CN111951853B - Method and device for controlling erasing operation and Nand flash memory - Google Patents

Abstract

The invention provides a method and a device for controlling an erasing operation and a Nand flash memory. The method comprises the following steps: receiving an erase operation command, determining a word line to which an address of a memory cell needing to execute the erase operation belongs as a target word line, judging whether the target word line belongs to an edge word line, detecting whether a threshold voltage of the target word line is smaller than a preset voltage through a voltage detection unit if the target word line belongs to the edge word line, adjusting the erase operation voltage for the target word line through an edge word line charge pump according to the preset voltage if the threshold voltage of the target word line is larger than or equal to the preset voltage, and executing the erase operation corresponding to the erase operation command for the target word line. When the erasing operation is executed, the voltage difference between the grid electrode of the edge word line and the substrate is increased, so that the edge word line can complete erasing more quickly, the number of erasing cycles required by the erasing operation of the edge word line is reduced, the influence on the middle word line is reduced, the service life of the memory cell array is prolonged, and the operation reliability of the Nand flash memory is improved.

Description

A method, device and Nand flash memory for controlling erasing operation

technical field

The invention relates to the field of storage, in particular to a method and device for controlling an erasing operation and a Nand flash memory.

Background technique

At present, Nand flash memory includes: memory cell array, voltage detection unit and charge pump. The memory cell array is composed of multiple word lines. There are edge word lines and middle word lines in these word lines. The two word lines on the edge of the cell array, the word lines except these two edge word lines are the middle word lines; the charge pump provides the operating voltage for the memory cell array, the charge pump is divided into multiple stages, and one stage of the charge pump can be To provide operating voltage for multiple word lines, there are also extreme cases where one stage of the charge pump only provides operating voltage for one word line, which is determined according to the specific conditions of the Nand flash memory.

Due to the characteristics and arrangement of the Nand flash memory cell array itself, when an operation is performed on a word line, it will have a certain impact on the word line next to the word line. If the word line at address 0 is an edge word line, and operations such as reading, writing, and erasing are performed on the word line at address 0, the threshold voltage of the memory cell on the word line at address 0 will be affected accordingly, while the word line at address 1 When performing operations such as reading, writing, and erasing, both address 0 and address 2 will be affected. It can be seen from the above that the edge word line is only affected by one adjacent word line, but the middle word line is indeed affected by two adjacent word lines at the same time.

Due to the characteristics of the memory cell itself, as the usage time of the Nand flash memory increases, the number of operations performed will also increase, making the edge word line more disturbed than the middle word line, resulting in the same operating voltage It is easy to make mistakes when performing various operations on the memory cell array, which affects the operational reliability of the Nand flash memory.

Contents of the invention

The present invention provides a method and device for controlling erasing operations and a Nand flash memory, which solves the problem that when the Nandflash memory performs some types of operations, the operating reliability of the Nand flash memory is relatively low due to the use of the same voltage to perform operations on the memory cell array. low problem.

In order to solve the above-mentioned technical problems, an embodiment of the present invention provides a method for controlling an erasing operation, the method is applied to a Nand flash memory, and the Nand flash memory includes: a memory cell array, a voltage detection unit, and a charge pump. The memory cell array includes: edge word lines and middle word lines, the edge word lines are two word lines at the edge positions of the memory cell array, and the middle word lines are the two word lines at the edge positions in the memory cell array. A plurality of word lines other than two word lines, the charge pump includes: an edge word line charge pump, the edge word line charge pump provides an operating voltage for the edge word line, and each word line includes a plurality of memory cells; The methods include:

Receive an erase operation instruction, the erase operation instruction includes: the address of the storage unit that needs to perform the erase operation;

Determining that the word line to which the address of the memory cell to be erased belongs belongs to the target word line, and judging whether the target word line belongs to the edge word line;

If the target word line belongs to the edge word line, detecting whether the threshold voltage of the edge word line where the target word line is located is less than a preset voltage by the voltage detection unit;

If the threshold voltage is greater than or equal to the preset voltage, adjusting an erase operation voltage for the target word line through the edge word line charge pump according to the preset voltage;

According to the adjusted erasing operation voltage, the erasing operation corresponding to the erasing operation instruction is performed on the edge word line where the target word line is located.

Optionally, the adjusted voltage value of the erasing operation voltage satisfies a preset condition, and the preset condition is: for the same erasing operation,

The number of erasing cycles required by the edge word line where the target word line is located to perform the erase operation is less than or equal to the number of erase cycles required by the intermediate word line to perform the erase operation.

Optionally, the charge pump further includes: an intermediate word line charge pump, the intermediate word line charge pump provides an operating voltage for the intermediate word line, and if the target word line belongs to the edge word line, then through the After the voltage detection unit detects whether the threshold voltage of the edge word line where the target word line is located is less than a preset voltage, the method further includes:

If the threshold voltage is less than the preset voltage, the edge word line charge pump provides an erase operation voltage for the edge word line, and the erase operation voltage is equal to the intermediate word line charge pump. The erasing operation voltages provided by the word lines are equal in magnitude.

Optionally, if the target word line belongs to the edge word line, using the voltage detection unit to detect whether the threshold voltage of the edge word line where the target word line is located is less than a preset voltage includes: When the word line belongs to the edge word line and the number of erasing cycles required to complete the erasing operation on the target word line is greater than a preset number of times, the voltage detection unit detects where the target word line is located. Whether the threshold voltage of the edge word line is lower than a preset voltage.

Optionally, it is characterized in that, according to the preset voltage, adjusting the erasing operation voltage for the target word line through the edge word line charge pump includes:

determining the adjustment range based on the preset voltage;

According to the adjustment range, the erase operation voltage for the target word line is adjusted through the edge word line charge pump.

The embodiment of the present invention also provides a device for controlling an erasing operation, the device is applied to a Nand flash memory, and the Nand flash memory includes: a memory cell array, a voltage detection unit and a charge pump, and the memory cell array includes: An edge word line and an intermediate word line, the edge word lines are two word lines at the edge positions of the memory cell array, and the intermediate word lines are other than the two word lines at the edge positions in the memory cell array A plurality of word lines, the charge pump includes: an edge word line charge pump, the edge word line charge pump provides an operating voltage for the edge word line, each word line includes a plurality of memory cells; the device includes:

The receiving instruction module is used to receive the erasing operation instruction, and the erasing operation instruction includes: the address of the storage unit required to perform the erasing operation;

A determining and judging module, configured to determine that the word line to which the address of the memory cell to be erased belongs belongs to the target word line, and determine whether the target word line belongs to the edge word line;

A detection voltage module, configured to detect whether the threshold voltage of the edge word line where the target word line is located is less than a preset voltage through the voltage detection unit if the target word line belongs to the edge word line;

A voltage adjustment module, configured to adjust the erase operation voltage for the target word line through the edge word line charge pump according to the preset voltage if the threshold voltage is greater than or equal to the preset voltage;

The executing operation module is configured to execute the erasing operation corresponding to the erasing operation instruction on the edge word line where the target word line is located according to the adjusted erasing operation voltage.

Optionally, the charge pump further includes: an intermediate word line charge pump, the intermediate word line charge pump provides an operating voltage for the intermediate word line, and the device further includes:

providing a voltage module, configured to provide an erase operation voltage for the edge word line through the edge word line charge pump if the threshold voltage is less than the preset voltage, and the erase operation voltage is the same as that of the middle word line The erase operation voltages provided by the charge pumps to the middle word lines are equal in magnitude.

Optionally, the device also includes:

A detection threshold module, configured to pass the voltage when the target word line belongs to the edge word line and the number of erasing cycles required to complete the erasing operation on the target word line is greater than a preset number of times The detection unit detects whether the threshold voltage of the edge word line where the target word line is located is lower than a preset voltage.

Optionally, the voltage adjustment module includes:

A determining submodule, configured to determine the adjustment range based on the preset voltage;

The adjustment sub-module is used to adjust the erase operation voltage for the target word line through the edge word line charge pump according to the adjustment range.

The embodiment of the present invention also provides a Nand flash memory, the Nand flash memory includes: a memory cell array, a voltage detection unit and a charge pump, the memory cell array includes: an edge word line and a middle word line, and the edge word The lines are two word lines at the edge positions of the memory cell array, the middle word lines are multiple word lines in the memory cell array except the two word lines at the edge positions, and the charge pump includes: Edge word line charge pumps and middle word line charge pumps, the edge word line charge pumps provide operating voltages for the edge word lines, the middle word line charge pumps provide operating voltages for the middle word lines, each word line Including a plurality of storage units; the Nand flash memory is used to perform any of the methods described above.

Compared with the prior art, a method, device and Nand flash memory for controlling an erasing operation provided by the present invention receive an erasing operation instruction, and determine that the word line to which the address of the memory cell that needs to perform the erasing operation belongs is the target Word line, and judge whether the target word line belongs to the edge word line, if the target word line belongs to the edge word line, then detect whether the threshold voltage of the edge word line where the target word line is located is less than the preset voltage through the voltage detection unit, if the threshold voltage is greater than equal to the preset voltage, then according to the preset voltage, the erase operation voltage for the target word line is adjusted through the edge word line charge pump, and the erase operation is performed on the edge word line where the target word line is located according to the adjusted erase operation voltage The erase operation corresponding to the operation instruction. The scheme of the present invention judges whether the word line to which the memory cell to perform the erasing operation belongs is an edge word line, and if it is an edge word line, then adjusts the power supply voltage of the charge pump that provides the operating voltage for the edge word line to enlarge the edge word line. The voltage difference between the gate voltage and the substrate enables the edge word lines to be erased faster and successfully, reducing the number of erase cycles required for the edge word lines to perform an erase operation, thereby reducing the impact on the middle word lines, While prolonging the service life of the entire memory cell array, the reliability of Nand flash memory operation is improved.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments of the present invention. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention , for those skilled in the art, other drawings can also be obtained according to these drawings without paying creative labor.

FIG. 1 is a flowchart of a method for controlling an erasing operation according to an embodiment of the present invention;

Fig. 2 is the schematic diagram inside the Nand flash memory of the embodiment of the present invention;

FIG. 3 is a block diagram of an apparatus for controlling an erasing operation according to an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The inventor finds that existing Nand flash memory storage unit can produce a problem when erasing operation: after Nand flash memory has been used for a period of time, when using the erasing operating voltage of the same voltage value again, the same number of erasing cycles is basically The edge word line and the middle word line cannot be erased successfully at the same time. Generally, the edge word line needs more erasing cycles before it can be successfully erased, but because the Nand flash memory performs the erase operation in units of blocks Therefore, when the edge word line needs more erase cycles to complete the erase operation, the middle word line will also be erased, causing the middle word line to be erased too deeply, which seriously affects the middle word line. The service life of the line leads to low erasing reliability of the Nandflash memory.

The inventor further found that the reason for the above problems is: because of the characteristics of the memory cell and the particularity of the edge word line, the edge word line is more disturbed than the middle word line in the program operation or read operation, and the threshold voltage will rise more. higher. For example: there are 10 word lines in the storage cell array in the Nand flash memory, and the addresses are wl0, wl1, wl2, wl3, wl4, wl5, wl6, wl7, wl8, wl9, where wl0 and wl9 are edge word lines, and the rest of the word lines are line is the middle word line, assuming that the program operation or read operation has been performed on these 10 word lines, then the two edge word lines wl0 and wl9 are relatively For the 8 middle word lines, they are more disturbed, and their threshold voltages will be higher than those of the middle word lines.

A problem arises from the above. After the program operation or read operation is completed, when it is necessary to perform an erase operation on these 10 word lines, because the threshold voltage of the edge word lines is higher than that of the middle word lines, the 10 word lines Using the same erase operation voltage to perform the erase operation, the middle word line will be erased faster, while the edge word line needs more erase cycles to be erased successfully, but the erase operation is based on It is performed in units of blocks, so while continuing to perform the erase operation on the edge word lines, it may cause the middle word lines that have been successfully erased to be erased too deeply, thereby shortening the service life of the middle word lines, resulting in The reliability of Nand flash memory erase operation is low.

Based on the above problems, the inventor has conducted in-depth research, combined with the characteristics of the operating voltage provided by the charge pump in the Nand flash memory, and after a large number of field tests and simulation calculations, boldly and creatively proposed to use the charge pump to adjust the supply according to the operation content. The erase operation voltage of the edge word lines is different from that of the middle word lines, which solves the above-mentioned problems. The solution proposed by the inventor is explained and illustrated in detail below.

FIG. 1 shows a flowchart of a method for controlling an erasing operation according to an embodiment of the present invention. This method is applied to Nand flash memory, and Nand flash memory comprises: memory cell array, voltage detection unit and charge pump, and memory cell array comprises: edge word line and middle word line, and edge word line is two at memory cell array edge position The word line, the middle word line is a plurality of word lines in the memory cell array except the two word lines at the edge position, and the charge pump includes: the edge word line charge pump, the edge word line charge pump provides the operating voltage for the edge word line, Each word line includes a plurality of memory cells; the method for controlling the erasing operation includes the following steps:

Step 101: Receive an erase operation instruction, the erase operation instruction includes: the address of the storage unit to be executed the erase operation.

In the embodiment of the present invention, the Nand flash memory includes: a memory cell array, a voltage detection unit and a charge pump, and the memory cell array includes: an edge word line and an intermediate word line, and the edge word line is two word lines at the edge position of the memory cell array , the middle word line is a plurality of word lines except two word lines at the edge position in the memory cell array, the voltage detection unit is used to detect the threshold voltage on the memory cell, and the charge pump includes: edge word line charge pump, edge word line The line charge pump provides the operating voltage for the edge word line. When it is necessary to perform an erase operation, first the host computer sends an erase operation instruction to the Nand flash memory, and the Nand flash memory receives the erase operation instruction. The erase operation instruction includes the need to perform an erase operation. The address of the storage unit for the division operation. For example: as shown in Figure 2, the storage cell array in the Nand flash memory includes 10 word lines, and the addresses are wl0, wl1, wl2, wl3, wl4, wl5, wl6, wl7, wl8, wl9, where wl0 and wl9 are The edge word lines, wl1, wl2, wl3, wl4, wl5, wl6, wl7, wl8 are the middle word lines, the edge word line charge pump provides operating voltage for wl0 and wl9, and the middle word line charge pump is wl1, wl2, wl3, wl4 , wl5, wl6, wl7, wl8 provide operating voltage. Assuming that the data in the storage cells on five word lines needs to be erased, the address of the storage cells included in the erase operation command is the address corresponding to the storage cells on the five word lines.

Step 102: Determine the word line to which the address of the memory cell to be erased belongs to as the target word line, and determine whether the target word line belongs to the edge word line.

In the embodiment of the present invention, after the Nand flash memory receives the erase operation instruction, first determine the word line to which the address of the memory cell included in the erase operation instruction belongs, after determining the target word line, then judge whether the target word line belongs to the edge word Wire. For example, in Figure 2, it is assumed that the address of the storage unit included in the erase operation instruction is: 00000H～FFFFFH, and the word line to which it belongs includes wl0～wl4, that is, the target word line includes wl0～wl4, and then the word line wl0～wl4 Whether any word line is an edge word line is judged.

Step 103 : If the target word line belongs to the edge word line, the voltage detection unit detects whether the threshold voltage of the edge word line where the target word line is located is lower than a preset voltage.

In the embodiment of the present invention, after it is determined that the target word line belongs to the edge word line, the voltage detection unit detects whether the threshold voltage of the edge word line where the target word line is located is lower than a preset voltage. The purpose of setting the preset voltage is to use the preset voltage as the reference for the erase operation voltage provided by the edge word line charge pump when the edge word line needs a higher voltage difference to reduce the number of erase cycles to perform the erase operation. , the preset voltage is an empirical value obtained through a large number of tests and simulation calculations. For example: in Figure 2, the preset voltage is 6.5V, the target word lines include wl0~wl4, where wl0 is the edge word line, wl1~wl4 are the middle word lines, the threshold voltage of wl0 detected by the voltage detection unit is 6.5V, The threshold voltage of wl1 is 6.3V, the threshold voltage of wl2 is 6.2V, the threshold voltage of wl3 is 6.1V, and the threshold voltage of wl4 is 6.0V. Of course, in general, in order to make the Nandflash memory run faster, the threshold voltage detection will not be performed specifically for each word line. After the end, the threshold voltage of each word line basically fluctuates up and down within a range of empirical values. For example, the threshold voltage of the edge word line after the programming operation is generally empirically valued at 6.8V. After the actual programming operation, the threshold voltage of the edge word line The voltage is basically around 6.8V, with little deviation; the general experience value of the threshold voltage of the middle word line after the programming operation is 6.3V, then after the actual programming operation, the threshold voltage of the middle word line is basically around 6.3V, the deviation Therefore, it is not necessary to perform threshold voltage detection for each word line. If precise control is required, threshold voltage detection can also be performed for each word line, so as to achieve the purpose of precise control.

It should be noted that when the Nand flash memory is used or used for a period of time, the number of erase cycles required for the edge word line to perform the erase operation is the same or similar to the number of erase cycles required for the middle word line to perform the erase operation , it is not necessary to treat the edge word line and the middle word line differently at this time, just use the same erase operation voltage to ensure the number of erase cycles required for the edge word line to perform the erase operation and the middle word line to perform the erase operation The number of erase cycles required is the same or similar. When the same erase operation voltage is used, the number of erase cycles required for the edge word line to perform the erase operation is much greater than the number of erase cycles required for the middle word line to perform the erase operation, so it is not suitable to use the same erase operation voltage. The erase operation voltage is used to perform the erase operation on the edge word line and the middle word line. Generally, if the same erase operation voltage is used, the number of erase cycles required for the edge word line to perform the erase operation is greater than that of the middle word line. When the number of erasing cycles required to perform the erasing operation is more than 3 times, the erasing operation voltage needs to be provided separately for the edge word line, and at this time, it is necessary to detect whether the threshold voltage of the edge word line is lower than the preset voltage through the voltage detection unit .

Step 104: If the threshold voltage is greater than or equal to the preset voltage, adjust the erase operation voltage for the target word line through the edge word line charge pump according to the preset voltage.

In the embodiment of the present invention, if the detected threshold voltage of the edge word line where the target word line is located is greater than or equal to the preset voltage, the erase operation voltage for the target word line is adjusted by the edge word line charge pump according to the preset voltage. For example, as shown in FIG. 2 , the detected threshold voltage of wl0 is 6.5V, which is equal to the preset voltage of 6.5V. Then, according to the preset voltage of 6.5V, the erase operation voltage of wl0 is adjusted through the edge word line charge pump.

If the threshold voltage of the edge word line where the detection target word line is located is less than the preset voltage, when the erase operation is performed on the edge word line and the middle word line at the same time, the erase operation provided for the edge word line by the edge word line charge pump The voltage is equal to the erase operation voltage provided by the middle word line charge pump for the middle word line, that is, the erase operation is performed on the edge word line and the middle word line with the same erase operation voltage. For example: as shown in Figure 2, if the detected threshold voltage of wl0 is 6.3V, which is less than the preset voltage of 6.5V, then according to the preset voltage of 6.5V, the erase operation voltage provided for wl0 by the edge word line charge pump is the same as that in the middle The word line charge pumps provide equal erase operation voltages for the middle word lines.

Optionally, step 104 includes:

Step 104a: Determine the adjustment range based on the preset voltage.

Step 104b: According to the adjustment range, adjust the erase operation voltage for the target word line through the edge word line charge pump.

In the embodiment of the present invention, if the threshold voltage of the edge word line where the target word line is detected is greater than or equal to the preset voltage, then the preset voltage is used as a reference to determine the adjustment range, if the threshold voltage of the target word line is much greater than the preset voltage , the erase operation is performed on the target word line with a negative voltage far less than the absolute value of the preset voltage through the edge word line charge pump; if the threshold voltage of the target word line is slightly greater Perform an erase operation on the target word line with a negative voltage less than the absolute value of the preset voltage; if the threshold voltage of the target word line is equal to the preset voltage, use the negative voltage of the absolute value of the preset voltage to the target word line Perform a wipe operation.

For example: as shown in Figure 2, if the detected threshold voltage of wl0 is 8.5V, which is much higher than the preset voltage of 6.5V, then the edge word line charge pump will perform an erase operation on wl0 at -9.0V; if the detected wl0 The threshold voltage of wl0 is 7.0V, which is slightly higher than the preset voltage of 6.5V, and the erase operation is performed on wl0 at -7.0V through the edge word line charge pump; if the detected threshold voltage of wl0 is 6.5V, it is equal to the preset voltage of 6.5 V, then perform an erase operation on wl0 at -6.5V through the edge word line charge pump.

Step 105: According to the adjusted erasing operation voltage, perform an erasing operation corresponding to the erasing operation command on the edge word line where the target word line is located.

In the embodiment of the present invention, the edge word line charge pump adjusts the erase operation voltage for the target word line, and uses the voltage to execute the erase operation corresponding to the erase operation command on the edge word line where the target word line is located. The voltage value of the adjusted erase operation voltage satisfies the preset condition, the preset condition is: for the same erase operation, the number of erase cycles required for the edge word line where the target word line is located to perform the erase operation is less than or equal to that of the middle word The number of erase cycles required for the line to perform the erase operation.

For example: as shown in Figure 2, if the threshold voltage of wl0 after the programming operation is about 8.5V according to experience, the number of erase cycles required to perform the erase operation on wl0 at -9.0V through the edge word line charge pump is 3 times , the middle word line charge pump performs erase operation on wl1~wl4 at -6.0V, the number of erase cycles required is 3 times, and the edge word line erase operation will not affect the middle word line, the edge word line and the middle word line At the same time, the erase operation is completed; if the threshold voltage of wl0 after the programming operation is 7.0V according to experience, the number of erase cycles required to perform the erase operation on wl0 at -7.0V through the edge word line charge pump is 2 times, The charge pump of the middle word line needs to perform the erase operation on wl1~wl4 at -6.0V. The number of erase cycles is 3 times. The erase operation performed on the edge word line will not affect the middle word line, even if the middle word line performs the erase operation. One more erase cycle than the edge word line, so that the edge word line is erased once more, but the impact on the edge word line is not large, and the erase cycle required to perform the erase operation on wl0 at -7.0V The number of times may also need 3 times. At this time, the edge word line and the middle word line will not affect each other, and the edge word line and the middle word line will complete the erase operation at the same time; if the detected threshold voltage of wl0 is 6.5V according to experience , then the number of erasing cycles required to perform the erase operation on wl0 at -6.5V through the edge word line charge pump is 3 times, and the erasing cycle required to perform the erase operation on wl1~wl4 at -6.0V by the middle word line charge pump The number of times is also 3 times, and the erase operation performed on the edge word line will not affect the middle word line, and the edge word line and the middle word line complete the erase operation at the same time.

With reference to Fig. 2, have shown the schematic diagram inside the Nand flash memory of the embodiment of the present invention, the memory cell array in the Nand flash memory comprises 10 word lines, and address is respectively wl0, wl1, wl2, wl3, wl4, wl5, wl6, wl7, wl8, wl9, where wl0 and wl9 are edge word lines, wl1, wl2, wl3, wl4, wl5, wl6, wl7, and wl8 are middle word lines, and the edge word line charge pump provides operating voltage for wl0 and wl9, and the middle word line charges The pump provides operating voltage for wl2, wl3, wl4, wl5, wl6, wl7, wl8, the preset voltage is 6.5V.

If the Nand flash memory uses the same voltage -6.0V to perform the erase operation on the edge word line and the middle word line: wl0, wl1, wl2, wl3, wl4, wl5 after the programming operation is completed, the edge word line wl0 performs the erase operation. The number of erasing cycles is 6 times, and the middle word lines: wl1, wl2, wl3, wl4, wl5 need to perform the erasing operation for 3 times. According to the empirical value, the threshold voltage of wl0 is 6.82V after programming. The threshold voltage of wl1 is 6.32V, the threshold voltage of wl2 is 6.36V, the threshold voltage of wl3 is 6.43V, the threshold voltage of wl4 is 6.21V, the threshold voltage of wl5 is 6.44V, then the edge word line charge pump is -7.0V Perform the erase operation on wl0, and the middle word line charge pump still uses -6.0V to perform the erase operation on the middle word lines: wl1, wl2, wl3, wl4, and wl5. At this time, the number of erase cycles required for wl0 to perform the erase operation is 3 times, wl1, wl2, wl3, wl4, wl5 need to perform the erase operation for 3 times, wl0 and wl1, wl2, wl3, wl4, wl5 complete the erase operation at the same time, wl0 and the middle word line wl1, wl2 , wl3, wl4, and wl5 do not affect each other.

It should be said that the data enumerated in the above implementation are only simple data enumerated for better explaining the embodiment of the present invention, and do not represent the actual specific data of the Nand flash memory.

Fig. 3 shows the block diagram of a kind of device of controlling erase operation of the embodiment of the present invention, and this device is applied to Nandflash memory, and Nand flash memory comprises: memory cell array, voltage detection unit and charge pump, and memory cell array comprises: edge The word line and the middle word line, the edge word line is two word lines at the edge position of the memory cell array, the middle word line is a plurality of word lines except the two word lines at the edge position in the memory cell array, and the charge pump includes : Edge word line charge pump, the edge word line charge pump provides operating voltage for the edge word line, each word line includes a plurality of memory cells; the device for controlling the erasing operation includes:

The receiving instruction module 310 is configured to receive an erasing operation instruction, and the erasing operation instruction includes: the address of the storage unit required to perform the erasing operation;

Determining the judging module 320, configured to determine that the word line to which the address of the memory cell required to perform the erasing operation belongs is the target word line, and determine whether the target word line belongs to the edge word line;

A detection voltage module 330, configured to detect whether the threshold voltage of the edge word line where the target word line is located is less than a preset voltage through a voltage detection unit if the target word line belongs to an edge word line;

The voltage adjustment module 340 is configured to adjust the erase operation voltage for the target word line through the edge word line charge pump according to the preset voltage if the threshold voltage is greater than or equal to the preset voltage;

The executing operation module 350 is configured to execute an erasing operation corresponding to the erasing operation instruction on the edge word line where the target word line is located according to the adjusted erasing operation voltage.

Optionally, the charge pump further includes: an intermediate word line charge pump, the intermediate word line charge pump provides an operating voltage for the intermediate word line, and the device for controlling the erasing operation further includes:

The voltage supply module is used to provide an erase operation voltage for the edge word line through the edge word line charge pump if the threshold voltage is less than a preset voltage, and the erase operation voltage is the same as that provided by the middle word line charge pump for the erase The operating voltages are equal in magnitude.

Optionally, the device for controlling the erasing operation also includes:

The detection threshold module is used to detect the edge of the target word line through the voltage detection unit when the target word line belongs to the edge word line and the number of erasing cycles required to complete the erasing operation on the target word line is greater than the preset number of times. Whether the threshold voltage of the edge word line is lower than a predetermined voltage.

Optionally, the voltage adjustment module includes:

A determination sub-module is used to determine the adjustment range based on the preset voltage;

The adjustment sub-module is used to adjust the erasing operation voltage for the target word line through the edge word line charge pump according to the adjustment range.

The embodiment of the present invention also provides a kind of Nand flash memory, and this Nand flash memory comprises: memory cell array, voltage detection unit and charge pump, and memory cell array comprises: edge word line and middle word line, and edge word line is in memory cell The two word lines at the edge position of the array, the middle word line is a plurality of word lines in the memory cell array except the two word lines at the edge position, and the charge pump includes: the edge word line charge pump and the middle word line charge pump, the edge word line charge pump The word line charge pump provides the operating voltage for the edge word line, the middle word line charge pump provides the operating voltage for the middle word line, and each word line includes a plurality of memory cells; the Nand flash memory is used to perform any one of steps 101 to 105 described method.

Through the above-mentioned embodiments, when performing an erasing operation, the present invention judges whether the word line to which the memory cell that needs to perform the erasing operation belongs is an edge word line, and if it is an edge word line, then adjusts the charge pump that provides the operating voltage for the edge word line The power supply voltage increases the voltage difference between the gate voltage of the edge word line and the substrate, so that the edge word line can be erased faster and successfully, and reduces the number of erase cycles required for the edge word line to perform an erase operation , thereby reducing the impact on the middle word line, prolonging the service life of the entire memory cell array, and improving the reliability of the Nand flash memory operation.

Finally, it should also be noted that in this text, relational terms such as first and second etc. are only used to distinguish one entity or operation from another, and do not necessarily require or imply that these entities or operations, any such actual relationship or order exists. Also, herein, the terms "comprises," "comprising," or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article, or apparatus that includes a set of elements includes not only those elements, but also includes none. other elements specifically listed, or also include elements inherent in such a process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus comprising that element.

Embodiments of the present invention have been described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementations, and the above-mentioned specific implementations are only illustrative, rather than restrictive, and those of ordinary skill in the art will Under the enlightenment of the present invention, many forms can also be made without departing from the gist of the present invention and the protection scope of the claims, and these all belong to the protection of the present invention.

Claims (10)

1. a method for controlling erasing operation, it is characterized in that, described method is applied to Nand flash storage, and described Nand flash storage comprises: storage cell array, voltage detection unit and charge pump, and described storage cell array comprises: edge A word line and an intermediate word line, the edge word lines are the two word lines at the edge positions of the memory cell array, and the intermediate word lines are the two word lines at the edge positions in the memory cell array A plurality of word lines, the charge pump includes: an edge word line charge pump, the edge word line charge pump provides the edge word line with an erase operation voltage different from that of the middle word line, and each word line includes a plurality of storage unit; the method comprising: Receive an erase operation instruction, the erase operation instruction includes: the address of the storage unit that needs to perform the erase operation; Determining that the word line to which the address of the memory cell to be erased belongs belongs to the target word line, and judging whether the target word line belongs to the edge word line; If the target word line belongs to the edge word line, detecting whether the threshold voltage of the edge word line where the target word line is located is less than a preset voltage by the voltage detection unit; If the threshold voltage is greater than or equal to the preset voltage, adjusting an erase operation voltage for the target word line through the edge word line charge pump according to the preset voltage; According to the adjusted erasing operation voltage, the erasing operation corresponding to the erasing operation instruction is performed on the edge word line where the target word line is located. 2. The method according to claim 1, wherein the voltage value of the adjusted erase operation voltage satisfies a preset condition, and the preset condition is: for the same erase operation, where the target word line is located The number of erasing cycles required for performing the erasing operation on the edge word lines is less than or equal to the number of erasing cycles required for performing the erasing operation on the middle word lines. 3. The method according to claim 1, wherein the charge pump further comprises: an intermediate word line charge pump, the intermediate word line charge pump provides an operating voltage for the intermediate word line, and in the target word line line belongs to the edge word line, after the voltage detection unit detects whether the threshold voltage of the edge word line where the target word line is located is less than a preset voltage, the method further includes: If the threshold voltage is less than the preset voltage, the edge word line charge pump provides an erase operation voltage for the edge word line, and the erase operation voltage is equal to the intermediate word line charge pump. The erasing operation voltages provided by the word lines are equal in magnitude. 4. The method according to claim 1, wherein if the target word line belongs to the edge word line, whether the threshold voltage of the edge word line where the target word line is located is detected by the voltage detection unit less than a preset voltage, including: when the target word line belongs to the edge word line, and the number of erasing cycles required to complete the erasing operation on the target word line is greater than the preset number of times, passing the The voltage detection unit detects whether the threshold voltage of the edge word line where the target word line is located is lower than a preset voltage. 5. The method according to any one of claims 1-4, wherein, according to the preset voltage, adjusting the erase operation voltage for the target word line through the edge word line charge pump comprises: determining the adjustment range based on the preset voltage; According to the adjustment range, the erase operation voltage for the target word line is adjusted through the edge word line charge pump. 6. A device for controlling erasing operations, characterized in that, the device is applied to a Nand flash memory, and the Nand flash memory includes: a memory cell array, a voltage detection unit and a charge pump, and the memory cell array includes: an edge A word line and an intermediate word line, the edge word lines are the two word lines at the edge positions of the memory cell array, and the intermediate word lines are the two word lines at the edge positions in the memory cell array A plurality of word lines, the charge pump includes: an edge word line charge pump, the edge word line charge pump provides the edge word line with an erase operation voltage different from that of the middle word line, and each word line includes a plurality of storage unit; the device includes: The receiving instruction module is used to receive the erasing operation instruction, and the erasing operation instruction includes: the address of the storage unit required to perform the erasing operation; A determining and judging module, configured to determine that the word line to which the address of the memory cell to be erased belongs belongs to the target word line, and determine whether the target word line belongs to the edge word line; A detection voltage module, configured to detect whether the threshold voltage of the edge word line where the target word line is located is less than a preset voltage through the voltage detection unit if the target word line belongs to the edge word line; A voltage adjustment module, configured to adjust the erase operation voltage for the target word line through the edge word line charge pump according to the preset voltage if the threshold voltage is greater than or equal to the preset voltage; The executing operation module is configured to execute the erasing operation corresponding to the erasing operation instruction on the edge word line where the target word line is located according to the adjusted erasing operation voltage. 7. The device according to claim 6, wherein the charge pump further comprises: an intermediate word line charge pump, the intermediate word line charge pump provides an operating voltage for the intermediate word line, and the device further comprises : providing a voltage module, configured to provide an erase operation voltage for the edge word line through the edge word line charge pump if the threshold voltage is less than the preset voltage, and the erase operation voltage is the same as that of the middle word line The erase operation voltages provided by the charge pumps to the middle word lines are equal in magnitude. 8. The device according to claim 6, further comprising: A detection threshold module, configured to pass the voltage when the target word line belongs to the edge word line and the number of erasing cycles required to complete the erasing operation on the target word line is greater than a preset number of times The detection unit detects whether the threshold voltage of the edge word line where the target word line is located is lower than a preset voltage. 9. The device according to any one of claims 6-8, wherein the voltage adjustment module comprises: A determining submodule, configured to determine the adjustment range based on the preset voltage; The adjustment sub-module is used to adjust the erase operation voltage for the target word line through the edge word line charge pump according to the adjustment range. 10. A kind of Nand flash memory, it is characterized in that, described Nand flash memory comprises: memory cell array, voltage detection unit and charge pump, and described memory cell array comprises: edge word line and middle word line, described edge word line are two word lines at the edge positions of the memory cell array, the middle word lines are a plurality of word lines in the memory cell array except the two word lines at the edge positions, and the charge pump includes: A word line charge pump and an intermediate word line charge pump, the edge word line charge pump provides an operating voltage for the edge word line, the intermediate word line charge pump provides an operating voltage for the intermediate word line, each word line includes A plurality of storage units; the Nand flash memory is used to perform the method described in any one of claims 1-5.

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