Tunable-performance all-oxide structure field-effect transistor based atomic layer deposited Hf-doped In2O3 thin...

Area of Science:

• Materials Science
• Semiconductor Physics
• Nanotechnology

Background:

• Relocating transistors to the back-end-of-line (BEOL) enables new functionalities and die area.
• Oxide semiconductors, particularly Indium Oxide (In2O3), are promising for BEOL applications.
• High intrinsic carrier concentration in In2O3 limits its use.

Purpose of the Study:

• To develop a method for tuning the intrinsic carrier concentration of In2O3.
• To investigate Hafnium (Hf) doping in In2O3 (IHO) films for improved transistor properties.
• To fabricate and characterize all-oxide transistors using an optimized IHO material.

Main Methods:

• Atomic Layer Deposition (ALD) was used to deposit Hf-doped In2O3 (IHO) films.
• The doping concentration of Hf was systematically varied to tune film properties.
• All-oxide transistors were fabricated using an optimized In2O3:HfO2 ratio (10:1) with an Au-free process.

Main Results:

• Hf doping effectively reduced the intrinsic carrier concentration in In2O3 films.
• The optimized In2O3:HfO2 (10:1) transistors demonstrated high on-current (249 µA) and field-effect mobility (13.4 cm²/V·s).
• Excellent on/off ratio (>10^6) and stability under bias stress were achieved.

Conclusions:

• Hf doping via ALD is an effective strategy to control carrier concentration in In2O3.
• The developed IHO material and all-oxide transistors show significant potential for BEOL integration.
• This work advances the development of robust and high-performance all-oxide transistors for future electronic devices.