Optimization of Cu interconnects - SiCN interfacial adhesion by surface treatments

Abstract

This paper deals with the interfacial reliability between Cu interconnects and dielectric materials which is a major obstacle to improving the manufacturing yield of memory devices. In order to solve the problems of Cu-SiCN capping layer interface oxidation occurring during the manufacturing process, the interface reliability is improved through surface treatment before SiCN deposition. Here, we compare three different surface treatments using H2, NH3 plasma, and SiH4 gas inflow. A double cantilever beam (DCB) fracture mechanics test is performed to investigate the efficiency of each surface treatment by measuring the quantitative interfacial energy in accordance with the surface treatment. The results denote that the interfacial energy is enhanced by more than 1150% with SiH4gas treatment. Moreover, after DCB test, the delaminated specimens show exclusive and peculiar interfaces. The delaminated surface with SiH4 gas treated indicate an alternating crack path, which determines crack propagation depending on the crystal orientations of Cu substrate. The alternating crack path results from the lower adhesion in Cu (100)-SiCN and Cu (111)-SiCN compared to the other Cu crystal orientations-SiCN. A possible mechanism for the Cu grain-orientation-dependent adhesion is that the degree of Si atom incorporation into Cu surface differs depending on the Cu crystal orientations. We believe that this study can give guidelines for surface treatment methods to improve the mechanical reliability of packaging structure of semiconductors.