of parameters which are defined by curve-fitting rather than physical background. It is necessary for the circuit designer to know what are the equations governing the behaviour of the MOSFETs and what is the influence of the various model parameters even if hand calculations are almost impossible at this complexity. This insight of the MOS2 and MOS3 model equations is found in Sec. 3 and 4. The accuracy of the model depends heavily on the values of the input parameters. These input parameters should be related to the particular process used at each manufacturing site. The large number of parameters which describe the model require the existence of a parameter extraction system. Sec. 5 provides some detail on how to use some simple preprocessor programs for the evaluation of the SPICE2 input parameters from the measurements taken on test devices. Sec. 6 gives an example of a sample SPICE2 MOS IC input deck stressing the correlation among different model parameters and the importance of modelling various second-order effects for a good agreement with measured performance.


BibTeX citation:

@techreport{Vladimirescu:M80/7,
    Author = {Vladimirescu, Andrei and Liu, Sally},
    Title = {The Simulation of MOS Integrated Circuits Using SPICE2},
    Institution = {EECS Department, University of California, Berkeley},
    Year = {1980},
    URL = {http://www.eecs.berkeley.edu/Pubs/TechRpts/1980/9610.html},
    Number = {UCB/ERL M80/7},
    Abstract = {This report is addressed to all SPICE2 users involved in
the design of MOS (Metal Oxide Semiconductor) IC's (Integrated
circuits).  The material contained herein serves as an addition to
the SPICE2.G User's Guide.

The device and model parameters documented refer to the SPICE2.G
release versions from the University of California, Berkeley and
obsolete the information contained in the "SPICE2 MOS Modeling
Handbook" which is valid for the SPICE2.D release versions.

The impact of MOS IC's in both analog and digital applications
as well as the decreasing dimensions of the single transistors
enabled by advances in processing have made it necessary to refine
the models and to provide more information about each device as
it appears on the circuit layout.  Associated with each MOSFET is
a drain and source-junction sidewall capacitance (which has a
different voltage dependence than the bottom of the diffusion)
and a parasitic series resistance.  These are unique to a certain
geometry.  At the model level there are effects which become important
as the channel length and width go below 10um.  A thorough description
of all parameters appearing on the element (device) card and
model card is contained in Sec. 2.

In SPICE2.G there are three different MOS models available to
the user.  The Level 1 model is the simple Shichman-Hodges model
implemented according to Nagel's "SPICE2: A Computer Program to
Simulate Semiconductor Circuits."  This first order model has been
found necessary for checking out the correctness of hand calculations
when understanding or developing new circuits.  The Level 2 model
is an analytical one-dimensional model which incorporates most of
the second-order effects of small-size devices.  The Level 3 model
is a semi-empirical model described by a set of parameters which
are defined by curve-fitting rather than physical background.  It is
necessary for the circuit designer to know what are the equations
governing the behaviour of the MOSFETs and what is the influence of
the various model parameters even if hand calculations are almost
impossible at this complexity.  This insight of the MOS2 and MOS3
model equations is found in Sec. 3 and 4.

The accuracy of the model depends heavily on the values of the
input parameters.  These input parameters should be related to
the particular process used at each manufacturing site.  The large
number of parameters which describe the model require the existence
of a parameter extraction system.  Sec. 5 provides some detail on how
to use some simple preprocessor programs for the evaluation of the
SPICE2 input parameters from the measurements taken on test devices.

Sec. 6 gives an example of a sample SPICE2 MOS IC input deck
stressing the correlation among different model parameters and the
importance of modelling various second-order effects for a good
agreement with measured performance.}
}

EndNote citation:

%0 Report
%A Vladimirescu, Andrei
%A Liu, Sally
%T The Simulation of MOS Integrated Circuits Using SPICE2
%I EECS Department, University of California, Berkeley
%D 1980
%@ UCB/ERL M80/7
%U http://www.eecs.berkeley.edu/Pubs/TechRpts/1980/9610.html
%F Vladimirescu:M80/7