Change in the microstructure at W/Si interface and surface by swift heavy ions

Area of Science:

• Materials Science
• Surface Science
• Ion Beam Modification

Background:

• Metal/semiconductor interfaces are crucial in microelectronics.
• Swift heavy ion (SHI) irradiation offers controlled modification of material interfaces.
• Understanding ion-induced atomic mixing is key for novel material development.

Purpose of the Study:

• To investigate the atomic mixing and structural evolution at W/Si interfaces under SHI irradiation.
• To characterize the formation of tungsten silicides and analyze the surface morphology changes.
• To elucidate the underlying mechanism of ion-induced atomic mixing at the W/Si interface.

Main Methods:

• Irradiation of W/Si thin films using 120 MeV Au(+9) ions.
• Structural analysis using Grazing Incident X-ray Diffraction (GIXID).
• Compositional depth profiling via Rutherford Backscattering Spectroscopy (RBS).
• Surface morphology investigation using Atomic Force Microscopy (AFM).

Main Results:

• Formation of two tungsten silicides, t-W(5)Si(3) and t-WSi(2), at the W/Si interface.
• Evidence of atomic mixing and transient molten phase formation, consistent with the Thermal Spike Model.
• Increased surface roughness and grain size with increasing ion fluence, indicating surface modification.

Conclusions:

• SHI irradiation provides a controlled method for modifying W/Si interfaces and inducing silicide formation.
• The observed atomic mixing is attributed to a transient molten phase mechanism.
• Surface topography is significantly altered by ion irradiation, with roughness and grain size increasing with fluence.