Comparative study on growth characteristics and electrical properties of ZrO2 films grown using pulsed plasma-enhanced chemical vapor deposition and plasma-enhanced atomic layer deposition for oxide thin film transistors

Abstract

The deposition of high-quality ZrO2 films has been achieved using both pulsed plasma-enhanced chemical vapor deposition (P-PE-CVD) and plasma-enhanced atomic layer deposition (PE-ALD) with (C5H5)Zr[N(CH3)2]3 as a Zr precursor. The authors compared the growth characteristics, chemical compositions, and electrical properties of P-PE-CVD and PE-ALD ZrO2 prepared under various deposition conditions. The ZrO2 films prepared using both methods showed high purity and good stoichiometry. Electrical characterization of a metal-oxide-semiconductor capacitor utilizing the ZrO2 films showed that PE-ALD films have a relatively lower leakage current than P-PE-CVD films, whereas the dielectric constant, interface trap density, and hysteresis of both films are similar. Applying both methods, the electrical properties of ZrO2 films were also evaluated using In–Ga–Zn–O thin-film transistors (TFTs), which showed a good device performance in terms of high Ion-Ioff ratios (>108) and low off-currents (<10−11 A). In addition, ZrO2-based TFT showed high reliability against a negative Vth shift. Based on the self-limiting growth characteristics and electrical properties of P-PE-CVD, the authors found that the P-PE-CVD process results in electrical properties comparable to those of PE-ALD ZrO2 films. Thus, the authors believe that P-PE-CVD can be an alternative process to PE-ALD for future electronic device applications, especially for display applications due to its good electrical properties with high throughput.