Piezoelectric ZnO films by r.f. sputtering

Jyrki Molarius, Jyrki Kaitila, Tuomas Pensala, Markku Ylilammi

Research output: Contribution to journalArticleScientificpeer-review

44 Citations (Scopus)

Abstract

Piezoelectric zinc oxide films are used in microelectromechanical systems (MEMS) applications, where they can be used in sensors to detect, e.g., pressure or acceleration. Beside sensors, ZnO films are applied in activation devices, where force is needed. Conductive-doped zinc oxide (most often with aluminum) is also used in optoelectronics. Piezoelectric films including AlN and ZnO are more difficult to produce than the corresponding conductive materials. In order to achieve good piezoelectricity in ZnO films, they have to possess high purity, a (0 0 1) orientation (ZnO has hexagonal crystal structure), high resistivity, and fine columnar microstructure perpendicular to the substrate. We have used r.f. magnetron (13.56 MHz) sputtering from a ZnO target in an oxygen atmosphere to achieve the piezoelectric ZnO. The aim of this work has been to develop an r.f. sputtering process for ZnO to achieve highly piezoelectric thin films. As a test vehicle to measure the piezoelectricity of the ZnO films we have fabricated resonators and passband filters in the 1–2 GHz range using standard microelectronics photolithography, deposition, and etching techniques on 100-mm diameter Corning glass or silicon wafers. The influence of the sputtering-process parameters on the film properties has been studied by X-ray diffraction, scanning electron microscopy, atomic force microscopy, and electrical measurements. In this study, the effects of the process parameters on the final material properties of the ZnO film are discussed in detail.
Original languageEnglish
Pages (from-to)431-435
Number of pages5
JournalJournal of Materials Science: Materials in Electronics
Volume14
Issue number5-7
DOIs
Publication statusPublished - 2003
MoE publication typeA1 Journal article-refereed

Fingerprint

Sputtering
sputtering
Zinc Oxide
piezoelectricity
Piezoelectricity
Zinc oxide
zinc oxides
test vehicles
Conductive materials
sensors
Sensors
Photolithography
photolithography
Aluminum
Silicon wafers
microelectronics
Microelectronics
Crystal orientation
Optoelectronic devices
electrical measurement

Cite this

Molarius, Jyrki ; Kaitila, Jyrki ; Pensala, Tuomas ; Ylilammi, Markku. / Piezoelectric ZnO films by r.f. sputtering. In: Journal of Materials Science: Materials in Electronics. 2003 ; Vol. 14, No. 5-7. pp. 431-435.
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abstract = "Piezoelectric zinc oxide films are used in microelectromechanical systems (MEMS) applications, where they can be used in sensors to detect, e.g., pressure or acceleration. Beside sensors, ZnO films are applied in activation devices, where force is needed. Conductive-doped zinc oxide (most often with aluminum) is also used in optoelectronics. Piezoelectric films including AlN and ZnO are more difficult to produce than the corresponding conductive materials. In order to achieve good piezoelectricity in ZnO films, they have to possess high purity, a (0 0 1) orientation (ZnO has hexagonal crystal structure), high resistivity, and fine columnar microstructure perpendicular to the substrate. We have used r.f. magnetron (13.56 MHz) sputtering from a ZnO target in an oxygen atmosphere to achieve the piezoelectric ZnO. The aim of this work has been to develop an r.f. sputtering process for ZnO to achieve highly piezoelectric thin films. As a test vehicle to measure the piezoelectricity of the ZnO films we have fabricated resonators and passband filters in the 1–2 GHz range using standard microelectronics photolithography, deposition, and etching techniques on 100-mm diameter Corning glass or silicon wafers. The influence of the sputtering-process parameters on the film properties has been studied by X-ray diffraction, scanning electron microscopy, atomic force microscopy, and electrical measurements. In this study, the effects of the process parameters on the final material properties of the ZnO film are discussed in detail.",
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Piezoelectric ZnO films by r.f. sputtering. / Molarius, Jyrki; Kaitila, Jyrki; Pensala, Tuomas; Ylilammi, Markku.

In: Journal of Materials Science: Materials in Electronics, Vol. 14, No. 5-7, 2003, p. 431-435.

Research output: Contribution to journalArticleScientificpeer-review

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AU - Pensala, Tuomas

AU - Ylilammi, Markku

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AB - Piezoelectric zinc oxide films are used in microelectromechanical systems (MEMS) applications, where they can be used in sensors to detect, e.g., pressure or acceleration. Beside sensors, ZnO films are applied in activation devices, where force is needed. Conductive-doped zinc oxide (most often with aluminum) is also used in optoelectronics. Piezoelectric films including AlN and ZnO are more difficult to produce than the corresponding conductive materials. In order to achieve good piezoelectricity in ZnO films, they have to possess high purity, a (0 0 1) orientation (ZnO has hexagonal crystal structure), high resistivity, and fine columnar microstructure perpendicular to the substrate. We have used r.f. magnetron (13.56 MHz) sputtering from a ZnO target in an oxygen atmosphere to achieve the piezoelectric ZnO. The aim of this work has been to develop an r.f. sputtering process for ZnO to achieve highly piezoelectric thin films. As a test vehicle to measure the piezoelectricity of the ZnO films we have fabricated resonators and passband filters in the 1–2 GHz range using standard microelectronics photolithography, deposition, and etching techniques on 100-mm diameter Corning glass or silicon wafers. The influence of the sputtering-process parameters on the film properties has been studied by X-ray diffraction, scanning electron microscopy, atomic force microscopy, and electrical measurements. In this study, the effects of the process parameters on the final material properties of the ZnO film are discussed in detail.

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