New Power MOSFET Employing Segmented Trench Body Contact for Improving the Avalanche Energy

We have fabricated the 60 V power MOSFET employing the segmented trench body contact which results in low conduction loss and high avalanche energy (EAS) under undamped inductive switching (UIS) condition without sacrificing the device area. The proposed device employs the CMOS compatible deep Si trench process. The segmented trench body contact suppresses the hole current beneath the n+ source region under the avalanche breakdown mode because the impact ionization begins at the bottom of the trench contact, which suppresses the activation of parasitic NPN bipolar transistor and improves the EAS. We have investigated the avalanche characteristics by testing devices under UIS. The measured EAS of the proposed device is 4.5 mJ while that of the conventional one is 1.84 mJ. Although the breakdown voltage decreased from 69.8 V to 60.4 V by 13% due to the trench body contact, E_AS improved by 144%. Trench segmentation increases the n+ source contact area which results in reducing the on- resistance and improving the uniformity of the trench body contact and active cells.