Separation of ion and photon damage effects on novel dielectric materials during plasma exposure

Summary form only given. Damage induced in high and low-k thin dielectric films by exposure to an electron cyclotron resonance (ECR) plasma was investigated. The effects of charged-particle bombardment and vacuum ultraviolet radiation were separated by varying plasma parameters and using a capillary-array window. Damage was measured by examining the surface potential, defect concentrations, chemical and physical structures after plasma exposure. For high-k dielectric films (HfO₂), most of the charge accumulation came from the ion fluence, while photon fluence introduced most of the defect-state modifications. It was further shown that, during plasma exposure, UV photons penetrate through the dielectric layer and cause modifications of the defect states. Based on the results, optimized conditions were found to minimize both charge accumulation and defect state formation during plasma exposure. For low-k porous organosilicate glass (SiCOH) dielectric films, it was found that during argon ECR plasma processing, 75% of the charge accumulation comes from ions at the surface, while 25% of the charge accumulation occurs from charge trapped within the bulk of the dielectric film due to photon bombardment. Fourier transform infrared spectroscopy (FTIR) results showed no significant change except for the physical Si-(CH₃)_X bonds. The results were verified by ellipsometric measurements. It was shown that both the dielectric thickness and the dielectric constant changed during plasma exposure.