High-Quality Micromachining of Silicon at 1064 nm Using a High-Brightness MOPA-Based 20-W Yb Fiber Laser

The advances in design, performance, cost reduction, and brightness for the modern Yb fiber lasers have opened up the possibility of redefining the processing options of semiconductor materials at a wavelength of 1064 nm. The usual laser of choice for Si processing is the 355- or 266-nm diode-pumped solid-state system. The provision of a new master oscillator power amplifier (MOPA)-based high-brightness Yb-based fiber laser configuration has provided a range of pulse parameters (30-50 ns full-width at half-maximum), peak powers approaching ~2 GWmiddotcm^-2, and pulse repetition rates up to 500 kHz. These processing parameters offer a broad range of material response characteristics. This paper provides a preliminary analysis of the response of Si to the new MOPA-based Yb laser operating at maximum average power of 20 W. Results presented here show no signs of the usual thermally induced deleterious effects (microcracking, heavy recast layers, and surface damage) normally associated with Si interactions at 1064 nm. Volumetric etch rates of up to 230 000 000 mum³middots^-1 were observed with a high-quality percussion drilling interaction at a repetition rate of 25 kHz and an average power of 20 W.