Method of depositing silicon nitride film, apparatus for depositing film, and silicon nitride film

A method of depositing a silicon nitride film, comprising:

• disposing, inside a vacuum chamber, a silicon target and a to-be-deposited object in a positional relationship to face each other;
• introducing a sputtering gas, containing therein nitrogen gas, into the vacuum chamber in a vacuum atmosphere;
• applying a negative potential to the silicon target such that the silicon nitride film having a tensile stress is deposited in a reactive sputtering on a surface of the to-be-deposited object that is placed in an electrically floated state;
• wherein the method further comprises:
• making the to-be-deposited object to a state in which a bias potential is free from being applied thereto;
• and
• controlling at least one of a flow ratio of the nitrogen gas to the sputtering gas and the potential to be applied to the silicon target such that the surface of the silicon target can be maintained in a transition mode between a metallic mode and a compound mode, thereby depositing β-silicon nitride on the surface of the to-be-deposited object.