Relationship between the electron system and the diffusion of hydrogen atoms in Si3N4 layers

Abstract

In this article, the diffusion of hydrogen in Si3N4 films and its relation with the electron system of the dielectric layer are investigated. The study was carried out on structures consisting of a dielectric substrate and a layer of poly-Si or (poly-Ge). Using FTIR spectroscopy, it has been shown that the transition of hydrogen atoms from the Si3N4 layer to the growing poly-Si (poly-Ge) layer depends on the content of electrically active boron atoms and can be blocked at its high value. We assume that the diffusion mechanism of hydrogen atoms in Si3N4 is the same as in poly-Si and is associated with the rupture of Si–Si bonds and the formation of a Si–H–Si defect. Si–Si bonds are traps for carriers (holes) in Si3N4. The influence of electrically active boron atoms in the poly-Si (poly-Ge) film on hydrogen atom diffusion can be explained by the transfer of charge carriers (holes) from the semiconductor to the levels of Si–Si traps in the bandgap of the dielectric with the formation of (Si–Si)+ charged centers. Since hydrogen diffuses mainly as H+ ions in poly-Si (poly-Ge) films, these charged centers block its penetration into the poly-Si (poly-Ge) film. All the above processes occur during the growth of poly-Si (poly-Ge) films in the absence of an external electric field.