Optimizing Collector-Emitter Saturation Voltage at 3000 V Insulated Gate Bipolar Transistors Using Laser Thermal Annealing
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In this work, two thermal annealing processes (furnace and laser annealing) are adopted to obtain < 2.0 V collector-emitter saturation voltage (Vce(sat)), an important device parameter giving an effect on switching speed and power consumption of > 3000 V breakdown voltage in insulated gate bipolar transistors (IGBTs) for propulsion control system of electric vehicles. In furnace annealing process (450 °C for 30 min), the parameter of Vce(sat) is 5.5–6.5 V once measuring at Ic = 2.0 A with EDS(electrical die sorting) analyser. However, annealing process was performed using a laser equipment to lower the Vce(sat). After back side grinding and back side implant, the sample wafer undergoes laser annealing process. From various annealing conditions it was found that the Vce(sat) was 1.6–1.7 V when measuring at collector current (Ic) of 2.0 A after annealing at pulse with of 1100 nm, 3-overlap and 3.5 J/cm2. From these results, it is found that the Vce(sat) is lower as increasing laser energy density and overlapping and the well-distributed Vce(sat) values over the entire chips appear as widening the laser pulse.
KeywordsInsulated gate bipolar transistors Furnace annealing Laser annealing Electrical die sorting Collector-emitter saturation voltage
This research was supported by a Grant (Code 13RTRP-B067917-01) from Railroad technology research Program funded by Ministry of Land, Infrastructure and Transport of Korean government.
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