Dual Laser Beam Asynchronous Dicing of 4H-SiC Wafer

Abstract

SiC wafers, due to their hardness and brittleness, suffer from a low feed rate and a high failure rate during the dicing process. In this study, a novel dual laser beam asynchronous dicing method (DBAD) is proposed to improve the cutting quality of SiC wafers, where a pulsed laser is firstly used to introduce several layers of micro-cracks inside the wafer, along the designed dicing line, then a continuous wave (CW) laser is used to generate thermal stress around cracks, and, finally, the wafer is separated. A finite-element (FE) model was applied to analyze the behavior of CW laser heating and the evolution of the thermal stress field. Through experiments, SiC samples, with a thickness of 200 μm, were cut and analyzed, and the effect of the changing of continuous laser power on the DBAD system was also studied. According to the simulation and experiment results, the effectiveness of the DBAD method is certified. There is no more edge breakage because of the absence of the mechanical breaking process compared with traditional stealth dicing. The novel method can be adapted to the cutting of hard-brittle materials. Specifically for materials thinner than 200 μm, the breaking process in the traditional SiC dicing process can be omitted. It is indicated that the dual laser beam asynchronous dicing method has a great engineering potential for future SiC wafer dicing applications.

Slicing of 4H‐SiC Wafers Combining Ultrafast Laser Irradiation and Bandgap‐Selective Photo‐Electrochemical Exfoliation

“…A thin damage layer is thus created inside the semiconductor single crystal by the ultrafast laser writing throughout the surface of the semiconductor. [14][15][16] The slicing of semiconductor wafers can be realized by exfoliating the damage layer from the perfect single-crystal region via mechanical stress, swelling stress, or thermal stress. [9,17,18] By replacing wire sawing with ultrafast laser slicing, the material loss and slicing duration per wafer are significantly reduced.…”

Precision Layered Stealth Dicing of SiC Wafers by Ultrafast Lasers

“…Amit Yadav et al [ 21 ] have investigated the SD of sapphire wafers with near-infrared femtosecond pulses to leave a high-quality surface, and Caterina Gaudiuso et al [ 22 ] applied a femtosecond laser to SD on quartz glass. Zhang et al [ 23 ] proposed a new asynchronous double-beam laser SD method, in which an ultrafast laser is focused inside of the SiC wafer along the writing line to form microcracks, heated by continuous lasering to expand the cracks through thermal stress, achieving the dicing of a 200 μm SiC wafer with almost no damage to the kerf. However, it is only suitable for thicknesses less than 200 µm.…”

Investigation on the Processing Quality of Nanosecond Laser Stealth Dicing for 4H-SiC Wafer

“…Caterina G. et al 23 reported a one-step method cutting the quartz with femtosecond laser SD, and studied the influence of relevant parameter on processing. Zhang et al 24 reported an asynchronous double-beam laser SD method, which includes SD process with pulse laser and split process with continuous laser. Nevertheless, cost and stability are the issue that have to be considered in industrial manufacture yet.…”