Josephson integrated circuit process for scientific applications

We have developed and are regularly practicing a seven mask-level Josephson integrated circuit fabrication process tailored to dc SQUID requirements and intended for SQUID studies and other scientific applications of Josephson technology. The process incorporates low capacitance Nb/Nb 2 O 5 /PbAuIn edge junctions, PdAu shunt resistors, and a wiring pitch of 5 μm for the SQUID input coil level (which is PbAuIn). The junctions can be made as small as 2μm by 0.3μm, with a capacitance (including parasitics) of ∼0.14 pF. This process yields stable and reliable junctions and integrated circuits.

[1]  C. Neugebauer,et al.  Thin Films of Niobium for Cryotron Ground Planes , 1967 .

[2]  John Clarke,et al.  dc SQUID: Noise and optimization , 1977 .

[3]  P. Brosious.  The role of Ar+, CH+ 4 , O+ 2 and backscattered Pb+ ions during Nb/Oxide/PbAuIn edge junction fabrication , 1985 .

[4]  Mao-min Chen,et al.  Plasma etching of niobium with CF4/O2 gases , 1983 .

[5]  S. I. Raider,et al.  Nb/Nb oxide/Pb-alloy Josephson tunnel junctions , 1981 .

[6]  Vittorio Foglietti,et al.  Low-frequency noise in low 1/f noise dc SQUID's , 1986 .

[7]  C. J. Kircher,et al.  Fabrication Process for Josephson Integrated Circuits , 1980, IBM J. Res. Dev..

[8]  S. Lahiri.  Metallurgical considerations with respect to electrodes and interconnection lines for Josephson tunneling circuits , 1976 .

[9]  Mark B. Ketchen,et al.  Practical DC SQUIDs with extremely low 1/f noise , 1985 .

[10]  R. F. Broom,et al.  Josephson junctions of small area formed on the edges of niobium films , 1980 .

[11]  J. Greiner.  Josephson Tunneling Barriers by rf Sputter Etching in an Oxygen Plasma , 1971 .

[12]  M. Ketchen.  DC SQUIDs 1980: The state of the art , 1981 .

[13]  E. E. Latta,et al.  Barrier composition and electrical properties of high-quality all-niobium Josephson tunnel junctions , 1983 .

[14]  T. Kuan,et al.  Structure of a Nb oxide tunnel barrier in a Josephson junction , 1982 .

[15]  A. Kleinsasser.  Relationship between beam and junction parameters in ion beam processed Josephson devices , 1985 .

[16]  Robert A. Buhrman,et al.  High‐quality submicron niobium tunnel junctions with reactive‐ion‐beam oxidation , 1980 .