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CN-114360612-B - Read voltage level correction method, memory storage device and control circuit unit

CN114360612BCN 114360612 BCN114360612 BCN 114360612BCN-114360612-B

Abstract

The invention provides a read voltage level correction method, a memory storage device and a memory control circuit unit. The method includes performing a first data read operation on a first physical cell of the plurality of physical cells using the first read voltage level as a starting read voltage level to obtain a second read voltage level used to successfully read the first physical cell, recording association information between the first read voltage level and the second read voltage level in a transient lookup table, and performing a second data read operation according to the association information recorded in the read voltage level tracking table and the transient lookup table.

Inventors

  • ZENG SHIJIA
  • CAO JUNWEI
  • LIN XIAOYI
  • LIN WEI

Assignees

  • 群联电子股份有限公司

Dates

Publication Date
20260505
Application Date
20220110

Claims (18)

  1. 1. A read voltage level correction method for a rewritable non-volatile memory module, the rewritable non-volatile memory module comprising a plurality of physical cells, the method comprising: Performing a first data read operation on a first physical cell of the plurality of physical cells using the first read voltage level as a starting read voltage level to obtain a second read voltage level used to successfully read the first physical cell; Recording association information between the first read voltage level and the second read voltage level in a transient lookup table, wherein the step of recording the association information between the first read voltage level and the second read voltage level in the transient lookup table comprises: Counting the number of times that the first reading voltage level and the second reading voltage level have correlation to generate a count value; Recording the count value in the transient look-up table, and Performing a second data read operation based on the association information recorded in the transient look-up table and the read voltage level tracking table, Wherein the read voltage level tracking table records a plurality of optimal read voltage levels for the plurality of physical cells, Wherein performing the second data read operation according to the read voltage level tracking table and the associated information recorded in the transient lookup table comprises: retrieving a second optimal read voltage level for a second physical cell of the plurality of physical cells from the read voltage level tracking table when the second data read operation indicates reading of data for the second physical cell, and And searching the transient lookup table according to the second optimal reading voltage level or an index value corresponding to the second optimal reading voltage level, so as to take the second reading voltage level corresponding to the maximum count value in a plurality of count values as a starting reading voltage level for executing the second data reading operation.
  2. 2. The method of read voltage level correction of claim 1, wherein the step of performing the first data read operation on the first one of the plurality of physical cells using the first read voltage level as the starting read voltage level further comprises: A first optimal read voltage level corresponding to the first physical unit is obtained from the read voltage level tracking table as the first read voltage level.
  3. 3. The method of read voltage level correction of claim 1, wherein the step of performing the first data read operation on the first one of the plurality of physical cells using the first read voltage level as the starting read voltage level further comprises: the first reading voltage level is determined according to the association information recorded in the reading voltage level tracking table and the transient lookup table.
  4. 4. The read voltage level correction method of claim 1, wherein the method comprises: A decoding operation is performed when the first data read operation is performed on the first entity unit of the plurality of entity units using the first read voltage level as the starting read voltage level or when the second data read operation is performed according to the association information recorded in the read voltage level tracking table and the transient lookup table.
  5. 5. The method of read voltage level correction according to claim 1, wherein the step of performing the second data read operation according to the read voltage level tracking table and the associated information recorded in the transient lookup table further comprises: And searching the transient lookup table according to the second optimal reading voltage level or the index value corresponding to the second optimal reading voltage level, so as to sequentially obtain the second reading voltage level corresponding to the count value according to the sequence from the next highest count value to the next lowest count value as the initial reading voltage level for executing the second data reading operation.
  6. 6. The read voltage level correction method of claim 1, wherein the method further comprises: updating the read voltage level tracking table based on the association information recorded in the transient lookup table, and The transient look-up table is cleared after updating the read voltage level tracking table.
  7. 7. A memory storage device, comprising: the connection interface unit is used for being coupled to the host system; a rewritable nonvolatile memory module includes a plurality of physical units, and A memory control circuit unit coupled to the connection interface unit and the rewritable nonvolatile memory module, Wherein the memory control circuit unit is configured to perform a first data read operation on a first physical unit of the plurality of physical units using a first read voltage level as a start read voltage level to obtain a second read voltage level used to successfully read the first physical unit, The memory control circuit unit is further configured to record association information between the first read voltage level and the second read voltage level in a transient lookup table, wherein the association information between the first read voltage level and the second read voltage level is recorded in operation of the transient lookup table, The memory control circuit unit is also used for counting the times of correlation between the first reading voltage level and the second reading voltage level to generate a count value, and The memory control circuit unit is also used for recording the count value in the transient lookup table and The memory control circuit unit is also configured to perform a second data read operation based on the read voltage level tracking table and the associated information recorded in the transient lookup table, Wherein the read voltage level tracking table records a plurality of optimal read voltage levels for the plurality of physical cells, Wherein the memory control circuit unit is further operative to perform the second data read operation in accordance with the read voltage level tracking table and the associated information recorded in the transient lookup table, comprising: The memory control circuit unit is further configured to obtain a second optimal read voltage level of a second physical unit of the plurality of physical units from the read voltage level tracking table when the second data read operation indicates to read the data of the second physical unit, and The memory control circuit unit is further configured to search the transient lookup table according to the second optimal read voltage level or an index value corresponding to the second optimal read voltage level, so as to use the second read voltage level corresponding to a maximum count value of the plurality of count values as a start read voltage level for executing the second data read operation.
  8. 8. The memory storage device of claim 7, wherein the memory control circuit unit is further configured to obtain a first optimal read voltage level corresponding to the first physical cell from the read voltage level tracking table as the first read voltage level.
  9. 9. The memory storage device of claim 7, wherein the memory control circuit unit is further to determine the first read voltage level based on the read voltage level tracking table and the association information recorded in the transient lookup table.
  10. 10. The memory storage device of claim 7, wherein the memory control circuit unit is further to perform a decoding operation when performing the first data read operation on the first one of the plurality of physical units using the first read voltage level as the starting read voltage level or when performing the second data read operation according to the association information recorded in the read voltage level tracking table and the transient lookup table.
  11. 11. The memory storage device of claim 7, wherein in performing the second data read operation based on the read voltage level tracking table and the associated information recorded in the transient lookup table, The memory control circuit unit is further configured to search the transient lookup table according to the second optimal read voltage level or the index value corresponding to the second optimal read voltage level, so as to sequentially obtain the second read voltage level corresponding to the count value as the initial read voltage level for executing the second data read operation according to the order of the count values from the next highest to the next lowest.
  12. 12. The memory storage device of claim 7, wherein the memory control circuit unit is further to update the read voltage level tracking table according to the association information recorded in the transient lookup table, and The memory control circuit unit is also configured to clear the transient lookup table after updating the read voltage level tracking table.
  13. 13. A memory control circuit unit for controlling a rewritable non-volatile memory module comprising a plurality of physical units, wherein the memory control circuit unit comprises: a host interface for coupling to a host system; a memory interface for coupling to the rewritable non-volatile memory module; Error checking and correcting circuit, and A memory management circuit coupled to the host interface, the memory interface, and the error checking and correcting circuit, Wherein the memory management circuit is configured to perform a first data read operation on a first physical cell of the plurality of physical cells using a first read voltage level as a starting read voltage level to obtain a second read voltage level used to successfully read the first physical cell, The memory management circuit is further configured to record association information between the first read voltage level and the second read voltage level in a transient lookup table, wherein the association information between the first read voltage level and the second read voltage level is recorded in operation of the transient lookup table, The memory management circuit is further configured to count a number of times that there is a correlation between the first read voltage level and the second read voltage level to generate a count value, and The memory management circuit is also configured to record the count value in the transient lookup table and The memory management circuit is also configured to perform a second data read operation based on the read voltage level tracking table and the associated information recorded in the transient lookup table, Wherein the read voltage level tracking table records a plurality of optimal read voltage levels for the plurality of physical cells, Wherein the memory management circuitry is further to perform the second data read operation in accordance with the read voltage level tracking table and the associated information recorded in the transient lookup table, comprising: The memory management circuit is further configured to obtain a second optimal read voltage level of a second physical unit of the plurality of physical units from the read voltage level tracking table when the second data read operation indicates to read data of the second physical unit, and The memory management circuit is further configured to search the transient lookup table according to the second optimal read voltage level or an index value corresponding to the second optimal read voltage level, so as to use the second read voltage level corresponding to a maximum count value of the plurality of count values as a start read voltage level for executing the second data read operation.
  14. 14. The memory control circuit unit of claim 13, wherein the memory management circuit is further configured to obtain a first optimal read voltage level corresponding to the first physical unit from the read voltage level tracking table as the first read voltage level.
  15. 15. The memory control circuit unit of claim 13, wherein the memory management circuit is further configured to determine the first read voltage level based on the read voltage level tracking table and the association information recorded in the transient lookup table.
  16. 16. The memory control circuit unit of claim 13, wherein the memory management circuit is further to perform a decoding operation when the first read operation is performed on the first physical unit of the plurality of physical units using the first read voltage level as the starting read voltage level or when the second data read operation is performed according to the association information recorded in the read voltage level tracking table and the transient lookup table.
  17. 17. The memory control circuit unit of claim 13, wherein in performing the second data read operation based on the read voltage level tracking table and the associated information recorded in the transient lookup table, The memory management circuit is further configured to search the transient lookup table according to the second optimal read voltage level or the index value corresponding to the second optimal read voltage level, so as to sequentially obtain the second read voltage level corresponding to the count value according to the order of the count values from the next highest to the next lowest, as the initial read voltage level for executing the second data read operation.
  18. 18. The memory control circuit unit of claim 13, wherein the memory management circuit is further to update the read voltage level tracking table according to the association information recorded in the transient lookup table, and The memory management circuit is also to clear the transient lookup table after updating the read voltage level tracking table.

Description

Read voltage level correction method, memory storage device and control circuit unit Technical Field The present invention relates to a read voltage level tracking method, and more particularly, to a read voltage level correction method for a rewritable nonvolatile memory module, a memory storage device and a memory control circuit unit. Background Portable electronic devices such as notebook computers and mobile phones have grown very rapidly over the years, and consumer demand for storage media has also increased rapidly. Since a rewritable non-volatile memory (e.g., flash memory) has characteristics of non-volatility of data, power saving, small size, no mechanical structure, and fast read/write speed, it is very suitable for being built in the various portable electronic devices as exemplified above. Solid state disk is a memory storage device using flash memory module as storage medium. Therefore, the flash memory industry has recently become a very popular ring in the electronics industry. When reading data, the memory storage device reads the data according to a preset reading voltage level. However, as the operation and environmental conditions of the memory modules in the memory storage device are different, the threshold voltages of the memory modules are also shifted. In this case, there may be too many erroneous bits for reading data using a preset read voltage level. Generally, the memory storage device finds the optimal read voltage level by performing an optimal read voltage level tracking operation. In the optimum read voltage level tracking operation, the memory storage device continuously monitors and records the optimum read voltage level of the memory module. However, the current operating and environmental conditions (e.g., temperature) under which the memory storage device actually reads data may be different from the conditions under which the optimal read voltage level was last monitored. Or the memory storage device may not continuously monitor the optimal read voltage level due to the host system powering down or entering a low power consumption mode, resulting in too long a time interval between the actual data read and the previous monitoring time. As operating and environmental conditions change and time passes, the optimal read voltage level of the memory module may shift further, such that the optimal read voltage level found previously is out of alignment. The direct use of the previously monitored results may instead lead to a deterioration in the performance of the read operation. Disclosure of Invention The invention provides a read voltage level correction method, a memory storage device and a memory control circuit unit, which can reduce the time for searching for the voltage level which can be successfully read by a physical unit, thereby increasing the efficiency of the whole data reading operation. The invention provides a read voltage level correction method for a rewritable nonvolatile memory module, which comprises a plurality of entity units. The method includes performing a first data read operation on a first physical cell of the plurality of physical cells using a first read voltage level as a starting read voltage level to obtain a second read voltage level used to successfully read the first physical cell, recording association information between the first read voltage level and the second read voltage level in a transient lookup table, and performing a second data read operation according to the association information recorded in a read voltage level tracking table and the transient lookup table. The read voltage level tracking table records a plurality of optimal read voltage levels of the plurality of physical units. In an embodiment of the present invention, the step of performing the first data reading operation on the first physical unit of the plurality of physical units using the first reading voltage level as the initial reading voltage level further includes obtaining a first optimal reading voltage level corresponding to the first physical unit from the reading voltage level tracking table as the first reading voltage level. In an embodiment of the present invention, the step of performing the first data reading operation on the first physical unit of the plurality of physical units using the first reading voltage level as the initial reading voltage level further includes determining the first reading voltage level according to the reading voltage level tracking table and the association information recorded in the transient lookup table. In an embodiment of the present invention, the method includes performing a decoding operation when the first data read operation is performed on the first entity unit of the plurality of entity units using the first read voltage level as the start read voltage level or when the second data read operation is performed according to the association information recorded in the read voltage level tracking table and