Patent ID: 11913776
Assignee: APPLIED MATERIALS, INC.
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 17:
18. A method, comprising:
determining a fixed beam angle ϑ0 of a light source and an initial orientation angle ϕinitial of a first zone of optical device structures of a substrate;
rotating the substrate to position the initial orientation angle ϕinitial perpendicular to a light path to be projected to the first zone of the substrate at the fixed beam angle ϑ0;
projecting the light path having a wavelength (λlaser) to the first zone of the substrate at the fixed beam angle ϑ0, the light path diffracting from the optical device structures to a beam splitter, the beam splitter directing a first portion of the light path to a first detector and a second portion of the light path to a second detector;
detecting a first image from the first portion of the light path with the first detector;
detecting a second image from the second portion of the light path with the second detector, wherein the second image is rotated to an angle different than the first image; and
measuring a reflected beam angle ϑreflected of the light path reflected by the substrate, the reflected beam angle ϑreflected derived from a center of a symmetric beam profile, the symmetric beam profile obtained by combining a first image and a second image of the light path reflected by the substrate, and wherein the second image rotated at a rotation angle different than the first image.