Strain Study of Nb-Si{001} Interface Based on Geometric Phase Analysis

Abstract

High resolution electron microscopy imaging and geometric phase analysis were employed to study the microstructure and strain states of Nb/Si interface prepared at different sputtering pressures. The results show that the surface of Nb thin film consists of petals-shape lamellas with random morphological distribution and no obvious characteristic orientation. The size of the lamella increases and the density of the lamella decreases with the increase of deposition pressure； meanwhile, a large number of pores appear on the surface of Nb film and a mixed layer of Nb and Si is generated between Nb film and Si substrate. When Nb films were deposited at 0.65, 0.85 Pa and 1 Pa, the strain values of εxx were respectively –0.16%, –0.30% and 0.42%; the strain values of εyy were respectively –1.23%, –0.31% and 0.26%.The strain states of Si substrate are tremendously influenced by the disposition pressure. The strain states of Si substrate are mainly produced by the effect of the interfacial mixed layer and Nb thin film. A large number of structure defects are generated in the mixed layer of Nb and Si, which produces intrinsic stress in the mixed layer, and further results in the formation of strain in Si substrate.

Keywords

• high-resolution imaging
• geometric phase analysis
• Nb thin film
• Si substate
• mixed layer
• strain