Performance of thin AlxOy, SixNy and AlN passivation layers for high temperature SAW device applications

Gillinger, M.; Knobloch, Theresia; Marković, A.; Pfusterschmied, Georg; Schneider, Michael; Schmid, U.

doi:10.1016/j.mssp.2018.02.028

Cited by 13 publications

(4 citation statements)

References 25 publications

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“…In Figure 2b,c, the corresponding (002) peaks are stable over the entire 24 h of temperature load. However, as shown in Figure 2d, at 900 °C, the crystallographic (002) phase in Y 0.15 Al 0.85 N starts to disappear after 1 h and is almost completely gone after about 2 h. For pure AlN, M. Gillinger et al, [ 31 ] observed a similar behavior at 1000 °C, where the (002) peak disappears after about 2 h. [ 31 ] For ScAlN, similar investigations were performed, [ 32,33 ] demonstrating its crystalline stability at high temperatures up to 1000 °C. [ 32 ] This research work demonstrates, for the first time, that although the oxidation resistance is reduced in Y 0.15 Al 0.85 N compared to pure AlN, it is still sufficiently high for most of the semiconductor device fabrication process steps as well as during device operation for a large range of application scenarios.…”

Section: Resultsmentioning

confidence: 99%

“…[ 30 ] Latest above 900 °C, the in‐diffusion of oxygen, most probably in parallel with the out‐diffusion of nitrogen, leads to an amorphizamorphization of the originally polycrystalline microstructure in combination with a strong change in the chemical layer composition. [ 31 ] As the sample did not show the (002) crystallographic phase above 900 °C, 24 h high‐temperature stability tests were conducted again in a pure oxygen atmosphere at 700, 800, and 900 °C to study the long‐term oxygen resistance under such harsh environmental conditions. The corresponding Bragg–Brentano scans for these temperatures are given in Figure 2b–d, respectively.…”

Section: Resultsmentioning

confidence: 99%

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Impact of AlN Seed Layer on Microstructure and Piezoelectric Properties of Y_xAl₁₋_xN (x = 15%) Thin Films

Pandit

Schneider

Berger

et al. 2022

Adv Elect Materials

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Alloying transition metals into aluminum nitride (AlN) has surged over the past decade to increase the piezoelectric performance of AlN for microelectromechanical systems (MEMS) applications. So far, the highest piezoelectric coefficients have been achieved by alloying scandium into AlN. But, most recently published studies have theoretically predicted by ab‐initio calculations that yttrium can also be a promising and less expensive alternative to scandium. This paper focuses on the impact of an AlN seed layer on the growth and piezoelectric properties of sputter‐deposited, polycrystalline Y0.15Al0.85N thin films on a silicon substrate. For the first time, the increase in piezoelectric performance of YxAl1−xN (x = 15%) thin films with a d33 of ≈7.85 pC N−1 due to this seed layer approach is presented, thus reaching in good agreement theoretical predictions. Furthermore, for the first time, the crystalline stability of Y0.15Al0.85N layers in a pure oxygen environment up to 1200 °C is reported, demonstrating a high oxygen resistance up to 800 °C even in this harsh environment. Detailed thin film analysis is done with various techniques such as X‐ray diffraction, atomic force microscopy, nano‐indentation, and high‐resolution transmission electron microscopy and correlated with piezoelectric coefficient measurements.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Impact of AlN Seed Layer on Microstructure and Piezoelectric Properties of Y_xAl₁₋_xN (x = 15%) Thin Films

Pandit

Schneider

Berger

et al. 2022

Adv Elect Materials

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“…Above 900 °C, increased oxygen diffusion into the film occurs, leading to an amorphization of the layer. Gillinger et al [ 31 ] observed similar behavior for pure AlN, where he showed the stability of AlN up to 1000 °C. Similar investigations were performed for ScAlN, [ 32 ] demonstrating its crystalline stability up to high temperatures of 1000 °C.…”

Section: Resultsmentioning

confidence: 72%

Enhancement of Piezoelectric Response in Yttrium Aluminum Nitride (Y_xAl_1‐xN) Thin Films

Pandit,

Schneider,

Schwarz

et al. 2023

Adv Eng Mater

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Alloying rare earth elements into aluminum nitride (AlN) thin films to increase the piezoelectric response has gained a lot of attention in the past few years. Many rare earth elements were investigated in which scandium alloying has resulted in the highest piezoelectric response for AlN. At the same time, researchers have also theoretically explored yttrium alloying as a feasible and economical alternative to scandium. In this paper, we demonstrate for the first time experimentally the increase of the piezoelectric response of sputter‐deposited YxAl1–xN thin films as a function of increasing yttrium concentration as predicted by density functional theory calculations. By using differently manufactured targets, YxAl1–xN thin films with four different yttrium alloying concentrations (9, 12, 15 and 20 at%.) are synthesized. Detailed thin film analysis is carried out and the highest value of d 33 measured is 12 pC/N for Y0.2Al0.8N, which is a 250 % increase compared to pure AlN. Even more, the Young’s modulus decreases with increasing yttrium concentration in excellent agreement with theoretical predictions. Finally, Y0.15Al0.85N and Y0.2Al0.8N layers show high crystalline stability in pure oxygen environment up to 800˚C, demonstrating high oxidation resistance even under harsh environmental conditions.This article is protected by copyright. All rights reserved.

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“…Great efforts have been made to develop high-temperature surface-acoustic-wave (SAW) devices for many promising applications [1][2][3][4][5][6][7]. The propagation of acoustic waves is realized by the vibration of a piezoelectric substrate; thus, the performance of SAW devices is determined to a great extent by the mass loading effect of interdigital transducer electrodes (ITDs)-that is, too thick an electrode will decay the propagation of SAW and influence the performance of the device [8,9].…”

Section: Introductionmentioning

confidence: 99%

High‐Temperature Conductive Stability of ITO/Pt Bilayer‐Film Electrode for Applications in High‐Temperature SAW Devices

Mou

Peng

et al. 2022

Journal of Nanomaterials

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Surface-acoustic-wave (SAW) devices have been widely investigated over many years as demand has grown for information sensing above 1000°C. At such high temperatures, metal electrode creep occurs, thereby causing the transformation of an electrode from a continuous uniform film to a discontinuous film with hollows or isolated grains. In this study, 100 nm thick ITO conductive oxide film is deposited on 100 nm thick Pt film to form an ITO/Pt bilayer-film composite electrode for high-temperature SAW devices. According to this way, the conductive stability of the Pt film electrode at high temperature can be greatly improved. Compared with the initial value, the electrical conductivity of single-layer 100 nm thick Pt film decreases to 65.4% with the area fraction of Pt at 64.1%. Meanwhile, the electrical conductivity of ITO/Pt bilayer-film decreases to only 95% with the area fraction of Pt at 63.1%. Then, the enhancement of high-temperature conductive stability can be attributed to the added ITO conduction channels. These findings demonstrate a potential route to design multilayer electrodes that can operate above 1000°C with promising applications in SAW devices needing to operate at high temperatures.

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Performance of thin AlxOy, SixNy and AlN passivation layers for high temperature SAW device applications

Cited by 13 publications

References 25 publications

Impact of AlN Seed Layer on Microstructure and Piezoelectric Properties of Y_xAl₁₋_xN (x = 15%) Thin Films

Impact of AlN Seed Layer on Microstructure and Piezoelectric Properties of Y_xAl₁₋_xN (x = 15%) Thin Films

Enhancement of Piezoelectric Response in Yttrium Aluminum Nitride (Y_xAl_1‐xN) Thin Films

High‐Temperature Conductive Stability of ITO/Pt Bilayer‐Film Electrode for Applications in High‐Temperature SAW Devices

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Performance of thin AlxOy, SixNy and AlN passivation layers for high temperature SAW device applications

Cited by 13 publications

References 25 publications

Impact of AlN Seed Layer on Microstructure and Piezoelectric Properties of YxAl1−xN (x = 15%) Thin Films

Impact of AlN Seed Layer on Microstructure and Piezoelectric Properties of YxAl1−xN (x = 15%) Thin Films

Enhancement of Piezoelectric Response in Yttrium Aluminum Nitride (YxAl1‐xN) Thin Films

High‐Temperature Conductive Stability of ITO/Pt Bilayer‐Film Electrode for Applications in High‐Temperature SAW Devices

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Product

Resources

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Impact of AlN Seed Layer on Microstructure and Piezoelectric Properties of Y_xAl₁₋_xN (x = 15%) Thin Films

Impact of AlN Seed Layer on Microstructure and Piezoelectric Properties of Y_xAl₁₋_xN (x = 15%) Thin Films

Enhancement of Piezoelectric Response in Yttrium Aluminum Nitride (Y_xAl_1‐xN) Thin Films