TY - JOUR
T1 - Stability and residual stresses of sputtered wurtzite AlScN thin films
AU - Österlund, Elmeri
AU - Ross, Glenn
AU - Caro, Miguel A.
AU - Paulasto-Kröckel, Mervi
AU - Hollmann, Andreas
AU - Klaus, Manuela
AU - Meixner, Matthias
AU - Genzel, Christoph
AU - Koppinen, Panu
AU - Pensala, Tuomas
AU - Žukauskaitė, Agnė
AU - Trebala, Michal
N1 - Funding Information:
E. Österlund appreciates the funding from the European Space Agency (NPI Grant No. 4000116390) and Aalto ELEC Doctoral School. Dr. Žukauskaitė appreciates the funding from FhG Internal Programs under Grant No. Attract 005-600636. Dr. Vesa Vuorinen and Dr. Hongqun Dong are acknowledged for useful discussions. This research was conducted as a part of the EU project POSITION II (Ecsel-783132-Position-II-2017-IA) and performed partly at the Aalto University OtaNano–Micronova Nanofabrication Centre and Nanomicroscopy Center.
Publisher Copyright:
© 2021 authors. Published by the American Physical Society.
PY - 2021/3
Y1 - 2021/3
N2 - Scandium-alloying of aluminum nitride (AlScN) enhances the piezoelectric properties of the material and increases the performance of piezoelectric microelectromechanical systems (MEMS). However, this enhancement is caused by the destabilization of the wurtzite phase and so far the stability of AlScN thin films has not been sufficiently studied. Stability is especially important for piezoelectric devices because changes to the film microstructure or residual stress can lead to drastic changes in the device behavior. The stability of AlScN is investigated by annealing sputtered films and characterizing the resulting changes. It is found that the wurtzite phase of Al0.7Sc0.3N is stable at least up to 1000°C and annealing increases the crystal quality, reaching a maximum at 800°C. When annealed for more than 100 h at 1000°C, argon used in sputtering segregates into the grain boundaries and causes compressive strains and formation of rock-salt phase. Additionally, annealing at 1000∘C for 5 h reduces the average tensile stress by approximately 1 GPa.
AB - Scandium-alloying of aluminum nitride (AlScN) enhances the piezoelectric properties of the material and increases the performance of piezoelectric microelectromechanical systems (MEMS). However, this enhancement is caused by the destabilization of the wurtzite phase and so far the stability of AlScN thin films has not been sufficiently studied. Stability is especially important for piezoelectric devices because changes to the film microstructure or residual stress can lead to drastic changes in the device behavior. The stability of AlScN is investigated by annealing sputtered films and characterizing the resulting changes. It is found that the wurtzite phase of Al0.7Sc0.3N is stable at least up to 1000°C and annealing increases the crystal quality, reaching a maximum at 800°C. When annealed for more than 100 h at 1000°C, argon used in sputtering segregates into the grain boundaries and causes compressive strains and formation of rock-salt phase. Additionally, annealing at 1000∘C for 5 h reduces the average tensile stress by approximately 1 GPa.
UR - http://www.scopus.com/inward/record.url?scp=85104267135&partnerID=8YFLogxK
U2 - 10.1103/PhysRevMaterials.5.035001
DO - 10.1103/PhysRevMaterials.5.035001
M3 - Article
AN - SCOPUS:85104267135
VL - 5
JO - Physical Review Materials
JF - Physical Review Materials
SN - 2475-9953
IS - 3
M1 - 035001
ER -