Selective Gas-Phase Functionalization of SiO₂ and SiN Surfaces with Hydrocarbons

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• Area-selective atomic layer deposition and etching require precise functionalization of dielectric surfaces.
• Plasma-deposited silicon dioxide (SiO2) and silicon nitride (SiN) are key materials in microelectronics.

Purpose of the Study:

• To identify and characterize precursors for selective gas-phase functionalization of SiO2 and SiN surfaces with hydrocarbons.
• To investigate the reaction mechanisms of these precursors with -OH-terminated SiO2 and -NH2-terminated SiN surfaces.
• To achieve high selectivity for area-selective processes.

Main Methods:

• In situ surface infrared spectroscopy was used to study reaction mechanisms.
• Gas-phase functionalization using cyclic azasilanes and aldehydes.
• Analysis of surface coverage and reaction pathways.

Main Results:

• Cyclic azasilanes selectively functionalize SiO2 over SiN with a selectivity of ~5.4 at 70 °C via ring-opening reactions with -OH groups.
• Aldehydes selectively functionalize SiN over SiO2, with minimal reaction on SiO2.
• Grafted surface coverages of ~3.3 × 10^14 cm^-2 for azasilanes and ~9.8 × 10^14 cm^-2 for aldehydes were determined.

Conclusions:

• Developed hydrocarbon precursors enable selective surface functionalization of SiO2 and SiN.
• The identified precursors and mechanisms are crucial for advancing area-selective atomic layer deposition and etching.
• Tailored surface chemistry provides a pathway for advanced semiconductor fabrication.