2024 IEEE 17th International Conference on Solid-State & Integrated Circuit Technology (ICSICT), 2024
Considering the fabrication difficulty of the highpermittivity (Hk) MOSFETs, this study proposes ... more Considering the fabrication difficulty of the highpermittivity (Hk) MOSFETs, this study proposes two aspect ratios, AR S for the n-pillars and AR I for the Hk-pillars, to optimize the specific on-resistance (R on,sp) under breakdown voltage of 1000 V. Numerical calculations by MATLAB and simulations by MEDICI demonstrate and validate that with sufficiently large permittivity ratios (K r) and optimal AR I , Hk MOSFETs can achieve lower R on,sp compared to conventional superjunction (SJ) MOSFETs. The accurate fitting function can be used to providing design instructions efficiently to make tradeoffs between fabrication difficulty and required R on,sp and BV.
A novel two-zone variational vertical doping superjunction structure with insulating layers (I-VV... more A novel two-zone variational vertical doping superjunction structure with insulating layers (I-VVDSJ) is proposed. The path length of the impact ionization integral can be shortened by the insertion of a lateral insulator layer. This allows for a higher average doping concentration and a superior specific ON-resistance (R on,sp). Two-dimensional electric field (E-field) distributions are unified for the entire structure by utilizing the sign function for optimization of R on,sp with MATLAB and MEDICI. Compared with a conventional superjunction structure for breakdown voltage (BV) larger than 700 V, the optimized R on,sp (R on,sp(opt)) can be reduced by over 27%. Formulae for the design parameters are proposed as a function of BV and aspect ratio (AR). Furthermore, R on,sp(opt) = δ(2.278 × 10-5)AR-1.295 BV 2.33 mΩ cm 2 is proposed to guide the design for the I-VVDSJ structure with the factor δ representing the junction field effect transistor effect.
A proposed optimization for high-k superjunction (H𝑘-SJ) MOSFETs focuses on reducing specific ON-... more A proposed optimization for high-k superjunction (H𝑘-SJ) MOSFETs focuses on reducing specific ON-resistance (R on,sp) in drift regions for three dimensional (3D) configurations in two cases (3DH𝑘core and 3DH𝑘shell) compared to 3D conventional SJ (C-SJ) and two dimensional Hk-SJ (2DH𝑘). Under constraints of avalanche breakdown and critical depletion, the optimized R on,sp and design parameters are determined. 3DH𝑘core achieves the lowest R on,sp of 12.43 mΩ cm 2 at 800 V breakdown voltage (BV) for small aspect ratios (AR) due to the lower breakdown electric field (𝐸-field) and impact ionization integral value, while 3DH𝑘shell excels 3DH𝑘core and 2DH𝑘 with a lower R on,sp of 6.395 mΩ cm 2 at large AR. Comparative research containing charge imbalance, temperature robustness, and switching characteristics is discussed after optimization. Taylor modeling for 3DH𝑘shell optimization is also proposed. For further manufacturing guidance, fitting and boundary curves formulas are provided.
In this paper, we propose a simulation-based novel Split-Gate Trench MOSFET structure with an opt... more In this paper, we propose a simulation-based novel Split-Gate Trench MOSFET structure with an optimized fabrication process to enhance power efficiency, switching speed, and thermal stability for high-performance semiconductor applications. Integrating High-k pillars Superjunction beneath the Split-Gate enhancing breakdown performance by reducing critical field intensity by up to 35%, the device achieves a 15% improvement in Figures of Merit (FOMs) for BV 2 /R on,sp. Dynamic testing reveals approximately a 25% reduction in both input and output capacitance, as well as gate-drain charge (Q GD). This reduction, coupled with an approximately 40% improvement in Baliga's High-Frequency Figure of Merit (BHFFOM) and over 20% increase in the New High-Frequency Figure of Merit (NHFFOM), underscores the design's suitability for high-speed, high-efficiency power electronics. Simulations examining the effects of High-k pillar depth indicate that an optimal depth of 3.5 µm achieves a balanced performance between BV and R on,sp. The influence of High-k materials on BT-Hk-SJ MOSFET performance was investigated by comparing hafnium dioxide (HfO 2), nitride, and oxynitride. Among these, HfO 2 demonstrated optimal performance across static, dynamic, and diode characteristics due to its high dielectric constant, while material choice had minimal impact, with variations kept within 5%. INDEX TERMS Breakdown voltage, figure of merit, high-k materials, power density, specific on-resistance, SGT-MOSFET, superjunction, switching time, TCAD.
This study optimizes 28 nm planar MOSFET technology to reduce
device leakage current and enhance ... more This study optimizes 28 nm planar MOSFET technology to reduce device leakage current and enhance switching speed. The specific aims are to decrease subthreshold swing (S.S.) and mitigate draininduced barrier lowering (DIBL) effect. Silvaco TCAD software is used for process (Athena) and device (Atlas) simulations. For the further development of MOSFET technology, we implemented our device (planar 28 nm n-MOSFET) with high-k metal-gate (HK/MG), lightly doped drain (LDD), multiple spacers (mult-spacers), and silicide. Simulation validation shows improvements over other 28 nm devices, with lower static power consumption and notable optimizations in both S.S. (69.8 mV/dec) and DIBL effect (30.5 mV/V).
This paper presents a comprehensive approach to enhancing submersible safety through mathematical... more This paper presents a comprehensive approach to enhancing submersible safety through mathematical modeling and decision-making frameworks. We develop models for submersible location prediction, emergency preparedness, and scenario extrapolation, including a Seawater Density Model, Submersible Mechanical Model, Bayesian Searching Model, and Extended Kalman Filter. Sensitivity analysis confirms the robustness of these models under varying conditions, making them adaptable for different marine environments. In the first section, we focus on accurately locating a submersible after communication loss. The Seawater Density Model employs a hyperbolic tangent function to model depth-dependent density in the Ionian Sea, while the Submersible Mechanical Model simulates underwater dynamics using the 4th order Runge-Kutta method. Uncertainties are addressed using an Extended Kalman Filter, enhancing accuracy, as shown by trajectory and Mean Squared Error (MSE) comparisons. In the second section, we develop a Bayesian Searching Model to efficiently locate a missing submersible. This model iteratively updates location probabilities using a bimodal Gaussian distribution. The search zone is discretized into grids, and simulations demonstrate the model’s ability to effectively narrow down the search area and improve detection success. In the third section, we adapt the models to different environments, such as the Caribbean Sea. A warning and obstacle avoidance system is introduced to manage multiple submersibles in close proximity, dynamically adjusting their paths to avoid collisions. Reliability analysis demonstrates the robustness of the models against changes in density and sudden environmental shifts, showing minimal deviation from neutral buoyancy. These results confirm the reliability and adaptability of the models for enhancing submersible safety across various marine settings
2023 15th International Conference on ASIC (ASICON) , 2023
Considering the practical applications on superjunction (SJ) structure MOSFET under different tem... more Considering the practical applications on superjunction (SJ) structure MOSFET under different temperature, a MATLAB based temperature dependent optimization approach for specific-on resistance (R on,sp) under breakdown voltage (BV) of 900 V is proposed in this paper. Based on the constraints of two-dimensional (2-D) electric field distribution and impact ionization integral, the temperature dependent models of carrier mobility, impact ionization rate, intrinsic carrier concentration, and impurity incomplete ionization are adapted. MEDICI simulation is used for verification of the results, manifesting good agreement between theoretical calculations and simulation results at low aspect ratios (AR). Application instructions are provided based on our optimization in this paper, providing compromised design choices which satisfy BV and R on,sp under different temperatures.
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Papers by Zonghao Zhang
device leakage current and enhance switching speed. The specific
aims are to decrease subthreshold swing (S.S.) and mitigate draininduced barrier lowering (DIBL) effect. Silvaco TCAD software is
used for process (Athena) and device (Atlas) simulations. For the
further development of MOSFET technology, we implemented our
device (planar 28 nm n-MOSFET) with high-k metal-gate (HK/MG),
lightly doped drain (LDD), multiple spacers (mult-spacers), and silicide.
Simulation validation shows improvements over other 28 nm devices,
with lower static power consumption and notable optimizations in both
S.S. (69.8 mV/dec) and DIBL effect (30.5 mV/V).