摘要:
The process for programming a set of memory cells is improved by adapting the programming process based on behavior of the memory cells. For example, a set of program pulses is applied to the word line for a set of flash memory cells. A determination is made as to which memory cells are easier to program and which memory cells are harder to program. Bit line voltages (or other parameters) can be adjusted based on the determination of which memory cells are easier to program and which memory cells are harder to program. The programming process will then continue with the adjusted bit line voltages (or other parameters).
摘要:
The process for programming a set of memory cells is improved by adapting the programming process based on behavior of the memory cells. For example, a set of program pulses is applied to the word line for a set of flash memory cells. A determination is made as to which memory cells are easier to program and which memory cells are harder to program. Bit line voltages (or other parameters) can be adjusted based on the determination of which memory cells are easier to program and which memory cells are harder to program. The programming process will then continue with the adjusted bit line voltages (or other parameters).
摘要:
The present invention presents a number of methods for identifying cells with poor subthreshold slope and reduced transconductance. A first set of techniques focuses on the poor subthreshold behavior of degraded storage elements by cycling cells and then programming them to a state above the ground state and the reading them with a control gate voltage below the threshold voltage of this state to see if they still conduct. A second set of embodiments focuses on weak transconductance behavior by reading programmed cells with a control gate voltage well above the threshold voltage. A third set of embodiments alters the voltage levels at the source-drain regions of the storage elements. The current-voltage curve of a good storage element is relatively stable under this shift in bias conditions, while degraded elements exhibit a larger shift. The amount of shift can be used to differentiate the good elements from the bad.
摘要:
The present invention presents a number of methods for identifying cells with poor subthreshold slope and reduced transconductance. A first set of techniques focuses on the poor subthreshold behavior of degraded storage elements by cycling cells and then programming them to a state above the ground state and the reading them with a control gate voltage below the threshold voltage of this state to see if they still conduct. A second set of embodiments focuses on weak transconductance behavior by reading programmed cells with a control gate voltage well above the threshold voltage. A third set of embodiments alters the voltage levels at the source-drain regions of the storage elements. The current-voltage curve of a good storage element is relatively stable under this shift in bias conditions, while degraded elements exhibit a larger shift. The amount of shift can be used to differentiate the good elements from the bad.
摘要:
In a non-volatile semiconductor memory system (or other type of memory system), a memory cell is programmed by changing the threshold voltage of that memory cell. Because of variations in the programming speeds of different memory cells in the system, the possibility exists that some memory cells will be over programmed. That is, in one example, the threshold voltage will be moved past the intended value or range of values. The present invention includes determining whether the memory cells are over programmed.
摘要:
In a non-volatile semiconductor memory system (or other type of memory system), a memory cell is programmed by changing the threshold voltage of that memory cell. Because of variations in the programming speeds of different memory cells in the system, the possibility exists that some memory cells will be over programmed. That is, in one example, the threshold voltage will be moved past the intended value or range of values. The present invention includes determining whether the memory cells are over programmed.
摘要:
In a non-volatile semiconductor memory system (or other type of memory system), a memory cell is programmed by changing the threshold voltage of that memory cell. Because of variations in the programming speeds of different memory cells in the system, the possibility exists that some memory cells will be over programmed. That is, in one example, the threshold voltage will be moved past the intended value or range of values. The present invention includes determining whether the memory cells are over programmed.
摘要:
A non-volatile semiconductor memory system (or other type of memory system) is programmed in a manner that avoids program disturb. In one embodiment that includes a flash memory system using a NAND architecture, program disturb is avoided by increasing the channel potential of the source side of the NAND string during the programming process. One exemplar implementation includes applying a voltage (e.g. Vdd) to the source contact and turning on the source side select transistor for the NAND sting corresponding to the cell being inhibited. Another implementation includes applying a pre-charging voltage to the unselected word lines of the NAND string corresponding to the cell being inhibited prior to applying the program voltage.
摘要:
The process for programming a set of memory cells is improved by adapting the programming process based on behavior of the memory cells. For example, a set of program pulses is applied to the word line for a set of flash memory cells. A determination is made as to which memory cells are easier to program and which memory cells are harder to program. Bit line voltages (or other parameters) can be adjusted based on the determination of which memory cells are easier to program and which memory cells are harder to program. The programming process will then continue with the adjusted bit line voltages (or other parameters).
摘要:
A number of methods for identifying cells with poor subthreshold slope and reduced transconductance. A first set of techniques focuses on the poor subthreshold behavior of degraded storage elements by cycling cells and then programming them to a state above the ground state and the reading them with a control gate voltage below the threshold voltage of this state to see if they still conduct. A second set of embodiments focuses on weak transconductance behavior by reading programmed cells with a control gate voltage well above the threshold voltage. A third set of embodiments alters the voltage levels at the source-drain regions of the storage elements. The current-voltage curve of a good storage element is relatively stable under this shift in bias conditions, while degraded elements exhibit a larger shift. The amount of shift can be used to differentiate the good elements from the bad.