Significantly enhanced bonding strength in Al2O3/HfO2 using nanolaminate interfaces

The interface plays a crucial role in the mechanical behavior of layered and gradient-structured materials. However, interfaces between different materials are prone to sliding and cracking, leading to structural failure. In this study, two film structures, Al2O3 (61 nm)/HfO2 (75 nm) and Al2O3 (43 nm)/Al2O3+HfO2 nanolaminate (69 nm)/HfO2 (24 nm), were prepared using atomic layer deposition. The Al2O3 + HfO2 nanolaminate consists of alternating nanometric layers of Al2O3 and HfO2, for a total of 20 layers. Through tensile tests, it is demonstrated that the bonding strength at the interface between Al2O3 and HfO2 films was separated, which is around 6.58 MPa. In contrast, for the samples using a nanolaminate structure, the bonding strength is significantly improved and exceeds 15.54 MPa. Based on the results of X-ray photoelectron spectroscopy and secondary ion mass spectrometry, we propose a model for nanoscale bonding strength between different materials. The analysis of the results of transmission electron microscopy also validates the rationality of this model, and the inherent physical mechanisms for enhancing bonding strength in the nanolayered structure were analyzed from the perspective of force field coupling. This provides new insights into improving the stability of microdevices and the bonding of materials.