【作者】 张海燕；

【导师】 宁兆元； 叶超；

【作者基本信息】 苏州大学 ， 凝聚态物理， 2008， 硕士

【摘要】 为了解决超大规模集成电路的特征线宽不断减小而导致的互连阻容耦合增大、信号传输延时、功耗增大等问题,多孔超低介电常数（超低k）的SiCOH材料应运而生,成为人们研究的焦点,其中通过引入孔隙来降低SiCOH薄膜密度成为降低介电常数的有效途径。但是过多孔隙的引入会导致材料的力学性能下降、吸湿性能与污染增强等问题。近年来人们正在探索将弱极化键和孔隙相结合,在较低孔隙率的条件下获得性能优异的SiCOH低k薄膜。由于薄膜的结构、性能与沉积薄膜时的放电等离子体中基团状态密切相关,因此对SiCOH低k薄膜沉积过程的等离子体化学特性开展研究,是低k薄膜研究的一个重要方面。但是,目前在SiCOH薄膜放电等离子体化学方面的研究工作还较少,研究内容不够深入。本文以F-SiCOH薄膜沉积过程的等离子体化学研究为目标,通过分析沉积SiCOH薄膜的前驱气体十甲基环五硅氧烷（DMCPS）在电子碰撞下的离化机理、DMCPS在电子回旋共振（ECR）等离子体中的离化行为、以及CHF₃/DMCPS在ECR等离子体中的离化行为,给出了CHF₃/DMCPS在ECR放电条件下可能的反应途径,分析了放电等离子体对于F-SiCOH薄膜结构的影响。结果表明在电子碰撞下,DMCPS发生开环断裂反应,部分SiO链重排成环而形成三元SiO环结构和SiO相关离子,侧链甲基从Si上脱离。在ECR等离子体中,DMCPS开环断裂反应产生的SiO环链进一步交联,生成Si-O-Si鼠笼结构,从而形成本构孔隙。当DMCPS中加入CHF₃后,在ECR等离子体中,CHF₃/DMCPS离化产生的基团除了与DMCPS相关的SiO、CH_x（x=1,2,3）基团和与CHF₃相关的基团外,还出现了SiF、SiF₃、SiFC₂H₂等新的基团。同时在薄膜中形成SiF、CF、（CH₂）_n等弱极性化学键,这些弱极性键的引入有利于平衡高孔隙率带来的材料的力学性能下降、吸湿性能与污染增强等负面影响。更多还原

【Abstract】 In order to solve the problems caused by device-dimension continuous shrinking in ultmlarge-scale integrated chips,such as signal propagation delay,power consumption,and the cross-link between metal interconnects,porous ultralow dielectric constant（k＜2）SiCOH film have received close attention.The decrease of film density by introducing pores into film can reduce dielectric constant of SiCOH film effectively.If too many pores are introduced in the film,however,it will cause some problems such as bad mechanic property,the increase of hydrophilic property and contamination.To overcome these problems,a combination of weak polar bonds with lower density pores to prepare low-k materials has drawn attention.F doping SiCOH film is a kind of low-k material composed by weak polar Si-F bonds and Si-O cages.Due to the structure and properties of films depends on the intermediate gas phase in the plasma,the investigation on the plasma chemistry during the deposition of SiCOH film is one of the most important issues.This paper investigates the fragmentation behavior of decamethylcyclopentasiloxane（DMCPS）by electron impact and in electron cyclotron resonance plasma,and of CHF₃/DMCPS mixtures in ECR plasma using a quadrupole mass spectrometry,which is used as the precursors to deposit F-SiCOH film. Combined with the bonding configuration of F-SiCOH films,the relation between species in ECR plasma and films structures is analyzed.The results show that the main fragmentation behavior of DMCPS includes two stages.One is the broken of fivefold Si-O ring and then the formation of threefold Si-O ring and Si-O chain species.The other is the lost of hydrocarbon groups from Si atoms.In ECR discharge plasma,SiO tings crosslink with SiO chains and further form Si-O-Si cage structures.The cage structure is of advantage to the decreasing of film dielectric constant.For the CHF₃/DMCPS ECR plasma,some new radicals,such as SiF,SiF₃,SiFC₂H₂,occur except the SiO、CH_x（x=1,2,3）from the dissociation of DMCPS and the radicals from CHF₃ dissociation.Meanwhile,the weak polar bonds,such as SiF、CF、（CH₂）_n,form in the F-SiCOH film.The incorporation of these weak polar bonds into the film is of advantage to improving the problems,such as bad mechanic property.更多还原