Patent ID: 9620402
Date: 2017-04-11
CPC Classifications: G05B,H01L

Claim:
1. An alignment apparatus for aligning a wafer that is a circular substrate in a predetermined orientation by optically detecting an alignment mark formed at a backside of the wafer by rotating a mounting unit on which the wafer is mounted, comprising: an imaging unit configured to image, from a position below the wafer, an imaging region having a strip shape extending in a diametrical direction of the wafer across a periphery of the wafer; an elevation unit configured to relatively move up and down the mounting unit or the imaging unit with respect to each other; a control unit configured to output a control signal for controlling the elevation unit such that a luminance variation between an outer side and an inner side of the wafer in a luminance distribution pattern in the diametrical direction of the wafer which is obtained by the imaging unit becomes a luminance variation obtained when the imaging unit is focused, for estimating a warpage state of the wafer based on an amount of relative movement of the imaging unit and the mounting unit with respect to a relative height position of the imaging unit and the mounting unit which is obtained when the imaging unit is focused on a reference wafer having no warpage, and for detecting the alignment mark of the wafer by the imaging unit by rotating the mounting unit in a state where the imaging unit is focused.