Probing Cu Diffusion Barrier Layers on Porous Low-Dielectric-Constant Films by Posireonium Annihilation Lifetime Spectroscopy  

作　　者：胡一帆 SUN Jia-Ning Gidley D.W. 

机构地区：[1]Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 [2]Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA

出　　处：《Chinese Physics Letters》2005年第11期2906-2909,共4页中国物理快报（英文版）

基　　金：Supported partially by the National Natural Science Foundation of China under Grant No 60476011.

摘　　要：Two kinds of Cu diffusion barrier layers, sealed films and capped films, on nanoporous low-dielectric-constant films are investigated by positronium annihilation lifetime spectroscopy （PALS）. We have found that the minimum thickness of Ta to form an effective diffusion barrier is affected by the pore size. The films with large pores require thick barrier layers to form effective diffusion barriers. In addition, a possible ultra-thin diffusion barrier, i.e. a plasma-induced densification layer, has also been investigated. The PALS data confirm that a porous low-dielectric-constant thin film can be shrunk by exposure to plasma. This shrinkage is confined to a surface layer of collapsed pores and forms a dense layer. The dense layer tends to behave as Ps （positronium） diffusion barriers. Indeed, the controlled thin “skin” layer could prevent Cu diffusion into the underlying dielectrics.Two kinds of Cu diffusion barrier layers, sealed films and capped films, on nanoporous low-dielectric-constant films are investigated by positronium annihilation lifetime spectroscopy （PALS）. We have found that the minimum thickness of Ta to form an effective diffusion barrier is affected by the pore size. The films with large pores require thick barrier layers to form effective diffusion barriers. In addition, a possible ultra-thin diffusion barrier, i.e. a plasma-induced densification layer, has also been investigated. The PALS data confirm that a porous low-dielectric-constant thin film can be shrunk by exposure to plasma. This shrinkage is confined to a surface layer of collapsed pores and forms a dense layer. The dense layer tends to behave as Ps （positronium） diffusion barriers. Indeed, the controlled thin “skin” layer could prevent Cu diffusion into the underlying dielectrics.

关 键 词：THIN-FILMS 

分 类 号：O484.41[理学—固体物理]