关键词: 铜/low-k互连, 应力诱生空洞, 工艺波动, 通孔微结构

Abstract:

Based on the kinematic hardening model of copper,the Cu stress in different Cu/low-k via microstructures are modeled and analyzed via the finite element method to explore the changes of via height,via gouging depth and barrier layer thickness at the via bottom due to the process variation of interconnected via and via barrier layer.Then,the corresponding interconnected via and bottom interconnection stress-induced voiding（SIV） varying with the changes are analyzed.The results indicate that the via microstructure effect of Cu/low-k interconnection is a dominated factor affecting the interconnection stress and the SIV,that the via with high aspect ratio is more susceptible to SIV due to height variation,that the via gouging with suitable depth effectively improves the reliability of stress migration,and that the interconnection SIV performance and the thickness of barrier layer at the via bottom should be compromised because there exists contradiction between the two factors.

Key words: Cu/low-k interconnect, stress-induced voiding, process variation, via microstructure