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A Novel Atomic-Level Post-Etch-Surface-Reinforcement Process for High-Performance p-GaN Gate HEMTs Fabrication
Luyu Wang1, Penghao Zhang1, Kaiyue Zhu2
1State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent Electronics & Systems, School of Microelectronics, Fudan University, Shanghai 200433, China.
Nanomaterials (Basel, Switzerland)
|August 26, 2023
Summary
A new post-etch surface reinforcement (PESR) process repairs damage on p-GaN surfaces. This method significantly enhances the performance and reliability of p-GaN gate HEMTs, reducing on-resistance and current collapse.
Area of Science:
- Materials Science
- Semiconductor Device Physics
Background:
- Gallium Nitride (GaN) high-electron-mobility transistors (HEMTs) are crucial for power electronics.
- Etching processes for p-GaN gate fabrication can induce surface damage, degrading device performance.
- Reliable fabrication of high-performance p-GaN gate HEMTs requires effective surface damage recovery.
Purpose of the Study:
- To develop and evaluate a novel atomic-level post-etch surface reinforcement (PESR) process.
- To recover the etching-induced damage region in p-GaN for improved p-GaN gate HEMTs fabrication.
- To assess the impact of PESR on AlGaN surface morphology, crystallization, and electrical properties.
Main Methods:
- A two-step PESR process involving O2 plasma surface modification and BCl3 plasma oxide removal.
- Atomic Force Microscopy (AFM) for surface morphology characterization.
- Confocal Raman spectroscopy for lattice crystallization analysis.
- Electrical characterization including Metal-Semiconductor (MS) Schottky diodes and MIS Capacitance-Voltage (C-V) measurements.
- X-ray Photoelectron Spectroscopy (XPS) for surface chemical analysis.
Main Results:
- PESR restored AlGaN surface morphology and lattice crystallization to as-epitaxial levels.
- Significant improvements in AlGaN surface quality were observed: one order lower surface leakage and 6x lower interface density of states (Dit).
- PESR effectively removed etching-induced F-byproducts and Ga-oxides.
- Integrated PESR in p-GaN gate HEMTs fabrication led to ~20% lower on-resistance and ~25% less current collapse at 40V Vds.
Conclusions:
- The developed PESR process is highly effective in repairing p-GaN etching-induced damage.
- PESR significantly enhances the surface quality and electrical properties of AlGaN.
- The integration of PESR into p-GaN gate HEMTs fabrication boosts device performance and reliability, showing great potential for future applications.
