Integration and Characterization of Low Carbon Content SiO_xC_yH_z Low kappa Materials for < 0.18 mu m Dual Damascene Application

摘要

A CVD-based low K film was evaluated for inter-metal dielectric in < 0.18 mu rn generation devices. The film was deposited by conventional rf PECVD method using organosilane compound and oxygen. The measured dielectric constant of the film was 2.7 approx 2.75. The kappa value of the film was stable over several weeks and the moisture absorption was minimal. The chemical composition was in the form of SiO_xC_yH_z, where the carbon content was less than 5 atomic %. Blanket film integration study was conducted to find out the manufacturing compatibility. The largest increase in kappa value occurred during etching and ashing steps. However, SIMS compositional analysis revealed that the damage from these steps were limited to within top 300 A, and the initial low kappa value was recovered after the top damaged layer was removed by CMP. The final integrated dielectric constant was less than 3.0. The film density was measured as 1.4, compared to 2.3 g/cm~3 of conventional SiO2. The low density of the film resulted from the termination of SiO2 network structures by Si-CH3 and Si-H.