The present invention provides a method for purifying ruthenium sources to obtain high purity ruthenium metal and form a ruthenium metal pattern on a semiconductor substrate without the need for high temperature processing or a complex series of wet processes. A gas stream including ozone (O3) is brought into contact with a ruthenium source in one or more reaction vessels to form ruthenium tetraoxide (RuO4), a compound that is a gas at the reaction conditions. The ruthenium tetraoxide, along with unreacted ozone and the remainder of the gas stream is then fed into a collection vessel where the gaseous ruthenium tetraoxide is reduced to form a ruthenium dioxide (RuO2) layer on a semiconductor substrate. The deposited ruthenium dioxide is then reduced, preferably with hydrogen, to produce highly pure ruthenium metal that may be, in turn, patterned and dry etched using ozone as an etchant gas.