NOVELTY - Substrate treatment method for treating a substrate involves performing a first phosphoric acid treatment step of causing a substrate holding unit to hold the substrate and supplying a phosphoric acid aqueous solution to the substrate to treat the substrate with the first concentration phosphoric acid aqueous solution for the removal of the first silicon nitride film, and second phosphoric acid treatment step of supplying a phosphoric acid aqueous solution to the substrate to treat the substrate for removal of the silicon oxide film.    USE - The substrate treatment method and apparatus are useful for treating a substrate with a treatment liquid (all claimed). The substrate to be treated includes semiconductor wafers, glass substrates for liquid crystal display devices, substrates for plasma display devices, substrates for FED (Field Emission Display) devices, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photo masks, ceramic substrates and substrates for solar cells.    ADVANTAGE - The method treats substrate in less time. The apparatus prevents the first liquid and the second liquid from flowing out into the gas outlet line is provided in the inner space.    DETAILED DESCRIPTION - Substrate treatment method for treating a substrate including a first silicon nitride film provided on a front surface and a silicon oxide film provided on the first silicon nitride film to remove the first silicon nitride film and the silicon oxide film from the substrate, involves performing a first phosphoric acid treatment step of causing a substrate holding unit to hold the substrate and supplying a phosphoric acid aqueous solution having a predetermined first concentration to the substrate held by the substrate holding unit to treat the substrate with the first concentration phosphoric acid aqueous solution for the removal of the first silicon nitride film, and second phosphoric acid treatment step of supplying a phosphoric acid aqueous solution having a second concentration lower than the first concentration to the substrate to treat the substrate with the second concentration phosphoric acid aqueous solution for the removal of the silicon oxide film after the first phosphoric acid treatment step. An INDEPENDENT CLAIM is included for substrate treatment apparatus for treating a substrate including a first silicon nitride film provided on a front surface thereof and a silicon oxide film provided on the first silicon nitride film to remove the first silicon nitride film and the silicon oxide film from the substrate.