System and method for implementing super word line zones in a memory device

• US 10,223,022 B2
• Filed: 01/27/2017
• Issued: 03/05/2019
• Est. Priority Date: 01/27/2017
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Syu, Meiman Lin, Sprouse, Steven, Stoev, Kroum, Vasudeva, Satish
• Primary Examiner(s): Nguyen, Steve N
• Application Number:
  US15/418,455
• Publication Number:
  US 20180217892A1
• Time in Patent Office: 767 Days
• CPC Class Codes: G06F 11/1016 Error in accessing a memory location, i.e. addressing error
• CPC Class Codes: G06F 11/104 using arithmetic codes, i.e. codes which are preserved during operation, e.g. modulo 9 or 11 check
• CPC Class Codes: G06F 11/1048 using arrangements adapted for a specific error detection or correction feature
• CPC Class Codes: G06F 11/1072 in multilevel memories
• CPC Class Codes: G06F 2212/7208 Multiple device management, e.g. distributing data over multiple flash devices
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G11C 29/025 in signal lines
• CPC Class Codes: G11C 29/44 Indication or identification of errors, e.g. for repair
• CPC Class Codes: G11C 29/52 Protection of memory contents; Detection of errors in memory contents
• CPC Class Codes: G11C 29/883 using a single defective memory device with reduced capacity, e.g. half capacity

Abstract

A set of superblocks can be constructed by a memory controller employing good blocks and partially bad blocks in a plurality of memory access units. Each functional memory access unit among the plurality of memory access units contributes a single block that is a good block or a partially bad block to each superblock. The memory controller can further construct a set of super word line zones within each superblock in the set of superblocks. Each block within a superblock contributes a good word line zone to each super word line zone. Upon encounter of a program error at run time, the super word line zones within the superblock may be modified to continue running the program employing modified super word line zones for the superblock.

Claims

1. A data storage system comprising a memory controller that controls operation of a plurality of memory access units, wherein the memory controller is configured to perform steps of:

classifying each block within the plurality of memory access units into good blocks, partially bad blocks, and bad blocks, wherein the good blocks include only good word line zones, each of the partially bad blocks includes at least one, and not more than N, bad word line zones, and each of the bad blocks including more than N bad word line zones, wherein N is a positive integer; and

constructing a set of superblocks employing the good blocks and the partially bad blocks, wherein;

the memory controller is configured to construct a set of super word line zones within each superblock in the set of superblocks, wherein each block within the superblock contributes a good word line zone to each super word line zone within a predominant subset of the set of super word line zones;

the memory controller is configured to determine whether to modify super word line zones within the superblock or to initiate garbage collection upon encounter of a program error at the superblock; and

upon encounter of the program error during execution of a program at the superblock, the memory controller is configured to;

determine a total number of operational partially bad blocks that have at least one, and not more than (N+P), bad word line zones within the superblock, wherein P is a first non-negative integer; and

determine whether the total number of operational partially bad blocks exceeds M+Q, wherein M is a maximum number M for a total number of partially bad blocks in any single superblock during construction of the set of superblocks, and Q is a second non-negative integer, and

wherein each of the plurality of memory access units comprises a single NAND or NOR flash memory integrated circuit die, a plurality of NAND or NOR flash memory integrated circuit dies, or a plane of a NAND or NOR flash memory integrated circuit die containing multiple planes.

2. The data storage system of claim 1, wherein:

the memory controller is configured to proceed with modification of the super word line zones within the superblock only when a set of conditions is met, wherein the set of conditions comprises a condition that the total number of operational partially bad blocks that have one to (N+P) bad word line zones within the superblock does not exceed M+Q; and

during and after modification of the super word line zones within the superblock, the memory controller is configured;

to renumber, within each block with an increased count for any bad word line zone after the program error, each good word line zones;

to redefine a subset of the super word line zones within the superblock; and

to continue running the program employing modified super word line zones for the superblock.

3. The data storage system of claim 1, wherein:

the memory controller is configured to proceed with garbage collection when the total number of operational partially bad blocks that have one to (N+P) bad word line zones within the superblock exceeds M+Q; and

at least one of P and Q is a positive integer.

4. A method of operating a data storage system comprising a memory controller that controls operation of a plurality of memory access units, wherein each of the plurality of memory access units comprises a single NAND or NOR flash memory integrated circuit die, a plurality of NAND or NOR flash memory integrated circuit dies, or a plane of a NAND or NOR flash memory integrated circuit die containing multiple planes, the method comprising steps of:

classifying, by employing the memory controller, each block within the plurality of memory access units into good blocks, partially bad blocks, and bad blocks, wherein good blocks include only good word line zones, each of the partially bad blocks includes at least one, and not more than N, bad word line zones, and each of the bad blocks including more than N bad word line zones, wherein N is a positive integer;

constructing, by employing the memory controller, a set of superblocks employing the good blocks and the partially bad blocks;

constructing, by employing the memory controller, a set of super word line zones within each superblock in the set of superblocks, wherein each block within the superblock contributes a good word line zone to each super word line zone within a predominant subset of the set of super word line zones;

determining, by employing the memory controller, whether to modify super word line zones within the superblock or to initiate garbage collection upon encounter of a program error at the superblock; and

performing, upon encounter of the program error during execution of a program at the superblock, a set of steps comprising;

a first step of determining, by employing the memory controller, a total number of operational partially bad blocks that have at least one, and not more than (N+P), bad word line zones within the superblock, wherein P is a first non-negative integer; and

a second step of determining, by employing the memory controller, whether the total number of operational partially bad blocks exceeds M+Q, wherein M is a maximum number M for a total number of partially bad blocks in any single superblock during construction of the set of superblocks, and Q is a second non-negative integer.

5. The method of claim 4, further comprising:

proceeding, by employing the memory controller, with modification of the super word line zones within the superblock only when a set of conditions is met, wherein the set of conditions comprises a condition that the total number of operational partially bad blocks that have one to (N+P) bad word line zones within the superblock does not exceed M+Q; and

performing, during and after modification of the super word line zones within the superblock, by employing the memory controller a set of steps including;

a first step of renumbering, within each block with an increased count for any bad word line zone after the program error, each good word line zones;

a second step of redefining a subset of the super word line zones within the superblock; and

a third step of continuing to run the program employing modified super word line zones for the superblock.