The Compact Model Council FAQ List
The following is a summary of the most frequently
asked questions concerning the CMC and its role in the compact modeling
community. If you have further questions concerning the CMC, please
contact Joe Watts, Chairman of the
CMC.
- What is the Compact Model Council?
The CMC is a group of Semiconductor Vendor companies and EDA Vendor
companies that promote standardization of compact model formulations.
- How does the CMC choose compact models for standardization?
The CMC chooses candidates for compact model standardization based
upon the business needs of its member companies. Candidates are reviewed
by the CMC member companies for accuracy (both qualitative and quantitative)
and deficiencies are identified. Once a candidate is chosen, the CMC will
fund the productization of the model including any CMC specific changes
required.
- Why was the CMC formed?
The CMC was formed to address the gap between compact model research and
compact model usage. This is called productization. Compact modeling research
was well funded, however, it was very rare that the research actually became
a product that the industry could use to address its current needs. The CMC
addressed this need by funding the productization of standard compact models.
The CMC chooses a candidate to be standardized, funds the productization effort,
and directs the changes necessary for the compact model to be used industry-wide.
- What kinds of compact models does the CMC standardize?
The CMC standardizes any compact model formulation that meets the
business needs of its member companies. Currently, there is an effort
in MOS, Bipolar, and SOI technology processes. The MOS technology was
chosen first as it had the highest impact for the member companies.
- Does the CMC pay for research?
No. The CMC pays for the productization of completed research. The
CMC has been asked for its input concerning the direction of the
research, however, the CMC has not funded any research. The main purpose
of the CMC funding is to make a compact model useable across the industry.
- Does the CMC only fund UC Berkeley for the BSIM project?
Currently, the CMC funds only the candidates chosen for standardization.
The BSIM3 model and BSIMPD model have both been chosen for standardization
by the CMC and are currently being funded. Since no choice has been made
for the Bipolar task, no funding has been approved by the CMC for Bipolar
standardization.
- Why are the dues for the CMC so high? Other standards organizations
do not charge so much for membership.
The CMC identified the lack of productization funding as the key problem
with compact modeling. The dues were established to pay for the normal
operating costs of the CMC and for an additional amount to use for funding
productization. The CMC dues are set based upon the number of tasks and
work required to produce standard compact models as well as to make sure
that those models are useable across the industry. Without the additional
funding, standard compact models would not be as attractive to the industry.
BSIM related questions
- Is there a way to determine which version of BSIM3 to use?
The CMC recommends that the latest released version of BSIM3 should
be used. However, the CMC does understand the issues involved with
changing a model during the design cycle. The CMC recommends that
the model user determine what features of the process are critical
to their design and then make sure that they are represented in the
version of model chosen. For the latest release information and descriptions
of the current features of BSIM models, please consult the
UCB Webpage.
- How does the CMC choose which physical effects are necessary in the model?
The CMC chooses physical effects that impact the business needs of its
membership. A good example is the latest changes to the BSIM4 capacitance
model. CMC members expressed a need for better modeling in a certain region
of operation and showed the data to the UCB BSIM team. The BSIM team
came up with a simple solution to the problem and began implementation
into the model code. The CMC members were then asked to verify the solution
to make sure it was acceptable. If new physical effects are encountered
during the research phase, the CMC members will normally be aware of these
issues and determine the impact on their business needs. The CMC does not
fund research to find these new effects, but tries to ensure that they can
be comprehended in the compact model.
- Which version of BSIM3 is the standard model?
This is the most popular question to ask. The CMC approves changes to
the standard model based upon the changes requested by its membership.
BSIM3v3.0 was the first model agreed upon to be a standard. Any revisions
to BSIM3v3.0 were approved by the CMC before UCB released the new version.
CMC members test the changes made and help direct UCB to solving these
problems, such as bug fixes, convergence issues, implementation issues,
and parameter bounding. The current version of the BSIM3v3 model is
considered the standard MOSFET model by the CMC. There is considerable
advantage in being a CMC member in that your concerns can then be addressed
by all CMC members, solutions can be proposed and adopted that address
your company's specific needs.
- When will the next version of BSIM be available in commercial simulators?
The CMC approves releases from UC Berkeley that incorporate the requested changes
by the CMC and included bug fixes from a number of sources. The CMC does not try
to dictate when vendors will release a particular version of BSIM. The best source
for information on BSIM availability in your preferred simulator is to contact your
simulator vendor directly. The CMC does have software vendors as members, so changes
made by the CMC are recognized by the software vendors. The CMC member software
vendors update the CMC on upcoming standard model releases at each quarterly meeting.
This information is usually captured in the minutes of the meetings.
- How are the new standard models tested and with what technologies?
The CMC spent a few years developing a set of tests to run on standard compact
models (MOS and Bipolar so far). These tests are used as a baseline to assess
model accuracy and capability. The MOSFET tests are located on the CMC Website
under the CMOS standardization effort.
Since the CMC does not own any technologies to
test the models, the CMC asks member companies to provide data for testing of the
models or to test the models and report back to the CMC. In most cases, the changes
requested to the standard compact models are a direct result of the testing done by
the CMC member companies.