Abstract: Disclosed are representative embodiments of methods, apparatus, and systems for partitioning-based Test Access Mechanisms (TAM). Test response data are captured by scan cells of a plurality scan chains in a circuit under test and are compared with test response data expected for a good CUT to generate check values. Based on the check values, partition pass/fail signals are generated by partitioning scheme generators. Each of the partitioning scheme generators is configured to generate one of the partition pass/fail signals for one of partitioning schemes. A partitioning scheme divides the scan cells into a set of non-overlapping partitions. Based on the partition pass/fail signals, a failure diagnosis process may be performed.

Abstract: Scan chain diagnosis techniques are disclosed. Faulty scan chains are modeled and scan patterns are masked to filter out loading-caused failures. By simulating the masked scan patterns, failing probabilities are determined for cells on a faulty scan chain. One or more defective cells are identified based upon the failing probability information. A noise filtering system such as the one based upon adaptive feedback may be adopted for the identification process.

Abstract: Aspects of the invention relate to yield analysis techniques for generating root cause candidates for yield analysis. With various implementations of the invention, points of interest are first identified in a layout design. Next, regions of interest are determined for the identified points of interest. Next, one or more properties are extracted from the regions of interest. Based at least on the one or more properties, diagnosis reports of failing devices fabricated according to the layout design are analyzed to identify probable root causes.

Abstract: Embodiments of the disclosed technology comprise techniques that can be used to generate scan chain test patterns and improve scan chain failure diagnosis resolution. For example, certain embodiments can be used to generate high quality chain diagnosis test patterns that are able to isolate a scan chain defect to a single scan cell. At least some embodiments can be used to locate faults over multiple capture cycles in the scan chain.

Abstract: A dictionary-based scan chain fault detector includes a dictionary with fault signatures computed for scan cells in the scan chain. Entries in the fault dictionary are compared with failures in the failure log to identify a faulty scan cell. In one embodiment a single fault in a scan chain is identified. In another embodiment, a last fault and a first fault in a scan chain are identified.

Abstract: Disclosed are representative embodiments of methods, apparatus, and systems for partitioning-based Test Access Mechanisms (TAM). Test response data are captured by scan cells of a plurality scan chains in a circuit under test and are compared with test response data expected for a good CUT to generate check values. Based on the check values, partition pass/fail signals are generated by partitioning scheme generators. Each of the partitioning scheme generators is configured to generate one of the partition pass/fail signals for one of partitioning schemes. A partitioning scheme divides the scan cells into a set of non-overlapping partitions. Based on the partition pass/fail signals, a failure diagnosis process may be performed.

Abstract: Chain or logic diagnosis resolution can be enhanced in the presence of limited failure cycles using embodiments of the various methods, systems, and apparatus described herein. For example, pattern sets can be ordered according to a diagnosis coverage figure, which can be used to measure chain or logic diagnosability of the pattern set. Per-pin based diagnosis techniques can also be used to analyze limited failure data.

Abstract: Chain or logic diagnosis resolution can be enhanced in the presence of limited failure cycles using embodiments of the various methods, systems, and apparatus described herein. For example, pattern sets can be ordered according to a diagnosis coverage figure, which can be used to measure chain or logic diagnosability of the pattern set. Per-pin based diagnosis techniques can also be used to analyze limited failure data.

Abstract: Methods of diagnostic test pattern generation for small delay defects are based on identification and activation of long paths passing through diagnosis suspects. The long paths are determined according to some criteria such as path delay values calculated with SDF (Standard Delay Format) timing information and the number of logic gates on a path. In some embodiments of the invention, the long paths are the longest paths passing through a diagnosis suspect and reaching a corresponding failing observation point selected from the failure log, and N longest paths are identified for each of such pairs.

Abstract: Speed-path debug techniques based on at-speed scan test patterns. Potential speed paths are identified based upon detected at-speed scan pattern failures and unknown X-value simulation. When the number of identified speed paths is large, the suspect speed paths are ranked.

Abstract: Techniques are disclosed for reducing the set of initial candidates in signature based diagnosis methodology. These techniques are based on a unique way of making optimum use of information from logic back-cone tracing along with equations that describe the test response compactor.

Abstract: Chain or logic diagnosis resolution can be enhanced in the presence of limited failure cycles using embodiments of the various methods, systems, and apparatus described herein. For example, pattern sets can be ordered according to a diagnosis coverage figure, which can be used to measure chain or logic diagnosability of the pattern set. Per-pin based diagnosis techniques can also be used to analyze limited failure data.

Abstract: Embodiments of the disclosed technology comprise techniques that can be used to generate scan chain test patterns and improve scan chain failure diagnosis resolution. For example, certain embodiments can be used to generate high quality chain diagnosis test patterns that are able to isolate a scan chain defect to a single scan cell. At least some embodiments can be used to locate faults over multiple capture cycles in the scan chain.

Abstract: Methods, apparatus, and systems for performing fault diagnosis are disclosed herein. In certain disclosed embodiments, methods for diagnosing faults from compressed test responses are provided. For example, in one exemplary embodiment, a circuit description of an at least partially scan-based circuit-under-test and a compactor for compacting test responses captured in the circuit-under-test is received. A transformation function performed by the compactor to the test responses captured in the circuit-under-test is determined. A diagnostic procedure for evaluating uncompressed test responses is modified into a modified diagnostic procedure that incorporates the transformation function therein. Computer-readable media comprising computer-executable instructions for causing a computer to perform any of the disclosed methods are also provided.

Abstract: Methods, apparatus, and systems for performing fault diagnosis are disclosed herein. In one exemplary embodiment, a failure log is received comprising entries indicative of compressed test responses to chain patterns and compressed test responses to scan patterns. A faulty scan chain in the circuit-under-test is identified based at least in part on one or more of the entries indicative of the compressed test responses to chain patterns. One or more faulty scan cell candidates in the faulty scan chain are identified based at least in part on one or more of the entries indicative of the compressed test responses to scan patterns. The one or more identified scan cell candidates can be reported. Computer-readable media comprising computer-executable instructions for causing a computer to perform any of the disclosed methods are also provided. Likewise, computer-readable media storing lists of fault candidates identified by any of the disclosed methods are also provided.

Abstract: In embodiments of the disclosed technology, diagnosis of a circuit is performed using compactor signatures (a technique referred to herein as “signature-based diagnosis”). Signature-based diagnosis typically does not require a test step that bypasses the compactor. Compactor signatures can be read from a compactor on a per-pattern basis, and an expected signature can be loaded into a compactor while an actual signature is being read from the compactor. Error functions can be used to describe relationships between errors in scan cell values and per-pattern compactor signatures, and the functions can be used to help generate a list of fault candidates in a circuit design.

Abstract: Aspects of the invention relate to techniques of using two-dimensional scan architecture for testing and diagnosis. A two-dimensional scan cell network may be constructed by coupling input for each scan cell to outputs for two or more other scan cells and/or primary inputs through a multiplexer. To test and diagnose the two-dimensional scan cell network, the two-dimensional scan cell network may be loaded with chain patterns and unloaded with corresponding chain test data along two or more sets of scan paths. Based on the chain test data, one or more defective scan cells or defective scan cell candidates may be determined.

Abstract: Embodiments of the disclosed technology comprise software-based techniques that can be used to improve scan chain test pattern generation and scan chain failure diagnosis resolution. For example, certain embodiments can be used to generate high quality chain diagnosis test patterns that are able to isolate a scan chain defect to a single scan cell. Such embodiments can be used to generate a “complete” test set—that is, a set of chain diagnosis test patterns that is able to isolate any scan chain defect in a faulty scan chain to a single scan cell.

Abstract: Embodiments of the disclosed technology comprise software-based techniques that can be used to improve scan chain test pattern generation and scan chain failure diagnosis resolution. For example, certain embodiments can be used to generate high quality chain diagnosis test patterns that are able to isolate a scan chain defect to a single scan cell. Such embodiments can be used to generate a “complete” test set—that is, a set of chain diagnosis test patterns that is able to isolate any scan chain defect in a faulty scan chain to a single scan cell.

Abstract: Aspects of the invention relate to techniques for diagnosing compound hold-time faults. A profiling-based scan chain diagnosis may be performed on a faulty scan chain to determine observed scan cell failing probability information and one or more faulty segments based on scan pattern test information. Calculated scan cell failing probability information may then be derived. Based on the calculated scan cell failing probability information and the observed scan cell failing probability information, one or more validated faulty segments are verified to have one or more compound hold-time faults. Finally, one or more clock defect suspects may be identified based on information of the one or more validated faulty segments.