Study and Improvement on Floating Gate CMP Process in Embedded Flash Memory
Qiyu Huang · Electronics & Packaging · 2011
With the development of CMP technology and the shrinking of flash memory critical dimensions,more requirements are imposed on poly surface performance and the overlay between different photo layers.CMP technology is also used for floating gate poly planarization.There will have big impacts on device electric parameters and the following processes if floating gate poly thickness uniformity and poly surface quality are not good.Therefore,how to get a stable,uniform and good surface quality poly gate is very important for mass production.In this dissertation,poly residue and dishing issue have been studied during developing 90nm embedded flash FG(Floating Gate)CMP process.Getting much improvement by the experiments to reduce STI(Shallow Trench Isolation)HDP(High Density Plasma)dishing and improve the poly thickness uniformity on different AA(Active Area)pattern.