Effects of O-2 plasma treatment on the chemical and electric properties oflow-k SiOF films

With the progress of ULSI technology, materials with low dielectric constan t are required to replace SiO2 film as the interlayer to scale down the int erconnection delay. Fluorinated Si oxide thin films (SiOF) are a promising material for the low dielectric constant and the process compatibility in e xisting technology. However, SiOF films are liable to absorb moisture when exposed to air. By treating the SiOF films with O-2 plasma, it was found th at the moisture resistibility of SiOF films was remarkably improved. The me chanism of the improvement in stability of dielectric constant was investig ated. The results show that: 1) F atoms dissociated from the films and the bond angle of Si-O-Si decreased. 2) The plasma treatment enhanced the stren gth of Si-F bonds by removing unstable =SiF2 structures in the films. Resis tibility of SiOF films in moisture was improved.