부산대학교 도서관

We have developed a superlattice structure (SLS) of HfO2 and Al2O3 high- ${k}$ dielectrics by high-volume batch atomic layer deposition on a 200 mm platform. The SLS forms a hafnium aluminate (Hf1-xAlxO) alloy at deposition temperature and presents superior electrical properties as a metal-insulator-metal (MIM) capacitor. Among the samples, an Al mole fraction of ~0.31 demonstrates the highest capacitance density ( ${C} _{p} {D}$ ) of 12.46 fF/ $\mu \text{m}^{{2}}$ and dielectric constant, $\kappa >$ 22, 2% better than HfO2. A higher Al mole fraction of 0.56 shows a superior quadratic component ( $\alpha $ ) of voltage-coefficient of capacitance and 68% higher- $\kappa $ than an Al2O3 capacitor. Electrical measurement before and after annealing at 650 °C for 30 s illustrates the thermal stability of capacitors. The present research indicates a small amount of Al incorporation in HfO2 extends its quantization temperature by stabilizing the crystal phase by reducing oxygen vacancies and traps. It remarkably improved electrical characteristics under thermal stress compared to broken-down HfO2 capacitors under annealing. Besides, the alloy also shows improved linearity over a broad frequency range, lower leakage current, and a breakdown electric field ( ${E} _{\text {BV}}$ ) in the order of 4 MV/cm. At the same time, higher Al incorporation provides the highest ${E} _{\text {BV}}$ of ~8 MV/cm, low leakage, and near principle $\alpha $ of 210 ppm/ $\text{V}^{{2}}$ with better thermal stability. These thin multilayer SLS alloys show excellent relative capacitance variation over the voltage with high ${C} _{p} {D}$ , $\kappa $ , low leakage of 10 nA/cm2 at 3 MV/cm, suitable for higher thermal budget and interposer process integration for various high bandwidth RF and low-cost memory applications with smaller chip area.