Al_(2)O_(3)/HfO_(2)复合薄膜的介电性能研究  

Dielectric properties of Al_(2)O_(3)/HfO_(2) composite films

作　　者：牟舜禹 李瑞江 李少奎 熊文 林广 MU Shunyu;LI Ruijiang;LI Shaokui;XIONG Wen;LIN Guang(Chengdu Hongke Electronic Technology Co.,Ltd.,Chengdu 610100,China)

机构地区：[1]成都宏科电子科技有限公司,四川成都610100

出　　处：《电子元件与材料》2022年第11期1251-1257,共7页Electronic Components And Materials

摘　　要：采用ALD技术生长了超晶格结构Al_(2)O_(3)/HfO_(2)纳米叠层复合薄膜,并研究了复合薄膜的单层厚度、层厚比对其综合介电性能的影响规律。结果表明,降低复合薄膜的单层厚度可以有效提高综合介电性能,原因是降低单层厚度可有效增强界面极化效应,提高介电常数;而降低复合薄膜的单层厚度可以降低其结晶度,从而有效提高击穿场强和降低漏电流密度;复合薄膜的介电常数随着Al_(2)O_(3)∶HfO_(2)层厚比的降低而提高,这主要是因为HfO_(2)介电常数较高;但漏电流密度增大和击穿场强降低,这主要因为HfO_(2)结晶度较高造成的。进一步采用有限元模型模拟计算了复合薄膜的单层厚度、组分比例与介电常数的变化关系,其计算结果与实验结果基本一致;并采用第一性原理计算,证明了Al_(2)O_(3)/HfO_(2)界面存在内建电场,增强了介质材料在电场作用下的极化效应,界面极化是提高复合薄膜介电常数的主要原因。The superlattice Al_(2)O_(3)/HfO_(2) nano-stacked composite films were grown by ALD technology.The relationship between single layer thickness,layer thickness ratio and comprehensive dielectric properties of the composite films was also studied.The results show that reducing the single layer thickness of the composite films can effectively improve the dielectric properties.The reason is that reducing the single layer thickness can effectively enhance the interface polarization effect and increase the dielectric constant.At the same time,reducing the single layer thickness can reduce the crystallinity of the composite film,which can effectively improve the breakdown field strength and reduce the leakage current density.The dielectric constant of the composite films increases with the decrease of the layer thickness ratio of Al_(2)O_(3)∶HfO_(2).This is mainly due to higher dielectric constant of HfO_(2).But the increase of the leakage current density and the decrease of the breakdown field strength are mainly caused by higher crystallinity of HfO_(2).Furthermore,the finite element model was used to simulate and calculate the relationship between single layer thickness,the composition ratio and the dielectric constant of the composite film.The calculated results are basically consistent with the experimental results.And first-principles calculations were used to prove that there is a built-in electric field at the Al_(2)O_(3)/HfO_(2) interface,which enhances the polarization effect of the dielectric material under the electric field.The interface polarization is the main reason for increament of the dielectric constant of the composite films.

关 键 词：超晶格结构 纳米叠层复合薄膜 介电常数 有限元方法 第一性原理 

分 类 号：TM215.92[一般工业技术—材料科学与工程] O484[电气工程—电工理论与新技术]