FILM-FORMING APPARATUS, MATCHING UNIT, AND IMPEDANCE CONTROL METHOD

摘要

Impedance control is realized to avoid vanishment of a plasma because of a sudden variation of the load impedance which may occur immediately after a plasma is fired. A film-forming apparatus comprises a high-frequency power supply, a matching circuit, an external electrode which receives power from the high-frequency power supply through the matching circuit and produces a plasma with the power within a film-forming chamber containing a resin bottle on which a film is to be formed, and a control section for controlling the impedance of the matching circuit. The control section maintains the impedance of the matching circuit at a constant value for a first period from a first time t₁ at which the high-frequency power supply starts to supply the power to the external electrode and controls the impedance of the matching circuit in response to the reflected wave power from the external electrode for a second period from a second time t₂ at which the first period ends.