METHOD AND APPARATUS FOR PEELING NITRIDE FILM BY LOCOS METHOD

PURPOSE:To suppress reduction in moisture concentration in phosphoric acid solution and to uniformly etch the thickness of a nitride film in a predetermined dipping time by covering phosphoric acid solution surface with a high moisture atmosphere. CONSTITUTION:A gas annular tube 4 and a pure water annular tube 5 are provided above the surface of a phosphoric acid solution 2 along its inner surface in a liquid tank 1, gas such as the air, nitrogen gas and superpure water are supplied from a gas supply tube 6 and a pure water supply tube 7. On the other hand, atomizing nozzles 8 are mounted at a predetermined interval in the tube 5. The nozzles 8 are formed by concentrically inserting gas nozzles 9 provided at the tube 4, and superpure water in the tube 5 is atomized to be injected in a principle of atomizing by the injection force of the gas injected from the nozzles 9. Thus, when the nitride film of an Si substrate is etched in the tank 1, even if the solution 2 is heated, moisture concentration is not varied.