Use of hydrocarbon addition for the elimination of micromasking during etching of organic low-k dielectrics

Claim 1

A method for etching a feature in a dielectric layer of a wafer, the method comprising: disposing the wafer within a reaction chamber; introducing a flow of an etchant gas comprising a hydrocarbon additive and an active etchant into the reaction chamber, wherein the hydrocarbon is selected from a group consisting of CH 4 , C 2 H 4 , and C 2 H 6 , wherein the hydrocarbon has a flow rate of at least 1 sccm, wherein a ratio of the flow of active etchant to the flow of hydrocarbon additive is from 10,000:1 to 100:50, wherein if the active etchant includes nitrogen gas then the etchant gas must also include a reducing gas; forming a plasma from the etchant gas within the reaction chamber; etching the feature in at least a portion of the dielectric layer, wherein the dielectric layer is below a hardmask layer; and simultaneously forming from the hydrocarbon and etching away a polymer layer above the hardmask layer to reduce hardmask sputtering.

Claim 2

A method for etching a feature in a dielectric layer of a wafer, the method comprising: disposing the wafer within a reaction chamber; introducing a flow of an etchant gas comprising a hydrocarbon additive and an active etchant into the reaction chamber, wherein the hydrocarbon is selected from a group consisting of CH 4 , C 2 H 4 , and C 2 H 6 , wherein the hydrocarbon has a flow rate of at least 1 sccm, wherein a ratio of the flow of active etchant to the flow of hydrocarbon additive is from 10,000:1 to 100:50, wherein if the active etchant includes nitrogen gas then the etchant gas must also include a reducing gas; forming a plasma from the etchant gas within the reaction chamber; etching the feature in at least a portion of the dielectric layer, wherein the dielectric layer is below a hardmask layer; and simultaneously forming from the hydrocarbon and etching away a polymer layer above the hardmask layer to reduce hardmask sputtering.