Aluminum silicide microparticles transformed from aluminum thin films by hypoeutectic interdiffusion

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Aluminum (Al) and silicon (Si) systems are crucial in semiconductor technology.
• Controlling microparticle formation is key for advanced material applications.
• Spontaneous granulation offers a novel route for material synthesis.

Purpose of the Study:

• To investigate the formation of aluminum silicide microparticles on silicon substrates.
• To understand the underlying mechanisms of spontaneous granulation in Al-Si thin films.
• To explore the potential of these microparticles in thermoelectric applications.

Main Methods:

• Thin Al films (90 nm) were deposited on Si substrates.
• Annealing treatments were performed at 550°C for 9 hours.
• Microparticle characteristics (size, density, composition) were analyzed.
• Sheet resistance was measured to assess film changes.

Main Results:

• Aluminum silicide microparticles with oxidized rough surfaces formed via spontaneous granulation.
• Microparticle formation was driven by interdiffusion of Al and Si atoms, facilitated by compressive stress in Al films.
• Optimized conditions (550°C, 9h, 90 nm Al film) yielded high-density microparticles (~10 μm size, Si/Al ratio ~0.8).
• Microparticle formation led to a significant increase in sheet resistance due to Al consumption.

Conclusions:

• A simple, controllable method for synthesizing aluminum silicide microparticles was established.
• The process relies on annealing-induced interdiffusion and stress relaxation in Al films.
• This technique provides a foundation for thermoelectric studies on Al-Si alloy-based heterogeneous systems.