The invention provides a method of epitaxial structure formation in a semiconductor, comprising: providing a substrate; performing a dry etch to form a first recess; after performing the dry etch, performing a SPM cleaning process on the substrate by using a nozzle spraying SPM solution with an angle greater than zero and less than 45 degrees relative to the substrate; after performing the SPM cleaning process, performing a wet etch to form a second recess; after performing the wet etch, performing a pre-epi cleaning process; and growing an epitaxial structure in the second recess.