The TDDB Characteristics of Ultra-Thin Gate Oxide MOS Capacitors under Constant Voltage Stress and Substrate Hot-Carrier Injection

Abstract

The breakdown characteristics of ultra-thin gate oxide MOS capacitors fabricated in 65 nm CMOS technology under constant voltage stress and substrate hot-carrier injection are investigated. Compared to normal thick gate oxide, the degradation mechanism of time-dependent dielectric breakdown (TDDB) of ultra-thin gate oxide is found to be different. It is found that the gate current ( ) of ultra-thin gate oxide MOS capacitor is more likely to be induced not only by Fowler-Nordheim (F-N) tunneling electrons, but also by electrons surmounting barrier and penetrating electrons in the condition of constant voltage stress. Moreover it is shown that the time to breakdown ( bd ) under substrate hot-carrier injection is far less than that under constant voltage stress when the failure criterion is defined as a hard breakdown according to the experimental results. The TDDB mechanism of ultra-thin gate oxide will be detailed. The differences in TDDB characteristics of MOS capacitors induced by constant voltage stress and substrate hot-carrier injection will be also discussed.

Experimental Study on Critical Parameters Degradation of Nano PDSOI MOSFET under TDDB Stress

“…The I-V characteristics, threshold voltage, and transconductance remain the same before and after the soft breakdown in the Core device. In JY Shen’s study of 2 nm and 5.6 nm thick-gate oxide NMOS capacitors, there are several soft breakdown events in the 2 nm ultra-thin-gate oxide [ 14 ]. When the soft breakdown occurs, the gate current jumps up.…”

“…The MOSFET I-V characteristic curves, threshold voltage, and transconductance will be shifted during the TDDB stress. When the TDDB effect is combined with additional reliability effects such as the radiation effect and HCI (hot carrier induce) effect, the changes in device characteristics will be further complicated [ 11 , 12 , 13 , 14 ]. In recent research, different TDDB mechanisms were discovered in modern-generation semiconductor devices [ 15 , 16 ].…”