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.

中文翻译：

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使用原子层退火的AlN原子层沉积-在垂直侧壁上获得高质量的AlN

研究了用于微机电系统（MEMS）的使用原位原子层退火（ALA）的氮化铝（AlN）的原子层沉积（ALD）。有效的压电面内激励和感测要求在MEMS结构的垂直侧壁上沉积高质量的晶体和（0002）取向的AlN。先前的研究表明，使用ALA可以显着改善ALD AlN的晶体质量，但尚未研究压电MEMS器件所需的金属电极上的保形覆盖率或晶体质量。在这项研究中，AlN薄膜沉积在Si，Al，Pt以及蚀刻到Si的垂直侧壁上。使用X射线衍射方法，透射电子显微镜和傅里叶变换红外光谱研究了AlN的微观结构和性能。通过测量垂直侧壁上的膜厚来评估保形覆盖率。还研究了沉积后退火的影响。这项研究旨在为MEMS传感器实现有效的压电驱动和感测。ALA ALD工艺的保形覆盖范围极佳，当沉积在Al上时，AlN具有最佳的晶体质量和取向度。所沉积的膜包含氧杂质，这可能对AlN的压电性能有害。高温退火减少了杂质的数量，但并未改善晶体质量。ALA ALD工艺的保形覆盖范围极佳，当沉积在Al上时，AlN具有最佳的晶体质量和取向度。所沉积的膜包含氧杂质，这可能对AlN的压电性能有害。高温退火减少了杂质的数量，但并未改善晶体质量。ALA ALD工艺的保形覆盖范围极佳，当沉积在Al上时，AlN具有最佳的晶体质量和取向度。所沉积的膜包含氧杂质，这可能对AlN的压电性能有害。高温退火减少了杂质的数量，但并未改善晶体质量。