Photomask
CA 1212182 A · Owner: Western Electric Company, Incorporated · Inventors: Kuyel, Birol
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A photomask used to form patterns on a resistcoated semiconductor wafer consists of a transparent fused silica baseplate (52) carrying a metallic pattern (54). A plasma deposited SiO2 electrically resistive coating (56) covers the patterned baseplate. Since the coating (56) is electrically resistive it prevents the building up of static charge on the metal (54) sufficient to cause ablation of the pattern by discharge and since the coating (54) has the same refractive index as the baseplate (52) refraction and reflection at the interface between them is prevented.
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
- Granted September 30, 1986. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended September 30, 2003.
- 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.