Ultra-thin film and interface analysis of high-k dielectric materials employing Time-Of-Flight Medium Energy Ion Scattering (TOF-MEIS)

TL;DR

This paper demonstrates the use of Time-Of-Flight Medium Energy Ion Scattering (TOF-MEIS) to analyze ultra-thin high-k dielectric films, providing detailed depth profiles and film quality assessments.

Contribution

It introduces TOF-MEIS as an effective technique for analyzing ultra-thin high-k dielectric stacks and discusses associated challenges and solutions.

Findings

Successful depth profiling of HfO2 films from 1.8 to 12.2 nm

Identification of composition and stoichiometry in ultra-thin films

Complementary use of RBS for areal density measurement

Abstract

We explore the potential of Time-Of-Flight Medium Energy Ion Scattering (TOFMEIS) for thin film analysis and analyze possible difficulties in evaluation of experimental spectra. Issues regarding different combinations of composition and stopping power as well as the influence of channeling are discussed. As a model system high-k material stacks made from ultra-thin films of HfO2 grown on a p-type Si (100) substrate with a 0.5 nm SiO2 interface layer have been investigated. By comparison of experimental spectra and computer simulations TOF-MEIS was employed to establish a depth profile of the films and thus obtaining information on stoichiometry and film quality. Nominal film thicknesses were in the range from 1.8 to 12.2 nm. As a supporting method Rutherford-Backscattering spectrometry (RBS) was employed to obtain the areal density of Hf atoms in the films.