[paper] Effect of the AC-Signal Frequency on Flat-Band Voltage of Al/HfO2/SiO2/Si Structures

Andrzej Mazurak, Bogdan Majkusiak

Investigation of the Anomalous Effect of the AC-Signal Frequency 

on Flat-Band Voltage of Al/HfO2/SiO2/Si Structures

Solid-State Electronics (2021) SSE 108107 

DOI:10.1016/j.sse.2021.108107

*TU Warsaw, Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw, Poland

Abstract: MIS structures with double-layer HfO2/SiO2 gate stacks were fabricated. The admittance measurements revealed an anomalous voltage shift of the capacitance-voltage characteristics, modulated by the ac signal frequency. The effect is discussed in terms of the oxide charge modulation through the frequency dependent leakage mechanism.

Fig: Measured Gpm conductance–voltage characteristics for the n-type MIS structure.

• An anomalous effect of the ac-signal frequency on the voltage shift of the CV characteristics of Al/HfO2/SiO2/Si devices was observed.
• The observed effect is stable, reproducible, and reversible and is not driven by the measurement procedure or the measurement protocol parameters.
• The effect is explained through a frequency dependent leakage conductance which affects the electric charge trapped interior the gate stack.
• A linear dependence of the leakage conductance on the ac signal frequency is observed.