Plasma etching using xenon

Claim 1

A method for selectively etching a substrate having grain boundaries and a resist material thereon, comprising the steps of: (a) placing a substrate into an etch zone; (b) introducing a process gas absent oxygen into the etch zone, the process gas comprising (i) a primary etchant selected from the group consisting of chlorine, fluorine and bromine, (ii) a secondary etchant suitable for etching grain boundaries in the substrate, and (iii) xenon; and (c) generating a substantially oxygen-free plasma in the etch zone to form an etch gas from the process gas, wherein the etch gas selectively etches the substrate.

Claim 2

A method for selectively etching a substrate having grain boundaries and a resist material thereon, comprising the steps of: (a) placing a substrate into an etch zone; (b) introducing a process gas absent oxygen into the etch zone, the process gas comprising (i) a primary etchant selected from the group consisting of chlorine, fluorine and bromine, (ii) a secondary etchant suitable for etching grain boundaries in the substrate, and (iii) xenon; and (c) generating a substantially oxygen-free plasma in the etch zone to form an etch gas from the process gas, wherein the etch gas selectively etches the substrate.

Claim 19

A method for selectively etching a wafer, the method comprising the steps of: (a) placing a substrate selected from the group consisting of silicon and gallium arsenide wafers into an etch zone, the substrate having thereon (i) a plurality of layers selected from the group consisting of metal, oxide, nitride and silicide layers, and (ii) a resist material; (b) introducing a process gas into the etch zone, the process gas comprising (i) a primary etchant Cl 2 , (ii) a secondary etchant selected from the group consisting of BCl 3 , SiCl 4 , CCl 4 , and mixtures thereof, and (iii) xenon, wherein the volumetric flow ratio of secondary etchant to primary etchant is from about 0.1:1 to about 2:1, and the volumetric flow ratio of xenon to primary etchant is from about 0.1:1 to about 1:1; (c) generating a plasma in the etch zone to generate from the process gas an etch gas that etches the layers on the substrate in preference to the resist material, to create volatile etch byproduct compounds; and (d) removing the volatile etch byproduct compounds from the etch zone.

Claim 20

A method for selectively etching a wafer, the method comprising the steps of: (a) placing a substrate selected from the group consisting of silicon and gallium arsenide wafers into an etch zone, the substrate having thereon (i) a plurality of layers selected from the group consisting of metal, oxide, nitride and silicide layers, and (ii) a resist material; (b) introducing a process gas into the etch zone, the process gas comprising (i) a primary etchant Cl 2 , (ii) a secondary etchant selected from the group consisting of BCl 3 , SiCl 4 , CCl 4 , and mixtures thereof, and (iii) xenon, wherein the volumetric flow ratio of secondary etchant to primary etchant is from about 0.1:1 to about 2:1, and the volumetric flow ratio of xenon to primary etchant is from about 0.1:1 to about 1:1; (c) generating a plasma in the etch zone to generate from the process gas an etch gas that etches the layers on the substrate in preference to the resist material, to create volatile etch byproduct compounds; and (d) removing the volatile etch byproduct compounds from the etch zone.

Claim 25

A method for selectively etching layers on a silicon wafer, the method comprising the steps of: (a) placing a silicon wafer into an etch zone, the silicon wafer having thereon (i) a plurality of layers selected from the group consisting of metal, oxide, nitride, and silicide layers, and (ii) a resist material; (b) heating the wafer to a temperature above 70° C.; (c) introducing a process gas into the etch zone, the process gas comprising Cl 2 , BCl 3 , and xenon, wherein the volumetric flow ratio of BCl 3 to Cl 2 is from about 0.1:1 to about 2:1, and the volumetric flow ratio of xenon to Cl 2 is from about 0.1:1 to about 1:1; (d) maintaining the pressure in the etch zone at a pressure greater than about 1 mTorr; (e) generating an enhanced plasma in the etch zone by a method selected from the group consisting of electron cyclotron resonance, magnetically enhanced reactors, and inductively coupled plasma, so that an etch gas is generated from the process gas, and the etch gas etches the layers on the substrate in preference to the resist material, to create a volatile etch byproduct compounds; and (f) removing the volatile etch byproducts from the etch zone.

Claim 26

A method for selectively etching layers on a silicon wafer, the method comprising the steps of: (a) placing a silicon wafer into an etch zone, the silicon wafer having thereon (i) a plurality of layers selected from the group consisting of metal, oxide, nitride, and silicide layers, and (ii) a resist material; (b) heating the wafer to a temperature above 70° C.; (c) introducing a process gas into the etch zone, the process gas comprising Cl 2 , BCl 3 , and xenon, wherein the volumetric flow ratio of BCl 3 to Cl 2 is from about 0.1:1 to about 2:1, and the volumetric flow ratio of xenon to Cl 2 is from about 0.1:1 to about 1:1; (d) maintaining the pressure in the etch zone at a pressure greater than about 1 mTorr; (e) generating an enhanced plasma in the etch zone by a method selected from the group consisting of electron cyclotron resonance, magnetically enhanced reactors, and inductively coupled plasma, so that an etch gas is generated from the process gas, and the etch gas etches the layers on the substrate in preference to the resist material, to create a volatile etch byproduct compounds; and (f) removing the volatile etch byproducts from the etch zone.