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Self-aligned patterning of tantalum oxide on Cu/SiO2 through redox-coupled inherently selective atomic layer deposition

Summary

Researchers developed a new manufacturing technique using atomic layer deposition to precisely deposit a thin oxide coating on silicon dioxide while avoiding unwanted deposition on copper surfaces. This method uses an ethanol reduction step to keep the copper from oxidizing and accepting the coating material. When tested on tiny copper and silicon dioxide patterns about 100 nanometers across, the coating grew only where desired, achieving perfect selectivity without any defects.

Background

Atomic-scale precision alignment is critical for next-generation nanoelectronics fabrication. Traditional top-down manufacturing approaches face challenges with edge-placement error and process complexity. Selective atomic layer deposition (ALD) offers a promising technique for achieving atomic-scale precision alignment on pre-patterned substrates.

Objective

To develop a redox-coupled inherently selective ALD method for tantalum oxide deposition that achieves selective growth on oxide surfaces while inhibiting nucleation on copper. The goal is to demonstrate self-aligned patterning on Cu/SiO2 nanopatterns with high selectivity and minimal defects.

Results

The optimized ABC-type (EtOH-Ta(NtBu)(NEt2)3-H2O) ALD process achieved 100% selectivity with no observable growth on copper and film thickness exceeding 5-6 nm on SiO2. Selective deposition was successfully demonstrated on Cu/SiO2 nanopatterns with ~100 nm pitch without mushroom growth at edges or nucleation defects in the copper region.

Conclusion

Redox-coupled inherently selective ALD provides a streamlined bottom-up approach for self-aligned nanomanufacturing without requiring inhibitor passivation and removal steps. This method demonstrates one of the highest reported selectivities for oxide deposition on metal/dielectric patterns and offers advantages for future integrated circuit scaling.
  • Published in:Nature Communications,
  • Study Type:Experimental Research,
  • Source: 10.1038/s41467-023-40249-2, PMID: 37495604
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