Patent GB-1500313-A (GB)
Title: Micro-electronic modules
IPC: H01L23/532
Filed: 1975-04-10
Abstract: 1500313 Microelectronic modular assemblies INTERNATIONAL BUSINESS MACHINES CORP 10 April 1975 [30 May 1974] 14679/75 Heading H1R A three-dimensional microelectronic module (Fig. I) enabling reduction of signal propagation delay times comprises a support 10 carrying plural circuit bearing means 11 spaced apart parallelly perpendicular to support 10 and to a second support 12 spaced parallel thereto. The means 11 are clearly spaced in pairs and carry on a surface thereof integrated circuits which may comprise, e.g. superconductive circuitry including Josephson tunnel devices extending two-dimensionally. Interconnection means are carried on supports 10, 11 and heat is dissipated by the ambient medium, which may be liquid helium or nitrogen. Each means 11 thus comprises a chip (Figs. 2a to 2g) with an integrated circuit on a surface thereof, and in manufacture a Si or glass wafer is partially slitted at 17 in parallel rows spaced by a dimension of the required chips, which have cut out boundaries 18, 19 separating, e.g. chips 11<SP>1</SP>, 11<SP>11</SP>. The slits may be formed, e.g. by electron beam drilling or etching and thereafter filled with LMP superconductive solder to form contact lands, and the wafer surfaces are polished flat for reception of vacuum photolitho deposition. The back surface is then coated with a thin insulant film 21 and the front surface with integrated superconductive circuitry 20 to which the filled slits 17<SP>1</SP> form contact lands. The wafers are then cut along lines 18, 19 to form plural chips (Fig. 2c). A supporting wafer 10 (Fig. 2d) of material having similar coefficient of expansion to the chips is grooved at 73 to present surfaces 15, 15<SP>1</SP> by machining or pressing, and two rows of slits 16 are cut into surfaces 15 by electron beam drilling or etching, while the ungrooved side is polished for photolitho deposition of, e.g., integrated circuit wiring 24 of superconductive film (Fig. 2f). Thereafter the wafer is cut to form plural supports 10 wherein, e.g., Nb contact foils 22 are positioned in the slots to protrude above surface 15 and extend to the interconnections 24 on the reverse surface (Fig. 2e). The chips 11 are mounted in the supports 10 in pairs with contact lands 17<SP>1</SP> contacting foils 22 and reflow soldered, with superconductive circuitry 20 on one face and insulant layers 21 on the other (Fig. 2g). The support 12 is a mirror image of support 10. In a modification, grooves 13 may be dispensed with and slots 16 extended through the entire thickness of support 10. Connecting pins may be positioned on support 10 for connection to a printed circuit card. Alternatively (Fig. 3) the circuit bearing means 11 may have plural edge contact lands 17<SP>1</SP> and plural integrated circuit chips 31 solder reflow mounted thereon and electrically connected thereto over superconductive wiring 32 on the chip and support surfaces; to form a plural microcircuit module supported as in Fig. 1. In a further modification (Figs. 4a to 4e, not shown) plural circuit carrying means are spaced apart by intervening supports and carry superconductive integrated circuits on at least one surface thereof; the supports carrying interconnection means; the module being immersed, e.g. in liquid helium or nitrogen circulating between the circuit carriers. The contact lands are fabricated by filling drilled holes with superconductive solder in the circuit carrying and support means; alternatively by solder filled grooves; the interconnections being completed by solder reflow. The module may carry pins for connection to a printed circuit card.