Quantitative depth-profile analysis of transition metal nitride materials with combined grazing-incidence X-ray fluorescence and X-ray reflectometry analysis

Abstract

Refractory transition metal nitrides are attracting attention in many microelectronics research and development fields. Their different applications and desired performances require a precise control of the film thickness and elemental depth profile. This information can be non-destructively obtained combining Grazing-Incidence X-ray Fluorescence (GIXRF) and X-ray Reflectometry (XRR) analysis. GIXRF-XRR joint analysis can be performed following a reference-free approach, which requires the knowledge of the whole experimental system. However, such a rigorous metrological approach cannot be easily applied to in-lab or in-fab tools due to the difficulty to access the various experimental set-up parameters, therefore another approach is needed.In this paper, we used a reference-based method consisting in the use of known standard samples, close in composition and structure with respect to the samples to analyse, to deduce the key parameters of the instrumental setup. These are then used to perform quantitative GIXRF-XRR combined analysis of the samples of interest. We applied this method to titanium tungsten nitride thin films elaborated by Physical Vapour Deposition (PVD). Our results show that the reference-based method, using carefully determined instrumental functions, can meet the requirement for both qualitative and quantitative depth-profiling analysis. The reference-based approach result easier to implement into labs and fabs than the reference-free method.