The Poison effect on Cu Electromigration Degradation

• Main Authors: Han-Yi Hung, 洪漢儀
• Other Authors: Bi-Shiou Chiou
• Format: Others
• Language: en_US
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/87513690852724761851

碩士 === 國立交通大學 === 電子工程系 === 87 === The use of low resistivity conductors and low dielectric constant interlevel dielectrics has been proposed to reduce the RC time delay and to improve electromigration (EM) damage. In this work, the metallization system with Cu and low K material, polyimide (PI), was prepared for electromigration tests. TGA, DTA and DSC revealed the thermal stability of polyimide and FTIR revealed the chemical structure transformation of polyimide in thermal process. Poison effect was observed during curing of polyimide and was investigated by secondary ion mass spectrometer (SIMS). It is observed that poison effect degraded the electric property of copper line and enhanced electromigration damage (EMD). Hence, a layer of thin SiO2 as diffusion barrier was deposited between polyimide and Cu in order to reduce poison effect. Electromigration of Cu interconnection was studied by an isothermal electrical resistance method. Electromigration of copper line with polyimide/SiO2, polyimide and SiO2 as passivation layers had been proposed to inhibit oxidation during high temperature electromigration measurement. As current density was below 2x106A/cm2, the raising temperature resulted from joule heating was too small to induced thermomigration. The activation energy and the mechanisms of electromigration were discussed. Keyword: Electromigration, Poison effect, Thermomigration,