原子层沉积氮化钽薄膜的研究进展  

Research Progress on Atomic Layer Deposition of TaN x Film

作　　者：乌李瑛 瞿敏妮 付学成[1] 田苗 马玲 王英[1] 程秀兰 WU Liying;QU Minni;FU Xuecheng;TIAN Miao;MA Ling;WANG Ying;CHENG Xiulan(Center for Advanced Electronic Materials and Devices,School of Electronic Information and Electrical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学电子信息与电气工程学院,先进电子材料与器件平台,上海200240

出　　处：《材料导报》2020年第19期19101-19110,共10页Materials Reports

基　　金：国家科技部“十三五”高性能计算重点研发计划项目子课题(2016YFB0200205);2018年度上海研发公共服务平台建设项目(18DZ2295400);上海交通大学决策咨询课题(JCZXSJB2019-005,JCZXSJB2018-022)。

摘　　要：在集成电路中,铜互连工艺需要沉积一层连续且保形性良好的铜阻挡层。氮化钽是一种过渡金属氮化物,由于其硬度高,导电性可控,对金属元素具有扩散阻挡的作用,在微电子工业领域中氮化钽是铜互连技术中研究最为广泛的扩散阻挡层材料。随着集成电路特征尺寸的减小及沟槽深宽比的增加,早期的物理气相沉积(PVD)工艺难以满足其未来的制作需求,因此原子层沉积(ALD)技术对制备超薄氮化钽阻挡层起着至关重要的作用。大部分ALD氮化钽薄膜的工艺优化主要集中在控制前驱体及还原气体的成分和工艺,以避免生成高阻态Ta 3N 5。这是由于器件关键尺寸的持续缩小会导致铜互连体积减小和阻挡层TaN在铜线中所占比例增加,而相比于铜阻挡层材料(TaN电阻率小于0.25 mΩ·cm;Ta 3N 5电阻率约为6Ω·cm),铜的电阻率(1.67μΩ·cm)极低,因此阻挡层在铜互连中所占比例增加必然导致互连线导电性减弱。同时,互连线导电性不好还会导致器件工作信号传输延迟和工作能耗增加,因此,铜阻挡层的厚度应尽量薄。此外,这层极薄的铜扩散阻挡层需要被连续沉积在器件的层间绝缘层(ILD)上,且阻挡层的薄膜不能有任何孔洞,而原子层沉积则是能够同时满足上述条件的薄膜制备技术。对于原子层沉积氮化钽,以钽卤化物或有机钽金属作为前驱体,采用原子层沉积工艺制备的薄膜已得到广泛研究。然而,这些前驱体在原子层沉积过程中会产生腐蚀性副产物,并不适合工业应用。此外,这些前驱体在室温下均为固体,可能导致设备及所沉积薄膜被颗粒污染。因此,学者们开发出醇盐基、酰胺基等金属有机前驱体用于薄膜的制备。研究表明,钽的醇盐类前驱体通常含有氧元素,会使原子层沉积的氮化钽有较高的氧残留;而使用酰胺基或酰亚胺基前驱体则可以制备出氧杂质含量较少的薄膜,但其热稳�For the copper interconnect process in microelectronics,it requires to deposit a continuous and well-shaped copper barrier layer.Tantalum nitride is a transition metal nitride and acts as diffusion barrier to metal interconnect,due to its high hardness and controllable electrical conductivity.In the microelectronics industry,tantalum nitride is one of the most widely studied diffusion barrier materials in copper interconnection technology,with the decrease of critical dimension for integrated circuit and the increase of aspect ratio,the early PVD process is difficult to meet future production requirements,thus atomic layer deposition technique plays a crucial role for ultra-thin tantalum nitride barrier layer.The process optimization of most ALD tantalum nitride thin films is mainly focused on controlling the composition and process of precursor and reducing agent to avoid the formation of high-resistance Ta 3N 5.With the continuous decrease of the feature size of circuit devices,the proportion of TaN barrier layer to Cu metal is also decreasing due to the limited dimension of interconnect line.Considering the significantly lower resistivity(1.67μΩ·cm)of Cu interconnect lines relative to those of Cu barrier materials.The resistivity of TaN is lower than 0.25 mΩ·cm,and the resistivity of copper is extremely low(1.67μΩ·cm),this can result in poor conductivity of the entire interconnect.As the high resistivity of the interconnect line eventually leads to delays in working signal transmission,as well as high power consumption of device,the thickness of Cu barrier layer should be minimized.In addition,the extremely thin copper diffusion barrier layer is required to be deposited continuously on the interlayer insulator layer(ILD)of the device.Atomic layer deposition technology can meet these conditions simultaneously.For the atomic layer deposition of tantalum nitride,the tantalum halide or tantalum metal organic is used as the precursor,and the film prepared by the atomic layer deposition process has been exte

关 键 词：TaN薄膜 原子层沉积 等离子增强型原子层沉积 电阻率 铜阻挡层 

分 类 号：TB34[一般工业技术—材料科学与工程]