Patent ID: 6475859
Filing Date: 2002-11-05
Classification: H01L

Abstract:
A method of doping trench sidewall and hemispherical-grained silicon in deep trench cells to increase surface area and storage capacitance while avoiding viscous flux of Si that leads to deformation of trenches and very small hemispherical-grained silicon resulting from high temperature doping, comprising:a) Etching a deep trench structure by reactive ion etching; b) Forming a LOCOS collar in an upper portion of said trench over a conformal layer of a silicon containing material, said collar leaving a lower portion of said trench exposed; c) Depositing a film of hemispherical-grained silicon (HSG-Si) at sidewalls of the deep trench; d) Plasma doping said hemispherical-grained silicon at a temperature of less than 300Â° C.; and e) Depositing a node dielectric and filling the trench with polysilicon.