Patent ID: 8414355

Claim:
A substrate processing apparatus comprising: a polishing unit configured to polish a periphery of a substrate; an imaging module configured to take an image of the periphery of the substrate polished by said polishing unit; an image processing section configured to inspect a polished state of the substrate based on the image taken by said imaging module; and a polishing-condition determining section configured to determine a polishing condition in said polishing unit; wherein said imaging module is configured to take the image of the periphery of the substrate from multiple directions when said polishing unit is not polishing the periphery of the substrate; wherein said imaging module includes prisms to be disposed adjacent to the periphery of the substrate and an imaging camera for taking the image of the periphery of the substrate through said prisms; wherein said prisms are configured to adjust a second optical path length between an upper portion of the periphery of the substrate and said imaging camera, and to adjust a third optical path length between a lower portion of the periphery of the substrate and said imaging camera such that the second optical path length and the third optical path length are equal to a first optical path length between a middle portion of the periphery of the substrate and said imaging camera; wherein said imaging camera is arranged to take the image of the middle portion of the periphery directly without said prisms and to take the image of the upper portion of the periphery and the image of the lower portion of the periphery through said prisms; wherein an inspection result of said image processing section is transmitted to said polishing-condition determining section; and wherein said polishing-condition determining section is configured to determine the polishing condition in said polishing unit based on the inspection result.