Laser-assisted spalling of large-area semiconductor and solid state substrates

Using kerf-free wafering technologies material losses in semiconductor manufacturing processes can be reduced drastically. By the use of externally applied stress, crystalline materials can be separated along crystal planes with clearly defined thickness. Nevertheless, during this process striations caused by the crack propagation occur. These crack growth features are river and Wallner lines. In this work, we demonstrate a process for spalling that scales favorably for large-area semiconductor substrates with a diameter up to 300 mm. To get rid of the crack growth features, a laser-conditioning process with a high numerical aperture at photon energies below the material bandgap energy, using multi-photon effects is utilized. The process affords a surface roughness R a after spalling of <1 µm.