| abstract |
The present disclosure pertains to a method for plasma etching of low k materials, particularly polymeric-based low k materials. Preferably the polymeric-based materials are organic-based materials. The method employs an etchant plasma where the major etchant species are generated from a halogen other than fluorine and oxygen. The preferred halogen is chlorine. The volumetric (flow rate) ratio of the halogen:oxygen in the plasma source gas ranges from about 1:20 to about 20:1. The atomic ratio of the halogen:oxygen preferably falls within the range from about 1:20 to about 20:1. When the halogen is chlorine, the preferred atomic ratio of chlorine:oxygen ranges from about 1:10 to about 5:1. When this atomic ratio of chlorine:oxygen is used, the etch selectivity for the low k material over adjacent oxygen-comprising or nitrogen-comprising layers is advantageous, typically in excess of about 10:1. The plasma source gas may contain additives in an amount of 15% or less by volume which are designed to improve selectivity for the low k dielectric over an adjacent material, to provide a better etch profile, or to provide better critical dimension control, for example. When the additive contains fluorine, the amount of the additive is such that residual chlorine on the etched surface of the low k material comprises less than 5 atomic %. |