VLSI 2008 Symposium Highlights
(06/17/2008 4:00 PM EDT)
MANHASSET, N.Y. — The interdependence between process and design is
in full evidence at this year's VLSI Symposia, being held June 17-20
in Honolulu, Hawaii. The Symposium on VLSI Technology straddles the
Symposium on VLSI Circuits. This year the conference has two overlap
days to provide a combined forum that addresses issues from
processes, devices and circuits to system-level design and
A few papers testify to this increasing interdependence.
In three papers, experts from the Sematech semiconductor consortium
detailed new techniques for extending CMOS logic andccepts and
describing how current semiconductor technologies can benefit from
performance-enhancing features for future scaling needs.
"Our goal is to provide innovative and practical solutions for
continued scaling of semiconductor technologies that can easily be
incorporated in real-world manufacturing environments," said Raj
Jammy, Sematech vice president of emerging technology.
The papers discussed leading-edge research into areas such as
high-k/metal gate (HKMG) materials, and planar and nonplanar CMOS
technologies. Specifically, the experts revealed a method to enable
sub-1-nm EOT (equivalent oxide thickness) demonstrating scaling of
SiGe PFETs at 22-nm nodes.
Meanwhile, IBM researchers revealed a prototype 45-nm six-transistor
L1 and L2 cache SRAM chip set capable of reaching SRAM cell speeds
beyond 6.5 GHz. This is an improvement on IBM's presentation last
year at the VLSI conference held in Kyoto, where an 8-T device was
detailed operating at 6 Ghz.
"The research results show that it is possible to achieve high
performance for a 6-T [six-transistor] device while maintaining full
functionality using several new features that enable improved
writeability, stability and read/write margin analysis capability,
as well as means to accurately measure internal cell speed compared
to previous 6-T designs," said Rajiv Joshi, research staff member at
IBM's T. J. Watson Research Center.
In addition, a newly developed super-fast Monte Carlo-based
statistical analysis was used to design SRAM circuit blocks as well
as arrays. The algorithms and methods employed improve Monte Carlo
analysis by several orders of magnitude for such complex circuit
blocks. The technique was successfully employed in predicting SRAM
Fujitsu Labs and Fujitsu Microelectronics Ltd. discussed recently
developed circuit technology that can rapidly switch a power supply
from off to on in less than 1 microsecond. This makes it possible to
extend the "off" period, or sleep time, of a chip as a means to
reduce leakage current, enabling highly integrated chips to consume
Fujitsu tested the technology on a dual-core processor with 2
million gates fabbed in 90-nm process technology. The resulting
restoration time was 240 nanoseconds and power-supply noise was 2.5
millivolts, compared with 20 millivolts for existing technologies, a
reduction of 87.5 percent, according to the Fujitsu researchers.
Also presented was a paper on a microchip developed at the
University of Michigan that uses 30,000 times less power in sleep
mode and 10 times less power in active mode than comparable chips
now on the market.
The Phoenix processor is geared toward sensor-based devices such as
medical implants, environment monitors and surveillance equipment.
The chip consumes just 30 picowatts during sleep mode. Sizewise,
Phoenix is the same dimensions as its thin-film battery, which is a
A group of U-M researchers is installing the Phoenix in a biomedical
sensor to monitor eye pressure in glaucoma patients. Engineers
envision that chips like this could also be sprinkled around to make
a nearly invisible sensor network to monitor air or water or to
The device defaults to sleep mode: "Sleep-mode power dominates in
sensors, so we designed this device from the ground up with an
efficient sleep mode as the No. 1 goal. That's not been done
before," said Dennis Sylvester, an associate professor in U-M's
Department of Electrical Engineering and Computer Science.
Phoenix runs at 0.5 volt.