Kinetics of cuprous oxide etching with β-diketones in Supercritical CO2

Cuprous oxide films (Cu2O) supported on Cu or on SiO2 were etched using solutions of β-diketones including 1,1,1,5,5,5-hexafluoroacetylacetone, 2,2,6,6-tetramethyl-3,5-heptanedione and 2,2,7-trimethyl-3,5-octanedione (TMOD) in supercritical carbon dioxide at temperatures between 80 and 150 °C and pressures between 20 and 27.5 MPa. The films and etched substrates were analyzed by X-ray photoelectron spectroscopy depth profiling, field emission scanning electron microscopy and spectroscopic ellipsometry. Each of the etching agents was effective. Etching kinetics using TMOD were measured at 100, 125 and 150 °C. At 150 °C the etch rate was 1.5 nm/min. Based on the activation energy obtained from the studies (66 kJ/mol), etching rates of greater than 10.0 nm/min can be obtained at 200 °C.