Open AccessEvidence of speckle in extreme-UV lithography
Author(s) -
Alessandro Vaglio Pret,
Roel Gronheid,
Jan Engelen,
Pei–yang Yan,
Michael J. Leeson,
Todd R. Younkin
Publication year - 2012
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.20.025970
Subject(s) - speckle pattern , optics , photoresist , lithography , extreme ultraviolet lithography , materials science , surface roughness , photolithography , surface finish , resist , wavelength , spatial frequency , optoelectronics , physics , nanotechnology , layer (electronics) , composite material
Based on reflective optics at 13.5 nm, extreme-UV lithography is the ultimate top-down technique to define structures below 22 nm but faces several challenges arising from the discrete nature of light and matter. Owing to the short wavelength, mask surface roughness plays a fundamental role in the increase of speckle pattern contrast, compromising the uniformity of the printed features. Herein, we have used a mask with engineered gradient surface roughness to illustrate the impact that speckle has on the resulting photoresist pattern. The speckle increases the photoresist roughness, but surprisingly, only when the mask surface roughness is well above existing manufacturing capabilities.