Now the wafer is transferred to microphotography apparatus. The wafer is placed on a stage located beneath a mask holder and a rotatable turntable. On the turntable a microscope and a light source are mounted.
To load the wafer, the mask holder must be pivoted upward and the wafer slid beneath. The wafer will again be held by a vacuum chuck. It must be placed so that the wafer edge is just inside the 4" (100 mm) groove on the chuck. The wafer holder can be moved vertically or horizontally, as well as rotated, by using the alignment screws.
