EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Cu is a common metallization material in integrated circuits due to its low resistivity. However, it shows a low adhesion to the dielectric layer and reacts with Si reducing the lifetime of the device. To improve the adhesion and chemical stability, an interlayer such as WTi is needed. The interfacial and mechanical properties of the Cu-WTi system have not been studied in detail and need further research.

We present results on the adhesion properties of Cu-W and of Cu-WTi layered systems. We analyze the segregation behavior of common technical elements and their effect on interface adhesion. The interfaces are based on the Kurdjumov-Sachs and Nishiyama-Wassermann orientation relationships. The adhesion of Cu-W is compared to Cu-WTi and the impact of Ti is discussed. The segregation behavior and the preferred segregation sites of common technical elements are analyzed and compared to the segregation behavior in pure Cu and W. Finally, we discuss the strengthening and weakening effect of segregants on the cohesive strength of the interface and its implications for alloying and impurities. The results contribute to an improved understanding of the cohesive properties of the Cu-WTi system and provide guidelines for a controlled engineering of the Cu-WTi interface to increase its mechanical stability.