Patent ID: 7964516

Claim:
A method for using a film formation apparatus for a semiconductor process, which includes a vertical process container configured to set a vacuum state therein, a holder configured to hold a plurality of productive target objects stacked at intervals inside the process container, a heating device disposed around the process container, a gas supply system configured to supply process gases into the process container, and an exhaust system configured to exhaust gas from inside the process container, the method comprising: repeating a film formation process a plurality of times respectively for a plurality of preceding batches of product target objects, the film formation process including alternately supplying a silicon source gas and a reactive gas containing oxygen or nitrogen into the process container accommodating the holder with each batch of productive target objects held thereon, and thereby forming a product film containing silicon and oxygen or nitrogen on the productive target objects; performing an intermediate operation including a cleaning process and a coating process performed in this order inside the process container after the number of repetitions of the film formation process reaches a predetermined number, such that the cleaning process includes supplying a cleaning gas containing a halogen or halogen compound into the process container to remove by-products films deposited by the film formation process from an inner wall of the process container and a surface of the holder with no productive target objects held thereon, and the coating process includes alternately supplying the silicon source gas and a nitriding gas into the process container to form a coating film consisting of a silicon nitride film for inhibiting metal contamination, which covers the inner wall of the process container and the surface of the holder with no productive target objects held thereon; and repeating the film formation process a plurality of times respectively for a plurality of subsequent batches of product target objects, after the intermediate operation, wherein the process container has a higher temperature area corresponding to the holder and a lower temperature area below the holder, and the coating process is arranged such that the coating film has a film thickness tH at the higher temperature area and a film thickness tL at the lower temperature area with a ratio tH/tL of 1 to 15, while the film thicknesses tH and tL fall in a range of 18 nm to 300 nm.