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US 6,429,148 B1Granted
Anisotropic formation process of oxide layers for vertical transistors
AssigneeProMOS Technologies Inc.
InventorsYu-Ping Chu, Yu-Wen Chu
Life of this patent
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Abstract
The method of the present invention forms a thin oxide layer on the circumferential wall of a recess in a trench and, at the same time, forms a thick oxide layer on the bottom surface of the recess. The thick oxide layer serves as the trench top oxide and the thin oxide layer serves as the gate oxide.
Claims8
A method for forming a thick oxide layer on a bottom surface of a recess and a thin oxide layer on a circumferential wall of said recess, wherein said recess is a part of a trench formed in a substrate, and said circumferential wall is perpendicular to said bottom surface, comprising the steps of:
- implanting inert gas ions into said bottom surface at a direction parallel to said circumferential wall;
- and
- thermally processing said substrate by a thermal oxidation process to form said thick oxide layer on said bottom surface and said thin oxide layer on said circumferential wall.
Dependencies are inferred from the claim text.