R. E. Stallcup, Z. Cross, Zyvex Corporation, Richardson, TX; W. James, P. Ngo, Microtech Analytical Labs LP, Plano, TX

Summary: In this paper we report, for the first time, a technique for measuring the static noise margin (SNM) of in die 6T SRAM bit cells using an SEM based nanoprobing system. The SNM of a bit cell quantifies the amount of electrical noise that is required, at the cell’s internal nodes, to flip the cell’s contents. [1,2] This information is vital to the engineering cycle to produce faster and more efficient SRAM designs. With the aid of SEM based nanoprobing systems that are equipped with 8 or more probes, measurements such as SNM and bit cell stability are now possible on in-die SRAM transistors.