3D Numerical Simulation of a Z Gate Layout MOSFET for Radiation Tolerance

Area of Science:

• Semiconductor Device Physics
• Radiation Effects in Electronics
• Microelectronics Engineering

Background:

• Total Ionizing Dose (TID) effects degrade semiconductor device performance.
• Existing radiation-hardened layouts like enclosed gates have limitations.
• Optimizing NMOSFET layout is crucial for reliable operation in radiation environments.

Purpose of the Study:

• To propose and evaluate a novel Z gate layout for NMOSFETs with improved TID tolerance.
• To compare the radiation hardness of the Z gate layout against single gate and enclosed gate layouts.
• To analyze the impact of TID on threshold voltage and leakage current for different NMOSFET layouts.

Main Methods:

• Simulation of three NMOSFET layouts (Z gate, single gate, enclosed gate) using Sentaurus 3D TCAD.
• Comparison of transfer characteristics (Id-Vg) to assess radiation tolerance.
• Extraction and analysis of threshold voltage shift and leakage current increment under various radiation doses.

Main Results:

• The proposed Z gate layout demonstrates superior TID tolerance compared to conventional layouts.
• Radiation hardening of the Z gate layout is achievable with a specific shallow trench isolation (STI) charge density.
• The Z gate layout offers advantages in terms of footprint, W/L design flexibility, and gate capacitance.

Conclusions:

• The Z gate NMOSFET layout presents a promising solution for enhanced radiation hardness.
• This novel layout provides a balance of performance, size, and radiation tolerance.
• Further investigation into STI charge density optimization can enhance radiation hardening capabilities.