Plasma-enhanced metal organic chemical vapor deposition of high purity copper thin films using plasma reactor with the H atom source

In situ Fourier-transform infrared measurements have been carried out to study the effects of H atoms on removing impurities in Cu thin films during plasma enhanced metal organic chemical vapor deposition (PEMOCVD) using bis(hexafluoroacetylacetonato) copper (II), Cu(hfac)₂ as a source material. The results show that H atoms are very effective in removing impurities in the film, as well as on its surface. Based on such knowledge regarding the effects of H atoms, a PEMOCVD reactor equipped with an H atom source is developed to control both densities of H atoms and Cu-contained radicals independently. High purity (≈ 100%) Cu films of a low resistivity of 2 μΩ cm can be deposited for a H₂ gas volume fraction of 50%-67% by using the H atom source, while the high purity films were obtained only for a very high H₂ gas volume fraction above about 90% in the case of no H atom source as reported previously. This feature opens up a possibility of deposition of high quality Cu films at a high rate using the reactor equipped with the H atom source, since a gas volume fraction of Cu metal organic material can be increased by more than five times.