A 50 ns 4K static DSA MOS RAM

An advanced DSA MOS (DMOS) technology is discussed as it applies to a high-speed 4K bit semiconductor static memory. It uses a polysilicon gate length of 4 /spl mu/m, a gate oxide thickness less than 800 /spl Aring/, and a shallow junction depth (<0.6 /spl mu/m) using conventional photolithographic methods. With these features, the effective channel length of the DSA MOST was reduced to 0.5 /spl mu/m and a smaller junction capacitance was obtained by the use of a high-resistivity (100-200 /spl Omega/.cm) substrate without a substrate bias generator. Combined with the depletion load transistors and selective oxidation processing, a static RAM of 50 ns access time at 630 mW power dissipation, die size of 5.24/spl times/5.36 mm/SUP 2/, and cell size of 53/spl times/62 /spl mu/m/SUP 2/ was obtained.