Testing and processing method for Open Block

A technology of testing method and processing method, which is applied in the field of nandflash testing, can solve problems such as the inability to guarantee the correctness and inconsistency of openblock valid data reading, and achieve the effect of reducing the risk of data errors

Pending Publication Date: 2021-05-28
SHANDONG SINOCHIP SEMICON
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Generally speaking, the factors that affect the storage of data in NAND Flash mainly include PE counts, data retention, read disturbance, and temperature changes, but their influence on close block and open block is not the same. Not the same, so if you use the same processing strategy as the close block for the open block, the correctness of reading valid data in the open block cannot be guaranteed, especially for the edge page (WL), it is necessary to protect the edge page or word line data stability

Method used

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  • Testing and processing method for Open Block
  • Testing and processing method for Open Block
  • Testing and processing method for Open Block

Examples

Experimental program
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Embodiment 1

[0024] This embodiment discloses a test method for an Open Block. This method includes the first part, one part is to test to obtain the edge WL, and the other part is to test to obtain the optimal voltage axis of the edge WL.

[0025] This embodiment takes one-pass 3D TLC as an example to describe a test method for an open block, and provides a processing method for an open block by comparing it with a close block. Assuming that each block of 3D TLC has N WLs, the close block means that all N WLs are filled with data, and the open block means that only k WLs are written, k ∈ (0, N).

[0026] The process of testing the edge WL is:

[0027] S01), select a block as the test block, for this block, starting from writing WL0, every time the data of a WL is written, read all WLs that have been written, and record the number of error bits of all read WL data Down, until the current block is filled, so as to get all the FBC conditions in the entire block writing process;

[0028] S0...

Embodiment 2

[0061] This embodiment discloses a processing method for Open Block. Based on the test results of Embodiment 1, this method uses the optimal voltage axis to read the edge WL data for the edge WL of the open block; for an OpenBlock with m edge WL, In order to ensure that the k WL data stability of the open block is consistent with that of the close block, it is necessary to write at least s WL backwards. Among them, s redundant WLs write random data.

[0062] The test method described in the present invention can quickly obtain the data characteristics stored in the open block, and the corresponding parameter values ​​can be quickly obtained through the obtained specific data. At the same time, the erasing times (PEcounts) and data storage time (data Retention), the number of reads (read disturbance) and temperature changes affect the stability of NAND Flash data, and finally determine the corresponding processing method according to the test results. In addition, the open blo...

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Abstract

The invention discloses a test method for an Open Block, and the method comprises the steps: for a block, starting from the writing of WL0, reading all WLs with written data every time the data of one WL is written, and recording the data error bits of all read WLs until the current block is fully written; starting from the WL0, analyzing the change condition of the FBC of the WL0 in the write-in process from the WL0 to the WLN, and obtaining the change condition of all N WLs in the write-in process, wherein according to the process, it is obtained that it needs to be guaranteed that the stability of k WL data of the open block is consistent with that of the close block, and at least s WLs need to be written backwards from the WL k. According to the method, the edge page or the edge word line of the open block is obtained through testing, the open block is processed in a targeted mode according to the result obtained through the testing method, and data reading errors caused by the open block problem are avoided.

Description

technical field [0001] The invention relates to a test and processing method for Open Block, which belongs to the technical field of nand flash test. Background technique [0002] NAND Flash is a storage medium widely used at present. NAND Flash uses a block as the erasing unit and a page as the reading and writing unit. During use, it is very easy for some pages of some blocks to not write data. , this kind of block that is not filled with data is called an open block. The data stored in the Open block is less stable, especially when reading the edge pages, there is a high probability of a large number of data bit errors, which may appear as data error correction failures when applied to the system. [0003] Specifically, an Open block refers to a block that is not completely filled. NAND Flash uses a block as the erasing unit, and a page or word line (WL) as the reading and writing unit. During use, if all pages or WLs of a block are not fully written, we will It is cal...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11C29/56
CPCG11C29/56
Inventor 刘凯王璞
Owner SHANDONG SINOCHIP SEMICON
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