CVD method and apparatus therefor

A CVD apparatus comprising:

• a CVD reaction chamber,
• a circular-shaped heating stage for holding a substantially circular semiconductor wafer set thereupon at a predetermined temperature in said reaction chamber, said semiconductor wafer having opposing surfaces, each opposing surface including a peripheral surface, said circular-shaped heating stage having a specified diameter,
• an exhaust port surrounding said heating stage being outward of an edge of said wafer,
• a CVD reaction gas source and an inert gas source, said inert gas source supplying only inert gas,
• a gas head provided opposing said wafer for emitting gas towards said wafer, said gas head including a first gas blowing region in communication with said CVD reaction gas source for emitting CVD reaction gas towards at least a central major region of said wafer, said first gas blowing region being substantially circular in shape and having a diameter smaller than a diameter of said substantially circular semiconductor wafer, and a second gas blowing region in sole communication with said inert gas source, said second gas blowing region including an annular plate, the plate having gas blowing openings densely arranged therein, the second gas blowing region surrounding the periphery of said first gas blowing region and being sized with respect to the diameter of the wafer so that the gas blowing openings of said second gas blowing region perpendicularly face one of the peripheral surfaces of said wafer so that inert gas is directed to said one of the peripheral surfaces of the wafer, said first gas blowing region including a circular plate having gas blowing openings therein, the gas blowing openings densely arranged over substantially the entire circular plate such that said CVD reaction gas flows from said gas blowing openings toward said semiconductor wafer and radially outwardly toward said exhaust port, said first and second gas blowing openings being in a common plane apart from said wafer by a predetermined distance such that a face plane of the gas head is substantially parallel to a surface of the wafer and
• wherein the diameter of sad first gas blowing region is less than the diameter of said circular-shaped heading stage and said first gas blowing region is separated from the second gas blowing region by a thin wall,
• whereby a CVD film of high quality can be formed in uniform thickness of said wafer, and the consumed amount of reaction gas and the amount of the undesirable precipitated particles can be reduced.