Understanding focus effects in submicron optical lithography: Part 3--methods for depth-of-focus improvement

Chris A. Mack

doi:10.1117/12.130327

1 June 1992 Understanding focus effects in submicron optical lithography: Part 3--methods for depth-of-focus improvement

Chris A. Mack

Author Affiliations +

Proceedings Volume 1674, Optical/Laser Microlithography V; (1992) https://doi.org/10.1117/12.130327
Event: Microlithography '92, 1992, San Jose, CA, United States

Abstract

In general, depth-of-focus (DOF) decreases as the square of the feature size. As the resolution of optical lithography has improved, with the potential to go below 0.25 /tm, the decrease in usable DOF has been significant. As such, there has been increasing effort put towards ways of improving DOF in manufacturing. This paper will examine several proposed techniques for improving DOF including the use of geometry dependent mask bias, variable numerical aperture, multiple focal-plane exposures (the FLEX method), frequency plane spatial filtering, and annular illumination sources. As will be shown, each method offers the potential for improved DOF, but only for certain cases. None of the methods provides a general solution to the problem of shrinking focal depth, but rather they may simply slow the inevitable progression.

Citation Download Citation

Chris A. Mack "Understanding focus effects in submicron optical lithography: Part 3--methods for depth-of-focus improvement", Proc. SPIE 1674, Optical/Laser Microlithography V, (1 June 1992); https://doi.org/10.1117/12.130327

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