Excimer laser projection-patterned deposition of Al via photolytically driven decomposition of trialkylamine alane as adsorbate precursor

Abstract

Aluminum films have been deposited from trimethylamine alane (CH₃)₃N · AlH₃ and triethylamine alane (C₂H₅)₃N · AlH₃ precursors on Al₂O₃, GaAs and quartz substrates using XeCl (λ=308 mn) and KrF (λ=248 nm) excimer lasers. Substrate surface irradiation induces the decomposition of the precursor in the adsorbed phase. The technique allows projection patterned deposition of Al at room temperature. Al deposition proceeds in two steps: surface nucleation, which is a pure photolytic process, and the succesive Al growth, which is photolytically driven but is thermally activated at low laser energy densities (<60 mJ/cm²). The nucleation process strongly depends on the substrate and laser wavelength. Mirror like Al films are deposited at rates up to about one Al monolayer per pulse which corresponds to rates up to 2 μm/min when photolyzing at 100 Hz. Al films with good adhesion and resistivities down to 7.5 μΩ cm (2.5 times bulk), were deposited. The process has good spatial selectivity. Patterns with 1 μm resolution have been generated.