Circuit to detect previous use of computer chips using passive test wires
AssigneeInternational Business Machines Corporation
InventorsKeith A. Jenkins, Barry P. Linder, Kevin G. Stawiasz
Life of this patent
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Abstract
A test structure and method to detect open circuits due to electromigration or burn-out in test wires and inter-level vias. Electromigration occurs when current flows through circuit wires leading to a circuit interruption within the wire. The test structure is a passive test wire arranged in one of several configurations within the circuit of a computer chip. The dimensions and resistances of test wires can vary according to the test structure configuration. Each test wire is measured for an electrical discontinuity after the computer chip is powered-on. If a wiring interruption is detected, it is concluded that the chip had been powered-on before.
Claims8
A method for detecting previous use of a computer chip, the method comprising the steps of:
- applying a voltage to an array of passive test wires extending between a voltage source and a ground to form a circuit integrated into the computer chip, wherein each passive test wire of the array of test wires is of a different length, width, or thickness, such that each of the passive test wires remains continuous for a different amount of time upon an application of power;
- measuring the electrical discontinuity of each of the passive test wires to detect previous use of the computer chip;
- and
- wherein each of the passive test wires is configured to be activated only by applying power to the computer chip for a specified amount of time, such that the electrical discontinuity occurs only if the computer chip was used for the specified amount of time;
- the array of passive test wires is coupled to a logic circuit;
- and
- the logic circuit is arranged to determine a length of time the computer chip was previously in use based on the current flowing through each of the passive test wires.
Dependencies are inferred from the claim text.