THE EFFECTS OF PLASMA TREATMENT FOR LOW DIELECTRIC-CONSTANT HYDROGEN SILSESQUIOXANE (HSQ)

Low density materials, such as hydrogen silsesquioxane (HSQ), can offe r lower dielectric constants. With HSQ, a low value of K can be achiev ed if the density of Si-H bonding is maintained at a high level and th e formation of -OH bonds and absorption or creation of water in the fi lm is minimized. In this work, we have studied the use of hydrogen pla sma to improve the quality of HSQ. In addition, the effects of N-2 and O-2 plasma post-treatments on HSQ are investigated. The leakage curre nt of HSQ decreases as the H-2 plasma treatment time is increased. How ever, the leakage current of HSQ increases as the N-2 and O-2 plasma t reatment time is increased. A model is proposed to explain the role of hydrogen in HSQ. The hydrogen passivates the surface of porous HSQ. T he H-2 plasma treatment provides additional hydrogen passivation of th e HSQ. On the other hand, the N-2 and O-2 plasma treatments reduce the hydrogen passivation of HSQ. As a result, both the leakage current an d dielectric constant increase as the N-2 and O-2 plasma treatment tim e is increased. Finally, HSQ with H-2 plasma treatment is used as the intermetal dielectric in a multilevel interconnection structure. Consi stent with our model, the via resistance decreases with increasing H-2 plasma treatment time. (C) 1998 Elsevier Science S.A. All rights rese rved.