Microfabrication processes for high-Tc superconducting films

Microfabrication processes for Y-Ba-Cu-O films have been investigated, using ion-beam techniques. High-Tc superconducting lines as narrow as 0.8 μm have been fabricated from epitaxial YBa2Cu3O7-y films by Ar ion-beam etching (IBE), combined with focused ion-beam (FIB) lithography. The resulting lines, 1.3 μm wide and 2 mm long, showed a zero resistance temperature of 81 K and a critical current density of 1.9 x 104 A/cm2 at 77.3 K. Maskless etching was carried out using 130-keV au+ focused ion-beam (FIB) with a 0.1-μm-diameter beam. A 50-nm-thick film was patterned into 0.3-μm-wide lines at a dose of 5 x 16 ions/cm2. In comparison with Ar IBE, Cl2 reactive ion-beam etching (RIBE) exhibited an enhancement effect in sputtering yield. Ion implantation with 300-keV Si++ FIB also indicated the possibility to produce submicrometer patterns by selectively modifying film properties from superconductive to normal or insulting