Method of preparing high glass transition temperature novolak resin for use in high resolution photoresist compositions
CA 2031564 A1 · Owner: Rohm And Haas Company · Inventors: Bogan, Leonard E. Jr.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Novolak resins possessing a high glass transition temperature ("Tg") particularly suited for use in high resolution photoresist compositions are provided. The resins are prepared by the condensation reaction of formaldehyde with a multi-substituted phenol, such as for example 3,5-dimethyl phenol a, resorcinol, and optionally another phenol . Novolak resins having Tg's greater than about 120 degrees Centigrade are preferred. These novolaks are preferably prepared by the condensation reaction of formaldehyde with a multisubstituted phenol, 2-methylresorcinol and m-cresol.
Read the whole patent
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 December 5, 1990. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended December 5, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 5, 2012.
- 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.