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A method for repairing defect of multi-sub-block nand flash memory
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A repair method and defect technology, applied in the field of NAND flash memory devices, can solve problems such as long use time and inability to guarantee resources, and achieve the effects of reducing times, increasing data storage space, and reducing capacity
Active Publication Date: 2021-10-22
XI AN UNIIC SEMICON CO LTD
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Problems solved by technology
In some extreme cases, the number of defects is large, and this method takes a long time, and this method cannot guarantee the least resources used, especially the defect problem of multi-sub-block NAND flash memory, which has not been well solved.
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Embodiment 1
[0104] Figure 4 The conceptual layout of adding virtual redundant columns to the multi-sub-block (muti-area) NAND flash memory device embodiment is given, including two sub-blocks, and each sub-block contains 1120 columns (columns), including 1056 data columns and 64 Redundant columns. It also contains 2048 blocks and 128 virtual redundant rows.
[0105] The multi-sub-block NAND flash memory device includes 2048 blocks of 0, 1, 2, ..., 2047, each block includes 64 pages, and each page includes 2240 columns (including 2112 data columns and 128 redundant columns), these columns are physically The above is divided into multiple independent repair blocks (2, 4, 8...), and the example here is two sub-blocks.
[0106] Sub-block 1 contains 1056 data columns and 64 redundant columns, sub-block 2 contains 1056 data columns and 64 redundant columns, and column defects in sub-block 1 can only use 64 redundant columns in sub-block 1 The remaining columns are replaced, and the column d...
Embodiment 2
[0159] Step S170 starts:
[0160] Such as Image 6 , when proceeding to step S170, an available repair solution has been obtained, but the number of defective blocks is not the minimum, which will cause some blocks to be marked as bad blocks and be wasted. This method needs to carry out the results obtained in embodiment 1 optimization.
[0161] Step S200 judges redundant columns:
[0162] Specifically: step S200 will determine whether the redundant columns of each sub-block are used up, that is, determine whether the number of remaining redundant columns in each sub-block is 0. In this step, if the redundant columns of all sub-blocks have been used up, it means that the final repair result has been obtained and there is no need to optimize it, and the process directly proceeds to step S250 to end the process;
[0163] If there is at least one sub-block with remaining redundant columns, get the number of remaining redundant columns in each sub-block, the number of remaining...
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Abstract
The invention discloses a method for repairing defects in a multi-sub-block NAND flash memory, comprising: testing a multi-sub-block NAND flash memory device to find all blocks and columns containing defective storage cells, counting data rows and data columns where the defects are located The number of defects; sort the defective blocks and defect columns according to the number of defects; use redundancy to replace the data row and data column where the defect is located according to the sequence sorted list: use the redundant column to repair the defect column and write it as repair data into the flash memory to make the replacement take effect; first use the virtual redundant row to replace the defective block, the same row includes the same row address of multiple sub-blocks, and each sub-block uses the redundant column of the sub-block to replace the column defect of the sub-block; then It is necessary to write the address of the block corresponding to the defective block into the flash memory, and mark the defective block as a bad block. The method makes the repair algorithm of the NAND flash memory more concise, thereby making the whole process more efficient and improving the output of the test equipment.
Description
technical field [0001] The invention relates to the field of NAND flash memory devices, in particular to a method for repairing defects of multi-subblock NAND flash memory. Background technique [0002] There are three main types of defects in NAND flash memory: [0003] Row defects, column defects and scatter defects. [0004] For row defects, the block corresponding to the row is usually marked as a bad block; [0005] Replace column defects with redundant columns; [0006] Scattering point defects are the main problem solved by the present invention, because only using redundant columns to replace the columns where the scatter points are located often cannot achieve better test results, resulting in chips being screened and thus affecting yield. [0007] In the prior art, a method and device for repairing defects in NAND flash memory devices, publication number: 105097045A, publication date: 2015-11-25, can better solve this problem. like figure 1 As shown, first cou...
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