Apparatus and methods for semiconductor IC failure detection
First Claim
1. A test structure that is designed for voltage contrast inspection, comprising:
- a first substructure having a plurality of floating conductive structures that are designed to charge to a first potential during a voltage contrast inspection; and
a second substructure that is coupled with a conductive structure having a size selected to cause the second substructure to charge to a second potential that differs from the first potential during the voltage contrast inspection, wherein the first and second substructures are positioned entirely within a single horizontal conductive layer without being electrically coupled with any other horizontal conductive layer.
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Abstract
An improved voltage contrast test structure is disclosed. In general terms, the test structure can be fabricated in a single photolithography step or with a single reticle or mask. The test structure includes substructures which are designed to have a particular voltage potential pattern during a voltage contrast inspection. For example, when an electron beam is scanned across the test structure, an expected pattern of intensities are produced and imaged as a result of the expected voltage potentials of the test structure. However, when there is an unexpected pattern of voltage potentials present during the voltage contrast inspection, this indicates that a defect is present within the test structure. To produce different voltage potentials, a first set of substructures are coupled to a relatively large conductive structure, such as a large conductive pad, so that the first set of substructures charges more slowly than a second set of substructures that are not coupled to the relatively large conductive structure. Mechanisms for fabricating such a test structure are also disclosed. Additionally, searching mechanisms for quickly locating defects within such a test structure, as well as other types of voltage contrast structures, during a voltage contrast inspection are also provided.
91 Citations
10 Claims
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1. A test structure that is designed for voltage contrast inspection, comprising:
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a first substructure having a plurality of floating conductive structures that are designed to charge to a first potential during a voltage contrast inspection; and
a second substructure that is coupled with a conductive structure having a size selected to cause the second substructure to charge to a second potential that differs from the first potential during the voltage contrast inspection, wherein the first and second substructures are positioned entirely within a single horizontal conductive layer without being electrically coupled with any other horizontal conductive layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification