Abstract: A memory management component can track the amount of time between erase cycles for a particular memory region, and can manage memory region such that the regions are given sufficient time to rest and recover, or are given at least as much rest time as is practical, before being subject to an erase cycle. A reclamation management component can reclaim memory region that have invalid data stored therein, and can reclaim regions on a just-in-time basis when practical, and can determine which regions to reclaim based on various factors, such as the amount of time since a region was last erased, and the number of programming errors associated with a region. The memory management component can thereby optimize the useful life, minimize or reduce loss of margin in memory regions, and minimize or reduce programming errors of memory regions, of non-volatile (e.g., flash) memory.

Abstract: A method for erasing an EEPROM cell which reduces the need for monitoring algorithms. The potential at the erase gate is initially raised and the potential at the control gate is lowered to cause FN tunneling through the erase gate. A subsequent soft programming step is employed to raise the potential at the control gate to a value sufficient to cause FN tunneling to start though the oxide of the transistor. A new memory device structure suitable for practicing this method employs a transistor having a floating gate, where a data value is stored as charged on the floating gate; a control gate; a control gate capacitor coupling the control gate to the floating gate; an erase gate; an erase gate capacitor coupling the erase gate to the floating gate; and an erase control circuit.

Abstract: A system and method for determining a SONOS VT window using a current sensing scheme is disclosed. The present invention creates a first current path and a second current path through the volatile and non-volatile sections of an nvSRAM memory cell. The erase threshold voltage of the first edge of the window is determined when current is detected in the first path. The program voltage of the second edge of the window is determined when current is detected in the second path. Accordingly, the voltage used to power a plurality of SONOS transistors may be set using the values of the first and second threshold edges to determine the VT window.

Abstract: An apparatus for estimating a frequency of access to a storage device that includes a flash memory and a controller for controlling the flash memory includes interface. Data is written into the flash memory in units of a page and being erased from the flash memory in units of a block consisting of pages. The interface is supplied with an internal signal transferred between the flash memory and the controller, configured to recognize the internal signal, and outputs the internal signal as an input signal. An erasure sequence detection section outputs a detection signal when address data is followed by an erasure command requesting erasure of data in the block specified by the address data in the input signal. An address holding section holds address data in the internal signal, and outputs held address data as erasure address data when supplied with the detection signal.

Abstract: Techniques are provided for performing multi-pass erase. An erase command is received at a storage area network (SAN) switch in a storage area network. The erase command is associated with a block of data on a target device. A virtual initiator is determined for performing the erase command on the block of data. Multiple bit patterns are generated using a multi-pass erase algorithm. The multiple bit patterns are generated for writing over the block of data on the target device. Repeated writes are performed over the block of data using the bit patterns. The block of data is repeatedly overwritten to remove remanence of the block of data on the target device.

Abstract: Embodiments of the present disclosure provide methods, devices, modules, and systems for healing non-volatile memory cells. One method includes biasing a first select gate transistor coupled to a string of memory cells at a first voltage, biasing a second select gate transistor coupled to the string at a second voltage, applying a first healing voltage to a first edge word line in order to extract charge accumulated between the first select gate transistor and a first edge memory cell stack of the string, and applying a second healing voltage to a second edge word line in order to extract charge accumulated between the second select gate transistor and a second edge memory cell stack of the string.

Abstract: Provided are a SONGS type nonvolatile or flash memory device and related programming/erasing methods. The device has a deep well region of a first conductive type that isolates a well region of a second conductive type from a substrate to enhance programming and erasing operation characteristics. In the erasing method, first electrons are erased by one of Hot Hole Injection (e.g., gate-to-drain Hot Hole Injection) or tunneling in a first step, and second electrons that are not erased in the first step are erased by the other of tunneling (e.g., gate-to-body tunneling) or HHI in a second step. Preferably, a time gap intervenes between the first and second steps.

Abstract: An erase method for a non-volatile memory device having a defined erase unit divided into first and second inner erase units includes; applying an erase voltage to at least one of the first and second inner erase units in accordance with respective states of corresponding first and second fail flags, after applying the erase voltage to the at least one of the first and second inner erase units, performing an erase verification on the at least one of the first and second inner erase units, and updating the at least one of the first and second fail flags in accordance with erase verification results.

Abstract: A method is provided, which can improve the efficiency of device design by estimating the variation of threshold voltage according to the pulse widths of applied voltage for a semiconductor device in mass product.

Abstract: A method and apparatus are provided for adaptive memory cell overerase compensation. A semiconductor memory device (100) is provided for performing the adaptively compensating erase verify operation (500, 600). The memory device (100) includes at least one word line (402). One or more memory cells (200) and one or more reference cells (406, 408) are connected to the word lines (402), where the one or more reference cells (406, 408) include an erased reference cell (408) connected to each word line (402). The method (500, 600) for adaptive memory cell overerase compensation includes determining an erase verify gate voltage (506, 608) utilizing the erased reference cell(s) (408) and verifying an erase voltage (514) of the memory cells (200) in response to the erase verify gate voltage (512, 614).

Abstract: A memory cell includes a first transistor and a second transistor. The first transistor is configured as an erase capacitor, and the second transistor is configured as a program transistor. Gates of the first and second transistors are coupled together to form a floating gate. During an erase operation, a first voltage (like 12V-24V) is applied to the first transistor, such as to a source, a body, and a drain of the first transistor. A second voltage (like ground) is applied to the second transistor, such as to a source and a body of the second transistor. A drain of the second transistor could be grounded. The first and second voltages cause electron discharge from the floating gate through the first transistor and electron injection through the second transistor onto the floating gate. This helps to prevent an over-erase condition from forming in the memory cell.

Abstract: A non-volatile memory can have multiple blocks erased in parallel for a relatively few number of erase operations. This saves time for the user in the set-up of the memory because the erase operation is relatively slow. Problems with parallel erase relate to different blocks having different program/erase histories with the result that the blocks with different histories erase differently. Thus, after a predetermined number of erase cycles are performed, the ability to parallel erase is prevented. This is achieved by allowing parallel erasing operations until the predetermined number of erase operations have been counted. After that predetermined number has been reached, a parallel erase mode disable signal is generated to prevent further parallel erase cycles. The count and the predetermined number are maintained in a small block of the non-volatile memory that is inaccessible to the user.

Abstract: A method for erasing a non-volatile memory device performs a block erase operation. The cells are then soft programmed and erase verified to determine if the threshold voltages indicate erased cells. A target cell is programmed to a first threshold voltage and verified. Adjacent cells are programmed and verified. The parasitic capacitance between the target cells and the adjacent cells causes the threshold voltage of the target cell to increase to a new threshold voltage with the programming of the adjacent cells. A difference between the new threshold voltage and the first threshold voltage is determined. If the difference is greater than or equal to a predetermined threshold, the target cell is soft programmed until the difference is less than the predetermined threshold.

Abstract: A method for programming a flash memory cell comprises providing input data to the flash cell and providing a segmented programming pulse to the flash memory cell. The segmented programming pulse includes programming segments, each successive programming segment including a programming potential higher than the programming potential used in a previous programming segment, each programming segment followed by a zero-potential compare segment. The output of the flash memory cell is compared with the input data during the compare segment after each programming segment. The segmented programming pulse is terminated if the output of the flash memory cell matches the input data. The programming potential in each programming segment is increased during the programming segment. The programming potential in successive segments is either is increased or stepped up to the final value of the previous programming segment.

Abstract: A method and apparatus are provided for adaptive memory cell overerase compensation. A semiconductor memory device (100) is provided for performing the adaptively compensating erase verify operation (500, 600). The memory device (100) includes at least one word line (402). One or more memory cells (200) and one or more reference cells (406, 408) are connected to the word lines (402), where the one or more reference cells (406, 408) include an erased reference cell (408) connected to each word line (402). The method (500, 600) for adaptive memory cell overerase compensation includes determining an erase verify gate voltage (506, 608) utilizing the erased reference cell(s) (408) and verifying an erase voltage (514) of the memory cells (200) in response to the erase verify gate voltage (512, 614).

Abstract: Methods and structures are described for increasing a memory operation window in a charge trapping memory having a plurality of memory cells in which each memory cell is capable of storing multiple bits per memory cell. In a first aspect of the invention, a first method to increase a memory operation window in a two-bit-per-cell memory is described by applying a positive gate voltage, +Vg, to erase a memory cell to a negative voltage level. Alternatively, a negative gate voltage, ?Vg, is applied to the two-bit-per-cell memory for erasing the memory cell to a negative voltage level. A second method to increase a memory operation window is to erase a memory cell to a voltage level that is lower than an initial voltage threshold level. These two erasing methods can be implemented either before a programming step (i.e., a pre-program erase operation) or after a programming step (i.e., a post-program erase operation).

Abstract: A memory device is provided including circuitry for correcting an over-erased memory cell in the memory device. The memory device may include a substrate. A control gate and a floating gate may be formed over the substrate. The memory device may include a source region and a drain region. A first resistive element may be coupled between the source region and the control gate.

Abstract: A flash memory device and a method of erasing memory cells in a flash memory device are provided. A first post program operation is performed on erased memory cells having a threshold voltage lower than a first program verify voltage. A second post program operation is performed on erased memory cells having a threshold voltage lower than a second program verify voltage. The second program verify voltage is lower than the first program verify voltage.

Abstract: A soft programming pre-charge voltage provides boosting control during soft programming operations for non-volatile memory devices. A pre-charge voltage can be applied to the word lines of a block of memory cells to enable pre-charging of the channel region of a NAND string to be inhibited from soft programming. The level of boosting in the channel region of the inhibited NAND string is governed by the pre-charge voltage and the soft programming voltage. By controlling the pre-charge voltage, more reliable and consistent channel boosting can be achieved. In one embodiment, the pre-charge voltage is increased between applications of the soft programming voltage to reduce or eliminate a rise in the channel's boosted potential. In one embodiment, the soft programming pre-charge voltage level(s) is determined during testing that is performed as part of a manufacturing process.

Abstract: A NROM memory device includes an array of memory cells and first and second bit lines. The first and second bit lines are coupled to opposite sides of the memory cells. During an erase operation, one of the sides of the memory cells receives a positive voltage and the other side couples to a common node or a limited current source. Methods are also disclosed that can easily screen for marginal memory cells based on a threshold voltage distribution of the memory cells.

Abstract: In a flash memory device, a multi-block erase operation is performed by applying stepwise increasing erase voltages to selected memory blocks during a first erase period and then applying fixed erase voltages to the selected memory blocks during a second erase period. Once a selected memory block is successfully erased in the first erase period, the device prevents erase voltages from being applied to the selected memory block for a remaining part of the first erase period.

Abstract: A method for preventing a memory from generating a leakage current is disclosed. The memory includes a boundary memory cell and a neighboring memory cell. The neighboring memory cell is adjacent to the boundary memory cell. The method includes the following step. The first terminal of the neighboring memory cell is connected to the second terminal through a metal line.

Abstract: Soft programming is performed to narrow the threshold voltage distribution of a set of erased memory cells. Soft programming can shift the threshold voltage of memory cells closer to a verify level for the erased state. A set of memory cells can be soft programmed by soft programming portions of the set to provide more consistent soft programming rates and threshold voltages. A first soft programming pulse can be applied to a first group of cells of the set while inhibiting soft programming of a second group of cells. A second soft programming pulse can then be applied to the second group of cells while inhibiting soft programming of the first group of cells. A small positive voltage of lower magnitude than the soft programming pulses can be applied to the group of cells to be inhibited. The size of the small positive voltage can be chosen so that each memory cell of the set will experience similar capacitive coupling effects from neighboring transistors when it is undergoing soft programming.

Abstract: A set of memory cells can be erased by individually erasing portions of the set in order to normalize the erase behavior of each memory cell and provide more consistent erase rates. An erase voltage pulse can be applied to the set of memory cells with a first group of cells biased for erase and a second group biased to inhibit erase. A second erase voltage pulse can then be applied with the second group biased for erase and the first group biased to inhibit erase. The groups are chosen so that the erase potentials for the cells in the first subset during the first pulse are about equal, so that the erase potentials for the cells in the second subset during the second pulse are about equal, and so that the erase potentials for the cells of the first subset are about the same as the erase potentials for the cells of the second subset.

Abstract: A method for performing an erase operation is disclosed in a non-volatile memory having a plurality of memory cells. At least one memory cell is programmed having a threshold voltage level in a first region before programming, and after programming the memory cell has a threshold voltage level in a second region, wherein the second region is higher in threshold voltage than the fist region. The erasing operation implements a programming of memory bits that can inject negative charge carriers or electrons into a memory cell instead of using the conventional technique of injecting hot holes into the memory cell. This can avoid room temperature drift and charge loss caused by hot hole injection.

Abstract: According to a method of erasing data in a non-volatile semiconductor memory device, block-round type overerase verify is performed. Specifically, overerase verify and write back are performed sequentially from a first address to a last address. That is, even when a write back pulse is applied after a certain address is selected and verify is performed, address increment from one address to another is performed, regardless of whether verify has been performed or not. Therefore, it is not that the same address is cumulatively rewritten, but write back to a memory cell corresponding to a defective address is sequentially and gradually performed. Accordingly, as write to a memory cell in an overerased state can evenly be performed, influence by off-leakage is suppressed, and a memory cell having threshold voltage distribution with less variation can be implemented.

Abstract: A set of memory cells can be erased by individually erasing portions of the set in order to normalize the erase behavior of each memory cell and provide more consistent erase rates. An erase voltage pulse can be applied to the set of memory cells with a first group of cells biased for erase and a second group biased to inhibit erase. A second erase voltage pulse can then be applied with the second group biased for erase and the first group biased to inhibit erase. The groups are chosen so that the erase potentials for the cells in the first subset during the first pulse are about equal, so that the erase potentials for the cells in the second subset during the second pulse are about equal, and so that the erase potentials for the cells of the first subset are about the same as the erase potentials for the cells of the second subset.

Abstract: The present invention relates to a method for programming or erasing memory cells that include a selection transistor connected to a floating-gate transistor. According to the method, a non-zero compensation voltage is applied to the gate of a transistor not involved in the programming or erasing process so as to increase a breakdown threshold of the transistor, and an inhibition voltage is applied to the gate or to a terminal of at least one floating-gate transistor connected to the transistor having its breakdown threshold increased to inhibit a phenomenon of soft programming or soft erase of the floating-gate transistor.

Abstract: Charge trapping memory cells are protected from over-erasing in response to an erase command. For example, in response to an erase command, one bias arrangement is applied to program charge trapping memory cells, and another bias arrangement is applied to erase the charge trapping memory cells, such that the charge trapping memory cells have a higher net electron charge, in the erased state than i.n the programmed state. In another example, an integrated circuit with an array of charge trapping memory cells has logic which responds to an erase command by applying similar bias arrangements to the charge trapping memory cells. In a further example, such an integrated circuit is manufactured.

Abstract: A method for erasing a non-volatile memory device performs a block erase operation. The cells are then soft programmed and erase verified to determine if the threshold voltages indicate erased cells. A target cell is programmed to a first threshold voltage and verified. Adjacent cells are programmed and verified. The parasitic capacitance between the target cells and the adjacent cells causes the threshold voltage of the target cell to increase to a new threshold voltage with the programming of the adjacent cells. A difference between the new threshold voltage and the first threshold voltage is determined. If the difference is greater than or equal to a predetermined threshold, the target cell is soft programmed until the difference is less than the predetermined threshold.

Abstract: A hot count records the number of erase operations experienced by a block. The hot count is stored in an overhead data area of the block and is updated by circuits located on the same substrate as the block. Where a memory has two or more planes, each plane has circuits for updating hot counts.

Abstract: Embodiments of the present disclosure provide methods, devices, modules, and systems for healing non-volatile memory cells. One method includes biasing a first select gate transistor coupled to a string of memory cells at a first voltage, biasing a second select gate transistor coupled to the string at a second voltage, applying a first healing voltage to a first edge word line in order to extract charge accumulated between the first select gate transistor and a first edge memory cell stack of the string, and applying a second healing voltage to a second edge word line in order to extract charge accumulated between the second select gate transistor and a second edge memory cell stack of the string.

Abstract: A method of post-programming a flash memory device includes the steps of: post-programming memory cells of a selected word line in a predetermined unit; determining, after incrementing an address for selecting the next word line, whether the incremented address matches one of reference addresses; and varying the post-programming unit of the selected memory cells whenever the incremented address matches one of reference addresses.

Abstract: A method to eliminate over-erase in a nonvolatile trapped-charge memory array during write operations includes a three-cycle process of bulk programming the memory array, bulk erasing the memory array and selectively inhibiting one or more memory cells in the memory array while applying a programming voltage to the memory array.

Abstract: A dynamically variable source resistance is provided for each sector of a NOR-type Flash memory device. The variable source resistance of a given sector is set to a relatively low value (i.e., close to zero) during read operations. The variable source resistance is set to a relatively high impedance value (i.e., close to being an open circuit) during flash erase operations. The variable source resistance is set to a first intermediate resistance value at least during soft-programming where the first intermediate resistance value is one that raises VS and thus drives VGS below local threshold even for over-erased transistors of the sector that have a VGoff de-assertion voltage applied to their control gates for purpose of turning those transistors off. In one embodiment, the variable source resistance is set to a second intermediate resistance value during a testing mode that tests the extent to which the corresponding sector has been over-erased.

Abstract: A method is provided for testing and for preventing over-erasure of unused redundant memory cells that can be subsequently used to replace defective memory cells in a Flash memory. An unused redundant memory cell is preprogrammed and tested simultaneously with each group of n memory cells. The selected unused redundant memory cell is preprogrammed only a couple of times and then skipped for the rest of the preprogramming pulses applied to the regular core cells. Each unused redundant memory cells is selected g times, where g is the ratio between the number of regular core cells and the number of redundant core cells in a row. As soon as an unused redundant memory cell is successfully preprogrammed, further preprogramming of that unused redundant memory cell is stopped until all regular cells in the group are preprogrammed. An unused redundant memory cell remains available as a replacement cell until chip testing is completed.

Abstract: An apparatus and method for detecting an over-programming condition in a multistate memory cell. The invention is also directed to identifying the over-programmed cells and providing an alternate location at which to write the data intended for the over-programmed cell. An over-programmed state detection circuit generates an error signal when the data contained in a multistate memory cell is found to be over-programmed relative to its intended programming (threshold voltage level) state. Upon detection of an over-programmed cell, the programming operation of the memory system is modified to discontinue further programming attempts on the cell. The over-programmed state detection circuit is also used to assist in correcting for the over-programming state, permitting the programming error to be compensated for by the memory system.

Abstract: An electrically erasable charge trap nonvolatile memory cell has an initial threshold voltage, a program voltage that is higher than the initial threshold voltage, and an erase threshold voltage that is lower than the program threshold voltage but is higher than the initial threshold voltage. The programmed electrically erasable charge trap nonvolatile memory cells may be erased by applying an erase voltage for a time interval that is sufficient to lower the threshold voltage the transistor from a program threshold voltage to an erase threshold voltage that is lower than the program threshold voltage, but is higher than the initial threshold voltage. The time interval may be determined by repeatedly performing an endurance test using a time interval that is increased or decreased from an initial time interval, to obtain the time interval that meets an endurance specification, or allows a read to be performed successfully.

Abstract: A method for executing a write command for writing a binary word in a programmable memory, comprises writing each of the bits in a programmed state of a binary word to be written in a corresponding memory cell of the memory, reading each bit of the word written in the memory corresponding to a bit in the programmed state of the word to be written, comparing each bit in the programmed state of the word to be written with a corresponding bit read in the memory, and generating an error signal if at least one bit of the word to be written in the programmed state is different from the corresponding bit read. Application of the method can be particularly but not exclusively to integrated circuits for chip cards.

Abstract: A method is provided for programming a nonvolatile memory array including an array of memory cells, where each memory cell including a substrate, a control gate, a charge storage element, a source region and a drain region. The method includes receiving a programming window containing a predetermined number of bits that are to be programmed in the array and determining which of the predetermined number of bits are to be programmed in the memory array. The predetermined number of bits are simultaneously programmed to corresponding memory cells in the array. A programming state of the predetermined number of bits in the array is simultaneously verified.

Abstract: A semiconductor storage device comprises a semiconductor layer; a plurality of memory cells formed on the semiconductor layer, data writing, erasing or reading with respect to each of the memory cells being possible based on a voltage applied to a control electrode and a voltage applied to the semiconductor layer; a first booster circuit supplying a voltage to control electrodes of selected memory cells into which data is to be written; and a second booster circuit supplying a voltage to control electrodes of inhibited memory cells into which data is not to be written, wherein when erasing data in the memory cells, a potential at the semiconductor layer is boosted in a first boosting mode in which a boosting capability of the first booster circuit is low and a boosting capability of the second booster circuit is high, and then the potential at the semiconductor layer is boosted in a second boosting mode in which the boosting capability of the second booster circuit is low and the boosting capability of the fi

Abstract: An erase voltage generation circuit providing a uniform erase execution time and a non-volatile semiconductor memory device having the same, in which the erase voltage generation circuit includes a high voltage generation unit a voltage level detection unit, an execution time checking unit and a discharging unit. The high voltage generation unit generates an erase voltage. The voltage level detection unit detects the erase voltage and generates a level detection signal. The level detection signal is activated when the erase voltage reaches a target voltage. The execution time checking unit generates an execution end signal that is activated in response to the lapse of an erase execution time from the activation of the level detection signal. The discharging unit discharges the erase voltage as a discharge voltage. The high voltage generation unit is disabled in response to the activation of the execution end signal, and the discharging unit is enabled in response to the activation of the execution end signal.

Abstract: Methods of performing a sector erase of flash memory devices incorporating built-in self test circuitry are provided. The present invention employs an interactive verification and sector erase algorithm to verify and repeatedly erase the sector until a portion of the groups of each page of the sector are erased or a first maximum number of erase pulses is achieved. The algorithm further includes a word verification and erase operation that sequentially verifies and erases each word of the sector until each word is erased or a second maximum number of erase pulses is achieved. The second maximum number of erase pulses may be based on a function of the first maximum number of erase pulses. The second maximum number of erase pulses may be input to the sector erase algorithm as a multi-bit code. The second maximum number of erase pulses and conversion of the multi-bit code may be based on a binary multiple of the first maximum number of erase pulses.

Abstract: A set of non-volatile storage elements is divided into subsets for erasing in order to avoid over-erasing faster erasing storage elements. The entire set of elements is erased until a first subset of the set of elements is verified as erased. The first subset can include the faster erasing cells. Verifying the first subset includes excluding a second subset from verification. After the first subset is verified as erased, they are inhibited from erasing while the second subset is further erased. The set of elements is verified as erased when the second subset is verified as erased. Verifying that the set of elements is erased can include excluding the first subset from verification or verifying both the first and second subsets together. Different step sizes are used, depending on which subset is being erased and verified in order to more efficiently and accurately erase the set of elements.

Abstract: We describe a NAND flash memory device including a memory cell array formed on a substrate including a plurality of cell strings each including a string selecting transistor, a ground selecting transistor, and plural memory cells serially coupled between the string selecting transistor and the ground selecting transistor. A high voltage generator is configured to supply a bulk voltage to the substrate and an erase control circuit is configured to stepwise increase the bulk voltage during a first period of an erase operation and to maintain the bulk voltage substantially constant during a second period of the erase operation.

Abstract: A method and apparatus are provided for adaptive memory cell overerase compensation. A semiconductor memory device (100) is provided for performing the adaptively compensating erase verify operation (500, 600). The memory device (100) includes at least one word line (402). One or more memory cells (200) and one or more reference cells (406, 408) are connected to the word lines (402), where the one or more reference cells (406, 408) include an erased reference cell (408) connected to each word line (402). The method (500, 600) for adaptive memory cell overerase compensation includes determining an erase verify gate voltage (506, 608) utilizing the erased reference cell(s) (408) and verifying an erase voltage (514) of the memory cells (200) in response to the erase verify gate voltage (512, 614).

Abstract: A method for improving an over erasing effect of a charge-trapping memory cell. The charge-trapping memory cell has a transistor, which has a first terminal coupled to a first bit line and a second terminal coupled to a second bit line. First, the method erases the charge-trapping memory cell. Then, after the charge-trapping memory cell is completely erased, the first bit line is electrically connected to the second bit line to make a voltage level of the first bit line equal a voltage level of the second bit line such that the voltage level of the first terminal of the transistor equals the voltage level of the second terminal of the transistor.

Abstract: Erasing is performed with respect to a nonvolatile memory cell without causing depletion halfway therethrough. A control circuit for reversibly and variably controlling the threshold voltage of the nonvolatile memory cell by electrical erasing and writing controls an erase process of performing erasing to the plurality of nonvolatile memory cells assigned to one unit in an erase operation, a first write process of performing writing to the nonvolatile memory cell exceeding a pre-write-back level before a depletion level, and a second write process of performing writing to the nonvolatile memory cell exceeding a write-back level after the first write process. Since the occurrence of depletion is suppressed by successively performing the first write process with respect to the nonvolatile memory cells which may exceed the depletion level in the erase process, erasing can be performed to the nonvolatile memory cell without causing depletion halfway therethrough.

Abstract: One embodiment of the invention relates to a method for accessing a memory cell. In this method, at least one bit of the memory cell is erased. After erasing the at least one bit, a soft program operation is performed to bias the memory cell thereby improving the reliability of data stored in the memory cell. Other methods and systems are also disclosed.

Abstract: A method for preventing a memory from generating a leakage current is disclosed. The memory includes a boundary memory cell and a neighboring memory cell. The neighboring memory cell is adjacent to the boundary memory cell. The method includes the following step. The first terminal of the neighboring memory cell is connected to the second terminal through a metal line.