Review—Atomic Layer Deposition of Silicon Dioxide Thin Films

This article provides a critical review of published experimental data for silicon dioxide thin films deposited using cyclic technologies, including thermally-activated (TA) and plasma-enhanced (PE) Atomic Layer Deposition (ALD). The studied precursors (cyanates, silicon chlorides, oxygen-containing reactants, amino silanes and heterocyclic compounds) have been analyzed historically with a search depth of about 25 years. The focus is on the aspects of film growth. The aminosilane precursor group has been comprehensively analyzed for the TA-ALD and PE-ALD processes using ozone and oxygen as oxidants, respectively. The deposition rates are on the level of 0.05–0.15 nm per process cycle on average. The deposition rate of PE-ALD shows gradual decrease with temperature for all investigated precursors. For TA-ALD processes, the deposition temperature decreases and the deposition rates increase with a decrease in the number of amino groups in the silane molecule, and with an increase in the ozone dose. Problems and solutions to the problem of thin film conformality in ALD processes are analyzed. Assumptions are made about the possible prospects for investigating TA-ALD processes using monosilane, oxygen and nitrous oxide at low deposition temperatures.