Wafer Types
The Wafer Pre-Align tool can locate three types of wafers: round wafers, wafers with an alignment flat (flat wafers), and wafers with an alignment notch (notched wafers). The figure below shows the appearance of each type of wafer.
The Wafer Pre-Align tool can determine the location of all of these wafer types; the tool can determine the orientation only of flat and notched wafers.