During IMEC’s core partner review week, IMEC showcased the first functional 22nm CMOS SRAM cells made using EUV lithography. The 0.099µm² SRAM cells are made with FinFETs and have both the contact and metal1 layer printed using ASML’s full field extreme ultraviolet (EUV) Alpha Demo Tool (ADT). The ultra-small circuit structures were made using Applied Material’s most advanced deposition systems.
The density of the new record-breaking cells is 0.099µm², representing a 47% area scaling compared to the 0.186µm² 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 HfO2 as dielectric and TiN as metal gate and NiPt 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 ~45nm and metal1 layers (60nm width and 46nm spaces). The results show a good overlay performance. And the single patterning approach further strengthens the case for EUV as a cost-effective solution.
More info: IMEC