Effects of cesium ion-implantation on mechanical and electrical properties of organosilicate low-k films

The effects of cesium (Cs) ion-implantation on uncured and ultraviolet (UV)-cured plasmaenhanced chemical-vapor-deposited (PECVD) organosilicate low dielectric constant (low-k) (SiCOH) films have been investigated. The mechanical properties, including the elastic modulus and hardness, of the SiCOH low-k films are improved by up to 29.9% with Cs implantation, and further up to 51.8% after annealing at 400°C in a N2 ambient. These improvements in mechanical properties are attributed to an enhancement of the Si-O-Si network structure. The kvalue of the SiCOH films increased slightly after Cs implantation, and increased further after annealing. These increases are attributed to two carbon-loss mechanisms, i.e. the carbon loss due to Si-CH3 bond breakage from implanted Cs ions, and the carbon loss due to oxidation during the annealing. These results indicate that Cs ion implantation could be a supplement to or a substitution for the incumbent UV curing method for processing SiCOH low-k films.