Growth behavior and properties of atomic layer deposited tin oxide on silicon from novel tin(II)acetylacetonate precursor and ozone

In this work, a novel liquid tin(II) precursor, tin(II)acetylacetonate [Sn(acac)₂], was used to deposit tin oxide films on Si(100) substrate, using a custom-built hot wall atomic layer deposition (ALD) reactor. Three different oxidizers, water, oxygen, and ozone, were tried. Resulting growth rates were studied as a function of precursor dosage, oxidizer dosage, reactor temperature, and number of ALD cycles. The film growth rate was found to be 0.1 ± 0.01 nm/cycle within the wide ALD temperature window of 175–300 °C using ozone; no film growth was observed with water or oxygen. Characterization methods were used to study the composition, interface quality, crystallinity, microstructure, refractive index, surface morphology, and resistivity of the resulting films. X-ray photoelectron spectra showed the formation of a clean SnO_x–Si interface. The resistivity of the SnO_x films was calculated to be 0.3 Ω cm. Results of this work demonstrate the possibility of introducing Sn(acac)₂ as tin precursor to deposit conducting ALD SnO_x thin films on a silicon surface, with clean interface and no formation of undesired SiO₂ or other interfacial reaction products, for transparent conducting oxide applications.