Improved mask for photolithography
CA 2124077 A1 · Owner: Matthews, James A. · Inventors: Matthews, James A.; Chen, Jang Fung
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An improvement for reducing proximity effects comprised of additional lines, referred to as intensity leveling bars into the mask, pattern. The leveling bars perform the function of adjusting the edge intensity gradients of isolated edges in the mask pattern to match the edge intensity gradients of densely packed edges. Leveling bars are placed parallel to isolated edges such that intensity gradient leveling occurs on all isolated edges of the mask pattern. In addition, the leveling bars are designed to have a width significantly less than the resolution of the exposure tool. Therefore leveling bars that are present in the mask pattern produce resist patterns that completely developed away …
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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 15, 1993. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended January 15, 2013.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 15, 2015.
- 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.