Method of selectively etching HSG layer in deep trench capacitor fabrication

摘要

The invention provides a method of selectively etching a Hemispherical Silicon Grain (HSG) layer during deep trench capacitor fabrication. A substrate having a pad structure and a deep trench is provided. A buried oxide layer is formed on the upper sidewall of the deep trench and a HSG layer and an ASG layer are formed in the deep trench sequentially. A mask layer is filled into the deep trench and recessed; the exposed ASG layer is then removed. The HSG layer is doped to form a plasma doping layer on the upper portion of the deep trench, which is removed without damaging the silicon substrate. After the mask layer is removed, a cap oxide layer is formed on the deep trench, and the substrate is subjected to a thermal treatment to form a buried plate.