Extraction of structure parameters of a-IGZO TFTs based on CV measurement

Capacitance-voltage (CV) characteristics of amorphous In-Ga-Zn-O (a-IGZO) thin film transistors (TFTs) with different layouts in the gate area, active area, etch-stop layer and contact windows are investigated. The layout dependence of the capacitance values under the channel depletion and accumulation are clarified. Based on the dependencies, capacitance differences between TFTs with different layouts under the channel depletion or accumulation can be exploited to extract capacitances for all structure layers, from which thicknesses of different layers can be calculated solely based on CV measurement. CV extracted values agree well with the technology values, demonstrating the feasibility of the proposed method.