A method of filling a depression of a workpiece is provided. The depression passes through an insulating film and extends up to an inside of a semiconductor substrate. The method includes forming a first thin film made of a semiconductor material along a wall surface which defines the depression, performing gas phase doping on the first thin film, by annealing the workpiece within a vessel, forming an epitaxial region from the semiconductor material of the first thin film along a surface of the semiconductor substrate which defines the depression, without moving the first thin film with the gas phase doping performed, forming a second thin film made of a semiconductor material along the wall surface which defines the depression; and by annealing the workpiece within the vessel, further forming an epitaxial region from the semiconductor material of the second thin film moved toward a bottom of the depression.