Challenges of High Aspect Ratio Oxide Etching

摘要

Oxide etch processes needed for future DRAM technologies become increasingly challenging due to the high aspect ratios required. Based on an extensive series of experiments we investigate the influence of aspect ratio on both, etch rates and profile control. Contact hole distortions such as profile bowing, increased ellipticity, misshaped cross-sections and their dependences on various etch parameters are discussed. The understanding of these phenomenon allowed us to successfully develop plasma etch processes for fabrication of contact holes in SiO_2 with aspect ratios of 20:1 and beyond.