Programming of multi-level memory cells on a continuous word line
First Claim
1. A write operation for a non-volatile memory, comprising:
- (a) applying a first programming voltage to a word line that is connected to multiple selected memory cells that are being simultaneously programmed to respective target threshold voltages that represent respective values being written;
(b) applying a second programming voltage to a set of column lines that are connected to the selected memory cells, wherein application of the first programming voltage and the second programming voltage change threshold voltages of the selected memory cells; and
(c) determining which of the selected memory cells have reached the respective target threshold voltages that represent the respective values;
(d) removing from the set of column lines any column lines connected to the selected memory cells determined to have reached the respective target threshold voltages;
(e) changing the first programming voltage; and
(f) repeating steps (a) to (e) until the set of column lines is empty, wherein for a series of repetitions of step (e) an amount of change in the first programming voltage differs from amounts of change in preceding executions of step (e).
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Abstract
Write operations that simultaneously program multiple memory cells on the same word line in an MBPC or MLC non-volatile memory employ word line voltage variation, programming pulse width variation, and column line voltage variation to achieve uniform programming accuracy across a range of target threshold voltages. One type of write operation reaches target threshold voltages during respective time intervals and in each time interval uses programming parameters that optimize threshold voltage resolution for the target threshold voltage corresponding to that interval. During or at the end of write operations or the ends of each interval, remedial programming sequences can adjust the threshold voltages of memory cells that program slowly.
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Citations
30 Claims
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1. A write operation for a non-volatile memory, comprising:
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(a) applying a first programming voltage to a word line that is connected to multiple selected memory cells that are being simultaneously programmed to respective target threshold voltages that represent respective values being written; (b) applying a second programming voltage to a set of column lines that are connected to the selected memory cells, wherein application of the first programming voltage and the second programming voltage change threshold voltages of the selected memory cells; and (c) determining which of the selected memory cells have reached the respective target threshold voltages that represent the respective values; (d) removing from the set of column lines any column lines connected to the selected memory cells determined to have reached the respective target threshold voltages; (e) changing the first programming voltage; and (f) repeating steps (a) to (e) until the set of column lines is empty, wherein for a series of repetitions of step (e) an amount of change in the first programming voltage differs from amounts of change in preceding executions of step (e). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A write operation for a non-volatile memory, comprising:
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(a) applying a first programming voltage to a word line that is connected to multiple selected memory cells that are being simultaneously programmed to respective target threshold voltages that represent respective values being written; (b) applying a second programming voltage to a set of column lines that are connected to the selected memory cells, wherein application of the first programming voltage and the second programming voltage change threshold voltages of the selected memory cells; and (c) determining which of the selected memory cells have reached the respective target threshold voltages that represent the respective values; (d) removing from the set of column lines any column lines connected to the selected memory cells determined to have reached the respective target threshold voltages; and (e) repeating steps (a) to (d) until the set of column lines is empty, wherein for a series of repetitions of step (a) a duration of application of the first programming voltage differs from durations of preceding executions of step (a). - View Dependent Claims (12, 13, 14, 15, 16)
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17. A write operation for a non-volatile memory, comprising applying a write signal to a word line that is connected to multiple selected memory cells that are being simultaneously programmed, wherein the selected memory cells are being programmed to respective target threshold voltages that represent respective multi-bit data values being written, and the write signal includes:
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a plurality of programming cycles during which programming voltages applied to the selected memory cells change threshold voltages of the selected memory cells; and a plurality of verify cycles during which sensing operations determine whether the selected memory cells have reached the respective target threshold voltages, wherein the programming cycles have shorter duration at an end of a first interval than at a start of the first interval;
increase in duration immediately after the first interval, and for a second interval that follows the first interval have shorter duration at an end of the second interval than at a start of the second interval. - View Dependent Claims (18, 19, 20)
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21. A write operation for a non-volatile memory, comprising:
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(a) starting an interval for programming that includes; (b) applying first programming pulses to a word line that is connected to multiple selected memory cells that are being simultaneously programmed to respective target threshold voltages that represent respective values being written; (b) applying second programming pulses to a set of column lines that are connected to the selected memory cells, wherein application of the first programming pulses and the second programming pulses change threshold voltages of the selected memory cells; and (c) determining which of the selected memory cells have reached a target threshold voltage that corresponds to the interval; (d) removing from the set of column lines any column lines connected to the selected memory cells that was determined to have reached the target threshold voltage corresponding to the interval; (e) repeating steps (b) to (d) until the set of column lines is empty; and (f) repeating steps (a) to (e) until the selected memory cells have reached the respective target threshold voltages. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification