Subtractive Etching of Cu with Hydrogen-based Plasmas

Due to the inability to form volatile etch products at temperatures less than 180 degrees C, the damascene process has been the prevailing patterning technology for copper. A simple, hydrogen (H-2) plasma-based, low temperature etch process was developed to allow an alternative method to damascene technology. Cu thin films were etched by a H-2 plasma in an inductively coupled plasma (ICP) reactor at temperatures below room temperature (10 degrees C). This process achieved anisotropic Cu features and an etch rate of similar to 13 nm/min. Ion bombardment was a contributor to Cu removal. However, lower etch rates of Cu were observed in an Ar plasma than in the H-2 plasma, despite the fact that Ar is a more efficient sputter gas. Based on Cu etch rates and patterning results, the etch process involve both chemical and physical characteristics.