Atomic Layer Deposition of Ruthenium Thin Films for Copper Glue Layer

Ruthenium thin films were produced by atomic layer deposition (ALD) using an alternating supply of bis(ethylcyclopentadienyl)ruthenium and oxygen at a deposition temperature of 270°C. The relative ratio of the adsorbed on the film surface to the oxygen partial pressure in the following oxygen pulse determines whether Ru or film was obtained. At the range with higher relative ratio the film was composed of ruthenium, but the film deposited at the lower range was revealed to be ruthenium oxide. In case of the ruthenium thin film, the film thickness per cycle was saturated at 0.15 nm/cycle, and its resistivity was about 15 μΩ cm. The impurities of carbon and oxygen were incorporated into the film with less than 2 atom %. It was also demonstrated that the ruthenium thin films prepared by ALD can be used as an excellent glue layer to improve the interfacial adhesion of metallorganic chemical vapor deposited copper to TiN. Secondary ion mass spectroscopy analysis showed that the ruthenium glue layer suppressed the interfacial contaminants, such as carbon and fluorine, which originated from the metallorganic precursors of copper.