Plasma doping for DRAM with deep trenches and hemispherical grains
AssigneeInfineon Technologies AG
InventorsHelmut Horst Tews, Brian S. Lee, Joachim Hoepfner
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Abstract
A method of doping trench sidewall and hemispherical-grained silicon in deep trench cells to increase surface area and storage capacitance while avoiding deformation of trenches and hemispherical-grained silicon, comprising: a) Etching a deep trench structure by reactive ion etching; b) Forming a LOCOS collar in an upper portion of the trench over a conformal layer of a silicon containing material, the collar leaving a lower portion of the trench exposed; c) Depositing a film of hemispherical-grained silicon (HSG-Si) at sidewalls of the deep trench; d) Plasma doping the hemispherical-grained silicon; and e) Depositing a node dielectric and filling the trench with polysilicon.
Claims7
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 300° C.;
- and
- e) Depositing a node dielectric and filling the trench with polysilicon.
Dependencies are inferred from the claim text.