Comparison of Hafnium Dioxide and Zirconium Dioxide Grown by Plasma-Enhanced Atomic Layer Deposition for the Application of Electronic Materials

Abstract

We report the growth of nanoscale hafnium dioxide (HfO2) and zirconium dioxide (ZrO2) thin films using remote plasma-enhanced atomic layer deposition (PE-ALD), and the fabrication of complementary metal-oxide semiconductor (CMOS) integrated circuits using the HfO2 and ZrO2 thin films as the gate oxide. Tetrakis (dimethylamino) hafnium (Hf[N(CH3)2]4) and tetrakis (dimethylamino) zirconium (IV) (Zr[N(CH3)2]4) were used as the precursors, while O2 gas was used as the reactive gas. The PE-ALD-grown HfO2 and ZrO2 thin films were analyzed using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). The XPS measurements show that the ZrO2 film has the atomic concentrations of 34% Zr, 2% C, and 64% O while the HfO2 film has the atomic concentrations of 29% Hf, 11% C, and 60% O. The HRTEM and XRD measurements show both HfO2 and ZrO2 films have polycrystalline structures. n-channel and p-channel metal-oxide semiconductor field-effect transistors (nFETs and pFETs), CMOS inverters, and CMOS ring oscillators were fabricated to test the quality of the HfO2 and ZrO2 thin films as the gate oxide. Current-voltage (IV) curves, transfer characteristics, and oscillation waveforms were measured from the fabricated transistors, inverters, and oscillators, respectively. The experimental results measured from the HfO2 and ZrO2 thin films were compared.

Structural, Optical and Electrical Properties of HfO2 Thin Films Deposited at Low-Temperature Using Plasma-Enhanced Atomic Layer Deposition

“…However, HfO 2 thin films normally must be deposited at around 200 • C because the metal-organic precursors used as sources during the ALD process fully decompose at high temperatures [11]. Many methods have been studied to lower the deposition temperature of HfO 2 in ALD [12][13][14][15][16]. However, in those studies, HfO 2 thin films deposited at low temperatures had problems, such as a high level of carbon impurities (5.15%-8.9% carbon impurity in HfO 2 thin films Materials 2020, 13,2008 2 of 10 deposited at 150 • C) or low density (3.7 g/cm 3 when deposited at 30 • C, 4.1 g/cm 3 at 50 • C, 4.8 g/cm 3 at 80 • C and 5.3 g/cm 3 at 100 • C); these problems cause high leakage current and poor reliability in electronic devices [12][13][14].…”

“…In the ALD process, electrochemical oxidation potential of the reactants indicates the ligand-decomposing power [21][22][23][24]. Higher oxidation potential of reactants enables the low-temperature processes because less thermal energy is required for source decomposition [16].…”

Atomic Layer Deposition of Nanolayered Carbon Films

“…A plasma-enhanced atomic layer deposition system (ALD-150LX, Kurt J. Lesker Company, Frankfurt am Main, Germany) was used to grow the carbon film in this research [42]. Methane (CH 4 ) was used as the precursor for the carbon source, and Ar/H 2 were used for both plasma and purge gases during the deposition.…”

Dielectrophoresis-Based Positioning of Carbon Nanotubes for Wafer-Scale Fabrication of Carbon Nanotube Devices

“…The process chamber had a background pressure of 2 × 10 −7 Torr, and the film thickness was controlled by an INFICON deposition monitor. An ALD-150LX system (Kurt J. Lesker Company, Pittsburgh, USA) was used to grow the hafnium dioxide (HfO 2 ) thin film as the gate oxide in the fabrication of CNTFETs [ 36 , 37 ]. A set of four-piece photo masks was designed and used for the fabrication of the carbon nanotube field-effect transistors (CNTFETs).…”