Patent ID: 7727911

Claim:
A method for forming a gate insulating film of a high dielectric constant metal silicate on a semiconductor substrate, comprising the steps of: (a) with the semiconductor substrate being held at 500° C. or less and a predetermined pressure, exposing the semiconductor substrate to a first precursor containing a metal element of the high dielectric constant metal silicate to form a first adsorption layer of the first precursor on the semiconductor substrate; (b) purging the first precursor; (c) exposing the first adsorption layer to an oxidizing agent and thus oxidizing the first adsorption layer to form a metal oxide film from the first adsorption layer; (d) purging the oxidizing agent; (e) after the step (d), exposing the metal oxide film to a second precursor containing silicon to form a second adsorption layer of the second precursor on the metal oxide film; (f) purging the second precursor; (g) exposing the second adsorption layer to the oxidizing agent and thus oxidizing the second adsorption layer to form a silicon oxide film from the second adsorption layer; and (h) purging the oxidizing agent, wherein a cycle comprised of the steps (a), (b), (c), and (d) is performed at least once to form at least one layer of an atomic layer level of the metal oxide film, and a cycle comprised of the steps (e), (f), (g), and (h) is performed at least once to form at least one layer of an atomic layer level of the silicon oxide film, whereby the high dielectric constant metal silicate is formed, in the step (a), exposure time of the semiconductor substrate to the first precursor is determined by saturation time of a thickness of the one layer of the metal oxide film deposited by the cycle, in the step (c), exposure time of the first adsorption layer to the oxidizing agent is determined by time required for an oxygen content in the metal oxide film to reach 97% or more of a composition that is determined by stoichiometry, in the step (e), exposure time of the metal oxide film to the second precursor is determined by saturation time of a thickness of the one layer of the silicon oxide film deposited in the cycle, and in the step (g), exposure time of the second adsorption layer to the oxidizing agent is determined by time required for an oxygen content in the silicon oxide film to reach 97% or more of a composition that is determined by stoichiometry.