Electron-assisted chemical etching of oxidized chromium

Electron-assisted chemical etching of oxidized chromium, CrOx, has been studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM). Two model substrates were used—10 nm CrOx deposited on Si(1 0 0) that was covered with either native oxide or a 20 nm Au/Pd alloy film. Using chlorine and/or oxygen as etching gases, the experiments were conducted in a customized high vacuum system, equipped with a high density electron source and a low pressure reaction cell. On both substrates, electron-assisted chemical etching of CiOx was detected by SEM, EDS and AFM. Making the method questionable for etching applications, there is substantial substrate damage associated with the etching. The SEM images indicate strongly inhomogeneous material removal, apparently initiated and propagated from specific but unidentified sites. In the experiments involving the Au/Pd film, there was phase separation of Au and Pd, and dewetting to form metallic islands. AFM data show that the etched holes were as deep as 200 nm, confirming relatively rapid etching of the Si substrate after the top layer of Cr oxide was removed.