Article

Hybrid Sputtering Approach for Reliable TOF-SIMS Depth Profiling of Inorganic-Organic Multilayer Films

Surface Analysis Spotlight: TOF-SIMS

by Jacob Schmidt     Staff Scientist

Inorganic–organic stacks are everywhere now: optics coatings, perovskite solar cells, OLEDs, fuel-cell membranes, and the failure modes live at the interfaces.

The problem: TOF-SIMS depth profiling of hybrid stacks is hard.

• Ar-GCIB is great for organics as it generates low molecular damage, preserving the molecular ions, but it sputters many inorganics painfully slowly.
• Monoatomic sputtering can remove inorganics well, but it can destroy molecular information in the organic layers.

This article shows a practical fix: co-sputtering with low-energy monoatomic cesium (Cs⁺) and an argon gas cluster beam (Ar-GCIB) to get reliable depth profiles through an inorganic overlayer without sacrificing the organic molecular information underneath.

Key takeaways:

• Low-energy Cs⁺ (0.5 keV) boosts sputter yield of the Al overlayer where Ar-GCIB struggles.
• Ar-GCIB preserves organic molecular ions, and when paired correctly, the spectra look essentially like Ar-GCIB-only conditions for the polymer sputtering.
• The example used in this paper was 40 nm Al on PC or PET films. Ar-GCIB alone couldn’t fully clear Al even after long sputtering, but the hybrid method removes Al and cleanly reaches the polymer layer.
• The authors achieved interface resolution (84–16% width of AlO⁻) of ~4.8 nm on AL/PC and ~2.0 nm on AL/PET under the optimized hybrid conditions.

This Cs⁺ / Ar-GCIB hybrid sputter approach is exactly what you want when device reliability depends on nanometer-scale chemistry at buried interfaces: high-sensitivity + depth resolution + practical sputter rates across hybrid materials without loss of molecular information.

Depth profiling results of 40 nm-thick AI films deposited on bulk PC substrates.  (a) Sputtering with Ar-GCIB alone. (b) Cosputtering using Ar-GCIB and Cs⁺ under the optimized conditions.

To learn more, you can find the original paper at J. Vac. Sci. Technol. B 43, 064006 (2025); doi: 10.1116/6.0005000