Persistent Sputtering Yield Reduction in Plasma-Infused Foams

Area of Science:

• Materials Science
• Plasma Physics
• Surface Engineering

Background:

• Sputtering yield is crucial for plasma-based material processing.
• Microstructured surfaces like foams can alter plasma-surface interactions.
• Understanding sputtering behavior in complex geometries is essential for optimizing thin film deposition and etching.

Purpose of the Study:

• To quantify the sputtering yield reduction of aluminum microfoams under argon plasma bombardment.
• To develop an analytical model explaining the influence of foam geometry and plasma sheath on sputtering.
• To differentiate sputtering regimes based on plasma infusion into the foam structure.

Main Methods:

• Experimental measurement of sputtering yields for aluminum microfoams and flat aluminum surfaces.
• Bombardment with 100 to 300 eV argon plasma.
• Development and application of an analytical model considering foam geometry and plasma sheath thickness.

Main Results:

• Aluminum microfoams exhibited 40%-80% lower sputtering yields than flat surfaces.
• Sputtering yield strongly depends on foam geometry and plasma sheath characteristics.
• Plasma infusion into pores larger than the sheath thickness leads to volumetric sputtering phenomena and significant yield reduction via geometric recapture.

Conclusions:

• Microfoam geometry and plasma infusion fundamentally alter sputtering dynamics.
• Geometric recapture of sputtered particles is a key mechanism for yield reduction in plasma-infused foams.
• Lower ion energies enhance sputtering yield reduction in foams due to more effective particle recapture.