Patent attributes
An alignment apparatus for aligning a wafer includes a mounting unit, an imaging unit, an elevation unit, and a controlling unit. The control unit outputs a control signal for controlling the elevation unit such that a luminance variation between the outer side and the inner side of the wafer obtained by the imaging unit becomes the same as 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 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.
