Method of forming ruthenium thin film using plasma enhanced process

Abstract

A conventional method of forming a ruthenium thin film has a problem that conditions for improving a surface morphology are contrary to those for improving a step coverage, with respect to an oxygen fraction, a pressure, a temperature, etc. Accordingly, it is difficult to obtain a thin film having the improved properties in both the surface morphology and the step coverage. This invention provides three methods for improving both the surface morphology and the step coverage. As one method of forming the ruthenium thin film, a ruthenium seed layer is first formed using a PECVD process and then a ruthenium thin film is deposited using a thermal CVD process. As another method, a first ruthenium thin film is deposited using a thermal CVD process and then a second ruthenium thin film is formed on the first ruthenium thin film using a PECVD process. As further another method, a ruthenium thin film is deposited using a thermal CVD process and then a surface of the ruthenium thin film is processed using an oxygen containing plasma. According to these methods, both the surface morphology and the step coverage can be improved.

Dependencies are inferred from the claim text.