Method and apparatus for acquiring optimal threshold voltage, and nonvolatile storage device

Abstract

The present application discloses a method and apparatus for acquiring an optimal threshold voltage, a nonvolatile storage device, and a storage medium. The method comprises: acquiring a target scanning mode and a target scanning step size; on the basis of the target scanning mode and the target scanning step size, respectively performing a read operation on a target page in a NAND flash memory by means of at least one scanning voltage, and acquiring a syndrome value corresponding to each scanning voltage; and on the basis of the syndrome value corresponding to each scanning voltage, determining an optimal threshold voltage corresponding to the target page. Thus, the read operation is performed on the target page in the NAND flash memory by means of the at least one scanning voltage determined on the basis of the target scanning mode and the target scanning step size, and then the optimal threshold voltage corresponding to the target page is selected on the basis of the syndrome value, so that the voltage scanning range and the number of scans can be effectively reduced, thereby improving the accuracy and efficiency of acquiring the optimal threshold voltage.

Description

Method and device for obtaining optimal threshold voltage and non-volatile storage device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to a Chinese patent application filed with the Patent Office of China on August 25, 2023, with application number 202311077672.8 and entitled “Method, Apparatus and Non-Volatile Storage Device for Obtaining Optimal Threshold Voltage,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of storage devices, and in particular to a method and apparatus for obtaining an optimal threshold voltage, and a non-volatile storage device. Background Art

[0004] NAND Flash stores data using different threshold voltages. Over time and due to various environmental factors, the threshold voltage of NAND Flash memory cells can shift. When the threshold voltage shifts, reading data using the default threshold voltage will result in many bit flips, leading to data read errors. Therefore, when the threshold voltage shifts, it's necessary to actively scan the voltage distribution to find the optimal threshold voltage (the lowest point in the voltage distribution). Then, reading data based on this optimal threshold voltage minimizes bit flips and allows the correct data to be read.

[0005] However, due to the large range of threshold voltages, existing voltage distribution scanning methods typically scan the entire threshold voltage range to find the optimal threshold voltage, resulting in low efficiency in obtaining the optimal threshold voltage. Furthermore, if a threshold voltage shifts significantly, it is likely to shift to another threshold voltage range. This presents a problem: if the scanning range is too narrow, it will be impossible to scan the location of the threshold voltage; if the scanning range is expanded, it will be impossible to distinguish the specific threshold voltage.

[0006] Application Contents

[0007] The purpose of this application is to provide a method, apparatus and non-volatile storage device for obtaining an optimal threshold voltage, which can effectively reduce the voltage scanning range and number of times, thereby improving the accuracy and efficiency of obtaining the optimal threshold voltage.

[0008] To achieve the above objectives:

[0009] In a first aspect, the present application provides a method for obtaining an optimal threshold voltage, the method comprising:

[0010] Get target scanning mode and target scanning step size;

[0011] Based on a target scan mode and a target scan step size, a target page in the NAND flash memory is read using at least one scan voltage, and a syndrome value corresponding to each scan voltage is obtained; the syndrome value is generated by decoding the read data;

[0012] An optimal threshold voltage corresponding to the target page is determined according to the syndrome value corresponding to each scan voltage.

[0013] In one embodiment, the target scanning mode includes a dynamic scanning mode; based on the target scanning mode and the target scanning step size, a read operation is performed on a target page in the NAND flash memory using at least one scanning voltage, and a syndrome value corresponding to each scanning voltage is obtained, including:

[0014] Step S10: determining an initial scanning voltage, an initial syndrome value corresponding to the initial scanning voltage, and an initial scanning direction; the scanning direction is used to indicate whether to scan from the left or right side of the initial scanning voltage;

[0015] Step S11: Determine the current scanning voltage V corresponding to the i-th scan in the current scanning direction according to the target scanning step length and the initial scanning voltage. i ;

[0016] Step S12: Based on the current scanning voltage V i Perform a read operation on the target page in the NAND flash memory and decode the read data to obtain the current scan voltage V i The corresponding syndrome value S i ;

[0017] Step S13: According to the current scanning voltage V i The corresponding syndrome value S i , detect the changing trend of syndrome value;

[0018] Step S14: If the trend of the syndrome value is decreasing, control i=i+1 and return to step S11;

[0019] Step S15: If the trend of the syndrome value is increasing, change the current scanning direction and return to step S11.

[0020] In one embodiment, it further includes:

[0021] If the trend of the syndrome value changes from decreasing to increasing, the scan is stopped.

[0022] In one embodiment, step S13 includes:

[0023] Calculate the current scanning voltage V i The corresponding syndrome value S i With the scanning voltage Vi-1 The corresponding syndrome value S i-1 The first average value of the scanning voltage V i-1 The corresponding syndrome value S i-1 With the scanning voltage V i-2 The corresponding syndrome value S i-2 The second mean of

[0024] detecting whether the first average value is greater than the second average value;

[0025] If so, it is determined that the trend of change of the syndrome value is increasing;

[0026] If not, it is determined that the trend of change of the syndrome value is decreasing.

[0027] In one embodiment, the target scanning mode includes a static scanning mode; based on the target scanning mode and the target scanning step size, performing a read operation on a target page in the NAND flash memory using at least one scanning voltage, and obtaining a syndrome value corresponding to each scanning voltage, including:

[0028] Based on the target scan step size, scanning voltages are selected from left to right or from right to left within a preset scan voltage range, and a read operation is performed on a target page in the NAND flash memory based on each selected scan voltage to obtain data read by each scan voltage;

[0029] The data read from each scanning voltage is decoded to obtain a syndrome value corresponding to each scanning voltage.

[0030] In one embodiment, determining the optimal threshold voltage corresponding to the target page based on the syndrome value corresponding to each scan voltage includes at least one of the following:

[0031] determining a target scan voltage corresponding to the minimum syndrome value as an optimal threshold voltage corresponding to the target page;

[0032] An average value of a target scan voltage and adjacent scan voltages of the target scan voltage is obtained, and the average value is determined as an optimal threshold voltage corresponding to the target page.

[0033] In one embodiment, it further includes:

[0034] When a verification error is detected in a read operation on a target page, a step of performing a read operation on the target page in the NAND flash memory by using at least one scan voltage based on a target scan mode and a target scan step is executed.

[0035] In a second aspect, the present application provides a device for obtaining an optimal threshold voltage, comprising:

[0036] An acquisition module is configured to acquire a target scanning mode and a target scanning step size;

[0037] a processing module configured to read target pages in the NAND flash memory using at least one scan voltage based on a target scan mode and a target scan step size, and obtain a syndrome value corresponding to each scan voltage; the syndrome value is generated by decoding the read data;

[0038] The determination module is configured to determine a scan voltage corresponding to a target syndrome value that meets a preset condition as an optimal threshold voltage corresponding to the target page.

[0039] In one embodiment, the target scanning mode includes a dynamic scanning mode; the processing module is configured to:

[0040] Step S10: determining an initial scanning voltage, an initial syndrome value corresponding to the initial scanning voltage, and an initial scanning direction; the scanning direction is used to indicate whether to scan from the left or right side of the initial scanning voltage;

[0041] Step S11: Determine the current scanning voltage V corresponding to the i-th scan in the current scanning direction according to the target scanning step length and the initial scanning voltage. i ;

[0042] Step S12: Based on the current scanning voltage V i Perform a read operation on the target page in the NAND flash memory and decode the read data to obtain the current scan voltage V i The corresponding syndrome value S i ;

[0043] Step S13: According to the current scanning voltage V i The corresponding syndrome value S i , detect the changing trend of syndrome value;

[0044] Step S14: If the trend of the syndrome value is decreasing, control i=i+1 and return to step S11;

[0045] Step S15: If the trend of the syndrome value is increasing, change the current scanning direction and return to step S11.

[0046] In one embodiment, the processing module is configured to:

[0047] If the trend of the syndrome value changes from decreasing to increasing, the scan is stopped.

[0048] In one embodiment, the processing module is configured to:

[0049] Calculate the current scanning voltage V i The corresponding syndrome value S i With the scanning voltage V i-1The corresponding syndrome value S i-1 The first average value of the scanning voltage V i-1 The corresponding syndrome value S i-1 With the scanning voltage V i-2 The corresponding syndrome value S i-2 The second mean of

[0050] detecting whether the first average value is greater than the second average value;

[0051] If so, it is determined that the trend of change of the syndrome value is increasing;

[0052] If not, it is determined that the trend of change of the syndrome value is decreasing.

[0053] In one embodiment, the target scanning mode includes a static scanning mode; the processing module is configured to:

[0054] Based on the target scan step size, scanning voltages are selected from left to right or from right to left within a preset scan voltage range, and a read operation is performed on a target page in the NAND flash memory based on each selected scan voltage to obtain data read by each scan voltage;

[0055] The data read from each scanning voltage is decoded to obtain a syndrome value corresponding to each scanning voltage.

[0056] In one embodiment, the determination module is configured to:

[0057] determining a target scan voltage corresponding to the minimum syndrome value as an optimal threshold voltage corresponding to the target page;

[0058] An average value of a target scan voltage and adjacent scan voltages of the target scan voltage is obtained, and the average value is determined as an optimal threshold voltage corresponding to the target page.

[0059] In one embodiment, the apparatus further comprises a detection module configured to:

[0060] When a verification error is detected in a read operation on a target page, the processing module is triggered to execute a step of performing a read operation on the target page in the NAND flash memory using at least one scan voltage based on a target scan mode and a target scan step size.

[0061] In a third aspect, the present application also provides a non-volatile storage device, which includes: a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the method for obtaining the optimal threshold voltage as in the first aspect are implemented.

[0062] In a fourth aspect, the present application further provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method for obtaining an optimal threshold voltage as in the first aspect.

[0063] Embodiments of the present application provide a method, apparatus, and non-volatile storage device for obtaining an optimal threshold voltage. The method comprises: obtaining a target scan mode and a target scan step size; based on the target scan mode and the target scan step size, performing a read operation on a target page in a NAND flash memory using at least one scan voltage, and obtaining a syndrome value corresponding to each scan voltage; the syndrome value is generated by decoding the read data; and determining the optimal threshold voltage corresponding to the target page based on the syndrome value corresponding to each scan voltage. In this manner, performing a read operation on a target page in the NAND flash memory using at least one scan voltage determined by the target scan mode and the target scan step size, and then selecting the optimal threshold voltage corresponding to the target page based on the syndrome value, effectively reduces the voltage scan range and number of times, thereby improving the efficiency of obtaining the optimal threshold voltage. Furthermore, because the syndrome values ​​generated during the scan process have only a single valley in their distribution, this solves the problem of unrecognizable data due to cross-border threshold voltage offsets, thereby improving the accuracy of obtaining the optimal threshold voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, and unless otherwise stated, the dimensions in the drawings do not constitute proportional limitations.

[0065] FIG1 is a flow chart of a method for obtaining an optimal threshold voltage according to an embodiment of the present application.

[0066] FIG2 is a schematic structural diagram of a device for obtaining an optimal threshold voltage provided in an embodiment of the present application.

[0067] FIG3 is a flow chart of a method for obtaining an optimal threshold voltage in the related art.

[0068] FIG4 is a schematic diagram of VT distribution and syndrome distribution obtained by scanning voltage in an embodiment of the present application.

[0069] Description of reference numerals: DETAILED DESCRIPTION

[0070] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0071] It should be noted that, in this document, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, components, features, and elements with the same name in different embodiments of the present application may have the same meaning or different meanings, and their specific meanings need to be determined by their explanation in the specific embodiment or further combined with the context of the specific embodiment.

[0072] It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this document, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the term "if" as used herein may be interpreted as "at the time of" or "when" or "in response to a determination." Furthermore, as used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms "comprising" and "including" indicate the presence of the described features, steps, operations, elements, components, items, types, and / or groups, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, types, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Thus, “A, B, or C” or “A, B, and / or C” means “any of: A; B; C; A and B; A and C; B and C; A, B, and C.” An exception to this definition occurs only when a combination of elements, functions, steps, or operations are inherently mutually exclusive in some manner.

[0073] It should be understood that, although the various steps in the flowchart in the embodiment of the present application are shown in sequence according to the indication of the arrows, these steps are not necessarily performed in sequence in the order indicated by the arrows. Unless clearly stated herein, the execution of these steps is not strictly limited in order, and they can be performed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times, and their execution order is not necessarily performed in sequence, but can be performed in turn or alternately with at least a portion of other steps or sub-steps or stages of other steps.

[0074] It should be noted that in this article, step codes such as S1 and S2 are used for the purpose of expressing the corresponding content more clearly and concisely, and do not constitute a substantial restriction on the order. When implementing the step, those skilled in the art may execute S2 first and then S1, etc., but these should all be within the scope of protection of this application.

[0075] It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0076] In the subsequent description, the use of suffixes such as "module", "component" or "unit" to represent elements is only for the purpose of facilitating the description of the present application and has no specific meaning. Therefore, "module", "component" or "unit" can be used interchangeably.

[0077] Nand Flash is a non-volatile semiconductor storage medium whose basic storage unit is a double-layer floating-gate MOS transistor similar to an N-type metal oxide semiconductor (NMOS). By applying a positive voltage to the control electrode, electrons can be injected into the floating gate layer. The more electrons injected, the higher the on-state voltage is. Therefore, different storage information can be represented according to different voltage distributions. Conventional Nand Flash is divided into SLC (Single Level Cell), MLC (Multiple Level Cell), TLC (Triple Level Cell) and QLC (Quadruple Level Cell), which store 1 bit, 2 bits, 3 bits and 4 bits of data in a storage unit respectively, and the number of voltage distribution intervals is 2, 4, 8 and 16 respectively.

[0078] During the data storage process, the migration of electronic states will occur, resulting in errors in data reading. For example, read interference will cause the voltage distribution state to shift to the right; electrons escaping over time will cause the electron distribution state to shift to the left. In addition, temperature changes, Nand aging, interference between adjacent units, etc. will cause the migration of the stored data state, causing the single state distribution to become wider or even overlap. After the data storage state is migrated, if the default threshold voltage is still used to read the data, there will be a large number of errors. Therefore, it is usually necessary to find the state distribution after migration and use the trough of the voltage distribution (i.e., the optimal threshold voltage) to read the data. However, when the related technology obtains the optimal threshold voltage based on the trough of the voltage distribution, because the threshold voltage range is relatively large, a large-scale scan is required, which is usually 1-2 orders of magnitude higher than normal reading, so the efficiency is relatively low. In addition, the related technology cannot solve the situation where a certain threshold voltage offset is too large, resulting in it falling into the adjacent threshold voltage interval, because the voltage distribution cannot identify which threshold voltage interval the corresponding trough belongs to.

[0079] Based on this, an embodiment of the present application provides a method for obtaining an optimal threshold voltage. Referring to FIG1 , the method can be performed by a device for obtaining an optimal threshold voltage provided in an embodiment of the present application. The device can be implemented in software and / or hardware. In specific applications, the device can be an electronic device including a non-volatile storage device. The electronic device can be implemented in various forms. The electronic device described in this embodiment can include devices such as mobile phones, tablet computers, laptop computers, PDAs, PMPs, wearable devices, smart bracelets, pedometers, servers, etc. The method for obtaining an optimal threshold voltage provided in this embodiment may include the following steps:

[0080] Step S1: Obtain target scanning mode and target scanning step size.

[0081] The target scanning mode refers to the method for generating the corresponding scanning voltage for performing a page read operation on the NAND flash memory, including a static scanning mode and a dynamic scanning mode. The static scanning mode refers to a method for selecting the scanning voltage in a predetermined order and based on the scanning step size. The dynamic scanning mode refers to a method for adjusting the scanning voltage according to the result generated by performing a page read operation on the NAND flash memory based on the scanning voltage, based on the initial scanning voltage and the scanning step size. In this embodiment, the target scanning mode and target scanning step size can be set according to actual needs. For example, the target scanning mode can be set to a dynamic scanning mode, and the target scanning step size can be set to 1 unit voltage, 2 unit voltages, etc., where 1 unit voltage can be 1mV, 2mV, or other values.

[0082] Step S2: Based on the target scan mode and target scan step size, read the target page in the NAND flash memory using at least one scan voltage, and obtain a syndrome value corresponding to each scan voltage; the syndrome value is generated by decoding the read data.

[0083] Specifically, based on a target scanning mode and a target scanning step size, a read operation is performed on a target page in the NAND flash memory using at least one scanning voltage to obtain data read corresponding to each scanning voltage. For the data read corresponding to each scanning voltage, the data can be decoded accordingly to obtain a syndrome value corresponding to each scanning voltage. The syndrome value can be used to characterize the data quality of the target page read by the scanning voltage.

[0084] Among them, the target page is the page on which the read operation needs to be performed. The target page can be any page of any block (Block) in the NAND flash memory, or it can be a specified page of a block in the NAND flash memory, such as a page where an error occurs in the data reading operation. The data decoding method can be set according to actual needs. In this embodiment, the data decoding can adopt a low-density parity-check code (LDPC) method. It can be understood that before the data is stored in the target page, the data needs to be encoded. Therefore, when reading data from the target page, the read data needs to be decoded accordingly. It should be noted that in this embodiment, the data encoding also adopts a low-density parity-check code method.

[0085] The following briefly describes LDPC decoding, specifically taking quasi-cyclic low-density parity-check code decoding as an example. Quasi-cyclic low-density parity-check code (QC-LDPC) can usually be represented by its parity check matrix, where P i,j is a QC block and an L*L unit circulant matrix. m is the number of rows in the check matrix, n is the number of columns in the check matrix, and the check matrix H is as follows:

[0086] Assume that an LDPC codeword c (which is the encoded data and error-free) passes through a noisy channel. The corresponding received codeword is r = c + e, where r is the data after the codeword c is transmitted through the channel, which may be erroneous. e is the error pattern, which is an abstraction of the channel and indicates the location of the error in the codeword r. S = r × H T , called the syndrome value. T Representing the transpose of H, S has the following properties:

[0087] 1) When S = 0, the transmission is error-free, otherwise the transmission is error-free;

[0088] 2) The larger the S value, the more errors there are, and vice versa;

[0089] 3) When the error is very large, the value of S will be close to m*L / 2.

[0090] The H check matrix is ​​the XOR value of a series of points. When there are many errors, the XOR values ​​of this series of check matrices after 0 / 1 will be relatively equal, and its value will be close to m*L / 2.

[0091] It's understandable that, since LDPC is correctable within a certain error range, the number of error bits after LDPC decoding can be used to assist with voltage scanning. However, threshold voltage scanning often exceeds the error range, rendering the error statistics from LDPC ineffective and limiting its applicability. Combining this with syndrome scanning can address this issue. Furthermore, LDPC decoding can be used to reduce processing time when performing syndrome statistics.

[0092] In one embodiment, the target scanning mode includes a dynamic scanning mode; based on the target scanning mode and the target scanning step size, a read operation is performed on a target page in the NAND flash memory using at least one scanning voltage, and a syndrome value corresponding to each scanning voltage is obtained, including:

[0093] Step S10: determining an initial scanning voltage, an initial syndrome value corresponding to the initial scanning voltage, and an initial scanning direction; the scanning direction is used to indicate whether to scan from the left or right side of the initial scanning voltage;

[0094] Step S11: Determine the current scanning voltage V corresponding to the i-th scan in the current scanning direction according to the target scanning step length and the initial scanning voltage. i ;

[0095] Step S12: Based on the current scanning voltage V i Perform a read operation on the target page in the NAND flash memory and decode the read data to obtain the current scan voltage V i The corresponding syndrome value S i ;

[0096] Step S13: According to the current scanning voltage V i The corresponding syndrome value S i , detect the changing trend of syndrome value;

[0097] Step S14: If the trend of the syndrome value is decreasing, control i=i+1 and return to step S11;

[0098] Step S15: If the trend of the syndrome value is increasing, change the current scanning direction and return to step S11.

[0099] The initial scanning voltage and initial scanning direction can be set based on actual needs. For example, the initial scanning voltage can be set to 0, and the initial scanning direction can be set to the left or right, i.e., scanning starts from the left or right side of the initial scanning voltage. It is understood that after obtaining the syndrome value corresponding to the current scanning voltage, the syndrome value's changing trend can be determined based on the syndrome value corresponding to the current scanning voltage and the syndrome value corresponding to the historical scanning voltage, thereby determining the scanning voltage corresponding to the next scan based on the syndrome value's changing trend. Here, the syndrome value's changing trend can be determined by directly comparing the syndrome values ​​corresponding to two adjacent scanning voltages, or by using the syndrome values ​​corresponding to multiple scanning voltages. Optionally, for each scanning direction, when the number of scans i is less than or equal to a preset number threshold, the syndrome value's changing trend can be omitted to accurately determine the syndrome value's changing trend. The preset number threshold can be set based on actual needs, such as 2 or 3. In this way, the scanning voltage can be selected based on the syndrome value's changing trend, further effectively reducing the voltage scanning range and number of scans, thereby further improving the efficiency of obtaining the optimal threshold voltage.

[0100] In one embodiment, step S13 includes:

[0101] Calculate the current scanning voltage V i The corresponding syndrome value S i With the scanning voltage V i-1 The corresponding syndrome value S i-1 The first average value of the scanning voltage V i-1 The corresponding syndrome value S i-1 With the scanning voltage V i-2 The corresponding syndrome value S i-2 The second mean of

[0102] detecting whether the first average value is greater than the second average value;

[0103] If so, it is determined that the trend of change of the syndrome value is increasing;

[0104] If not, it is determined that the trend of change of the syndrome value is decreasing.

[0105] It is understood that, considering the influence of voltage and / or syndrome value fluctuation, the trend of syndrome value change can be determined based on the current syndrome value and the syndrome values ​​corresponding to the last two scans. Specifically, the current scan voltage V i The corresponding syndrome value S iThe scanning voltage V of the i-1th scanning i-1 The corresponding syndrome value S i-1 The first average value of , and the scanning voltage V of the i-1th scanning i-1 The corresponding syndrome value S i-1 The syndrome value S corresponding to the scanning voltage of the i-2th scanning i-2 The second average value is then compared to see whether the first average value is greater than the second average value. If so, it means that the syndrome value is gradually increasing, that is, the trend of the syndrome value is increasing; if not, it means that the syndrome value is gradually decreasing, that is, the trend of the syndrome value is decreasing. It should be noted that the current scanning voltage V i , scanning voltage V i-1 and the scanning voltage V i-2 In this way, the trend of the syndrome value can be accurately judged, and the accuracy of the optimal threshold voltage can be improved.

[0106] In one embodiment, the method further comprises:

[0107] If the trend of the syndrome value changes from decreasing to increasing, the scan is stopped.

[0108] It can be understood that since the data quality of the target page read through the optimal threshold voltage is the best, that is, the companion value corresponding to the optimal threshold voltage is usually relatively small, therefore, after the trend of change of the companion value gradually decreases for a period of time, if the trend of change of the companion value changes from decreasing to increasing, it means that the target page in the NAND flash memory has been read through the optimal threshold voltage, then the scanning can be stopped, thereby further reducing the voltage scanning range and number of times, and further improving the efficiency of obtaining the optimal threshold voltage.

[0109] The following example illustrates the scanning process, taking the initial scanning voltage as V0, the initial syndrome value as S0, the target scanning step size as N, and the initial scanning direction as the right side, i.e., selecting the scanning voltage from the right side of the initial scanning voltage V0:

[0110] For the first scan on the right side, the corresponding current scan voltage V1 is V0+N. A read operation is performed on the target page in the NAND flash memory based on the current scan voltage V1, and the read data is decoded to obtain the syndrome value S1 corresponding to the current scan voltage V1. At this point, the syndrome value trend is not determined. For the second scan on the right side, the corresponding current scan voltage V2 is V0+2N. A read operation is performed on the target page in the NAND flash memory based on the current scan voltage V2, and the read data is decoded to obtain the syndrome value S2 corresponding to the current scan voltage V2. If the average value of S2 and S1 is less than or equal to the average value of S1 and S0, the third scan on the right side is executed. If the average value of S2 and S1 is greater than the average value of S1 and S0, the right scan is terminated and the first scan on the left side is executed. For the third scan on the right side, the corresponding current scan voltage V3 is V0+3N. Then, a read operation is performed on the target page in the NAND flash memory based on the current scan voltage V3, and the read data is decoded to obtain the syndrome value S3 corresponding to the current scan voltage V3; if the average value of S3 and S2 is less than or equal to the average value of S2 and S1, the fourth scan on the right side is performed, and the specific details can be referred to the above scanning process, until the trend of the syndrome value is increasing; if the average value of S3 and S2 is greater than the average value of S2 and S1, the right scan is stopped and the first scan on the left side is performed.

[0111] For the first scan on the left, the corresponding current scan voltage V1 is V0+N. A read operation is performed on the target page in the NAND flash memory based on the current scan voltage V1, and the read data is decoded to obtain the syndrome value S1 corresponding to the current scan voltage V1. At this point, the syndrome value trend is not determined. For the second scan on the left, the corresponding current scan voltage V2 is V0+2N. A read operation is performed on the target page in the NAND flash memory based on the current scan voltage V2, and the read data is decoded to obtain the syndrome value S2 corresponding to the current scan voltage V2. If the average value of S2 and S1 is less than or equal to the average value of S1 and S0, the third scan on the left is performed. If the average value of S2 and S1 is greater than the average value of S1 and S0, the scan is terminated. For the third scan on the left, the corresponding current scan voltage V3 is V0+3N. Then, a read operation is performed on the target page in the NAND flash memory based on the current scan voltage V3, and the read data is decoded to obtain the syndrome value S3 corresponding to the current scan voltage V3; if the average value of S3 and S2 is less than or equal to the average value of S2 and S1, the fourth scan on the left is performed. For details, please refer to the above scanning process, and the scan is stopped until the trend of the syndrome value increases; if the average value of S3 and S2 is greater than the average value of S2 and S1, the scan is stopped.

[0112] In one embodiment, the target scanning mode includes a static scanning mode; based on the target scanning mode and the target scanning step size, performing a read operation on a target page in the NAND flash memory using at least one scanning voltage, and obtaining a syndrome value corresponding to each scanning voltage, including:

[0113] Based on the target scan step size, scanning voltages are selected from left to right or from right to left within a preset scan voltage range, and a read operation is performed on a target page in the NAND flash memory based on each selected scan voltage to obtain data read by each scan voltage;

[0114] The data read from each scanning voltage is decoded to obtain a syndrome value corresponding to each scanning voltage.

[0115] Specifically, based on the target scan step length, multiple scan voltages are selected in sequence from left to right or from right to left within a preset scan voltage range, the difference between two adjacent scan voltages is the target scan step length, and a read operation is performed on the target page in the NAND flash memory based on each selected scan voltage to obtain data read by each scan voltage. At the same time, the data read by each scan voltage is decoded to obtain the syndrome value corresponding to each scan voltage.

[0116] It can be understood that, assuming that the preset scanning voltage range is [-S, S), and only includes voltages of positive integers, when the target scanning step size is 1 unit voltage (such as 1mV), 2S scanning voltages need to be selected, that is, 2S scans are required; when the target scanning step size is 2 unit voltages (such as 2mV), S scanning voltages need to be selected, that is, S scans are required, and so on. It should be noted that the preset scanning voltage range can be set according to actual needs, for example, it can be set to be greater than the interval between two threshold voltages in the NAND flash memory. In this way, a scanning voltage within the preset scanning voltage range can be selected according to the scanning step size, further reducing the voltage scanning range and number of times, thereby further improving the efficiency of obtaining the optimal threshold voltage.

[0117] Step S3: determining the optimal threshold voltage corresponding to the target page according to the syndrome value corresponding to each scan voltage.

[0118] It can be understood that since the syndrome value can be used to characterize the data quality of the target page read by the scan voltage, that is, the syndrome value corresponding to different scan voltages can be used to determine the data quality of the target page read by different scan voltages, the optimal threshold voltage corresponding to the target page can be determined based on the syndrome value corresponding to each scan voltage to achieve accurate data reading. It should be noted that the optimal threshold voltage corresponding to the target page can also be used as the optimal threshold voltage for other pages in the block where the target page is located.

[0119] In one embodiment, determining the optimal threshold voltage corresponding to the target page based on the syndrome value corresponding to each scan voltage includes at least one of the following:

[0120] determining a target scan voltage corresponding to the minimum syndrome value as an optimal threshold voltage corresponding to the target page;

[0121] An average value of a target scan voltage and adjacent scan voltages of the target scan voltage is obtained, and the average value is determined as an optimal threshold voltage corresponding to the target page.

[0122] For the syndrome values ​​corresponding to each scan voltage obtained by selecting scan voltages using a static scan mode or a dynamic scan mode, the syndrome values ​​corresponding to each scan voltage can be compared, and the target scan voltage corresponding to the minimum syndrome value can be determined as the optimal threshold voltage corresponding to the target page. Alternatively, after determining the target scan voltage, the average of the target scan voltage and adjacent scan voltages can be determined as the optimal threshold voltage corresponding to the target page, thereby reducing the impact of fluctuations and further improving data reading accuracy. Adjacent scan voltages to the target scan voltage can include at least one scan voltage located to the left and / or right of the target scan voltage, and the difference between the target scan voltage and the target scan voltage can be one or more target scan step sizes.

[0123] In summary, the method for obtaining the optimal threshold voltage provided in the above-described embodiment performs a read operation on a target page in the NAND flash memory using at least one scan voltage determined by a target scan mode and a target scan step size, and then selects the optimal threshold voltage corresponding to the target page based on the syndrome value. This effectively reduces the voltage scan range and number of scans, thereby improving the efficiency of obtaining the optimal threshold voltage. Furthermore, because the syndrome values ​​generated during the scan have a single valley in their distribution, this solves the problem of unrecognizable data due to cross-border threshold voltage offsets, thereby improving the accuracy of obtaining the optimal threshold voltage.

[0124] In one embodiment, the method further comprises:

[0125] When a verification error is detected in a read operation on a target page, a step of performing a read operation on the target page in the NAND flash memory by using at least one scan voltage based on a target scan mode and a target scan step is executed.

[0126] It is understood that when a verification error occurs during a read operation on a target page, it indicates that the threshold voltage used for the read operation on the target page is inaccurate. To obtain the optimal threshold voltage, a read operation can be performed on the target page in the NAND flash memory using at least one scan voltage based on a target scan mode and a target scan step size to obtain the optimal threshold voltage corresponding to the target page. In this way, the step of performing a read operation on the target page in the NAND flash memory using different scan voltages can be performed only when necessary, effectively saving resource consumption.

[0127] Based on the same inventive concept as the above embodiments, referring to FIG2 , an embodiment of the present application provides a device for obtaining an optimal threshold voltage, comprising:

[0128] An acquisition module 201 is configured to acquire a target scanning mode and a target scanning step size;

[0129] The processing module 202 is configured to read target pages in the NAND flash memory using at least one scan voltage based on a target scan mode and a target scan step size, and obtain a syndrome value corresponding to each scan voltage; the syndrome value is generated by decoding the read data;

[0130] The determination module 203 is configured to determine the scan voltage corresponding to the target syndrome value that meets a preset condition as the optimal threshold voltage corresponding to the target page.

[0131] In summary, the apparatus for obtaining an optimal threshold voltage provided by the above-described embodiments performs a read operation on a target page of a NAND flash memory using at least one scan voltage determined by a target scan mode and a target scan step size, and then selects the optimal threshold voltage corresponding to the target page based on the syndrome value. This effectively reduces the voltage scan range and number of scans, thereby improving the efficiency of obtaining the optimal threshold voltage. Furthermore, because the syndrome values ​​generated during the scan have a single valley in their distribution, this solves the problem of unrecognizable data due to cross-border threshold voltage offsets, thereby improving the accuracy of obtaining the optimal threshold voltage.

[0132] In one embodiment, the target scanning mode includes a dynamic scanning mode; the processing module 202 is configured to:

[0133] Step S10: determining an initial scanning voltage, an initial syndrome value corresponding to the initial scanning voltage, and an initial scanning direction; the scanning direction is used to indicate whether to scan from the left or right side of the initial scanning voltage;

[0134] Step S11: Determine the current scanning voltage V corresponding to the i-th scan in the current scanning direction according to the target scanning step length and the initial scanning voltage. i ;

[0135] Step S12: Based on the current scanning voltage Vi Perform a read operation on the target page in the NAND flash memory and decode the read data to obtain the syndrome value S corresponding to the current scan voltage Vi i ;

[0136] Step S13: According to the current scanning voltage V i The corresponding syndrome value S i , detect the changing trend of syndrome value;

[0137] Step S14: If the trend of the syndrome value is decreasing, control i=i+1 and return to step S11;

[0138] Step S15: If the trend of the syndrome value is increasing, change the current scanning direction and return to step S11.

[0139] In this way, it is possible to select the scanning voltage according to the variation trend of the syndrome value, further effectively reducing the voltage scanning range and number, thereby further improving the efficiency of obtaining the optimal threshold voltage.

[0140] In one embodiment, the processing module 202 is configured to:

[0141] If the trend of the syndrome value changes from decreasing to increasing, the scan is stopped.

[0142] In one embodiment, the processing module 202 is configured to:

[0143] Calculate the current scanning voltage V i The corresponding syndrome value S i With the scanning voltage V i-1 The corresponding syndrome value S i-1 The first average value of the scanning voltage V i-1 The corresponding syndrome value S i-1 With the scanning voltage S i-2 The corresponding syndrome value S i-2 The second mean of

[0144] detecting whether the first average value is greater than the second average value;

[0145] If so, it is determined that the trend of change of the syndrome value is increasing;

[0146] If not, it is determined that the trend of change of the syndrome value is decreasing.

[0147] In this way, the changing trend of the syndrome value can be effectively and accurately determined, thereby improving the accuracy of obtaining the optimal threshold voltage.

[0148] In one embodiment, the target scanning mode includes a static scanning mode; the processing module 202 is configured to:

[0149] Based on the target scan step size, scanning voltages are selected from left to right or from right to left within a preset scan voltage range, and a read operation is performed on a target page in the NAND flash memory based on each selected scan voltage to obtain data read by each scan voltage;

[0150] The data read from each scanning voltage is decoded to obtain a syndrome value corresponding to each scanning voltage.

[0151] In this way, a scan voltage within a preset scan voltage range can be selected according to the scan step length, further reducing the voltage scan range and number of times, thereby further improving the efficiency of obtaining the optimal threshold voltage.

[0152] In one embodiment, the determination module 203 is configured to:

[0153] determining a target scan voltage corresponding to the minimum syndrome value as an optimal threshold voltage corresponding to the target page;

[0154] An average value of a target scan voltage and adjacent scan voltages of the target scan voltage is obtained, and the average value is determined as an optimal threshold voltage corresponding to the target page.

[0155] In one embodiment, the apparatus further comprises a detection module configured to:

[0156] When a verification error is detected during a read operation on a target page, the processing module 202 is triggered to execute a step of performing a read operation on the target page in the NAND flash memory using at least one scan voltage based on a target scan mode and a target scan step size.

[0157] In this way, the step of performing a read operation on a target page in the NAND flash memory using different scan voltages can be performed only when needed, which can effectively save resource consumption.

[0158] Based on the same inventive concept as the above embodiments, the above embodiments are described in detail below through a specific example.

[0159] 3 , which shows a method for obtaining an optimal threshold voltage in the related art, including the following steps:

[0160] Step S101: determining that a data error occurs when reading data;

[0161] Step S102: obtaining an optimal threshold voltage through voltage shift;

[0162] Step S103: setting the optimal threshold voltage and re-reading the data;

[0163] Step S104: Check whether there is a data error. If so, execute step S105; otherwise, execute step S106.

[0164] Step S105: Determine whether data reading fails.

[0165] Step S106: Determine whether the data reading is successful.

[0166] However, in order to obtain the optimal threshold voltage, the related art requires voltage scanning (i.e., voltage offset) to obtain a voltage distribution diagram, and then calculate the location of the valley based on the voltage (VT) distribution. The location of this valley is the location of the optimal threshold voltage. However, the above method has two shortcomings:

[0167] 1) Extremely low efficiency. The maximum voltage offset range for mainstream NAND Flash is currently [-127, 127]. For typical TLC Flash, a voltage range typically exceeds several dozen offsets. Specifically, voltage scanning is typically implemented by setting a voltage scan range, such as from 30° left to 30° right. This requires 60 voltage scans, meaning 60 NAND reads, which takes a very long time.

[0168] 2) If a threshold voltage shifts significantly, it is likely to shift to the range where another threshold voltage is located. This will cause a problem: if the voltage scanning range is too narrow, there is no way to scan the location of the threshold voltage; if the voltage scanning range is expanded, there is no way to distinguish which specific threshold voltage is located.

[0169] In other words, in related technologies, if the optimal threshold voltage is obtained based on the troughs of the voltage distribution, the efficiency will be relatively low because the threshold voltage range is relatively large and a large range scan is required, which is usually 1-2 orders of magnitude higher than normal reading. Moreover, it cannot solve the problem of a threshold voltage shifting too much, causing it to fall into an adjacent threshold voltage range, because the voltage distribution cannot identify which threshold voltage the corresponding trough belongs to.

[0170] Based on this, this embodiment proposes a method that no longer relies on voltage distribution to obtain the optimal threshold voltage, but instead relies on the LDPC syndrome value. Specifically, after reading data based on a certain voltage offset and decoding it with the LDPC decoder, the LDPC decoder generates a syndrome value to evaluate data quality. The lower the data bit flip rate, the smaller the syndrome value. This allows scanning across different voltage offsets, and finding the voltage offset with the smallest syndrome value is the optimal threshold voltage.

[0171] It is understandable that, because the syndrome value can indicate the information about the accuracy of the data, it is only necessary to find the offset voltage with the smallest syndrome value, and the syndrome values ​​on the left and right sides of the minimum offset voltage tend to increase, so there is no need to scan the entire voltage range. In other words, there is no need to perform voltage scanning over a large range, which can greatly reduce the range and number of scanned voltages. Refer to Figure 4, which shows the VT distribution and syndrome (accompanying value) distribution obtained by scanning the voltage. The vertical axis on the right side of Figure 4 represents the VT distribution. In order to facilitate the understanding of the VT distribution and syndrome distribution, the scanning range is relatively large, spanning several threshold voltages on the left and right. In Figure 4, the read operation is based on voltage C. Usually, obtaining the threshold voltage is to find the trough of VT. From Figure 4, it can be seen that when the single scanning range is relatively large, VT will scan multiple troughs, but the syndrome distribution has only one trough, so there will be no situation of finding the wrong trough.

[0172] The following describes two methods of obtaining the optimal threshold voltage through syndrome, namely, a static scanning method and a dynamic scanning method.

[0173] (1) Static scanning method

[0174] The static scan method uses a fixed scan range, which is usually slightly longer than the interval between two threshold voltages in NAND. The interval between two threshold voltages in NAND is measurable, and the test method can be to scan the voltage. For example, if you need to obtain the interval between threshold voltages B and C, you can scan left and right based on threshold voltage B. The interval between the trough of threshold voltage B and the first trough to the right of threshold voltage B can be considered the interval between threshold voltages B and C.

[0175] Specifically, set the scan range to [-S, S), and assume the scan step size is 1 unit voltage (e.g., 1 mV). This results in a total of 2S scans, resulting in a syndrome distribution similar to Figure 4. The voltage corresponding to the minimum position in the syndrome is the optimal threshold voltage. Alternatively, after 2S scans, an array of syndrome values ​​is obtained, and the voltage corresponding to the minimum value is the optimal threshold voltage.

[0176] (2) Dynamic scanning method

[0177] The dynamic scanning method reduces the scanning range by actively detecting the valley characteristics. Before scanning the optimal threshold voltage, it is necessary to set a starting offset voltage, that is, the initial scanning voltage, which can generally be set to 0. In addition, a scanning step size is also set, which is defined as N. The specific scanning process is as follows:

[0178] (1) Usually, the optimal threshold voltage can be found starting from the initial scan voltage, and data is read based on the initial scan voltage, and the LDPC syndrome value is recorded as S0.

[0179] (2) Start the i-th scan to the left, the offset voltage, i.e. the scan voltage, is -(i*N), and record the corresponding syndrome value S i Each time you scan, determine the syndrome value's changing trend. If the syndrome value shows an increasing trend, it means the optimal threshold voltage is not on the left side. End the left scan and start the right scan. If the syndrome value's changing trend is decreasing, it means the optimal threshold voltage is on the left side. Continue scanning the left side until the syndrome value's changing trend begins to increase.

[0180] (3) The right scanning method is similar to the left scanning method. The jth scan starts from the right side, and the offset voltage is j*N. When the trend of the syndrome value is increasing, the scan is stopped.

[0181] Here, regarding the condition for stopping the scan, that is, the trend of the syndrome value change, we can consider using the average of the two most recent syndrome values ​​to reduce the impact of some fluctuations. For example, the syndrome values ​​obtained by scanning are S0, S1, S2, ..., S i-1 , S i , when (S i +S i-1 ) / 2>(S i-1 +S i-2 ) / 2, it can be considered that the trend of change is increasing, otherwise it means that the trend of change is decreasing.

[0182] (4) The total scanning range is -(i*N) to j*N, and the best value is taken from the i+j+1 syndrome values. The voltage corresponding to the best value is the optimal threshold voltage.

[0183] Here, the optimal value may be the minimum syndrome value, or may be determined based on an average value, such as selecting the average value of a plurality of minimum syndrome values.

[0184] In summary, the method for obtaining the optimal threshold voltage provided in the above embodiment uses the LDPC syndrome value to obtain the optimal threshold voltage based on static scanning and dynamic scanning methods, which can reduce the voltage scanning range and number, thereby improving the efficiency of obtaining the optimal threshold voltage; at the same time, it can solve the problem of multiple threshold voltage offsets crossing the boundary and causing unrecognition.

[0185] An embodiment of the present application also provides a non-volatile storage device, which includes: a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of any of the above-mentioned methods for obtaining the optimal threshold voltage are implemented.

[0186] An embodiment of the present application further provides a storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of any of the above-described methods for obtaining an optimal threshold voltage are implemented.

[0187] In the embodiments of the electronic device and storage medium provided in the embodiments of the present application, all technical features of any of the above-mentioned processing method embodiments may be included. The expanded and explained contents of the specification are basically the same as those of the embodiments of the above-mentioned methods and will not be repeated here.

[0188] An embodiment of the present application further provides a computer program product, which includes computer program code. When the computer program code runs on a computer, the computer executes the method for obtaining the optimal threshold voltage in the various possible implementations described above.

[0189] An embodiment of the present application also provides a chip, including a memory and a processor, wherein the memory is used to store computer programs, and the processor is used to call and run the computer programs from the memory, so that a device equipped with the chip executes the method for obtaining the optimal threshold voltage in various possible implementations as described above.

[0190] It is understood that the above scenarios are merely examples and do not limit the application scenarios of the technical solutions provided in the embodiments of this application. The technical solutions of this application can also be applied to other scenarios. For example, those skilled in the art will appreciate that with the evolution of system architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application will also be applicable to similar technical problems.

[0191] The serial numbers of the above embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0192] The steps in the method of the embodiment of the present application can be adjusted in order, combined and deleted according to actual needs.

[0193] The units in the device of the embodiment of the present application can be merged, divided and deleted according to actual needs.

[0194] In this application, the same or similar terminology, technical solutions and / or application scenario descriptions are generally only described in detail the first time they appear. When they appear again later, they are generally not repeated for the sake of brevity. When understanding the technical solutions and other contents of this application, for the same or similar terminology, technical solutions and / or application scenario descriptions that are not described in detail later, you can refer to the previous relevant detailed descriptions.

[0195] In this application, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0196] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0197] As used herein, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion of elements other than the listed elements and may also include additional elements not specifically listed.

[0198] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for obtaining an optimal threshold voltage, characterized in that: The method comprises: Obtain target scanning mode and target scanning step size; Based on the target scanning mode and the target scanning step length, a target page in the NAND flash memory is read by at least one scanning voltage, and a syndrome value corresponding to each scanning voltage is obtained; the syndrome value is generated by decoding the read data; The optimal threshold voltage corresponding to the target page is determined according to the syndrome value corresponding to each scan voltage.

2. The method according to claim 1, characterized in that The target scanning mode includes a dynamic scanning mode; based on the target scanning mode and the target scanning step length, performing a read operation on a target page in the NAND flash memory by using at least one scanning voltage, and obtaining a syndrome value corresponding to each scanning voltage, including: Step S10, determining an initial scanning voltage, an initial syndrome value corresponding to the initial scanning voltage, and an initial scanning direction; the initial scanning direction is used to indicate scanning from the left side or the right side of the initial scanning voltage; Step S11: Determine the current scanning voltage V corresponding to the i-th scanning in the current scanning direction according to the target scanning step length and the initial scanning voltage. i ; Step S12: based on the current scanning voltage S i A read operation is performed on the target page in the NAND flash memory, and the read data is decoded to obtain the current scan voltage S i The corresponding syndrome value S i ; Step S13: according to the current scanning voltage S i The corresponding syndrome value S i , detect the changing trend of syndrome value; Step S14: If the trend of the syndrome value is decreasing, control i=i+1 and return to step S11; Step S15: If the trend of the syndrome value is increasing, change the current scanning direction and return to step S11.

3. The method according to claim 2, characterized in that Also includes: If the trend of the syndrome value changes from decreasing to increasing, the scan is stopped.

4. The method according to claim 2, characterized in that: The step S13 comprises: Calculate the current scan voltage V i The corresponding syndrome value S i With the scanning voltage V i-1 The corresponding syndrome value S i-1 The first average value of the scanning voltage V i-1 The corresponding syndrome value S i-1 With the scanning voltage V i-2 The corresponding syndrome value S i-2 The second mean of detecting whether the first average value is greater than the second average value; If so, it is determined that the trend of the syndrome value is increasing; If not, it is determined that the trend of the syndrome value is decreasing.

5. The method according to claim 1, characterized in that The target scanning mode includes a static scanning mode; based on the target scanning mode and the target scanning step length, performing a read operation on a target page in the NAND flash memory by using at least one scanning voltage, and obtaining a syndrome value corresponding to each scanning voltage, including: Based on the target scan step length, traversing and selecting scan voltages from left to right or from right to left within a preset scan voltage range, and performing a read operation on a target page in the NAND flash memory based on each selected scan voltage to obtain data read by each scan voltage; The data read from each scanning voltage is decoded to obtain a syndrome value corresponding to each scanning voltage.

6. The method according to any one of claims 1 to 5, characterized in that The determining the optimal threshold voltage corresponding to the target page according to the syndrome value corresponding to each scan voltage includes at least one of the following: Determining a target scan voltage corresponding to the minimum syndrome value as an optimal threshold voltage corresponding to the target page; An average value of the target scan voltage and scan voltages adjacent to the target scan voltage is obtained, and the average value is determined as an optimal threshold voltage corresponding to the target page.

7. The method according to any one of claims 1 to 5, characterized in that Also includes: When a verification error is detected in the read operation on the target page, the step of performing a read operation on the target page in the NAND flash memory by using at least one scan voltage based on the target scan mode and the target scan step is executed.

8. A device for obtaining an optimal threshold voltage, characterized in that: include: An acquisition module is configured to acquire a target scanning mode and a target scanning step size; A processing module is configured to perform a read operation on a target page in the NAND flash memory by at least one scan voltage based on the target scan mode and the target scan step size, and obtain a syndrome value corresponding to each scan voltage; the syndrome value is generated by decoding the read data; The determination module is configured to determine the scan voltage corresponding to the target syndrome value that meets the preset condition as the optimal threshold voltage corresponding to the target page.

9. A non-volatile storage device, characterized in that: include: A processor and a memory storing a computer program, wherein when the processor runs the computer program, the steps of the method for obtaining an optimal threshold voltage according to any one of claims 1 to 7 are implemented.

10. A storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the steps of the method for obtaining an optimal threshold voltage according to any one of claims 1 to 7 are implemented.

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