ULSI中Cu互连线的显微结构及可靠性

观察了ULSI中大马士革结构的Cu互连线的晶粒生长和晶体学取向.分析了线宽及退火对Cu互连线显微结构及电徙动的影响.Cu互连线的晶粒尺寸随着线宽的变窄而减小.与平坦Cu膜相比,Cu互连线形成微小的晶粒和较弱的 (111) 织构.300℃、30min退火促使Cu互连线的晶粒长大、(111) 织构发展,从而提高了Cu互连线抗电徙动的能力.结果表明,Cu的扩散涉及晶界扩散与界面扩散,而对于较窄线宽的Cu互连线,界面扩散成为Cu互连线电徙动失效的主要扩散途径.

Microstructure and Reliability of ULSI Copper Interconnects

The grain growth and crystallographic orientation of the ULSI Cu interconnects within the Dmascene architecture were observed.Microstructures of the Cu interconnect depending on linewidths and anneal temperatures and impacts on the electromigration (EM) were analyzed.The grain size of Cu lines shrinked as the linewidth was reduced.The small grains and the weaker (111) texture in Cu lines were formed compared with that in Cu blanket films.The EM resistance of the Cu metallization could be improved via the grain growth and the (111) texture developed during anneal at 300℃ for 30min.The results indicate that the Cu diffusion involves interface diffusion and boundary diffusion, while the diffusion along interface plays a dominant role in EM failure for Cu lines with the narrow linewidth.