One subject of the invention is a process for the treatment of at least one thin continuous film deposited on a first side of a substrate, characterized in that said at least one thin film is raised to a temperature of at least 300° C. while maintaining a temperature not exceeding 150° C. on the opposite side of said substrate to said first side, so as to increase the degree of crystallization of said thin film while keeping it continuous and without a step of melting said thin film.Another subject of the invention is the material that can be obtained by this process.