Differential poly-edge oxidation for stable SRAM cells

摘要

An SRAM cell having improved stability includes pass transistors having gate electrodes which are shaped by oxidation so that the lower edges of the gate electrodes are raised away from the substrate surface. Because the gate electrodes of the load and pull-down transistors are masked during the oxidation process, the gate electrodes of the load and pull-down transistors have the conventional rectangular shape. The modified shape of the gate electrodes of the pass transistors decreases the current flowing through the pass transistors relative to that which flows through the pull-down transistors, reducing the likelihood that data can inadvertently be lost from the SRAM cell.