Abstract
Partial substitution of aluminium by scandium in the wurtzite structure of aluminium nitride (AlN) leads to a large increase of the piezoelectric response by more than a factor of 2. Therefore, aluminium scandium nitride (ASN) thin films attracted much attention to improve piezoelectric MEMS devices such as RF filters, sensors, micro actuators and energy harvesting devices. In this work, process-microstructure-property relationships of ASN thin films containing up to 42% Sc were investigated. Like AlN thin films, ASN films are sputter deposited at 300–350°C with pulsed DC powered magnetrons. The influence of the process parameters on the film structure, the intrinsic stress and the piezoelectric response was investigated in order to achieve optimal piezoelectric coefficients up to high Sc concentrations. X-Ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyse the quality of c-axis texture. The films showed exclusively (002) texture with rocking-curve widths in the range of 1.3–2° (FHWM). The films were further analysed by scanning electron microscopy (SEM). The Sc content was determined by energy-dispersive X-ray spectroscopy (EDX). A good compositional homogeneity in the range of 0.5–1 at.% was achieved between border and centre of 200-mm wafers. So far, we obtained ASN films with transversal piezoelectric coefficients of up to e31,f = −2.77 C/m2, which is a factor 2.6 higher than in pure AlN thin films.
| Original language | English |
|---|---|
| Pages (from-to) | 2-6 |
| Number of pages | 5 |
| Journal | Surface and Coatings Technology |
| Volume | 343 |
| DOIs | |
| Publication status | Published - 15 Jun 2018 |
| MoE publication type | A1 Journal article-refereed |
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Keywords
- Aluminium scandium nitride
- C-axis texture
- Electron microscopy
- Piezoelectric thin films
- Reactive magnetron sputtering
- X-ray diffraction
Cite this
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Piezoelectric and structural properties of c-axis textured aluminium scandium nitride thin films up to high scandium content. / Mertin, Stefan; Heinz, Bernd; Rattunde, Oliver; Christmann, Gabriel; Dubois, Marc Alexandre; Nicolay, Sylvain; Muralt, Paul.
In: Surface and Coatings Technology, Vol. 343, 15.06.2018, p. 2-6.Research output: Contribution to journal › Article › Scientific › peer-review
TY - JOUR
T1 - Piezoelectric and structural properties of c-axis textured aluminium scandium nitride thin films up to high scandium content
AU - Mertin, Stefan
AU - Heinz, Bernd
AU - Rattunde, Oliver
AU - Christmann, Gabriel
AU - Dubois, Marc Alexandre
AU - Nicolay, Sylvain
AU - Muralt, Paul
PY - 2018/6/15
Y1 - 2018/6/15
N2 - Partial substitution of aluminium by scandium in the wurtzite structure of aluminium nitride (AlN) leads to a large increase of the piezoelectric response by more than a factor of 2. Therefore, aluminium scandium nitride (ASN) thin films attracted much attention to improve piezoelectric MEMS devices such as RF filters, sensors, micro actuators and energy harvesting devices. In this work, process-microstructure-property relationships of ASN thin films containing up to 42% Sc were investigated. Like AlN thin films, ASN films are sputter deposited at 300–350°C with pulsed DC powered magnetrons. The influence of the process parameters on the film structure, the intrinsic stress and the piezoelectric response was investigated in order to achieve optimal piezoelectric coefficients up to high Sc concentrations. X-Ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyse the quality of c-axis texture. The films showed exclusively (002) texture with rocking-curve widths in the range of 1.3–2° (FHWM). The films were further analysed by scanning electron microscopy (SEM). The Sc content was determined by energy-dispersive X-ray spectroscopy (EDX). A good compositional homogeneity in the range of 0.5–1 at.% was achieved between border and centre of 200-mm wafers. So far, we obtained ASN films with transversal piezoelectric coefficients of up to e31,f = −2.77 C/m2, which is a factor 2.6 higher than in pure AlN thin films.
AB - Partial substitution of aluminium by scandium in the wurtzite structure of aluminium nitride (AlN) leads to a large increase of the piezoelectric response by more than a factor of 2. Therefore, aluminium scandium nitride (ASN) thin films attracted much attention to improve piezoelectric MEMS devices such as RF filters, sensors, micro actuators and energy harvesting devices. In this work, process-microstructure-property relationships of ASN thin films containing up to 42% Sc were investigated. Like AlN thin films, ASN films are sputter deposited at 300–350°C with pulsed DC powered magnetrons. The influence of the process parameters on the film structure, the intrinsic stress and the piezoelectric response was investigated in order to achieve optimal piezoelectric coefficients up to high Sc concentrations. X-Ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyse the quality of c-axis texture. The films showed exclusively (002) texture with rocking-curve widths in the range of 1.3–2° (FHWM). The films were further analysed by scanning electron microscopy (SEM). The Sc content was determined by energy-dispersive X-ray spectroscopy (EDX). A good compositional homogeneity in the range of 0.5–1 at.% was achieved between border and centre of 200-mm wafers. So far, we obtained ASN films with transversal piezoelectric coefficients of up to e31,f = −2.77 C/m2, which is a factor 2.6 higher than in pure AlN thin films.
KW - Aluminium scandium nitride
KW - C-axis texture
KW - Electron microscopy
KW - Piezoelectric thin films
KW - Reactive magnetron sputtering
KW - X-ray diffraction
UR - http://www.scopus.com/inward/record.url?scp=85042142769&partnerID=8YFLogxK
U2 - 10.1016/j.surfcoat.2018.01.046
DO - 10.1016/j.surfcoat.2018.01.046
M3 - Article
AN - SCOPUS:85042142769
VL - 343
SP - 2
EP - 6
JO - Surface and Coatings Technology
JF - Surface and Coatings Technology
SN - 0257-8972
ER -