Active solid-state devices (e.g. – transistors – solid-state diode – Test or calibration structure
Reexamination Certificate
2001-03-26
2004-11-16
Zarabian, Amir (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Test or calibration structure
C257S679000
Reexamination Certificate
active
06818920
ABSTRACT:
The invention relates to an integrated circuit provided with a substrate and with a memory having a first programmable memory element, which memory element
comprises an electrically conducting organic material,
has a non-programmed and a programmed state, and
comprises a first electrode and a second electrode.
The invention also relates to a transponder comprising an integrated circuit, and an antenna. The invention further relates to a security paper comprising an integrated circuit.
The invention further relates to a method of programming a memory in an integrated circuit, which memory comprises a first programmable memory element, which memory element comprises an electrically conducting organic material, has a non-programmed and a programmed state, and comprises a first electrode and a second electrode.
Such an integrated circuit is known from WO-A-99/30432. The known circuit has a 15-bit memory. The memory comprises a code generator provided with 15 programmable paths. The memory is programmed in that a vertical interconnect area, a “via”, is locally provided between two electrically conducting layers. The via is mechanically created in that the layers are compressed with the point of a needle, i.e. the vertical interconnect area is notched by means of a tool tip. Part of the integrated circuit is short-circuited thereby. The result is that a bit with value “0” is given a value “1” or vice versa. An integrated circuit is also referred to as an “IC” hereinafter. The circuit is used in a transponder which comprises besides the IC an antenna and a first connection between the IC and the antenna.
It is a disadvantage of the known IC that programming takes place mechanically. This method of programming requires special equipment, because a via is to be created locally by means of pressure. This method is liable to defects because of the positioning of the first memory element with respect to the equipment. Furthermore, programming of the memory is difficult to perform after the manufacture of the IC; it is necessary for the flexible IC to be mounted on a rigid support if the pressure is to be applied. Such a fastening is present during manufacture, but not afterwards.
It is a first object of the invention to provide an integrated circuit of the kind described in the opening paragraph which can be programmed in a simple manner.
It are second and third objects of the invention to provide a transponder and a security paper of the kind described in the preamble whose integrated circuit can be easily programmed after its manufacture has been completed.
It is a fourth object of the invention to provide a method of the kind described in the preamble by means of which the memory of the integrated circuit can be programmed also after the manufacture of the memory has been completed.
The first object is achieved in that
the first and the second electrode are interconnected in the non-programmed state by an electrically conducting bridge which comprises the organic material,
said bridge is at least partly interrupted in the programmed state, and
the first memory element is programmable through heating of the organic material.
The result of programming of the IC according to the invention is inter alia a reduction in the conduction through the first memory element, so that electrical reading of the first memory element detects a transition from “1” to “0”. The reduction in conduction is caused by the at least partial interruption of the bridge. That is to say, a cross-section through the bridge transverse to the longitudinal direction of the bridge will be smaller after programming than it was originally. Alternatively, the bridge may be fully interrupted. The temperature in the bridge will have risen to at least a transition temperature of the organic material during the interruption process.
It is an advantage of the IC according to the invention that it can be programmed much more quickly than the known IC. The first memory element can be programmed in a few microseconds. Even supposing that a few hundreds of memory elements are to be programmed in succession, the IC can still be programmed in one to only a few seconds.
The energy required for heating may be supplied optically and electrically. Preferably, the first memory element is programmed electrically. The inventors have in fact found that electrically conducting organic materials after doping have the property that their resistivity rises with temperature. Examples of such organic materials, which are preferably built up from repetitive units, are: pentacene, polyaniline, polythiophene, poly(3-4-dialkyl-2,2′-bithiophene), polypyrrole, poly(p-phenylenesulfide), polythienylene-vinylene, polyfuranylene-vinylene, polyDOT, and copolymers of the monomers of the above. Substituted variants of these materials, for example with alkyl, alkoxy, alkylalkoxy, or cyclic groups, may also be used.
In an embodiment of the IC according to the invention, a first transistor is present which during programming provides a voltage across the first memory element so as to heat the first memory element. The first transistor may be connected as a diode here. The first transistor is preferably connected in series with the first memory element, which series arrangement is present between a first bit line and a first word line. The first bit line and the first word line are both electrical conductor tracks which form part of respective patterned layers. Any further bit lines, word lines, and other lines which may be present, such as one or several supply lines, are also electrical conductor tracks which form part of patterned layers. The first transistor is important for selectively programming the first memory element. If the memory is a matrix of word and bit lines with interposed series circuits, the memory elements should be programmable independently of one another. The first transistor provides the first memory element with an input and an output, such that a current can flow in one direction only. While the first memory element is being programmed, no current circuit with a further series arrangement of a further memory element at a further transistor is possible between the first bit line and the first word line. The first memory element is thus independently programmable.
During electrical programming of the first memory element, heating of the bridge takes place by means of heat dissipated by passage of current through the first memory element. If the electrical programming is to take place efficiently, the heat dissipated in the bridge should not be capable of flowing away to any appreciable extent. One or several of the following measures may be taken for limiting the removal of heat from the bridge.
A first measure is that an electrical conductor track is present, perpendicular projections of said conductor track and of the bridge on the substrate overlapping each other. A perpendicular projection of the electrical conductor track on the substrate has an overlap with a perpendicular projection of the bridge on the substrate. This conductor track dissipates heat when a current is passed through it, as does any conductor track. In this manner, the conductor track ensures a heating-up of portions of the IC around the bridge. The temperature difference between the bridge and the surrounding portions is reduced, with the result that there will be a reduced heat transfer from the bridge to the surrounding portions.
A second measure is that the first memory element has a spiraling or meandering shape. There will be a smaller distance between a first and a second point of the element in perpendicular direction than longitudinally along the element in a spiraling or meandering element. The possibility of heat dissipation from the first point is smaller in the spiraling or meandering element than in an elongate element, because heat will be dissipated also at the adjacent second point in the first layer. As a result, the temperature in the spiraling or meandering element will rise more quickly during programming. Programming thus proceeds more eff
De Leeuw Dagobert Michel
Gelinck Gerwin Hermanus
Hart Cornelis Maria
Koninklijke Philips Electronics , N.V.
Rose Kiesha
Simons Kevin
Zarabian Amir
LandOfFree
Integrated circuit provided with a substrate and memory... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Integrated circuit provided with a substrate and memory..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Integrated circuit provided with a substrate and memory... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3343787