Preparation of preferentially oriented thin film interconnect on SiOィイD22ィエD2

Cu interconnect in Si-LSI has been fabricated with a diffusion barrier in the ditch of SiO-D22-D2 by the so-called damascene process。For the Cu interconnect technology， （1） a preferential orientation of Cu （111） plane is desired for suppressing an electromigration failure， and （2） an effective diffusion barrier is also desired as thin as possible。扩散屏障材料，这些问题的满意度，都是在目前的研究中进行的。Transition metal of Nb or V， which is in the bcc structure， is applied as a diffusion barrier between Cu and SiO-D22-D2。The results show that the preferential orientation of Cu （111） is obtained onto the Nb or V（110） oriented barrier formed on the amorphous SiO-D22-D2 layer。The interconnect system with these barriers is found to be difficult to form the thin barrier due to the diffusion of barrier materials through the Cu layer and the reaction at the barrier/SiO-D22-D2 interface。由于薄屏障的形成， NBN或VN被应用于扩散屏障。Thermally stable thin barrier is obtained in the Cu/VN（10 nm）/SiO-D22-D2 system， however， Cu（111） orientation in the system is inior to that using a Nb or V barrier。Ta-W固体解决方案的屏障维护一个bcc结构，然后被应用为一个屏障，在一个更高的系统中。该系统配置实现了Ta-W （110）屏障上的Cu （111）首选方向，并显示出优异的热稳定性，以抑制系统中的Nb或V屏障甚至在20纳米厚的屏障上的扩散和反应。We can achieve the formation of thermally stable thin barrier layer between Cu and SiOD22 y D2 by using Ta-W？y films with a suitable composition。

The Cu interconnect in Si-LSI has been fabricated with a diffusion barrier in the ditch of SiOィイD22ィエD2 by the so-called damascene process. For the Cu interconnect technology, (1) a preferential orientation of Cu (111) plane is desired for suppressing an electromigration failure, and (2) an effective diffusion barrier is also desired as thin as possible. The diffusion barrier materials, which satisfy these issues, are examined in the present study. Transition metal of Nb or V, which is in the bcc structure, is applied as a diffusion barrier between Cu and SiOィイD22ィエD2. The results show that the preferential orientation of Cu (111) is obtained onto the Nb or V(110) oriented barrier formed on the amorphous SiOィイD22ィエD2 layer. The interconnect system with these barriers is found to be difficult to form the thin barrier due to the diffusion of barrier materials through the Cu layer and the reaction at the barrier/SiOィイD22ィエD2 interface. For the formation of thin barrier, NbN or VN is applied to the diffusion barrier. Thermally stable thin barrier is obtained in the Cu/VN(10 nm)/SiOィイD22ィエD2 system, however, Cu(111) orientation in the system is inferior to that using a Nb or V barrier. The barrier of Ta-W solid solution maintaining a bcc structure is then applied as a barrier in the above-mentioned system. This system configuration realizes the Cu (111) preferential orientation on the Ta-W (110) barrier, and shows an excellent thermal stability suppressing the diffusion and reaction observed in the system with Nb or V barrier even at a barrier of 20 nm thick. We can achieve the formation of thermally stable thin barrier layer between Cu and SiOィイD22ィエD2 by using Ta-W alloy films with a suitable composition.