EUV mask characterization with actinic scatterometry

Stuart Sherwin; Andrew Neureuther; Patrick Naulleau

doi:10.1117/12.2501970

3 October 2018 EUV mask characterization with actinic scatterometry

Stuart Sherwin, Andrew Neureuther, Patrick Naulleau

Proceedings Volume 10809, International Conference on Extreme Ultraviolet Lithography 2018; 108090T (2018) https://doi.org/10.1117/12.2501970
Event: SPIE Photomask Technology + Extreme Ultraviolet Lithography, 2018, Monterey, California, United States

Abstract

With EUV Lithography rapidly approaching maturity, accurate metrology to thoroughly characterize EUV photomasks is needed. We present an actinic EUV reflection-based scatterometry technique to measure key parameters of EUV photomasks to characterize both the multilayer mirror substrate as well as periodic absorber targets fabricated on the multilayer. We show these measurements can be used both in determining the physical dimensions on the mask, and also in directly quantifying optical effects, which can provide invaluable feedback in the mask optimization and manufacturing processes. In this paper, we present four different methods of data analysis for EUV mask scatterometry: two for characterizing the multilayer mirror based on measurements of the reflected light intensity from a flat open area of the mask, and two more for characterizing absorber gratings fabricated on the multilayer substrate based on measurements of the diffraction efficiencies. Key findings include that a simple neural net architecture containing a single fullyconnected hidden layer that can characterize the multilayer’s angularly-varying complex reflection coefficient to 7 × 10^-4 accuracy, and that dictionary-based scatterometry with 7 wavelengths from 13.2 − 13.8nm can measure the absorber thickness of a grating to 0.4nm even in the presence of random and systematic errors. With the presented methods and findings, we hope to demonstrate that actinic EUV scatterometry has the capabilities to accurately characterize EUV masks in terms of both multilayer and absorber.

Conference Presentation

Citation Download Citation

Stuart Sherwin, Andrew Neureuther, and Patrick Naulleau "EUV mask characterization with actinic scatterometry", Proc. SPIE 10809, International Conference on Extreme Ultraviolet Lithography 2018, 108090T (3 October 2018); https://doi.org/10.1117/12.2501970

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available