14 June 1999 Wafer printability simulation accuracy based on UV optical inspection images of reticle defects
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Abstract
As semiconductor processes have moved towards lower k1 and mask inspection equipment has moved into the UV range, more subtle reticle defects have been found to cause manufacturing problems. Lower k1 and new lithography processes and reticle technologies, such as OPC and PSM, have made it difficult to determine the significant and these defects. This paper reports on the development of a simulation tool that will improve the yield and productivity of photomask manufacturers and wafer manufacturers by improving reticle defect assessment. This study demonstrates the accuracy of simulation software that predicts resist patterns based on sophisticated modeling software that uses optical images obtained from a state-of-the-art UV optical inspection system. A DUV 4X reduction stepper was used to print a reticle with programmed defects across an exposure/focus matrix, with the minimum feature size being 200 nm. Quantitative comparisons between predicted and measured wafer CDs were made. In summary, it was found that the simulation software based solely on aerial images predicted absolute CDs with limited accuracy, but differential CDs with limited accuracy, but differential CDs, obtained by utilizing both the reference and defect images, were predicted accurately. Comparison of simulations using both reticle SEM images and optical reticle inspection images showed good agreement, demonstrating the accuracy and high resolution of the optical reticle inspection images. Application of differential aerial images to a simple test case showed that it was possible to identify and therefore eliminate a significant number of defects that did not print, thereby improving defect assessment.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Donald W. Pettibone, Donald W. Pettibone, Mohan Ananth, Mohan Ananth, Maciej W. Rudzinski, Maciej W. Rudzinski, Sterling G. Watson, Sterling G. Watson, Larry S. Zurbrick, Larry S. Zurbrick, Hua-Yu Liu, Hua-Yu Liu, Linard Karklin, Linard Karklin, } "Wafer printability simulation accuracy based on UV optical inspection images of reticle defects", Proc. SPIE 3677, Metrology, Inspection, and Process Control for Microlithography XIII, (14 June 1999); doi: 10.1117/12.350857; https://doi.org/10.1117/12.350857
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