Patent ID: 6045862
Filing Date: 2000-04-04
Classification: C23C

Abstract:
A CVD film forming method, wherein an object to be processed is mounted on a susceptor provided in a process chamber and a process gas is supplied to a main surface of the object to be processed, thereby forming a film on the object to be processed, said method comprising a step of supplying film formation preventing gas in a direction from a rear surface of the object to be processed toward a peripheral edge thereof, the film formation preventing gas having a flow rate which prevents the process gas from flowing to the rear surface of the object to be processed at the peripheral edge of the object to be processed, wherein the object to be processed is mounted on the susceptor so as to have a projected portion, in the peripheral portion of the object to be processed, which is projected from the susceptor, and a passage through which the film formation preventing gas flows toward the peripheral edge of the object to be processed is formed between a ring-shaped member and the object to be processed from a rear surface of the projected portion of the object to be processed, wherein, the ring-shaped member has an inner flange portion on an inner circumferential surface thereof, the inner flange portion having a surface opposing with a predetermined gap to the rear surface of the object to be processed mounted on the susceptor in the projected portion, thus defining a first part of the passage between the surface of the inner flange portion and the rear surface of the object to be processed, and where a length of the first part of the passage is represented by L (m), a diffusion constant of the process gas is D (m.sup.2 /s) and a flow rate of the film formation preventing gas is represented by v (m/s), and the length L and the flow rate v are set to satisfy a condition of Lv/D>1.