edfas.org ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 25 NO. 4 34 SUMMARY This article described the workings of a SEM system as it pertains to measuring voltage contrast from DUT surfaces. Waveforms and signals up to 2 GHz can be analyzed presently, while a roadmap to a 6 GHz system is feasible, with development well underway. With the incredible resolution achieved by SEM imaging and the numerous applications enabled by charged-particle microscopy besides just the voltage-contrast applications described herein, SEM systems are becoming indispensable for modern IC characterization and debug applications. REFERENCES 1. Y. Lin and D.C. Joy: “A New Examination of Secondary Electron Yield Data,” Surface and Interface Analysis, 2005, 37, p. 895-900. 2. D.C. Joy: “A Database on Electron-Solid Interactions,” Scanning, 1995, 17, p. 270-275. 3. J.T.L. Thong: Electron Beam Testing Technology, Plenum Press, New York, NY, 1993. 4. C. Shaw, C.C. Tsao, and T.R. Lundquist: “Measuring Backside Voltage of an Integrated Circuit,” U.S. Patent 6,872,581 B2, 2005. 5. R. Schlangen, et al.: “Functional IC Analysis Through Chip Backside with Nano Scale Resolution – E-beam Probing in FIB Trenches to STI Level,” Proc. Int. Symp. Test. Fail. Anal. (ISTFA), 2006, p. 376-381. 6. R.K. Jain, et al.: “Novel Flip-Chip Probing Methodology using Electron Beam Probing,” Proc. 14th IPFA, 2007, p. 39-43. 7. T. Tong, et al.: “Electron Beam Probing of Active Advanced FinFET Circuit with Fin Level Resolution,” Proc. Int. Symp. Test. Fail. Anal. (ISTFA), 2018, p. 345-348. 8. J. Vickers, et al.: “Failure Analysis of FinFET Circuitry at GHz Speeds using Voltage-contrast and Stroboscopic Techniques on a Scanning Electron Microscope,” Proc. Int. Symp. Test. Fail. Anal. (ISTFA), 2019, p. 197-203. 9. J. Huening, et al.: “High Spatial and Energy Resolution Fault Isolation by Electron Beam Probing for Advanced Technology Nodes,” Proc. Int. Symp. Test. Fail. Anal. (ISTFA), 2020, p. 100-102. 10. S.L. Ting, et al.: “Simple Circuit Edit Passive Voltage Contrast Technique to Identify Leakage Location,” Proc. Int. Symp. Test. Fail. Anal. (ISTFA), 2020, p. 70-74. Fig. 4 Frequency-map image of an IC showing active transistors switching at the DUT clock frequency. In most regions where no clock signal is present, only noise is seen in the image, but for transistors switching in phase with the clock signal, bright pixels are apparent, while transistors switching out of phase with the DUT clock appear as darker pixels. Such images require acquisition times on the order of a minute. ABOUT THE AUTHORS James Vickers received a B.S. in physics from Purdue University in 1986, and after three years working at AT&T Bell Laboratories went to the University of California at Berkeley to earn his Ph.D. in physics. He has been designing novel test equipment his entire professional life with products ranging from the EmiScope through today’s e-beam product line. Blake Freeman received a B.S. in physics and mathematics from the University of Washington in 2011. He earned his Ph.D. from UCLA in 2017, conducting research on quantum computing using semiconductor-based lateral quantum dots. After completing graduate school, he joined the electrical failure analysis group at Thermo Fisher Scientific, where he now serves as a staff systems design engineer. Neel Leslie graduated from San Jose State University with a B.S. in chemistry. He joined DCG Systems as a development engineer, and later moved to applications. He is currently the product marketing manager in charge of the e-beam probing systems at Thermo Fisher Scientific.
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