US5814563A — Method for etching dielectric using fluorohydroca…

Claim 1

Independent Claim 176 words

A method of selectively etching a substrate having a dielectric layer with resist thereon, the method comprising the steps of: (a) placing the substrate in a process zone; (b) introducing into the process zone, a process gas comprising (i) fluorohydrocarbon gas for forming fluorine-containing etchant species capable of etching the dielectric layer, (ii) NH 3 -generating gas having a liquefaction temperature L T in a range of temperatures ΔT of from about -60° C. to about 20° C., the volumetric flow ratio of fluorohydrocarbon gas to NH 3 -generating gas being from about 2.5:1 to about 7:1, and (iii) carbon-oxygen gas, the volumetric flow ratio of carbon-oxygen gas to fluorohydrocarbon gas being from about 0.1:1 to about 1:1; (c) maintaining the substrate at temperatures within about ±50° C. of the liquefaction temperature L T ; and (d) forming a plasma from the process gas to etch the dielectric layer on the substrate at an etch rate of greater than 600 nm/minute, and an etching selectivity ratio for etching dielectric relative to underlying polysilicon of substantially ∞:1.

Claim 2

Independent Claim 176 words

A method of selectively etching a substrate having a dielectric layer with resist thereon, the method comprising the steps of: (a) placing the substrate in a process zone; (b) introducing into the process zone, a process gas comprising (i) fluorohydrocarbon gas for forming fluorine-containing etchant species capable of etching the dielectric layer, (ii) NH 3 -generating gas having a liquefaction temperature L T in a range of temperatures ΔT of from about -60° C. to about 20° C., the volumetric flow ratio of fluorohydrocarbon gas to NH 3 -generating gas being from about 2.5:1 to about 7:1, and (iii) carbon-oxygen gas, the volumetric flow ratio of carbon-oxygen gas to fluorohydrocarbon gas being from about 0.1:1 to about 1:1; (c) maintaining the substrate at temperatures within about ±50° C. of the liquefaction temperature L T ; and (d) forming a plasma from the process gas to etch the dielectric layer on the substrate at an etch rate of greater than 600 nm/minute, and an etching selectivity ratio for etching dielectric relative to underlying polysilicon of substantially ∞:1.

Claim 3

Dependent Claim 51 words

The method of claim 1, wherein the NH 3 -generating gas comprises a sticking coefficient of at least about 0.1, and wherein at least a portion of the gas chemically adheres to the substrate surface at the liquefaction temperatures of the gas, thereby enhancing the etching rate of the dielectric layer.

Claim 4

Dependent Claim 46 words

The method of claim 1, wherein the NH 3 -generating gas is selected from the group consisting of NH 3 , NH 4 OH, CH 3 NH 2 , C 2 H 5 NH 2 , C 3 H 8 NH 2 , and mixtures thereof.

Claim 5

Dependent Claim 44 words

The method of claim 1, wherein the fluorohydrocarbon gas is selected from the group consisting of CHF 3 , CH 3 F, C 2 HF 5 , C 2 H 2 F 2 , C 2 H 4 F 2 , and mixtures thereof.

Claim 6

Dependent Claim 29 words

The method of claim 1, wherein the carbon-oxygen gas is selected from the group consisting of CO, CO 2 , HCOOH, HCHO, CH 3 COOH, and CH 3 OH.

Claim 7

Dependent Claim 49 words

The method of claim 1, wherein the process gas further comprises fluorocarbon gas absent hydrogen that is selected from the group consisting of CF 4 , C 2 F 6 , C 3 F 8 , C 4 F 8 , C 4 F 10 , and mixtures thereof.

Claim 8

Dependent Claim 39 words

The method of claim 6, wherein the fluorohydrocarbon gas comprises CHF 3 , and the fluorocarbon gas comprises CF 4 , and wherein the volumetric flow ratio of CF 4 :CHF 3 is from about 0:1 to about 1:2.

Claim 9

Dependent Claim 42 words

The method of claim 1, wherein the process gas further comprises an inert gas selected from the group consisting of argon, xenon, neon, krypton, and helium, and wherein the volumetric flow ratio of inert:fluorohydrocarbon gas is from about 1:1 to about 3:1.

Claim 10

Dependent Claim 28 words

The method of claim 1, wherein the dielectric layer is selected from the group consisting of silicon dioxide, undoped silicate glass, phophosilicate glass, borophosphosilicate glass, and combinations thereof.

Claim 11

Independent Claim 211 words

A method of selectively etching dielectric comprising silicon oxide or silicon nitride layers on underlying polysilicon on a substrate, the method comprising the steps of: (a) placing the substrate in a process zone; (b) introducing into the process zone, a process gas comprising (i) fluorohydrocarbon gas selected from the group consisting of CHF 3 , CH 3 F, C 2 HF 5 , C 2 H 2 F 2 , and C 2 H 4 F 2 , (ii) fluorocarbon gas absent hydrogen selected from the group consisting of CF 4 , C 2 F 6 , C 3 F 8 , C 4 F 8 and C 4 F 10 , (iii) NH 3 , (iv) CO, and (v) inert gas, wherein the volumetric flow ratio of fluorohydrocarbon gas to NH 3 is from about 2.5:1 to about 7:1, the volumetric flow ratio of fluorocarbon gas to fluorohydrocarbon gas is from about 0:1 to about 1:2, and the volumetric flow ratio of CO to fluorohydrocarbon gas is from about 0.1:1 to about 1:1; and (c) forming a plasma from the process gas to etch the dielectric at an etch rate of greater than 600 nm/minute, and an etching selectivity ratio for etching dielectric relative to underlying polysilicon of substantially ∞:1.

Claim 12

Independent Claim 211 words

A method of selectively etching dielectric comprising silicon oxide or silicon nitride layers on underlying polysilicon on a substrate, the method comprising the steps of: (a) placing the substrate in a process zone; (b) introducing into the process zone, a process gas comprising (i) fluorohydrocarbon gas selected from the group consisting of CHF 3 , CH 3 F, C 2 HF 5 , C 2 H 2 F 2 , and C 2 H 4 F 2 , (ii) fluorocarbon gas absent hydrogen selected from the group consisting of CF 4 , C 2 F 6 , C 3 F 8 , C 4 F 8 and C 4 F 10 , (iii) NH 3 , (iv) CO, and (v) inert gas, wherein the volumetric flow ratio of fluorohydrocarbon gas to NH 3 is from about 2.5:1 to about 7:1, the volumetric flow ratio of fluorocarbon gas to fluorohydrocarbon gas is from about 0:1 to about 1:2, and the volumetric flow ratio of CO to fluorohydrocarbon gas is from about 0.1:1 to about 1:1; and (c) forming a plasma from the process gas to etch the dielectric at an etch rate of greater than 600 nm/minute, and an etching selectivity ratio for etching dielectric relative to underlying polysilicon of substantially ∞:1.

Claim 13

Dependent Claim 27 words

The method of claim 10, wherein the substrate is maintained at temperatures within about ±50° C. of a liquefaction temperature L T of the NH 3 gas.

Claim 14

Independent Claim 144 words

A method of treating a substrate comprising silicon dioxide or silicon nitride layers over underlying polysilicon, the method comprising the steps of: (a) placing the substrate in a process zone; (b) introducing into the process zone, a process gas comprising (i) CHF 3 , (ii) CF 4 , (iii) NH 3 , (iv) CO, and (v) inert gas, wherein the volumetric flow ratio of CHF 3 :NH 3 is from about 2.5:1 to about 7:1, the volumetric flow ratio of CF 4 :CHF 3 is from about 0:1 to about 1:2, and the volumetric flow ratio of CO:CHF 3 is from about 0.1:1 to about 1:1; and (c) forming a plasma from the process gas to etch the silicon oxide or silicon nitride layers at an etch rate of greater than 600 nm/minute, and an etching selectivity ratio relative to polysilicon of substantially ∞:1.

Claim 15

Independent Claim 144 words

A method of treating a substrate comprising silicon dioxide or silicon nitride layers over underlying polysilicon, the method comprising the steps of: (a) placing the substrate in a process zone; (b) introducing into the process zone, a process gas comprising (i) CHF 3 , (ii) CF 4 , (iii) NH 3 , (iv) CO, and (v) inert gas, wherein the volumetric flow ratio of CHF 3 :NH 3 is from about 2.5:1 to about 7:1, the volumetric flow ratio of CF 4 :CHF 3 is from about 0:1 to about 1:2, and the volumetric flow ratio of CO:CHF 3 is from about 0.1:1 to about 1:1; and (c) forming a plasma from the process gas to etch the silicon oxide or silicon nitride layers at an etch rate of greater than 600 nm/minute, and an etching selectivity ratio relative to polysilicon of substantially ∞:1.

Claim 16

Dependent Claim 27 words

The method of claim 12, wherein the substrate is maintained at temperatures within about ±50° C. of a liquefaction temperature L T of the NH 3 gas.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2001-09-28	2002-03-30	2002-09-29	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2005-09-28	2006-03-30	2006-09-29	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2009-09-28	2010-03-30	2010-09-29	$7700.00	Window Closed / Lapsed

Method for etching dielectric using fluorohydrocarbon gas, NH3 -generating gas, and carbon-oxygen gas

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