Abstract: A memory is described which has memory cells that store data using hot electron injection. The data is erased through electron tunneling. The memory cells are described as floating gate transistors wherein the floating gate is fabricated using a conductive layer of nanocrystalline silicon particles. Each nanocrystalline silicon particle has a diameter of about 10 ? to 100 ?. The nanocrystalline silicon particles are in contact such that a charge stored on the floating gate is shared between the particles. The floating gate has a reduced electron affinity to allow for data erase operations using lower voltages.

Abstract: A compact dynamic random access memory (DRAM) cell and highly efficient methods for using the DRAM cell are disclosed. The DRAM cell provides reading, writing, and storage of a data bit on an ASIC chip. The DRAM cell includes a first transistor acting as a pass gate and having a first source node, a first gate node, and a first drain node. The DRAM cell also includes a second transistor acting as a storage device and having a second drain node that is electrically connected to the first drain node to form a storage node. The second transistor also includes a second source node and a second gate node. The second source node is electrically floating, thus increasing the effective storage capacitance of the storage node.

Abstract: Depletion-mode ferroelectric transistors are adapted for use as non-volatile memory cells. Various embodiments are described having a diode interposed between the bit line and a source/drain region of the transistor for added margin against read disturb. Various additional embodiments are described having an array architecture such that two memory cells sharing the same bit line also share the same program line. Using this configuration, non-selected cells are readily supplied with gate/source voltages sufficient to maintain the cells in a deactivated state during read and write operations on selected cells.

Abstract: A dielectric memory cell comprises a substrate which includes a source region, a drain region, and a channel region positioned there between. A multilevel charge trapping dielectric is positioned on the surface of the substrate and a control gate is positioned on the surface of the dielectric and is positioned over and aligned with the channel region. The multilevel charge trapping dielectric includes a tunneling dielectric layer, a charge trapping dielectric layer, and a top dielectric layer. The tunneling dielectric layer comprises a first dielectric material having a wide band gap between a tunneling dielectric layer valance band Fermi level and a tunneling dielectric layer conduction band Fermi level. The top dielectric layer comprises a second dielectric material having a valance band Fermi level approximately equal to the tunneling dielectric layer valance band Fermi level and having a conduction band Fermi level greater than the tunneling dielectric layer conduction band Fermi level.

Abstract: A non volatile memory includes a plurality of transistors having a non conductive storage medium. The transistors are erased by injecting holes into the storage medium from both the source edge region and drain edge region of the transistor. In one example, the storage medium is made from silicon nitride isolated from the underlying substrate and overlying gate by silicon dioxide. The injection of holes in the storage medium generates two hole distributions having overlapping portions. The combined distribution of the overlapping portions is above at least a level of the highest concentration of program charge in the overlap region of the storage medium. In one example, the transistors are programmed by hot carrier injection. In some examples, the sources of groups of transistors of the memory are decoded.

Abstract: A method of programming a flash memory through boosting a voltage level of a source line. The flash memory has n memory cell transistors cascaded in series, a local bit line positioned above the n memory cell transistors, a buried bit line positioned under the n memory cell transistors, and a source line positioned under the buried bit line. The method includes inputting a word line voltage to a control gate of a kth memory cell transistor, and after floating the local bit line, inputting a source line voltage to the source line for inducing an FN tunneling effect inside the kth memory cell transistor through capacitance coupling between the buried bit line and the source line.

Abstract: For particularly flexible and space-saving information storage, a charge trapping memory cell and a corresponding semiconductor memory device include a charge trapping gate configuration provided with a plurality of charge trapping gates each configured for substantially independent information storage. As a result, a plurality of information units can be stored independently of one another in the memory cell. Also provided is a method for producing such a memory cell.

Abstract: A flash NAND type EEPROM system with individual ones of an array of charge storage elements, such as floating gates, being capacitively coupled with at least two control gate lines. The control gate lines are preferably positioned between floating gates to be coupled with sidewalls of floating gates. The memory cell coupling ratio is desirably increased, as a result. Both control gate lines on opposite sides of a selected row of floating gates are usually raised to the same voltage while the second control gate lines coupled to unselected rows of floating gates immediately adjacent and on opposite sides of the selected row are kept low. The control gate lines can also be capacitively coupled with the substrate in order to selectively raise its voltage in the region of selected floating gates. The length of the floating gates and the thicknesses of the control gate lines can be made less than the minimum resolution element of the process by forming an etch mask of spacers.

Abstract: A DMOS device is provided which is equipped with a floating gate having a first and second electrode in close proximity thereto. The floating gate is separated from one of the first and second electrodes by a thin layer of dielectric material whose dimensions and composition permit charge carriers to tunnel through the dielectric layer either to or from the floating gate. This tunneling phenomenon can be used to create a threshold voltage that may be adjusted to provide a precise current by placing a voltage between a programming electrode and the body/source and gate electrode of the device.

Abstract: A non-volatile memory device includes floating gate memory cells, a pulse counter and voltage pump control circuitry. The control circuitry selectively activates pumps in response to a count output of the counter. In one embodiment, the pump output current is increased as the counter output increases. The memory allows for erase operations that reduce leakage current during initiation of an erase operation.

Abstract: A transistor structure having a dedicated erase gate where the transistor can be used as a memory cell is disclosed. The presently preferred embodiment of the transistor comprises a floating gate disposed on a substrate and having a control gate and an erase gate overlapping said floating gate, with drain and source regions doped on the substrate. By providing a dedicated erase gate, the gate oxide underneath the control gate can be made thinner and can have a thickness that is conducive to the scaling of the transistor. The overall cell size of the transistor remains the same and the program and read operation can remain the same. Both the common source and buried bitline architecture can be used, namely twin well or triple well architectures. A memory circuit using the transistors of the present invention is disclosed as well for flash memory circuit applications.

Abstract: A method of erasing a non-volatile semiconductor memory device comprising, to raise the convergence of the erasure voltage, performing a write-erase operation, at least one write-erase operation after erasure, or a plurality of write-erase operations as an operation when erasing a memory transistor including dispersed charge storing means in a gate insulating film interposed between a channel-forming region of the semiconductor and a gate electrode and, to increase the erasure speed, optimizing an erasure voltage and/or an erasure time in accordance with the phenomenon of the absolute value of a voltage of an inflection point taking an extremum at the erasing side in a hysteresis curve shown the change of threshold voltage with respect to an applied voltage of the memory transistor becoming larger along with a shortening of a voltage application time.

Abstract: A method and apparatus for setting a floating gate in a floating gate circuit using dual conduction of Fowler-Nordheim tunnel devices is disclosed. In one embodiment, the present invention comprises a floating gate circuit having a single floating gate. During a set mode, the charge level on the floating gate is modified until it is set to a predetermined charge level that is a function of an input set voltage. In another embodiment, the floating gate circuit comprises two floating gates. During a set mode the charge level on each of the floating gates is modified until the difference in charge level between the two floating gates is a predetermined function of an input set voltage that is capacitively coupled to one of the floating gates during the set mode.

Abstract: A semiconductor memory device is provided with a memory cell, at least one select gate transistor and a circuit. The circuit is configured to rewrite data in the memory cell by applying a potential difference between the gate and the source or between the gate and the drain, which is larger than a power supply voltage. The circuit operates in a first data programming mode and a second data programming mode. A first command or a first combination is used for the first data programming mode. A second command or a second command combination is used for the second data programming mode. The source line is set to different potentials between the first data programming mode and the second data programming mode, in a period when data is rewritten, by using the different command or the different command combination.

Abstract: Fuse circuits based on a single flash cell or floating-gate memory cell are adapted for use in memory devices, particularly in low-voltage, flash memory applications. The fuse circuits include a floating-gate memory cell for storing a data value and a fuse latch to hold and transfer the data value of the floating-gate memory cell at power-up or upon request. A latch driver circuit can write data values to the fuse latch without affecting the data value stored in the floating-gate memory cell. The fuse circuits can further utilize the same structure, pitch, bit-line organization and word-line organization as the memory device's memory array. As the fuse circuits can utilize the same structure and organization, the data value of the fuse circuit can be programmed, erased and read using the same data path as the regular memory array.

Abstract: An extraction method and an integrated cell for extracting a binary value based on a propagation of an edge of a triggering signal in two electric paths, including across two voltage supply terminals: two parallel branches each including, in series, a resistor for differentiating the electric paths; a read transistor, the junction point of the resistor and of the read transistor of each branch defining an output terminal of the cell, and the gate of the read transistor of each branch being connected to the output terminal of the other branch; and a selection transistor.

Abstract: A reference cell transistor with a series resistance to improve reliability in reading cells in an associated memory array. The reference cell transistor is coupled in series with a resistive element such that a reference current flows therethrough to reduce a voltage between a gate and a source of the reference cell transistor. This bends the Ids versus Vgate curve of the reference cell downward and compensates for irregularities in the resistance seen in series with the memory cell transistors. In this fashion, the margin when reading memory cells is improved and the reference current is more reliable. The resistive element may be external to a region having the reference cell transistor. Alternatively, the resistive element may be internal to a region with the memory array and reference cell. For example, it may be formed by extending the source region of the reference cell transistor.

Abstract: A method for sensing the voltage on a floating gate in a floating gate circuit during a set mode is disclosed.

Abstract: The present invention relates to a non-volatile semiconductor memory device and a fabricating method thereof, which prevents a programming disturbance and enables to have a programming operated by a byte unit by achieving a programming and an erasing of a memory device through a F-N tunneling.

Abstract: A method of a read scheme for a non-volatile memory cell. The non-volatile memory cell includes a substrate, a source, a drain and a gate above a channel separated by a nonconducting charge trapping material sandwiched between first and second insulating layers. The method applies a first positive drain-to-source bias, a second positive source-to-substrate bias, and a third positive gate-to-source bias to read the source-side charges trapped in the trapping material near the source side.

Abstract: A semiconductor integrated circuit includes non-volatile memory elements (PM1, PM2), each of which has a first source electrode, a first drain electrode, a floating gate electrode and a control gate electrode and is capable of having different threshold voltages, and read transistor elements (DM1, DM2), each of which has a second source electrode and a second drain electrode and is capable of having different mutual conductances according to the threshold voltage of the non-volatile memory element. The read transistor element has a switching state according to the electron injection state or the electron emission state, in other words, the writing state or the erasing state of the floating gate electrode. In a read operation, it is not necessary to cause a channel current to flow according to the threshold voltage of the non-volatile memory element.

Abstract: A semiconductor memory device includes a memory cell array having a plurality of memory cells, and each of the memory cells includes a first MISFET and a second MISFET. The first MISFET includes a first source region, a first drain region and a first gate electrode, and a semiconductor layer between the first source region and the first drain region is a floating body in a floating state. The second MISFET includes a second source region, a second drain region and a second gate electrode, and the semiconductor layer between the second source region and the second drain region is the floating body shared with the first MISFET.

Abstract: Structures and methods for DEAPROM memory with low tunnel barrier intergate insulators are provided. The DEAPROM memory includes a first source/drain region and a second source/drain region separated by a channel region in a substrate. A floating gate opposes the channel region and is separated therefrom by a gate oxide. A control gate opposes the floating gate. The control gate is separated from the floating gate by a low tunnel barrier intergate insulator having a tunnel barrier of less than 1.5 eV. The low tunnel barrier intergate insulator includes a metal oxide insulator selected from the group consisting of NiO, Al2O3, Ta2O5, TiO2, ZrO2, Nb2O5, Y2O3, Gd2O3, SrBi2Ta2O3, SrTiO3, PbTiO3, and PbZrO3. The floating gate includes a polysilicon floating gate having a metal layer formed thereon in contact with the low tunnel barrier intergate insulator. And, the control gate includes a polysilicon control gate having a metal layer formed thereon in contact with the low tunnel barrier intergate insulator.

Abstract: Provided is a nonvolatile memory that realizes a high-speed verify operation. During verify writing/erasing, the writing/erasing and reading are performed at the same time. As to a circuit that performs a verify operation, for instance, there is obtained a construction where the output from a sense amplifier (102) that performs reading is connected to a switch which switches and operation voltage applied to a memory cell in accordance with a verify signal Sv, and the verify operation is finished concurrently with having the verifying signal Sv switched. By obtaining such circuit construction and simultaneously performing writing/erasing and reading, it becomes possible to perform high-speed verify writing/erasing.

Abstract: A nonvolatile memory array can be erased by sectors, or alternatively a chip erase operation can be performed to erase all the cells of the array in parallel.

Abstract: The present invention describes a two transistor flash EEPROM memory cell which has a symmetrical source and drain structure, which permits the cell size not limited by program and erase operations. The memory cell comprises an NMOS floating gate transistor forming a nonvolatile storage device and an NMOS transistor forming an access device. The floating gate transistor is programmed and erased using Fowler-Nordheim channel tunneling. The two transistor memory cell is used in a memory array of columns and rows where a column of cells is coupled by a bit line and a source line, and where a row of cells is coupled by a word line and an access line. The memory array is highly scalable and is targeted for low-voltage, high-speed and high-density programmable logic devices.

Abstract: A method for operating a non-volatile memory device, which is applicable to an n-channel non-volatile memory device, wherein a positive voltage is applied to the control gate, a negative voltage is applied to the drain region while the source region is floating. Furthermore, a negative voltage is applied to the substrate to program to the n-channel memory device by the channel Fowler-Nordheim tunneling effect. To erase the n-channel non-volatile memory device, a negative voltage is applied to the control gate, a positive voltage is applied to the drain region, and the source region is floating. Moreover, a positive voltage is applied to the substrate to erase the n-channel memory device using the channel Fowler-Nordheim tunneling effect.

Abstract: Structures and methods for memory cells having a volatile and a non-volatile component in a single memory cell are provided. The memory cell includes a first source/drain region and a second source/drain region separated by a channel region in a substrate. A storage capacitor is coupled to one of the first and the second source/drain regions. A floating gate opposes the channel region and separated therefrom by a gate oxide. A control gate opposes the floating gate. The control gate is separated from the floating gate by a low tunnel barrier intergate insulator. The memory cell is adapted to operate in a first and a second mode of operation. The first mode of operation is a dynamic mode of operation and the second mode of operation is a repressed memory mode of operation.

Abstract: This inventing is intended to shorten data deletion time of a nonvolatile semiconductor memory such as a flash memory (EEPROM). When deleting data written to a memory cell MC0 among flash memory cells MC0 to MC2 formed on a semiconductor substrate PSUB through a separation region NiSO, a voltage of p type well PWL0 in which the memory cell MC0 is formed is raised to 10V and a voltage of the separation region NiSO is raised to 12V by using a voltage application unit different from a voltage application unit applying a voltage to the p type well PWL0. As a result, parasitic capacitances Ca1 and Ca2 generated between p type wells PWL1 and PWL2 in which the unselected memory cells MC1 and MC2 are formed and the separation region NiSO, respectively, and a parasitic capacitance Cb generated between the separation region NiSO and the semiconductor substrate PSUB are charged by the voltage application units.

Abstract: A memory circuit for programming a target cell is disclosed. According to one embodiment, the memory circuit comprises the target cell having a drain terminal connected to a bit line. A drain voltage is coupled to the bit line and supplies a voltage greater than a ground voltage, while a gate voltage is coupled to a gate terminal of the target cell and supplies a voltage greater the ground voltage. A source voltage is coupled to a source terminal of the target cell and supplies a voltage less than the ground voltage, and a substrate voltage is coupled to a substrate of the target cell and supplies a voltage less than the ground voltage.

Abstract: A dual bit dielectric memory cell comprises a substrate with a source region and a drain region implanted on opposing sides of a central channel region. A multilevel charge trapping dielectric is positioned on the substrate above the central channel region and includes a central region between an opposing source lateral region and a drain lateral region. A control gate is positioned above the multilevel charge trapping dielectric. The multilevel charge trapping dielectric comprises a tunnel dielectric layer adjacent the substrate, a top dielectric adjacent the control gate, and a charge trapping dielectric positioned there between. The thickness of the tunnel dielectric layer in the central region is greater than a thickness of the tunnel dielectric layer in each of the source lateral region and the drain lateral region.

Abstract: A non-volatile memory device includes a semiconductor substrate having first and second bitlines buried therein. The first bitline serves as a source terminal and the second bitline serves as a drain terminal. An oxide-nitride-oxide (ONO) stack is formed over the substrate. The ONO stack includes a charge storing layer having at least four charge storing cells therein. A pair of complementary conductive regions are disposed on opposite sides of the ONO stack extending in a direction perpendicular to the first and second bitlines. A wordline, which serves as a gate electrode, is disposed above the ONO stack and laterally between the first and second complementary conductive regions.

Abstract: An EEPROM memory cell comprising a transistor on a first conductivity type semiconductor substrate and a capacitor formed on a second conductivity type semiconductor substrate. The capacitor comprises first and second injector regions of third conductivity type, a channel region of second conductivity type separating the first and second injector regions and a first electrically floating structure disposed above the channel region, wherein a first edge portion of the floating structure overlaps a portion of the first injector region and a second edge portion of the first floating structure overlaps a portion of the second injector region, and a control gate region of fourth conductivity type located within the second conductivity type semiconductor substrate region. The gate structure and first floating structure are electrically connected together. In different aspects of the present invention, the EEPROM memory cell may also include a second capacitor.

Abstract: Silicon carbide films are grown by carburization of silicon to form insulative films. In one embodiment, the film is used to provide a gate insulator for a field effect transistor. The film is grown in a microwave-plasma-enhanced chemical vapor deposition (MPECVD) system. A silicon substrate is first etched in dilute HF solution and rinsed. The substrate is then placed in a reactor chamber of the MPECVD system in hydrogen along with a carbon containing gas. The substrate is then inserted into a microwave generated plasma for a desired time to grow the film. The microwave power varies depending on substrate size. The growth of the film may be continued following formation of an initial film via the above process by using a standard CVD deposition of amorphous SiC. The film may be used to form gate insulators for FET transistors in DRAM devices and flash type memories. It may be formed as dielectric layers in capacitors in the same manner.

Abstract: A convergence signal includes a series of voltage pulses used to perform a convergence procedure in one or more flash EEPROM memory cells (transistors). In one instance subsequent voltage pulses in the convergence signal each have a higher voltage than the preceding pulse. In another instance, subsequent voltage pulses in the convergence signal each have a longer duration than the preceding pulse. An integrated circuit includes an array of memory cells and an erase control unit which controls the application of the convergence signal to one or more memory cells. The integrated circuit may be either serial or parallel flash EEPROM in which bulk, sector, or page mode erasing is used.

Abstract: Floating-gate memory cells having a trench source-line contact are suited for increased packing densities without a need for low-resistance ground straps placed at regular intervals across a memory array. Such floating-gate memory cells have their drain regions and source regions formed in a first semiconductor region having a first conductivity type. This first semiconductor region is separated from the underlying substrate by an interposing second semiconductor region having a second conductivity type different from the first conductivity type. The source regions of the memory cells are coupled to the second semiconductor region as a common source line. Such memory cells can be programmed, read and erased by applying various potential levels to their control gates, their drain regions, the first semiconductor region, and the second semiconductor region.

Abstract: A method of fabricating a multi-bit flash memory, having a control gate, a floating gate, a source region, a drain region and a channel region. An isolation region is formed in the floating gate to partition the floating gate into a plurality of conductive blocks. The conductive blocks are arranged in an array with rows extending from the source region to the drain region. Each row of the array has two conductive blocks. Before any data is written to the flash memory, the channel regions under the conductive blocks of the same row have the same threshold voltage, while the channel regions under the conductive blocks of different rows have different threshold voltage.

Abstract: A nonvolatile semiconductor memory device with high reliability (free from troubles in storing data), a high charge injection efficiency, and enabling parallel operation in a VG cell array, includes channel forming regions, a charge storing film which consists of stacked dielectric films and is capable of storing a charge, two storage portions forming parts of the charge storing film and overlapping the channel forming regions, a single layer dielectric film between the storage portions and in contact with the channel forming region, a control gate electrode on the single layer dielectric film, and a memory gate electrode on the storage portions.

Abstract: A ferroelectric memory devices including a reference programming portion for regulating and outputting voltages of reference level control signals by using a programmable register, which programs the level of output signal with externally applied signals and maintains the program results without power, to control on/off of switches regulating capacitance of capacitors connected to driving power; and a reference voltage generating portion for outputting a reference voltage according to the reference level control signal. A method for programming the ferroelectric memory device is also disclosed which includes the steps of: decoding a signal inputted in a signal input unit; activating a program mode operating signal corresponding to the program mode and deactivating the signal input unit; and performing the program mode in response to the program mode operating signal.

Abstract: In a semiconductor integrated circuit device including a third gate, the present invention improves miniaturization and operation speed and reduces a defect density of an insulator film. In a semiconductor integrated circuit device including a well of a first conductivity type formed in a semiconductor substrate, a source/drain diffusion layer of a second conductivity type inside the well, a floating gate formed over the semiconductor substrate through an insulator film, a control gate formed and isolated from the floating gate through an insulator film, word lines formed by connecting the control gates and a third gate formed and isolated from the semiconductor substrate, the floating gate and the control gate through an insulator film and different from the floating gate and the control gate, the third gate is buried into a space of the floating gates existing in a direction vertical to the word line and a channel.

Abstract: In a nonvolatile semiconductor memory provided with a plurality of memory elements each having a control gate and a floating gate, an electric current detecting circuit detects a drain current supplied to a drain of each of the memory elements and a voltage control circuit controls, in accordance with the drain current detected by the electric current detecting circuit, a control gate voltage supplied to the control gate of each of the memory elements.

Abstract: In a non-volatile memory, the source potential of a selected cell transistor to be programmed is controlled to be changed in accordance with a distance between a program voltage generator connected to a bit line and to the selected cell transistor. When the distance between the selected cell transistor and the program voltage generator is a first distance, the source potential at the selected cell transistor is controlled to be a first potential, and when the distance between them is a second distance longer than the first distance, the source potential at the selected cell transistor is controlled to be a second potential higher than the first potential. As a result, the drain-source voltage at the selected cell transistor to be programmed can be optimized, and optimization of the programming can be implemented.

Abstract: An erasing method for a p-channel nitride read only memory. The method is used for a p-channel nitride read only memory having charges stored in a charge-trapping layer. A positive voltage is applied to the control gate and a negative voltage to the drain; also, the source is floating and the n-well is grounded. The voltage difference between the positive voltage applied to the control gate and the negative voltage to the drain is sufficient to trigger a band-to-band induced hot electron injection to erase the p-channel nitride read only memory.

Abstract: A compact dynamic random access memory (DRAM) cell and highly efficient methods for using the DRAM cell are disclosed. The DRAM cell provides reading, writing, and storage of a data bit on an ASIC chip. The DRAM cell includes a first transistor acting as a pass gate and having a first source node, a first gate node, and a first drain node. The DRAM cell also includes a second transistor acting as a storage device and having a second drain node that is electrically connected to the first drain node to form a storage node. The second transistor also includes a second source node and a second gate node. The second source node is electrically floating, thus increasing the effective storage capacitance of the storage node.

Abstract: Disclosed is a method and apparatus for evaluating margin voltages in single poly EEPROM cells. Briefly, the invention involves shifting the cell's threshold voltage higher, resulting in a corresponding rise in the margin voltage, so that testing for the erase margin may be conducted in the positive voltage range. The present invention implements a variety of solutions to the problem, including both innovations in cell processing and circuitry. In one embodiment, the process steps employed to create the floating gate transistor are changed in order to increase its threshold voltage. Alternatively, or in combination with these general process changes, the width of the floating gate transistor may be reduced, resulting in a corresponding increase in the margin voltage.

Abstract: A non-volatile memory is described, which comprises a plurality of memory cells, a plurality of word lines, a plurality of drain lines and a plurality of source lines. Two adjacent memory cells in the same row share a source and are grouped into a cell pair, and all of the cell pairs are arranged in rows and columns, wherein two cell pairs in the same row share a drain. The sources of the memory cells in the same row are connected to a source line, and the drains of the memory cells in the same row are connected to a drain line. The gates of the memory cells in the same column are coupled to a word line.

Abstract: A memory array includes a plurality of sets of transistors, each set including a pair of transistors in series. Each such pair of transistors is connected between a pair of adjacent bit lines. Each of the pair of transistors in each set is associated with a different one of an adjacent pair of word lines. The array is configured by providing substantially strait elongated source/drain regions in side-by-side, parallel relation. Each bit line has a zigzag configuration and connects to a pair of adjacent source/drain regions in alternating manner along the bit line length.

Abstract: A method for use in erasing data stored in a memory cell includes asserting a voltage differential across a tank region and a gate region of the memory cell, wherein the tank region has a first conductivity type and the tank region is located within a well region of a second conductivity type. The method also includes floating the voltage level of a source region and a drain region of the memory cell, wherein the source region and the drain region are located within the tank region and have the second conductivity type. The method additionally includes discharging a charge stored in the drain region by electrically connecting the source region to an electric potential lower than the potential of the drain region and electrically connecting the well region and the tank region to a potential lower than their existing potentials.

Abstract: A control signal MBPRG is inputted to individual block decoders that constitute a block decoder section 37 of an ACT type flash memory. Then, the level of the control signal MBPRG is set to “H” to select all the blocks regardless of the contents of address signals a5 through a13, and one word line WL is selected from all the blocks by the addresses a0 through a4. By thus selecting one word line WL every block that is electrically separated by the select transistor and simultaneously applying a write voltage during the test to the same number of word lines WL as the number of blocks, the possible occurrence of a bad influence exerted on the other memory cells is prevented even when the memory cells in which a write operation during the test has been executed include a memory cell that has a negative threshold voltage.

Abstract: A method for operating a memory cell of a multi-level NROM is described. The memory cell of the multi-level NROM comprises a nitride layer, wherein the nitride layer comprises a plurality of charge-trapping regions to store locally a plurality of charges as the first bit memory and the second bit of memory. The stored charges of the second bit of memory forms an electrical barrier, which in turns affects the size of the threshold electric current of the first bit. The different threshold electrical currents of the first bit, which are affected by the size of the electrical barrier, define the various memory states of the memory cell of the multi-level NROM.