Deposition Of CH₄-doped SiCOH Films And Investigation Of Properties

Low-k SiCOH films are prepared by electron cyclotron resonance chemical vapor deposition (ECR-CVD) by adding methane in decamethylcyclopentasioxane (D5) as source gas, and the lowest dielectric constant 2.45 is obtained when flow rate of methane is 2sccm. According to the analysis of FTIR and OES results, we speculate that the plasma environment rich in carbon and hydrogen is beneficial to the conservation of annular framework of D5. Large quantities of carbon and hydrogen element form Si-C and C-C bonds in the films connecting adjacent annular framework, which would decrease film density and cause continually decrease in dielectric constant.The influence of anneal atmosphere on structure and properties of films is investigated by annealing films respectively in air and nitrogen. In this process, films react with the active element in anneal atmosphere and recombine structure because of the high temperature. The film annealed in air is similar to silicon dioxide in structure. The appearance of polar bond Si-OH and the shrinkage of film cause the increase of dielectric constant. Many chain link structures form in the film annealed in nitrogen. Decrease of connecting networks is the main reason for the increase of dielectric constant.