半导体铜布线阻挡层技术的研究
发布时间：2018-11-28 09:12
【摘要】：半导体工艺中特征尺寸的日渐减小,使得集成电路互连线的有效电流承载密度逐渐增大,电迁移问题越来越明显,极大地影响到半导体器件的稳定性,传统的Al互连系统已经难以满足集成电路快速发展的性能需求,而Cu以其低电阻率、优良的抗电迁移性能,逐渐取代Al,成为当前应用最广泛的互连金属。然而,Cu在Si衬底及其氧化物中非常容易发生扩散,Cu金属进入Si器件中会成为深能级受主杂质,形成高电阻率的化合物,使得电路系统的漏电流增大,半导体器件的性能退化甚至失效;另外,Cu与Si、SiO2等材料接触结合力较差,且在空气中易发生氧化,致使互连线电阻率增大。所以,必须在Cu金属与半导体衬底间加一层可以有效阻止两者相互扩散的阻挡层材料。研究电阻率低,可靠性高,性能优良的扩散阻挡层,并以阻挡层+铜互连金属的膜系结构作为互连系统是集成电路快速发展的重要方向,也是本课题主要的研究内容。本文选用的扩散阻挡层是以氮化钬薄膜为基础的复合膜层,辅以Ti单金属层作为过渡层,增加互连系统各层之间的结合力,降低接触电阻。Cu、Si分别作为互连金属和半导体衬底,以磁控溅射作为主要工艺。深入地研究了膜系结构、磁控溅射制备工艺、退火条件对互连系统性能的影响,并且研究了氮化钛作为阻挡层的作用机制,其在高温环境下的失效机理。制备了完整的Cu基半导体金属化布线系统,研究互连系统与Si直接接触的结果,为Cu互连工艺的实际应用提供可靠的实验数据。本课题的主要工作和成果如下:1,分析研究了Cu互连系统的扩散机制与失效机制,研究了不同溅射工艺对阻挡效果的影响,设计并制备出Ti(15 nm)/TiN(25 nm)/Ti(15 nm)的复合膜系结构作为阻挡层。测试结果证明,这种复合阻挡层的最高失效温度可达900℃,稳定性极好。2,以磁控溅射技术为主要工艺,设计并制备出结构为TiN/Cu/Ti/TiN/Ti/Si的完整的Cu互连系统,采用XRD,四探针等测试设备,分析表征该Cu互连系统的稳定性、电阻率等性能。该Cu互连系统能够在同一真空周期内一次性完成制作,可操作性好,具有产业化应用价值。3,分别在n型和p型Si上制备了 TiN(20 nm)/Ti(15 nm)/Si结构的薄膜样品,结合退火工艺,深入研究了退火对金属Ti与n、p型Si之间接触结果的影响,并测量阻挡层以及互连系统的方块电阻。测试结果表明,Ti金属层与p型Si,n型Si均可以形成欧姆接触。
[Abstract]:With the decrease of characteristic size in semiconductor process, the effective current carrying density of integrated circuit interconnects increases gradually, and the problem of electromigration becomes more and more obvious, which greatly affects the stability of semiconductor devices. Traditional Al interconnection systems have been difficult to meet the rapid development of integrated circuit performance requirements, and Cu with its low resistivity, excellent resistance to electromigration, gradually replaced Al, as the most widely used interconnect metal. However, Cu diffuses easily in Si substrates and their oxides. Cu metal entering into Si devices becomes a deep level acceptor impurity, forming compounds with high resistivity, which increases leakage current of circuit system. The performance of semiconductor devices degenerates or even fails; In addition, the contact adhesion between Cu and Si,SiO2 is poor, and it is easy to be oxidized in air, which leads to the increase of interconnect resistivity. Therefore, a layer must be added between the Cu metal and the semiconductor substrate to effectively prevent the diffusion between the two materials. The study of diffusion barrier layer with low resistivity, high reliability and excellent performance is an important direction of the rapid development of integrated circuit, and it is also the main research content of this subject. The film system structure of copper interconnect metal in the barrier layer is the important direction of the rapid development of integrated circuit. The diffusion barrier layer selected in this paper is a composite film based on holmium nitride film, supplemented by Ti single metal layer as the transition layer, which increases the adhesion between the layers of the interconnection system and reduces the contact resistance. Cu,. Si is used as interconnect metal substrate and semiconductor substrate respectively, and magnetron sputtering is the main technology. The effects of film structure, magnetron sputtering technology and annealing conditions on the properties of interconnect system were studied. The mechanism of titanium nitride as a barrier layer and its failure mechanism at high temperature were also studied. A complete Cu based semiconductor metallized wiring system was prepared, and the results of direct contact between the interconnection system and Si were studied, which provided reliable experimental data for the practical application of Cu interconnection technology. The main work and achievements are as follows: 1. The diffusion mechanism and failure mechanism of Cu interconnection system are analyzed, and the influence of different sputtering processes on the barrier effect is studied. The composite membrane structure of Ti (15 nm) / TiN (25 nm) / Ti (15 nm) was designed and fabricated as the barrier layer. The test results show that the maximum failure temperature of the composite barrier layer can reach 900 鈩，
本文编号：2362426
[Abstract]:With the decrease of characteristic size in semiconductor process, the effective current carrying density of integrated circuit interconnects increases gradually, and the problem of electromigration becomes more and more obvious, which greatly affects the stability of semiconductor devices. Traditional Al interconnection systems have been difficult to meet the rapid development of integrated circuit performance requirements, and Cu with its low resistivity, excellent resistance to electromigration, gradually replaced Al, as the most widely used interconnect metal. However, Cu diffuses easily in Si substrates and their oxides. Cu metal entering into Si devices becomes a deep level acceptor impurity, forming compounds with high resistivity, which increases leakage current of circuit system. The performance of semiconductor devices degenerates or even fails; In addition, the contact adhesion between Cu and Si,SiO2 is poor, and it is easy to be oxidized in air, which leads to the increase of interconnect resistivity. Therefore, a layer must be added between the Cu metal and the semiconductor substrate to effectively prevent the diffusion between the two materials. The study of diffusion barrier layer with low resistivity, high reliability and excellent performance is an important direction of the rapid development of integrated circuit, and it is also the main research content of this subject. The film system structure of copper interconnect metal in the barrier layer is the important direction of the rapid development of integrated circuit. The diffusion barrier layer selected in this paper is a composite film based on holmium nitride film, supplemented by Ti single metal layer as the transition layer, which increases the adhesion between the layers of the interconnection system and reduces the contact resistance. Cu,. Si is used as interconnect metal substrate and semiconductor substrate respectively, and magnetron sputtering is the main technology. The effects of film structure, magnetron sputtering technology and annealing conditions on the properties of interconnect system were studied. The mechanism of titanium nitride as a barrier layer and its failure mechanism at high temperature were also studied. A complete Cu based semiconductor metallized wiring system was prepared, and the results of direct contact between the interconnection system and Si were studied, which provided reliable experimental data for the practical application of Cu interconnection technology. The main work and achievements are as follows: 1. The diffusion mechanism and failure mechanism of Cu interconnection system are analyzed, and the influence of different sputtering processes on the barrier effect is studied. The composite membrane structure of Ti (15 nm) / TiN (25 nm) / Ti (15 nm) was designed and fabricated as the barrier layer. The test results show that the maximum failure temperature of the composite barrier layer can reach 900 鈩，
本文编号：2362426
本文链接：https://www.wllwen.com/kejilunwen/dianzigongchenglunwen/2362426.html
