Abstract: A word line driver for flash memories using NMOS circuitry to reduce parasitic capacitance loading on boost circuitry in low-voltage applications. A delay scheme which delays turn-on of the driver's source-drain circuit for a short time after the turn-on of the driver transistors' gates allows the gate capacitance of the driver transistor to provide an extra boost.

Abstract: A non-volatile integrated circuit memory having an AND-like array structure that is capable of simultaneous reading and writing of digital data to multiple memory cells within the integrated circuit memory has memory cells within an array block of memory cells are arranged in columns and rows. A plurality of block bit lines is in communication with each array block of memory cells such that each block bit line interconnects the memory cells of one column of memory cells within one array block. A plurality of word lines is in communication with each array block of memory cells such that each word line interconnects the memory cells of one row within one array block. The integrated circuit memory further includes a plurality of global bit lines in communication with the array blocks to select a column of the array blocks and to transfer the digital data from and to the array blocks. A bit line selector selectively connects the plurality of global bit lines to the block bit lines.

Abstract: A memory cell selection scheme that permits simultaneous reading and writing of cells in different memory blocks by using separate routing for bias voltages to the cells. A read path and a program path are used to separately route the read and program voltages to a memory block. Separate read and program transistors are used to selectively route one of those two voltages to a regional voltage line, where individual local voltage transistors can selectively route voltage from the regional voltage line to local voltage lines. By placing a separate set of read and program transistors in each block, each block can be configured to conduct either read or program operations without regard to which of those functions is being performed in other blocks.

Abstract: The invention provides decoder circuits for selecting a word line in a semiconductor memory device which comprises a plurality of memory cell sectors including a plurality of word lines and bit lines and a plurality of memory cells which each is electrically erasable and programmable. The decoder circuits comprise a pull-up and pull-down transistors connected to global word lines which are connected to the word lines via connecting means, the decoder circuits turning on pull-down transistors before a high voltage according to an operation mode is supplied to one selected from the global word lines and pre-charging the gates of the pull-up transistors to the high voltage. The invention enables the decoder circuits to supply the word line drive voltage to the global word lines connected to memory cells by using the self-boosting method to thereby reduce the boosting load.

Abstract: A method of erasing a memory cell includes the step of erasing a memory cell. The current in the memory cell is measured. If the measured memory cell current approximately exceeds a predetermined level, the memory cell is soft programmed so if the memory cell is not overerased, the memory cell is undisturbed. The memory cell is soft programmed until the measured memory cell current is less than or equal to the predetermined level.

Abstract: There is provided a method of programming a non-volatile memory which can solve the problem of the data write system of the existing flash memory that a load capacitance of bit lines becomes large, the time required by the bit lines to reach the predetermined potential becomes longer, thereby the time required for data write operation becomes longer and power consumption also becomes large because the more the memory capacitance of memory array increases, the longer the length of bit lines becomes and the more the number of bit lines increases.

Abstract: A NOR-structured semiconductor memory device with a novel configuration of bit line connection is disclosed. The NOR-structured semiconductor memory device comprises a semiconductor memory cell array electrically connected to a plurality of bit lines. The plurality of bit lines are divided into at least four bit line groups. At least two bit lines of each bit line group are coupled to a main bit line through at least two bit line transistors, respectively. Furthermore, the bit lines of the NOR-structured semiconductor memory device are arranged in such a way that at least four adjacent bit lines thereof are selected from four different bit line groups and coupled to four different main bit lines, respectively. During a programming or data reading operation, two adjacent bit lines of the four adjacent bit lines are supplied with a programming voltage or sense current while the other two adjacent bit lines are grounded.

Abstract: A memory cell array 1 has the arrangement of a plurality of cores, each of which comprises one block or a set of a plurality of blocks, each block defining a range of memory cells serving as a unit of data erase. A core selecting part for selecting an optional number of cores to write/erase data is provided for writing data in memory cells in cores selected on the basis of a write command and for erasing data from selected blocks in cores selected on the basis of an erase command. Thus, there is realized a free core system capable of reading data out from memory cells in unselected cores while writing/erasing data in cores selected by the core selecting part.

Abstract: In erasing operation, a main bit line discharge signal CPO is set at a voltage of Vss so as for a main bit line discharge transistor CP to put a main bit line BL in a floating state. A substrate signal is set at Vds to charge a local bit line LBL to Vds. A drain select gate signal DSG is set at Vleg (<(Vds+Vth)) which makes a half-conducting state between the main bit line BL and the local bit line LBL. Thereby, the main bit line BL is charged to Vmbl (=Vleg−Vth(ST)) which lowers potential differences between a drain and a source of the select transistor ST and between a drain and a source of the main bit line discharge transistor CP.

Abstract: A nonvolatile semiconductor memory device includes a plurality of first wordlines, a plurality of second wordlines coupled to memory cells, the second wordlines being assigned to each of memory sectors, a plurality of transistors each of which connects a first wordline to a second wordline, and a circuit for controlling the transistors in common. One of the first wordlines is connected to one of the second wordlines through one of the transistors. A circuit area for decoding is reduced and current consumption is minimized.

Abstract: A flash memory array structure that has independently operating memory arrays. In one embodiment, a flash memory device comprises a poly silicon layer, a first metal layer and a second metal layer. The poly silicon layer has a plurality of word lines formed therein. The word lines are coupled to rows of memory cells. The first metal layer has a plurality of local bit lines formed therein. The local bit lines are coupled to columns of memory cells. The second metal layer has a plurality of global bit lines formed therein. The global bit lines are selectively coupled to the plurality of local bit lines. The global bit lines are further selectively bisected during manufacture to form a first bank and a second bank of memory cells. The first and second banks allow concurrent memory operations to be performed on the flash memory device.

Abstract: A semiconductor memory such as a flash memory, which comprises at least one two-dimensional array of memory cells with a plurality of rows and columns of memory cells grouped in a plurality of packets. The memory cells belonging to the columns of each packet are formed in a respective semiconductor region with a first type of conductivity, this region being distinct from the semiconductor regions with the first type of conductivity in which the memory cells belonging to the columns of the remaining packets are formed. The semiconductor regions with the first type of conductivity divide the set of memory cells belonging to each row into a plurality of subsets of memory cells that constitute elemental memory units which can be modified individually. Thus memory units of very small dimensions can be erased individually, without excessive overhead in terms of area.

Abstract: A nonvolatile semiconductor memory device includes a virtual-ground memory array which includes a plurality of nonvolatile memory cells and sub-bit lines connected to the nonvolatile memory cells, first and second selection lines, first and second selection transistors which become conductive in response to activation of the first selection line, a third selection transistor which become conductive in response to activation of the second selection line, a first main bit line which is coupled to and supplies a drain potential to a sub-bit line situated on a drain side of a selected memory cell through the first selection transistor, a second main bit line which is coupled to and supplies a source potential to a sub-bit line situated on a source side of the selected memory cell through one of the second selection transistor and the third selection transistor, and a third main bit line which is coupled to a sub-bit line adjacent to the sub-bit line situated on the drain side of the selected memory cell through a

Abstract: A circuit device structured to enable a hierarchic form of row decoding in semiconductor memory devices of the non-volatile type and including a matrix of memory cells with sectors organized into columns, wherein each sector has a group of local word lines individually connected to a main word line running through all of the matrix sectors which have rows in common is presented. The device includes a PMOS first transistor having conduction terminals connected respectively to the main word line and the local word line, an NMOS second transistor having conduction terminals connected respectively to the local word line and the main word line, and a PMOS third transistor having conduction terminals connected respectively to the main word line and the local word line. Such a third transistor is a charge transistor that reduces the charging time for the local word line.

Abstract: A semiconductor device has a memory cell array having the arrangement of a plurality of cores, each of which comprises one block or a set of a plurality of blocks, each block defining a range of memory cells serving as a unit of data erase. The semiconductor device has a bank setting memory circuit configured to select an optional number of cores of the cores as a first bank and to set the remaining cores as a second bank, so as to allow a data read operation to be carried out in one of the first and second banks while a data write or erase operation is carried out in the other of the first and second banks.

Abstract: Described herein is a nonvolatile memory comprising a memory array organized according to global word lines and local word lines; a global row decoder; a local row decoder; a first supply stage for supplying the global row decoder; and a second supply stage for supplying the local row decoder; and a third supply stage for biasing the drain and source terminals of the memory cells of the memory array. Each of the supply stages comprises a respective resistive divider formed by a plurality of series-connected resistors, and a plurality of pass-gate CMOS switches each connected in parallel to a respective resistor. The nonvolatile memory further comprises a control circuit for controlling the pass-gate CMOS switches of the supply stages, and a switching circuit for selectively connecting the supply input of the control circuit to the output of the second supply stage during reading and programming of the memory, and to the output of the third supply stage during erasing of the memory.

Abstract: A synchronous memory device which comprises global I/O lines for data input and output from and to a memory core and a pipeline latch circuit for latching data from the global I/O lines. The synchronous memory device includes a circuit that precharges the global I/O lines when a read command signal interrupts a write operation signal, and disables the pipeline latch circuit in order to prevent write data on the global I/O lines from being latched in the pipeline latch circuit. Accordingly, the write data is prevented from being transferred to the pipeline latch circuit at an early stage of the read operation.

Abstract: A structure to inspect high/low of memory cell threshold voltage using a current mode sense amplifier. A current mode sense amplifier is used to compare a memory cell current of a selected memory cell and a reference current to determine high/low of the threshold voltage. Since the current input is compared, it is not necessary to provide a reference word line and a reference memory cell circuit. The area is thus decreased, and the waiting time to convert current to voltage is saved to greatly increase the access speed.

Abstract: A memory device has been described that can read data stored in non-volatile memory cells using a differential voltage sensing technique. The memory includes a differential voltage sensing circuit having two input nodes. The nodes of the sensing circuit are pre-charged to different initial voltage levels prior to reading the memory cell. The nodes are pre-charged by charge sharing multiple bit lines during two charge sharing cycles. During a first cycle, both nodes are pre-charged to a common voltage level. During the second cycle, a reference node is further charge shared to reduce its voltage. A selected node that is coupled to a memory cell to be read is pre-charged to a higher value than the second sensing node. After a word line coupled to the memory cell is activated, the initial differential voltage between the sensing nodes will remain if the memory cell is programmed such that it does not conduct current in response to the word line signal.

Abstract: The present invention proposes a non-volatile semiconductor storage, comprising a plurality of main bit lines, a plurality of sub bit lines connected to the main bit lines, and a plurality of memory cell arrays, each including a plurality of non-volatile semiconductor memory cells disposed like an array. Each of those memory cells has a source terminal, a drain terminal, and a control gate, and each source-drain path is connected to a sub bit line. Between a main bit line and a sub bit line connected to the main bit line is disposed the source-drain path of a first transistor, and the source-drain path of a second transistor is connected to the sub bit line.

Abstract: A memory cell selection scheme that permits simultaneous reading and writing of cells in different memory blocks by using separate routing for bias voltages to the cells. A read path and a program path are used to separately route the read and program voltages to a memory block. Separate read and program transistors are used to selectively route one of those two voltages to a regional voltage line, where individual local voltage transistors can selectively route voltage from the regional voltage line to local voltage lines. By placing a separate set of read and program transistors in each block, each block can be configured to conduct either read or program operations without regard to which of those functions is being performed in other blocks.

Abstract: The optimized soft programming method is used in a memory consisting of a plurality of cells that are grouped into sectors. The cells that belong to a single sector have gate terminals connected to a plurality of word lines, and drain terminals connected to a plurality of local bit lines. The soft programming method consists of selecting at least one local bit line in the sector, and simultaneously selecting all the word lines in the same sector. A corresponding gate voltage is applied to all the word lines, whereas a constant drain voltage, with a pre-determined value is applied to the local bit line.

Abstract: A bank selector circuit for a simultaneous operation flash memory device with a flexible bank partition architecture comprises a memory boundary option, a bank selector encoder coupled to receive a memory partition indicator signal from the memory boundary option, and a bank selector decoder coupled to receive a bank selector code from the bank selector encoder. The decoder, upon receiving a memory address, outputs a bank selector output signal to point the memory address to either a lower memory bank or an upper memory bank in the simultaneous operation flash memory device, in dependence upon the selected memory partition boundary.

Abstract: A NOR-type flash memory device includes a global decoder circuit that is coupled to global wordlines. The global decoder circuit drives the global wordlines using wordline voltages that will be applied to local wordlines in each operation mode, and has wordline select switches each corresponding to the global wordlines. A local decoder circuit couples the local wordlines to the global wordlines in response to a sector select signal, and a sector generates a control signal in accordance with address information for selecting a memory cell array. A switch circuit includes a plurality of depletion MOS transistors each being coupled between corresponding first and second wordline. The depletion MOS transistors are commonly controlled by a control signal. Each of the wordline select switches is made of two NMOS transistors.

Abstract: A multilevel memory stores words formed by a plurality of binary subwords in a plurality of cells, each cell having has a respective threshold value. The cells are arranged on cell rows and columns, are grouped into sectors divided into sector blocks, and are selected via a global row decoder, a global column decoder, and a plurality of local row decoders, which simultaneously supply a ramp voltage to a biasing terminal of the selected cells. Threshold reading comparators are connected to the selected cells, and generate threshold attainment signals when the ramp voltage reaches the threshold value of the selected cells; switches, are arranged between the global word lines and local word lines, opening of the switches is individually controlled by the threshold attainment signals, thereby the local word lines are maintained at a the threshold voltage of the respective selected cell, after opening of the switches.

Abstract: The memory device has hierarchical sector decoding. A plurality of groups of supply lines is provided, one for each sector row, extending parallel to the sector rows. A plurality of switching stages are each connected between a respective sector and a respective group of supply lines; the switching stages connected to sectors arranged on a same column are controlled by same control signals supplied on control lines extending parallel to the columns of sectors. For biasing the sectors, modification voltages are sent to at least one selected group of biasing lines, and control signals are sent to the switching stages connected to a selected sector column.

Abstract: A simply structured, and highly reliable semiconductor apparatus having a large storage capacity. The apparatus has a plurality of memory cells on one semiconductor substrate, each including a capacitor having first and second electrodes, and a switching device having a control terminal connected to a corresponding word line among a plurality of word lines, and a current channel connected between the first electrode and a corresponding bit line among a plurality of bit lines. When the semiconductor apparatus is in a first mode, an OFF potential of the word lines is set to be a first potential, when the semiconductor apparatus is in a second mode, an OFF potential of the word lines is set to be a second potential, and a current channel of the switching device is set in a direction vertical to the semiconductor substrate.

Abstract: Data latch circuits are provided corresponding to select memory cells from or into which read or program is executed. The data latch circuits are grouped by two into sets. When 2-bit data is read from or programmed into the select memory cells, one data latch circuit is selected by a select signal, and, when 1-bit data is read or programmed, the two data latch circuits in one set are selected by a select signal. Between one or two selected data latch circuits and a data input/output buffer, data is exchanged. By so doing, changeover between 2-level data and multi-level (4-level or more-level) data concerning program or read of data into or out the memory cells becomes possible.

Abstract: A flash memory array arrangement having a plurality of erase blocks which can be separately erased. The erase blocks have separate source lines, the state of which is controlled by a source line decoder. In array read, program and erase operations, the source lines of the deselected erase blocks, the blocks that are not being read, programmed or erased, are set to a high impedance level. If a cell in one of the deselected erase blocks is defective in some respect such that the cell is conducting leakage current, the high impedance source line associated with the cell will reduce the likelihood that the defective cell will prevent proper operation of the selected erase block.

Abstract: A NOR type mask ROM includes a plurality of main bit lines formed in parallel with each other, a plurality of first sub-bit lines connected to the main bit lines through bit line contacts, a plurality of T-shaped second sub-bit lines each having a vertical arm formed in parallel with the main bit lines, and a horizontal arm formed in perpendicular with the vertical arm, and a plurality of third sub-bit lines each formed in parallel with the main bit lines and between vertical arms of two neighboring second sub-bit lines.

Abstract: A non-volatile memory device including a plurality of block, each including: a main bit line; a plurality of sub-bit lines to which memory transistors are connected and which are arranged in parallel with respect to the main bit line; and two cascade-connected selection gates which are provided between the main bit line and sub-bit lines and which selectively connect the sub-bit lines.

Abstract: A memory cell array 1 has the arrangement of a plurality of cores, each of which comprises one block or a set of a plurality of blocks, each block defining a range of memory cells serving as a unit of data erase. A core selecting part for selecting an optional number of cores to write/erase data is provided for writing data in memory cells in cores selected on the basis of a write command and for erasing data from selected blocks in cores selected on the basis of an erase command. Thus, there is realized a free core system capable of reading data out from memory cells in unselected cores while writing/erasing data in cores selected by the core selecting part.

Abstract: Method for localizing point defects causing column leakage currents in a non-volatile memory device including a plurality of memory cells arranged in rows and columns in a matrix structure, source diffusions, and metal lines which connect said source diffusions to each other. Such a method includes the steps of: modifying the memory device in order to make source diffusions independent of each other and each one electrically connected to a respective row; sequentially biasing the single columns of the matrix; localizing the column to which at least one defective cell belongs, as soon as the leakage current flow occurs in the biased column; by keeping biased the localized column, biasing sequentially the single rows of the matrix to the same potential as that of the localized column; localizing a couple of cells, wherein at least one of them involves the point defects, as soon as the leakage current flow does not occur.

Abstract: The invention provides decoder circuits for selecting a word line in a semiconductor memory device which comprises a plurality of memory cell sectors including a plurality of word lines and bit lines and a plurality of memory cells which each is electrically erasable and programmable. The decoder circuits comprise a pull-up and pull-down transistors connected to global word lines which are connected to the word lines via connecting means, the decoder circuits turning on pull-down transistors before a high voltage according to an operation mode is supplied to one selected from the global word lines and pre-charging the gates of the pull-up transistors to the high voltage. The invention enables the decoder circuits to supply the word line drive voltage to the global word lines connected to memory cells by using the self-boosting method to thereby reduce the boosting load.

Abstract: A select gate transistor has a select gate electrode composed of a first-level conductive layer and a second-level conductive layer. The first-level conductive layer has a plurality of contact areas. The second-level conductive layer has its portions removed that are located above the contact areas. Two adjacent select gate electrodes that are adjacent to each other in the column direction are arranged such that the contact areas of one select gate electrode are not opposed to the contact areas of the other select gate electrode. One select gate electrode has its first- and second-level conductive layers removed in their portions that are opposed to the contact areas of the other select gate electrode.

Abstract: The memory array comprises a plurality of cells, grouped together in sectors and arranged in sector rows and columns, and has both hierarchical row decoding and hierarchical column decoding. Global word lines are connected to at least two word lines in each sector, through local row decoders; global bit lines are connected to at least two local bit lines in each sector, through local column decoders. The global column decoder is arranged in the center of the memory array, and separates from each other an upper half and a lower half of the memory array. Sense amplifiers are also arranged in the middle of the array, thus saving space. This architecture also provides lesser stress of the cells, better reliability, and better production performance. In addition, each sector is completely disconnected from the remaining sectors, and only the faulty row or column of a single sector should be doubled.

Abstract: A circuit device structured to enable a hierarchic form of row decoding in semiconductor memory devices of the non-volatile type and including at least one matrix of memory cells with sectors organized into columns, wherein each sector has a specific group of local word lines individually connected to a main word line running through all of the matrix sectors which have rows in common is presented. The device includes a first transistor of the PMOS type having its conduction terminals connected, one to the main word line and the other to the local word line, and a second transistor of the NMOS type having its conduction terminals connected, one to the local word line and the other to a reference voltage.

Abstract: The present invention proposes a non-volatile semiconductor storage, comprising a plurality of main bit lines, a plurality of sub bit lines connected to the main bit lines, and a plurality of memory cell arrays, each including a plurality of non-volatile semiconductor memory cells disposed like an array. Each of those memory cells has a source terminal, a drain terminal, and a control gate, and each source-drain path is connected to a sub bit line. Between a main bit line and a sub bit line connected to the main bit line is disposed the source-drain path of a first transistor, and the source-drain path of a second transistor is connected to the sub bit line.

Abstract: To provide a semiconductor storage apparatus capable of reducing a chip area, one main bit line is provided to a plurality of sub bit lines commonly connected with drains of memory cell transistors, the plurality of the bit lines are connected to ends on one side of switches at a first stage, control terminals of which are respectively inputted with column selecting signals and ends on other side of the switches are commonly connected and connected to the main bit line via a switch at a second stage, a control terminal of which is inputted with a column selecting signal, the sub bit lines are wired to a first wiring layer, the main bit line is wired to a second wiring layer and the second wiring layer is wired with power source lines, lines of voltage control signals in erasing or writing and high voltage power supply lines in regions among the main bit lines.

Abstract: A memory architecture is disclosed that employs multiple column redundancies which provide multiple options for replacing a defective global odd or even bit line. Each column memory has two multiplexers, one for selecting a global odd bit line and another for selecting a global even bit line. Two or more column redundancies are coupled to each of the multiplexer in the column memory. In a first embodiment, the global odd and even bit lines are connected through odd and even sense amps in a regular column. In a second embodiment, the global odd bit line in a regular column connects through odd sense amps, while the global even bit line in the regular column connects through even sense amps. In a third embodiment, two or more sets of redundancy columns are commonly coupled to a left adjacent regular column and a right adjacent regular column.

Abstract: A memory device can read data stored in memory cells using a differential voltage sensing technique. The memory includes a differential voltage sensing circuit having two input nodes. The nodes of the sensing circuit are pre-charged prior to reading the memory cell. The nodes are pre-charged by charge sharing multiple bit lines. In one embodiment, local bit lines having a first charge are coupled to global bit lines having a second charge to provide a desired pre-charge level. The local and global bit lines can have equal capacitance values. The voltages of the bit lines prior to charge sharing can be any selected value, but in one embodiment the local bit lines are discharged to ground and the global bit lines are charged to Vcc. The memory includes a programmable fuse circuit to selectively activate pass circuitry and couple one or more local bit lines to a global bit line in response to the pass command code. This allows the pre-charge level of the sensing nodes to be adjusted after fabrication.

Abstract: The present invention proposes a non-volatile semiconductor storage, comprising a plurality of main bit lines, a plurality of sub bit lines connected to the main bit lines, and a plurality of memory cell arrays, each including a plurality of non-volatile semiconductor memory cells disposed like an array. Each of those memory cells has a source terminal, a drain terminal, and a control gate, and each source-drain path is connected to a sub bit line. Between a main bit line and a sub bit line connected to the main bit line is disposed the source-drain path of a first transistor, and the source-drain path of a second transistor is connected to the sub bit line.

Abstract: A non-volatile memory device is organized with memory cells that are arranged by row and by column. The memory device includes a sector of matrix cells, row decoders and column decoders suitable to decode address signals and to activate respectively the rows or said columns, at least a sector of redundancy cells such that it is possible to substitute a row of the sector of matrix cells with a row of the sector of redundancy cells. The non-volatile memory device comprises a local column decoder for the matrix sector and a local column decoder for the redundancy sector. The local column decoders are controlled by external signals so that the row of the redundancy sector is activated simultaneously with the row of the matrix sector.

Abstract: There is provided a storage method of a semiconductor storage apparatus provided with a source/drain area formed in a semiconductor substrate, a floating gate formed on a top layer of the area via a gate insulating film, and a control gate formed on the floating gate via an interlayer insulating film, the method comprising steps of: applying a predetermined positive voltage to a bit line connected to the drain area and a word line connected to the control gate, injecting an electron to the floating gate, and writing data to a selected memory cell; applying a predetermined negative voltage to a gate line, applying the predetermined positive voltage to a common source line connected to the semiconductor substrate or the source area, discharging the electron accumulated in the floating gate of the selected memory cell, and performing data erasing; and after the data erasing, applying the predetermined positive voltage necessary for injecting the electron to the floating gate from a channel area in the vicinity o

Abstract: A bank selector circuit for a simultaneous operation flash memory device with a flexible bank partition architecture comprises a memory boundary option 18, a bank selector encoder 2 coupled to receive a memory partition indicator signal from the memory boundary option 18, and a bank selector decoder 3 coupled to receive a bank selector code from the bank selector encoder 2. The decoder 3, upon receiving a memory address, outputs a bank selector output signal to point the memory address to either a lower memory bank or an upper memory bank in the simultaneous operation flash memory device, in dependence upon the selected memory partition boundary.

Abstract: A method of erasing a memory cell includes the step of erasing a memory cell. The current in the memory cell is measured. If the measured memory cell current approximately exceeds a predetermined level, the memory cell is soft programmed so if the memory cell is not overerased, the memory cell is undisturbed. The memory cell is soft programmed until the measured memory cell current is less than or equal to the predetermined level.

Abstract: Segmentation of FLASH Memory arrays allows the global and local bit lines to be isolated, greatly reducing global bit line capacitance, reducing bit line stress, and eliminating boot block disturb effects. Reduction in bit line capacitance also results in fast access time greatly improving the ability to implement larger arrays without paying severe access time penalties.

Abstract: A memory cell array is divided into a plurality of memory cell blocks each collectively subjected to an erasing operation as a unit. A P well regions for memory cell transistors and an N well region for electrically separating the P well regions are provided. Select transistors are formed in the same P well region as the memory cell transistor connected to the corresponding sub bit line of P well regions.

Abstract: A memory circuit that includes a series of parallel elongated diffusion bit lines and an array of 2-bit non-volatile memory cells connected between the diffusion bit lines. Column select circuits are located at the ends of the diffusion bits lines that selectively connect the diffusion bit lines to a bit line decoder circuit to read appropriate signals from selected memory cells. A series of metal jumpers extend over and connect the ends of the diffusion bit lines. By connecting both ends of the diffusion bit lines together, the metal jumpers allow the diffusion bit lines to be longer without increasing resistance, so that a single pair of column select circuit control a large number of memory cells to increase the area efficiency of the memory array. Conversely, the metal jumpers reduce the resistance in shorter diffusion bit lines, thereby increasing memory array endurance.

Abstract: A memory cell with a small surface area is fabricated by forming source lines and data lines above and below and by running the channels to face up and down. The local data lines for each vertically stacked memory cell are connected to a global data line by way of separate selection by a molecular oxide semiconductor, and use of a large surface area is avoided by making joint use of peripheral circuits such as global data lines and sensing amplifiers by performing read and write operations in a timed multiplex manner. Moreover, data lines in multi-layers and memory cells (floating electrode cell) which are non-destructive with respect to readout are utilized to allow placement of memory cells at all intersecting points of word lines and data lines while having a folded data line structure. An improved noise tolerance is attained by establishing a standard threshold voltage for identical dummy cells even in any of the read verify, write verify and erase verify operations.