Novolak resins of lowered hydroxyl content and high contrast high thermal stability positive photoresists prepared therefrom
CA 2034602 A1 · Owner: Morton International Inc. · Inventors: Dixit, Sunit S.; Lazarus, Richard M.; Kautz, Randall
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Novolak resins are provided which are the condensation product of (a) a phenol, phenol derivative or mixtures thereof, and (b) a mixture of formaldehyde or a formaldehyde precursor and (1) a monohydroxy aromatic aldehyde and wherein at least a portion of the hydroxyl groups thereof are esterified or (2) a mixture of at least one monohydroxy aromatic aldehyde and at least one non-hydroxylic aromatic aldehyde; the novolak resins having a hydroxyl number of from about 120 to about 180 grams c resin per equivalent of hydroxyl. The novolak resins are especially useful in positive photoresist formulations and have enhanced photospeed and film loss characteristics as well as improved thermal …
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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
- Filed January 18, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended January 18, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 18, 2013.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.