Nanoscale x-ray imaging of circuit features without wafer etching

Junjing Deng, Young Pyo Hong, Si Chen, Youssef S. G. Nashed, Tom Peterka, Anthony J. F. Levi, John Damoulakis, Sayan Saha, Travis Eiles, and Chris Jacobsen
Phys. Rev. B 95, 104111 – Published 24 March 2017

Abstract

Modern integrated circuits (ICs) employ a myriad of materials organized at nanoscale dimensions, and certain critical tolerances must be met for them to function. To understand departures from intended functionality, it is essential to examine ICs as manufactured so as to adjust design rules ideally in a nondestructive way so that imaged structures can be correlated with electrical performance. Electron microscopes can do this on thin regions or on exposed surfaces, but the required processing alters or even destroys functionality. Microscopy with multi-keV x rays provides an alternative approach with greater penetration, but the spatial resolution of x-ray imaging lenses has not allowed one to see the required detail in the latest generation of ICs. X-ray ptychography provides a way to obtain images of ICs without lens-imposed resolution limits with past work delivering 20–40-nm resolution on thinned ICs. We describe a simple model for estimating the required exposure and use it to estimate the future potential for this technique. Here we show that this approach can be used to image circuit detail through an unprocessed 300μm-thick silicon wafer with sub-20-nm detail clearly resolved after mechanical polishing to 240μm thickness was used to eliminate image contrast caused by Si wafer surface scratches. By using continuous x-ray scanning, massively parallel computation, and a new generation of synchrotron light sources, this should enable entire nonetched ICs to be imaged to 10-nm resolution or better while maintaining their ability to function in electrical tests.

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  • Received 24 October 2016
  • Revised 10 January 2017

DOI:https://doi.org/10.1103/PhysRevB.95.104111

©2017 American Physical Society

Physics Subject Headings (PhySH)

  1. Techniques
Condensed Matter, Materials & Applied PhysicsAtomic, Molecular & OpticalGeneral Physics

Authors & Affiliations

Junjing Deng*

  • Applied Physics, Northwestern University, Evanston, Illinois 60208, USA

Young Pyo Hong

  • Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA

Si Chen

  • Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA

Youssef S. G. Nashed and Tom Peterka

  • Mathematics and Computing Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA

Anthony J. F. Levi

  • Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, USA

John Damoulakis

  • Advanced Electronics, Information Sciences Institute, University of Southern California, Marina del Rey, California 90292, USA

Sayan Saha and Travis Eiles

  • Intel Corporation, Hillsboro, Oregon 97124, USA

Chris Jacobsen

  • Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA; Applied Physics, Northwestern University, Evanston, Illinois 60208, USA; Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA; and Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, USA

  • *Present address: Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
  • Present address: Micro Encoder, Inc., Kirkland, Washington 98034, USA.
  • Corresponding author: c-jacobsen@northwestern.edu

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Issue

Vol. 95, Iss. 10 — 1 March 2017

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