NEC Electronics and NEC today introduced a new device technology that delivers both low standby power consumption and high operating speeds for system LSIs using design rules for 55 nanometer (nm) and below. The main features of the new technology are 1) threshold control in the high-k (high dielectric constant) material used as the transistor gate insulator, 2) high carrier mobility through process-induced stress, and 3) a fine-pitch design rule through leading-edge immersion lithography. Together, these advances enabled the development of a 55nm generation CMOS platform.
Thanks to high-k process innovations, this CMOS platform combines a wide threshold voltage range with high carrier mobility, allowing it to provide the low standby power consumption required by mobile devices together with the high performance required by high-speed logic applications, all with the same transistor structure.
To implement 55nm node design rules, the companies used a pioneering immersion lithography process. This allowed the pitch of the M1 interconnect layer to be reduced to 160nm and enabled a SRAM cell size of 0.432 square microns. Compared to widely used 90nm processes, transistor density is 2.5 times higher.
UltimateLowPower(TM), which is a combination of the new device technology and circuit technologies such as variable-voltage power supply, will enable up to a tenfold increase in battery life.
The principal features of the new technology are as follows.
(1) A high-k dielectric for transistor threshold control
Traditionally, the main objective of designs using high-k gate insulators has been to reduce gate leakage, which reduces standby power consumption. However, low gate leakage is difficult to achieve at the same time as low threshold voltage, which is advantageous for high performance. As a result, such designs have had a limited range of application. This problem was overcome by process innovations for the high-k gate layer, which made it possible to widen the threshold voltage range without increasing channel impurities. This result is higher carrier mobility and higher performance.
(2) Higher mobility through process-induced stress
Cost-effective process-induced stress techniques were used to enhance electron and hole mobility. By optimizing shallow trench isolation (STI) stress, sidewall stress, and silicon nitride (SiN) stress on the gate, it was possible to improve the performance of both NMOS and PMOS. Combined with the innovations described in (1), which improve mobility by suppressing impurity scattering, these techniques allowed drive currents to be increased by 22% for NMOS and 31% for PMOS, compared to 65nm nodes from NEC Electronics. These are the highest levels ever attained in the industry.
(3) Fine-pitch design rules through immersion lithography
NEC Electronics pioneered the introduction of argon fluoride (ArF) immersion lithography. This enabled the development of ultra-small SRAM cells with generous operating margins.
NEC Electronics will use this technology to implement low-power/high-performance system LSIs for a wide range of applications, from mobile devices through networking.
NEC Electronics and NEC will announce these results at the 2006 Symposium on VLSI Technology, to be held in Hawaii from June 13 through 15.
About NEC Corporation
NEC Corporation (TSE: 6701; NASDAQ: NIPNY) is one of the world’s leading providers of Internet, broadband network and enterprise business solutions dedicated to meeting the specialized needs of its diverse and global base of customers. NEC delivers tailored solutions in the key fields of computer, networking and electron devices, by integrating its technical strengths in IT and Networks, and by providing advanced semiconductor solutions through NEC Electronics Corporation. The NEC Group employs more than 140,000 people worldwide and had net sales of 4,855 billion yen (approx. $45.4 billion) in the fiscal year ended March 2005.
About NEC Electronics
NEC Electronics Corporation (TSE: 6723) specializes in semiconductor products encompassing advanced technology solutions for the high-end computing and broadband networking markets, system solutions for the mobile handsets, PC peripherals, automotive and digital consumer markets, and multi-market solutions for a wide range of customer applications. NEC Electronics Corporation has 26 subsidiaries worldwide including NEC Electronics America, Inc. and NEC Electronics (Europe) GmbH.