金属互连电迁移噪声的相关维数研究

Research on noise correlation dimension of metallic interconnection electromigration

针对金属铝互连中噪声信号随电迁移过程变化规律及其所反映的内部失效机理问题,提出将相关维数用于对电迁移噪声时间序列的分析.通过对互连电迁移噪声实验数据的相关维数计算,发现随着电迁移的进行,金属铝互连噪声由随机性成分占主导变为确定性成分占主导,反映出噪声由随机信号转变为混沌动力学信号.应用散射理论解释上述现象,在金属互连电迁移中,空位扩散阶段噪声主要产生机制是空位随机散射;在空位聚集到空洞成核这一过程中,噪声产生机制逐渐从随机散射转变到弹道混沌腔输运机制为主.通过与传统表征参量的对比,证明相关维数可用于预测金属互连的电迁移失效.

In order to describe the change of noise signal in A1 thin-film during electromigration process and its invalidation mechnism, correlation dimension was used in the electromigration noise signal analysis. Through calculating ＇correlation dimension of electromigration noise signals attained by our experiment, the result showed that the main component of noise signal changed from stochastic to determinate during electromigration process, indicating that the noise changed from stochastic signal to chaotic dynamic signal. Dispersion theory was used to explain the above phenomenon. During vacancy dispersion, the main cause of noise is the stochastic dispersion of vacancies; during the process of vacancies accumulation to void nucleation, the main cause of noise is the change from stochastic dispersion to ballistic chaotic cavity transport. Compared with traditional parameters, the result showed that correlation dimension could be used to predict the invalidation of electromigration damage.