Depression filling method and processing apparatus

A depression filling method for filling a depression of a workpiece including a semiconductor substrate and an insulating film formed on the semiconductor substrate, the depression penetrating the insulating film so as to extend to the semiconductor substrate, the method comprising:

• forming a thin film of a semiconductor material along a wall surface of the depression;
• annealing the workpiece at a temperature from 300 to 600 degrees C. and at a total pressure from 1×10−10 Torr to 1 Torr, to cause the semiconductor material of the thin film to move toward a bottom of the depression and to form an epitaxial region corresponding to crystals of the semiconductor substrate;
• and
• etching the thin film after annealing the workpiece,
• wherein an etching rate of the epitaxial region is lower than an etching rate of a remaining portion of the thin film,
• wherein the thin film is an amorphous semiconductor film and the semiconductor substrate is a monocrystalline semiconductor substrate or a polycrystalline semiconductor substrate,
• wherein the method further comprising forming a liner layer prior to forming the thin film,
• wherein the liner layer includes an amorphous semiconductor layer, which contains a first impurity,
• wherein the thin film is formed on the amorphous semiconductor layer, and
• wherein the thin film contains a second impurity and the first impurity of the amorphous semiconductor layer is higher in impurity concentration than the second impurity of the thin film.