Laser Assisted SiC Wafering Using COLD SPLIT

Abstract

Kerf-free wafering techniques hold the potential to drastically reduce material losses in semiconductor manufacturing processes. Spalling processes use externally applied stresses to separate crystalline materials along crystal planes with well-defined thickness. Spalled substrates, however, exhibit striations from crack propagation along the crystal, a pattern called Wallner lines. Here, we demonstrate a wafering process that scales favorably for SiC substrates starting from 1 inch in diameter. To eliminate the Wallner line pattern, we use a laser-conditioning process with high numerical aperture at photon energies below the material bandgap energy, using multi-photon effects. The process leads to SiC surfaces with a roughness after spalling of Ra< 4μm.