Influence of crystallographic orientation on dry etch properties of TiN

Abstract

A study of the impact of physical vapor deposition conditions on the etch properties of TiN has been conducted using a transformer coupled plasma. This work focuses only on a Cl2-based etch plasma. It is shown that the crystallographic orientation of TiN, observed from x-ray diffraction spectra, has a major influence on the etch behavior. Etch yields at varying dry etch conditions of two types of TiN, with different crystallographic orientations, have been studied quantitatively. The high roughness which is created during plasma exposure was identified as being the result of different etch rates of grains and intergranular material at the grain boundaries. Moreover, it is shown that TiN(111) is more difficult to etch, resulting in more pronounced roughness, than TiN(200), which is easier to etch, resulting in smoother surfaces for certain process conditions.