Film formation apparatus for semiconductor process and method for using the same

A method for using a film formation apparatus for a semiconductor process, the apparatus comprising:

• a process container having a vertically elongated process field configured to accommodate a plurality of target substrates,
• a support member configured to support the target substrates at intervals in a vertical direction inside the process field,
• a heater configured to heat the target substrates inside the process field,
• an exciting mechanism including a plasma generation area communicating with the process field and extending over a vertical length corresponding to the process field, with an electrode extending along the plasma generation area and configured to be supplied with an RF power for plasma generation, the plasma generation area being defined inside a cover attached on a sidewall of the process container with the electrode extending along an outside of the cover,
• a process gas supply system configured to selectively supply a silicon source gas, an ammonia gas, and an inactive gas into the process field, such that the silicon source gas is not supplied into the process field through the plasma generation area and the ammonia gas is supplied into the process field through the plasma generation area, and the silicon source gas and the ammonia gas are supplied to form essentially horizontal gas flows in the process field over a length corresponding to a vertical direction of the process field, and
• an exhaust system including an exhaust port disposed at a position facing the plasma generation area with the process field interposed therebetween and configured to exhaust gas from the process field, and
• the method comprising:
• performing a first CVD process, while supplying the silicon source gas and the ammonia gas into the process field, thereby forming a first silicon nitride film on first target substrates inside the process field, the first CVD process being a thermal CVD process performed by heating the silicon source gas and the ammonia gas by the heater without generating any plasma;
• unloading the first target substrates subjected to the first CVD process from the process container, and then performing a cleaning process of the plasma generation area and the process field;
• and
• then, performing a second CVD process, while supplying the silicon source gas and the ammonia gas into the process field, thereby forming a second silicon nitride film on second target substrates inside the process field, the second CVD process being a plasma CVD process performed by supplying the ammonia gas through the plasma generation area into the process field and generating plasma of the ammonia gas by the exciting mechanism while setting the RF power supplied to the electrode at a predetermined film formation electrical energy,
• wherein the cleaning process comprises:
• intermittently supplying the ammonia gas pulsewise through the plasma generation area into the process field and supplying a first part of the inactive gas through the plasma generation area into the process field continuously along with or pulsewise alternately with the ammonia gas intermittently supplied, while continuously supplying a second part of the inactive gas into the process field, not through the plasma generation area, and while exhausting gas from the process field, and
• applying the RF power to the electrode pulsewise to turn on the exciting mechanism in synchronism with the ammonia gas intermittently supplied to thereby cause plasma ignition impacts while the RF power is set at a cleaning electrical energy, which is 120 to 500% of the film formation electrical energy so as to intermittently generate plasma of the ammonia gas pulsewise a plurality of times, the impact of the plasma ignition peeling off by-product films deposited on an inner wall of the cover where the plasma generation area is located.