Fast evaluation of photomask near-fields in subwavelength 193-nm lithography

Jaione Tirapu-Azpiroz; Eli Yablonovitch

doi:10.1117/12.544236

28 May 2004 Fast evaluation of photomask near-fields in subwavelength 193-nm lithography

Jaione Tirapu-Azpiroz, Eli Yablonovitch

Proceedings Volume 5377, Optical Microlithography XVII; (2004) https://doi.org/10.1117/12.544236
Event: Microlithography 2004, 2004, Santa Clara, California, United States

Abstract

Sub-wavelength lithography places a serious limitation on the conventional "thin mask" approximation of the field immediately behind the patterned mask. This approximation fails to account for the increasingly important topographical effects of the mask or "thick mask" effects. This approximation of the photomask near-fields results from the direct application of Kirchhoff Boundary Conditions, which multiply the incident field by a binary transmission function of the patterned mask. Polarization dependent edge diffraction effects, as well as phase and amplitude transmission errors that arise from the vector nature of light, and the finite thickness of the substrate and chrome layers, produce significant errors in the scalar simulations of the lithographic image. Based on the comparison of aerial images at the wafer plane produced by both rigorous electromagnetic solutions of the field on the mask and their "thin mask" counterparts, a more accurate model is proposed that consists of a fixed-width, locally-determined boundary layer of imaginary transmission coefficient added to every edge of the initial "thin mask" approximation. The accuracy of the resultant Boundary Layer model has been exhaustively tested against rigorously simulated aerial images of isolated as well as periodic features of very different profiles and dimensions. The conclusion being that this simple approach is capable of modeling "thick mask" effects at both 248nm and 193nm wavelength and high NA lithography. This greatly improves the accuracy of aerial image computation in photolithography simulations at a reasonable computational cost.

Citation Download Citation

Jaione Tirapu-Azpiroz and Eli Yablonovitch "Fast evaluation of photomask near-fields in subwavelength 193-nm lithography", Proc. SPIE 5377, Optical Microlithography XVII, (28 May 2004); https://doi.org/10.1117/12.544236

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