Effect of Lightly Doped Drain Process on Variability for Static Random-Access Memory

The effect of the lightly doped drain (LDD) implantation process on the variability of six-transistor (6T) static random-access memory (SRAM) cells at a V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</inf> value of 1.2 V was investigated. It is found that the variability of static noise margin in the hold, read, and write states decreased with the increase of LDD implantation dose, indicating that increased LDD dose contributes to improving the variability of SRAM cells.