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'First' 22nm SRAM cells from EUV litho debut

Posted: 28 Apr 2009 ?? ?Print Version ?Bookmark and Share

Keywords:EUV lithography? extreme ultraviolet? SRAM 22nm?

IMEC has presented what it claims is to be the first functional 22nm CMOS SRAM cells made using extreme UV (EUV) lithography. The SRAM cells are made with FinFETs and have both the contact and metal-1 layer printed using a full-field EUV alpha demo tool (ADT) from ASML.

The ultrasmall circuit structures were made using Applied Material's most advanced deposition systems. These results were presented during IMEC's core partner review week, which was attendeddespite the economical downturnby 250 experts representing IMEC's industrial partners in its CMOS scaling program.

IMEC works with Intel, Micron, Panasonic, Samsung, TSMC, Elpida, Hynix, Powerchip, Infineon, NXP, Qualcomm, Sony and STMicroelectronics

The SRAM cell has an area of 0.099?m?, representing a 47 percent area scaling compared to the 0.186?m? of IMEC's 32nm cell reported last year. For the front-end-of-line process, IMEC used its high-k/metal-gate FinFET platform. The FinFETs consist of hafnium dioxide as dielectric and titanium-nitride as metal gate and nickel-platinum silicide for the source/drain. The minimum active FIN pitch is 90nm. The FinFET layers were printed using ASML's 1900i immersion lithography tools. 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.

Compared to the 32nm cell, where only the contact holes were printed with the EUV tool, IMEC now used ASML's ADT to pattern both the contact with a size of approximately 45nm and metal-1 layers (60nm width and 46nm spaces). The single patterning approach strengthens the case for EUV as a cost-effective lithography solution, according to IMEC.

"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," said Luc Van den Hove, chief operating officer at IMEC, in a statement.

"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."

Van den hove added: "Key to the success of our research is the presence at IMEC of leading tool suppliers allowing us to use the most advanced tools, the collaborative research of our staff and the on-site residents from IDMs, foundries, equipment and material suppliers, and the support and funding of the EC program PULLNANO. With such concerted collaborations, the semiconductor industry is able to keep innovating and to follow Moore's momentum."

- Peter Clarke
EE Times Europe

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