Reliability-Aware SPICE Compatible Compact Modeling of IGZO Inverters on a Flexible Substrate

Abstract

Accurate circuit simulation reflecting physical and electrical stress is of importance in indium gallium zinc oxide (IGZO)-based flexible electronics. In particular, appropriate modeling of threshold voltage (VT) changes in different bias and bending conditions is required for reliability-aware simulation in both device and circuit levels. Here, we present SPICE compatible compact modeling of IGZO transistors and inverters having an atomic layer deposition (ALD) Al2O3 gate insulator on a polyethylene terephthalate (PET) substrate. Specifically, the modeling was performed to predict the behavior of the circuit using stretched exponential function (SEF) in a bending radius of 10 mm and operating voltages ranging between 4 and 8 V. The simulation results of the IGZO circuits matched well with the measured values in various operating conditions. It is expected that the proposed method can be applied to process improvement or circuit design by predicting the direct current (DC) and alternating current (AC) responses of flexible IGZO circuits.

A Brief Review on Flexible Electronics for IoT: Solutions for Sustainability and New Perspectives for Designers

“…Since many researchers and designers in the field of electronics usually work with SPICE-like simulators, studies aimed at importing device models implemented with new materials into SPICE are of particular importance. In [248] a compact DC model of organic thin film transistors (OTFTs) and its SPICE implementation is presented and the experimental data on the fabricated devices resulted in good agreement with SPICE simulation results; in [249] a SPICE compatible compact modeling of IGZO (Indium gallium zinc oxide) transistors and inverters having an atomic layer deposition (ALD) Al2O3 gate insulator on a flexible polyethylene terephthalate (PET) substrate is proposed, that enables a reliabilityaware circuit simulation so that the operation of the flexible transistor and circuit can be predicted with high accuracy; in [250] an in-depth study of three-dimensional inkjet-printed flexible organic field-effect transistors (FETs) and integrated circuits (ICs) is reported, highlighting the necessity of modelling-driven design and analysis. With respect to such a consideration, compact modelling of the flexible printed organic FETs has been performed together with SPICE simulations of both static and dynamic behaviors of flexible printed organic circuits.…”

Threshold voltage reliability in flexible amorphous In–Ga–ZnO TFTs under simultaneous electrical and mechanical stress

“…The variation of ∆V th during PBS can be related to a competition between two mechanisms: one leading to a negative V th shift (∆V th1 ) and another leading to a positive V th shift (∆V th2 ). A double stretched exponential equation was used to reflect this situation as reported by other authors [39][40][41]:…”

Effect of Hydrogen Migration in SiO2/Al2O3 Stacked Gate Insulator of InGaZnO Thin-Film Transistors

“…The thicker the SiO2 layer is, the larger VT shift is obtained. In our previous study, the VT modulation of IGZO TFT was determined by the migration of hydrogen ions inside Al2O3 layer [35,36]. In addition, when additional SiO2 layer was deposited as a gate insulator on the Al2O3 layer, a larger VT shift was obtained under PBS because additional SiO2 deposition step helps to generate additional hydrogen by dissociating the Al-H bonds in Al2O3 layer.…”