Semiconductor device manufacturing: process – Formation of electrically isolated lateral semiconductive... – Recessed oxide by localized oxidation
Patent
1995-03-20
1998-11-17
Fourson, George R.
Semiconductor device manufacturing: process
Formation of electrically isolated lateral semiconductive...
Recessed oxide by localized oxidation
H01L 2176
Patent
active
058375961
ABSTRACT:
A process for forming field oxide on a semiconductor substrate having reduced field oxide thinning comprises forming of an oxide layer over a semiconductor substrate, and forming a protective layer over the oxide layer. A mask is formed over the protective layer thereby forming exposed and covered regions of the protective layer. The exposed portions of the protective layer are removed to form at least first, second, and third disconnected protective structures, wherein the distance between the first and second protective structures is smaller than the distance between the second and third protective structures. The oxide layer and a portion of the substrate between the protective structures is removed to expose a portion of the substrate. A blanket polycrystalline silicon (poly) layer is formed over the substrate, and the poly layer is isotropically etched to remove the poly from between the second and third protective structures and leave a portion of the poly between the first and second structures. The poly between the first and second protective structures is oxidized to form regions of field oxide having a substantially uniform thickness across the substrate. The oxidation between the first and second protective structures can also include substrate oxidation once the poly is consumed.
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