Other

Mentor Graphics Corporation

Nagesh Tamarapalli

Janusz Rajski

Wu-Tung Cheng

Jerzy Tyszer

Yu Jane Huang

Randy Klingenberg

Robert Douglas Thompson

Gang Paul Chen

Manish Sharma

Huaxing Tang

Kun-Han Tsai

Martin Keim

Abu Mokhtarul Hassan

Thomas Hans Rinderknecht

Ronald Press

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.

Enhanced diagnosis with limited failure cycles

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. Likewise, computer-readable media comprising lists of fault candidates identified by any of the disclosed methods or circuit descriptions created or modified by the disclosed methods are provided.

Compactor independent fault diagnosis

Methods, apparatus, and systems for testing, analyzing, and improving integrated circuit yield and quality are disclosed herein. For example, in one exemplary embodiment, one or more fault dictionaries are generated for identifying one or more defect candidates from corresponding observation point combinations. In this exemplary method, the observation point combinations indicate the observation points of a circuit-under-test that captured faulty test values upon application of a respective test pattern. Further, the one or more fault dictionaries in one embodiment are generated by: (a) for a first defect candidate, storing one or more first indicators indicative of test patterns detecting the first defect candidate, and (b) for a second defect candidate, storing at least a second indicator indicative of the test patterns that detect the second defect candidate, the second indicator comprising a bit mask that indicates which of the test patterns detecting the first defect candidate also detect the second defect candidate.

Fault dictionaries for integrated circuit yield and quality analysis methods and systems

A method is disclosed for the automated synthesis of phase shifters&#x2014;circuits used to remove effects of structural dependencies featured by pseudo-random test pattern generators driving parallel scan chains. Using a concept of duality, the method relates the logical states of linear feedback shift registers (LFSRs) and circuits spacing their inputs to each of the output channels. The method generates a phase shifter network balancing the loads of successive stages of LFSRs and satisfying criteria of reduced linear dependency, channel separation and circuit complexity.

Phase shifter with reduced linear dependency

A method is disclosed for the automated synthesis of phase shifters. Phase shifters comprise circuits used to remove effects of structural dependencies featured by pseudo-random test pattern generators driving parallel scan chains. Using a concept of duality, the method relates the logical states of linear feedback shift registers (LFSRs) and circuits spacing their inputs to each of the output channels. The method generates a phase shifter network balancing the loads of successive stages of LFSRs and satisfying criteria of reduced linear dependency, channel separation and circuit complexity.

Methods, apparatus, and systems for computing and analyzing integrated circuit yield and quality are disclosed herein. For example, in one exemplary method disclosed herein information is received from processing test responses of integrated circuits designed for functional use in electronic devices. In this embodiment, the information is indicative of integrated circuit failures observed during testing of the integrated circuits and of possible yield limiting factors causing the integrated circuit failures. Probabilities that one or more of the possible yield limiting factors in the integrated circuits actually caused the integrated circuit failures are determined by statistically analyzing the received information. The probabilities that one or more possible yield limiting factors actually caused the integrated circuit failures are reported. Tangible computer-readable media comprising computer-executable instructions for causing a computer to perform any of the described methods are also disclosed.

Determining and analyzing integrated circuit yield and quality

Exemplary schemes for multi-frequency at-speed logic Built-In Self Test (BIST) are provided. For example, certain schemes allow at-speed testing of very high frequency integrated circuits controlled by a clock signal generated externally or on-chip. Some of the disclosed schemes are also applicable to testing of circuits with multiple clock domains which can be either the same frequency or different frequency. In particular embodiments, the loading and unloading of scan chains is separated from the at-speed testing of the logic between the respective domains and may be done at a faster or slower frequency than the at-speed testing. In certain embodiments, only the capture cycle is performed at the corresponding system timing. In some embodiments, a programmable capture window makes it possible to test every intra- and inter-domain at-speed without the negative impact of clock skew between clock domains.

Method and apparatus for at-speed testing of digital circuits

A scheme for multi-frequency at-speed logic Built-In Self Test (BIST) is provided. This scheme allows at-speed testing of very high frequency integrated circuits controlled by a clock signal generated externally or on-chip. The scheme is also applicable to testing of circuits with multiple clock domains which can be either the same frequency or different frequency. Scanable memory elements of the digital circuit are connected to define plurality of scan chains. The loading and unloading of scan chains is separated from the at-speed testing of the logic between the respective domains and may be done at a faster or slower frequency than the at-speed testing. The BIST controller, Pseudo-Random Pattern Generator (PRPG) and Multi-input Signature Register (MISR) work at slower frequency than the fastest clock domain. After loading of a new test pattern, a clock suppression circuit allows a scan enable signal to propagate for more that one clock cycle before multiple capture clock is applied. This feature relaxes the speed and skew constraints on scan enable signal design. Only the capture cycle is performed at the corresponding system timing. A programmable capture window makes it possible to test every intra- and inter-domain at-speed without the negative impact of clock skew between clock domains.

A built-in-self-test (BIST) circuit is discussed for selecting tristate nets with substantially uniform distribution using a tristate testing control device (TTCD). The circuit allows the deterministic testing of tristate nets in the context of pseudo-random BIST. A feedback shift register is described that activates a single tristate or set of tristate at a time in order to avoid bus contention. Another TTCD embodiment uses a counter and decoder. A test mode switching unit (TMSU) coupled between the TTCD and the tristate net selects test or functional mode for tristate enables. Parallel multiplexers are discussed as one embodiment of a TMSU. Another TMSU embodiment describes even better test coverage. A method, which may be performed on a distributed computer system, is discussed for identifying tristate nets within a net-list and adding a TTCD and a TMSU to the net-list.

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Wilsonville, OR, United States of America

Nagesh Tamarapalli