method for etching organic low - k dielectric using ammonia , nh3 , as an active etchant . processes using ammonia results in at least double the etch rate of organic low - k dielectric materials than processes using n2 / h2 chemistries , at similar process conditions . the difference is due to the much lower ionization potential of nh3 versus n2 in the process chemistry , which results in significantly higher plasma densities and etchant concentrations at similar process conditions .