材料科学
原子层沉积
微电子机械系统
退火(玻璃)
压电
氮化物
光电子学
Crystal(编程语言)
薄膜
图层(电子)
纳米技术
复合材料
计算机科学
程序设计语言
作者
Elmeri Österlund,Heli Seppänen,Kristina Bespalova,Ville Miikkulainen,Mervi Paulasto‐Kröckel
出处
期刊:Journal of vacuum science & technology
[American Institute of Physics]
日期:2021-03-08
卷期号:39 (3)
被引量:22
摘要
Atomic layer deposition (ALD) of aluminum nitride (AlN) using in situ atomic layer annealing (ALA) is studied for microelectromechanical systems (MEMS). Effective piezoelectric in-plane actuation and sensing requires deposition of high crystal quality and (0002) oriented AlN on vertical sidewalls of MEMS structures. Previous studies have shown that the crystal quality of ALD AlN can be significantly improved using ALA but have not studied the conformal coverage or crystal quality on metal electrodes, which are required for piezoelectric MEMS devices. In this study, AlN thin films are deposited on Si, Al, Pt, and on vertical sidewalls etched into Si. The AlN microstructure and properties are studied using x-ray diffraction methods, transmission electron microscopy, and Fourier transform infrared spectroscopy. The conformal coverage is evaluated by measuring the film thickness on the vertical sidewalls. The effects of postdeposition annealing are studied as well. This study aims to enable effective piezoelectric actuation and sensing for MEMS sensors. The conformal coverage of the ALA ALD process is excellent and AlN has the best crystal quality and degree of orientation when deposited on Al. The as-deposited films contain oxygen impurities, which might be detrimental to the piezoelectric properties of AlN. Annealing at high temperatures reduced the number of impurities but did not improve the crystal quality.
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