Investigation of multistage linear region drain current degradation and gate-oxide breakdown under hot-carrier stress in BCD HV PMOS

Hot-carrier injection (HCI) at maximum gate current (I
_G
) stress condition for BCD HVPMOS has been studied. It is found that HCI not only causes linear region drain current degradation and minimizes the operation window, but also degrades the gate oxide (GOX) and may result in GOX breakdown. A multistage I
_Dlin
degradation behavior has been observed during HCI stress, which is associated with two competing mechanisms, i.e., interface-state (N
_it
) generation and electron trapping caused by hot electrons originated from impact ionization. HCI leads to the gate oxide breakdown even at very low e-field of ~1.5MV/cm across the GOX. TCAD simulation results by placing N
_it
and negative charges at different location of the device also support a multistage I
_Dlin
degradation. It is found that both initial I
_G
and bulk current (I
_B
) are well correlated with GOX time-dependent-dielectric-breakdown (TDDB). In addition, better TDDB has been observed at higher temperature compared to lower temperature, which verifies that GOX breakdown is associated with HCI.