Etchant and method of use
First Claim
Patent Images
1. A method of removing silicon dioxide upon an etch stop layer, the method comprising:
- providing a silicon dioxide dielectric layer upon an etch stop layer, wherein the etch stop layer comprises refractory metal nitride;
providing a gaseous etchant including a hydrofluorocarbon etch gas and including an etch selectivity enhancing fluorocarbon compound selected from the group consisting of CF4, C2F6, C4F8, C5F6, C5F8, and combinations thereof; and
exposing the silicon dioxide dielectric layer to the gaseous etchant in an etch chamber having a roof comprising silicon and having a temperature in a range from about 100°
C. to about 200°
C.
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Abstract
The present invention relates to a method of anisotropically etching a semiconductive substrate uses a hydrofluorocarbon etch gas with an etch selectivity fluorocarbon gas that previously was used to enhance oxide etching but not nitride selectivity. The present invention uses the fluorocarbon gas under conditions that enhance selectivity of the etch to nitride with respect to a bulk dielectric material such as doped and undoped silicon dioxide.
41 Citations
35 Claims
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1. A method of removing silicon dioxide upon an etch stop layer, the method comprising:
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providing a silicon dioxide dielectric layer upon an etch stop layer, wherein the etch stop layer comprises refractory metal nitride;
providing a gaseous etchant including a hydrofluorocarbon etch gas and including an etch selectivity enhancing fluorocarbon compound selected from the group consisting of CF4, C2F6, C4F8, C5F6, C5F8, and combinations thereof; and
exposing the silicon dioxide dielectric layer to the gaseous etchant in an etch chamber having a roof comprising silicon and having a temperature in a range from about 100°
C. to about 200°
C. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of etching a self-aligned contact comprising:
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providing a refractory metal nitride etch stop layer on each gate stack in a pair of adjacent, spaced apart gate stacks situated over a semiconductive substrate and a silicon dioxide dielectric layer on the silicon nitride layer;
placing the semiconductive substrate in an etch chamber, wherein the etch chamber has a roof comprising silicon;
etching into the silicon dioxide dielectric layer in the etch chamber, wherein the etch chamber has a temperature in a range from about 100°
C. to about 200°
C., to form a self aligned contact hole between the pair of gate stacks without substantially etching the etch stop layer on the sidewalls of the contact hole, using gaseous CHF3 and an etch selectivity enhancing compound selected from the group consisting of CF4, C2F6, C4F8, C5F6, C5F8, and combinations thereof;
etching the contact hole to the semiconductive substrate; and
stopping said etching after the etch exposes the silicon nitride layer.
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10. A method of removing silicon dioxide dielectric upon an etch stop layer that is situated upon a semiconductive substrate positioned within an etch chamber, the method comprising:
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etching the silicon dioxide dielectric to a first depth with a first etch recipe including a hydrofluorocarbon, the first etch recipe having a first selectivity to the etch stop layer, wherein the etch stop layer is refractory metal nitride;
etching the silicon dioxide dielectric to a second depth with a second etch recipe including the hydrofluorocarbon and an etch selectivity enhancing compound comprising a fluorocarbon selected from the group consisting of CF4, C2F6, C4F8, C5F6, C5F8, and combinations thereof, the second etch recipe having a second selectivity to the etch stop layer, wherein the first selectivity is greater than the second selectivity; and
stopping the second etching upon the etch stop layer. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An etching method comprising:
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providing an etch chamber and a semiconductive substrate having thereon a bulk dielectric upon an underlying layer that comprises a refractory metal nitride;
etching the bulk dielectric with a first etch recipe including hydrofluorocarbon and an etch selectivity enhancing gas comprising fluorocarbon in a first proportion; and
etching the bulk dielectric with a second etch recipe including hydrofluorocarbon and the etch selectivity enhancing gas in a second proportion that is greater than the first proportion, wherein each selectivity to the underlying layer is greater for the second etch recipe than etch selectivity for the first etch recipe. - View Dependent Claims (22, 23, 24, 25, 26, 32)
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27. In an etch chamber having a roof composed of silicon, a semiconductive substrate support for supporting a semiconductive substrate having a bulk dielectric disposed upon an etch stop layer, and having a silicon ring surrounding the semiconductive substrate support, an etching method comprising:
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maintaining the temperature of;
the roof of the etch chamber in a range from about 135°
C. to about 200°
C.;
the semiconductive substrate support in a range from about −
30°
C. to about 80°
C.; and
the silicon ring in a range from about 180°
C. to about 250°
C.;
etching a recess having an aspect ratio of at least 5;
1 in the bulk dielectric using a gaseous etchant including CHF3 and an etch selectivity enhancing compound comprising carbon and fluorine;
etching the recess to the semiconductive substrate; and
stopping etching the recess after the etch stop layer has been exposed, wherein the etch stop layer comprises refractory metal nitride. - View Dependent Claims (28, 29, 30)
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31. A method of determining a specific etch recipe for etching silicon dioxide with predetermined selectivity to an etch stop layer underlying the silicon dioxide, the method comprising:
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etching silicon dioxide with a gaseous etchant including a hydrofluorocarbon and an etch selectivity enhancing gas comprising carbon and fluorine to obtain a selectivity to the etch stop layer, wherein the etch stop layer comprises refractory metal nitride;
repeating said etching with different amounts of said etch selectivity enhancing gas comprising carbon and fluorine to correspondingly obtain different selectivities to said etch stop layer;
selecting an amount of said different amounts of said etch selectivity enhancing gas corresponding to a desired etch selectivity to said etch stop layer; and
etching silicon dioxide with a gaseous etchant including the hydrofluorocarbon and said selected amount of said selectivity gas to obtain said desired selectivity to the etch stop layer. - View Dependent Claims (33, 34, 35)
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Specification