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Proceedings Paper

Through-Wafer Optical Interconnects For Multi-Wafer Wafer-Scale Integrated Architectures
Author(s): L A Hornak; S K Tewksbury; M Hatamian; A Ligtenberg; B Sugla; P Franzon
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Paper Abstract

Hybrid mounting of optical components, combined perhaps with integrated optical waveguides and lenses on a large area silicon, wafer-scale integrated (WSI) electronic circuit provides one potential approach to combine advanced electronic and photonic functions. The desire to achieve a high degree of parallelism in multi-wafer WSI-based architectures has stimulated study of three-dimensional interconnect structures obtained by stacking wafer circuit boards and. providing interconnections vertically between wafers over the entire wafer area in addition to planar connections. While presently it is difficult for optical interconnects to compete with electrical interconnects in the wafer plane, it is appropriate to look at vertical optical interconnections between wafer planes since the corresponding conductive structures would be large in area and may impede system repairability. The ability to pass information optically between circuit planes without mechanical electrical contacts offers potential advantages for multi-wafer WSI or other dense three-dimensional architectures. However, while optical waveguides are readily fabricated in the plane of the wafer, waveguiding vertically through the wafer is difficult. If additional processing is required for waveguides or lenses, it should be compatible with standard VLSI processing. This paper presents one straightforward method of meeting this criterion. Using optical device technology operating at wavelengths beyond the ≈1.1μm Si absorption cutoff, low loss, through-wafer propagation between WSI circuit boards can be achieved over the distances of interest (≈1mm) with the interstitial Si wafers as part of the interconnect "free-space" transmission medium. The thickness of existing VLSI layers can be readily adjusted in featureless regions of the wafer to provide antireflection windows such that the transmittance can be raised to ≈77% for n-type and to ≈97% for p-type silicon. Optical interconnect source-receiver coupling efficiency can be increased and crosstalk decreased using VLSI process compatible apertures and phase reversal zone plate lenses.

Paper Details

Date Published: 19 December 1986
PDF: 6 pages
Proc. SPIE 0679, Current Developments in Optical Engineering and Diffraction Phenomena, (19 December 1986); doi: 10.1117/12.939568
Show Author Affiliations
L A Hornak, AT&T Bell Laboratories (United States)
S K Tewksbury, AT&T Bell Laboratories (United States)
M Hatamian, AT&T Bell Laboratories (United States)
A Ligtenberg, AT&T Bell Laboratories (United States)
B Sugla, AT&T Bell Laboratories (United States)
P Franzon, AT&T Bell Laboratories (United States)

Published in SPIE Proceedings Vol. 0679:
Current Developments in Optical Engineering and Diffraction Phenomena
Robert E. Fischer; James E. Harvey; Warren J. Smith, Editor(s)

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