Structural Analysis of Sputtered Sc(x)Al(1-x)N Layers for Sensor Applications

Abstract:

Scandium aluminum nitride (ScxAl1-xN) is a promising material for sensor applications as it exhibits enhanced piezoelectric properties compared to pristine AlN while maintaining other advantageous properties like high thermal stability. Magnetoelectric sensors in particular are used to detect magnetic fields which leads to special requirements regarding the investigated ScAlN in order to achieve high sensor sensitivities. Co-sputtered ScAlN layers are investigated in this work using XRD, XPS, FTIR and Raman spectroscopy for scandium concentrations from 0 to 34 %. The impact of Sc incorporation regarding residual biaxial strain and bond softening is discussed on basis of the experimental results. The activity of the B1 and E2 modes found in the FTIR measurements is of special interest as the presumably oxygen related excitation is expected to influence the piezoelectric properties.

• Periodical: Key Engineering Materials (Volume 865)
• Pages: 13-18
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.865.13
• Online since: September 2020
• Authors: Bernd Hähnlein*, Tim Hofmann, Katja Tonisch, Joerg Pezoldt, Jaroslav Kovac, Stefan Krischok
• Keywords: FTIR, Magnetoelectric Sensor, Raman, Scandium Aluminum Nitride, XPS, X-Ray Diffraction

References

[1] A. Kulkarni, K. Meurisch, I. Teliban, R. Jahns, T. Strunskus, A. Piorra, R. Knöchel, F. Faupel, Giant magnetoelectric effect at low frequencies in polymer-based thin film composites, Appl. Phys. Lett. 104, (2014) 022904.

DOI: 10.1063/1.4860664

[2] H. Qu, CMOS MEMS Fabrication Technologies and Devices, Micromachines 7 (2016) 14.

[3] M. Akiyama, T. Komohara, K. Kano, A. Teshigahara, Y. Takeuchi, N. Kawahara, Enhancement of Piezoelectric Response in Scandium Aluminum Nitride Alloy Thin Films Prepared by Dual Reactive Cosputtering, Adv. Mater. 21 (2009) 593-596.

DOI: 10.1002/adma.200802611

[4] M. Moreira, J. Bjuström, I. Katardjev, V. Yantchev, Aluminum scandium nitride thin-film bulk acoustic resonators for wide band applications, Vacuum (2011) 23-26.

DOI: 10.1016/j.vacuum.2011.03.026

[5] M. Schneider, A. Bittner, U. Schmid, Thickness dependence of Young's modulus and residual stress of sputtered aluminum nitride thin films, Appl. Phys. Lett. 105 (2014) 201912. DOI: doi.org/10.1063/1.4902448.

DOI: 10.1063/1.4902448

[6] A. Teshigahara, K. Hashimoto, M. Akiyama, Scandium aluminum nitride: Highly piezoelectric thin film for RF SAW devices in multi GHz range, 2012 IEEE International Ultrasonics Symposium, Dresden (2012) 1-5.

DOI: 10.1109/ultsym.2012.0481

[7] B. Hähnlein, P. Schaaf, J. Pezoldt, Size effect of Young's modulus in AlN thin layers, J. Appl. Phys. 116 (2014) 124306.

DOI: 10.1063/1.4896496

[8] R. Melik, E. Unal, N.K. Perkgoz, C. Puttlitz, H.V. Demir, RF-MEMS Load Sensors with Enhanced Q-factor and Sensitivity in a Suspended Architecture, Microelectron. Eng. 88 (2011) 247-253.

DOI: 10.1016/j.mee.2010.10.041

[9] K. Tonisch, V. Cimalla, C. Foerster, H. Romanus, O. Ambacher, D. Dontsov, Piezoelectric properties of polycrystalline AlN thin films for MEMS application, Sensor Actuat. A 132 (2006) 658-663.

DOI: 10.1016/j.sna.2006.03.001

[10] S. Zhang, D. Hole, W.Y. Fu, C.J. Humphreys, M.A. Moram, Tunable optoelectronic and ferroelectric properties in Sc-based III-nitrides, J. Appl. Phys. 114 (2013) 133510.

DOI: 10.1063/1.4824179

[11] R. Deng, K. Jiang, D. Gall, Optical phonon modes in Al1−xScxN, J. Appl. Phys. 115 (2014) 013506.

[12] W.B. Wang, Y.Q. Fu, J.J. Chen, W.P. Xuan, J.K. Chen, X.Z. Wang, P. Mayrhofer, P.F. Duan, A. Bittner, U. Schmid, J.K. Luo, AlScN thin film based surface acoustic wavedevices with enhanced microfluidic performance, J. Micromech. Microeng. 26 (2016) 075006.

DOI: 10.1088/0960-1317/26/7/075006

[13] F.J. Manjón, D. Errandonea, A.H. Romero, N. Garro, J. Serrano, M. Kuball, Lattice dynamics of wurtzite and rocksalt AlN under high pressure: Effect of compression on the crystal anisotropy of wurtzite-type semiconductors, Phys. Rev. B 77 (2008) 205204.

DOI: 10.1103/physrevb.77.205204

[14] J. M. Wagner, F. Bechstedt, Properties of strained wurtzite GaN and AlN: Ab initio studies, Phys. Rev. B 66 (2002) 115202.

DOI: 10.1103/physrevb.66.115202

[15] U. Haboeck, H. Siegle, A. Hoffmann, C. Thomsen, Lattice dynamics in GaN and AlN probed with first- and second-order Raman spectroscopy, Phys. Status solidi C 0 (2003) 1710–1731.

DOI: 10.1002/pssc.200303130