Browse Prior Art Database

Line System for Integrated Circuits

IP.com Disclosure Number: IPCOM000082168D
Original Publication Date: 1974-Oct-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Folberth, OG: AUTHOR

Abstract

The most essential characteristics of lines used for signal propagation in digital circuits are attenuation and propagation velocity. As the chip size increases, these parameters gain in significance. Both parameters are influenced by the skin effect, although in different ways.

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Line System for Integrated Circuits

The most essential characteristics of lines used for signal propagation in digital circuits are attenuation and propagation velocity. As the chip size increases, these parameters gain in significance. Both parameters are influenced by the skin effect, although in different ways.

The attenuation increases in the first approximation as the AC resistance Rw increases. Good conductivity and a skin effect that is not fully developed are the prerequisites for a low-attenuation value.

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For standard wafer dopings and clock frequencies, transmission lines on integrated circuit (IC) chips operate in the "slow-wave mode" (see, for example,
H. Hasegawa, M. Furukawa, and H. Yanai, IEEE Transaction Microwave, Vol. MTT-19, No. 11, Nov. 1971, p. 869 ff.). This causes the signal propagation velocity to drop substantially below the velocity of the TEM mode (velocity of light propagation in the respective dielectric medium).

The propagation velocity can be increased by operation in the skin-effect mode. To this end, the silicon underneath the respective line sections is highly doped to ensure a good conductivity. This, in turn, permits the skin effect to develop more effectively so that the propagation velocity of the line increases. The geometry of the metal lines and the conductivity, as well as the geometry of the low-resistivity silicon strips on which the former are superimposed, can be so adapted to each other that the respec...