Sram Device Threshold Voltage Mismatch Investigation and Improvement

In this paper, we have found the correlation between SRAM VtMM (threshold voltage mismatch) and key structure parameter include gate CD and NWFM THK (n work function metal thickness). In addition, we found SRAM VtMM have obvious improvement based on thick bottom TiN and shallow source/drain implant process. We separate DIBL (drain induced barrier lowing) and random doping effect on VtMM and find VtMM have strong correlation with DIBL.