Integrated circuit electromigration monitor
First Claim
1. A method of making an integrated circuit including the step of determining the electromigration characteristics of an integrated circuit conductor by steps comprising flowing an electrical current through a test structure, and determining the time for a failure to occur,characterized in that the current density of said electrical current is at least 5×
- 106 amps/cm2, and said test structure comprises an elongated test conductor at least 50 micrometers long, wherein said elongated test conductor is contacted at its ends by wider metal conductors having a width at least 5 times the width of said elongated test conductor, and with said wider metal conductors tapering down to the width of said test conductor.
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Abstract
The electromigration characteristics of integrated circuit conductors are determined by passing a high current for a short period of time through an inventive test structure. This provides a rapid test in a more accurate manner than with the prior art SWEAT (Standard Wafer-level Electromigration Accelerated Test) structure. The test results have been found to be well correlated with long-term low current electromigration tests. A sensitive differential test may be implemented that determines the effects of topography features. The inventive test technique can be performed on every wafer lot, or even every wafer, so that adjustments to the wafer fabrication process can be rapidly implemented.
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Citations
28 Claims
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1. A method of making an integrated circuit including the step of determining the electromigration characteristics of an integrated circuit conductor by steps comprising flowing an electrical current through a test structure, and determining the time for a failure to occur,
characterized in that the current density of said electrical current is at least 5× - 106 amps/cm2, and said test structure comprises an elongated test conductor at least 50 micrometers long, wherein said elongated test conductor is contacted at its ends by wider metal conductors having a width at least 5 times the width of said elongated test conductor, and with said wider metal conductors tapering down to the width of said test conductor.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of making an integrated circuit including the step of determining the electromigration characteristics of an integrated circuit conductor,
characterized by steps comprising flowing electrical current through first and second test structures, and comparing the effect of the current flow on the structures, wherein said first test structure comprises elongated topographic features located under, and oriented generally transverse to, said test conductor, and said second test structure is located on a generally planar surface, and further characterized in that each of said test structures comprise elongated test conductors at least 50 micrometers long, wherein said elongated test conductors are contacted at their ends by wider metal conductors having a width at least 5 times the width of said elongated test conductors, and with said wider metal conductors tapering down to the width of said test conductors.
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22. A method of making an integrated circuit including the step of determining the electromigration characteristics of an integrated circuit conductor,
characterized by steps comprising flowing electrical current through an elongated test conductor at least 50 micrometers long, wherein said elongated test conductor is contacted at both ends by wider metal conductors having a width at least 5 times the width of said elongated test conductor, and with said wider metal conductors tapering down to the width of said test conductor.
Specification