Interfacial intermixing of TiN/Si3N4 super-hard multilayer films studied by fluorescence x-ray absorption fine structure

Fluorescence x-ray absorption fine structure and x-ray diffraction are used to study the structures of super-hard TiN/Si3N4 multilayer films deposited by reactive magnetron sputtering at temperatures of 20, 200, 500 and 800 degrees C. The results clearly reveal the presence of interfacial intermixing between adjacent TiN and Si3N4 layers. And the interlayer is composed of TiSixN1-x solid solution with an NaCl-like structure. Increasing the growth temperature from 20 to 500 degrees C, the crystalline quality of the pure TiN layer improves significantly, and the thickness of the interlayer rises from 2.5 to 5.0 angstrom. For the TiN/Si3N4 multilayer film grown at 500 degrees C, the interfacial layer is composed of TiSi0.24N0.76 solid solution, where the Ti-N bond length (2.07 angstrom) is largely shrunk as compared with the value (2.12 angstrom) in the pure TiN layer. When growth temperature rises to 800 degrees C, the composition of the interfacial layer becomes TiSi0.3N0.7 and reaches a thickness of 7.8 angstrom. We propose that the TiSixN1-x interlayer with obviously contracted Ti-N bond length is an important hardening factor for the crystalline/amorphous TiN/Si3N4 multilayer films grown at high temperatures.