Low Temperature Atomic Layer Deposition of Tin Oxide

Abstract

Atomic layer deposition (ALD) of tin oxide (SnOx) films was achieved using a newly synthesized tin precursor and hydrogen peroxide. We obtained highly pure, conductive SnOx films at temperatures as low as 50 °C, which was possible because of high chemical reactivity between the new Sn precursor and hydrogen peroxide. The growth per cycle is around 0.18 nm/cycle in the ALD window up to 150 °C, and decreased at higher temperatures. Self-limited growth was demonstrated for both the Sn and O precursors. Thickness is linear in the number of cycles, with an induction period of not more than a few cycles. Rutherford backscattering spectroscopy (RBS) and X-ray photoelectron spectroscopy (XPS) measurements showed that the composition ratio of O/Sn is ∼2 and that the films do not contain any detectable carbon or nitrogen impurities. X-ray and electron diffraction analyses identified crystallites of SnO2 with the rutile structure and average grain size 5−10 nm. The density of the films is 83% of the bulk rutile phas...