Toshiba has developed a cost-effective 32nm CMOS platform technology that offers higher density and improved performance while halving the cost per function from 45nm technology.
The platform was achieved by application of advanced single exposure lithography and gate-first metal gate/high-K process technology. This technology enables a 0.124μm2 SRAM cell and a gate density of 3,650 gate/mm2. This SRAM cell is the smallest yet achieved in the 32nm generation. The platform technology is based on a 32nm process technology developed jointly with NEC Electronics.
Advanced semiconductor process migration faces challenges to achieve both cost competitiveness and enhanced performance for stricter design rules. This requires technological optimization in lithography and patterning integration, materials, and device design.
Realizing the strict design rule in the 32nm generation was originally seen as requiring dual exposure technology in the lithography process, which would result in higher process costs due to increased process steps, and in degraded manufacturing yields owing to increased process dusts. Toshiba realized an architecture based on single exposure lithography by applying ArF immersion lithography with a NA 1.3 and over, and by optimizing the lithography illumination conditions.
The development work also demonstrated that application of a metal gate/high-K not only boosts transistor performance but also reduces threshold voltage mismatch, which affects stable operation of SRAM and logic circuits. In addition, a bent-shaped type cell was selected for layout optimization, which also contributed to reduce threshold voltage mismatch.
By adopting this approach, Toshiba realized a 32nm CMOS platform design that reduces cost per function by 50% from 45nm technology, an achievement that would have been impossible with conventional poly/SiON and double patterning.
Toshiba said that it would further enhance development of the new platform.
The achievement was introduced today at the International Electron Devices meeting (IEDM) in San Francisco, CA.
New Platform Technology for 40nm CMOS Process
At the same event, Toshiba announced a 40nm CMOS platform technology based on 45nm process technology co-developed with NEC Electronics. The new platform fabricates SOC for power-critical mobile applications that consume less than half the power of 65nm generation LSI. The company also announced that it expects to deploy the technology on samples in the fourth quarter of FY2008, and in mass production in the second quarter, FY2009.
Advanced mobile application requires reduced chip size and lower power consumption. Process migration is a solution to meet the demand, however, shorter channel length tends to cause current leakage. Both reduction of power consumption and chip size shrinkage require controlling channel impurity concentration and fining layout.
Toshiba has established and applied new platform technology for a new activation sequence using flash lamp anneal, optimizing impurities in the ion implantation process, and applying Hafnium incorporated insulators and DFM (design for manufacturing) technologies. Doubling the flash lamp anneal process boosted both the PMOS and NMOS performance. Doping germanium with nitrogen in the ion implantation process minimized concentration in the channel area, which contributes to higher transistor performance. Hafnium incorporated insulators improve drive current by increasing threshold voltage without excess concentration of channel impurities. Application of DFM technologies enabled aggressively scaled layout with lower lithographic defects.