摘要:
A method is disclosed for preventing over-erasure in a nonvolatile memory device having a plurality of sectors, each sector including a main field and a redundant field. The method includes the steps of programming memory cells included in the main and redundant fields, erasing the memory cells included in the main and redundant fields, and programming over-erased cells of the memory cells included in the main and redundant fields. The main and redundant fields are included in a sector.
摘要:
The flash memory device according to the present invention includes an erase control circuit, used as a state machine, having embodied erase algorithm which can prevent flash memory cells from being over-erased. The erase control circuit, first, checks whether or not threshold voltages of selected cells reach a predetermined pre-verify voltage higher than the maximum value of a target threshold voltage range corresponding to the erased state. When at least one of the selected cells has its threshold voltage higher than the pre-verify voltage, a high voltage generator generates a bulk voltage that is increased step by step by a predetermined voltage level. And, when the selected cells all have threshold voltages equal to or less than the pre-verify voltage, the high voltage generator generates a constant bulk voltage. According to this bulk voltage control scheme, the number of flash memory cells over-erased at the erase operation is reduced reducing the total erase time.
摘要:
An electrically erasable and programmable non-volatile semiconductor memory device and method of erasing the same device are provided. A fail bit counter is provided for the device and method. The fail bit counter counts erase fail bits during the sector erase operation. An erase control circuit selectively terminates the sector erase operation depending upon erase fail bit number.
摘要:
A flash memory device includes a plurality of memory cells each configured to store k-bit data, where k is a natural number greater than one. The device is programmed by a method including reading (i−1)-th order data from a selected memory cell connected to a selected wordline before programming i-th order data in one or more adjacent memory cells connected to an adjacent wordline, wherein i is a natural number between two and k, storing as read data the (i−1)-th order data read from the selected memory cell, and programming i-th order data in the selected memory cell based on the stored read data.
摘要:
Operation methods of charge-trap flash memory devices having an unused memory cell for data storage and a normal memory cell used for data storage are discussed. The operation method may include selecting the unused memory cell, and programming the unused memory cell to have a predetermined threshold voltage. The charge-trap flash memory device may thus be provided with improved reliability by interrupting erasure stress to unused memory cells.
摘要:
A method of programming a nonvolatile memory device is disclosed. The method includes providing a plurality of memory cells coupled to a wordline, the plurality of memory cells grouped into a plurality of groups, each group including at least two memory cells, such that for each cell of the plurality of memory cells that has memory cells adjacent both sides, the memory cells immediately adjacent either side of the cell belong to different groups from each other. The method further includes selecting one group from the plurality of groups, and performing a program operation including applying a program pulse to the selected group while one or more non-selected groups of the plurality of groups are inhibited from being programmed.
摘要:
Operation methods of charge-trap flash memory devices having an unused memory cell for data storage and a normal memory cell used for data storage are discussed. The operation method may include selecting the unused memory cell, and programming the unused memory cell to have a predetermined threshold voltage. The charge-trap flash memory device may thus be provided with improved reliability by interrupting erasure stress to unused memory cells.
摘要:
A flash memory device with an improved erase algorithm for erasing a plurality of memory cells that are arranged in intersections of wordlines and bitlines, respectively, includes an array of the memory cells. In the erase algorithm, all memory cells of the sector are erased at the same time. A pass/fail check & control logic then checks whether the memory cells are overerased. When one of a group of the erased memory cells is overerased, soft-program voltages are applied to the overerased memory cells such that the over-erased memory cells become soft-programmed. After boosting one of the soft-program voltages, the operations of checking, soft-programming, and boosting are carried out repeatedly, until a threshold voltage of the overerased memory cell moves within a target threshold voltage range of the erased memory cell. Therefore, overerasing is cured based upon program characteristics, without overcuring.
摘要:
A word line voltage supply circuit for a nonvolatile semiconductor memory device reduces power supply noise by deactivating a high voltage generator during a verify sensing operation. The word line voltage supply circuit includes a high voltage generator that produces a high voltage signal in response to a control signal from a controller. A voltage regulator regulates the high voltage signal to generate a verify voltage signal that is applied to a selected memory cell. The controller deactivates the control signal during a verify sensing operation so as to eliminate power supply noise caused by the pumping operation of the high voltage generator.
摘要:
The well regions of pumping units of charge pump circuits are maintained electrically floating. By maintaining the wells electrically floating, reduced impact from the body effect may be obtained. More specifically, integrated circuit charge pump circuits boost a first voltage from a voltage source to a second voltage at an output terminal. The charge pump circuits include a plurality of pumping units in an integrated circuit substrate of first conductivity type, that are serially connected between the voltage source and the output terminal. Each of the pumping units includes a well region of second conductivity type in the integrated circuit substrate of first conductivity type. The well region of second conductivity type is electrically floating. Each pumping unit also includes a transistor of the first conductivity type in the floating well region of second conductivity type, and a capacitor that is electrically connected to the transistor of the first conductivity type in the floating well region of second conductivity type.