Process exploration of β-Ga2O3 blind hole processing by water-assisted femtosecond laser technology

β-Ga2O3 is a promising high-performance material with broad application prospects in the micro-electro-mechanical-systems (MEMSs). It can be used in extreme environments such as ultralow temperatures and intense radiation, but its hardness, brittleness, and easy cleavage are the primary defect in processing. As a substrate material for the next generation of large-scale integrated circuits, blind hole processing of β-Ga2O3 has attracted intense attention. In this work, we investigated the blind hole on (010) β-Ga2O3 surfaces treated with a femtosecond-pulse laser at the wavelength of 1030 nm and the pulse width of 285 fs. Water-assisted fs laser micromachining is proposed to solve the deposition of pore debris within the hole in the air environment. Furthermore, the influence of laser pulse energy, laser pulse numbers, liquid layer thickness, and laser repetition rate on the surface morphology of the blind hole was studied by using the control variable method. The results show that precise processing of β-Ga2O3 blind holes can be achieved by controlling fs laser processing parameters. In this work, the proposed liquid-assisted fs laser machining was proved to be a reliable tool for performing high-quality β-Ga2O3 blind hole processing, which has important implications for device applications of β-Ga2O3 substrates.