Apparatus for forming thin film and method of manufacturing semiconductor film

An apparatus for forming a thin film, comprising:

• a vacuum chamber including a substrate holding unit that holds a substrate and a plasma electrode that is provided so as to face the substrate;
• a first gas supply unit that continuously supplies a gas containing hydrogen as a main component to the vacuum chamber during deposition;
• a second gas supply unit that opens or closes a valve to turn on or off the supply of a material gas containing at least one of silicon and germanium to the vacuum chamber during deposition;
• a high-frequency power source that applies a high frequency voltage to the plasma electrode;
• a shield box that is connected to a ground so as to surround the plasma electrode outside the vacuum chamber;
• and
• a control unit that controls opening or closing of the valve such that the material gas is periodically supplied to the vacuum chamber, and modulates an amplitude of high frequency power supplied to the plasma electrode in synchronization with the opening or closing of the valve,
• wherein the valve is provided in the shield box.