Dual cap layer in damascene interconnection processes

Abstract

Damascene methods for forming copper conductors () are disclosed. According to the disclosed method, a dual cap layer () is formed over an organosilicate glass insulating layer () prior to the etching of a via or trench toward an underlying conductor (). The dual cap layer includes a layer of silicon carbide () and a layer of silicon nitride (). The silicon carbide layer () and silicon nitride layer () can be deposited in either order relative to one another. The silicon carbide layer () maintains the critical dimension of the via or trench as it is etched through the insulating layer (), while the silicon nitride layer () inhibits the failure mechanism of resist poisoning. The method is applicable to single damascene processes, but may also be used in dual damascene copper processes.