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Expired Canadian patentCanada

Method of depositing silicon films with reduced structural defects

CA 1256754 A · Owner: Unisys Corporation · Inventors: Wonsowicz, Casimir J.; Canfield, Glenn R.

CIPO record

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Abstract From the Canadian patent

Silicon films in integrated circuits are mass produced with reduced structural defects by passing a reactant gas which contains silicon over a batch of wafers in a quartz chamber to deposit a silicon substance on both the wafers in a quartz chamber and the quartz walls of the chamber; repeating the passing step on other batches of wafers until the thickness of the silicon substance on the quartz walls exceeds a predetermined limit; directing a forceful stream of gas against the quartz walls to knock microscopic particles of the silicon substance therefrom; removing the knocked-off microscopic particles from the chamber; and continuing the passing and repeating steps with no intervening acid …

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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 July 4, 1989. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended July 4, 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.
FiledJuly 29, 1985
GrantedJuly 4, 1989
Term endedJuly 4, 2006
Patent numberCA 1256754 A
Classification (IPC)C23C16/44

Timeline

Timeline From CIPO dates

1986198919921995199820012004Application filedJuly 29, 1985Patent grantedJuly 4, 1989Term endedJuly 4, 2006

Sources & verification

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