CN105489246B - NOR flash memory and its repair method - Google Patents

Abstract

The invention provides a NOR flash memory and a repairing method thereof. The repairing method comprises the following steps: judging whether at least one spare memory block is unused; counting the programmed times of each memory block and the erased times of each memory block; judging whether the programmed times are not less than a first preset critical value or not and whether the erased times are not less than a second preset critical value or not; and when the programming times corresponding to the selected memory block of the memory blocks are not less than a first preset threshold or the erasing times are not less than a second preset threshold, replacing at least one spare memory block with the selected memory block.

Description

NOR flash memory and its repair method

technical field

The present invention relates to a NOR flash memory, and in particular to a repair method for a NOR flash memory.

Background technique

With the continuous evolution of flash memory manufacturing specifications, the decline in the durability of flash memory chips will be an important issue that must be faced under cost considerations. In NOR flash memory, its application environment is quite different from that of NAND flash memory. In consideration of cost, NOR flash memory does not have an external control chip to cooperate with. Therefore, it is difficult to increase the service life of NOR flash memory through complex algorithms.

Usually, NOR flash memory is used to store important data such as boot codes. And this type of data usually cannot tolerate any single bit error. Therefore, in the existing technology of NOR flash memory, it is necessary to apply the most rigorous method for production from the design end to the manufacturing end. However, with the evolution of manufacturing and cost considerations, it is becoming more and more difficult to make NOR flash memory satisfy all device characteristics. Therefore, how to effectively improve the performance of NOR flash memory is a major problem for designers in this field.

Contents of the invention

The invention provides a NOR flash memory and a repair method thereof to enhance the use efficiency of the NOR flash memory.

The repairing method of NOR flash memory of the present invention comprises judging whether there is at least one spare storage block unused; Counting a programmed number of times of each storage block and a wiped number of times of each storage block; judging that it is programmed Whether the number of times is not less than a first preset critical value, and whether the number of erasing times is not less than a second preset critical value; When the critical value is set or the erasing times are not less than a second preset critical value, at least one spare memory block is replaced with the selected memory block.

The NOR flash memory of the present invention includes a plurality of storage blocks, a plurality of spare storage blocks and a memory controller. The memory controller is coupled to the memory blocks and the spare memory blocks. The memory controller judges whether at least one of the spare memory blocks is unused, and counts the number of times each memory block is programmed and the number of times each memory block is erased. number of divisions. The memory controller also judges whether the number of times of being programmed is not less than a first preset threshold, and whether the number of times of erasing is not less than a second preset threshold. And when the number of times of being programmed corresponding to the selected memory block of the memory block is not less than the first preset threshold or the number of times of being erased is not less than the second preset threshold, the memory controller makes the spare memory block unused One of them is replaced with the selected memory block.

Based on the above, the present invention counts the programmed times and erased times of each memory block of the NOR flash memory, and when the programmed times or erased times of the memory blocks exceed the preset number of times limit, the corresponding The memory block and the spare memory block are replaced. Thereby, it is effectively ensured that the memory block in use is a memory block with high reliability, so as to maintain the data access quality of the NOR flash memory. Also, by providing spare memory blocks, the lifespan of NOR flash memory is also extended.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail with reference to the accompanying drawings.

Description of drawings

Fig. 1 depicts the repairing method of the NOR flash memory of an embodiment of the present invention;

FIG. 2A shows a repair method of a NOR flash memory according to another embodiment of the present invention;

FIG. 2B shows a repairing method of a NOR flash memory according to yet another embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating an implementation manner of replacement of a storage block and a spare storage block according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a NOR flash memory according to an embodiment of the present invention.

Explanation of reference signs:

S110～S140, S211～S219, S2110～S2111, S221～S229, S2210～S2211: the steps of the repair method;

A1～AM: storage block;

BA1～BAN: spare storage block;

AS: select the storage block;

400: NOR flash memory;

410: storage block;

420: spare storage block;

430: Memory controller.

Detailed ways

Please refer to FIG. 1 . FIG. 1 illustrates a repairing method of a NOR flash memory according to an embodiment of the present invention. Analyzing the application level of NOR flash memory, the more common one is the Basic Input Output System (BIOS) used to store boot codes. From the perspective of various electronic devices that NOR flash memory may be applied to, users of NOR flash memory do not perform programming (program) and erasing (erase) actions on NOR flash memory storage blocks. Usually, taking the boot code as an example, the main program will be placed on a memory block with a fixed address, and the main program will only be changed when the firmware is updated. That is to say, the probability of program erasure that may occur in the memory block occupied by the main program is relatively low.

It can be seen from the above description that only some of the storage blocks of NOR flash memory used for calculation and recording will be programmed and erased more often, that is, for these frequently programmed and erased operations Repairing the storage block can effectively improve the overall lifespan of the NOR flash memory.

Therefore, the present invention adds one or more spare storage blocks to the storage block to cooperate with the repairing operation. Wherein, in step S110, it is first determined whether there is at least one spare storage block that is not used. When it is determined in step S110 that one or more spare storage blocks are not used, it means that the NOR flash memory repair operation can be performed. Accordingly, in step S120 , a counting operation of the number of times the programming operation and the erasing operation are performed for each memory block is performed. The above-mentioned counting operation in step S120 is performed while the NOR flash memory is being used. Wherein, each memory block that has been programmed can generate a corresponding count value of programmed times, and each memory block that has been erased can generate a corresponding count value of erased times. Of course, for the memory block that has been erased and programmed, a corresponding count value of programmed times and a count value of erased times is generated.

Regarding the implementation details of step S120, for example, when the NOR flash memory receives a programming command to perform the first programming action on the memory block A1, the address Fi of the memory block A1 can be recorded in a storage device, and Set the number of times corresponding to the memory block A1 to be programmed as 1. When there is a subsequent programming command to perform a programming operation on the memory block A1, since the address Fi of the memory block A1 has been recorded in the storage device, Therefore, the NOR flash memory can directly increment (+1) the programmed times corresponding to the memory block A1. Similarly, when the NOR flash memory receives a programming command to erase the memory block A1 for the first time, the address Fi of the memory block A1 can be recorded in a storage device, and the corresponding address of the memory block A1 can be set. The number of erasures is 1. When there is another programming command to erase the memory block A1, the address Fi of the memory block A1 has been recorded in the storage device. Therefore, the NOR flash memory can directly make the memory block A1 erase. The erasure count corresponding to the block A1 is incremented (+1).

In step S130, the program times and erase times of each memory block are determined. Wherein, the programmed times of each memory block can be compared with a first preset threshold, and the erased times of each memory block can be compared with a second preset threshold. The above-mentioned first preset threshold value and the second preset threshold value can be set by the designer according to the characteristics of the memory block. Wherein, the first preset critical value and the second preset critical value may be the same or different.

In step S140, when the programmed times of the storage block is greater than or equal to the first preset threshold, it means that the programmed times of the storage block has exceeded the safe use range. The NOR flash memory can perform the replacement operation of the storage block and the spare storage block, so as to complete the repair operation of the NOR flash memory. Similarly, when the number of erasing times of the storage block is greater than or equal to the second preset critical value, it means that the number of erasing of the storage block has exceeded the safe use range, and the NOR flash memory can also execute the storage area block and spare storage block, and thereby complete the repair operation of NOR flash memory.

Regarding the implementation details of step S140, for example, when the NOR flash memory determines that the number of times the memory block A1 has been programmed is greater than or equal to the first preset threshold value, it can select one of the unused spare memory blocks One of them (the spare memory block B1) is used to replace the memory block A1. Specifically, assuming that under the initial conditions, the logical address LA1 corresponds to the physical address of the storage block A1, and when the replacement operation of the storage block A1 and the spare storage block B1 is performed, the logical address LA1 is changed to correspond to the spare The physical address of block B1 is stored.

Incidentally, after the replacement operation of the memory block A1 and the spare memory block B1 is completed, the address of the memory block A1 recorded in the storage device and the corresponding times of being programmed and times of being erased can be give up.

In addition, each spare storage block in the embodiment of the present invention has a corresponding usage status mark. When each spare memory block is not used and is replaced with any memory block, its corresponding usage state flags are all indicated as unused state. When the spare storage block (for example, the spare storage block B1 ) is used to replace a storage block, the use status flag of the spare storage block B1 can be set as a used state.

That is to say, when checking the use status of the spare storage block as in step S110, it is only necessary to simply check all the use status flags. If at least one of the usage status flags indicates an unused status, it means that the repair operation of the storage block can still be performed. On the contrary, if all the usage status flags are indicated as being used, it means that the repair operation of the storage block cannot be performed.

The above usage status flag can be expressed as an unused status or a used status by using a logical value. For example, when the use state flag is equal to a logic value of 1, it may indicate that the corresponding spare storage block is in an unused state, and when the use state flag is equal to a logic value of 0, it may indicate that the corresponding spare storage block is in a used state. Of course, the corresponding relationship between the logical value and the unused state and the used state can be changed arbitrarily, and the above examples are not intended to limit the present invention.

Please refer to FIG. 2A . FIG. 2A illustrates a NOR flash memory repair method according to another embodiment of the present invention. In step S211, a programming command is received, and in step S212, the address Fi of the memory block to be programmed is stored according to the received programming command. In step S213, it is determined whether there is at least one spare storage block that is not used. If the determination result of step S213 is yes, proceed to step S214 to perform program and verify actions. By counting the times L1 of programming of the memory block, and comparing the number of times L1 of programming of the memory block with a preset threshold N1 in step S215 . When the times L1 of being programmed is less than N1, it means that the storage block can continue to be provided for programming, and when the verifying operation in step S216 is passed, the programming operation ends. In contrast, when the verification action in step S216 fails, step S214 needs to be re-executed to perform the programmed action again.

Based on the above, if it is determined in step S215 that the number of times L1 of the memory block being programmed is greater than or equal to the preset threshold N1, then proceed to step S217 to record the address Fi of the memory block, and start the replacement of the spare memory block action. After the memory block is replaced by the spare memory block, the memory block can be continuously provided for programming and verification (step S219 ). Moreover, step S2110 judges whether the number of memory block programming and verification operations has exceeded the set maximum number of times. If the result of the judgment has exceeded the maximum number of times (maximum security value), it indicates that the programming verification operation has failed. In contrast, if the result of the judgment does not exceed the maximum number of times, and step S2111 judges that the programming and verification actions are passed, it means that the programming action is completed. If the judging result does not exceed the maximum number of times, and step S2111 judges that the programming and verification actions are not passed, re-execute step S219.

On the other hand, if the judgment result of step S213 shows that all spare storage blocks have been used, then the storage block cannot be repaired. In this state, the memory block can only be programmed and verified until the number of times the memory block has been programmed exceeds the maximum security value.

Please refer to FIG. 2B . FIG. 2B illustrates a NOR flash memory repair method according to another embodiment of the present invention. In step S221, an erasing command is received, and in step S222 it is judged whether at least one spare storage block is unused, if the judgment result of step S222 is yes, step S223 is executed and it is judged whether there is a spare storage block that has been used can. When a spare memory block is enabled, step S226 can be executed to start replacement of the spare memory block according to the address Fi of the memory block.

If the determined result of step S223 is negative, proceed to step S224. Step S224 performs erase and verify operations. By counting the erasing times L2 of the memory block, the erasing times L2 of the memory block is compared with a preset threshold N2 in step S225 . When the number of erasing times L2 is less than N2, it means that the storage block can continue to be provided for erasing, and when the verifying action in step S227 is passed, the programming action is ended. In contrast, when the verification action in step S229 fails, step S224 needs to be re-executed to perform the programmed action again.

Based on the above, if it is determined in step S225 that the number of times L2 of the memory block being erased is greater than or equal to the preset critical value N2, then step S226 is performed to start the backup storage according to the address Fi of the memory block stored in step S223. block replacement.

On the other hand, if the determination result of step S222 shows that all the spare storage blocks have been used, then the storage block cannot be repaired. In this state, only the storage block can be programmed and verified (step S229 ), until the number of times the storage block has been programmed exceeds the maximum security value.

Wherein, step S2210 judges whether the times of erasing and verifying the storage block have exceeded the set maximum times, and if the judgment result has exceeded the maximum times (maximum security value), it indicates that the programmed verification has failed. In contrast, if the result of the judgment does not exceed the maximum number of times, and step S2211 judges that the programming and verification actions are passed, it means that the programming action is completed. If the judging result does not exceed the maximum number of times, and step S2111 judges that the programming and verification actions are not passed, re-execute step S229.

Regarding the replacement of the storage block and the spare storage block, please refer to FIG. 3 , wherein FIG. 3 is a schematic diagram of an implementation manner of the replacement of the storage block and the spare storage block according to the embodiment of the present invention. In FIG. 3, the NOR flash memory includes a plurality of memory blocks A1-AM and spare memory blocks BA1-BAN. Wherein, when the spare memory block BA1 is in an unused state, and the erasing times of the selected memory block AS are not less than the second preset threshold or the times of being programmed are not less than the first preset threshold, the spare storage The block BA1 can replace the selected storage block AS, and make the spare storage block BA1 a memory block for storing data. The original selected storage block AS is left idle.

Please refer to FIG. 4 below. FIG. 4 is a schematic diagram of a NOR flash memory according to an embodiment of the present invention. The NOR flash memory 400 includes a memory block 410 , a spare memory block 420 and a memory controller 430 . There are multiple storage blocks with the same storage capacity in the storage block 410 . The spare storage block 420 includes at least one storage block. The memory controller 430 is a logic circuit built in the NOR flash memory 400 . The memory controller 430 can execute each step of the repair method as shown in FIG. 1 , and thereby perform repair operations.

The action details of each step performed by the memory controller 430 have been described in detail in the above-mentioned embodiments and implementations, and will not be described in detail below.

To sum up, the present invention sets a spare storage block in the NOR flash memory, and by counting the number of times the storage block is programmed or erased, the replacement action between the spare storage block and the storage block is performed. This completes the repair action of the NOR flash memory and improves the service life of the NOR flash memory.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (12)

1. a kind of method for repairing and mending of NOR flash memory, which is characterized in that the NOR flash memory has most memory blocks, including：

Judge whether that there is an at least slack storage block to be not used by；

Sequencing action, and the accumulative respectively memory block in corresponding verification baulk are carried out for the respectively memory block One is programmed number, alternatively, carrying out erasing action for the respectively memory block, and tires out in corresponding verification baulk Count the respectively memory block one is erased number；

Differentiate this be programmed number whether not less than one first preset critical and this whether be erased number not less than one the Two preset criticals；And

When the one of those memory blocks choose corresponding this of memory block be programmed number be not less than first preset critical Or this be erased number not less than second preset critical when, making this, at least a slack storage block chooses memory block with this Into line replacement.

2. the method for repairing and mending of NOR flash memory according to claim 1, which is characterized in that count the quilt of the respectively memory block The step of sequencing number includes：

Address according to the respectively memory block that programmed command record is programmed；And

In the presence of when at least slack storage block being not used by, the respectively memory block being incrementally programmed is corresponding This is programmed number.

3. the method for repairing and mending of NOR flash memory according to claim 2, which is characterized in that when this chooses memory block corresponding When this is programmed number not less than first preset critical, this chooses the physical address of memory block to correspond to one logically Location；And

When this chooses corresponding this of memory block to be programmed number not less than first preset critical, the logical address quilt The corresponding physical address to an at least slack storage block of change.

4. the method for repairing and mending of NOR flash memory according to claim 1, which is characterized in that count the quilt of the respectively memory block Erase number the step of include：

The address for the respectively memory block that command record is erased of erasing according to one；And

In the presence of when at least slack storage block being not used by, the respectively memory block being incrementally programmed is corresponding This is erased number.

5. the method for repairing and mending of NOR flash memory according to claim 4, which is characterized in that when this chooses memory block corresponding When this is erased number not less than second preset critical, this chooses the physical address of memory block to correspond to one logically Location；And

When this chooses corresponding this of memory block to be erased number not less than second preset critical, which is become The more corresponding physical address to an at least slack storage block.

6. the method for repairing and mending of NOR flash memory according to claim 1, which is characterized in that an at least slack storage block pair Answer a use state mark, and judge whether have this include the step of at least a slack storage block is not used by：

Check that the corresponding use state of an at least slack storage block marks whether to be designated as being not used by state.

7. a kind of NOR flash memory, which is characterized in that including：

Most memory blocks；

Most slack storage blocks；And

One Memory Controller couples those memory blocks and those slack storage blocks, which judges should Whether there is an at least slack storage block to be not used by a little slack storage blocks, which is directed to the respectively storage Block carries out sequencing action, and adds up the one of the respectively memory block in corresponding verification baulk and be programmed number, Alternatively, the Memory Controller carries out erasing action for the respectively memory block, and tire out in corresponding verification baulk Respectively the memory block one is erased number to meter, which simultaneously differentiates that whether this is programmed number the not less than 1 One preset critical and this be erased number whether be not less than one second preset critical, and when those memory blocks a choosing Corresponding this of middle memory block be programmed number not less than first preset critical or this be erased number not less than this When two preset criticals, which makes those slack storage blocks one of be not used by choose storage with this Block is into line replacement.

8. NOR flash memory according to claim 7, which is characterized in that the Memory Controller is remembered according to a programmed command The address for the respectively memory block being programmed is recorded, and in the presence of at least slack storage block being not used by, is incremented by Corresponding this of the respectively memory block being programmed is programmed number.

9. NOR flash memory according to claim 8, which is characterized in that when this chooses corresponding this of memory block to be programmed When number is not less than first preset critical, this chooses the physical address of memory block to correspond to a logical address, when the choosing When corresponding this of middle memory block is programmed number not less than first preset critical, which changes this and patrols Address is collected to the physical address of an at least slack storage block.

10. NOR flash memory according to claim 8, which is characterized in that the Memory Controller is erased command record according to one The address for the respectively memory block being erased, and in the presence of when at least slack storage block being not used by, it is incremented by quilt Corresponding this of the respectively memory block of sequencing is erased number.

11. NOR flash memory according to claim 10, which is characterized in that when this chooses corresponding this of memory block to be erased When number is not less than second preset critical, this chooses the physical address of memory block to correspond to a logical address, when the choosing When corresponding this of middle memory block is erased number not less than second preset critical, which changes the logic Address is corresponded to the physical address of an at least slack storage block.

12. NOR flash memory according to claim 7, which is characterized in that an at least slack storage block corresponds to one and uses shape State marks, and the Memory Controller inspection corresponding use state of an at least slack storage block marks whether to be designated as It is not used by state.