Determination of density profile of ultrathin SiO2/Si3N4/SiO2/Si(001) multilayer structures using x-ray reflectivity technique

Abstract

In this report, we present an analysis of a SiO2/Si3N4/SiO2/Si(001) ultrathin multilayer structure using the x-ray reflectivity technique. The trilayer was grown using low-pressure chemical vapor deposition with each layer having a nominal thickness of ∼50 Å. Here, we propose an approach to analyze ultrathin multilayer films using two analysis schemes in tandem, i.e., distorted wave Born approximation and exact recursive formalism for x-ray reflectivity. We observe that, when SiO2 is deposited on a Si substrate, the electron density is lower than when it is deposited on Si3N4. We also observe that the two interfaces of the nitride (Si3N4) film are different, i.e., the interfacial width with the lower SiO2 is larger than the width with the top SiO2 layer.