Impact of fin height variations on SRAM yield

We demonstrate that the variation of threshold voltage V
_t
of bulk finFET (BFF) devices due to the fin height variation (FHV) constitutes the major part of the overall device variations. Yet, the inter-die FHV affects SRAM cell variation performance in quantitatively comparable manner to intra-die variations (or mismatch). At the product level, however the impact of that component on array performance is negligible, demonstrating that mismatch remains dominating the overall statistical SRAM response and upper yield limit.