# US 9,753,076 B2 · Voltage rail monitoring to detect electromigration > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,753,076 B2 - Document ID: US9753076B2 - Status: Granted - Kind: B2 - Application number: 15/008,802 - Filed: 2016-01-28 - Published: 2017-08-03 - Granted: 2017-09-05 - Earliest claimed: 2016-01-28 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: David D. Cadigan; William V. Huott; Adam J. McPadden; Anuwat Saetow; Gary A. Tressler - Web page: https://patentgrep.com/patent/US9753076B2 ## CPC - G01R 31/3008: {Quiescent current [IDDQ] test or leakage current test} - G01R 31/2851: {Testing of integrated circuits [IC] (G01R31/317 takes precedence; testing individual devices G01R31/26; testing printed circuits G01R31/2801)} - G01R 31/2856: {Internal circuit aspects, e.g. built-in test features; Test chips; Measuring material aspects, e.g. electro migration [EM]} - G01R 31/2858: {Measuring of material aspects, e.g. electro-migration [EM], hot carrier injection} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract An integrated circuit is configured to detect current leakage that results from electromigration in the integrated circuit. An isolation power switch selectively connects a target voltage rail in the integrated circuit to a power source. A voltage memory stores a record of an initial voltage decay rate for the target voltage rail while isolated from a manufacturer's power source. A voltage record comparator logic compares the initial voltage decay rate to a field voltage decay rate for the target voltage rail when isolated from a field power source. An output device indicates that a difference between the initial voltage decay rate and the field voltage decay rate for the target voltage rail exceeds a predefined limit, where the difference is a result of current leakage caused by electromigration in the integrated circuit. ## Claims ### Claim 1 An integrated circuit comprising: a target voltage rail, wherein the target voltage rail provides power to at least one circuit node in the integrated circuit; an isolation power switch, wherein the isolation power switch selectively connects the target voltage rail to a power source; a voltage sensor that couples the target voltage rail to a reference voltage source; a memory supervisor coupled to the voltage sensor; a voltage memory coupled to the memory supervisor, wherein the voltage memory stores a record of an initial voltage decay rate for the target voltage rail while isolated from a manufacturer's power source; a clock coupled to the memory supervisor, wherein the clock triggers the memory supervisor to take serial voltage readings from the voltage sensor while the target voltage rail is isolated from a field power source to create a field voltage decay rate for the target voltage rail; a voltage record comparator logic, wherein the voltage record comparator logic compares the initial voltage decay rate to the field voltage decay rate for the target voltage rail; and an output device coupled to the voltage record comparator logic, wherein the output device describes a difference between the initial voltage decay rate and the field voltage decay rate for the target voltage rail that exceeds a predefined limit, and wherein the difference between the initial voltage decay rate and the field voltage decay rate for the target voltage rail is a result of current leakage in the integrated circuit. ### Claim 2 (depends on 1) The integrated circuit of claim 1, wherein the current leakage is a result of electromigration in the integrated circuit. ### Claim 3 (depends on 1) The integrated circuit of claim 1, wherein the initial voltage decay rate was recorded upon a final manufacturing of the integrated circuit. ### Claim 4 (depends on 1) The integrated circuit of claim 1, wherein the initial voltage decay rate was recorded upon a final installation of the integrated circuit into a field replaceable unit (FRU), wherein the FRU is a field replaceable board for an electronic system. ### Claim 5 (depends on 1) The integrated circuit of claim 1, wherein the reference voltage source is a ground. ### Claim 6 (depends on 1) The integrated circuit of claim 1, wherein the reference voltage source is a reference voltage rail. ### Claim 7 (depends on 6) The integrated circuit of claim 6, wherein the reference voltage rail provides a bias voltage to the target voltage rail. ### Claim 8 (depends on 1) The integrated circuit of claim 1, wherein the output device is an input/output connector to a test device. ### Claim 9 (depends on 1) The integrated circuit of claim 1, wherein the output device is an alarm indicator. ### Claim 10 A field replaceable unit (FRU), wherein the FRU is a field replaceable board for an electronic device, and wherein the FRU comprises: an integrated circuit that comprises: a target voltage rail, wherein the target voltage rail provides power to at least one circuit node in the integrated circuit; an isolation power switch, wherein the isolation power switch selectively connects the target voltage rail to a power source; a voltage sensor that couples the target voltage rail to a reference voltage source; a memory supervisor coupled to the voltage sensor; a voltage memory coupled to the memory supervisor, wherein the voltage memory stores a record of an initial voltage decay rate for the target voltage rail while isolated from a manufacturer's power source; a clock coupled to the memory supervisor, wherein the clock triggers the memory supervisor to take serial voltage readings from the voltage sensor while the target voltage rail is isolated from a field power source to create a field voltage decay rate for the target voltage rail; a voltage record comparator logic, wherein the voltage record comparator logic compares the initial voltage decay rate to the field voltage decay rate for the target voltage rail; and an output device coupled to the voltage record comparator logic, wherein the output device indicates that a difference between the initial voltage decay rate and the field voltage decay rate for the target voltage rail exceeds a predefined limit, and wherein the difference between the initial voltage decay rate and the field voltage decay rate for the target voltage rail is a result of current leakage caused by electromigration in the integrated circuit. ### Claim 11 (depends on 10) The FRU of claim 10, wherein the initial voltage decay rate was recorded upon a final manufacturing of the integrated circuit. ### Claim 12 (depends on 10) The FRU of claim 10, wherein the initial voltage decay rate was recorded upon a final installation of the integrated circuit into the FRU. ### Claim 13 (depends on 10) The FRU of claim 10, wherein the reference voltage source is a ground. ### Claim 14 (depends on 10) The FRU of claim 10, wherein the reference voltage source is a reference voltage rail. ### Claim 15 (depends on 14) The FRU of claim 14, wherein the reference voltage rail provides a bias voltage to the target voltage rail. ### Claim 16 (depends on 10) The FRU of claim 10, wherein the output device is an input/output connector to a test device. ### Claim 17 (depends on 10) The FRU of claim 10, wherein the output device is an alarm indicator. ### Claim 18 A computer program product for detecting electromigration in a field replaceable unit, the computer program product comprising a non-transitory computer readable storage medium having program code embodied therewith, the program code readable and executable by a processor to perform a method comprising: quiescenting an integrated circuit that is within a field replaceable unit (FRU), wherein the FRU is a field replaceable board in an electronic device; applying, via an isolation power switch, a test voltage from a field power source to a target voltage rail in the integrated circuit, wherein the test voltage is below an operational voltage for transistors within the integrated circuit; isolating, via the isolation power switch, the target voltage rail from the field power source; measuring, by a voltage sensor coupled to the target voltage rail, a field voltage decay rate for the target voltage rail, wherein the voltage sensor couples the target voltage rail to a reference voltage source; comparing, via a voltage record comparator logic within the integrated circuit, the field voltage decay rate to an initial voltage decay rate for the target voltage rail; and in response to a difference between the field voltage decay rate and the initial voltage decay rate for the target voltage rail exceeding a predetermined limit, sending, via the voltage record comparator logic, a signal to an alarm on the FRU, wherein the difference between the initial voltage decay rate and the field voltage decay rate for the target voltage rail has been predetermined to be a result of current leakage caused by electromigration in the integrated circuit. ### Claim 19 (depends on 18) The computer program product of claim 18, wherein the initial voltage decay rate was recorded upon an installation of the integrated circuit into the field replaceable unit (FRU). ### Claim 20 (depends on 18) The computer program product of claim 18, wherein the reference voltage source is a reference voltage rail that provides a bias voltage to the target voltage rail.