A method comprises applying a composition on a substrate to form a coating film on the substrate. The coating film is heated in an atmosphere in which an oxygen concentration is less than 1% by volume and a temperature is higher than 450° C. and 800° C. or lower, to form a film on the substrate. The composition comprises a compound comprising an aromatic ring. The oxygen concentration in the atmosphere during the heating of the coating film is preferably no greater than 0.1% by volume. The temperature in the atmosphere during the heating of the coating film is preferably 500° C. or higher and 600° C. or lower.