Yield, metrology, and inspection characteristics of SCALPEL masks

Milton L. Peabody Jr.; Myrtle I. Blakey; Reginald C. Farrow; Richard J. Kasica; James Alexander Liddle; Anthony E. Novembre; Thomas E. Saunders; Donald M. Tennant; David L. Windt

doi:10.1117/12.301190

12 February 1997 Yield, metrology, and inspection characteristics of SCALPEL masks

Milton L. Peabody Jr., Myrtle I. Blakey, Reginald C. Farrow, Richard J. Kasica, James Alexander Liddle, Anthony E. Novembre, Thomas E. Saunders, Donald M. Tennant, David L. Windt

Author Affiliations +

Proceedings Volume 3236, 17th Annual BACUS Symposium on Photomask Technology and Management; (1997) https://doi.org/10.1117/12.301190
Event: 17th Annual BACUS Photomask Technology and Management, 1997, Redwood City, CA, United States

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 angstrom, 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 500 angstrom/100 angstrom and 250 angstrom/50 angstrom. Mask blanks, coated with 0.32 micrometer thick ZEP-520 resist, are patterned on a JEOL JBX6000FS e-beam exposure tool operating at 50 KeV. For the 500 angstrom 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 micrometer range. The SCALPEL tool prints at a 4X reduction, the above ranges corresponds to imaging 0.1 - 1.0 micrometer size features on the wafer. Additional mask metrology data has been obtained and an approximately 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 approximately 15 nm. Minimum contact hole geometries of 0.32 micrometer (0.08 micrometer at the wafer) and minimum isolated trenches of 0.24 micrometer (0.06 micrometer 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 micrometer on the mask. For a patterned mask structure consisting of 500 angstrom W/100 angstrom Cr on 1500 Angstrom SiN_x, all defect types could be identified and no modifications to either the mask structure or SEMSpec operating conditions were required.

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Milton L. Peabody Jr., Myrtle I. Blakey, Reginald C. Farrow, Richard J. Kasica, James Alexander Liddle, Anthony E. Novembre, Thomas E. Saunders, Donald M. Tennant, and David L. Windt "Yield, metrology, and inspection characteristics of SCALPEL masks", Proc. SPIE 3236, 17th Annual BACUS Symposium on Photomask Technology and Management, (12 February 1997); https://doi.org/10.1117/12.301190

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