Modeling of bottom antireflection layers: sensitivity to optical constants

Ralph R. Dammel; Robert A. Norwood

doi:10.1117/12.241874

14 June 1996 Modeling of bottom antireflection layers: sensitivity to optical constants

Ralph R. Dammel, Robert A. Norwood

Proceedings Volume 2724, Advances in Resist Technology and Processing XIII; (1996) https://doi.org/10.1117/12.241874
Event: SPIE's 1996 International Symposium on Microlithography, 1996, Santa Clara, CA, United States

Abstract

Bottom anti-reflective layers provide a number of benefits including significant reduction in swing curve amplitude and reflective notching. The key to understanding how a bottom antireflective layer improves lithography lies in the interaction of the thin film system with the exposing radiation. Bottom antireflective layers function primarily via their absorption which is significantly larger than that of the overlying photoresist at the actinic wavelength. In the simplest physical picture, a bottom antireflective layer must be thick enough to effectively extinguish radiation that has passed through it twice, with the turning point being at the substrate/bottom antireflective layer interface. It might therefore seem that the larger the bottom antireflective layer absorption coefficient, the better the performance. More precise studies show that this simplistic view is incorrect. We have modeled the general photoresist/bottom antireflective layer/substrate film stack using the standard theory of thin film optics. It follows from the complete mathematical model that at very high absorption coefficients, bottom antireflective layers may act as mirror elements of their own. Reflection from the bottom antireflective layer/photoresist interface comes both from differences in the absorption coefficients of the two materials (the dominant effect), as well as from differences in the refractive indices. Theory therefore predicts an optimum set of optical constants for every desired film thickness range, a relationship which can be summarized in simple contour diagrams.

Citation Download Citation

Ralph R. Dammel and Robert A. Norwood "Modeling of bottom antireflection layers: sensitivity to optical constants", Proc. SPIE 2724, Advances in Resist Technology and Processing XIII, (14 June 1996); https://doi.org/10.1117/12.241874

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