Mechanical properties study of W/TiN/Ta system multilayers

In the present work, W/TiN/Ta system multilayers are developed and compared with W/Ta multilayers through three point bending and tensile tests. W/TiN/Ta, especially W/TiN(Ti)/Ta multilayers have much higher strength than that of W/Ta multilayers due to the intrinsic high strength of TiN and the increased layered interfaces, while with less ductility. W/TiN/Ta and W/TiN(Ti)/Ta with tTa/W = 1 also exhibit multiple cracks propagation characteristic as W/Ta, while the fracture characteristics are similar to that of W/Ta multilayers with smaller tTa/W due to lower interface strength. The plastic deformation and bridging effect of Ta layer are smaller; the interface cracking is much more intense; and more micro-cracks generated under load in these two multilayers. Their DBTT by tensile test is all about 300 °C, the ductility of W/Ta is better than W/TiN/Ta and W/TiN(Ti)/Ta above 300 °C, and reaches 37% at 400 °C, while the ductility of W/Ta decreases dramatically during 400-700 °C due to oxidation. At the whole temperature range, the ductility of W/TiN/Ta and W/TiN(Ti)/Ta is close, and keeps highest during 400-600 °C, which is about 12%. The interface of W/TiN/Ta system multilayers can be protected from serious oxidation by TiN coating at high temperature.