Semiconductor device manufacturing: process – Formation of electrically isolated lateral semiconductive... – Grooved and refilled with deposited dielectric material
Reexamination Certificate
2000-01-17
2001-02-27
Pham, Long (Department: 2823)
Semiconductor device manufacturing: process
Formation of electrically isolated lateral semiconductive...
Grooved and refilled with deposited dielectric material
C438S692000, C438S738000, C438S743000
Reexamination Certificate
active
06194286
ABSTRACT:
TECHNICAL FIELD
This invention relates to semiconductor processing methods, including, for example, methods of preparing a silicon wafer for fabrication of integrated circuitry.
BACKGROUND OF THE INVENTION
Integrated circuitry is typically fabricated on and within semiconductor substrates, such a bulk monocrystalline silicon wafers. In the context of this document, the term “semiconductive substrate” is defined to mean any construction comprising semiconductive material, including, but not limited to, bulk semiconductive materials such as a semiconductive wafer (either alone or in assemblies comprising other materials thereon), and semiconductive material layers (either alone or in assemblies comprising other materials). The term “substrate” refers to any supporting structure, including, but not limited to, the semiconductive substrates described above.
Electrical components fabricated on substrates, and particularly bulk semiconductor wafers, are isolated from adjacent devices by insulating materials, such as insulating oxides. One isolation technique uses shallow trench isolation, whereby trenches are cut into a substrate and are subsequently filled with insulating oxide, such as undoped silicon dioxide deposited by plasma-enhanced decomposition of tetraethylorthosilicate (PETEOS). In the context of this document, “substantially undoped” means a layer having a dopant concentration which is less than or equal to 10
18
atoms/cm
3
. The insulating material is typically planarized back to define isolated trenches filled with oxide. Subsequently, a previously formed pad oxide layer is removed from over the substrate to expose silicon for processing. Unfortunately, removal of the pad oxide also etches the TEOS deposited oxide and can undesirably form “keyholes” in the shallow trench isolation oxide.
Although the invention spawned primarily out of these concerns, the artisan will appreciate applicability of the following invention in other areas of semiconductor processing.
SUMMARY OF INVENTION
The invention comprises processing deposited oxide and grown oxide materials. In one implementation, a substrate is provided to have outwardly exposed grown oxide material and having deposited oxide material. The grown oxide material is etched substantially selective relative to the deposited oxide material. In another considered aspect, a silicon surface is thermally oxidized to form substantially undoped silicon dioxide over a substrate. A substantially undoped silicon dioxide layer is chemical vapor deposited over the substrate, with at least some of the thermally grown silicon dioxide being outwardly exposed. The exposed thermally grown silicon dioxide layer is vapor etched substantially selective relative to the deposited silicon dioxide layer using an etch chemistry comprising substantially anhydrous HF and an organic primer.
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Micro)n Technology, Inc.
Pham Long
Wells, St. John, Roberts Gregory & Matkin P.S.
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