High-quality high-throughput silicon laser milling using a 1 kW sub-picosecond laser

Area of Science:

• Materials Science
• Laser Machining
• Nanotechnology

Background:

• Laser milling is a key technique for precise material processing.
• High-power lasers offer potential for increased throughput in silicon micromachining.
• Managing thermal effects is crucial for achieving high-quality results in laser-based material removal.

Purpose of the Study:

• To demonstrate high-quality, high-throughput laser milling of silicon using a high-power, sub-picosecond laser.
• To investigate processing strategies that mitigate heat accumulation effects.
• To achieve smooth surface finishes and high material removal rates.

Main Methods:

• Utilized a sub-picosecond laser with >1 kW average power.
• Employed a processing strategy with five-pulse bursts and a large beam diameter (372 µm).
• Operated at a high feed rate of 24 m/s to limit peak fluence (~0.7 J/cm²).

Main Results:

• Achieved smooth silicon surfaces with roughness Sa ≤ 0.6 µm.
• Successfully milled to a depth of 313 µm.
• Maintained a high material removal rate of 230 mm³/min.

Conclusions:

• High-power, short-pulse laser milling enables efficient and high-quality processing of silicon.
• Optimized burst mode and beam parameters are effective in controlling thermal effects.
• The demonstrated method is suitable for high-throughput fabrication of microstructures in silicon.