In Situ Thermal Atomic Layer Etching for Sub-5 nm InGaAs Multigate MOSFETs.

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Ternary III-V compound semiconductors like InGaAs and InAlAs are crucial for advanced electronic devices.
• Precise control over etching processes is essential for fabricating nanoscale structures.

Purpose of the Study:

• To demonstrate thermal atomic layer etching (ALE) on ternary III-V compound semiconductors.
• To investigate the application of thermal ALE in fabricating nanostructures and advanced electronic devices.

Main Methods:

• Sequential, self-limiting fluorination using hydrogen fluoride (HF) and ligand-exchange reactions with dimethylaluminum chloride (DMAC).
• Investigation on planar surfaces and 3D nanostructures, including vertical nanowires (VNWs).
• Integration with in situ atomic layer deposition (ALD) for fabricating complex structures.

Main Results:

• Achieved thermal ALE on InGaAs and InAlAs with radial etch rates of 0.24 and 0.62 Å/cycle on VNWs at 300 °C.
• Demonstrated process with no increase in surface roughness after 200 cycles, showing selectivity and orientation dependence.
• Fabricated InGaAs gate-all-around structures down to 3 nm width and n-channel InGaAs FinFETs with record performance.

Conclusions:

• Thermal ALE is a viable and promising technique for precise etching of III-V semiconductors.
• The developed ALE-ALD process enables fabrication of high-quality nanoscale devices with sharp interfaces.
• Thermal ALE shows significant potential for high-volume manufacturing of advanced semiconductor devices.