Real-Time measurement & study of reduction process of copper oxide film by formic acid

This paper reports on the results of a real-Time measurement of a copper-oxide reduction process using formic acid. For the observation, an experiment system combining an ellipsometer and vacuum chamber was constructed. Measurements were performed for both native oxide and thermal oxide, and activation energy values were calculated from the temperature dependence of the reduction rates. Activation energy values of 61.9 kJ/mol and 100.6 kJ/mol were obtained for the native oxide and the thermal oxide, respectively. In addition, it was confirmed that Cu2O is formed in both oxides with different distributions in the depth direction. From the results, it is expected that the difference in activation energy can be attributed to the difference in energy of oxygen diffusing from the depths of the substrate to its surface.