Growth and Characterization of Al (111) Thin Film on Piezoelectric Wafers for SAW Device Fabrication for Space Applications

Authors

  • Manish Kumar Sahu Microelectronics Group, Space Applications Centre, ISRO, Ahmedabad, India https://orcid.org/0000-0001-6951-9060
  • Ajaya Kumar PS Microelectronics Group, Space Applications Centre, ISRO, Ahmedabad, India
  • Chiranjit Karmakar Microelectronics Group, Space Applications Centre, ISRO, Ahmedabad, India https://orcid.org/0000-0003-0622-7487
  • Gunjan Rastogi Thermal Systems Group, UR Rao Satellite Centre, ISRO, Bengaluru, India
  • R. K. Kaneriya Microelectronics Group, Space Applications Centre, ISRO, Ahmedabad, India https://orcid.org/0000-0002-1809-3976
  • R. B. Upadhyay Microelectronics Group, Space Applications Centre, ISRO, Ahmedabad, India

DOI:

https://doi.org/10.37256/nat.4120231624

Keywords:

SAW filters, electron beam evaporation, metallic thin films, X-ray diffraction, space applications

Abstract

Surface Acoustic Wave (SAW) filters provide precise frequency filtering in RF and IF range with a tiny footprint. Metallic thin films are the essence of such modern SAW filter technology. However, SAW filters realized using NiCr/Al thin films are limited to power levels of ~5 dBm at RF frequencies. This limitation on power level is due to the acousto-migration phenomenon in thin films at higher power levels. In order to enhance the power durability of SAW filters, the preferred oriented growth of Al along (111) crystallographic direction is one of the methods to reduce acousto-migration. This paper explores the growth and characterization of different metallization schemes (NiCr/Al & Ti/Al) on different piezoelectric wafers to achieve oriented Al (111) film growth. Metallic thin films were deposited using electron beam evaporation technique. High Resolution X-Ray Diffraction (HR-XRD) and Four Point Probe Method were used for crystallographic characterization and Sheet Resistance (SR) measurement, respectively. Atomic Force Microscopy (AFM) and surface profiler were used to characterize the surface morphology of the deposited films. FWHM of 4.12 degree of rocking curve on Al (111) peak has been achieved for Ti/Al metal film deposited on ST-X Quartz piezoelectric wafer along with low sheet resistance of 124 mΩ/sq. A deposition rate of 1 Å/s for Ti and 7 Å/s for Al at a deposition temperature of 100 °C gave the best FWHM value for Al (111) orientation on ST-X Quartz wafer. Space qualification tests were also successfully performed on Ti/Al metalized wafers under extreme environmental conditions. The results obtained in this work demonstrate the suitability of Ti as an under layer to grow preferred oriented Al film along (111) orientation and thus to be used in the fabrication of high-power SAW devices for space applications.

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Published

2022-08-18

How to Cite

1.
Manish Kumar Sahu, Ajaya Kumar PS, Chiranjit Karmakar, Gunjan Rastogi, R. K. Kaneriya, R. B. Upadhyay. Growth and Characterization of Al (111) Thin Film on Piezoelectric Wafers for SAW Device Fabrication for Space Applications . Nanoarchitectonics [Internet]. 2022 Aug. 18 [cited 2022 Dec. 1];4(1):16-25. Available from: https://ojs.wiserpub.com/index.php/NAT/article/view/1624

Issue

Section

Research article