International Business Machines Corporation

James W Dawson

Donald W Plass

Kenneth J Reyer

Thomas J Knips

Paul Alan Bunce

John D Davis

Noam Jungmann

Elazar Kachir

Douglas J Malone

Rajiv V Joshi

Erik L Hedberg

Rouwaida N Kanj

Robert Dean Adams

Henry A Bonges, Iii

Tom Y Chang

Michael Nicewicz

Udi Nir

Panagiotis A Phillips

George A DeLuca

Ehud Nir

A digital voltage boost circuit, optionally working in parallel with an analog voltage regulator, periodically injects a constant amount of current each cycle into the bit line of a high density memory array to eliminate the bias voltage reduction which would otherwise occur. This results in a much faster recovery time and reduces the semiconductor real estate required. A pulse generator in the boost circuit generates one or more current modulation signals which control corresponding current supply devices in a current source. The boost circuit drives a constant amount of current to the bias voltage node each memory cycle.

Digital voltage boost circuit

Systems and methods for determining optimal memory device precharge voltages are provided herein. In addition, systems and methods for providing localized sense amplification and circuit assist circuitry are described herein. Embodiments provide for determining precharge multipliers that may be used to determine the optimal precharge voltage based on a precharge source voltage. According to embodiments, the precharge source voltage may be Vdd or Vcs. Optimizing the precharge voltage maximizes memory device performance and functional characteristics, including, but not limited to, stability, efficiency, power, writability, and reliability.

Systems and methods for memory device precharging

A method and apparatus for implementing ABIST data compression and serialization for memory built-in self test of SRAM with redundancy. The method includes providing detection signals asserted for one failing data out, two failing data outs, and greater than two failing data outs. The method also includes individually encoding the failing bit position of each corresponding failing data out with a binary representation value corresponding therewith. The method further includes serializing results of the providing detection signals and the individually encoding, and transmitting results of the serializing to a redundancy support register function on a single fail buss.

ABIST data compression and serialization for memory built-in self test of SRAM with redundancy

A clock control method and apparatus are provided employing a clock control circuit which generates an array clock for a memory array from a system clock and a reset control signal. The reset control signal is one of a plurality of input control signals to the clock control circuit. When the system clock is below a predefined frequency threshold, the reset control signal is an array tracking reset signal, wherein the active pulse width of the array clock is system clock frequency independent, and when the system clock is above the predefined frequency threshold, the reset control signal is a mid-cycle reset signal, meaning that the active pulse width of the array clock is system clock frequency dependent. A bypass signal is provided as a third input control signal, which when active causes the clock control circuit to output an array clock which mirrors the system clock.

Clock control method and apparatus for a memory array

A decoder circuit includes a pulse powered stage having a plurality of fan-in inputs thereto, a dynamic stage fed by the pulse powered stage, and a replica node selectively coupled to an output node of the pulse powered stage by a pass device. The pass device and the dynamic stage are controlled by a clock signal so as to enable a self-timed evaluation of the pulse-powered stage with a clocked enablement of the dynamic stage.

Fast pulse powered NOR decode apparatus for semiconductor devices

A decoder circuit includes a pulse powered stage having a plurality of fan-in inputs thereto, a dynamic stage fed by the pulse powered stage, and a replica node selectively coupled to an output node of the pulse powered stage by a pass device. The pass device and the dynamic stage are controlled by a clock signal so as to enable a self-timed evaluation of the pulse-powered stage with a clocked enablement of the dynamic stage. A pull up device restores the dynamic stage to a precharged condition, the pull up device controlled by a second clock signal independent of the first clock signal.

Fast pulse powered NOR decode apparatus with pulse stretching and redundancy steering

A bitline selection apparatus for a semiconductor memory device includes a first local bitline pair and a second local bitline pair selectively coupled to a global bitline pair, each of the first and second local bitline pairs including a true bitline and a complementary bitline. Each of the true bitlines is selectively coupled to a common true node through an n-type pass device and a p-type pass device in parallel therewith, and each of the complementary bitlines is selectively coupled to a common complementary node through an n-type pass device and a p-type pass device in parallel therewith.

High density bitline selection apparatus for semiconductor memory devices

A global and local read control synchronization method and system are provided for a memory array configured with multiple memory subarrays. Address signals are decoded to activate based thereon subarray select signals and a cumulative subarray select signal. The cumulative subarray select signal goes active whenever a subarray select signal goes active, and therefore, each pulse of the cumulative subarray select signal is synchronous with one pulse of the subarray select signals. Local read control signals for the multiple memory subarrays are obtained employing the subarray select signals, and at least one global read control signal for the memory array is obtained employing the cumulative subarray select signal. In one example, the memory array has a hierarchical bitline architecture.

Global and local read control synchronization method and system for a memory array configured with multiple memory subarrays

Method and system for testing a memory array having a non-uniform binary address space. The test system includes a test engine for generating addresses for the memory array and for generating and applying data patterns to the memory array. The test engine has an address generator including a series combination of a linear register and a binary counter for generating the non-uniform address.

Non-binary address generation for ABIST

An array built-in, on-chip self test system for testing a memory array and a method of testing the memory array. The memory array has data input ports, data output ports, and address ports, and a data control subsystem, an address control subsystem, and a comparator. The data control subsystem generates and applies deterministic data patterns to the data input ports of the memory array. The address control subsystem generates addresses for application to the memory array in coordination with said data control subsystem, and includes a sequence counter, a count rate controller for the sequence controller, a count rate controller divider to control the number of cycles per address, an address controller to provide granular control of addresses, and an X-OR gate receiving an input from a sequence counter and from the address controller, the X-OR gate outputting an address bit to the memory array. The comparator compares the data inputted to the data input ports of the memory array from the data control subsystem with the data outputted from the data output ports of the memory array.

ABIST address generation

A memory redundancy control apparatus includes a static compare stage configured to compare bits of a requested memory address to corresponding fuse information bits representing a defective memory address. A dynamic stage is configured to receive outputs of the static compare stage, with an output of the dynamic stage being precharged so as to initially deactivate primary subarray decoding circuitry. The dynamic stage is further triggered by a clock signal thereto. Upon activation of the clock signal, the output of the dynamic stage remains precharged whenever a match exists between the requested memory address and the defective memory address, and the output of the dynamic stage is discharged whenever a mismatch exists between the requested memory address and the defective memory address. A delay tracking clock generator is configured to generate a delay tracking clock signal with respect to the dynamic stage, to gate the output of the dynamic stage to spare subarray decoding circuitry, wherein the spare subarray decoding circuitry is activated whenever the output of the dynamic stage remains precharged following activation of the clock signal.

Apparatus and method for implementing multiple memory redundancy with delay tracking clock

An apparatus for implementing multiple memory column redundancy within an individual memory array includes a plurality of memory array elements internally partitioned into at least a pair of subcolumn elements. At least one spare memory element is configured at a size corresponding to one of the subcolumn elements. An input redundancy multiplexing stage and an output redundancy multiplexing stage are configured for steering around one or more defective memory array elements, and an input bit decoding stage and an output bit decoding stage are configured for implementing an additional, external multiplexing stage with respect to the input redundancy multiplexing stage and the output redundancy multiplexing stage.

Method and apparatus for implementing multiple column redundancy for memory

A method for testing SOI technology memory circuits, such as in SRAMs, for weak SOI cells, uses a reset test circuit with a wordline pulse width control circuit which can be implemented without performance impact and allows using unused silicon to minimize area usage impact and permits screening of integrated SOI memory array circuits for weak SOI cells using the test reset circuit to selectively change the wordline pulse width to a reduced time while the memory cell bit select and write signals turn off at normal times to stress the cell write margin. Further, during test, the word line pulse width can be extended by blocking the reset signal of the reset path test circuit to the word path to produce a longer than normal pulse width. In addition, during a test for normal operations the reset signal is allowed to pass through a pass gate multiplexer of the reset test circuit.

SOI cell stability test method

A redundancy system formed on a semiconductor chip is provided which includes circuits for testing a memory array to locate a faulty element therein, a register for storing an address of the faulty element and electrical fuses blown in response to binary digits of the address stored in the register upon application of an enable signal from a single input to the semiconductor chip. The enable signal passes through logic circuits on the chip such that the fuses cannot be programmed or blown unless the enable signal is present. An address decoder coupled to outputs from the fuses substitutes a redundant element for the faulty element.

Module level electronic redundancy

On-chip circuitry facilitates fuse testing in customized integrated circuits. The circuitry has specific application in testing fuse redundancy high end memories. A latch assisted fuse testing (LAFT) methodology employs an on-chip latch stack which can be used in place of the fuses. The latches in the stack are programmable and can perform the same function as the fuses during chip operation. This allows testing or experimentation to be performed nondestructively, without blowing any fuses. In one particular application of the invention, memory arrays with redundant blocks on a chip are provided with the on-chip latch stack. After the tests based on previously generated error data are performed using the latch stack, fuses are blown to repair the memory array by replacing defective memory blocks with redundant blocks.

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Poughkeepsie, NY, United States of America

James W Dawson