High-Performance MIM Capacitors for a Secondary Power Supply Application.

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Microstructure is critical for high-performance energy devices.
• Metal-insulator-metal (MIM) capacitors are key components in energy storage.
• Microelectromechanical systems (MEMS) technology offers advanced fabrication capabilities.

Purpose of the Study:

• To develop a high-performance, three-dimensional (3D) silicon-based metal-insulator-metal (MIM) capacitor.
• To enhance capacitance density through area enlargement using deep trench structures.
• To investigate the performance characteristics and underlying physical mechanisms of the fabricated capacitor.

Main Methods:

• Fabrication of a 3D Si-based MIM capacitor using microelectromechanical systems (MEMS) technology.
• Area enlargement achieved via deep reactive ion etching (DRIE) to create high aspect ratio deep trenches.
• Deposition of Al₂O₃ dielectric and W/TiN electrode layers using atomic layer deposition (ALD).

Main Results:

• A large capacitor area of 2.45 × 10³ mm² was realized in a high aspect ratio (30:1) deep trench structure.
• The capacitor exhibited a high breakdown voltage of 34.1 V and a high breakdown electric field of 6.1 ± 0.1 MV/cm.
• Achieved moderate energy density (≥1.23 mJ/cm²), low leakage current (10⁻⁷ A/cm² at 22.5 V), and low quadratic voltage coefficient of capacitance (≤63.1 ppm/V²).

Conclusions:

• The 3D Si-based MIM capacitor demonstrates excellent performance metrics suitable for energy storage.
• Poole-Frenkel emission and trap-assisted tunneling mechanisms explain the observed high energy supply and low leakage current.
• The developed capacitor holds potential for application as a secondary power supply.