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SEMI's Oasis provides respite from GDSII

Posted: 03 Oct 2002 ?? ?Print Version ?Bookmark and Share

Keywords:Semiconductor Equipment and Materials International? GDSII file format? OpenAccess data model? application programming interface? oasis?

Semiconductor Equipment and Materials International (SEMI) rolled out the Open Artwork System Interchange Standard (Oasis) on Monday (Sep. 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 have 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 is 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 will 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 CEO 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 is the right way to approach the problem long-term," he said. But OpenAccess needs more support for mask-making and manufacturing, and "it is 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.

- Richard Goering

EE Times

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