Efficient dicing of thin silicon wafers using a line focusWednesday (24.06.2020) 15:10 - 15:30 Room 2
Latest applications in semiconductor power device manufacturing showing a clear trend towards thinner Silicon thickness of far below 100µm. Reducing the thickness of the Si-bulk material is improving the performance of the chip in terms of Ron and heat dissipation, but is also adding additional requirements to the separation process. Since the stability of the chip is linked to the thickness, a gentle laser dicing is needed to handle the subsequent backend related process steps like pick-up from tape and frame and finally the packaging itself. The goal of this study is to investigate the influence of beam shaping using a line focus with different aspect ratios on the breaking strength of the die. The commercial available laser system DFL7562 from DISCO, which operate at 355nm and a pulse duration in the low ns regime, was used to optimize the dicing process in terms of cutting efficiency. Therefore different aspect ratios of the line focus were characterized and finally used to cut 12 inch bare Silicon wafers of 60µm thickness into 4mm x 2mm dies. A detailed analysis of the heat affected zone at the sidewall of the separated die using SEM and Raman spectroscopy is presented followed by three point bending test to investigate the breaking strength for the front- and backside.
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