Substrate processing device, method for manufacturing semiconductor device, and program

Provided is a technical configuration comprising a reaction chamber for processing a substrate, a microwave oscillator for supplying a microwave to a processing chamber, and a control unit configured to be able to control the microwave oscillator so as to perform: a heating process in which the microwave, while being maintained at a first microwave output, is supplied to the substrate to heat the same by repeating, a predetermined number of times or for a first predetermined time, a supply time for supplying a first microwave and a stopping time shorter than the supply time for stopping the first microwave; and a reforming process in which the microwave, while being maintained at a second microwave output higher than the first microwave output, is supplied to the substrate for a second predetermined time to reform the same.