Книги2 / 1993 P._Lloyd,__C._C._McAndrew,__M._J._McLennan,__S._N
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TECHNOLOGY CAD SYSTEMS |
255 |
Edited by F. Fasching, S. Halama, S. Selberherr - September 1993
Technology CAD at OKI
K. Nishi and J. Ueda
OKI Electric Industry Corporation,
550-1 Higashiasakawa, Hachioji, Tokyo 193, JAPAN
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ABSTRACT |
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In this |
article, the outline of Technology |
CAD at OKI is de- |
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scribed. |
TCAD system at OKI, or UNISAS, is a unified |
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process/device/circuit simulation |
system, |
and offers a user- |
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friendly |
simulation environment |
for OKI's |
process, device and |
circuit engineers. Multi-dimensional process and device simulators, OPU'S and ODESA constitutes the core of UNISAS and can be
used for versatile device structures for |
various purposes. |
Physics-based simulators constitute another |
part of UNISAS, and |
are used mainly for modeling purpose. UNISAS has already been used quite extensively by engineers for actual process and device development and is now an indispensable tool for low-cost, fast TAT VLSI development.
256 |
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K. Nishi et al.: Technology CAD at OKI |
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1.Introduction |
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With the first introduction of |
a |
process simulator, |
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SUPREM[11, to analyze a |
full LSI manufacturing process, the idea |
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to fully describe circuit |
performance |
on |
a computer coupled with |
already-existing device simulators and circuit simulators, or TCAD in a current term, evolved as an effective tool for VLSI development in future. OKI recognized the importance of TCAD at
the |
early |
stage, |
and began |
R&D work from the beginning of 80's. |
The |
first |
target |
was to develop a multilayer process simulator, |
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v-lhich was |
first |
announced |
as early as 81 's at the Electrochemical |
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Society meeting[2]. Then, our efforts were drawn more to develop
general-purpose process/device |
simulators for |
versatile |
devices |
and various analysis purposes. |
The unified |
simulation |
system, |
UNISAS (UNIversal Semiconductor Analysis System), |
was |
developed, |
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first with a 1D process simulator, ASPREM |
and a 2D |
device |
simula- |
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tor ODESA[3], and |
later, with a 2D general-purpose |
process |
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simulator OPUS[4]. |
Recently, ODESA was |
linked |
with |
a |
circuit |
simulator, OCAP, with a table look-up model, and nOH, UNISAS is established as a user-friendly effective tool for coupled multi-
dimensional |
process/device |
simulation |
system |
for general pur- |
poses. |
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While major efforts were made to |
develop |
general-purpose |
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simulators, |
research works |
were oriented toward precise modeling |
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of processes and devices. Several simulators were developed to understand physical phenomena during specific processes or in the devices under operation. These simulators are linked with gener- al-purpose simulators and constitute parts of UNISAS.
Modeling work based on experiments was also done to develop such process models as diffusion, and oxidation, and also carrier mobilities. The models have effectively implemented in OPUS and
ODESA, |
and |
contributed |
to more |
accurate process/device |
simula- |
tions. |
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In this |
paper, we show details of UNISAS system, and de- |
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scribe |
outlines of each |
simulator. |
Finally, some of the |
applica- |
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tions are described. |
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2.UNISAS system
2.1General features
The criteria for developing UNISAS are summarized in Table
1. |
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The |
first criterion is an applicability to versatile de- |
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vices. |
Application-specific simulators like a MOSFET simulator |
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are |
much |
faster |
to develop. |
In a long term, however, we believe |
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that |
to |
maintain many |
simulators each for |
specific |
devices are |
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not |
effective. |
For the |
model |
enhancement, |
we have |
to implement |
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K. Nishi et al.: Technology CAD at OKI |
257 |
Table l:Criteria for UNISAS development
Applicability to versatile devices
Flexibility for future enhancement
Flexibility for various simulation purposes
User-friendliness
Fast turn-around-time
Maintenability of the system
them into each simulator. Also preand post-processing work is much more time-consuming with many simulators.
The second criterion is a flexibility for future model enhancement. This include well-ordered file structures as well as well-ordered module organization and programing itself.
A flexibility for various simulation purposes is also a concern. Some engineers need fast simulations for evaluating only device sensitivity on some process or device parameters, and other engineers may need more precise simulations to understand device operations.
Th~ fourth criterion is a user-friendliness. From the beginning of the system development, we intended UNISAS not only
for research |
purposes |
but also for a practical tool used by |
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actual |
device |
designers. |
Graphics was also one of a major target |
at the |
beginning. |
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USER INPUT
GENERAL
PURPOSE
SINULATORS
SPECIAL
SINULATORS
PHVSICAL
DATABASE
Fig.l:System structure of UNISAS