ISOLATION STRUCTURE FOR TRENCH CAPACITORS AND FABRICATION METHOD THEREOF
First Claim
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1. A isolation structure of a trench capacitor, the trench capacitor being disposed in a deep trench of a substrate and comprising a conductive layer in the deep trench and a collar oxide layer disposed on a surface of a sidewall of the deep trench, the isolation structure comprising:
- a first isolation portion covering the conductive layer and filling a top opening of the deep trench, the first isolation portion having a first thickness; and
a second isolation portion directly contacting the first isolation portion and surrounding the deep trench without overlapping the deep trench, the second isolation portion having a second thickness larger than the first thickness.
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Abstract
An isolation structure of a trench capacitor of DRAM has a first isolation portion covering the trench capacitor and filling a top opening of the deep trench and a second isolation portion directly contacting the first isolation potion and surrounding the deep trench without overlapping the deep trench. The thickness of the second isolation portion is larger than the thickness of the first isolation portion.
11 Citations
19 Claims
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1. A isolation structure of a trench capacitor, the trench capacitor being disposed in a deep trench of a substrate and comprising a conductive layer in the deep trench and a collar oxide layer disposed on a surface of a sidewall of the deep trench, the isolation structure comprising:
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a first isolation portion covering the conductive layer and filling a top opening of the deep trench, the first isolation portion having a first thickness; and
a second isolation portion directly contacting the first isolation portion and surrounding the deep trench without overlapping the deep trench, the second isolation portion having a second thickness larger than the first thickness. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 19)
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9. A method of self-aligned fabricating an isolation structure of a trench capacitor, wherein the trench capacitor is disposed in a deep trench of a substrate having a pad layer thereon, the trench capacitor comprising:
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a conductive layer filled in the deep trench, wherein a top surface of the conductive layer and a sidewall of the pad layer define a recess; and
a collar oxide layer disposed on a surface of a sidewall of the deep trench;
the method comprising;
forming a mask layer and a dielectric layer in sequence on the substrate and a surface of the recess;
forming a photoresist layer on the dielectric layer, the photoresist layer having an opening that defines a shallow trench;
etching the dielectric layer, the mask layer, and the pad layer through the opening until the substrate is exposed; and
etching the substrate by taking the residual mask layer as a hard mask until a surface of the exposed substrate is lower than a top of the collar oxide layer, wherein the conductive layer and the collar oxide layer remain intact. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification