Edge portion measuring apparatus and method for measuring edge portion

An edge portion measuring apparatus for measuring shape of an edge portion of a wafer, comprising:

• a holding portion that holds the wafer;
• a rotating means for rotating the wafer by rotating the holding portion;
• and
• a sensor which comprises a light projecting portion for projecting a laser light from a light source onto the edge portion of the wafer held by the holding portion, and a light receiving detection unit that receives diffuse reflected light that the laser light projected from the light projecting portion is reflected at the edge portion of the wafer, wherein
• the rotating means is configured to rotate the wafer while the wafer is held by the holding portion, the wafer being in subjected to a slicing process, a chamfering process, a lapping/grinding process, or an etching process,
• the sensor is configured to project the laser light and receive the diffuse reflected light at least in a range from a normal direction of a held surface of the wafer to a normal direction of a surface opposite to the held surface, and
• the edge portion measuring apparatus is configured to measure the shape of an entire area of the edge portion of the wafer by a triangulation method in which an amount of movement of a measurement point with respect to the sensor is measured from an amount of change in an imaging position of the diffuse reflected light received by the sensor.