Advanced process for recessed poly buffered locos
AssigneeMicron Semiconductor, Inc.
InventorViju K. Mathews
Life of this patent
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Abstract
A process useful for isolating active areas of semiconductor devices, comprising the steps of: forming pad oxide, polysilicon, and nitride layers superjacent a substrate; patterning and etching the layers and the substrate, thereby forming a recess in the substrate; forming a nitride spacer within the recess, then growing a field oxide region therein; removing the layers thereby causing an indentation to form within the periphery of the field oxide region; disposing polysilicon within the indentation; etching the polysilicon to a level even with the field oxide region; and oxidizing the polysilicon.
Claims20
A method for forming an isolation device comprising the following steps of:
- providing a semiconductor substrate having a surface;
- forming a plurality of layers on the surface of said semiconductor substrate;
- patterning and etching said layers, thereby exposing a portion of said substrate surface;
- etching said exposed portion of said substrate to a level below said surface of said substrate;
- growing a field oxide region on said etched portion of said substrate;
- removing said layers, thereby forming an indentation within said field oxide region;
- and
- substantially eliminating said indentation, wherein said indentation is eliminated by:
- filling said indentation with a conformal film;
- planarizing said conformal film;
- and
- oxidizing said conformal film.
A process useful for isolating active areas of semiconductor devices, comprising the following steps of:
- forming at least a pad oxide layer, a polysilicon layer, and a nitride layer superjacent a substrate;
- patterning and etching said layers and said substrate, thereby forming a recess in said substrate;
- forming a nitride spacer within said recess;
- growing field oxide region in said recess, said field oxide region having a periphery;
- removing said layers, said removal causing an indentation to form within said periphery of said field oxide region;
- disposing polysilicon within said indentation;
- etching said polysilicon to a level essentially planar with said field oxide region;
- and
- oxidizing said polysilicon.
A process for fabricating a recessed field oxide area, comprising the following steps of:
- disposing successive layers of pad oxide/nitride/oxide/polysilicon/nitride on a substrate;
- anisotropically etching said layers and said substrate, thereby forming a recess in said substrate;
- oxidizing the resulting exposed portion of said substrate, thereby forming a field oxide region;
- removing said nitride/oxide/polysilicon/nitride layers, thereby causing irregularities in said field oxide region;
- depositing a polysilicon film superjacent said substrate;
- dry etching said polysilicon film;
- oxidizing said polysilicon film;
- and
- stripping said pad oxide layer.
Dependencies are inferred from the claim text.