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Shift to 65nm designs likely to be quick

Posted: 12 Apr 2005 ?? ?Print Version ?Bookmark and Share

Keywords:dram? 90nm? power supplies? microprocessors? nand flash?

Many IC designers may quickly move past the 90nm node for digital-dominated designs to 65nm design rules. However, richer models are needed to improve first-time design success rates, said Ted Vucuverich, senior vice president of advanced R&D at Cadence Design Systems Inc.

The 130nm node is likely to have a relatively long life as mixed-signal designers cling to the 1.2 V power supplies needed for analog functions, Vucuverich said here at a Fabless Semiconductor Association seminar. The 1V rating for most 90nm offerings is not attractive for analog-intensive designs, he said.

For digital-dominated designs, graphics companies such at ATI, Nvidia and others are moving quickly to 65nm design rules - in some cases even faster than vendors of high-performance microprocessors, NAND flash and DRAMs.

"Once designers figure out the parasitics and how to deal with power issues, they go to 65-nm quickly," he said.

There are few materials changes from the 90- to 65nm nodes, with high-k, interconnect and inter-metal dielectrics roughly the same. Moreover, the techniques employed at the 90nm node to keep leakage currents under control can be adapted to the 65nm node, he said.

Asked about mask costs, Vucuverich said the industry is working to differentiate between the crtical and non-critical mask features, pointing to research by Mark Mason at Texas Instruments Inc. and Karen Maex at IMEC, the Belgium-based Interuniversity Microelectronics Center. The use of more optical proximity correction at the 65nm node will not slow down most companies, and the 193nm scanners are nearly the same, he added.

Vucuverich said the industry badly needs to shift to richer models that include support for statistical timing, power, and yield predictions. Support for statistical timing is being implemented now at leading integrated device manufacturers for both high-performance and high-volume products, he said.

While IDMs can accomplish the shift by sharing information between design process, modeling and manufacturing engineers, he said foundries sometimes hit a wall created by "the sanctity of information" between the various engineering disciplines.

"We have to move away from static libraries. And extraction, modeling and simulation needs to be a lot more integrated," he said. The use of multithreading will allow parallel-computing techniques to be applied to the more complex design models, he said, adding that many current EDA tools can be readily adapted to statistical timing techniques.

The shift to statistical timing will have the immediate effect of reducing design margins that leave a great deal of performance on the table. "The window can be much narrower, and more aggressive," he said.

The industry has been weighed down by relatively poor first-time design success rates, he said, quoting data from analysis firm Collett and Associates. In 2003, only about one-third of the 130-micron designs achieved first-time success. After the third iteration, only 60 percent of the designs worked, he said, attributing hard-to-detect in the designs for the low rate of improvement. After three failures, many designs afflicted with "really hard problems" are declared disasters and abandoned altogether, he said.

- David Lammers

EE Times

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