Studies on Quantification Analysis of Thin Film Layers (Si₃N₄, SiO₂, and TiW) in Wafer Fabrication Using Energy-Dispersive X-Ray Microanalysis Technique and SEC Factors

Abstract

Currently standardless EDAX ZAF quantification method has been widely used in many new generation FESEM machines. This method is able to provide good and reliable elemental results for bulk samples and some films for some particles and contamination analysis, but for some cases, EDX results may not be accurate, especially for thin film layer identification in wafer fabrication. In this paper, standardless EDAX ZAF quantification method will be further studied and an EDX quantification analysis method with the SEC factor correction will be introduced. The SEC factors can be calculated using current EDAX software. Application results from passivation thin film Si₃N₄, SiO₂ layers and barrier metal thin film TiW layer show that the EDX results have been greatly improved after performing the SEC factor correction and the relative error is greatly reduced from 64.3–101% to 0.23–3.93% for passivation Si₃N₄ layer, from 51.5–62.3% to 0.73–3.10% for passivation SiO₂ layer and from 18.2–77.0% to 0.04–11.5% for barrier metal TiW layer. If we assume that the passivation and barrier metal layers always have a stoichiometric composition, this method could be used for the monitoring purpose in wafer fabrication.

Keywords:

• Energy-dispersive X-ray microanalysis
• Standardless EDAX ZAF quantification method
• SEC factor correction
• Wafer fabrication
• Thin film layers (passivation Si₃N₄ and SiO₂ and barrier metal TiW)

Acknowledgments

The author would like to thank Miss Ang Suet-Whee (National University of Singapore) and Mr. Y. M. Tay (Nanyang Technological University, Singapore) for their assistance and contributions to this project.