Yield, metrology and inspection characteristics of SCALPEL masks

M. L. Peabody, M. I. Blakeya, Reginald Farrow, R. Kasica, J. A. Liddle, A. E. Novembre, T. Saundersa, D. M. Tennant, D. L. Windt

Research output: Contribution to journalConference articlepeer-review

2 Scopus citations

Abstract

SCALPEL (Scattering with Angular Limitation in Projection Electron Beam Lithography) masks have been fabricated for use in the SCALPEL Proof-of -Concept (SPOC) and the recently built SCALPEL Proof-of -Lithography (SPOL) tool. To date over 300 mask blanks have been formed and yield data as a function of the thickness of the silicon nitride membrane has been quantified. For thickness ranging from 100-1500 Å, the yield, defined as having all membranes and struts intact and flat (film is tensile), is in excess of 90%. The mask scatterer (W/Cr) film thickness investigated were 500Å/100Å and 250Å/50Å. Mask blanks, coated with 0.32 μm thick ZEP-520 resist, are patterned on a JEOL JBX6000FS e-beam exposure tool operating at 50 KeV. For the 500 Å thick W films, pattern transfer into the scatterer layer is accomplished using a SF6/O2 plasma etch process. Metrology on dry etched tungsten features have been obtained using an Hitachi 4160 SEM and indicates that CD linearity can be achieved over a 0.4-4.0 μm range. The SCALPEL tool prints at a 4X reduction, the above ranges corresponds to imaging 0.1-1.0 μm size features on the wafer. Additional mask metrology data has been obtained and a ̃1% difference is measured between equivalent size features present in an isolated and dense array and oriented in the horizontal and vertical direction. W line-edge roughness using the plasma etch process is ̃15 nm. Minimum contact hole geometries of 0.32 μm (0.08 μm at the wafer) and minimum isolated trenches of 0.24 μm (0.06 μm at the wafer) have been fabricated. SCALPEL masks have been inspected using a KLA SEMSpec in a die-to-die mode on features as small as 0.24 μm on the mask. For a patterned mask structure consisting of 500 Å W/100 Å Cr on 1500 Å SiNx, all defect types could be identified and no modifications to either the mask structure or SEMSpec operating conditions were required.

Original languageEnglish (US)
Pages (from-to)190-194
Number of pages5
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume3236
DOIs
StatePublished - Dec 1 1997
Event17th Annual BACUS Symposium on Photomask Technology and Management - Redwood City, CA, United States
Duration: Sep 17 1997Sep 17 1997

All Science Journal Classification (ASJC) codes

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

Keywords

  • Defect inspection
  • E-beam lithography
  • Mask metrology
  • Mask yield
  • Photomask
  • SCALPEL
  • SCALPEL mask

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