Stress development and relaxation in copper films during thermal cycling
Stress development and relaxation in copper films during thermal cycling
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DOI：
10.1557/jmr.1993.1845
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发表时间：
1993-08
影响因子：
2.7
通讯作者：
M. Thouless;J. Gupta;J.M.E. Harper
中科院分区：
文献类型：
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作者：
M. Thouless;J. Gupta;J.M.E. Harper
集成电路布线的可靠性在很大程度上取决于应力的发展和松弛，应力促进空洞和小丘的形成。在本文中，现有的蠕变模型的基础上提出的分析，预测在薄毯膜的铜在Si晶片上进行热循环的应力。结果描绘变形机制图，确定预计在热循环过程中运行的主导机制。这些预测与温度梯度和等温应力测量1 μ m厚的溅射Cu膜在25-450 °C的温度范围内进行了比较。该模型成功地预测了应力松弛的速率，当薄膜保持在一个恒定的温度和热循环过程中产生的应力-温度滞后。对于在25-450 °C的温度范围内循环的1 μ m厚的Cu膜，变形图表明，当膜中只能维持低应力时，晶界扩散控制了较高温度（>300 °C）下的应力释放，幂律蠕变在中间温度下是重要的，并且决定了最大压应力，如果位错滑移屈服（低温塑性）发生，它只会在最低温度（<100 °C）下发生。这最后一种机制在本项目研究的电影中似乎没有发挥作用。
The reliability of integrated-circuit wiring depends strongly on the development and relaxation of stresses that promote void and hillock formation. In this paper an analysis based on existing models of creep is presented that predicts the stresses developed in thin blanket films of copper on Si wafers subjected to thermal cycling. The results are portrayed on deformation-mechanism maps that identify the dominant mechanisms expected to operate during thermal cycling. These predictions are compared with temperature-ramped and isothermal stress measurements for a 1 μm-thick sputtered Cu film in the temperature range 25–450 °C. The models successfully predict both the rate of stress relaxation when the film is held at a constant temperature and the stress-temperature hysteresis generated during thermal cycling. For 1 μm-thick Cu films cycled in the temperature range 25–450 °C, the deformation maps indicate that grain-boundary diffusion controls the stress relief at higher temperatures (>300 °C) when only a low stress can be sustained in the films, power-law creep is important at intermediate temperatures and determines the maximum compressive stress, and that if yield by dislocation glide (low-temperature plasticity) occurs, it will do so only at the lowest temperatures (<100 °C). This last mechanism did not appear to be operating in the film studied for this project.