Argon cluster ion beams for organic depth profiling: results from a VAMAS interlaboratory study

Area of Science:

• Surface science
• Materials analysis
• Analytical chemistry

Background:

• Depth profiling of organic materials is crucial for understanding surface properties.
• Argon cluster ion sputtering is a new technique for this analysis.
• Previous studies focused on C(60)(+) cluster sources.

Purpose of the Study:

• To assess the performance of argon cluster ion sputtering for organic material depth profiling.
• To compare argon cluster sputtering with C(60)(+) cluster sputtering.
• To evaluate sputtering yields and depth resolution in an interlaboratory study.

Main Methods:

• Interlaboratory study involving four laboratories using time-of-flight secondary-ion mass spectrometry.
• Analysis of organic multilayer reference materials (Irganox 1010 matrix with Irganox 3114 marker layers).
• Sputtering using 2.5 and 5 keV argon cluster ions and C(60)(+) cluster ions.

Main Results:

• Argon cluster sputtering demonstrated effectively constant sputtering yields through the reference materials.
• Depth resolutions approaching 5 nm (fwhm) were achieved using molecular secondary ions.
• Sputtering yields and depth resolutions were comparable to C(60)(+) cluster sputtering data.
• Negligible variation in sputtering yield with depth and high repeatability (better than 1%) were observed with argon clusters.
• Marker layer position shifts up to 3 nm were noted with argon cluster sputtering, dependent on the secondary ion used.
• Electron irradiation for charge compensation induced significant molecular damage.

Conclusions:

• Argon cluster sputtering is a viable and effective technique for organic material depth profiling.
• It offers advantages in terms of sputtering yield stability and repeatability compared to previous methods.
• Careful selection of secondary ions and consideration of electron irradiation effects are necessary for accurate depth profiling.