An Investigation on Anomalous Hot-Carrier-Induced On-Resistance Reduction in n-Type LDMOS Transistors

In this paper, on-resistance (
R

_on
) degradation induced by hot-carrier injection in n-type lateral diffused metal-oxide-semiconductor transistors with shallow trench isolation (STI) in the drift region is investigated.
R

_on
unexpectedly decreases under medium- and high-gate voltage (
V

_gs
) stress conditions. According to experimental data and technology computer-aided-design simulation results, the mechanisms responsible for anomalous
R

_on
shift are proposed. When the device is stressed under medium
V

_gs
, hot-hole injection and trapping occur at the STI edge closest to the channel, resulting in
R

_on
reduction. Interface trap generation (¿
N

_it
) occurs at the STI edge closest to the channel and nearby drift region, leading to
R

_on
increase. For the device stressed under high
V

_gs
,
R

_on
reduction is also attributed to hole trapping at the STI corner closest to the channel. ¿
N

_it
created by hot-electron injection at the STI edge closest to the drain dominates device characteristics and leads to
R

_on
increase eventually. Based on the proposed
R

_on
degradation mechanisms, an
R

_on
degradation model is discussed and verified with experimental data.