Simulation and experimental Demonstration on A retrograde drift LDMOS

In this article, an RD (Retrograde drift) LDMOS (Lateral double diffused metal oxide semiconductor) device is introduced. The drift region in this proposed device is trapezoidal in shape and gradually decreases from top to bottom in doping concentration, called “retrograde drift.” Simulations indicate that this RD device has an 11.7% lower electric field peak value, 6.2% lower potential under the poly gate, 32.1% higher current width in the drift region, and 10.5% lower impact gen rate at the corner of FP (Field plate) as well. A series of devices have been fabricated using a photoresist treatment process. Compared with the conventional BD (box-shape drift) device, the RD device’s $\mathrm{BV}$(Breakdown voltage)-$R_{\mathrm{on},sp}$ (on-resistance) FOM (Figure of merit) performance is improved by 30.9%, and the $Q_{\mathrm{gd}}$(Gate-drain charge)-$R_{\mathrm{on},sp}$ FOM character is improved by 42.1%. Moreover, the RD device owns better HCI (Hot carrier injection) performance on both $R_{\mathrm{on},sp}$ degradation and $V_T$ (Threshold voltage) degradation.