Low dielectric constant materials are ideal for use as interconnect dielectrics for integrated circuits (ICs) and multichip modules as they reduce power dissipation, crosstalk, and signal propagation delays. For high performance and reliability of ICs, reduced thermal and intrinsic stress is highly desirable. Low thermal budget rapid isothermal processing can provide materials with lower stress. In this paper, we demonstrate the role of photoeffects in the curing of polyimide films using a rapid isothermal processor with different lamp configurations. Each configuration provided a different photon spectrum on the surface of the polyimide films. The availability of large numbers of ultraviolet and vacuum ultraviolet photons on the film surface allowed a lower curing temperature and also resulted in the lowest film stress. We demonstrate a direct one-to-one correlation between electrical, mechanical, and structural properties of the organic dielectrics.