Selective etching of carbon-doped low-k dielectrics

A plasma etch process for selectively etching a layer of low-k dielectric material having a dielectric constant less than 4, comprising:

• introducing into a plasma etch chamber, in which the layer of low-k dielectric material is situated, an etching gas mixture comprising a fluorine-rich fluorocarbon or hydrofluorocarbon gas, a nitrogen-containing gas, and a hydrogen-rich hydrofluorocarbon gas;
• and
• maintaining a plasma of the etching gas mixture in the plasma etch chamber to etch the layer of low-k dielectric material, wherein the etching gas mixture is introduced into the plasma etch chamber by introducing the fluorine-rich fluorocarbon or hydrofluorocarbon gas at a first volumetric flow rate, the nitrogen-containing gas at a second volumetric flow rate, and a hydrogen-rich hydrofluorocarbon gas at a third volumetric flow rate, and wherein the ratio of the second volumetric flow rate to the first volumetric flow rate is about 1:4 to 2:1.

A plasma etch process for selectively etching a layer of low-k dielectric material having a dielectric constant less than 4, comprising:

• introducing into a plasma etch chamber, in which the layer of low-k dielectric material is situated, an etching gas mixture comprising a fluorine-rich fluorocarbon or hydrofluorocarbon gas, a nitrogen-containing gas, and a hydrogen-rich hydrofluorocarbon gas;
• and
• maintaining a plasma of the etching gas mixture in the plasma etch chamber to etch the layer of low-k dielectric material, wherein the etching gas mixture is introduced into the plasma etch chamber by introducing the fluorine-rich fluorocarbon or hydrofluorocarbon gas at a first volumetric flow rate, the nitrogen-containing gas at a second volumetric flow rate, and a hydrogen-rich hydrofluorocarbon gas at a third volumetric flow rate, and wherein the ratio of the third volumetric flow rate to the first volumetric flow rate is about 1:3 to 1:1.