Browse Prior Art Database

High Tc Superconducting Hybrid Microelectronic Package

IP.com Disclosure Number: IPCOM000106143D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 4 page(s) / 115K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+5]

Abstract

Application of High Temperature Superconductors (HTSC) with enhanced capabilities for high speed and high frequency signal processing systems is currently being addressed. Key to the development of hybrid microelectronic devices is the compatibility of the HTSC materials and their required substrates and dielectric materials.

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High Tc Superconducting Hybrid Microelectronic Package

      Application of High Temperature Superconductors (HTSC) with
enhanced capabilities for high speed and high frequency signal
processing systems is currently being addressed.  Key to the
development of hybrid microelectronic devices is the compatibility of
the HTSC materials and their required substrates and dielectric
materials.

      Disclosed is a method that allows the use of superconducting
lines and interconnects together with a low dielectric constant
insulator, provides good thermal matching between the two, and allows
for multi-level packaging.  The technique utilizes a new type of
polyimide, BPDA-PDA (1), that provides

1.  A low dielectric constant, i.e., 3.5 @ 1 KHz

2.  A Thermal Coefficient Of Expansion (TCE) of 5 to 15 ppm from 20
    to 200 C

3.  Excellent passivation
and allows for fabrication of lines and multi-level interconnects
using both film and board forms.

      The disclosed method, outlined in Fig. 1 depicts the
fabrication technique.  A soluble halide substrate, e.g., Lithium
Fluoride, which has a lattice parameter close to that of the HTSC to
allow for potential texturing or pseudo-epitaxy is selected and a
HTSC film is deposited  by laser ablation, for example, (Fig. 1a).
Using a wet or dry process, the conducting line patterns are defined
using standard photolithographic techniques on the halide substrate
(Fig. 1b).  A BPDA-PDA polyimide film is spin coated over the
patterned superconducting lines with a nominal thickness on the order
of 2 to 3 microns (Fig. 1c) and a polyimide carrier board is placed
over the spun polyimide layer, (Fig. 1d).  The sandwich structure is
then cured at 350 to 400 C to cross link the spun polyimide film.
Once cured, the package is submerged in a solvent such as water,
which dissolves the halide substrate, leaving the structure shown in
Fig. 1e.

      The disclosed method outlined above can be modified by the
procedure illustrated in Fig. 2 to produce a multilevel structure
with x-y wiring levels connected by superc...