Patent ID: 7176634

Claim:
A plasma generating method for generating a plasma in a treating chamber by controlling a high-frequency generating unit to generate a high-frequency signal and by feeding the high-frequency signal to the treating chamber through an impedance matching device, the plasma generating method comprising: controlling the high-frequency generating unit to generate and feed a high-frequency signal having a lower power than that generating plasma, to the treating chamber; measuring a reflectivity as a ratio of a reflected wave to a progressive wave between the high-frequency generating unit and the treating chamber in a state of feeding the high-frequency signal having the lower power than that generating plasma to the treating chamber; controlling the impedance matching device on the basis of at least the reflectivity measured to define a matching condition of the impedance matching device in which the reflectivity is not higher than a defined value, as a preset matching condition; controlling the impedance matching device, when the plasma is generated in the treating chamber, so as to satisfy the preset matching condition, and then controlling the high-frequency generating unit to generate and feed the high-frequency signal of the power generating the plasma, to the treating chamber.