At 0.128 µm2, a new SRAM cell using fin-shaped FETs (FinFETs) is the smallest such cell ever developed, according to Toshiba Corp, IBM, and AMD. The companies reported their achievement in a technical paper presented at the International Electron Devices Meeting Dec. 16 in San Francisco, Calif.
The cell, which uses a high-k/metal gate (HKMG) material, is less than half the size of the 0.274 µm2 non-planar-FET cell previously reported. To achieve this result, the team optimized the processes, especially for depositing and removing materials, including HKMG, from the vertical surfaces of the non-planar FinFET structure.
The researchers also investigated the stochastic variation of FinFET properties within the highly scaled SRAM cells and simulated SRAM cell variations at an even smaller cell size. They verified that FinFETs without channel doping improved transistor characteristic variability by more than 28%. In simulations of SRAM cells of 0.063 µm2 area, equivalent to or beyond the cell scaling for the 22-nm node, the results confirmed that the FinFET SRAM cell is expected to offer a significant advantage in stable operation compared to a planar-FET SRAM cell at this generation.