Laser-micromachining for 3D silicon detectors

We laser-micromachined hole arrays into silicon with aspect ratios up to 100:1. Direct laser-drilling and trepanning were used. Since laser-machining leaves a damaged silicon region that is not suitable for detector fabrication, we removed the damaged silicon with an isotropic xenon difluoride etch step. Hole arrays with trepan drilled holes had lower leakage currents. We successfully collected a Co-57 photon spectrum (energy resolution: 3.0 keV FWHM at 122 KeV) with a 3D silicon detector based on trepan-drilled holes. Our results show that silicon laser-machining can be used for 3D detector fabrication with good charge collection properties.