A method for screening flash memory with wide temperature range and storage medium

Abstract

A method for screening flash memory for wide temperature and a storage medium, comprising: performing wide temperature screening on original particles, dividing the original particles into test samples with multiple read error bit thresholds; obtaining an initial yield of the test samples based on the test samples with multiple read error bit thresholds; performing full disk wear processing on the test samples, and when the number of full disk wears reaches a first specified wear number, performing a first wide temperature verification on the test samples to obtain a first yield of the test samples; when the number of full disk wears reaches a second specified wear number, performing a second wide temperature verification on the test samples to obtain a second yield of the test samples; when the number of full disk wears reaches a third specified wear number, performing a third wide temperature verification on the test samples to obtain a third yield of the test samples; and selecting a specified read error bit threshold as an indicator for wide temperature screening based on the initial yield, the first yield, the second yield, and the third yield, and performing wide temperature screening on subsequent original particles based on the indicator.

Description

Technical Field

[0001] The present invention relates to the field of storage technology, and in particular to a method for screening a flash memory with a wide temperature range and a storage medium. Background Art

[0002] With the development of Nand flash memory technology, the application scope of Nand flash memory particles is becoming increasingly broad. Nand flash memory particles have different operating temperature ranges in different application scenarios. Depending on the application scenario, they are generally divided into consumer-grade, industrial-grade, automotive-grade, and military-grade. Consumer-grade particles generally have an operating temperature range of 0-70°C, while industrial-grade particles have a wide operating temperature range of -40°C to 85°C. During use, some particles provided by the original flash memory manufacturer have been found to be of higher quality. Therefore, a screening solution is needed to select original particles that meet industrial-grade standards. This allows original particles to be used in different scenarios (consumer-grade and industrial-grade). This not only ensures their reliability, but also expands the product line and allows the advantages of high-quality particles to be fully utilized.

[0003] Current screening methods typically perform Erase, Program, and Read operations on each memory block of a memory chip in sequence at a constant temperature. The success or failure of each operation determines whether the block is bad, completing the screening of all memory blocks. These methods are unable to identify flash memory that meets wide-temperature standards throughout its lifecycle. Summary of the Invention

[0004] The Summary of the Invention introduces a series of simplified concepts that will be further described in the Detailed Description of the Invention. The Summary of the Invention is not intended to limit the key features and essential features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0005] In response to the current problems, according to one aspect of the present application, a method for screening flash memory with a wide temperature range is provided, the method comprising:

[0006] Providing original particles, performing wide temperature screening on the original particles to obtain read error bits of the original particles, and dividing the original particles into test samples with multiple read error bit thresholds based on the read error bits;

[0007] Obtaining an initial yield of the test sample according to a plurality of test samples having read error bit thresholds;

[0008] Performing a full-disc wear treatment on the test sample, and counting the number of full-disc wears in real time;

[0009] When the number of times the entire disk is worn reaches a first specified number of times, performing a first wide temperature verification on the test sample to obtain a first yield of the test sample;

[0010] When the number of times the entire disk is worn reaches a second specified number of times, performing a second wide temperature verification on the test sample to obtain a second yield of the test sample;

[0011] When the number of times the entire disk is worn reaches a third specified number of times, performing a third wide temperature verification on the test sample to obtain a third yield of the test sample;

[0012] According to the initial yield, the first yield, the second yield, and the third yield, a designated read error bit threshold is selected as an indicator for wide temperature screening, and subsequent original particles are screened at a wide temperature according to the indicator.

[0013] In one embodiment of the present application, dividing the original chips into test samples with multiple read error bit thresholds according to the read error bits includes:

[0014] Through wide temperature screening, original particles with different read error bit thresholds are screened out, and the same number of test samples are screened out from original particles with each read error bit threshold to obtain test samples with multiple read error bit thresholds.

[0015] In one embodiment of the present application, obtaining the initial yield of the test sample according to the test sample having multiple read error bit thresholds includes:

[0016] The initial yield of the test samples is obtained according to the number of original chips required for each read error bit threshold and the number of test samples for each read error bit threshold that pass the wide temperature screening.

[0017] In one embodiment of the present application, the wide temperature screening includes stage one, stage two, and stage three. The wide temperature screening of the original particles includes:

[0018] Dividing the original particles into original bad blocks and original good blocks, and recording the original bad blocks in an original bad block table;

[0019] In the first stage, a first test is performed on the original good blocks to obtain the first stage bad blocks and the first stage good blocks, and the first stage bad blocks are recorded in the first bad block table;

[0020] In the second stage, a second test is performed on the good blocks in the first stage to obtain bad blocks and good blocks in the second stage, and the bad blocks in the second stage are recorded in the second bad block table;

[0021] In the third stage, a third test is performed on the good blocks in the second stage to obtain bad blocks and good blocks in the third stage, and the bad blocks in the third stage are recorded in the bad block table 3;

[0022] When the number of bad blocks in the original bad block table, the bad block table 1, the bad block table 2, and the bad block table 3 is less than the specified number, the original particles pass the wide temperature screening; otherwise, the original particles fail the wide temperature screening.

[0023] In one embodiment of the present application, the first wide temperature verification includes a desired number of wide temperature verifications, and when the number of full disk wear reaches a first specified number of wears, performing the first wide temperature verification on the test sample to obtain a first yield of the test sample includes:

[0024] The test sample is subjected to a desired number of wide temperature verifications. If the desired number of wide temperature verifications are passed, the test sample passes the first wide temperature verification. Otherwise, the test sample fails the first wide temperature verification.

[0025] The first yield of the test samples of each read error bit threshold is calculated by comparing the number of test samples of each read error bit threshold before full disk wear and the number of test samples of each read error bit threshold that pass the first wide temperature verification.

[0026] In one embodiment of the present application, the screening method further comprises the following steps:

[0027] Test samples that fail the first wide temperature verification will not undergo the second wide temperature verification;

[0028] The test sample that passed the first wide temperature verification is subjected to full disk wear. When the number of full disk wear reaches a second specified wear number, the test sample that passed the first wide temperature verification is subjected to a second wide temperature verification.

[0029] In one embodiment of the present application, the second wide temperature verification includes a desired number of wide temperature verifications, and when the number of full disk wear reaches a second specified number of wears, performing the second wide temperature verification on the test sample to obtain a second yield of the test sample includes:

[0030] The test sample is subjected to a desired number of wide temperature verifications. If the desired number of wide temperature verifications are passed, the test sample passes the second wide temperature verification. Otherwise, the test sample fails the second wide temperature verification.

[0031] The second yield of the test samples for each read error bit threshold is calculated by comparing the number of test samples for each read error bit threshold before full disk wear and the number of test samples for each read error bit threshold that pass the second wide temperature verification.

[0032] In one embodiment of the present application, the screening method further comprises the following steps:

[0033] Test samples that fail the second wide temperature verification will not undergo the third wide temperature verification;

[0034] The test sample that passed the second wide temperature verification is subjected to full disk wear. When the number of full disk wear reaches a third specified wear number, the test sample that passed the second wide temperature verification is subjected to a third wide temperature verification.

[0035] In one embodiment of the present application, the third wide temperature verification includes a desired number of wide temperature verifications, and when the number of full disk wear reaches a third specified number of wears, performing the third wide temperature verification on the test sample to obtain a third yield of the test sample includes:

[0036] The test sample is subjected to a desired number of wide temperature verifications. If the desired number of wide temperature verifications are passed, the test sample passes the third wide temperature verification. Otherwise, the test sample fails the third wide temperature verification.

[0037] A third yield of the test samples at each read error bit threshold is calculated based on the number of test samples at each read error bit threshold before full disk wear and the number of test samples at each read error bit threshold that pass the third wide temperature verification.

[0038] According to another aspect of the present application, a storage medium is provided, wherein the storage medium stores a computer program, and when the computer program is executed by a processor, the processor implements the above-mentioned method for screening a wide temperature range of a flash memory.

[0039] According to the wide-temperature screening method and storage medium for flash memory provided by the present invention, wide-temperature screening is performed on original particles, and the original particles are divided into test samples with multiple read error bit thresholds according to the different read error bits of the original particles. The initial yield of the test samples is obtained based on the test samples with multiple read error bit thresholds, and the test samples are subjected to full disk wear. At different wear stages, wide-temperature verification is performed on the test samples and the yield is obtained. According to the yield and initial yield of the test samples with multiple read error bit thresholds at different wear stages, a specified read error bit threshold is selected as an indicator for wide-temperature screening, and subsequent original particles are subjected to wide-temperature screening based on the indicator. The specified read error bit threshold determined by this method is used as a screening indicator for subsequent wide-temperature screening in the factory, and the particles screened out according to this screening indicator have the highest yield throughout their entire life cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and other purposes, features, and advantages of the present application will become more apparent through a more detailed description of the embodiments of the present application in conjunction with the accompanying drawings. The accompanying drawings are intended to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the drawings, the same reference numerals generally represent the same components or steps.

[0041] Figure 1A schematic flow chart showing a method for screening a flash memory with a wide temperature range according to an embodiment of the present invention is shown;

[0042] Figure 2 A schematic flow chart of wide-temperature screening of raw particles according to an embodiment of the present invention is shown;

[0043] Figure 3 A curve diagram of the estimated yield rate change in the early life span according to an embodiment of the present invention is shown;

[0044] Figure 4 A graph showing a change curve of the estimated yield rate at the end of life according to an embodiment of the present invention is shown;

[0045] Figure 5 A structural block diagram of a storage medium according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0046] In the following description, numerous specific details are provided to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without one or more of these details. In other instances, certain technical features well known in the art are not described to avoid confusion with the present invention.

[0047] It should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make the disclosure thorough and complete and to fully convey the scope of the invention to those skilled in the art. In the drawings, the dimensions and relative sizes of layers and regions may be exaggerated for clarity. Like reference numerals throughout represent like elements.

[0048] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present invention. When used herein, the singular forms "a", "an", and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0049] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application relates. It will also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with their meaning in the context of the relevant art and / or this specification, and should not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0050] In order to make the purpose, technical solutions and advantages of the present application more apparent, the following is a detailed description of example embodiments of the present application with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application described in this application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of this application.

[0051] In view of the existence of the above technical problems, the present invention proposes a method for screening flash memory with a wide temperature range. Figure 1 A schematic flow chart of a method for screening a flash memory with a wide temperature range according to an embodiment of the present invention is shown.

[0052] In step S100, original particles are provided, and wide temperature screening is performed on the original particles to obtain read error bits of the original particles. According to the read error bits, the original particles are divided into test samples with multiple read error bit thresholds.

[0053] In step S200 , an initial yield of a test sample is obtained based on a plurality of test samples with read error bit thresholds.

[0054] In step S300, the test sample is subjected to full disk wear processing, and the number of full disk wears is counted in real time; when the number of full disk wears reaches a first specified number of wears, the test sample is subjected to a first wide temperature verification to obtain a first yield of the test sample.

[0055] In step S400 , when the number of times the entire disk is worn reaches a second specified number of times, a second wide temperature verification is performed on the test sample to obtain a second yield of the test sample.

[0056] In step S500 , when the number of times the entire disk is worn reaches a third specified number of times, a third wide temperature verification is performed on the test sample to obtain a third yield of the test sample.

[0057] In step S600 , a designated read error bit threshold is selected as an indicator for wide temperature screening based on the initial yield, the first yield, the second yield, and the third yield, and subsequent original particles are screened at a wide temperature based on the indicator.

[0058] The wide-temperature screening method for flash memory of the present invention performs wide-temperature screening on original particles, divides the original particles into multiple test samples with read error bit thresholds according to the different read error bits of the original particles, obtains the initial yield of the test samples based on the multiple read error bit threshold test samples, performs full-disk wear on the test samples, performs wide-temperature verification on the test samples at different wear stages and obtains the yield, selects a specified read error bit threshold as an indicator for wide-temperature screening based on the yield and initial yield of the test samples with multiple read error bit thresholds at different wear stages, and performs wide-temperature screening on subsequent original particles based on the indicator. The specified read error bit threshold determined by this method is used as the screening indicator for subsequent wide-temperature screening within the factory, and the particles screened out based on this screening indicator have the highest yield over the entire life cycle.

[0059] With the popularity of embedded systems and mobile devices, the requirements for storage technology are constantly increasing. NAND flash memory, as a non-volatile storage technology widely used in modern storage systems, has been widely used in various electronic devices due to its high density and low cost.

[0060] In an embodiment of the present application, original particles are provided in step S100, and wide temperature screening is performed on the original particles to obtain read error bits of the original particles. Based on the read error bits, the original particles are divided into test samples with multiple read error bit thresholds. Original particles refer to memory chips (such as NAND Flash, DRAM, etc.) produced by the chip manufacturer without any secondary processing by a third party. Random sampling of original particles is performed for wide temperature testing, and full-capacity read and write operations are performed on the particles at each temperature node (such as -40°C, 25°C, and 85°C). The error bits (Bit Error) of each read and write are recorded by the tester. Common indicators include: Raw Error Rate (Raw BER): The proportion of error bits that have not been processed by error correction coding (such as ECC) to the total data bits. Uncorrectable Error (UECC): Error bits that cannot be corrected after ECC correction.

[0061] In an embodiment of the present application, the original particles are divided into a plurality of test samples of read error bit thresholds according to the read error bits, including: screening out original particles with different read error bit thresholds through wide temperature screening, screening out the same number of test samples from original particles with each read error bit threshold, and obtaining test samples of multiple read error bit thresholds. A wide temperature test is performed at the early stage of particle life (BOL) to identify potential reliability defects and ensure the stability of storage products in extreme temperature environments. The read error bit (Read Error Bit) reflects the bit error rate of the particle when reading and writing data, and the threshold setting is directly related to the reliability level of the particle. The original particles are randomly sampled for BOL wide temperature screening to screen out particles with different read error bit thresholds, and N samples are screened out for each threshold.

[0062] Taking the read error bit thresholds of 70, 80, 100, 120, 150, 180, 200, and 220 as examples, N test samples are screened out for each read error bit threshold, with N = 20 as an example. In order to screen out the test samples corresponding to different read error bits, samples need to be randomly selected from the original particles for wide temperature screening. The number of original particle samples required for different read error bit thresholds is also different, denoted as M 70 、M 80 、M 100 、M 120 、M 150 、M 180 、M 200 、M 200 .

[0063] In the embodiment of the present application, the wide temperature screening includes stage one, stage two and stage three, and the original particles are subjected to wide temperature screening. Figure 2 A schematic flow chart of wide temperature screening of original particles is shown. In step S110, the original particles are divided into original bad blocks and original good blocks, and the original bad blocks are recorded in the original bad block table. In step S120, in stage one, a first test is performed on the original good blocks to obtain stage one bad blocks and stage one good blocks, and the stage one bad blocks are recorded in bad block table one. In step S130, in stage two, a second test is performed on the stage one good blocks to obtain stage two bad blocks and stage two good blocks, and the stage two bad blocks are recorded in bad block table two. In step S140, in stage three, a third test is performed on the stage two good blocks to obtain stage three bad blocks and stage three good blocks, and the stage three bad blocks are recorded in bad block table three. In step S150, when the number of bad blocks in the original bad block table, bad block table one, bad block table two and bad block table three is less than the specified number, the original particles pass the wide temperature screening; otherwise, the original particles do not pass the wide temperature screening.

[0064] The screening logic for wide temperature screening of BOL of original particles is as follows:

[0065] In step S110, the original chips are classified into original bad blocks and original good blocks, and the original bad blocks are recorded in the original bad block table. First, an initial bad block scan (identifying original bad blocks) is performed, and all storage blocks of the original chips are subjected to an initial full-capacity read and write test. The addresses of storage blocks that fail the test are recorded. Such storage blocks are marked as original bad blocks and entered into the original bad block table (OBBT). The table contains the storage block address, bad block type (such as Program / Erase error), and detection time. The table records any inherent bad blocks that existed on the storage medium before leaving the factory. These bad blocks are typically caused by manufacturing defects, material flaws, and other reasons. Storage blocks not entered into the original bad block table are original good blocks.

[0066] In step S120, in phase one, a first test is performed on the original good blocks to obtain phase one bad blocks and phase one good blocks, and the phase one bad blocks are recorded in bad block table one. In phase one, a first test is performed on the storage blocks not marked in the original bad block table (i.e., the original good blocks). The first test is a high-write and high-read test (e.g., continuously writing data and immediately reading and verifying). After completing a certain number of cycles (e.g., 10 times), the test is paused and all storage blocks are scanned. If a new read or write error storage block is found, it is determined to be a phase one bad block and recorded in bad block table one (SBBT1). The content includes: storage block address, error type, number of cycles when the first error occurred, and detection time. Testing continues until the preset number of cycles is reached or the number of bad blocks stabilizes. Storage blocks not entered in the original bad block table or bad block table one are phase one good blocks.

[0067] In step S130, in stage 2, a second test is performed on the good blocks in stage 1 to obtain bad blocks and good blocks in stage 2. The bad blocks in stage 2 are recorded in bad block table 2. In stage 2, the addresses of storage blocks already in the original bad block table and bad block table 1 (i.e., good blocks in stage 1) are excluded. A second test is performed on the good blocks in stage 1. The second test consists of a high-write-low-read and a low-write-low-read test. The high-write-low-read test performs a high-frequency write (e.g., full-load write) on the target storage block, followed by a low-frequency read to verify data integrity. If the read data is inconsistent with the written data, the storage block is marked as a bad block in stage 2. The low-write-low-read test performs a low-frequency write and read on the target storage block to verify long-term storage stability. If the read data is erroneous or lost, the storage block is marked as a bad block in stage 2. Bad blocks in stage 2 are recorded in bad block table 2 (SBBT2). Storage blocks not entered in the original bad block table, bad block table 1, or bad block table 2 are good blocks in stage 2.

[0068] In step S140, in stage three, a third test is performed on the good blocks in stage two, resulting in bad blocks and good blocks in stage three. The bad blocks in stage three are recorded in bad block table three. In stage three, the addresses of storage blocks already in the original bad block table, bad block table one, and bad block table two (i.e., good blocks in stage two) are excluded. A third test is performed on the good blocks in stage two. This test is a low-write, high-read test. After a low-frequency write, the target storage block is read at a high frequency. If the read data is erroneous or lost, the storage block is marked as a bad block in stage three. The bad blocks in stage three are recorded in bad block table three (SBBT3).

[0069] In step S150, if the number of bad blocks in the original bad block table, bad block table 1, bad block table 2, and bad block table 3 is less than a specified number, the original chip passes the wide temperature screening; otherwise, the original chip fails the wide temperature screening. A determination is made as to whether the sum of the number of bad blocks in the original bad block table, bad block table 1, bad block table 2, and bad block table 3 is less than a set bad block threshold. If the number of bad blocks in the original bad block table, bad block table 1, bad block table 2, and bad block table 3 is less than a specified number, the original chip passes the wide temperature screening; otherwise, the original chip fails the wide temperature screening.

[0070] In one embodiment, when the actual read error bit of a memory block is greater than the specified read error bit, the memory block is a bad block.

[0071] In an embodiment of the present application, the initial yield of the test sample is obtained based on the test sample with multiple read error bit thresholds in step S200 .

[0072] In an embodiment of the present application, the initial yield of the test samples is obtained based on the test samples of multiple read error bit thresholds, including: obtaining the initial yield of the test samples based on the number of original particles required for each read error bit threshold and the number of test samples for each read error bit threshold that pass the wide temperature screening. For example, in order to screen N test samples with a read error bit threshold of 70, it is necessary to randomly select samples from the original particles for wide temperature screening. The number of original particle samples required for N read error bit thresholds of 70 is M. 70 The initial yield estimate for a test sample with a read error bit threshold of 70 is calculated as N / M 70 Similarly, the initial yields of the test samples with different read error bit thresholds are N / M 70 、N / M 80 、N / M 100 、N / M 120 、N / M 150 、N / M 180 、N / M 200 、N / M 220 .

[0073] BOL yield YBOL The estimated calculation formula and the yield calculated based on the formula are shown in Table 1. According to the yield estimation formula, the yield under different read error bit thresholds is calculated. BOL The estimated yield change curve of BOL is drawn based on the size of BOL. The estimated yield change curve of BOL is shown in the figure below. Figure 3 As shown:

[0074] Table 1

[0075] ;

[0076] From Table 1 and Figure 3 It can be seen that the estimated yield of BOL gradually approaches 100% when the read error bit threshold is 150, and the estimated yield is 100% when the read error bit threshold is 180.

[0077] To verify which read error bit threshold during the BOL phase meets the wide temperature requirements throughout the entire lifecycle, end-of-life (EOL) verification is required for the test samples screened during the BOL phase. The screening logic for the EOL wide temperature verification of the test samples is consistent with the BOL wide temperature screening of the original device. The EOL wide temperature verification of the test samples includes the first wide temperature verification, the second wide temperature verification, and the third wide temperature verification. The screening logic for the first, second, and third wide temperature verifications is consistent with the BOL wide temperature screening of the original device.

[0078] In an embodiment of the present application, in step S300, the test sample is subjected to full disk wear processing, and the number of full disk wears is counted in real time; when the number of full disk wears reaches a first specified number of wears, the test sample is subjected to a first wide temperature verification to obtain a first yield of the test sample.

[0079] In an embodiment of the present application, the first wide temperature verification includes a desired number of wide temperature verifications. When the number of full disk wears reaches a first specified number of wears, the first wide temperature verification is performed on the test sample to obtain a first yield of the test sample. The first wide temperature verification includes: performing the desired number of wide temperature verifications on the test sample. If the desired number of wide temperature verifications are passed, the test sample passes the first wide temperature verification; otherwise, the test sample fails the first wide temperature verification. The first yield of the test sample at each read error bit threshold is calculated by comparing the number of test samples at each read error bit threshold before full disk wear with the number of test samples at each read error bit threshold that pass the first wide temperature verification. The desired number of wide temperature verifications may include three wide temperature verifications, and the first wide temperature verification includes three wide temperature verifications.

[0080] The particles screened out in the wide temperature screening are subjected to full disk erase and write wear, and the erase-program cycle (EPC) of the full disk wear is counted in real time. The first specified wear number can be 1K, and it is worn to EPC=1K. 1K EPC = 1,000 complete Program / Erase cycles. It pauses every time the specified EPC number is reached, and EOL wide temperature verification is performed at the pause point (usually covering extreme temperature environments such as -40°C to 85°C). 1K EPC can reflect the early life performance. The screening logic of the wide temperature verification when EPC = 1K is consistent with the screening logic of the BOL wide temperature screening of original particles. The first EOL wide temperature verification is performed at EPC = 1K, and the test is performed three times. The three test results are recorded, and the number of test samples P that passed the three tests for each threshold is counted. The number of test samples that passed the three wide temperature tests for each threshold of EPC = 1K is counted, which are P respectively. 70 、P 80 、P 100 、P 120 、P 150 、P 180 、P 200 、P 220 The first yield estimation formula of the test sample with a read error bit threshold of 70 is P 70 / N. Similarly, the first yields of the test samples with different read error bit thresholds are P 70 / N, P 80 / N、P 100 / N、P 120 / N、P 150 / N, P 180 / N、P 200 / N、P 220 / N.

[0081] Estimated wide temperature test yield Y at EPC = 1K EOL_1K The estimated calculation formula and the yield calculated based on the formula are shown in Table 2:

[0082] Table 2

[0083] ;

[0084] As can be seen from Table 2, the estimated yield when EPC = 1K is 100% at different read error bit thresholds.

[0085] In an embodiment of the present application, the screening method also includes the following steps: the test samples that fail the first wide temperature verification are not subjected to the second wide temperature verification; the test samples that pass the first wide temperature verification are subjected to full disk wear, and when the number of full disk wear reaches a second specified number of wear times, the test samples that pass the first wide temperature verification are subjected to the second wide temperature verification.

[0086] In an embodiment of the present application, when the number of times the entire disk is worn reaches a second specified number of times in step S400 , a second wide temperature verification is performed on the test sample to obtain a second yield of the test sample.

[0087] In an embodiment of the present application, the second wide temperature verification includes a desired number of wide temperature verifications. When the number of full disk wears reaches a second specified number of wears, the second wide temperature verification is performed on the test sample to obtain a second yield of the test sample. The second wide temperature verification includes: performing the desired number of wide temperature verifications on the test sample. If the desired number of wide temperature verifications are passed, the test sample passes the second wide temperature verification; otherwise, the test sample fails the second wide temperature verification. The second yield of the test sample at each read error bit threshold is calculated by comparing the number of test samples at each read error bit threshold before full disk wear with the number of test samples at each read error bit threshold that pass the second wide temperature verification. The desired number of wide temperature verifications may include three wide temperature verifications, and the second wide temperature verification includes three wide temperature verifications.

[0088] Continue to perform full disk erase and wear on the screened particles until EPC = 2K. The second specified wear number can be 2K. 2K EPC = 2,000 complete Program / Erase cycles, pause every time the specified EPC number is reached, and perform EOL wide temperature verification at the pause point. 2K EPC can reflect the mid-term life performance. The screening logic of the wide temperature verification when EPC = 2K is consistent with the screening logic of the BOL wide temperature screening of the original particles. Perform the second EOL wide temperature verification at EPC = 2K, test three times, record the three test results, and count the number of test samples Q that passed the three tests for each threshold; count the number of test samples that passed the three wide temperature tests for each threshold of EPC = 2K, which are Q respectively. 70 , Q 80 , Q 100 , Q 120 , Q 150 , Q 180 , Q 200 , Q 220 The second yield estimation formula for the test sample with a read error bit threshold of 70 is Q 70 / N. Similarly, the second yields of the test samples with different read error bit thresholds are Q 70 / N, Q 80 / N, Q 100 / N, Q 120 / N, Q 150 / N、Q 180 / N, Q 200 / N, Q 220 / N.

[0089] Estimated wide temperature test yield Y at EPC = 2K EOL_2K The estimated calculation formula and the yield calculated based on the formula are shown in Table 3:

[0090] Table 3

[0091] ;

[0092] It can be seen from Table 3 that the estimated yield when EPC = 2K gradually increases with the increase of the read error bit threshold.

[0093] In an embodiment of the present application, the screening method also includes the following steps: the test samples that fail the second wide temperature verification are not subjected to the third wide temperature verification; the test samples that pass the second wide temperature verification are subjected to full disk wear, and when the number of full disk wear reaches the third specified number of wears, the test samples that pass the second wide temperature verification are subjected to the third wide temperature verification.

[0094] In an embodiment of the present application, when the number of times the entire disk is worn reaches a third specified number of times in step S500 , a third wide temperature verification is performed on the test sample to obtain a third yield of the test sample.

[0095] In an embodiment of the present application, the third wide temperature verification includes a desired number of wide temperature verifications. When the number of full disk wears reaches a third specified number of wears, the third wide temperature verification is performed on the test sample to obtain a third yield of the test sample. The third wide temperature verification includes: performing the desired number of wide temperature verifications on the test sample. If the desired number of wide temperature verifications are passed, the test sample passes the third wide temperature verification; otherwise, the test sample fails the third wide temperature verification. The third yield of the test sample for each read error bit threshold is calculated by comparing the number of test samples for each read error bit threshold before full disk wear with the number of test samples for each read error bit threshold that pass the third wide temperature verification. The desired number of wide temperature verifications may include three wide temperature verifications, and the third wide temperature verification may include three wide temperature verifications.

[0096] Continue to perform full disk erase and wear on the screened particles until EPC = 3K. The third specified wear number can be 3K. 3K EPC = 3,000 complete Program / Erase cycles, pause every time the specified EPC number is reached, and perform EOL wide temperature verification at the pause point. 3K EPC can reflect the performance close to the end of the design life. The screening logic of the wide temperature verification when EPC = 3K is consistent with the screening logic of the BOL wide temperature screening of the original particles. Perform the third EOL wide temperature verification at EPC = 3K, test three times, record the three test results, and count the number of test samples X that passed the three tests for each threshold; count the number of test samples that passed the three wide temperature tests for each threshold at EPC = 3K, which are X respectively. 70 、X 80 、X 100 、X 120 、X 150 、X 180 、X 200 、X 220 The third yield estimation formula of the test sample with a read error bit threshold of 70 is X 70 / N. Similarly, the third yield of the test samples with different read error bit thresholds is X 70 / N、X 80 / N, X 100 / N、X 120 / N, X 150 / N, X 180 / N, X 200 / N, X 220 / N.

[0097] Estimated wide temperature test yield Y when EPC = 3K EOL_3K The estimated calculation formula and the yield calculated based on the formula are shown in Table 4:

[0098] Table 4

[0099] ;

[0100] As can be seen from Table 4, the estimated yield when EPC = 3K reaches its highest when the read error bit threshold is 150. As the read error bit threshold continues to increase, the yield gradually decreases.

[0101] In an embodiment of the present application, in step S600, a specified read error bit threshold is selected as an indicator for wide temperature screening based on the initial yield, the first yield, the second yield, and the third yield, and subsequent original particles are screened at a wide temperature based on the specified read error bit threshold.

[0102] According to the yield estimation formula, the yield under different read error bit thresholds is calculated, and the Y under different thresholds is calculated. EOL_3K The size of the EOL yield curve is drawn, such as Figure 4 As shown in the figure, combining the BOL and EOL estimated yields, we ultimately selected a read error bit threshold of 150 as the metric for screening products that meet the wide-temperature standard throughout their lifecycle. Using this method to determine the read error bit metric as a screening criterion for subsequent wide-temperature screening within the factory, the screened particles achieved the highest yield throughout their entire lifecycle.

[0103] The present invention provides a method for screening flash memory for wide temperature, by performing wide temperature screening on original particles, dividing the original particles into test samples with multiple read error bit thresholds according to the different read error bits of the original particles, obtaining the initial yield of the test samples based on the multiple read error bit threshold test samples, performing full disk wear on the test samples, performing wide temperature verification on the test samples at different wear stages and obtaining the yield, selecting a specified read error bit threshold as an indicator for wide temperature screening based on the yield and initial yield of the test samples with multiple read error bit thresholds at different wear stages, and performing wide temperature screening on subsequent original particles based on the specified read error bit threshold. This method determines the specified read error bit threshold as the screening standard for wide temperature screening within the subsequent factory, and the screened particles have the highest yield over the entire life cycle.

[0104] See also Figure 5 As shown, this embodiment also provides a computer-readable storage medium 5, which stores computer instructions 50 for using the bad block management method. The computer-readable storage medium 5 can be an electronic medium, a magnetic medium, an optical medium, an electromagnetic medium, an infrared medium, or a semiconductor system or a propagation medium. The computer-readable storage medium 5 can also include semiconductor or solid-state memory, magnetic tape, a removable computer disk, random access memory (RAM), read-only memory (ROM), a hard disk, and an optical disk. Optical disks can include compact disk-read only memory (CDROM), compact disk-read / write (CD-RW), and DVD.

[0105] The embodiments of the present invention disclosed above are intended only to illustrate the present invention. They do not describe all details in detail, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for screening flash memory with a wide temperature range, characterized in that: The method comprises: Providing original particles, performing wide temperature screening on the original particles to obtain read error bits of the original particles, and dividing the original particles into test samples with multiple read error bit thresholds based on the read error bits; Obtaining an initial yield of the test sample according to a plurality of test samples having read error bit thresholds; Performing a full-disc wear treatment on the test sample, and counting the number of full-disc wears in real time; When the number of times the entire disk is worn reaches a first specified number of times, performing a first wide temperature verification on the test sample to obtain a first yield of the test sample; When the number of times the entire disk is worn reaches a second specified number of times, performing a second wide temperature verification on the test sample to obtain a second yield of the test sample; When the number of times the entire disk is worn reaches a third specified number of times, performing a third wide temperature verification on the test sample to obtain a third yield of the test sample; According to the initial yield, the first yield, the second yield, and the third yield, a designated read error bit threshold is selected as an indicator for wide temperature screening, and subsequent original particles are screened at a wide temperature according to the indicator.

2. The screening method according to claim 1, wherein The method of dividing the original chips into a plurality of test samples with read error bit thresholds according to the read error bits includes: Through wide temperature screening, original particles with different read error bit thresholds are screened out, and the same number of test samples are screened out from original particles with each read error bit threshold to obtain test samples with multiple read error bit thresholds.

3. The screening method according to claim 2, wherein The step of obtaining an initial yield of the test sample based on the test sample having multiple read error bit thresholds includes: The initial yield of the test samples is obtained according to the number of original chips required for each read error bit threshold and the number of test samples for each read error bit threshold that pass the wide temperature screening.

4. The screening method according to claim 1, wherein The wide temperature screening includes stage one, stage two, and stage three. The wide temperature screening of the original particles includes: Divide the original particles into original bad blocks and original good blocks, and record the original bad blocks in an original bad block table; In the first stage, a first test is performed on the original good blocks to obtain the first stage bad blocks and the first stage good blocks, and the first stage bad blocks are recorded in the first bad block table; In the second stage, a second test is performed on the good blocks in the first stage to obtain bad blocks and good blocks in the second stage, and the bad blocks in the second stage are recorded in the second bad block table; In the third stage, a third test is performed on the good blocks in the second stage to obtain bad blocks and good blocks in the third stage, and the bad blocks in the third stage are recorded in the bad block table 3; When the number of bad blocks in the original bad block table, the bad block table 1, the bad block table 2, and the bad block table 3 is less than the specified number, the original particles pass the wide temperature screening; otherwise, the original particles fail the wide temperature screening.

5. The screening method according to claim 1, wherein The first wide temperature verification includes a desired number of wide temperature verifications. When the number of full disk wear reaches a first specified number of wears, the first wide temperature verification is performed on the test sample to obtain a first yield of the test sample, including: The test sample is subjected to a desired number of wide temperature verifications. If the desired number of wide temperature verifications are passed, the test sample passes the first wide temperature verification. Otherwise, the test sample fails the first wide temperature verification. The first yield of the test samples of each read error bit threshold is calculated by comparing the number of test samples of each read error bit threshold before full disk wear and the number of test samples of each read error bit threshold that pass the first wide temperature verification.

6. The screening method according to claim 5, wherein The screening method further comprises the following steps: Test samples that fail the first wide temperature verification will not undergo the second wide temperature verification; The test sample that passed the first wide temperature verification is subjected to full disk wear. When the number of full disk wear reaches a second specified wear number, the test sample that passed the first wide temperature verification is subjected to a second wide temperature verification.

7. The screening method according to claim 1, wherein The second wide temperature verification includes a desired number of wide temperature verifications, and when the number of full disk wear reaches a second specified number of wears, performing the second wide temperature verification on the test sample to obtain a second yield of the test sample includes: The test sample is subjected to a desired number of wide temperature verifications. If the desired number of wide temperature verifications are passed, the test sample passes the second wide temperature verification. Otherwise, the test sample fails the second wide temperature verification. The second yield of the test samples for each read error bit threshold is calculated by comparing the number of test samples for each read error bit threshold before full disk wear and the number of test samples for each read error bit threshold that pass the second wide temperature verification.

8. The screening method according to claim 7, wherein The screening method further comprises the following steps: Test samples that fail the second wide temperature verification will not undergo the third wide temperature verification; The test sample that passed the second wide temperature verification is subjected to full disk wear. When the number of full disk wear reaches a third specified wear number, the test sample that passed the second wide temperature verification is subjected to a third wide temperature verification.

9. The screening method according to claim 1, wherein The third wide temperature verification includes a desired number of wide temperature verifications. When the number of full disk wear times reaches a third specified number of wear times, the third wide temperature verification is performed on the test sample to obtain a third yield of the test sample, including: The test sample is subjected to a desired number of wide temperature verifications. If the desired number of wide temperature verifications are passed, the test sample passes the third wide temperature verification. Otherwise, the test sample fails the third wide temperature verification. A third yield of the test samples at each read error bit threshold is calculated based on the number of test samples at each read error bit threshold before full disk wear and the number of test samples at each read error bit threshold that pass the third wide temperature verification.

10. A storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the processor implements the method for screening a flash memory with a wide temperature range according to any one of claims 1 to 9.

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