AVS 66th International Symposium & Exhibition
    Thin Films Division Tuesday Sessions
       Session TF+AP-TuM

Paper TF+AP-TuM4
Effect of Co-Reactant on the Atomic Layer Deposition of Copper Oxide

Tuesday, October 22, 2019, 9:00 am, Room A124-125

Session: ALD and CVD: Precursors and Process Development
Presenter: Jason Avila, U.S. Naval Research Laboratory
Authors: J.R. Avila, U.S. Naval Research Laboratory
N. Nepal, U.S. Naval Research Laboratory
V.D. Wheeler, U.S. Naval Research Laboratory
Correspondent: Click to Email
Atomic layer deposition (ALD) of copper oxide presents a powerful opportunity to grow p-type semiconductor material for a wide variety of applications such as transparent conducting oxide, solar fuels catalysis, and power devices. There are, however, very few ALD processes to facilitate the growth of copper oxide. Cu(II) bis(dmiethylamino-2-propoxide) (Cudmap) has previously been used to grow copper metal using a reducing source such as tertiary butyl hydrazine.1,2 Cudmap has also been demonstrated to grow Cu2O using water as a co-reactant, self-reducing from Cu(II) to Cu(I) in the presence of water.3 This study will examine the effect of ALD co-reactants, ozone and water, on the copper oxidation state of copper oxide films grown using Cudmap.

Copper oxide films were grown in a Veeco Savannah ALD reactor using Cudmap and ozone or water at 150 °C on Si and c-plane sapphire. This is the first experimental demonstration of CuO films using Cudmap and ozone. Using ozone, a growth rate of 0.18 Å/cycle was achieved at 150 °C, far higher than the measured growth rate of 0.04 Å/cycle when using water. Since growth rates are still quite slow, a vapor assisted precursor delivery system for the Cudmap was implemented and its ability to achieve higher growth rates will be presented.

XPS was able to confirm the presence of only the Cu(II) oxidation state with a Cu/O ratio of 1, verifying the deposition of CuO films. For comparison, films grown with water show the presence of only Cu(I) oxidation state and have a nearly stoichiometric with a Cu/O ratio of 2:1, confirming the deposition of Cu2O films. AFM also indicated uniform, continuous film growth, independent of co-reactant, for films as thin as 2 nm. However, for a similar thickness, CuO films deposited with ozone were rougher than Cu2O films grown with water. In addition to these initial results, comparison of the optical and electrical properties of the different copper oxide films for p-type semiconductor applications will be presented.

References

(1) Väyrynen, K.; Mizohata, K.; Räisänen, J.; Peeters, D.; Devi, A.; Ritala, M.; Leskelä, M. Chemistry of Materials 2017, 29, 6502.

(2) Kalutarage, L. C.; Clendenning, S. B.; Winter, C. H. Chemistry of Materials 2014, 26, 3731.

(3) Avila, J. R.; Peters, A. W.; Li, Z.; Ortuno, M. A.; Martinson, a. B. F.; Cramer, C. J.; Hupp, J. T.; Farha, O. Dalton Transactions 2017, 46, 5790.