High performance strained CMOS devices
First Claim
Patent Images
1. A process of forming a semiconductor structure, comprising:
- forming a structure comprised of a silicon layer, a silicon dioxide layer on the silicon layer, and a silicon nitride layer on the silicon dioxide layer; and
forming a shallow trench isolation on the structure based on a determined distance between the shallow trench isolation and an active device, the shallow trench isolation formed to have a first shallow trench isolation side having at least one overhang, in a first direction, selectively configured to prevent bird'"'"'s beak formations where compressive stresses by the bird'"'"'s beak formations would degrade device performance based on the determined distance, and a second shallow trench isolation side being transverse to the first shallow trench side and being devoid of an overhang when the determined distance prevents the bird'"'"'s beak formations.
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Abstract
A semiconductor device and method of manufacture provide an n-channel field effect transistor (nFET) having a shallow trench isolation with overhangs that overhang Si—SiO2 interfaces in a direction parallel to the direction of current flow and in a direction transverse to current flow. The device and method also provide a p-channel field effect transistor (pFET) having a shallow trench isolation with an overhang that overhangs Si—SiO2 interfaces in a direction transverse to current flow. However, the shallow trench isolation for the pFET is devoid of overhangs, in the direction parallel to the direction of current flow.
52 Citations
17 Claims
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1. A process of forming a semiconductor structure, comprising:
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forming a structure comprised of a silicon layer, a silicon dioxide layer on the silicon layer, and a silicon nitride layer on the silicon dioxide layer; and forming a shallow trench isolation on the structure based on a determined distance between the shallow trench isolation and an active device, the shallow trench isolation formed to have a first shallow trench isolation side having at least one overhang, in a first direction, selectively configured to prevent bird'"'"'s beak formations where compressive stresses by the bird'"'"'s beak formations would degrade device performance based on the determined distance, and a second shallow trench isolation side being transverse to the first shallow trench side and being devoid of an overhang when the determined distance prevents the bird'"'"'s beak formations. - View Dependent Claims (2, 3, 4)
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5. A process of forming a pFET structure, comprising:
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forming a structure comprised of a silicon layer, a silicon dioxide layer on the silicon layer, and a silicon nitride layer on the silicon dioxide layer; and forming a shallow trench isolation having a first shallow trench isolation side with an overhang over a portion of the silicon layer and the silicon dioxide layer in a transverse direction, based on a distance between an active device and the shallow trench isolation, to prevent a bird'"'"'s beak formation, and a second shallow trench isolation side being devoid of an overhang in a direction parallel to a direction of current flow. - View Dependent Claims (6)
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7. A method of forming a device, comprising:
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forming a silicon dioxide layer over a silicon layer; forming a silicon nitride layer over the silicon dioxide layer; forming at least one shallow trench isolation with an overhang by; etching the silicon nitride layer, silicon dioxide layer and a portion of the silicon layer using a dry or wet etch process to form the at least one shallow trench isolation; etching portions of the silicon nitride layer further back causing the silicon nitride layer to recede relative to side walls of the at least one shallow trench isolation sufficient to prevent oxidation in a determined portion of the device; filling the at least one shallow trench isolation and receded areas with silicon dioxide; planarizing a surface of the silicon dioxide; and etching selective portions of the silicon nitride layer, wherein the forming of the overhang is controlled by selectively applying a photoresist or hardmask to prevent etchant from undercutting determined areas during the etching portions step such that areas protected by the photoresist or hardmask do not exhibit pull-back required for formation of the overhang, and wherein the overhang, in a first direction, is selectively configured to prevent bird'"'"'s beak formations where compressive stresses by the bird'"'"'s beak formations would degrade device performance. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of forming a device, comprising:
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forming a silicon dioxide layer over a silicon layer; forming a silicon nitride layer over the silicon dioxide layer; forming at least one shallow trench isolation with an overhang by; etching the silicon nitride layer, silicon dioxide layer and a portion of the silicon layer using a dry or wet etch process to form the at least one shallow trench isolation; etching portions of the silicon nitride layer further back causing the silicon nitride layer to recede relative to side walls of the at least one shallow trench isolation sufficient to prevent oxidation in a determined portion of the device; filling the at least one shallow trench isolation and receded areas with silicon dioxide; planarizing a surface of the silicon dioxide; and etching selective portions of the silicon nitride layer, wherein the forming of the overhang is controlled by selectively applying a photoresist or hardmask to prevent etchant from undercutting determined areas during the etching portions step such that areas protected by the photoresist or hardmask do not exhibit pull-back required for formation of the overhang, and wherein the overhang for nFET devices are in directions of and transverse to current flow. - View Dependent Claims (17)
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Specification