High aspect ratio diamond nanosecond laser machining.

Area of Science:

• Materials Science
• Laser Physics
• Quantum Technology

Background:

• Laser processing is crucial for fabricating advanced microelectronic and quantum devices using diamond.
• Achieving high aspect ratio and low taper structures in diamond via laser machining presents significant challenges.

Purpose of the Study:

• To investigate the effects of laser pulse energy, number, and irradiation profile on diamond structure aspect ratio.
• To explore methods for fabricating low taper, high aspect ratio diamond structures.
• To analyze laser-induced damage and the efficacy of thermal annealing for strain reduction.

Main Methods:

• Utilized 532 nm nanosecond laser machining with percussion and rotary assisted drilling techniques.
• Investigated various pulse energies, pulse numbers (up to 2M), and irradiation profiles.
• Employed confocal Raman spectroscopy to study laser-induced strain and heat treatment effects.

Main Results:

• Achieved aspect ratios of 22:1 with percussion drilling and >40:1 (up to 66:1) with rotary assisted drilling.
• Demonstrated 0.1° taper angles using ramped pulse energy machining.
• Observed up to 36% tensile strain increase post-irradiation, reduced by ~50% with 600°C heat treatment.

Conclusions:

• Rotary assisted laser drilling is effective for achieving high aspect ratio diamond structures.
• Laser machining parameters critically influence achievable aspect ratios and taper angles.
• Thermal treatment can mitigate laser-induced strain in diamond, crucial for device stability.