Photosensitive polyimide (PSPI) is being integrated as potential low dielectric constant layers in next generation advanced silver metallization. These dielectrics have excellent thermal stability as represented by a thermal decomposition temperature of 450 degreesC and an average thermal expansion coefficient of 20 x 10(-6)/degreesC. This results in a low stress (< 26 MPa) in the polyimide film as measured during in situ curing and cooling cycles. The morphology and structure of two types of polyimides, 3,3 ' ,4,4 ' -biphenyl tetracarboxylic acid dianhydride-p-phenylenediamine (BPDA/PPD) and the PSPI based on BPDA/PPD, have been investigated in this work. Both refractive indices measurements and x-ray scans indicated that the 85 degreesC dried BPDA/PPD is slightly anisotropic, but the dried PSPI films are isotropic. Both polyimide films cured at 300 degreesC exhibit optical anisotropy with the average in-plane refractive index of 1.74 and the out-of-plane index of 1.62, indicating a strong preference of polymer chains to orient along the film plane. The dielectric constants were 3.0 and 2.6 in the in-plane and out-of-plane directions, respectively. The reduced number of process steps associated with PSPI and Ag etch over conventional Cu chemical mechanical polishing, shows great potential in terms of future process integration.