Anodizing method and apparatus and semiconductor substrate manufacturing method

摘要

A porous layer having a multilayered structure is formed. An Si substrate (102) to be processed is anodized in a first electrolytic solution (141, 151) while being held between an anode (106) and a cathode (104) in an anodizing bath (101). The first electrolytic solution (141, 151) is exchanged with a second electrolytic solution (142, 152). The Si substrate (102) is anodized again, thereby forming a porous layer having a multilayered structure on the Si substrate (102).