HfO2/Hf/Si MOS 구조에서 나타나는 HfO2박막의 물성 및 전기적 특성

Abstract

In this paper, Thin films of <TEX>$HfO_2$</TEX>/Hf were deposited on p-type wafer by Atomic Layer Deposition (ALD). We studied the electrical and material characteristics of <TEX>$HfO_2$</TEX>/Hf/Si MOS capacitor depending on thickness of Hf metal layer. <TEX>$HfO_2$</TEX> films were deposited using TEMAH and <TEX>$O_3$</TEX> at <TEX>$350^{\circ}C$</TEX>. Samples were then annealed using furnace heating to <TEX>$500^{\circ}C$</TEX>. Round-type MOS capacitors have been fabricated on Si substrates with <TEX>$2000\;{\AA}$</TEX>-thick Pt top electrodes. The composition rate of the dielectric material was analyzed using TEM (Transmission Electron Microscopy), XRD (X-ray Diffraction) and XPS (X-ray Photoelectron Spectroscopy). Also the capacitance-voltage (C-V), conductance-voltage (G-V), and current-voltage (I-V) characteristics were measured. We calculated the density of oxide trap charges and interface trap charges in our MOS device. At the interface between <TEX>$HfO_2$</TEX> and Si, both Hf-Si and Hf-Si-O bonds were observed, instead of Si-O bond. The sandwiched Hf metal layer suppressed the growing of <TEX>$SiO_x$</TEX> layer so that <TEX>$HfSi_xO_y$</TEX> layer was achieved. And finally, the generation of both oxide trap charge and interface trap charge in <TEX>$HfO_2$</TEX> film was reduced effectively by using Hf metal layer.