Abstract
An anisotropic inductive coupled plasma (ICP) soft etching using high-density Ar plasma and low incident energy, generally performed before metallization of interconnection, and which can uniformly remove the native oxide at the bottom of fine contact holes, is introduced. As a result, excellent ohmic characteristics can be achieved using ICP soft etching. A cross-sectional TEM (Transmission Electron Microscopy) -EELS (Electron Energy Loss Spectroscopy) was performed in order to compare interface layer generation at the contact hole in the ICP system with that generated in standard RF (Radio Frequency) diode etching. In the sample treated by ICP soft etching, reacted Ti silicide was observed at the bottom of the contact holes. Furthermore, the formation mechanism of stable ohmic contacts was theoretically analyzed using a Monte-Carlo topological simulation. From the results, we found that it is possible to prevent rem-iner denosition on the bottom of holes with 0.1μm diameter.
