International Business Machines Corporation

Cadence Design Systems, Inc.

Magma Design Automation, Inc.

R Dean Adams

Steven Lee Gregor

Thomas J Eckenrode

Kamran K Zarrineh

Gerard M Salem

Patrick R Hansen

Timothy J Von Reyn

Michael Richard Ouellette

Harold Pilo

Donald Albert Evans

Robert E Busch

Garrett Stephen Koch

Roy Childs Flaker

Ronald J Prilik

Dwayne M Burek

Gary S Koch

Robert Abbott

Xiaoliang Bai

Edmond S Cooley

George E Rudgers

Aneesha P Deo

A BIST system that utilizes ECC to correct single bit errors in a given memory word at a given address, the ECC having a maximum number of bit errors it can correct in the given memory word. A first set of gates is coupled to an array of memory cells that stores a plurality of memory words, each at a given address. The first set of gates provides bit outputs indicative of errors in a given memory word while the given memory word is under test. A circuit coupled to respective outputs of the first set of gates determines if a number of errors in the memory word under test exceeds the maximum number of errors correctable by the ECC.

Testing of ECC memories

A memory logic built-in self-test ('BIST') includes slow speed controller-to-collar signals, while allowing collars to test memories at full speed. A controller is configured to include control features and address, data, read/write, output evaluation, and redundancy calculation values are configured within the collars. The controller is further configured to handle scheduling of the collars and diagnostics interfacing. In addition, the collars are configured to allow BIST testing to be run serially, in parallel, or in groups. Collars are also configured to send diagnostic results back to the controller based on the initialization of the respective collars, thus providing a central interface for the diagnostics results.

Asynchronous control of memory self test

A microcode programmable built-in-self-test (BIST) circuit and method for testing a multiported memory via multiple ports, either simultaneously or sequentially, as directed by a microcode instruction word. The microcode instruction word contains a plurality of executable subinstructions and one bit of information that controls whether the test operations prescribed in the plurality of subinstructions shall be executed in parallel or in series. The executable subinstructions are dispatched by a primary controller to subcontrollers which perform test operations at each port according to the subinstructions. The microcode programable BIST architecture flexibly facilitates the testing of multiple devices, multiported devices, including multiported memory structures and complex dependent multiported memory structures. The BIST supports in-situ testing of the functionality of the memory at wafer, module, and burn-in, as well as system-level testing.

Programable multi-port memory BIST with compact microcode

A fault recovery system for an array of memory cells. A register stores data indicating addresses of multi-cell fails and single-cell fails. A first fault correction system accesses data from the register to fix both multi-cell fails and single-cell fails. A second fault correction system does not access said register and fixes single-cell fails. During testing, if a multi-cell fail is detected the register stores its address by deleting an address of a single-cell fail if the register is full.

Optimized ECC/redundancy fault recovery

A method and system for testing multiported memories, especially when one or more of the ports are not directly accessible without intervening logic. The method and system segregates the multiported memory into at least two portions which are then used for testing the one or more ports which are not directly accessible.

Method and apparatus for testing multi-port memories

A system and methodology for testing memory in an integrated circuit implementing BIST testing to calculate row and column redundancy and enable replacement of a defective row or column of memory cells. The system comprises circuitry for detecting a first single memory cell failure in a row; and, recording the I/O value of the first Single Cell Fail (SCF). A circuit is provided for detecting whether more than one single cell failure has occurred for a tested row, and, in response to detecting a second SCF, comparing recorded I/O value of the subsequent tested row, with the I/O value associated with the first failed memory cell. Upon detection of defective bits, the defective column and row of memory having corresponding defective bits set is replaced.

Two-dimensional redundancy calculation

A built-in self test system () and method for two-dimensional memory redundancy allocation. The built-in self test system is adapted to allocate two redundant columns () and one redundant row () to an embedded memory () as needed to repair single cell failures (SCFs) within the rows () and columns of the memory. The self-test system includes a left-priority encoder (), a right-priority encoder (), and a greater-than-two detector (). The left-priority encoder encodes the location of the first SCF most proximate the most-significant bit of the corresponding word. The right-priority encoder encodes the location of the first SCF most proximate the least-significant bit of the corresponding word. The greater-than-two detector determines whether a word contains more than two SCFs. If the greater-than-two detector detects that a word contains more than two SCFs, the built-in self test system identifies the corresponding row as being a must-fix row, since the number of SCFs exceeds the number of redundant columns.

Built-in self test system and method for two-dimensional memory redundancy allocation

The functionality of a programmable memory built-in self-test (BIST) arrangement for testing an embedded memory structure of an integrated circuit is extended to system level testing to ascertain operability of the system after the integrated circuits and boards including them have been placed in service in larger systems, by generating default test signals which are loaded in an instruction store module when test instructions are not provided from an external tester. This additional utility of the BIST arrangement, increases efficiency of chip space utilization and improves the system level test. Loading of test instructions from an external tester during chip manufacture and/or board assembly is unaffected.

System initialization of microcode-based memory built-in self-test

A method for testing memory cells for data retention faults is disclosed. A first logical value is stored in a first cell, and a second logical value is stored in a second cell of a memory device. The second cell shares the same column with the first cell. The bitlines associated with the first and second cells are prevented from being precharged before the second cell can be read. After the second cell has been read repeatedly, the first cell is read, and the bitlines associated with the first and second cells are precharged. At this point, a data retention fault is determined to have occurred if the first cell does not contain the first logical value.

Method and apparatus for testing memory cells for data retention faults

A finite state machine (FSM) is used to generate, in real time, potentially long sequences of signals which control generation of signals for application to a memory structure during a self-test procedure which is provided in hardware on the same chip with the memory structure. The FSM-based instruction generator requires much less area than is required for storage of a corresponding number of microcode instructions and allows the built-in self-test (BIST) controller to have a modular architecture permitting re-use of hardware designs for the BIST arrangement with consequent reduction of elimination of design costs of the BIST arrangement to accommodate new memory designs. The sequential nature of the operation of a finite state machine as it progresses through a desired sequence of states is particularly well-suited to controlling capture of signals where access to high. speed data transfer circuits cannot otherwise be accommodated.

Programmable memory built-in self-test combining microcode and finite state machine self-test

A semiconductor memory device having resistive bitline contact testing includes memory cells, and wordline logic devices for concurrently activating two adjacent memory cells. The two adjacent memory cells are activated concurrently to allow higher current through a bitline contact for improved detection of resistive bitline contacts. A test cell may also be included to test the integrity of the bitline contact.

Semiconductor memory device having resistive bitline contact testing

A method and apparatus for detecting whether dynamic logic circuits are precharging properly. The method and apparatus uses a narrowed reset pulse to verify precharging is occurring as designed.

Method and apparatus for testing dynamic logic using an improved reset pulse

An on-chip test circuit for evaluating on-chip signals for a semiconductor memory chip includes an on-chip signal associated with a memory circuit on the chip; said on-chip signal having a signal characteristic to be evaluated; an input circuit for receiving an off-chip test signal; and a test circuit that compares said on-chip signal and said test signal.

On-chip test circuit for evaluating an on-chip signal using an external

A built-in self-test (BIST) apparatus and method for testing an integrated circuit are disclosed which enable capture of failure data for a selected failure. The BIST apparatus comprises a clock generator, which generates at least a first clock signal, and a built-in self-tester, which applies predetermined input data patterns to the integrated circuit in response to the first clock signal. In addition, the BIST apparatus includes a data comparator for comparing output data received from the integrated circuit with expected output data. The data comparator detects a failure within the integrated circuit when the output data received from the integrated circuit differs from the expected output data. The BIST apparatus further includes a clock controller that disables the first clock signal in response to the detection of a selected occurrence of a failure. By enabling testing of the integrated circuit to be halted upon the occurrence of a selected failure, failure analysis of the integrated circuit is enhanced.

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St. George, VT, United States of America

R Dean Adams