Diagnostic method for detection of multiple defects in a Level Sensitive Scan Design (LSSD)
First Claim
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1. A method of identifying one or more defective shift register latches in a scan chain, the method comprising:
- electrically coupling a plurality of shift register latches into a series configuration so as to form a scan chain circuit, wherein each of the shift register latches includes a first latch and a second latch connected in a master-slave configuration, wherein each of the first latch and second latch includes at least one clock input;
placing the scan chain circuit into an operating region;
loading a scan test pattern into the scan chain circuit;
placing the scan chain circuit into a failing region;
applying a shift clock pulse to the clock input of the second latch, wherein the shift clock pulse is applied while the scan chain circuit is in the failing region;
placing the scan chain circuit into an operating region;
unloading the scan chain circuit; and
identifying at least one defective shift register latch in the scan chain circuit.
1 Assignment
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Accused Products
Abstract
Examiner'"'"'s permission under MPEP §608.01(q) and 37 CFR §1.125(b) is requested to submit a substitute specification and abstract. The substitute specification corrects typographical errors, grammar and formatting. No new matter has been added. The substitute specification and abstract contain no new matter to the specification of record. A marked-up version is attached along with a clean version in an appendix attached hereto.
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Citations
22 Claims
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1. A method of identifying one or more defective shift register latches in a scan chain, the method comprising:
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electrically coupling a plurality of shift register latches into a series configuration so as to form a scan chain circuit, wherein each of the shift register latches includes a first latch and a second latch connected in a master-slave configuration, wherein each of the first latch and second latch includes at least one clock input; placing the scan chain circuit into an operating region; loading a scan test pattern into the scan chain circuit; placing the scan chain circuit into a failing region; applying a shift clock pulse to the clock input of the second latch, wherein the shift clock pulse is applied while the scan chain circuit is in the failing region; placing the scan chain circuit into an operating region; unloading the scan chain circuit; and identifying at least one defective shift register latch in the scan chain circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of identifying one or more defective shift register latches in a scan chain, the method comprising:
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electrically coupling a plurality of shift register latches into a series configuration so as to form a scan chain circuit, wherein each of the shift register latches includes a first latch and a second latch connected in a master-slave configuration, wherein each of the first latch and second latch includes at least one clock input; placing the scan chain circuit into an operating region; loading a scan test pattern into the scan chain circuit; placing the scan chain circuit into a failing region; applying a scan clock pulse to the clock input of the first latch, wherein the scan clock pulse is applied while the scan chain circuit is in the failing region; placing the scan chain circuit into an operating region; applying a shift clock pulse to the clock input of the second latch, wherein the shift clock pulse is applied while the scan chain circuit is in the operating region; unloading the scan chain circuit; and identifying at least one defective shift register latch in the scan chain circuit. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method of identifying one or more defective shift register latches in a scan chain, the method comprising:
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electrically coupling a plurality of shift register latches into a series configuration so as to form a scan chain circuit, wherein each of the shift register latches includes a first latch and a second latch connected in a master-slave configuration, wherein each of the first latch and second latch includes at least one clock input; placing the scan chain circuit into an operating region; loading a scan test pattern into the scan chain circuit; placing the scan chain circuit into a failing region; applying a scan clock pulse to the clock input of the first latch, wherein the scan clock pulse is applied while the scan chain circuit is in the failing region; applying a shift clock pulse to the clock input of the second latch, wherein the shift clock pulse is applied while the scan chain circuit is in the failing region; placing the scan chain circuit into an operating region; unloading the scan circuit; and identifying at least one defective shift register latch in the scan chain circuit. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A computer program product containing programming instructions for identifying one or more defective shift register latches in a scan chain, wherein each of the shift register latches includes a first latch and a second latch connected in a master-slave configuration, wherein each of the first latch and second latch includes at least one clock input, the programming instructions comprising:
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placing the scan chain circuit into an operating region; loading a scan test pattern into the scan chain circuit; placing the scan chain circuit into a failing region; applying a shift clock pulse to the clock input of the second latch, wherein the shift clock pulse is applied while the scan chain circuit is in the operating region placing the scan chain circuit into an operating region; unloading the scan circuit; and identifying at least one defective shift register latch in the scan chain circuit.
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22. A computer program product containing programming instructions for identifying one or more defective shift register latches in a scan chain, wherein each of the shift register latches includes a first latch and a second latch connected in a master-slave configuration, wherein each of the first latch and second latch includes at least one clock input, the programming instructions comprising:
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placing the scan chain circuit into an operating region; loading a scan test pattern into the scan chain circuit; placing the scan chain circuit into a failing region; applying a scan lock pulse to the clock input of the first latch, wherein the scan clock pulse is applied while the scan chain circuit is in the operating region; applying a shift clock pulse to the clock input of the second latch, wherein the shift clock pulse is applied while the scan chain circuit is in the operating region; placing the scan chain circuit into an operating region; unloading the scan circuit; and identifying at least one defective shift register latch in the scan chain circuit.
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Specification