Electrical mask inspection
First Claim
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1. A method for testing an integrated circuit, comprising the steps of:
- forming a plurality of scan chains, each scan chain formed by the steps of;
forming a first endpoint;
forming a second endpoint;
forming a first metal layer, comprising a plurality of segments;
forming a second metal layer, comprising a plurality of segments;
forming a via layer, comprising a plurality of vias wherein each via is configured and disposed to connect a segment of the first metal layer to a segment of the second metal layer;
wherein the step of forming the first metal layer comprises forming a segment connected to said first endpoint and also comprises forming a segment connected to said second endpoint; and
wherein one of the layers formed is a functional layer, and wherein two of the layers formed are test layers;
performing a resistance measurement between the first endpoint and second endpoint of each of the plurality of scan chains;
indicating a failure if the resistance measurement exceeds a predetermined threshold; and
wherein the step of forming a plurality of scan chains comprises the steps of;
computing the number of scan chains as the number of endpoints divided by two; and
computing the number of vias per scan chain as the total number of vias for a given level divided by the number of chains.
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Abstract
An apparatus and method for electrical mask inspection is disclosed. A scan chain is formed amongst two metal layers and a via layer. One of the three layers is a functional layer under test, and the other two layers are test layers. A resistance measurement of the scan chain is used to determine if a potential defect exists within one of the vias or metal segments comprising the scan chain.
32 Citations
12 Claims
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1. A method for testing an integrated circuit, comprising the steps of:
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forming a plurality of scan chains, each scan chain formed by the steps of; forming a first endpoint; forming a second endpoint; forming a first metal layer, comprising a plurality of segments; forming a second metal layer, comprising a plurality of segments; forming a via layer, comprising a plurality of vias wherein each via is configured and disposed to connect a segment of the first metal layer to a segment of the second metal layer; wherein the step of forming the first metal layer comprises forming a segment connected to said first endpoint and also comprises forming a segment connected to said second endpoint; and wherein one of the layers formed is a functional layer, and wherein two of the layers formed are test layers; performing a resistance measurement between the first endpoint and second endpoint of each of the plurality of scan chains; indicating a failure if the resistance measurement exceeds a predetermined threshold; and wherein the step of forming a plurality of scan chains comprises the steps of; computing the number of scan chains as the number of endpoints divided by two; and computing the number of vias per scan chain as the total number of vias for a given level divided by the number of chains. - View Dependent Claims (3, 4, 5, 6, 7)
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2. A method for testing an integrated circuit, comprising the steps of:
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forming a plurality of scan chains, each scan chain formed by the steps of; forming a first endpoint; forming a second endpoint; forming a first metal layer, comprising a plurality of segments; forming a second metal layer, comprising a plurality of segments; forming a via layer, comprising a plurality of vias wherein each via is configured and disposed to connect a segment of the first metal layer to a segment of the second metal layer; wherein the step of forming the first metal layer comprises forming a segment connected to said first endpoint and also comprises forming a segment connected to said second endpoint; and wherein one of the layers formed is a functional layer, and wherein two of the layers formed are test layers; performing a resistance measurement between the first endpoint and second endpoint of each of the plurality of scan chains; indicating a failure if the resistance measurement exceeds a predetermined threshold; and wherein the step of forming a plurality of scan chains comprises the steps of; computing the number of scan chains as the number of endpoints divided by two; and computing the number of segments per chain as the total number of two-ended segments for a given level divided by the number of chains. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification