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

Abstract

Hot-carrier injection (HCI) at maximum gate current (IG) 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 IDlin degradation behavior has been observed during HCI stress, which is associated with two competing mechanisms, i.e., interface-state (Nit) 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 Nit and negative charges at different location of the device also support a multistage IDlin degradation. It is found that both initial IG and bulk current (IB) 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.