A New Mechanism of Symmetry of Current-Voltage Characteristics for High-k Dielectric Capacitor Structures

Abstract

Historically, there has been a controversy regarding whether the leakage current versus voltage (I-V) relationship is governed by the Schottky mechanism or by the Poole-Frenkel (P-F) mechanism for several decades. For the P-F mechanism, the I-V characteristics is expected to be symmetrical. In this paper, the author points out that there is an extra mechanism for symmetrical I-V characteristics.

An Extended Unified Schottky-Poole-Frenkel Theory to Explain the Current-Voltage Characteristics of Thin Film Metal-Insulator-Metal Capacitors with Examples for Various High-k Dielectric Materials

“…For example, this was discussed by Lau in 2012. 24 For a semiconductor p-n junction, the forward characteristics can be represented by a small forward voltage V F such that the current through the p-n junction is very large when the bias voltage is above V F while the current is zero when the bias voltage is below V F . For a silicon p-n junction, V F is about 0.7 V. Similarly, for a metal/semiconductor Schottky barrier, the forward I-V characteristics can be characterized by a small forward voltage V F ; V F is usually smaller for a Schottky diode compared to a p-n junction diode.…”

“…The author believes that the results from Yamaguchi et al and Aleskandrova et al can be understood if an assumption is made that their ZrO 2 /SiO 2 /Si interfacial region had a very large quantity of defect states. According to Lau 2012, 24 a very large quantity of defect states, which may originate from the interaction between ZrO 2 and Si during ZrO 2 deposition and subsequent processing, make the effective Schottky barrier height lower and also insensitive to the choice of metal (for this case, n + -Si or p + -Si). It can be imagined that the Al gate was deposited at near room temperature and the interaction between Al and ZrO 2 at low processing temperature is not as strong as that between ZrO 2 and Si at high processing temperature and the effective Schottky barrier height at the Al/ZrO 2 interface is higher than that at the ZrO 2 /SiO 2 /Si interfacial region.…”