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 (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> ) 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Dlin</sub> degradation behavior has been observed during HCI stress, which is associated with two competing mechanisms, i.e., interface-state (N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">it</sub> ) 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">it</sub> and negative charges at different location of the device also support a multistage I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Dlin</sub> degradation. It is found that both initial I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> and bulk current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> ) 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.