Method for making surveillance devices with multiple capacitors
First Claim
1. A method for making a surveillance and/or identification device, comprising:
- a) forming an electrically conducting strap and a lower capacitor electrode on a substrate;
b) forming a first dielectric film on the substrate and on a portion of the strap, the first dielectric film exposing a portion of the strap and having an opening over a portion of the lower capacitor electrode;
c) forming a capacitor dielectric film in the opening, the capacitor dielectric film having a significantly smaller thickness than the first dielectric film;
d) forming an upper capacitor electrode on the first dielectric film and the capacitor dielectric film, such that the upper capacitor electrode (i) is capacitively coupled to the lower capacitor electrode and (ii) forms a first capacitor and a second capacitor connected in parallel, wherein the first capacitor includes the relatively thin capacitor dielectric film and the second capacitor includes the relatively thick dielectric film and the second capacitor has a greater capacitance than the first capacitor; and
e) forming an antenna and/or inductor on the upper capacitor electrode and the strap, or attaching an antenna and/or inductor to the upper capacitor electrode and the strap.
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Abstract
The present invention relates to surveillance and/or identification devices having capacitors connected in parallel or in series, and methods of making and using such devices. Devices with capacitors connected in parallel, where one capacitor is fabricated with a relatively thick capacitor dielectric and another is fabricated with a relatively thin capacitor dielectric achieve both a high-precision capacitance and a low breakdown voltage for relatively easy surveillance tag deactivation. Devices with capacitors connected in series result in increased lateral dimensions of a small capacitor. This makes the capacitor easier to fabricate using techniques that may have relatively limited resolution capabilities.
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Citations
24 Claims
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1. A method for making a surveillance and/or identification device, comprising:
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a) forming an electrically conducting strap and a lower capacitor electrode on a substrate; b) forming a first dielectric film on the substrate and on a portion of the strap, the first dielectric film exposing a portion of the strap and having an opening over a portion of the lower capacitor electrode; c) forming a capacitor dielectric film in the opening, the capacitor dielectric film having a significantly smaller thickness than the first dielectric film; d) forming an upper capacitor electrode on the first dielectric film and the capacitor dielectric film, such that the upper capacitor electrode (i) is capacitively coupled to the lower capacitor electrode and (ii) forms a first capacitor and a second capacitor connected in parallel, wherein the first capacitor includes the relatively thin capacitor dielectric film and the second capacitor includes the relatively thick dielectric film and the second capacitor has a greater capacitance than the first capacitor; and e) forming an antenna and/or inductor on the upper capacitor electrode and the strap, or attaching an antenna and/or inductor to the upper capacitor electrode and the strap. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification