Control of Microstructure, Trap Levels, and Trap Distribution in HfO₂ Films Grown by Atomic Layer Deposition

Area of Science:

• Materials Science
• Solid State Physics
• Thin Film Technology

Background:

• Hafnium oxide (HfO2) films are crucial for advanced electronics but require microstructural control.
• Defects in HfO2 films act as charge traps, causing leakage current and degrading dielectric performance.

Purpose of the Study:

• To investigate the influence of substrate type on HfO2 film crystallinity using atomic layer deposition (ALD).
• To explore methods for controlling defect levels and trap distributions within HfO2 films.
• To correlate electronic structure of defects with trap measurements.

Main Methods:

• Atomic layer deposition (ALD) of HfO2 thin films on sapphire, Ga2O3, and InGaO3 substrates.
• X-ray diffraction (XRD) for crystal structure analysis.
• Electron paramagnetic resonance (EPR) and other techniques for trap characterization.

Main Results:

• Alloying Ga2O3 with Indium induced a transition from amorphous to polycrystalline HfO2 films.
• Substrate band gap difference and impurities significantly affect trap densities and depths.
• Shallow and deep trap levels and distributions were measured and controllable.

Conclusions:

• Substrate engineering via alloying is a viable strategy to control HfO2 film microstructure.
• Understanding and controlling traps is essential for optimizing dielectric properties in HfO2-based devices.
• The findings offer insights into defect management for advanced electronic materials.