| abstract |
A method of etching an organic dielectric layer (10) on a substrate (15) with a high etching rate and a high etching selectivity ratio. The organic dielectric layer (10) comprises a low k dielectric material, such as a silicon-containing organic polymer, for example, benzocyclobutene. A patterned hard mask layer (20) of silicon oxide or nitride is formed on the organic dielectric layer (10). An energized process gas comprises an oxygen-containing gas for etching the organic dielectric layer (10), a non-reactive gas for removing dissociated material to enhance the etching rate, and optionally, passivating gas for forming passivating deposits on sidewalls (90) of freshly etched features to promote anisotropic etching. Preferably, during etching, the temperature of substrate (15) is maintained at a low temperature of from about -30° to +40° to enhance the rate of etching of the dielectric layer. The etching method is particularly useful for forming interconnect plugs in c vias (100) etched through the organic dielectric layer (10) by a dual damascene process. |