PURPOSE: To obtain a ferroelectric film having improved film quality by depositing a film of a Pb-containing composition on a substrate and heating with a lamp at a prescribed temperature, thereby converting the deposited film to a perovskite crystal structure.

CONSTITUTION: A Pb-containing film 1 having a prescribed composition such as PZT (PbZrxTi1-xO3) is deposited on a substrate by sputtering process or a sol-gel process. Light is radiated exclusively to the film 1 on the substrate using a halogen lamp, etc., and the film is heated at 550-650°C for about 1min. The film is converted to a perovskite crystal structure to form a ferroelectric film 1'. A number of crystal nuclei 2 are formed in the film 1' by the quick- heating procedure and crystal grains 3 are grown on the nuclei. The crystal grains 3 are soon brought into contact with each other and the growth of the crystal is stopped while the crystal diameter is still small to get a ferroelectric film 1' containing crystal grains 3 having optimum diameters. In contrast with the above process, the crystal nuclei 12 in the film 11 are excessively grown in the case of heating with an electric furnace to get a heat-treated ferroelectric film 11' having too large crystal grains 13 to keep the film from cracking.