The Research Of Hot Carrier Injection Reliability On Deep Submicron N-type High-voltage DDDMOSFET

To reduce circuit complexity and chip size, high-voltage Double Diffused Drain MOSFET (HV DDDMOSFET) transistor is integrated with submicron CMOS integrated circuit in LCD drivers, power management IC and many application specific standard products. DDDMOSFET transistor is more attractive to circuit designers due to DDDMOSFET process completely compatible CMOS process, a symmetric drain/source structure, and a smaller device pitch. But high-voltage device is operated under high Vds and Vgs, it form high lateral electric field and vertical electric field in device as smaller and smaller device pitch, which will induce hot-carrier injection more serious.So,hot-carrier injection reliability may become a serious challenge in HV DDDMOSFET.Besed on discussing low voltage MOSFET hot carrier injection mechanism and test methods, this thesis intevetage N-type High-voltage DDDMOSFET hot carrier injection behaviors. The results show that the high-voltage double-diffused drain MOSFET's substrate current increased again to reach a peak at Vg=Vd after substrate current arrive the first peak near Vg= Vd/A, which is different from low voltage MOSFET with only a substrate current peak. Hot carrier injection is very serious both N-type high-voltage double-diffused drain MOSFET stressed under the first substrate current peaks bias and the other one. And the hot carrier injection induce device performance degradation cause by not only hot electron injection, but also hot hole injection.Based on 0.25μm CMOS technology 15V N-type DDDMOSFET, the DDDMOSFET's gate oxide and its unique Offset areas were optimized to improve its hot carrier injection reliability in this thesis. The results show that the gate oxide high-temperature annealing can improve the DDDMOSFET hot carrier injection but little; increase the Offset area drive-in temperature, reduce the Offset area ion implantation dose and the Offset area drive-in with O2 can improve DDDMOSFET hot carrier injection reliability greater,and hot carrier injection lifetime extend to twice, four times and eight times respectively. By reduce the Offset area ion implantation dose and drive-in with O2 together, DDDMOSFET hot carrier injection lifetime will be extend to twenty times,which suggest that the optimization improving the DDDMOSFET hot carrier injection reliability greatly. The conclusions of this thesis provide a possible way to significantly improve the hot-carrier injection reliability of N-type DDDMOSFET by way of optimizing process, while maintain the electric characteristics and change the process condition very little.