NOVELTY - The method involves irradiating a surface of a substrate i.e. semiconductor wafer (W), with a high dielectric constant film formed on the substrate with flash of light from a flash lamp (FL) to heat the substrate surface and the film. The substrate is irradiated with the light from a halogen lamp (HL) to maintain the temperature of the substrate at another temperature lower than the former temperature in atmosphere, where the substrate temperature is maintained at the temperature in range of 300 degree to 700 degree Celsius for time period in range of 2 seconds to 30 minutes.    USE - Method for irradiating a substrate i.e. disk-shaped semiconductor wafer, with a high dielectric constant gate insulator film e.g. Titanium Nitrogen film, Zirconium Nitrogen film, Hafnium Nitrogen film, Vanadium Nitrogen film, Niobium Nitrogen film, Tantalum Nitrogen film, Molybdenum Nitrogen film, Tungsten Nitrogen film, Titanium Silicon Nitrogen film, Hafnium Silicon Nitrogen film, Vanadium Silicon Nitrogen film, Niobium Silicon Nitrogen film, Tantalum Silicon Nitrogen film, Molybdenum Silicon Nitrogen film, Tungsten Silicon Nitrogen film, Hafnium Aluminium Nitrogen film, Vanadium Indium film, Niobium Aluminum Nitrogen film, Tantalum Aluminum Nitrogen film, Molybdenum Aluminum Nitrogen film, and Tungsten Aluminum Nitrogen film, formed on the substrate with halogen/flash light to heat the substrate by using a heat treatment apparatus (all claimed) i.e. flash lamp annealer. Can also be used for irradiating a glass substrate in a flat panel display for an LCD apparatus or for a solar cell.    ADVANTAGE - The method enables effectively irradiating the substrate with the high dielectric constant film formed on the substrate with the light to heat the substrate by using the heat treatment apparatus to promote crystallization of the film by flash heating with low power consumption such that an annealing process is performed on the semiconductor wafer in an atmosphere of a hydrogen-nitrogen gas mixture using the halogen lamp, so that defects present near interfaces of the film are eliminated by hydrogen termination, thus improving interface characteristics of the film.    DETAILED DESCRIPTION - The atmosphere contains gas selected from a group consisting of hydrogen, ammonia, hydrogen chloride, sulthr dioxide, nitrous oxide, and hydrogen sulfide. An INDEPENDENT CLAIM is also included for a heat treatment apparatus for irradiating a substrate with a high dielectric constant film formed on the substrate with light to heat the substrate.    DESCRIPTION OF DRAWING(S) - The drawing shows a longitudinal sectional view of a heat treatment apparatus.    Flash lamp (FL)    Halogen lamp (HL)    Semiconductor wafer (W)    Gas supply opening (81)    Gas exhaust opening (86)    Exhaust part (190)    Gas exhaust pipe (191)