Area-Selective Deposition of AlO and Al-Silicate for Fully Self-Aligned Via Integration

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Manufacturing

Background:

• The demand for high-performance electronics drives the need for advanced fabrication techniques beyond traditional top-down patterning.
• Area-selective deposition (ASD) is a critical self-aligned fabrication method for continued device scaling, with the fully self-aligned via (FSAV) scheme being a key application.
• Existing low-κ dielectric deposition processes are incompatible with organic masks (self-assembled monolayers) required for dielectric-on-dielectric ASD due to high temperatures or harsh oxidizers.

Purpose of the Study:

• To develop and evaluate novel atomic layer deposition (ALD) processes for AlO and Al-silicate suitable for area-selective deposition (ASD).
• To enable dielectric-on-dielectric ASD for the realization of fully self-aligned via (FSAV) structures.
• To assess the material properties and electrical performance of the developed low-κ dielectric films.

Main Methods:

• Utilized dimethylaluminum isopropoxide and H₂O for AlO ALD, and introduced 2,2-dimethoxy-1,6-diaza-2-silacyclooctane (DMDAcO) pulses for Al-silicate ALD.
• Demonstrated process selectivity on 50 nm Cu/SiO₂ structures using octadecanethiol-derived self-assembled monolayers (SAMs) as inhibitors.
• Employed scanning/transmission electron microscopy (SEM/TEM) for structural analysis and X-ray photoelectron spectroscopy (XPS) for film composition and purity assessment.

Main Results:

• Achieved selective AlO and Al-silicate deposition, inhibiting nucleation on SAM-masked copper lines.
• Characterized high-purity AlO films and confirmed DMDAcO-ligand incorporation in Al-silicate films.
• Planar capacitor structures with Al-silicate films showed a low dielectric constant (κ ≈ 5.3), high breakdown voltage (6.0 V), and high acceleration field factor (32.4).

Conclusions:

• The developed AlO and Al-silicate ALD processes are suitable for dielectric-on-dielectric ASD, paving the way for FSAV realization.
• The Al-silicate film demonstrates promising low-κ dielectric properties for advanced semiconductor applications.
• This work overcomes a significant barrier in integrating ASD for high-volume manufacturing of next-generation electronic devices.