Method and installation for fast fault localization in an integrated circuit
First Claim
1. A method for location of a fault of the short-circuit type, of a logic gate, known as the defective logic gate, of an integrated circuit, known as the defective circuit, comprising a chip, input terminals and output terminals connected to one another by electrically conductive tracks, and logic gates formed within the chip of the circuit, which is generally in the form of a wafer which defines a main plane of the chip, the tracks extending in the thickness of the chip or on the surface, globally parallel to the main plane, the input and output terminals being connected to the tracks at the periphery of the chip, and at least two electrical energy supply terminals with direct voltage (VDD-VSS), at least one supply terminal of which is connected to a high potential VDD, and at least one supply terminal of which is connected to a low potential VSS, in which:
- a) there is creation and recording of a sequence of distinct vectors, known as location vectors, each of which is formed from a series of signals, which are designed to be able to be applied to the different input terminals of the defective circuit, assuming one of the logic states 0 and 1, and maintaining this logic state throughout an entire period in which it is considered that the location vector is applied to the input terminals, such that this sequence can be applied step by step, one location vector after the other, and keeping each location vector applied for a period which is as long as necessary on the input terminals of the defective circuit and/or of a standard circuit, without the electric state of this circuit changing during this duration;
b) after step a), for at least one location vector applied to the input terminals of the defective circuit and/or of an integrated circuit, known as the standard circuit, which is free from a defective gate and from any fault, and is also identical to the defective circuit, a set of images, known as vector images, is produced and recorded, representing equipotential lines formed by the tracks and the logic gates of the said circuit, each equipotential line corresponding to one of the differentiated states of potential on the vector images, the different vector images of a single set of images being designed to cover and represent the entire surface of the chip, or an entire portion of this surface on which it is being attempted to locate the defective logic gate;
c) after step b), the sequence of location vectors is applied step by step to the input terminals of the defective circuit, and for each location vector, measurement is made of the value IDDQ(j) of the electrical consumption current at rest IDDQ of the defective circuit, which is circulating in at least one of the supply terminals, and it is determined whether this value measured IDDQ(j) is normal or abnormal, and the result of this determination is recorded;
d) after step c), at least one location vector, known as the abnormal location vector, is applied to the input terminals of the defective circuit and/or of a standard circuit, for which the fact has previously been determined and recorded that the value measured IDDQ(j) of the electrical consumption current at rest IDDQ of the defective circuit is abnormal, and a set of images, known as abnormal vector images, of the said circuit with this abnormal location vector is produced and recorded; and
e) after step d), in a further step of location of the defective gate, at least one comparison is made between at least one abnormal vector image and another pre-recorded image, known as the reference image, corresponding to the same portion of surface of the chip of the defective circuit or of the standard circuit as the abnormal vector image, these images being selected such that this comparison makes it possible to select an area, known as the defective area, of the surface of the chip on which there can be located an equipotential input line of the defective logic gate and/or an equipotential output line of the defective logic gate, and/or the defective logic gate.
2 Assignments
0 Petitions
Accused Products
Abstract
The invention relates to a method and an installation for fast location of a fault in an integrated circuit. A sequence of NRZ location vectors is created, the abnormal location vectors are determined, for which the value of the electrical consumption current at rest IDDQ of the circuit is abnormal, at least one set of images is produced with an abnormal location vector, and at least one abnormal vector image is compared with a reference image.
11 Citations
35 Claims
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1. A method for location of a fault of the short-circuit type, of a logic gate, known as the defective logic gate, of an integrated circuit, known as the defective circuit, comprising a chip, input terminals and output terminals connected to one another by electrically conductive tracks, and logic gates formed within the chip of the circuit, which is generally in the form of a wafer which defines a main plane of the chip, the tracks extending in the thickness of the chip or on the surface, globally parallel to the main plane, the input and output terminals being connected to the tracks at the periphery of the chip, and at least two electrical energy supply terminals with direct voltage (VDD-VSS), at least one supply terminal of which is connected to a high potential VDD, and at least one supply terminal of which is connected to a low potential VSS, in which:
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a) there is creation and recording of a sequence of distinct vectors, known as location vectors, each of which is formed from a series of signals, which are designed to be able to be applied to the different input terminals of the defective circuit, assuming one of the logic states 0 and 1, and maintaining this logic state throughout an entire period in which it is considered that the location vector is applied to the input terminals, such that this sequence can be applied step by step, one location vector after the other, and keeping each location vector applied for a period which is as long as necessary on the input terminals of the defective circuit and/or of a standard circuit, without the electric state of this circuit changing during this duration; b) after step a), for at least one location vector applied to the input terminals of the defective circuit and/or of an integrated circuit, known as the standard circuit, which is free from a defective gate and from any fault, and is also identical to the defective circuit, a set of images, known as vector images, is produced and recorded, representing equipotential lines formed by the tracks and the logic gates of the said circuit, each equipotential line corresponding to one of the differentiated states of potential on the vector images, the different vector images of a single set of images being designed to cover and represent the entire surface of the chip, or an entire portion of this surface on which it is being attempted to locate the defective logic gate; c) after step b), the sequence of location vectors is applied step by step to the input terminals of the defective circuit, and for each location vector, measurement is made of the value IDDQ(j) of the electrical consumption current at rest IDDQ of the defective circuit, which is circulating in at least one of the supply terminals, and it is determined whether this value measured IDDQ(j) is normal or abnormal, and the result of this determination is recorded; d) after step c), at least one location vector, known as the abnormal location vector, is applied to the input terminals of the defective circuit and/or of a standard circuit, for which the fact has previously been determined and recorded that the value measured IDDQ(j) of the electrical consumption current at rest IDDQ of the defective circuit is abnormal, and a set of images, known as abnormal vector images, of the said circuit with this abnormal location vector is produced and recorded; and e) after step d), in a further step of location of the defective gate, at least one comparison is made between at least one abnormal vector image and another pre-recorded image, known as the reference image, corresponding to the same portion of surface of the chip of the defective circuit or of the standard circuit as the abnormal vector image, these images being selected such that this comparison makes it possible to select an area, known as the defective area, of the surface of the chip on which there can be located an equipotential input line of the defective logic gate and/or an equipotential output line of the defective logic gate, and/or the defective logic gate. - 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, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A system for location of a fault of the short-circuit type, in a logic gate, known as the defective logic gate, of an integrated circuit, known as the defective circuit, comprising a chip for the input terminals and output terminals, which are connected to one another by electrically conductive tracks and logic gates formed within the chip of the circuit, which is generally in the form of a wafer defining a main plane of the chip, the tracks extending in the thickness of the chip or on the surface, globally parallel to the main plane, the input and output terminals being connected to the tracks at the periphery of the chip, and at least two electrical energy supply terminals with direct voltage (VDD-VSS), at least one supply terminal of which is connected to a high potential VDD, and at least one supply terminal of which is connected to a low potential VSS, the said installation comprising:
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means for creating and recording a sequence of distinct vectors, known as location vectors, each of which is formed from a series of binary signals, which are designed to be able to be applied to the different input terminals of the defective circuit, assuming one of the logic states 0 and 1, and maintaining this logic state throughout an entire period, in which it is considered that the location vector is applied to the input terminals; equipotential imagery means, which, for at least one location vector applied to the input terminals of the defective circuit and/or of an integrated circuit, known as the standard circuit, which is free from a defective gate and from any fault, and is also identical to the defective circuit, can produce and record a set of images, known as vector images, representing equipotential lines formed by tracks and the logic gates of the said circuit, each equipotential line corresponding to one of the differentiated states of potential on the vector images, the different vector images of a single set of images being designed to cover and represent the entire surface of the chip, or an entire portion of this surface on which it is being attempted to locate the defective logic gate, means for applying the sequence of location vectors step by step to the input terminals of the defective circuit; for each location vector, means for measurement of the value IDDQ(j) of the electrical consumption current at rest IDDQ of the defective circuit, which is circulating in at least one of the supply terminals; means for calculation which can determine whether this value measured IDDQ(j) is normal or abnormal, and can record the result of this determination; and means for calculation, which can make at least one comparison between at least one abnormal vector image and another pre-recorded image, known as the reference image, corresponding to the same portion of surface of the chip of the defective circuit or of the standard circuit as the abnormal vector image, these images being selected such that this comparison makes it possible to select an area, known as the defective area, of the surface of the chip on which there can be located an equipotential input line of the defective logic gate and/or an equipotential line of the defective logic gate, and/or the defective logic gate. - View Dependent Claims (34, 35)
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Specification