A main
theme of the work done in the microchip simulation laboratory
is to use simulation of physical processes to aid in improving
the design and manufacturability of microelectronic related
products. A key motivating factor here is that experimentation
is generally very expensive. Consequently, if simulation exists
that is sufficiently accurate, fast, and easy to use, then
it can save considerable expense for developing technologies,
improving existing ones, and making current technologies more
manufacturable. The research in this lab focuses on several
fronts, namely, to obtain the best physical description of
the physical processes involved in the technology, to develop
algorithms that are numerically accurate, robust, and fast,
and to combine these aspects, with appropriate tradeoffs,
into simulation packages that aid in the overall process of
microelectronic technology development and manufacturability.
Much of the current research of this lab focuses on microlithography,
but other work has also begun here on nanoelectronics, and
even into more fundamental aspects involving the interaction
and description of carrier transport and electromagnetic fields.
One
unifying aspect of our work is the belief that "simulation"
is our best means for making predictions about future possible
experiments. Here we mean "simulation" in a very
global sense, and not "simulation" as pertains
to some specific academic or commercial program that a technologist
may or may not have found reliable. Simulation, in the broad
sense, is an encoding of available information about some
phenomena, and the structuring of it in such a way as to
enable the best available replication, interpolation, or
extrapolation of the observed phenomena under similar or
different conditions. This "encoding of available information,"
means our best encapsulation of experimental measurements
and theoretical knowledge, combined. If there is some new
aspect of the phenomena that has been discovered, then what
better way to record that knowledge than to fold it into
the knowledge base and logic incorporated into a "simulation
tool?" If a particular simulation tool is not "reliable,"
then either the phenomena is not well understood
or characterized to begin with, perhaps over the regime
of data in question, or the implementation of the available
knowledge about the experiment has not been adequately carried
out. Regarding the latter, we note that poor implementation
can cover a wide range of categories, from very simple,
basic coding mistakes, to user-friendly issues, to the very
difficult problems of numerical robustness, stability, and
convergence.
Our
emphasis on simulation here should not be perceived as meaning
we believe simulation is some sort of magical panacea. Of
course, continued experimentation in new areas is absolutely
essential. The right balance between simulation and experimentation
is a difficult question to answer, and depends on many factors,
such as the sophistication of the simulation program with
respect to the phenomena being examined, the skill in using
the program, the experimental factors that can be controlled,
the skill and expertise of the experimenter, the availability
of equipment, the relative expenses of the two approaches,
etc. In general, both simulation and experimentation help
each other test, confront, confirm, and probe each other's
predictions and results. Often one or the other will produce
results that are puzzling and in the end turn out to be
mistakes in procedures; continued checks help to ensure
that long periods of time are not spent on wrong directions.
Some experimental results are absolutely critical for providing
calibration or model parameters to a simulator. Some simulation
results yield intermediate physical results that are nearly
impossible to obtain experimentally, but that yield enormous
physical insight into the inner workings of the mechanisms
involved in the phenomena.
Nevertheless,
having made this point on experimentation, we again emphasize,
that the use of simulation, in the most general sense, does
indeed appear to be our best means available for encoding
available information, obtained by whatever means, and using
that information to make predictions on physical processes
and experiments. Moreover, by making the simulation tools
as user friendly as possible, then enormous gains can be
obtained for designing and improving present and future
technologies. Indeed, one may even argue that if these goals
of an adequate simulator have been realized, then not using
simulation tools results in inefficient business practices
and a severe handicap as compared with competing technologists
who make solid and effective use of simulation methods.
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