IMAGING OPTICS

Understanding chromatic aberration impacts on lithographic imaging

[+] Author Affiliations
Kafai Lai

IBM Microelectronics, Semiconductor Research and Development Center, East Fishkill, New York E-mail: kafailai@us.ibm.com

Ivan Lalovic

Cymer Inc., San Diego, California

Bob Fair

IBM Microelectronics, Semiconductor Research and Development Center, East Fishkill, New York

Armen Kroyan

Cymer Inc., San Diego, California

Christopher J. Progler

IBM Microelectronics, Semiconductor Research and Development Center, East Fishkill, New York

Nigel Farrar

Cymer Inc., San Diego, California

Dennis Ames

IBM Microelectronics, Semiconductor Research and Development Center, East Fishkill, New York

Khurshid Ahmed

Cymer Inc., San Diego, California

J. Micro/Nanolith. MEMS MOEMS. 2(2), 105-111 (Apr 01, 2003). doi:10.1117/1.1562929
History: Received Nov. 2, 2001; Revised Oct. 14, 2002; Accepted Nov. 4, 2002; Online April 11, 2003
Text Size: A A A

Recent development of high-precision aberration measurement techniques has enabled in situ characterization of the aberration response to wavelength offset. These measurements show that majority of the reconstructed Zernike terms exhibit some degree of sensitivity to wavelength. Although this dependence diminishes with the increasing order of Zernike polynomial, we consider the cumulative contribution of five Zernike terms, which have the strongest wavelength dependence (Z2,Z4,Z6,Z8,andZ11). The imaging impacts of KrF laser wavelength and spectral bandwidth are investigated using aerial image simulation; the behavior of the process window, mask error enhancement factor (MEEF), image placement, proximity effect, and sidelobe intensity is quantified. In this model, the chromatic aberrations are experimentally measured in a 0.68-NA KrF step-and-scan exposure system using the LITEL aberration test (InspecStep interferometer manufactured by LITEL Instruments, Inc., San Diego, California). The illumination spectrum input is characterized by spectroscopic measurement of a 2-KHz KrF laser source. In the lithography model, it is important to incorporate all of the wavelength-sensitive terms due to the additive contribution to the overall lens aberration balance. As shown previously, the longitudinal and lateral chromatic aberrations (image height and magnification) are the most sensitive to shift in center wavelength and have the strongest contribution to the aerial image modulation. Simulation results show several imaging changes for isolated lines and contact holes with changes in illumination spectrum. However, the rates of change are shown to decrease as bandwidth is reduced well into the subpicometer level. In the case of isolated contacts, the depth of focus (DOF) increases with the increase in bandwidth, however, at the expense of reduced exposure latitude. This suggests that engineering the spectral output of the laser can provide some process enhancement, although careful compromise is needed to utilize any DOF enhancement, since other image metrics including MEEF, side-lobe intensity, and image placement are also affected. © 2003 Society of Photo-Optical Instrumentation Engineers.

© 2003 Society of Photo-Optical Instrumentation Engineers

Citation

Kafai Lai ; Ivan Lalovic ; Bob Fair ; Armen Kroyan ; Christopher J. Progler, et al.
"Understanding chromatic aberration impacts on lithographic imaging", J. Micro/Nanolith. MEMS MOEMS. 2(2), 105-111 (Apr 01, 2003). ; http://dx.doi.org/10.1117/1.1562929


Tables

Access This Article
Sign in or Create a personal account to Buy this article ($20 for members, $25 for non-members).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Related Journal Articles

Related Proceedings Articles

Related Book Chapters

Topic Collections

Advertisement
  • Don't have an account?
  • Subscribe to the SPIE Digital Library
  • Create a FREE account to sign up for Digital Library content alerts and gain access to institutional subscriptions remotely.
Access This Article
Sign in or Create a personal account to Buy this article ($20 for members, $25 for non-members).
Access This Proceeding
Sign in or Create a personal account to Buy this article ($15 for members, $18 for non-members).
Access This Chapter

Access to SPIE eBooks is limited to subscribing institutions and is not available as part of a personal subscription. Print or electronic versions of individual SPIE books may be purchased via SPIE.org.