Slicing crystalline silicon wafer by deep subsurface laser processing and selective chemical etching

Abstract

In this work, we demonstrate use of laser-induced silicon slicing (LASIS) technique to fabricate crystalline silicon (c-Si) slices [1]. In LASIS method, a nanosecond-pulsed fiber laser operating at 1.55 μm wavelength, focused deep in Si subsurface induces structural modifications near the focal point due to multiphoton absorption. The raster scan of the focal position inside of the sample, positioned in cross-sectional plane with respect to laser beam, produces a quasi-2D modified Si region. The modified Si region is then etched by cupper nitrite (Cu(NO 3 ) 2 )-based selective chemical etchant which selectively targets the laser-modified regions. In order to achieve high etch rate, smooth and defect-free surface; different concentrations of etchant components and etch durations were investigated.