Simulation Study on Capacitive Characteristics of Three-Dimensional Trench Array MOS Capacitor Structure

• 1、School of Integrated Circuit, Dalian University of Technology, Dalian, 116600
• 2、Dalian Dalikepu Technology Co., Ltd.

Abstract：To improve the capacitance density per unit area of silicon-based capacitors, a numerical simulation study of a three-dimensional trench array MOS capacitor structure was conducted. Using a parallel-plate MOS capacitor as a control structure, a PolySi/HfO?/Si device model was constructed using the Sentaurus TCAD platform, and a three-dimensional circular aperture array trench MOS capacitor structure was established using a parametric method. Under unified process parameters, low-frequency C-V characteristic simulations were performed on both structures. Simulation results also systematically analyzed the influence of key structural parameters such as trench depth H, dielectric layer thickness t, and trench radius R on the capacitance density per unit area. The simulation results show that compared to the traditional parallel-plate MOS capacitor structure, the three-dimensional trench array structure significantly improves the capacitance density by increasing the effective electrode area on the sidewalls. Under the conditions of H=3μm, t=15nm, and R=0.3μm, the capacitance density increases from 14.83 nF/mm2 to 115.89 nF/mm2. Further research revealed that increasing the trench depth and decreasing the dielectric layer thickness both significantly improve capacitance density. While maintaining the array period ratio P=3R, reducing the trench radius is beneficial for increasing the array fill rate, thereby enhancing capacitance performance per unit area. The results demonstrate that three-dimensional trench array structures have significant advantages in improving the capacitance density of silicon-based capacitors, providing a theoretical reference for the structural design and optimization of high-density integrated capacitor.

Keywords： Microelectronics MOS capacitors three-dimensional trench structure capacitance density Sentaurus TCAD