SEMICONDUCTOR DEVICE MANUFACTURING METHOD, SUBSTRATE PROCESSING APPARATUS AND SUBSTRATE PROCESSING METHOD

PROBLEM TO BE SOLVED: To provide a semiconductor device manufacturing method and a substrate processing apparatus which can inhibit contamination caused by alkaline metal of a substrate such as Na.SOLUTION: A semiconductor device manufacturing method comprises: a first plasma production process of causing a plasma production part to produce a mixed plasma of oxygen and hydrogen in a state where there is no substrate in a processing chamber; and a second plasma production process of causing the plasma production part after the first plasma production process to produce a mixed plasma of hydrogen and nitrogen in a state where there is a substrate in the processing chamber.