Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Non - ferrous metals and their alloys > Heavy non - ferrous metals and their alloys

Microstructure and Stress of ULSI Cu Interconnects and Their Impacts on Electromigration

Author WangXiaoDong
Tutor JiYuan
School Beijing University of Technology
Course Materials Science
Keywords Copper interconnect lines Microstructure Stress Electromigration
CLC TG146.1
Type Master's thesis
Year 2003
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In this thesis, the microstructure and stress of ULSI in copper interconnect lines and electromigration MTF . AFM, SEM and TEM evaluation grain structure . By the recess sidewall nucleation of copper interconnect lines deposited with the increase in the linewidth , the average grain size was increased from 20 ~ 30nm 80 ~ 90nm, the grain size of the copper film is approximately 300nm; 3μm copper interconnect lines the grain size of the intermediate region is smaller than the grain size of the sidewalls ; after annealing, the grain growth of the copper interconnect lines , and the degree of grain growth is increased with the increase in the linewidth . XRD and EBSD measurements of the crystallographic orientation of the copper interconnect lines the deposited copper interconnect lines (111) texture significantly weaker than the deposited copper film ; 300 ° C , 30min annealed copper interconnect lines (111) structure enhancements ; Cu grains are obviously grew up and strain can be minimized so that the copper interconnects and copper film after a high temperature of 400 ℃ and 450 ℃ , 1h after annealing , the ( 111 ) texture did not develop . SiON and a Ta diffusion barrier layer by SIMS and AES analysis results show that the two blocking layer can effectively prevent the diffusion of copper to the SiO2 layer . The two-dimensional surface detection XRD results show that the tensile stress of the deposited copper interconnect lines , mainly by thermal stress . After annealing at 200 ℃ , copper interconnects tensile stress relaxation. The 1,2 and 4μm wide copper interconnect lines MTF increases with increasing linewidth . MTF and activation energy is higher than the deposited samples annealed copper interconnect lines grain growth and (111) texture enhanced . 4μm copper interconnect electromigration failure mainly of copper along the grain boundary diffusion; as the linewidth decreases , the diffusion of copper along the sidewall of Cu / Ta / SiO2 interfaces become electrically migration of copper interconnect lines 1 and 2 μm the main reason of the failure .

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