NAND Boosting Using Dynamic Ramping of Word Line Voltages
First Claim
1. A method for operating a non-volatile storage system, comprising:
- acquiring data to be programmed into a set of memory cells within a memory array;
determining a programming waveform to be applied to a selected word line connected to the set of memory cells, the programming waveform includes a voltage ramp to a programming voltage;
determining a first voltage waveform to be applied to a first grouping of unselected word lines within the memory array, the first voltage waveform includes a first initial ramp to a first initial voltage and a first final ramp to a pass voltage, the pass voltage is greater than the first initial voltage, the pass voltage is less than the programming voltage; and
performing a programming operation to program the data into the set of memory cells, the programming operation includes applying the programming voltage waveform to the selected word line and applying the first voltage waveform to the first grouping of unselected word lines such that the first final ramp to the pass voltage occurs after the selected word line has been set to the programming voltage, the pass voltage comprises a maximum voltage applied to the first grouping of unselected word lines during the programming operation.
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Abstract
Methods for improving channel boosting and reducing program disturb during programming of memory cells within a memory array are described. The memory array may comprise a NAND flash memory structure, such as a vertical NAND structure or a bit cost scalable (BiCS) NAND structure. In some cases, by applying continuous voltage ramping to unselected word lines during or throughout a programming operation, the boosting of channels associated with program inhibited memory cells may be improved. In one example, the slope and timing of a Vpass waveform applied to a group of unselected word lines (e.g., the neighboring word lines of the selected word line) during the programming operation may be set based on the location of the selected word line within the memory array and the locations of the group of unselected word lines within the memory array.
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Citations
20 Claims
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1. A method for operating a non-volatile storage system, comprising:
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acquiring data to be programmed into a set of memory cells within a memory array; determining a programming waveform to be applied to a selected word line connected to the set of memory cells, the programming waveform includes a voltage ramp to a programming voltage; determining a first voltage waveform to be applied to a first grouping of unselected word lines within the memory array, the first voltage waveform includes a first initial ramp to a first initial voltage and a first final ramp to a pass voltage, the pass voltage is greater than the first initial voltage, the pass voltage is less than the programming voltage; and performing a programming operation to program the data into the set of memory cells, the programming operation includes applying the programming voltage waveform to the selected word line and applying the first voltage waveform to the first grouping of unselected word lines such that the first final ramp to the pass voltage occurs after the selected word line has been set to the programming voltage, the pass voltage comprises a maximum voltage applied to the first grouping of unselected word lines during the programming operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A non-volatile storage system, comprising:
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a memory array, the memory array includes a set of memory cells; and one or more managing circuits in communication with the memory array, the one or more managing circuits configured to acquire data to be programmed into the set of memory cells and configured to determine a programming waveform to be applied to a selected word line connected to the set of memory cells, the programming waveform includes a voltage ramp to a programming voltage, the one or more managing circuits configured to determine a first voltage waveform to be applied to a first grouping of unselected word lines within the memory array, the first voltage waveform includes a first initial ramp to a first initial voltage and a first final ramp to a pass voltage, the pass voltage is greater than the first initial voltage, the pass voltage is less than the programming voltage, the one or more managing circuits configured to initiate a programming operation to program the data into the set of memory cells, the one or more managing circuits configured to cause the programming voltage waveform to be applied to the selected word line during the programming operation and configured to cause the first voltage waveform to be applied to the first grouping of unselected word lines during the programming operation such that the first final ramp to the pass voltage occurs after the selected word line has been set to the programming voltage, the pass voltage comprises a maximum voltage applied to the first grouping of unselected word lines during the programming operation. - View Dependent Claims (16, 17, 18, 19)
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20. A method for operating a non-volatile storage system, comprising:
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acquiring data to be programmed into a set of floating gate transistors within a memory array; determining a programming waveform to be applied to a selected word line connected to the set of floating gate transistors, the programming waveform includes a voltage ramp to a programming voltage; determining a first voltage waveform to be applied to a first grouping of unselected word lines within the memory array, the first voltage waveform includes a first ramp to a pass voltage, the pass voltage is less than the programming voltage; and performing a programming operation to program the data into the set of floating gate transistors, the programming operation includes applying the programming voltage waveform to the selected word line and applying the first voltage waveform to the first grouping of unselected word lines such that a continuous voltage ramping of the first grouping of unselected word lines occurs throughout the programming operation, the pass voltage comprises a maximum voltage applied to the first grouping of unselected word lines during the programming operation.
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Specification