Effects of hydrogen plasma treatment of the underlying TaSiN film surface on the copper nucleation in copper MOCVD

초록

MOCVD is one of the major deposition techniques for Cu thin films and Ta-Si-N is one of promising barrier metal candidates for Cu with high thermal stability. Effects of hydrogen plasma pretreatment of the underlying Ta-Si-N film surface on the Cu nucleation in Cu MOCVD were investigated using scanning electron microscopy, X-ray photoelectron spectroscopy and Auger electron emission spectroscopy analyses. Cu nucleation in MOCVD is enhanced as the rf-power and the plasma exposure time increase in the hydrogen plasma pretreatment. The optimal plasma treatment process condition is the rf-power of 40W and the plasma exposure time of 2 min. The hydrogen gas flow rate in the hydrogen plasma pretreatment process does not affect Cu nucleation much. The mechanism through which Cu nucleation is enhanced by the hydrogen plasma pretreatment of the Ta-Si-N film surface is that nitrogen and oxygen atoms at the Ta-Si-N film surface is effectively removed by the plasma treatment. Consequently the chemical composition changes from Ta-Si-N(O) into Ta-Si at the Ta-Si-N film surface, which is favorable for Cu nucleation.