Investigation of Endurance Degradation Mechanism of Si FeFET With HfZrO Ferroelectric by an In Situ Vth Measurement

We propose an in situ
${V}_{\text {th}}$
measurement method to investigate the endurance fatigue mechanism of Si ferroelectric field-effect transistor (FeFET) with HfZrO ferroelectric. The in situ
${V}_{\text {th}}$
measurement method means that a pulsed current-voltage measurement is embedded during the quasi-static capacitance-voltage (QSCV) measurement. Based on this method, the trapped charges can be extracted as a function of the gate voltage (
${V}_{g}{)}$
. We find that: First, the trapped electrons and holes show asymmetric de-trapping dynamics. Excess electrons continuously de-trap within the
${V}_{g}$
ranging from the maximum positive value to ferroelectric reverse switching. However, the trapped holes do not de-trap when the
${V}_{g}$
changes from the minimum negative value to 0 V. Second, the increase of donor trap density is the key to endurance fatigue. During endurance fatigue, the total amounts of trapped electrons are unchanged near the maximum positive voltage, but the amounts of de-trapped electrons decrease when the
${V}_{g}$
returns to 0 V due to donor trap density increases. In addition, we apply our method in the scaled FeFET to overcome the measurement limitation of gate charges (
${Q}_{m}{)}$
by the nowadays equipment.