摘要:
An EEPROM includes an array of memory cell transistors, which is divided into cell blocks each including NAND cell units of series-connected cell transistors. A sense amplifier is connected to bit lines and a comparator. A data-latch circuit is connected to the comparator, for latching a write-data supplied from a data input buffer. After desired cell transistors selected for programming in a selected block are once programmed, a write-verify operation is performed. The comparator compares the actual data read from one of the programmed cell transistors with the write-data, to verify its written state. The write-verify process checks the resulting threshold voltage for variations using first and second reference voltages defining the lower-limit and upper-limit of an allowable variation range. If the comparison results under employment of the first voltage shows that an irregularly written cell transistor remains with an insufficient threshold voltage which is so low as to fail to fall within the range, the write operation continues for the same cell transistor. If the comparison results under employment of the second voltage shows that an excess-written cell transistor remains, the block is rendered "protected" at least partially.
摘要:
An EEPROM for storing multi-level data includes a memory cell array in which electrically erasable and programmable memory cells are arranged in matrix and each of the memory cells has at least three storage states, a write circuit for writing data to the memory cells, first and second write verify means each constituted of a sense amplifier, a data latch circuit and a detection circuit, for verifying an insufficient-written state of a memory cell and an excess-written state of a memory cell, respectively, an additional write circuit for additionally writing data to the memory cell in the insufficient-written state, and an additional erase circuit for additionally erasing data from the memory cell in the excess-written state.
摘要:
An EEPROM includes an array of memory cell transistors, which is divided into cell blocks each including NAND cell units of series-connected cell transistors. A sense amplifier is connected to bit lines and a comparator. A data-latch circuit is connected to the comparator, for latching a write-data supplied from a data input buffer. After desired cell transistors selected for programming in a selected block are once programmed, a write-verify operation is performed. The comparator compares the actual data read from one of the programmed cell transistors with the write-data, to verify its written state. The write-verify process checks the resulting threshold voltage for variations using first and second reference voltages defining the lower-limit and upper-limit of an allowable variation range. If the comparison results under employment of the first voltage shows that an irregularly written cell transistor remains with an insufficient threshold voltage which is so low as to fail to fall within the range, the write operation continues for the same cell transistor. If the comparison results under employment of the second voltage shows that an excess-written cell transistor remains, the block is rendered "protected" at least partially.
摘要:
An EEPROM includes an array of memory cell transistors, which is divided into cell blocks each including NAND cell units of series-connected cell transistors. A sense amplifier is connected to bit lines and a comparator. A data-latch circuit is connected to the comparator, for latching a write-data supplied from a data input buffer. After desired cell transistors selected for programming in a selected block are once programmed, a write-verify operation is performed. The comparator compares the actual data read from one of the programmed cell transistors with the write-data, to verify its written state. The write-verify process checks the resulting threshold voltage for variations using first and second reference voltages defining the lower-limit and upper-limit of an allowable variation range. If the comparison results under employment of the first voltage shows that an irregularly written cell transistor remains with an insufficient threshold voltage which is so low as to fail to fall within the range, the write operation continues for the same cell transistor. If the comparison results under employment of the second voltage shows that an excess-written cell transistor remains, the block is rendered "protected" at least partially.
摘要:
A NAND cell type EEPROM has parallel data transmission lines formed above a substrate, and a memory cell section including a plurality of NAND type cell units containing a NAND type cell unit that is associated with a certain bit line of the bit lines. This NAND type cell unit has a series-circuit of a preselected number of data storage transistors with control gates, and a selection transistor. A substrate voltage-stabilizing layer is insulatively provided above the substrate and positioned in the field area in adjacent to the certain bit line. The conductive layer is connected to the substrate by a contact portion so that the substrate voltage can be constantly set to a preselected voltage potential of a fixed value during the NAND type cell unit is being subjected to the write and erase modes.
摘要:
A non-volatile semiconductor memory device includes a semiconductor substrate, a memory cell including source and drain regions formed in a surface region of the semiconductor substrate, and a first gate insulating film, a charge storage layer, a second gate insulating film, and a control gate sequentially stacked on the semiconductor substrate, the memory cell being capable of electrically rewriting data by exchanging charges between the charge storage layer and the semiconductor substrate, and a means for applying a high potential to the semiconductor substrate and an intermediate potential to the control gate in a first data erase operation, and applying a high potential to the semiconductor substrate and a low potential to the control gate in second and subsequent data erase operations, thereby removing electrons from the charge storage layer.
摘要:
A non-volatile semiconductor memory device includes a semiconductor substrate, a memory cell including source and drain regions formed in a surface region of the semiconductor substrate, and a first gate insulating film, a charge storage layer, a second gate insulating film, and a control gate sequentially stacked on the semiconductor substrate, the memory cell being capable of electrically rewriting data by exchanging charges between the charge storage layer and the semiconductor substrate, and a means for applying a high potential to the semiconductor substrate and an intermediate potential to the control gate in a first data erase operation, and applying a high potential to the semiconductor substrate and a low potential to the control gate in second and subsequent data erase operations, thereby removing electrons from the charge storage layer.
摘要:
A non-volatile semiconductor memory device includes a semiconductor substrate, a memory cell including source and drain regions formed in a surface region of the semiconductor substrate, and a first gate insulating film, a charge storage layer, a second gate insulating film, and a control gate sequentially stacked on the semiconductor substrate, the memory cell being capable of electrically rewriting data by exchanging charges between the charge storage layer and the semiconductor substrate, and a means for applying a high potential to the semiconductor substrate and an intermediate potential to the control gate in a first data erase operation, and applying a high potential to the semiconductor substrate and a low potential to the control gate in second and subsequent data erase operations, thereby removing electrons from the charge storage layer.
摘要:
A non-volatile semiconductor memory device includes a semiconductor substrate, a memory cell including source and drain regions formed in a surface region of the semiconductor substrate, and a first gate insulating film, a charge storage layer, a second gate insulating film, and a control gate sequentially stacked on the semiconductor substrate, the memory cell being capable of electrically rewriting data by exchanging charges between the charge storage layer and the semiconductor substrate, and a means for applying a high potential to the semiconductor substrate and an intermediate potential to the control gate in a first data erase operation, and applying a high potential to the semiconductor substrate and a low potential to the control gate in second and subsequent data erase operations, thereby removing electrons from the charge storage layer.
摘要:
A non-volatile semiconductor memory device includes a semiconductor substrate, a memory cell including source and drain regions formed in a surface region of the semiconductor substrate, and a first gate insulating film, a charge storage layer, a second gate insulating film, and a control gate sequentially stacked on the semiconductor substrate, the memory cell being capable of electrically rewriting data by exchanging charges between the charge storage layer and the semiconductor substrate, and a means for applying a high potential to the semiconductor substrate and an intermediate potential to the control gate in a first data erase operation, and applying a high potential to the semiconductor substrate and a low potential to the control gate in second and subsequent data erase operations, thereby removing electrons from the charge storage layer.