Disclosed are a method for manufacturing a solar cell by processing a surface of a silicon substrate for a solar cell, a solar cell manufactured by the method, and a substrate processing system for performing the method. The method for manufacturing a solar cell comprises protrusion forming step including wet-etching process and for forming a plurality of minute protrusions on a light receiving surface of a crystalline silicon substrate, and planarization step of planarizing the bottom surface, the opposite surface to the light receiving surface of the substrate during or after the protrusion forming step.