Overview

The XPS depth profile illustrated below analyzes a 22-layer dielectric reflective film made of SiO₂ and tantalum oxide (Ta₂O₅) on the interior wall of a hollow quartz material. Depth profiles reveal the elemental composition as a function of depth, providing insights into the structure and characteristics of multi-layer films.

Analysis Process

We used a rastered, differentially pumped argon ion gun at 4 keV to sputter the surface of the reflective dielectric film. The sputter rate of SiO₂ allowed us to measure the thickness of each layer within the dielectric film.

Findings

The XPS depth profile shows alternating layers of SiO₂ and non-stoichiometric TaOₓ, with SiO₂ being the first layer. The outer layers of the film are thinner compared to the inner layers. Notably, the initial SiO₂ protective layer is thicker than the subsequent outer SiO₂ layers.

However, an anomaly occurred in the 8th layer of the profile, which should have been a TaOₓ layer. Instead, it appears as a mixed layer. We observed a local maximum of tantalum (Ta) that was lower than the silicon (Si) concentration at that depth. Additionally, the oxygen concentration in the TaOₓ layer was less than expected, showing a 25% deficit compared to the SiO₂ layer. Conversely, the carbon concentration in the TaOₓ layers was higher than in the SiO₂ layers, particularly in the deeper layers, though it fluctuated from layer to layer.

Cause of Variations

The variations in Ta and carbon concentrations were due to a malfunctioning valve system in the deposition chamber of our customer’s subcontractor.

Conclusion

The XPS depth profile highlights the alternating structure of the dielectric film and reveals issues with layer composition due to equipment malfunctions. Understanding these variations helps in refining the deposition process and improving film quality.

Additional Information

For more details on XPS depth profiles, visit our XPS page.

Contact Us

For further assistance with XPS depth profiling or other material analysis needs, please contact us today. Our team of experts is ready to provide accurate analysis and solutions tailored to your specific requirements.