Quantification of High Resolution Pulsed RF GDOES Depth Profiles for Mo/B4C/Si Nano-Multilayers

Hao Yang,Jiangyong Wang,Songyou Lian,Patrick Chapon,Yibing Song,Congkang Xu

doi:10.3390/coatings11060612

Abstract

Pulsed-radio frequency glow discharge optical emission spectrometry (Pulsed-RF-GDOES) has exhibited great potential for high resolution (HR) depth profiling. In this paper, the measured GDOES depth profile of 60 × Mo (3 nm)/B4C (0.3 nm)/Si (3.7 nm) was quantified by employing the newly extended Mixing-Roughness-Information depth (MRI) model. We evaluated the influences of the thickness and sputtering rate on the depth profile of very thin layers. We demonstrated that a method using the full width at half maximum (FWHM) value of the measured time-concentration profile for determining the sputtering rate and the corresponding thickness was not reliable if preferential sputtering took place upon depth profiling.

Highlights

Glow discharge optical emission spectrometry (GDOES) was initially developed for measuring the composition distribution of conductive thick films [1]
It is a great challenge for such ultrathin layers to come back to the original in-depth concentration profiles since all the distortion effects resulting from the GDOES depth profiling must be taken into account, i.e., preferential sputtering, atomic mixing from sputtering, surface/interface roughness resulting from sputtering, and/or sample nature or preparation, and the information depth from the analyzer
The extended MRI model developed for multi-element thin films was successfully applied to quantify the measured GDOES depth profiling data of 60 × Mo (3 nm)/B4 C

Summary

Introduction

Glow discharge optical emission spectrometry (GDOES) was initially developed for measuring the composition distribution of conductive thick films [1]. The quantification of a monolayer depth profile has even shown that the depth resolution of Pulsed-RF-GDOES could sometimes reach the sub-nanometer range thanks to flexibility in adjusting the pulsed radio frequency parameters [9]. It is a great challenge for such ultrathin layers to come back to the original in-depth concentration profiles since all the distortion effects resulting from the GDOES depth profiling must be taken into account, i.e., preferential sputtering, atomic mixing from sputtering, surface/interface roughness resulting from sputtering, and/or sample nature or preparation, and the information depth from the analyzer. The sputtering rate of each element and the individual layer thicknesses in the Mo/B4 C/Si multilayer are obtained

Extended MRI Model

Simulation and Discussion

Findings

Note linear relation indicates there is matrix no matrix effect upon

Conclusions