Abstract: A method of erasing a sector of flash memory cells wherein a first set of preset pre-erase voltages is applied to the sector of flash memory cells. After the first set of preset pre-erase voltages is applied it is determined if another set of preset pre-erase voltages is to be applied to the sector of flash memory cells. If another set of preset pre-erase voltages is applied and if another set of preset pre-erase set of pre-erase voltages is not to be applied, a standard erase routine is applied to the sector.

Abstract: A method for providing a modified threshold voltage distribution for a dynamic reference array in a flash memory cell array. The dynamic reference array and an associated core memory cell array are programmed using two different programming processes to produce different Vt distributions for the dynamic reference array and the core memory cell array. The dynamic reference array is programmed using a finer program pulse to achieve a smaller distribution width, thus enhancing the read margin for the memory cell array. The finer pulse may be of shorter duration or of smaller amplitude. The finer programming process may be applied to one or more threshold voltage distributions (states) in the memory cell array.

Abstract: A flash memory array having multiple dual bit memory cells divided into section attached to a wordline and a pair of reference cells logically associated with each section. A method of reprogramming a section or sections of words that are required to be changed includes inputting allowed changes to the flash memory array, reading word or words to be changed in each section, programming bits in word or words to be changed in each section, refreshing previously programmed bits in the word or words that are changed, refreshing previously programmed bits in the word or words changed in each section, refreshing previously programmed bits in the remaining word or words in each section and refreshing previously programmed in each pair of reference cells in the section in which changes have been made.

Abstract: A sequential access memory structure includes an output bus and a plurality of sequential access memories, each of which is connected to the output bus. Each memory includes a memory array having a plurality of sequentially readable memory elements, a carry output for producing a carry signal when reading of the array has been substantially completed, and a carry input for causing reading of the array in response to a carry signal. The carry output of each memory is connected to a carry input of one other downstream memory respectively in a chain arrangement, and the carry signals cause the arrays to be read sequentially onto the output bus. Each memory further comprises a read-write storage connected between the array and the output bus, the storage including a plurality of sections. Data from the array is loaded into one section of the storage while data is being read from another section of the storage onto the output bus. The sections of memory elements in the array comprise half-pages.

Abstract: An array of memory cells includes a plurality of memory cells interconnected via a grid of M wordlines and M bitlines, wherein M=2, 3, 4, 5, . . . wherein each of the M bitlines is buried. The array further includes a plurality of contacts, wherein each of the plurality of contacts is formed every N wordlines, N=1, 2, 3, . . . , wherein each of the plurality of contacts overlies a gate of a different one of the plurality of memory cells. A strap connects one of the buried bitlines to a gate that underlies one of the plurality of contacts, and wherein contacts overlying a first bit line are staggered with respect to contacts overlying a second bit line that is adjacent to the first bit line.

Abstract: An non-volatile read only memory transistor for use in a memory array is disclosed. The non-volatile read only memory transistor features a substantially vertically oriented channel fabricated in a trench formed in the substrate. The channel length is dependent upon the depth of the trench and therefore a dense array of NROM transistors can be formed without adversely affecting the channel length and therefore the operational performance of the transistor.

Abstract: A method is provided to determine erase threshold voltages of memory transistors and thereby identify unusable memory transistors. A voltage is applied to the common source of a selected memory transistor and gradually incremented until a logical HIGH bit is read as a logical LOW bit. By iteratively incrementing Vbias, the erase threshold voltage for each memory transistor can be determined. In one process, the erase threshold voltage for each memory transistor in a memory device is determined and then the memory device is put under stress tests to simulate normal operative conditions. After the stress tests, the erase threshold voltage of each memory transistor can be once again determined to ascertain the change in the erase threshold voltage, i.e., the data retention characteristic, of each memory transistor.

Abstract: An array of memory cells that includes a plurality of memory cells interconnected via a grid of wordlines and bitlines, wherein each of the bitlines is buried. The array further includes a plurality of contacts, wherein each of the plurality of contacts is formed every N wordlines, N=1, 2, 3, . . . , and wherein each of the plurality of contacts overlies a gate of a different one of the plurality of memory cells. A strap connects one of the buried bitlines to a gate that underlies one of the plurality of contacts and wherein a column of the bitlines has a first discontinuous and a second discontinuous bitline that are separated from one another by a distance &Dgr;.

Abstract: A system is disclosed for producing an indication of the logical state of a flash memory cell for virtual ground flash memory operations. The system comprises a bit line precharge and hold circuit which is operable to apply and maintain a source terminal voltage (e.g., about 0 volts, ground) to a bit line associated with the source terminal of a cell adjacent to the cell which is sensed during a read operation, wherein the applied source terminal voltage is substantially the same as the bit line virtual ground voltage applied to the source terminal bit line of the selected memory cell to be sensed. The system also includes a drain bit line circuit operable to generate a drain terminal voltage for a drain terminal of a selected memory cell to be sensed.

Abstract: A memory device is disclosed having a memory cell in electrical communication with a node, and operative to indicate a binary value associated with data stored in the memory cell during a read operation when a first voltage is applied to the memory cell. The memory device includes a voltage booster connected between the node and a supply voltage which provides a boosted voltage to the node during the read operation, wherein the boosted voltage is greater than the supply voltage. A method is also disclosed for reading data stored in a memory cell, comprising applying a boosted voltage to a node in electrical communication with the memory cell, wherein the boosted voltage is greater that a supply voltage, and sensing a current associated with the memory cell in order to indicate a binary value associated with data stored in the memory cell during a read operation.

Abstract: A system is disclosed for producing an indication of the logical state of a flash memory cell for virtual ground flash memory operations. The system comprises a bit line charge and hold circuit which is operable to apply a read sense voltage (e.g., about 1.2 volts) to a bit line associated with the drain terminal of a cell of the flash array adjacent to the cell which is sensed, wherein the applied drain terminal voltage is substantially the same as the cell sense voltage (e.g., about 1.2 volts) applied to the drain terminal bit line of the selected memory cell to be sensed.

Abstract: A method for boosting potential in the channel of unselected memory cells on a selected bit-line. In this method, a first voltage is applied to all the word-lines of the memory cells in the string. A second voltage is then applied to word-lines adjacent the selected word lines to isolate the selected memory cell. Next, a programming voltage is applied to the selected word-line. In one embodiment, a time delay is applied between applying the second voltage and applying the third voltages to ensure isolation of the selected memory cell before applying the third voltage.

Abstract: A system is described for generating a charge pump voltage for flash memory operations, wherein a supply voltage detection circuit (e.g., analog to digital converter, digital thermometer) is configured to detect a supply voltage value and generate one or more supply voltage level detection signals associated therewith. The system further includes a charge pump circuit comprising one or more stages operable to receive a supply voltage and generate the charge pump output voltage having a value greater than the supply voltage, and a charge pump compensation circuit operably coupled to the supply voltage detection circuit and the charge pump circuit.

Abstract: A decoder for decoding from two sides of a memory array. The decoder is positioned on two sides of the memory array. The decoder includes driver circuits that are connected to routing lines from the memory array. To reduce the size of the decoder, some of the routing lines extend from one side of the memory array and the remaining routing lines extend from the other side of the memory array.

Abstract: A high voltage transistor exhibiting low leakage and low body effect is formed while avoiding an excessive number of costly masking steps. Embodiments include providing a field implant blocking mask over the channel area, thereby producing a transistor with low body effect, the field implant blocking mask having appropriate openings so that the field implant occurs at the edges of the channel, thereby reducing leakage.

Abstract: A method and system are disclosed for verifying memory cell erasure, which may be employed in association with a dual bit memory cell architecture. The method includes selectively verifying proper erasure of one of a first bit of the cell and a second bit of the cell, determining that the dual bit memory cell is properly erased if the first and second bits of the cell are properly erased, and selectively erasing at least one of the first and second bits of the cell if one of the first and second bits is not properly erased. The method may also comprise selectively re-verifying proper erasure of one of the first and second bits after selectively erasing at least one of the first and second bits.

Abstract: A voltage control circuit that programs or erases memory cells comprises an internal voltage value store, a register device selectively coupled to an external voltage value source or the internal voltage value store to receive a voltage value, a voltage output circuit coupled to the register device to receive the voltage value and to output a corresponding voltage to the memory cells, and a verify circuit determining the time to successfully program or erase the memory cells. The register device allows the memory cells to be programmed or erased with voltage values designated by the external voltage value source to determine programming and erasing characteristics of the memory cells. Voltage values producing acceptable programming and erasing characteristics are saved in the internal voltage value store.

Abstract: A programming control circuit programs a memory cell in accordance to a programming signal value that can be varied by a test equipment. The programming control circuit comprises a signal storage device, a signal output circuit, and a verification circuit. The signal storage device stores the programming signal value. The test equipment can be coupled to the signal storage device to write the programming signal value into the signal storage device. The signal output circuit is coupled to the signal storage device to receive the programming signal value. The signal output circuit converts the programming signal value into a programming signal and outputs the programming signal to the memory cell. The verification circuit determines whether the memory cell is successfully programmed. If the memory cell is not successfully programmed, the programming control circuit increases the programming signal value.

Abstract: Control circuitry and a method for generating an accurate drain voltage for selected memory core cells in a semiconductor memory device during a Read mode of operation is provided. Select gate transistors are provided which have their conduction path being coupled between a power supply voltage and a drain of one of the selected memory core cells. A differential amplifier circuit is responsive to a bitline voltage corresponding to a drain voltage of the selected memory core cells and a reference voltage for generating a select gate voltage. The select gate voltage is decreased when the bitline voltage is higher than a target voltage and is increased when the bitline voltage is lower than the target voltage. A source follower circuit is responsive to the select gate voltage for generating the bitline voltage which is maintained at the target voltage.

Abstract: Control circuitry and a method for generating an accurate boosted wordline voltage for selected memory core cells in a semiconductor memory device during a Read mode of operation is provided. Memory core transistors are provided which have their conduction path being coupled between a power supply voltage and a ground potential. Differential amplifier circuitry is responsive to a boost signal and a reference voltage for generating a select wordline voltage. The select wordline voltage is decreased when the wordline voltage is higher than a desired voltage and is increased when the wordline voltage is lower than the desired voltage. The control gates of the memory core transistors are responsive to the select wordline voltage.