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Expired Canadian patentCanada

Method and composition of matter for improving conductor resolution in microelectronic circuits

CA 1255142 A · Owner: International Business Machines Corporation · Inventors: Fredericks, Edward C.; Via, Giorgio G.

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Abstract From the Canadian patent

A method which provides for a permanent planarization layer on a multilayer integrated circuit. The planarization layer resides above other circuit layers which reflect incident light. A layer of photoresist is formed over the planarization layers and imaged through a mask with circuit defining structure. During exposure of the photoresist incident light passes through the planarization layer. Scattering from the boundary of the planarization layer and photoresist is minimized because the index of refraction of the planarization layer is substantially equal to the index of refraction of the photoresist. Light reflected from the underlying layers is substantially absorbed by the …

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Granted June 6, 1989. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended June 6, 2006.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledOctober 3, 1985
GrantedJune 6, 1989
Term endedJune 6, 2006
Patent numberCA 1255142 A
Classification (IPC)H05K3/06 +2 more

Timeline

Timeline From CIPO dates

1986198919921995199820012004Application filedOct 3, 1985Patent grantedJune 6, 1989Term endedJune 6, 2006

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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.