Wafer-mapping load post interface having an effector position sensing device

A wafer-handling interface adapted for mating with and engaging a pod, the pod providing a plurality of slots within the pod which adapt the pod to receive and carry a plurality of disk-shaped objects arranged as a stack with planar surfaces of the disk-shaped objects disposed substantially parallel;

• the wafer-handling interface comprising:
• a table adapted for receiving the pod;
• an effector adapted for movement along an axis past edges of the stacked disk-shaped objects disposed within the pod when the pod is received upon the table;
• a drive-mechanism that upon activation moves said effector along the axis past edges of the stacked disk-shaped objects;
• position-sensing means that provides coordinate data indicating locations of the effector as said drive-mechanism moves the effector along the axis past edges of the stacked disk-shaped objects;
• a sensor secured to said effector that detects edges of the disk-shaped objects as said effector moves along the stack, and in response to the sensing thereof transmits an edge-detection signal;
• and
• wafer-locating means that receives the coordinate data from said position-sensing means and the edge-detection signal from said sensor, said wafer-locating means using the received coordinate data and edge-detection signal to determine when:
• a) a single disk-shaped object occupies a particular slot in the pod;
• b) a disk-shaped object crosses a slot within the pod thereby the disk-shaped object has a segment of the edge thereof disposed in a first slot and a diametrically opposite segment of the edge thereof disposed in a second slot that is immediately adjacent to the first slot;
• and
• c) a single slot holds two disk-shaped objects.