Conformal Deposition of High-Purity Copper Using Plasma Reactor with H Atom Source

We have studied the effects of H atoms on the removal of impurities in Cu thin films for plasma chemical vapor deposition (CVD) from Cu(hfac)2. In situ Fourier transform infrared (FT-IR) spectroscopic measurements show that H atoms are very effective in removing impurities in the film for substrate temperatures above 70°C. While H atoms are important to obtain high-purity Cu films, deposition rate and film conformality presumably depends on Cu-containing radicals, which are closely related to the degree of dissociation of Cu(hfac)2. Therefore, we have also demonstrated independent control of both concentration of H atoms and the degree of dissociation of Cu(hfac)2 by using a plasma CVD reactor equipped with an H atom source. Excellent film coverage of above 95% in a trench 0.4 µm wide and 3.25 µm deep is realized by their control.