SiO_2薄膜的微观结构与驻极体特性的相关性研究

Study on relations between microstructures and electret properties of SiO_2 film

SiO2驻极体具有优异的电荷储存能力,其具有器件制作工艺可与微机械加工技术兼容、适合集成化生产等优点,一直是微器件和传感器领域研究的热点。采用电晕充电和表面电位测试等技术研究了等离子增强化学气相沉积(PECVD)和电子束蒸发两种方法制备的SiO2薄膜的驻极体特性,发现PECVD方法制备的SiO2薄膜的驻极体性能明显优于电子束蒸发制备的SiO2薄膜。结合扫描探针显微镜、X射线衍射及激光拉曼光谱等技术对两种薄膜的结构分析表明,其性能差异与薄膜形貌和微观结构密切相关。PECVD方法制备的非晶SiO2薄膜由纳米级非晶颗粒组成,颗粒间存在大量无序度较高的界面,由此产生的"界面陷阱"是导致PECVD制备的SiO2薄膜具有更佳电荷存储稳定性的根本原因。

Since it possesses excellent advantages such as the outstanding ability of charge storage,the compati-bility of device-making with the standard lithography in micro-electron-mechanical process,and the suitability for the integration manufacture,the SiO2 film electret was the hot research point in the micro-device and sensor fields.In this paper,the electret properties of the SiO2 films,prepared by electron evaporation and PECVD methods,were studied by using the corona charging and surface potential testing technologies.It was found that the electret property of the sample prepared by PECVD method was distinctively better than that of the sample prepared by electron evaporation method.The micro-structures of the SiO2 thin films were analyzed by scanning probe microscope,X-ray diffraction and Raman analysis equipments,it was found that the electret property was tightly correlated to the micro-structure of SiO2 thin film.The SiO2 film prepared by PECVD method was composed of nanoscale amorphous particles and possesses a great deal of particle interfaces,these interfaces serve as charge traps and the existence of these interface traps was the fundamental reason for the e-ven better charge store stability of the film.