Optimal measurement method for scatterometer-based overlay metrology

Yi-Sha Ku; Weite Hsu; Sen-Yih Chou; Deh-Ming Shyu

doi:10.1117/1.2969120

1 August 2008 Optimal measurement method for scatterometer-based overlay metrology

Yi-Sha Ku, Weite Hsu, Sen-Yih Chou, Deh-Ming Shyu

Author Affiliations +

Optical Engineering, Vol. 47, Issue 8, 083604 (August 2008). https://doi.org/10.1117/1.2969120

Abstract

Scatterometry takes advantage of the sensitivity exhibited by optical diffraction from periodic structures, and hence is an efficient technique for lithographic process monitoring. Even though the potential of this technique has been known for many years, it is challenging to accurately and quickly extract the multilayer grating overlay from diffraction data. We propose a method to measure the overlay by selecting an optimal measurement design based on the theoretical modeling of differential signal scatterometry overlays. A set of two grating overlay targets are designed with an intentional offset difference between the top and bottom gratings, to maximize the differential signal measurement sensitivity and to minimize the response to the process noise. We model the measurement sensitivity to overlays of two layer gratings, at a fixed wavelength and with a range of azimuth incidence angles from 0 to 180 deg, by means of rigorous diffraction theory. We compare the optical response of the zero- and first-order diffractive overlays. We show that with the appropriate target design and algorithms, scatterometry overlay achieves improved accuracy for future technology nodes.

©(2008) Society of Photo-Optical Instrumentation Engineers (SPIE)

Citation Download Citation

Yi-Sha Ku, Weite Hsu, Sen-Yih Chou, and Deh-Ming Shyu "Optimal measurement method for scatterometer-based overlay metrology," Optical Engineering 47(8), 083604 (1 August 2008). https://doi.org/10.1117/1.2969120

Published: 1 August 2008

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