Patent ID: 8124516

Claim:
A method of forming dual damascene features in a porous low-k dielectric layer, comprising: forming vias in the porous low-k dielectric layer; forming an organic planarization layer over the porous low-k dielectric layer, wherein the organic layer fills the vias; forming a photoresist mask over the organic planarization layer; etching features into the organic planarization layer, further comprising: providing an etch gas, consists essentially of CO 2 or a mixture of CO 2 and CO; and forming a plasma from the CO 2 containing etch gas, which etches the organic planarization layer and exposes part of the porous low-k dielectric layer without damaging the porous low-k dielectric layer; etching trenches into the porous low-k dielectric layer using the organic planarization layer as a mask, wherein some of the organic planarization layer remains in the vias after etching trenches into the porous low-k dielectric layer; and stripping the organic planarization layer, wherein the organic planarization layer is removed from the vias during the stripping the organic planarization layer.