October 1, 2002
SEMI's OASIS provides respite from GDSII
By Richard Goering, EE Times |
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SEMI's OASIS Provides
Respite from GDSII
MONTEREY, Calif. — Semiconductor Equipment
and Materials International (SEMI) rolled out
the Open Artwork System Interchange Standard
(Oasis) on Monday (Sept. 30) as a replacement
for the GDSII file format, and said it promises
a tenfold reduction in design data compared
to GDSII. But Oasis still needs work, SEMI said,
and the organization's long-range vision —
for a universal data model (UDM) that links
design to manufacturing — is still in
its infancy.
Representatives of SEMI's IC design/photomask
data path task force had touted Monday's introduction
of a "new stream format" (NSF) replacement
for GDSII, and said the event would provide
a first look at the UDM concept. UDM is proposed
as a way to use the OpenAccess data model
and application programming interface (API)
to transfer design-intent data to manufacturing
personnel and process-related data to designers.
The benchmarks presented by SEMI on Monday
showed that Oasis generally met its stated
goal of providing at least a tenfold data
reduction compared to GDSII. But SEMI representatives
acknowledged that work remains to be done
in such areas as support for hierarchy and
curvilinear figures.
The Oasis 1.0 proposal still needs to go through
balloting and proceed to the SEMI Worldwide
Microlithography Committee for a vote. But
it could be available for public use as early
as March 2003, and the three largest EDA vendors
— Cadence Design Systems Inc., Synopsys
Inc. and Mentor Graphics Corp. — have
all pledged rapid support, SEMI representatives
said.
A potential clash of standards was averted
Monday when Selete, the Japanese IC industry's
process technology research organization,
announced its support for Oasis. Selete had
previously been working on a GDSII replacement
format of its own.
"A year ago we set out to take on a
billion dollar challenge," said Tom Grebinski,
chairman of SEMI's IC design/photomask data
path task force. "Bit inefficiency costs
$4-to-$6 billion per year, and we've done
something about it."
Kurt Wampler, chairman of the SEMI task force's
NSF working group, said Oasis' goals were
to achieve a tenfold reduction in file size
versus GDSII; efficiently handle flat geometric
data; remove 16-bit and 32-bit restrictions
now in GDSII; enhance the "richness"
of information in the format; and make that
format publicly available.
Varied
Reductions
Wampler provided test cases from Motorola,
Advanced Micro Devices and IBM showing data
reductions in the fivefold to twentyfold range.
On a large set of small test cases that Wampler
ran at ASML MaskTools, where he is a distinguished
engineer, he said he found data reductions
varying from 1.4 times to 121.7 times. A few
of the original goals for Oasis were not met,
such as support for curvilinear features,
Wampler said.
Carl Vickery, senior software development
engineer at Texas Instruments Inc., noted
that most of these examples involved data
before optical proximity correction (OPC)
was performed. TI test cases showed reductions
of only around fivefold for what Vickery called
"unfriendly, flat, post-OPC data."
Thus, Vickery said, post-OPC data compresses
far less than the stated goal of 10 times,
as does fractured data, which he said shows
a two-and-a-half to threefold reduction versus
Mebes format files. "On curvilinear figures,
we shamefully punted," he said.
While Oasis retains the hierarchical support
currently found in GDSII, "there's no
great leap forward," Vickery said.
Lars Ivensen, senior design engineer at Micronic
Laser Systems, said that preserving hierarchy
is "the next big thing to address"
with the design-to-manufacturing data transfer.
EDA vendors should find it easy to support
Oasis, said Leigh Anderson, product marketing
manager at Mentor Graphics. Producing Oasis
readers and writers is a matter of "engineer
weeks, not months," he said, and the
maintenance effort will be a matter of "engineer
days." Mentor will support Oasis with
its Calibre and IC Station tools in the first
half of 2003, Anderson said.
"I think you'll see that EDA companies
will continue to support GDSII for a very
long time, and that the new stream format
Oasis will be supported in a very short period
of time," he said. Mentor provided the
initial version of the format that evolved
into Oasis.
Readers, writers for sale
Steve Schulz, president and chief executive
officer of the Silicon Integration Initiative
(Si2), said Si2 will offer Oasis readers and
writers for the OpenAccess data model in early
2003. These products will be sold, marking
a new business model for the venerable standards
organization, which oversees the OpenAccess
Coalition, an industry group focused on design
tool interoperability.
Schulz didn't say much about the UDM, but
called Si2's Oasis readers and writers "the
first step in a long-term partnership."
Scott Peterson, director of platform tools
and methodology for LSI Logic Corp., and chairman
of the OpenAccess Coalition, described how
OpenAccess could link design with OPC, mask
data preparation and mask writing. "We
may be able to make mask-making much more
efficient, if we can do OPC as we go,"
he said. He also said that an OpenAccess-based
UDM could bring manufacturing data into design,
providing, for example, information about
critical versus non-critical structures and
timing sensitivities.
Discussions on the UDM are not about a monolithic
database, but about a common data model and
API. Grebinski said that individual tools
would have their own tool-specific UDM "tokens"
or APIs. All design and manufacturing data
would then be available through an API layer.
One audience member at the Monday rollout
raised the issue of liability, and asked who
will take responsibility for what. Companies
are even hesitant to give out GDSII files
today, he noted, because of intellectual property
protection concerns.
Michael Sanie, director of marketing at Numerical
Technologies Inc., said that a UDM based on
OpenAccess will solve problems related to
smaller geometries, device complexity, and
the dis-aggregation of the chip manufacturing
process. "It's the right way to approach
the problem long-term," he said. But
OpenAccess needs more support for mask-making
and manufacturing, and "it's still perceived
of as a Cadence thing," Sanie noted.
Although it can serve multiple databases,
the OpenAccess data model and API is based
on Cadence's Genesis database, and thus far,
few of Cadence's direct EDA competitors have
signed on to support the initiative.
Sanie also noted, however, that EDA vendor
support for Oasis is not a done deal. Even
though the three biggest vendors are on board,
Sanie said, there are still 30 to 40 EDA vendors
that use GDSII to transfer data between design
steps. "Will they all replace GDSII with
Oasis, and if so, when?" he asked.
