The invention relates to a substrate processing device, and, more specifically, relates to a substrate processing device for carrying out the etching and evaporating of a substrate. The device comprises a cavity main body, the upper side of which is opened; a substrate supporting part which is disposed in the cavity main body and supports the substrate; a top plate which is dispsoed at the opening of the cavity main body to form a sealed processing cavity, wherein the bottom surface of the top plate is provided with a gas injection flow path; an auxiliary plate which is combined with the bottom surface of the top plate to form the gas injection flow path, and forms a plurality of gas diffusion holes so as to inject gas dowards through the gas injection flow path; an injection head part which is disposed at the lower side of the auxiliary plate, and forms a plurality of technological gas injection hole so as to inject technological gas towards a processing cavity. The injection head part is cleaned through the gas injected by the gas diffusion holes formed on the auxiliary plate, and enables the gas of the gas diffusion holes to be injected to the processing cavity.