High current densities and associated failure mechanisms in long narrow Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ lines

The use of high temperature superconducting thin films in chip-to-chip interconnects requires the fabrication of long, narrow lines capable of carrying high current density on large area films. The capability of Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ thin films and patterning technology were studied for 0.65 /spl mu/m-thick films prepared on 2-and 3-inch diameter LaAlO/sub 3/ wafers. For 15, 12, and 10 /spl mu/m wide lines 1.8-2.0 m in length, critical current density J/sub c/ at 80 K in excess of 1.4 MA/cm/sup 2/ was achieved. Lines of length 70 cm and widths of 4 and 7 /spl mu/m yielded J/sub c/ at 80 K of 1.10 and 0.94 MA/cm/sup 2/ respectively. Patterning of long, continuous lines 2 /spl mu/m in width was difficult, but one such line 33.8 cm in length achieved a J/sub c/ of 1.2 MA/cm/sup 2/ at 70 K and another a J/sub c/ of 0.42 MA/cm/sup 2/ at 80 K. Line failure at high current density occurred through two mechanisms. Localized melting at high current density resulted in small localized line discontinuities. A second mechanism, postulated to be arcing, was characterized by melting and disfiguration over line lengths of up to several centimeters.< >