Paper AS-TuP10
Quantitative Analysis of Si-Ge Alloy Films and Compositional Depth Profiling of Si/Ge Multi Layers Using SIMS

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

Although secondary ion mass spectrometry (SIMS) is a powerful technique for the in-depth analysis of solid materials, it is difficult to apply for the quantitative analysis of major components due to severe matrix effect. In addition, the different ionization probability caused a significance interface artefact in the interfaces between two metals due to different ionization yields.¹ However, if the variation of ionization probability is linear in a specific composition range, the interface artefact can be compensated.² A Si/Ge multilayer, Si-Ge alloy multilayer films and Si-Ge alloy films were grown on Si (100) wafers by ion beam sputter deposition. The compositions of Si-Ge alloy films were analyzed by SIMS and compared with the nominal compositions obtained by Rutherford backscattering spectroscopy. The quantification results were found to be highly improved by oxygen ions with higher energy. In SIMS depth profiles of Si/Ge multilayers using oxygen ion beam, the interfaces are difficult to be defined because of the interface artifacts in the Si/Ge and Ge/Si interfaces due to the matrix effect. However, the interfaces could be clearly defined after conversion of the profiles to composition profiles using relative sensitivity factor determined from a SIMS depth profile of a Si52.4Ge47.6 alloy film. The etching rate of a Si layer is much slower than that of Ge layer because of the formation of SiO2 layer during O2+ ion sputtering.

¹K. J. Kim and D. W. Moon, Appl. Phy. Lett., 60, 1178-1180 (1992).
²K. J. Kim, D. Simons, and G. Gillen, Appl. Surf. Sci. 253, 6000-6005 (2007).