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

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 I_on-I_off ratios (>10⁸) and low off-currents (<10⁻¹¹ A). In addition, ZrO₂-based TFT showed high reliability against a negative V_th 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.