Effects of plasma treatments on structural and electrical properties of methyl-doped silicon oxide low dielectric constant film

In this article, a methyl-doped silicon oxide low k film for use in inter-level dielectric application has been characterized. The structural and electrical properties of films prepared by chemical vapor deposition before and after different etching and photo-resist stripping (PRS) plasma treatments were studied. Structural properties of the low k film with various extents of forming gas and O2 plasma treatments were reflected by the contents of Si–CH3 and Si–H bonds. Surface roughness of films with plasma treatments was closely linked to the ratios of the cage- and network-structures of Si–O. Electrical properties of plasma-treated films were dependent on the applications of both etching and PRS plasma chemistries. Forming gas PRS caused the least low k film structural change and electrical deterioration compared with O2 treatment. Moreover, Ebd of films decreased significantly by CH2F2 versus C4F8 etch. The best electrical properties of the film was obtained with a leakage current density of < 1 × 10− 8 A/cm2 and a dielectric breakdown strength of ∼3.2 MV/cm after being subjected with C4F8 / N2 / Ar trench etch and forming gas PRS treatment.