Thickness monitoring of sub-nanometer scale La2O3 films using total X-ray reflection fluorescence spectrometry

Abstract

Due to the recent acceleration on device shrinkage in the semiconductor industry, gate oxide materials like silicon dioxide are being substituted by high-k dielectrics. Unfortunately, the poly-silicon gate and high-k dielectrics react, leading eventually to pinning effects. Consequently, there is a great demand to use metal oxides such as La₂O₃ in order to prevent these effects. It is very important that the thickness is ultra-thin and constantly controlled. In this regard, this paper introduces a method to measure the thickness of sub-nanometer scale La₂O₃ films using Total X-Ray Reflection Fluorescence Spectrometry (TXRF). The results confirm the applicability of monitoring the thickness of sub-nanometer scale La₂O₃ films in the deposition process by TXRF.