A Study of Wiggling AA modeling and Its Impact on the Device Performance in Advanced DRAM

Abstract

In this paper, a wiggling active area (fin) in an advanced 1x DRAM process was analyzed and modeled using the pattern-dependent etch simulation capabilities of the SEMulator3D® semiconductor modeling software. Nonuniformity in sidewall passivation caused by hard mask pattern density loading was identified as the root cause of the wiggling profile. The calibrated model mimicked these phenomena, giving nearly the same output AA shape as the real fabrication process. The wiggling profile’s impact on device performance was assessed using the built-in drift-diffusion solver of SEMulator3D. Our analysis confirmed that the wiggling profile, induced by micro-loading during a pattern-dependent etch, has a large impact on overall electrical performance in the device. This was especially apparent with the off-state leakage, primarily due to a worse drain-induced barrier lowering effect in a fatter fin.