Film forming method and plasma chemical vapor deposition apparatus

A plasma chemical vapor deposition apparatus for forming a diamond-like carbon film on a workpiece installed in a reactor by decomposing a hydrocarbon gas supplied into the reactor into plasma, the apparatus comprising:

• a high-frequency output device which outputs microwaves;
• and
• a waveguide member which extends to an inside of the reactor from an outside of the reactor, supports the workpiece with a portion of the waveguide member positioned in the reactor, and causes the microwaves output from the high-frequency output device to propagate to the workpiece, wherein
• the high-frequency output device outputs the microwaves having an intensity of higher than a first intensity and lower than a second intensity when a film is formed on the workpiece supported by the waveguide member,
• in a process of gradually increasing an intensity of the microwaves propagating to the workpiece through the waveguide member from “0”, the intensity of the microwaves output from the high-frequency output device when step-up of a bias current of the workpiece occurs is referred to as the first intensity, and
• in a process of gradually increasing the intensity of the microwaves from the first intensity, the intensity of the microwaves when step-up of the bias current of the workpiece occurs again is referred to as the second intensity.