Hybrid slicing of laser-modified 4H-SiC chips using a Langevin transducer, with modeling informed by micro-fracture tests

A novel hybrid slicing process combining laser modification and mechanical vibration enables highly efficient slicing of ultrahard 4H-SiC chips with low kerf loss. A picosecond pulsed laser was used to thermally-induce discontinuous [ 11 2 ̅ 0 ] micro-cracks within the SiC chip, and a Langevin transducer was used to induce vibrational stresses to grow the micro-cracks until full chip separation. Finite-element modeling (FEM) informed by site-specific micro-cantilever fracture tests were used to calculate the voltage and stresses required for separating the chips. By applying a voltage of 32.5 V to the Langevin transducer, a tensile stress of 5.29 MPa can be generated for separating the chips immediately. Lowering the applied voltage resulted in a fatigue-like separation process. SEM analysis of the separated 4H-SiC chips revealed a jagged fracture surface, indicating crack extended along both [ 11 2 ̅ 0 ] and [0001] direction, which was nicely captured by the FEM. Overall, this hybrid chip slicing process provides an attractive alternative by eliminating the need for expensive cutting consumables (diamond blade, wire), significantly improves slicing efficiency (2 sec/piece), and greatly reduces the kerf loss (surface cracking) when comparing to conventional machining processes. • Vibration-induced separation occurs in milliseconds for 1 cm 2 4H-SiC chip slicing. • FEM and micro-fracture tests reveal crack paths and key stress/voltage for chip slicing. • Langevin piezoelectric transducer provides sufficient vibration energy for propagating cracks. • Lower transducer voltage enables fatigue-like cracks to reduce the risk of chip breaking.