Measurement of surface roughness and ion-induced secondary electron emission coefficient of MgO films prepared by high-pressure sputter deposition

Abstract

Magnesium oxide (MgO) films were prepared by RF sputter deposition technique, and their secondary electron emission (SEE) coefficient was examined in relation to film thickness and surface morphology. The optical constant and film thickness were evaluated from the optical transmission spectroscopy for samples prepared on the glass substrate. The ion-induced SEE coefficient was measured for MgO films deposited on Si substrates of both mirror-polished (root mean square (RMS) roughness <1 nm) and etched-rough (RMS roughness ∼40 nm) faces, in an XPS apparatus using the primary ion beam of Ar+ at 1 keV. The SEE coefficient was as large as 2.5 for 100 nm MgO films, and did not depend strongly on the process pressure nor the roughness of the silicon substrate. Samples of 200 nm MgO thickness showed a current instability in the SEE measurement, probably due to the charge up.