Synopsys, Inc.

Rohit Kapur

Thomas W Williams

Suryanarayana Duggirala

Jyotirmoy Saikia

Emil I Gizdarski

Frederic J Neuveux

Parthajit Bhattacharya

Nodari Sitchinava

Samitha Samaranayake

Subramanian Chebiyam

Anshuman Chandra

Santosh Shripad Kulkarni

Peter Wohl

John A Waicukauski

Rajesh Uppuluri

Neeraj Surana

Salvatore Talluto

Cyrus Hay

Pramod Notiyath

Tammy Fernandes

Ashok Anbalan

Subhadip Kundu

Alodeep Sanyal

Chandramouli Gopalakrishnan

Girish A Patankar

Tom W Williams

Denis Martin

Ramakrishnan Balasubramanian

Yasunari Kanzawa

Tony Taylor

Mallika Kapur

Maya Kapur

Ashwin Kumar

Sunil Reddy Tiyyagura

Sushovan Podder

Sanjay Ramnath

Methods and apparatuses to assign faults to nets in an integrated circuit (IC) are described. Each net comprises a drive pin, a set of load pins, and a fan-out structure that electrically couples the drive pin to the set of load pins. During operation, a fan-out structure of a net can be partitioned into a set of non-overlapping subnets and a set of branch nodes, wherein each branch node electrically couples three or more non-overlapping subnets. Next, each branch node can be represented by using a subnet primitive, wherein each subnet primitive comprises three or more pins that are electrically coupled to non-overlapping subnets that are electrically coupled by the branch node. A fault can then be assigned to a pin of a subnet primitive that is electrically coupled to a non-overlapping subnet, thereby modeling the fault in the non-overlapping subnet.

Layout-aware test pattern generation and fault detection

An automated visualization tool in a command line environment allows complex log data to be represented by symbols and associated information for clarity of communication and better understanding of the associated design.

Automatically generated schematics and visualization

Information is received describing test response signals generated by scan cells of an integrated circuit and physical shift failures representing mismatches between the test response signals and expected test response signals of the integrated circuit. The test response signals are mapped to a subset of the scan cells associated with the physical shift failures. Fault simulation is performed for the mapped subset of the scan cells to identify physical faults located within the integrated circuit causing the physical shift failures.

Mapping physical shift failures to scan cells for detecting physical faults in integrated circuits

A method and apparatus of a novel command coverage analyzer is disclosed. Combinations of commands, options, arguments, and values of a product are extracted, customer environment and uses are considered, and a more comprehensive and accurate quality of software process and metric is provided.

Command coverage analyzer

Methods and apparatuses to generate test patterns for detecting faults in an integrated circuit (IC) are described. During operation, the system receives a netlist and a layout for the IC. The system then generates a set of faults associated with the netlist to model a set of defects associated with the IC. Next, the system determines a set of likelihoods of occurrence for the set of faults based at least on a portion of the layout associated with each fault in the set of faults. The system subsequently generates a set of test patterns to target the set of faults, wherein the set of test patterns are generated based at least on the set of likelihoods of occurrence associated with the set of faults.

A method for masking scan chains in a test circuit of an integrated circuit is disclosed. A test pattern to be fed into the test circuit of the integrated circuit is generated. The generated test pattern can be used for detecting a primary fault, one or more secondary faults, and one or more tertiary faults. A mask to mask the output of the scan chains of the test circuit is generated. If a condition is not met, a mask that increases the total number of detectable faults is generated. If the condition is met, a mask that protects the primary fault of the test pattern is generated.

Scheme for masking output of scan chains in test circuit

A method for masking scan chains in a test circuit of an integrated circuit is disclosed. The test circuit includes multiple mask banks. Different mask patterns are stored in each of the mask banks. A first mask bank of the multiple mask banks is selected and the mask pattern stored in the selected first mask bank is used for masking the output of the scan chains of the test circuit during a first portion of a test cycle. A second mask bank of the multiple mask banks is selected and the ask pattern stored in the selected second mask bank is used for masking the output of the scan chains of the test circuit during a second portion of the test cycle.

Handling of undesirable distribution of unknown values in testing of circuit using automated test equipment

A disclosed configuration is for identifying at least one failure indicating scan test cell of a circuit-under-test, CUT, the CUT having a plurality of scan test cells, is provided. The configuration comprises generating a plurality of error signatures by means of a compactor of the CUT, wherein each of the error signatures of the plurality of error signatures consist of a respective sequence of bits comprising at least one failure indicating bit, assigning each error signature to at least a first, a second and a third signature type according to a total number of failure indicating bits of the respective error signature and mapping at least a predefined minimum number of error signatures to respective scan test cells of the plurality of scan test cells. For each error signature, a priority of the mapping is determined by the signature type the respective error signature has been assigned to.

Identifying failure indicating scan test cells of a circuit-under-test

Operating a scan chain of a test circuit of an integrated circuit to have either a single fanout or multiple fanout to a compressor. The test circuit receives a fanout control signal for configuring the fanout of the scan chain. If the fanout control signal indicates configuring of the scan chain with a single fanout, the output of the scan chain is sent to one input of a compressor. If the fanout control signal indicates configuring of the scan chain with multiple fanout, the output of the scan chain is sent to multiple inputs of the compressor.

A method for reordering a test pattern set for testing an integrated circuit is disclosed. A productivity index is computed for each test pattern in a test pattern set. The productivity index of a first test pattern and the productivity index of a second test pattern are compared. If the productivity index of the second test pattern is larger than the productivity index of the first test pattern, the location of the first test pattern and the second test pattern are swapped.

Reordering or removal of test patterns for detecting faults in integrated circuit

A method for localizing at least one scan flop associated with a fault in an integrated circuit. A first test pattern, including a first scan-in data and first control data, is generated. Based on the first control data of the first test pattern, a first fault data is generated by applying the first scan-in data of the first test pattern to scan flops in a test circuit of the integrated circuit. If the first fault data indicates that a fault may be present in the integrated circuit, a second test pattern, including a second scan-in data and a second control data is generated.

Localizing fault flop in circuit by using modified test pattern

A core circuit that can be connected in a hierarchical manner, and configured to test a multiple circuits is disclosed. The core circuit includes at least one real input for receiving scan-in data for controlling operation of the core circuit. The core circuit further includes an input register coupled to the at least one real input and configured to store data. The core circuit further includes at least one scan chain coupled a subset if registers of the register chain and configured to generate scan-out data representing the presence of faults in an circuit. Furthermore, the core circuit includes at least one control pseudo-output coupled to the input register and configured to route at least a subset of the data to another register chain in the core circuit or to another core circuit.

Hierarchical testing architecture using core circuit with pseudo-interfaces

Roughly described, a scan-based test architecture is optimized in dependence upon the circuit design under consideration. In one embodiment, a plurality of candidate test designs are developed. For each, a plurality of test vectors are generated in dependence upon the circuit design and the candidate test design, preferably using the same ATPG algorithm that will be used downstream to generate the final test vectors for the production integrated circuit device. A test protocol quality measure such as fault coverage is determined for each of the candidate test designs, and one of the candidate test designs is selected for implementation in an integrated circuit device in dependence upon a comparison of such test protocol quality measures. Preferably, only a sampling of the full set of test vectors that ATPG could generate, is used to determine the number of potential faults that would be found by each particular candidate test design.

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Cupertino, CA, United States of America

Rohit Kapur