| CPC G03F 7/7085 (2013.01) [G03F 7/70508 (2013.01); G03F 7/70725 (2013.01); G03F 7/70775 (2013.01); G03F 7/70791 (2013.01)] | 19 Claims |

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1. A substrate processing apparatus, comprising:
a slab;
at least one guiderail coupled to and extending along the slab;
a first shuttle disposed on the at least one guiderail;
a second shuttle disposed on the first shuttle; and
a metrology bar coupled to a bottom of a chuck that is disposed on the second shuttle, wherein each distal end of the metrology bar extends laterally beyond a perimeter of the chuck, the metrology bar comprising:
at least one first sensor coupled to at least one distal end of the metrology bar; and
at least one second sensor laterally inward of the at least one first sensor.
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