AVS 50th International Symposium
    Applied Surface Science Friday Sessions
       Session AS-FrM

Invited Paper AS-FrM4
SIMS Quantification for Depth Profiling: Overview, Recent Results for Surfaces and Insulators, and Current Problems

Friday, November 7, 2003, 9:20 am, Room 324/325

Session: SIMS
Presenter: F.A. Stevie, North Carolina State University
Authors: F.A. Stevie, North Carolina State University
C. Gu, North Carolina State University
A. Pivovarov, North Carolina State University
D.P. Griffis, North Carolina State University
J.M. McKinley, NanoSpective
H. Francois-Saint-Cyr, University of Central Florida
Correspondent: Click to Email
This paper provides an overview of quantification for SIMS depth profiling and presents recent results illustrating the importance of surfaces, matrix variations, and insulators on the quantification process. Quantification is complicated by the orders of magnitude variation of secondary ion yields over the periodic table and significant variation of these ion yields for different matrices. Since practical methods for calculation of elemental sensitivity factors using theoretical methods do not exist, a standard for each element in the matrix in which it is contained is required. However, only a few standards with high accuracy have been produced. Despite these limitations, measurement precision less than 1% can be achieved. Using ion implant standards, quantification can be achieved at surfaces, within multilayered samples, at interfaces, and in bulk materials. Implantation through a removable layer provides a known quantity at a surface that can be used as a standard by many analytical techniques. Multiple layers require an understanding of each layer. A study of O2+ SIMS analysis of TaN/Ta barrier penetration by Cu shows the low secondary ion yield in the barrier compared with the SiO2 and Si regions complicates interpretation. Insulators present additional problems due to sample charging. Analysis of thin insulating films can be performed by using electrons with energy sufficient to penetrate the layer thus rendering the layer conductive. Magnetic sector SIMS analysis of GaN structures can be aided by the use of molecular secondary ions accompanied by the maximization of mass spectrometer secondary ion energy bandpass. Adequate O- primary beam density can be obtained to provide depth profiles in bulk insulators. Many aspects of quantification using SIMS still require additional study. It is difficult to extend the information from one matrix to another, and analysis of insulators such as porous low-k dielectrics present special problems.