Structure and method for post oxidation silicon trench bottom shaping
First Claim
1. A semiconductor device comprising:
- a trench region disposed within a silicon substrate, the trench region including;
an outer trench having an outer trench sidewall defining an upper portion and a bottom portion of the outer trench, the upper portion of the outer trench having a first width that is substantially constant, the outer trench sidewall including a pattern in the bottom portion of the outer trench, the pattern including;
a first portion that decreases in width from the first width to a second width;
a second portion of substantially the second width;
a third portion that increases in width from the second width to a third width;
a fourth portion that decreases in width from the third width to a fourth width; and
an outer trench bottom surface that is substantially flat;
an oxide layer disposed on the sidewall of the outer trench and the bottom portion of the outer trench such that the oxide layer forms an inner trench within the outer trench, the inner trench having an inner trench sidewall that is substantially vertical and an inner trench bottom surface that is substantially flat; and
a floating coupled capacitor including a conductive material disposed within the inner trench.
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Accused Products
Abstract
A method of fabricating an LFCC device includes forming a first trench in a substrate that extends vertically from an upper surface to a depth within the substrate, the first trench having first sidewalls, a first bottom, and a pattern formed on the first sidewalls near the first bottom of the trench, and forming an oxide layer on the first sidewalls and first bottom of the first trench that leaves a second trench located within the first trench and is separated from the first trench by the oxide layer. The second trench has second sidewalls that are substantially vertical without showing the pattern and a second bottom that is substantially flat. The pattern compensates for the difference in oxidation rates between the bottom of the first trench and the first sidewalls. The LFCC structure includes a first trench with the pattern.
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Citations
18 Claims
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1. A semiconductor device comprising:
a trench region disposed within a silicon substrate, the trench region including; an outer trench having an outer trench sidewall defining an upper portion and a bottom portion of the outer trench, the upper portion of the outer trench having a first width that is substantially constant, the outer trench sidewall including a pattern in the bottom portion of the outer trench, the pattern including; a first portion that decreases in width from the first width to a second width; a second portion of substantially the second width; a third portion that increases in width from the second width to a third width; a fourth portion that decreases in width from the third width to a fourth width; and an outer trench bottom surface that is substantially flat; an oxide layer disposed on the sidewall of the outer trench and the bottom portion of the outer trench such that the oxide layer forms an inner trench within the outer trench, the inner trench having an inner trench sidewall that is substantially vertical and an inner trench bottom surface that is substantially flat; and a floating coupled capacitor including a conductive material disposed within the inner trench. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A semiconductor device comprising:
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an outer trench including; a bottom portion of the outer trench including a pattern; and a sidewall of the outer trench in an upper portion of the outer trench, the sidewall of the outer trench being substantially vertical, the upper portion of the outer trench having a first width that is substantially constant; and an oxide layer disposed on the sidewall of the outer trench and disposed on the bottom portion of the outer trench such that the oxide layer forms an inner trench within the outer trench, the inner trench having a sidewall of the inner trench that is substantially vertical, the pattern of the outer trench being configured to compensate for a difference in oxidation rates between the bottom portion of the outer trench and the sidewall of the outer trench, the pattern including; a first portion that decreases in width from the first width to a second width; a second portion of substantially the second width; a third portion that increases in width from the second width to a third width; and a fourth portion that decreases in width. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A transistor comprising:
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an active drift region configured to, when in an on state, conduct electricity between a source region and a drain region; and a conductive material disposed within an inner trench, the inner trench including an inner trench sidewall that is substantially vertical, and the inner trench being separated from an outer trench by an oxide layer, the outer trench having a pattern in a bottom portion of the outer trench and an outer trench sidewall in an upper portion of the outer trench, the upper portion of the outer trench having a substantially constant first width, the pattern including; a first portion that decreases in width from the first width to a second width; a second portion of substantially the second width; a third portion that increases in width from the second width to a third width; and a fourth portion that decreases in width. - View Dependent Claims (17, 18)
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Specification