Defect inspection and linewidth measurement of SCALPEL thin membrane masks using optical transmission

R. C. Farrow, M. I. Blakey, R. Kasica, J. A. Liddle, M. Mkrtchyan, A. Novembre, M. Peabody, T. Saunders, D. Windt, L. S. Zurbrick, J. N. Wiley, C. Aquino, S. L. Hentschel, L. C. Davis, B. Boyer

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


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 μm which would make optical defect inspection feasible for the 0.18 μm 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 μm and compared to scanning electron microscope (SEM) measurements. The optically measured linewidths were linear in the range 0.4 to 1.04 μm which would be suitable for 0.1 μm 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.

Original languageEnglish (US)
Pages (from-to)221-231
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 1998
Externally publishedYes
EventMetrology, Inspection, and Process Control for Microlithography XII - Santa Clara, CA, United States
Duration: Feb 23 1998Feb 25 1998

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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