Patent ID: 6440792
Filing Date: 2002-08-27
Classification: H01L

Abstract:
A method for fabricating bottle-shaped deep trench capacitors comprising the steps of:(a) using a photolithography process to form a deep trench into a semiconductive substrate; (b) partially filling said deep trench with a first dielectric material to form a first dielectric layer having a first predetermined depth; (c) forming a sidewall spacer in said deep trench above said dielectric layer, said sidewall spacer being made from a second dielectric material having a different etchability from said first dielectric material and allowing low diffusion rate for ions; (d) removing said first dielectric layer, leaving said portion of said substrate below said sidewall spacer to be exposed; (e) using said sidewall spacer as a mask, causing said exposed portion of said substrate in said deep trench to be oxidized, then removing said oxidized substrate; (f) forming an ion-doped conformal layer around sidewalls of said deep trench, including said sidewall spacer; (g) heating said substrate to cause said doping ions to diffuse into said substrate to form a diffused region in said deep trench not covered by said sidewall spacer, wherein said diffused region becomes said first conductive plate; (h) removing the entire ion-doped layer; (i) forming a conformal second dielectric layer covering a surface of said deep trench including said sidewall spacer, then filling said deep trench with a first conductive material to a second predetermined depth which is above said first predetermined depth; (j) removing said sidewall spacer and said second dielectric layer above said second predetermined depth; and (k) filling said deep trench with a second conductive material, wherein said first and second conductive materials collectively form a second conductive plate.