8 June 1998 Defect inspection and linewidth measurement of SCALPEL thin membrane masks using optical transmission
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Abstract
The purpose of the study reported here was to determine the range of material parameters and optical conditions necessary for using light to identify and categorize defects and to measure linewidths in SCALPEL masks. A prototype 4X SCALPEL mask with a 150 nm SiNx membrane and 50/10 nm W/Cr scatterer was used for the measurements. Die to die defect inspections were performed using a KLA 300 Series mask inspection system with 488 nm light in transmission. There was sufficient contrast to detect defects within test features with critical dimensions as small as 0.72 micrometer which would make optical defect inspection feasible for the 0.18 micrometer generation of integrated circuit (IC) reticles. Linewidth measurements were performed with the KMS 310RT mask metrology system in transmission on features ranging from 1.04 to 0.32 micrometer and compared to scanning electron microscope (SEM) measurements. The optically measured linewidths were linear in the range 0.4 to 1.04 micrometer which would be suitable for 0.1 micrometer IC reticles. The optical properties of SCALPEL masks constructed with Si3N4 membranes were calculated as a function of wavelength and membrane thickness. The requirements for extending optical inspection capability to smaller feature sizes and other measurement modes are discussed.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Reginald C. Farrow, Myrtle I. Blakey, Richard J. Kasica, James Alexander Liddle, Masis M. Mkrtchyan, Anthony E. Novembre, Milton L. Peabody, Thomas E. Saunders, David L. Windt, Larry S. Zurbrick, James N. Wiley, Christopher M. Aquino, Steve L. Hentschel, Larry C. Davis, B. Boyer, "Defect inspection and linewidth measurement of SCALPEL thin membrane masks using optical transmission", Proc. SPIE 3332, Metrology, Inspection, and Process Control for Microlithography XII, (8 June 1998); doi: 10.1117/12.308730; https://doi.org/10.1117/12.308730
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