A method and system position a laser beam spot relative to a semiconductor
substrate having structures on or within the semiconductor substrate to
be selectively processed by delivering a processing laser beam to a
processing laser beam spot. The method generates a metrology laser beam
and propagates the metrology laser beam along a propagation path to a
metrology laser beam spot on or near a structure to be selectively
processed. The method detects a reflection of the metrology laser beam
from the structure, thereby generating a reflection signal, and
determining, based on the reflection signal, a position of the metrology
laser beam spot relative to the structure.