Journal of the Korean Society for Nondestructive Testing (비파괴검사학회지)

The Korean Society for Nondestructive Testing (한국비파괴검사학회)
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Propagation of Bulk Longitudinal Waves in Thin Films Using Laser Ultrasonics

레이저 초음파를 이용한 체적종파의 박막 내 전파특성 연구

  • Kim, Yun Young (Department of Mechanical Engineering, Dong-eui University)
  • 김윤영 (동의대학교 기계공학과)
  • Received : 2016.06.01
  • Accepted : 2016.07.03
  • Published : 2016.08.30
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Abstract

This paper presents the investigation of the propagation behavior of bulk longitudinal waves generated by an ultrafast laser system in thin films. A train of femtosecond laser pulses was focused onto the surface of a 150-nm thick metallic (chromium or aluminum) film on a silicon substrate to excite elastic waves, and the change in thermoreflectance at the spot was monitored to detect the arrival of echoes from the film/substrate interface. The experimental results show that the film material characteristics such as the wave velocity and Young's modulus can be evaluated through curve-fitting in numerical solutions. The material properties of nanoscale thin films are difficult to measure using conventional techniques. Therefore, this research provides an effective method for the nondestructive characterization of nanomaterials.

본 논문에서는 나노스케일 금속박막 내에서 체적종파가 전파하는 특성을 연구하였다. 실리콘(100) 기판 위에 150 nm 두께의 크로뮴 혹은 알루미늄 박막을 적층하여 시편을 제작하였으며, 펨토초 레이저 시스템으로 구성된 시간영역 열반사율 기법(time-domain theromoreflectance technique)을 이용하여 박막 표면으로부터 여기된 탄성파가 박막과 기판의 계면에서 반향될 때 발생하는 신호를 검출하였다. 체적종파의 거동을 모사하는 열탄성 방정식을 수치해석적으로 풀어 측정값과 곡선맞춤함으로써 박막의 체적종파 속도와 탄성계수를 평가할 수 있었으며, 결과를 문헌값과 비교하여 그 타당성을 검증하였다. 본 연구로부터 확립된 레이저 계측법은 나노재료의 특성평가에 적합함을 보여주며, 이는 기존의 접촉식 파괴식 검사법의 한계를 뛰어넘을 대안을 제시한다.

Keywords

References

  1. K. Chang, Y. Y. Kim, J. Sue, H. Lee, W. Chung, K. Lee, Y. Park, E. Jung and I. Chung, "The novel stress simulation method for contemporary DRAM capacitor arrays," 2013 International Conference on Simulation of Semiconductor Processes and Devices, Glasgow, UK, pp. 424-427 (2013)
  2. Y. Y. Kim, H. A. Alwi, R. Awang and S. Krishnaswamy, "Effects of deposition time duration on thermal diffusivity of hydrogenated amorphous carbon films," Japanese Journal of Applied Physics, Vol. 50, No. 12R, 125602 (2011) https://doi.org/10.7567/JJAP.50.125602
  3. Y. Y. Kim, H. A. Alwi, R. Awang and S. Krishnaswamy, "Influence of radio frequency power on thermal diffusivity of plasma enhanced chemical vapor deposition-grown hydrogenated amorphous carbon thin-films," Journal of Applied Physics, Vol. 109, No. 11, 113503 (2011) https://doi.org/10.1063/1.3592291
  4. H. Lee and J. H. Lee, "Evaluation of material characteristics by micro/nano indentation tests," Transactions of the Korean Society of Mechanical Engineers A, Vol. 32, No. 32, pp. 805-816 (2008) https://doi.org/10.3795/KSME-A.2008.32.10.805
  5. D. J. Lee, Y. Cho, K. W. Jang, S. H. Cho and B. Y. Ahn, "Measurement of elastic constants of thin metallic foil by guided wave dispersion characteristics," Journal of the Korean Society for Nondestructive Testing, Vol. 32, No. 1, pp. 1-46 (2012) https://doi.org/10.7779/JKSNT.2012.32.1.001
  6. C. A. Paddock and G. L. Eesley, "Transient thermoreflectance from thin metal films," Journal of Applied Physics, Vol. 60, No. 1, pp. 285-290 (1986) https://doi.org/10.1063/1.337642
  7. D. G. Cahill, W. K. Ford, K. E. Goodson, G. D. Mahan, A. Majumdar, H. J. Maris, R. Merlin and S. R. Phillpot, "Nanoscale thermal transport," Applied Physics Reviews, Vol. 93, No. 2, pp. 793-818 (2003) https://doi.org/10.1063/1.1524305
  8. G. A. Antonelli, B. Perrin, B. C. Daly and D. G. Cahill, "Characterization of mechanical and thermal properties using ultrafast optical metrology," MRS Bulletin, Vol. 31, No. 8, pp. 607-613 (2016)
  9. Y. Y. Kim and S. Krishnaswamy, "Nondestructive evaluation of material properties of nanoscale thin-films using ultrafast optical pump-probe methods," Journal of the Korean Society for Nondestructive Testing, Vol. 32, No. 2, pp. 115-121 (2012) https://doi.org/10.7779/JKSNT.2012.32.2.115
  10. J. D. Anderson, "Computational Fluid Dynamics," McGraw-Hill, Singapore (1995)
  11. D. E. Gray, "American Institute of Physics Handbook," McGraw-Hill, New York (1982)
  12. G. Simmons and H. Wang, "Single Crystal Elastic Constants and Calculated Aggregate Properties: A Handbook," MIT Press, Cambridge (1971)
  13. B. Knight, J. Braunstein, J. F. Cox and J. Frankel, "Laser-ultrasonic characterization of electrodeposited chromium coatings," Review of Progress in Quantitative Nondestructive Evaluation, Vol. 18, pp. 365-372 (1999)
  14. D. Schneider and M. D. Tucker, "Nondestructive characterization and evaluation of thin films by laser-induced ultrasonic surface waves," Thin Solid Films, Vol. 290-291, pp. 305-311 (1996) https://doi.org/10.1016/S0040-6090(96)09029-3
  15. S. G. Nilsson, X. Borrise and L. Montelius, "Size effect on Young's modulus of thin chromium cantilevers," Applied Physics Letters, Vol. 85, No. 16, 3555 (2004) https://doi.org/10.1063/1.1807945
  16. M. Chinmulgund, R. B. Inturi and J. A. Barnard, "Effect of Ar gas pressure on growth, structure, and mechanical properties of sputtered Ti, Al, TiAl, and $Ti_3Al$ films," Thin Solid Films, Vol. 270, No. 1-2, pp. 260-263 (1995) https://doi.org/10.1016/0040-6090(95)06990-9
  17. B. Rashidian and M. G. Allen, "Electrothermal microactuators based on dielectric loss heating," IEEE Proceedings of Micro Electro Mechanical Systems, Fort Lauderdale, Florida, USA, pp. 24-29 (1993)
  18. A. Reddy, H. Kahn and A. H. Heuer, "A MEMS-based evaluation of the mechanical properties of metallic thin films," Journal of Microelectromechanical Systems, Vol. 16, No. 3, pp. 650-658 (2007) https://doi.org/10.1109/JMEMS.2007.892912
  19. Y. H. Kim, J. K. Lee, and H. C. Kim, "Observation of shear wave modes in the echoes of the longitudinal wave transducer," Review of Progress in Quantitative Nondestructive Evaluation, Vol. 15, pp. 987-994 (1996)

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