Role of Precursor Miscibility in Area-Selective Atomic Layer Deposition.

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Area-selective atomic layer deposition (AS-ALD) is crucial for advanced nanostructure fabrication.
• Precursor selection is a critical factor determining the success of AS-ALD processes.
• Understanding inhibitor-precursor interactions is key to achieving selective deposition on patterned surfaces.

Purpose of the Study:

• To investigate the role of different aluminum precursors in achieving area-selective ALD of Al2O3.
• To evaluate the effectiveness of benzenethiol (BT) as an inhibitor on copper and copper oxide surfaces.
• To understand the relationship between precursor structure, inhibitor interaction, and deposition selectivity.

Main Methods:

• Tested four aluminum precursors: dimethylaluminum isopropoxide (DMAI), trimethylaluminum (TMA), triethylaluminum (TEA), and triisobutylaluminum (TIBA).
• Utilized benzenethiol (BT) as an inhibitor on SiO2 substrates with Cu/CuOx features.
• Analyzed the selectivity of Al2O3 deposition and the morphology of the inhibitor layer after precursor exposure.

Main Results:

• DMAI demonstrated exceptional selectivity (>99.9%) for Al2O3 deposition on dielectric surfaces.
• Alkylaluminum precursors (TMA, TEA, TIBA) showed poor selectivity due to miscibility and degradation of the CuBT multilayer.
• DMAI's selectivity is attributed to its non-miscibility with the CuBT layer, enabling precise pattern transfer.

Conclusions:

• Precursor ligand structure significantly influences miscibility with the inhibitor layer (CuBT), impacting Al2O3 nucleation.
• DMAI is a promising precursor for high-selectivity AS-ALD of Al2O3, offering excellent pattern transfer capabilities.
• This study provides critical insights for designing effective AS-ALD processes by considering precursor-inhibitor interactions.