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Purnima Balakrishnan (Fed)

Physical Scientist

Purnima Balakrishnan is a physicist at the National Institute of Standards and Technology (NIST), focused on characterization of thin film materials and nanostructures.

She is currently working at the Synchrotron Ultraviolet Radiation Facility (SURF III) on the development of a full Mueller Matrix spectroscopic ellipsometer in the VUV/EUV wavelength range. This instrument is under development as part of the EUV Scatterometry project under the CHIPS Metrology Program, with the goal of increasing sensitivity to features of increasing complexity in the manufacturing of semiconductor chips by realizing spectroscopic ellipsometry at shorter wavelengths.

Purnima was previously an NRC postdoc at the NIST Center for Neutron Research (NCNR) on the neutron reflectometry team, where she used neutron, x-ray, and muon scattering and spectroscopy techniques to study magnetic properties of quantum materials at surfaces and interfaces; the interplay between topology, magnetism, and superconductivity; and electrical and ionic control of magnetism in solid-state devices. She helped commission CANDOR, the newest neutron reflectometer at NCNR, contributed to the reflectometry analysis software Refl1d, and designed and ran experiments at the NCNR and many other user facilities, nationally and internationally.

Awards

2022 PEAR Technical Accolade for outstanding leadership enabling continued support of user science during the NCNR outage

Publications

Harnessing the extreme ultraviolet for critical dimension metrology

Author(s)
Bryan Barnes, Purnima P. Balakrishnan, John Burnett, Aaron Chew, Colton Dudley, Thomas Germer, Steven Grantham, Stephanie Moffitt, Eric Shirley, Martin Sohn, Daniel Sunday
The semiconductor industry has long adopted visible and ultraviolet wavelengths for optical critical dimension (OCD) measurements. Decreasing feature sizes...

Lab-based multi-wavelength EUV diffractometry for critical dimension metrology

Author(s)
Bryan Barnes, Aaron Chew, Nicholas Jenkins, Yunzhe Shao, Martin Sohn, Regis Kline, Daniel Sunday, Purnima Balakrishnan, Thomas Germer, Steven Grantham, Clay Klein, Stephanie Moffitt, Eric Shirley, Henry Kapteyn, MARGARET MURNANE
Background: The industry is developing extreme-ultraviolet wavelength (EUV) techniques to measure critical dimensions (CDs) in logic fabrication. As nascent...

Data and Software Publications

Lab-based multi-wavelength EUV diffractometry for critical dimension metrology

Author(s)
Bryan M Barnes, Aaron Chew, Nicholas W Jenkins, Yunzhe Shao, Martin Y Sohn, R Joseph Kline, Daniel F Sunday, Purnima P Balakrishnan, Thomas A Germer, Steven E Grantham, Clay Klein, Stephanie L Moffitt, Eric A Shirley, Henry C Kapteyn, Margaret M Murnane
This data set provides the measurement data from EUV diffractometry, simulated fits to these data, and parametric values and uncertainties from these fits as first reported in Barnes et al., "Lab
Created December 8, 2019, Updated September 16, 2026
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