Fast data acquisition in imaging ellipsometry using four-frame method

Won Chegal; Yong Jai Cho; Hyun Mo Cho; Yun Woo Lee; Soo Hyun Kim

doi:10.1117/12.576807

14 February 2005 Fast data acquisition in imaging ellipsometry using four-frame method

Won Chegal, Yong Jai Cho, Hyun Mo Cho, Yun Woo Lee, Soo Hyun Kim

Proceedings Volume 5634, Advanced Sensor Systems and Applications II; (2005) https://doi.org/10.1117/12.576807
Event: Photonics Asia, 2004, Beijing, China

Abstract

Ellipsometry is known as high precision metrology for thin film thickness measurements with sub-angstrom resolution. In ellipsometric measurements it does not measure film thickness or optical constants directly. It measures ellipsometric parameters, ψ and Δ, namely, defined as the ratio of reflection coefficients for p- and s-polarized light. Generally in rotating component ellipsometry, light intensity values at more than 256 angular positions of polarizer or analyzer with discrete Fourier transform methods are used to evaluate Fourier coefficients, which can be calculated to ellipsometric parameters explicitly. Using this scheme it is well suited in single point measuring ellipsometry, but it degrades measurement speed in imaging ellipsometry. In imaging ellipsometry due to the limitation in CCD detection speed, rotating components must move stepwisely, so more discrete positions of polarizer or analyzer takes more measurement time dramatically. So we propose four frame method which can be easily substituted for conventional discrete Fourier transform methods. Four frame method can save measurement time, but natively intensity measurements at only four angular positions can cause erroneous results in Fourier coefficients compared with that of discrete Fourier transform method. In the four frame method, many repetitive measurements for light intensity at each angular position can solve these shortcomings. That is, conceptually to reduce random noise in ellipsometric measurements, conventional discrete Fourier transform method uses spatial averaging technique, but four frame method uses temporal averaging technique. In our experiments we could get more than ten times fast measurements with four frame method.

Citation Download Citation

Won Chegal, Yong Jai Cho, Hyun Mo Cho, Yun Woo Lee, and Soo Hyun Kim "Fast data acquisition in imaging ellipsometry using four-frame method", Proc. SPIE 5634, Advanced Sensor Systems and Applications II, (14 February 2005); https://doi.org/10.1117/12.576807

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