A method for controlling a
photolithography process includes providing a
wafer having a first
grating structure and a second
grating structure overlying the first
grating structure; illuminating at least a portion of the first and second grating structures with a
light source; measuring light reflected from the illuminated portion of the first and second grating structures to generate a reflection profile; determining an
overlay error between the first and second grating structures based on the reflection profile; and determining at least one parameter of an operating
recipe for a
photolithography stepper based on the determined
overlay error. A
processing line includes a
photolithography stepper, a first
metrology tool, and a controller. The photolithography
stepper is adapted to process wafers in accordance with an operating
recipe. The first
metrology tool is adapted to receive a
wafer having a first grating structure and a second grating structure overlying the first grating structure. The
metrology tool includes a
light source, a
detector, and a
data processing unit. The
light source is adapted to illuminate at least a portion of the first and second grating structures. The
detector is adapted to measure light reflected from the illuminated portion of the first and second grating structures to generate a reflection profile. The
data processing unit is adapted to determine an
overlay error between the first and second grating structures based on the reflection profile. The controller is adapted to determine at least one parameter of the operating
recipe of the photolithography stepper based on the determined overlay error.