SUB MICRON AREA Nb/A10x/Nb TUNNEL JUNCTIONS FOR SUBMM MIXER APPLICATIONS

The 3rd International Symposium on Space Terahertz Technology

HG. LeDuc ; B. Bumble ; S.R. Cypher ; A.J. Judas* ; .11A. Stern Center for Space Microelectronics

Others  :  http://www.nrao.edu/meetings/isstt/papers/1992/1992408418.pdf
PID  :  28584

来源: CEUR

【 摘 要 】

In this paper, we report on a fabrication process developed for submicron area tunnel junctions. We have fabricated NIVA10x/Nb tunnel junctions with areas down to 0.1 aum2 using these techniques. The devices have shown excellent performance in receiver systems up to 500 GHz and are currently in use in radio astronomy observatories at 115, 230, and 500 GHz. The junctions are fabricated using a variant of the self-aligned-liftoff trilayer processlwith modifications for electron beam lithographic patterning of junction areas. In brief, the technique involves patterning submicron holes in PMMA using electron beam lithography. The negative of this pattern is formed by thermal deposition and liftoff of chromium metal using this PIVIMA stencil. The chromium pattern is transferred to an underlying polyimide film using oxygen RIE. Junctions are formed by PIE using a gas mixture containing CCl2F2 and electrically isolated with thermally evaporated silicon monoxide. Contact wiring and coupling/tuning structures are patterned by RIE.