A distribution-dependent grain size measurement for the accurate property prediction of ruthenium interconnects

초록

Ruthenium (Ru) is a promising material for next-generation semiconductor interconnects because of its low resistivity scaling and robust electrical reliability. Since Ru lines are patterned from thin films, understanding the relationship between film microstructure and physical properties is essential. This study investigated how grain size measurement methodology influences the correlation between microstructure and two key properties-resistivity and growth stress-in Ru films. Grain size was evaluated via the circle equivalence method (CEM) and linear intercept method (LIM) for as-deposited and annealed films. The results revealed that the optimal grain size metric depends on grain morphology as well as distribution skewness. The LIM better captured the properties of as-deposited films with highly skewed distributions, whereas the CEM was better for annealed films with symmetric distributions. These findings highlight the need to consider distribution characteristics when selecting grain size metrics, offering a framework for accurate property prediction in high-melting-point interconnect metals.

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