Storage device
A storage device includes a nonvolatile memory device and a controller. A nonvolatile memory device includes a plurality of memory blocks. Each of the plurality of memory blocks is divided into a plurality of zones and is formed on a substrate. Each of the plurality of zones comprises one or more word lines. A controller performs a reliability verification read operation on a first zone of the plurality of zones of a memory block selected from the plurality of memory blocks if a number of read operations performed on the first zone reaches a first threshold value and performs the reliability verification read operation on a second zone of the plurality of zones of the selected memory block if a number of read operations performed on the second zone reaches a second threshold value.
1. A storage device comprising:
a nonvolatile memory device comprising a plurality of memory blocks,
wherein each of the plurality of memory blocks is divided into a plurality of zones and is formed on a substrate, and
wherein each of the plurality of zones comprises one or more word lines; and
a controller configured to:
perform a reliability verification read operation on a first zone of the plurality of zones of a memory block selected from the plurality of memory blocks if a number of read operations performed on the first zone reaches a first threshold value; and
perform the reliability verification read operation on a second zone of the plurality of zones of the selected memory block if a number of read operations performed on the second zone reaches a second threshold value.
2. The storage device of claim 1 ,
wherein the controller is further configured to:
detect a number of error bits of data read from the first zone through the reliability verification read operation on the first zone, and
perform a read reclaim operation on data stored in the first zone based on a number of error bits.
3. The storage device of claim 1 ,
wherein the first zone of the plurality of zones is closer to the substrate than the second zone of the plurality of zones, and
wherein the second threshold value is greater than the first threshold value.
4. The storage device of claim 1 ,
wherein the first zone and the second zone of each of the selected memory block are stacked in a direction perpendicular to the substrate.
5. The storage device of claim 4 ,
wherein a distance between the first zone and the substrate is shorter than a distance between the second zone and the substrate.
6. The storage device of claim 1 ,
wherein the first zone of the plurality of zones is closer to the substrate than the second zone of the plurality of zones, and
wherein the controller is further configured to perform the reliability verification read operation on the first zone more frequently than to perform the reliability verification read operation on the second zone.
7. The storage device of claim 1 ,
wherein the controller is further configured to:
detect a number of error bits of data read from the second zone through the reliability verification read operation on the second zone, and
perform a read reclaim operation for moving data stored in the selected memory block to another memory block based on a number of error bits.
8. A storage device comprising:
a nonvolatile memory device comprising a plurality of memory blocks,
wherein each of the plurality of memory blocks is divided into a plurality of zones and is formed on a substrate, and
wherein each of the plurality of zones comprises one or more word lines; and
a controller configured to:
perform a reliability verification read operation on a first zone of the plurality of zones of a memory block selected from the plurality of memory blocks if a number of read operations performed on the first zone reaches a first threshold value; and
perform the reliability verification read operation on a second zone of the plurality of zones of the selected memory block if a number of read operations performed on the second zone reaches a second threshold value,
wherein the controller is configured to classify the plurality of memory blocks into a plurality of new zones based on a number of program/erase cycles of the selected memory block.
9. The storage device of claim 8 ,
wherein the controller is configured to set new threshold values to perform the reliability verification read operation on the plurality of new zones.
10. The storage device of claim 8 ,
wherein the controller is configured to perform the reliability verification read operation on each of the plurality of new zone more frequently than to perform the reliability verification read operation on each of the plurality of zones.
11. The storage device of claim 8 ,
wherein if a number of program/erase cycles of the selected memory block reaches a reference value, the controller is configured to set the plurality of new zones based on a degree of deterioration of word lines of the selected memory block.
12. The storage device of claim 11 ,
wherein the controller is configured to measure the degree of deterioration based on a temperature, a program speed, and bit error rate of the word lines of the selected memory block.
13. A storage device comprising:
a nonvolatile memory device including a plurality of word lines vertically stacked on a substrate,
wherein each of the plurality of word lines is associated with one of a plurality of zones divided according to a height of each of the plurality of word lines from the substrate; and
a controller comprising a count management unit storing a plurality of threshold values each of which is associated with one of the plurality of zones, generating a plurality of read counts by counting a read command for each of the plurality of zones and performing a reliability verification read operation on one or more word lines associated with a first zone of the plurality of zones if a read count of the first zone is greater than a threshold value of the first zone.
14. The storage device of claim 13 ,
wherein the controller further comprising:
an error correction code (ECC) circuit determining whether data read from each of the one or more word lines associated with the first zone in the reliability verification read operation is correctable; and
a reclaim management unit performing a read reclaim operation on a first word line of the one or more word lines associated with the first zone if the first word line is determined as uncorrectable by the ECC circuit.
15. The storage device of claim 13 ,
wherein the nonvolatile memory device includes a security area for storing information of a bad area, and
wherein zone information of the plurality of zones is stored in the security area of the nonvolatile memory device.
16. The storage device of claim 13 ,
wherein if a first zone of the plurality of zones is closer to the substrate than a second zone of the plurality of zones, a first threshold value of the plurality of threshold values associated with the second zone is greater than a first threshold value of the plurality of threshold values associated with the first zone.
17. The storage device of claim 13 ,
wherein the nonvolatile memory device further comprises a pillar penetrating the plurality of word lines and having a decreasing width toward the substrate.