Surface morphology and nucleation are important for forming electronic thin films on plastic substrates. We have used atomic force microscopy (AFM) with an oscillating cantilever to examine various transparent substrates, including 7059 glass, polyethylene terephthalate (PET), indium tin oxide (ITO)-coated PET, and polycarbonate, and studied the effect of deposition processes on these surfaces. Studies include: 1) differences in dielectric nucleation on plastics and glass; 2) dielectric growth evolution; and 3) the effect of plasma exposure on surface roughness. The surface morphology of the different substrate materials varied significantly with the PET showing the largest roughness values; all the polymers were more rough than typical 7059 glass (rms <0.5 nm). Furthermore, the initial nucleation on both polymers were different than on glass. Very thin layers (<30Å nominal thickness) of plasma deposited silicon nitride films on polycarbonate and glass produced flat, smooth surfaces, with rms roughness of ≈0.5 nm. On the PET substrates, the nitride growth began with broad, thin deposits and developed a coarse, large-grained structure as growth progressed. With exposure to a NH3 + N2 plasma, the glass and PET surfaces showed detectable changes in surface roughness, which are discussed below. These results demonstrate that plasma-deposited insulators nucleate and grow differently on plastic substrates than on glass, which has implications for electronic devices fabricated directly on plastics.