Pushing SRAM densities beyond 0.13 um technology in year 2000

For any given technology in the logic foundry business it is highly desirable to offer a dense SRAM design which can be manufactured using the same mask and wafer toolsets as the base design. This paper discusses the lithographic issues related to imaging a pseudo-0.11 um technology within a 0.13 um ground rule, including optical proximity correction, design, mask making issues, and comparison of top-down SEM to simulation. To achieve a dense SRAM and quick turn around on design shrinks, simulation and experimental feedback are key. In this study, SRAM cells were redesigned, and a well calibrated resist and etch bias model, in conjunction with a fast micro lithographic aerial image simulator and mask model, were used to predict and optimize the printed shapes through all critical levels. One of the key issues is the ability to correlate and feedback experimental data into the resist simulation. Experimental results using attenuated phase shift masks and state-of-the-art resist process technology are compared to the simulation.