Patent ID: 7312584

Claim:
A plasma-generation power-supply device that drives a discharging load that generates a plasma, comprising: an alternating-current power-supply that supplies power to said discharging load; and a controller that is capable of controlling a frequency of an alternating output of said alternating-current power-supply, wherein said controller provides control to vary the power-supply frequency of said alternating-current power-supply in accordance with a target applied power to said discharging load, and said alternating-current power-supply is formed of an inverter, and said alternating output is a pulse output, and wherein when Cg: an electrostatic capacity value of a dielectric included in said discharging load, Ca: an electrostatic capacity value of a gas region included in said discharging load, Cp: a floating electrostatic capacity value in parallel with said discharging load, V*: a discharge maintaining voltage, L: an inductance value in a circuit including said discharging load, f: said power-supply frequency, and Cβ: an electrostatic capacity in a non-discharging state, then, said controller varies said power-supply frequency and a duty of said pulse output within a stable control region that is surrounded by: a characteristic curve of applied power that is obtained when said power-supply frequency is varied with said duty of said pulse output fixed at a maximum value; a curve representing 0.9 times a curve of an applied power Poz that is given by an expression below Poz = 4 ⁢ Cg ⁡ ( V * ) 2 ⁢ f ( Cg Cg + Cp - 1 L ⁡ ( 2 ⁢ π ⁢ ⁢ f ) 2 - ( 1 + Ca Cg ) ) ; and, a straight line representing a resonant frequency f max in the non-discharging state that is given by an expression for f max below f max = 1 2 ⁢ π ⁢ LC β .