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研究了40 nm工艺中低阻值接触栓的电迁移性能的提升。高性能芯片要求接触栓电阻尽可能小,而接触栓尺寸的减小使低电阻率钨成为必然选择。新材料的引入和尺寸减小等因素使传统工艺中较为稳定的接触栓的电迁移可靠性面临新的挑战。通过减少电化学腐蚀、改善金属填充、强化界面结合力及减少应力失配等,形成综合性解决方案。最终封装级电迁移可靠性测试结果为:激活能Ea为0.92 eV,电流密度指数n为1.12,寿命为86.3年(超过10年的标准)。与最初工艺相比,消除了顶部腐蚀和中心空隙的缺陷形貌,接触栓电阻优于设计标准,抗电迁移寿命提高超过一千万倍,极大地提高了接触栓的电迁移性能。
The electromigration performance of low-resistance contact plugs in 40 nm process was studied. High-performance chips require contact resistance as small as possible, while reduction in contact size makes low-resistivity tungsten an inevitable choice. The introduction of new materials and the reduction of size make the electromigration reliability of the more stable contact plug in the traditional process face new challenges. Through the reduction of electrochemical corrosion, improve the metal filling, strengthening the interface binding and reduce stress mismatch, a comprehensive solution. The final package-level electromigration reliability test results were: activation energy Ea of 0.92 eV, current density index n of 1.12, and lifetime of 86.3 years (over a 10-year standard). Compared with the original process, the top corrosion and the center void are eliminated. The contact plug resistance is better than the design standard, and the anti-electromigration lifetime is increased by more than ten million times, greatly improving the electromigration performance of the contact plug.