Browse Prior Art Database

Direct Light-Chip Interconnection Scheme Accommodating Flip-Chip Bonding

IP.com Disclosure Number: IPCOM000119261D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Arjavalingam, G: AUTHOR [+4]

Abstract

Disclosed is a scheme for providing parallel, byte-wide optical interconnection to flip-chip (or C4)-mounted silicon-integrated circuits. The arrangement is represented schematically in the attached figure. Optical fibers are brought into the module through the TCM cap. Graded-index (GRIN) lenses attached to the ends of fibers are, in turn, attached to the back surface of the ICs. Index matching grease is used to reduce the optical losses in this connection. The GRIN lenses focus the light exiting the fibers onto the detectors on the front (active) surface of the circuit.

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Direct Light-Chip Interconnection Scheme Accommodating Flip-Chip
Bonding

      Disclosed is a scheme for providing parallel, byte-wide
optical interconnection to flip-chip (or C4)-mounted
silicon-integrated circuits.  The arrangement is represented
schematically in the attached figure.  Optical fibers are brought
into the module through the TCM cap.  Graded-index (GRIN) lenses
attached to the ends of fibers are, in turn, attached to the back
surface of the ICs.  Index matching grease is used to reduce the
optical losses in this connection.  The GRIN lenses focus the light
exiting the fibers onto the detectors on the front (active) surface
of the circuit.

      Since the band-gap of silicon is 1.1 eV (1), it is transparent
to 1.3 mm radiation.  Consequently, light sources at or about 1.3 mm
are used in this interconnection scheme.  For instance, lasers or
light-emitting diodes (LEDs) based on InGaAsP semiconductor material
will be suitable.  The optical radiation will then traverse the IC
with little loss.  The detector can be based on Ge or SiGe
superlattice materials, and could be photoconductors, avalanche
photodetectors (APD), or PIN detectors (2).  SiGe based
heterostructure devices have been grown directly on silicon with
molecular beam epitaxy (MBE) (3) and CVD techniques (4).

      The power and ground return are electrically attached to the
detectors through C4 connections.  The detector output is directly
fed to the circuit by on-chip wirin...