A densified dielectric film is formed on a substrate by a process that
involves annealing a film deposited on the substrate by application of a
localized energy pulse, such as a laser pulse, for example one of about
10 to 100 ns in duration from an excimer laser, that raises the
temperature of the film above 1000.degree. C. without raising the
substrate temperature sufficiently to modify its properties (e.g., the
substrate temperature remains below 550.degree. C. or preferably in many
applications below 400.degree. C.). The dielectric deposition may be by
any suitable process, for example CVD, SOG (spin-on glass), ALD, or
catalyzed PDL. The resulting film is densified without detrimentally
impacting underlying substrate layers. The invention enables dielectric
gap fill and film densification at low temperature to the 45 nm
technology node and beyond, while maintaining oxide film properties.