- shows 3 test options
- check if a wafer is located at the expected position
- by using TIS 1,2,3,4 sensor, it can figure out wafers position
- possible results :
- rotate clock wise, count clock wise
- shift E,S,S,N
- How to read result
- blue line : defalt distance between each TIS and align mark
- red line : real reading value
- check wafer is parlelly located
- normal value is 0
- wafers always should be super clean, check if wafers are contaminated
- color show how wafers contaminated