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Memory reading method and memory device

A memory and memory array technology, applied in static memory, read-only memory, digital memory information, etc., can solve the problem of inaccurate read data

Active Publication Date: 2020-05-26
MACRONIX INT CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The threshold voltage of a memory cell can change over time, so that using a fixed read level can result in inaccurate reading of data from the memory cell

Method used

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  • Memory reading method and memory device

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Experimental program
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Embodiment Construction

[0039] Memory cells in a memory array, such as a NAND flash memory chip, can be read by applying a voltage of a specific voltage level to the gate of the memory cell, for example to obtain the value of one or more bits stored in the memory cell, which The specific voltage level is called the read level of the memory cell. The read level may be a fixed value within a limited range of allowable voltage, which is called a read window (read window).

[0040] Figure 1A and Figure 1B An example of a read operation performed on a memory cell using a fixed read level is shown. Such as Figure 1AAs shown, a read window of a memory array, such as a read window of a page or a chunk of memory is marked 110, has a lower limit voltage level X1 and an upper limit voltage level X2. Threshold voltage distributions 120 and 130 are used to program memory cells, eg, write data to or erase data from memory cells.

[0041] The memory cells in the memory array are ECC-correctable. That is, the...

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Abstract

The invention provides a memory reading method. The memory read method comprises the steps of: performing a first read operation using a first voltage level to read data from the memory array; determining an instantaneous bit corresponding to the number of bits of the data read from the memory array counting; obtaining a recorded bit count corresponding to the number of bits of written data written to the memory array at a time; obtaining a difference between the instantaneous bit count and the recorded bit count; Once it is determined that the difference is less than or equal to a first critical value, output the data read from the memory array using the first read operation; once it is determined that the difference is greater than the first critical value, perform a second read operation to read from the memory The array reads data, and the second read operation uses a second voltage level different from the first voltage level.

Description

technical field [0001] The present invention is concerned with the reading of memory cells. Background technique [0002] Data stored in memory cells of a memory array can be read by applying a voltage, referred to as a read voltage level or read level, to the memory cells. In some memory arrays, the read level may be a fixed voltage level. The threshold voltage of a memory cell can change over time, so that using a fixed read level can result in inaccuracies in reading data from the memory cell. Contents of the invention [0003] This disclosure describes devices, systems, and techniques that improve the accuracy of read operations performed on memory cells of a memory array. In one embodiment, when writing data to a memory cell in a memory array, such as a flash memory chip, the number of "high threshold voltage" or "low threshold voltage" bits in the data is calculated and stored as a record Count number (recorded count number, rCN). In some embodiments, the high th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G11C16/26
CPCG11C16/26G06F11/1048G11C11/5642G06F11/108
Inventor 洪俊雄陈汉松林明昭
Owner MACRONIX INT CO LTD