title: Detecting 20 nm wide defects in large area nanopatterns using optical interferometric microscopy.
abstract: Due to the diffraction limited resolution and the presence of speckle noise, visible laser light is generally thought to be impractical for finding deep subwavelength defects in patterned semiconductor wafers. Here, we report on a nondestructive low-noise interferometric imaging method capable of detecting nanoscale defects within a wide field of view using visible light. The method uses a common-path laser interferometer and a combination of digital image processing techniques to produce 70 μm by 27 μm panoramic phase and amplitude images of the test nanopattern. Significant noise reduction and high sensitivity are achieved, which enables successful detection of several different types of sparse defects with sizes on the order of 20 nm wide by 100 nm long by 110 nm tall.
authors.affiliation: Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Renjie
authors.initials: R
authors.lastname: Zhou
authors.forename: Chris
authors.initials: C
authors.lastname: Edwards
authors.forename: Amir
authors.initials: A
authors.lastname: Arbabi
authors.forename: Gabriel
authors.initials: G
authors.lastname: Popescu
authors.forename: Lynford L
authors.initials: LL
authors.lastname: Goddard