Wafer sensing and clamping monitor
CA 2113290 C · Owner: Stone, Dale Keith · Inventors: Stone, Dale Keith; Holden, Scott Carelton; Tu, Weilin
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A wafer position and clamp sensor. A circuit 114 monitors capacitance between two electrodes 22,24 within a wafer support 14,16,18,20. With no wafer 12 on the support, the capacitance falls in one range with the wafer in place , but, not clamped the capacitance falls in a second range and with the wafer held in, place by an electrostatic attraction the capacitance falls in a third range. The, sensed capacitance is converted to a frequency and then a DC voltage level 164 that can easily be sensed and used to confirm wafer placement and then confirm wafer clamping.
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 January 13, 1994 and granted November 30, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 13, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 13, 2016.
- 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.