Freescale Semiconductor,inc.

Nxp Usa, Inc.

Yanzhuo Wang

Fuchen Mu

Chen He

Richard Eguchi

Jon Scott Choy

Benjamin A Schmid

Craig T Swift

Richard K Eguchi

A method and memory for stressing a plurality of non-volatile memory cells is provided. The method includes entering a memory cell stressing mode and providing one or more erase stress pulses to the plurality of non-volatile memory cells; determining that a threshold voltage of at least a subset of the plurality of non-volatile memory cells has a first relationship that is either greater than or less than a first predetermined voltage; providing one or more program stress pulses to the plurality of memory cells; and determining that the threshold voltage of at least a subset of the plurality of memory cells has a second relationship to a second predetermined voltage that is different than the first relationship.

Method and apparatus for stressing a non-volatile memory

Methods and systems are disclosed for extended erase protection for non-volatile memory (NVM) cells during embedded erase operations for NVM systems. The embodiments described herein utilize an additional threshold voltage (Vt) check after soft programming operation within an embedded erase operation completes to provide extended erase protection of NVM cells. In particular, the threshold voltages for NVM cells are compared against a threshold voltage (Vt) check voltage (V) level and an additional embedded erase cycle is performed if any NVM cells are found to exceed the threshold voltage (Vt) check voltage (V) level. The threshold voltage (Vt) check voltage (V) level can be, for example, a voltage level that is slightly higher than an erase verify voltage (V) level and lower than read voltage level (V).

Extended protection for embedded erase of non-volatile memory cells

A method of soft programming a non-volatile memory (NVM) array includes determining a first number based on a temperature of the NVM array and applying the first number of soft program pulses to a section of the NVM array. A first soft program verify of the section of the NVM array is then performed for a first time after completing the applying the first number of soft program pulses.

Non-volatile memory (NVM) with variable verify operations

Methods and systems are disclosed for adjusting read/verify bias conditions for non-volatile memory (NVM) cells to improve performance and product lifetime of NVM systems. System embodiments include integrated NVM systems having a NVM controller, a bias voltage generator, and an NVM cell array. Further, the NVM systems can store performance degradation information and read/verify bias condition information within storage circuitry. The disclosed embodiments adjust read/verify bias conditions for the NVM cells based upon performance degradation determinations, for example, temperature-based performance degradation determinations.

Methods and systems for adjusting NVM cell bias conditions for read/verify operations to compensate for performance degradation

A method includes an erase of a plurality of blocks of memory cells in which the memory cells within a block are simultaneously erased. The erase of each block of the plurality of blocks is performed using an erase pulse applied multiple times. The erase pulse is applied to the plurality of blocks in parallel. An erase verify is performed after each application of the erase pulse. After a number applications of the erase pulse, it is determined if a condition comprising one of a group consisting of any memory cell has been more erased than a first predetermined amount and any memory cell has been erased less than a second predetermined amount has been met. If the condition has been met, erasing is continued by applying the erase pulse to the block having the memory cell with the condition independently of the other blocks of the plurality of blocks.

Adaptive erase methods for non-volatile memory

A non-volatile memory built-in self-trim mechanism is provided by which product reliability can be improved by minimizing drift of reference current used for accessing the non-volatile memory and for performing initial trimming of the reference current. Embodiments perform these tasks by using an analog-to-digital converter to provide a digital representation of the reference current (Iref) and then comparing that digital representation to a stored target range value for Iref and then adjusting a source of Iref accordingly. For a reference current generated by a NVM reference bitcell, program or erase pulses are applied to the reference cell as part of the trimming procedure. For a reference current generated by a bandgap-based circuit, the comparison results can be used to adjust the reference current circuit. In addition, environmental factors, such as temperature, can be used to adjust the measured value for the reference current or the target range value.

Built-in self trim for non-volatile memory reference current

Methods and systems are disclosed for adaptive erase recovery of non-volatile memory (NVM) cells within NVM systems. The adaptive erase recovery embodiments adaptively adjust the erase recovery discharge rate and/or discharge time based upon the size of NVM block(s) being erased and operating temperature. In one example embodiment, the erase recovery discharge rate is adjusted by adjusting the number of discharge transistors enabled within the discharge circuitry, thereby adjusting the discharge current for erase recovery. A lookup table is used to store erase recovery discharge rates and/or discharge times associated with NVM block sizes to be recovered and/or operating temperature. By adaptively controlling erase recovery discharge rates and/or times, the disclosed embodiments improve overall erase performance for a wide range of NVM block sizes while avoiding possible damage to high voltage circuitry within the NVM system.

Adaptive erase recovery for non-volatile memory (NVM) systems

A sense amplifier is configured to sense a current from a selected bit cell of a non-volatile memory array and compare the sensed current to a reference current to determine a logic state stored in the bit cell. A controller is configured to perform a program/erase operation on at least a portion of the memory array to change a logic state of at least one bit cell of the portion of the memory array; determine a number of program/erase pulses applied to the at least one bit cell during the program/erase operation to achieve the change in logic state; and when the number of program/erase pulses exceeds a pulse count threshold, adjust the reference current of the sense amplifier for a subsequent program/erase operation.

Non-volatile memory (NVM) with dynamically adjusted reference current

Methods and systems are disclosed for dynamic healing of non-volatile memory (NVM) cells within NVM systems. The dynamic healing embodiments described herein relax damage within tunnel dielectric layers for NVM cells that occurs over time from charges (e.g., holes and/or electrons) becoming trapped within these tunnel dielectric layers. NVM operations with respect to which dynamic healing processes can be applied include, for example, erase operations, program operations, and read operations. For example, dynamic healing can be applied where performance for the NVM system degrades beyond a selected performance level for an NVM operation, such as elevated erase/program pulse counts for erase/program operations and bit errors for read operations. A variety of healing techniques can be applied, such as drain stress processes, gate stress processes, and/or other desired healing techniques.

Dynamic healing of non-volatile memory cells

A semiconductor device comprises an array of memory cells. Each of the memory cells includes a tunnel dielectric, a well region including a first current electrode and a second current electrode, and a control gate. The first and second current electrodes are adjacent one side of the tunnel dielectric and the control gate is adjacent another side of the tunnel dielectric. A controller is coupled to the memory cells. The controller includes logic to determine when to perform a healing process in the tunnel dielectric of the memory cells, and to apply a first voltage to the first current electrode of the memory cells during the healing process to remove trapped electrons and holes from the tunnel dielectric.

Structure and method for healing tunnel dielectric of non-volatile memory cells

A memory includes a plurality of blocks in which each block includes a plurality of memory cells. The memory includes a set of charge pumps which apply voltages to the plurality of blocks. A method includes selecting a block of the plurality of memory blocks; determining an array size of the selected block; determining a set of program/erase voltages based on the array size and temperature from a temperature sensor; and programming/erasing the selected block, wherein the set of program/erase voltages are applied by the set of charge pumps during the programming/erasing of the selected block.

Non-volatile memory (NVM) with block-size-aware program/erase

Non-volatile memory (NVM) systems and related methods adjust program/erase bias conditions for non-volatile memory (NVM) cells to improve performance and product lifetime of NVM systems. System embodiments include integrated NVM systems having an NVM controller, a bias voltage generator, and an NVM cell array. Further, the NVM systems can store performance degradation information and program/erase bias condition information within storage circuitry. The disclosed embodiments adjust program/erase bias conditions for the NVM cells based upon performance degradation determinations, for example, temperature-based performance degradation determinations and interim verify based performance degradation determinations.

Methods and systems for adjusting NVM cell bias conditions for program/erase operations to reduce performance degradation

A method of erasing a non-volatile memory (NVM) array includes determining a first number based on a temperature of the NVM array. Erase pulses of the first number are applied to the NVM array. A first verify of the NVM is performed for a first time after commencing the applying after the first number has been reached.

Methods and systems are disclosed for making temperature-based adjustments to bias conditions for non-volatile memory (NVM) cells to improve performance and product lifetime of NVM systems. System embodiments include integrated NVM systems having an NVM controller, a bias voltage generator, and an NVM cell array. Further, the NVM systems can store temperature-based bias condition information in storage circuitry. The disclosed embodiments select and apply bias conditions for the NVM cells based upon temperature measurements.

Methods and systems for adjusting NVM cell bias conditions based upon operating temperature to reduce performance degradation

A semiconductor memory device comprises a memory controller, and an array of memory cells coupled to communicate with the memory controller. The memory controller is configured to perform a first soft program operation using first soft program voltages and a first soft program verify level, and determine whether a first charge trapping threshold has been reached. When the first charge trapping threshold has been reached, a second soft program operation is performed using second soft program voltages and a second soft program verify level.

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Austin, TX, United States of America

Yanzhuo Wang