To provide a method for manufacturing a semiconductor device for achieving a clean machining interface and a semiconductor manufacturing device and at the same time a reliable method for manufacturing a semiconductor laser for suppressing optical damage and can reduce manufacturing cost in a process for performing ECR plasma etching and MOCVD growth continuously.

A wafer whose SiON film is subjected to patterning so that the oscillation end face part of laser can be opened is set to a preparation room 6 and is introduced to an ECR plasma etching chamber 7 through a wafer carrying room 10 in highly clean hydrogen atmosphere, thus forming the oscillation end face of laser. After etching is completed, nitriding treatment is successively performed and a surface nitriding layer 4 which becomes a protection layer is formed. After the nitriding treatment, the pressure in the ECR plasma etching chamber 7 is returned to atmospheric pressure by hydrogen purging and the wafer is introduced to a MOCVD chamber 8 through the wafer carrying room 10, thus performing the regrowth of AlGaAs layer 5 which is a window layer.