Fully functional 22nm CMOS SRAM cells of 0.099µm² density have been fabricated at IMEC using ASML’s EUV Alpha Demo Tool (ADT). The new cells are 47% smaller than IMEC’s 0.186µm² cell produced at the 32nm node last year. The results were presented during IMEC’s partner review week.
The R&D facility used its high-k/metal-gate FinFET platform for front-end processing, which employed Applied Materials deposition systems, according to IMEC. The FinFETs consist of HfO2 as dielectric and TiN as metal gate and NiPt silicide for the source/drain. The minimum active FIN pitch is 90nm.
"Our successful fabrication of 22nm SRAM cells with EUV is an important milestone, both for the development of 22nm processes, and for the roadmap of EUV lithography,” noted Luc Van den hove, Chief Operating Officer at IMEC. “This SRAM cell integration shows that EUV photo process technology is making excellent progress as a cost-effective single patterning approach. We believe that EUV remains a candidate for use in the later stages of the 22nm technology.”
The FinFET layers were printed using ASML’s 1900i immersion lithography tool. The metallization of the contact holes was realized using Applied Materials most advanced contact processing modules for inter-layer barrier Ti and TiN before tungsten fill and chemical mechanical polishing.
IMEC claimed that the latest results showed good overlay performance with a single patterning approach, suggesting that EUV was a cost effective next-generation lithography technology for volume production applications.