# US 2021/0240385 A1 · Management of write operations in a non-volatile memory device using a variable pre-read voltage level > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0240385 A1 - Document ID: US20210240385A1 - Status: Published application - Kind: A1 - Application number: 16/777,766 - Filed: 2020-01-30 - Published: 2021-08-05 - Earliest claimed: 2020-01-30 - Assignees: Micron Technology, Inc. - Applicants: Micron Technology, Inc. - Inventors: Ying Yu Tai; Jiangli Zhu - Web page: https://patentgrep.com/patent/US20210240385A1 ## CPC - G06F 3/0659: {Command handling arrangements, e.g. command buffers, queues, command scheduling} - G11C 16/10: Programming or data input circuits - G06F 3/0604: {Improving or facilitating administration, e.g. storage management} - G06F 3/0619: {in relation to data integrity, e.g. data losses, bit errors} - G06F 3/0653: {Monitoring storage devices or systems} - G06F 3/0679: {Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]} - G11C 11/5628: {Programming or writing circuits; Data input circuits} - G11C 16/3459: {Circuits or methods to verify correct programming of nonvolatile memory cells} - G11C 16/349: {Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles} - G11C 16/0483: {comprising cells having several storage transistors connected in series} - G11C 2207/2263: Write conditionally, e.g. only if new data and old data differ - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G11C: STATIC STORES (semiconductor memory devices H10B) ## Abstract A processing device, operatively coupled with a memory device, is configured to receive a write request identifying data to be stored in a segment of the memory device. The processing device determines a write-to-write (W2W) time interval for the segment and determines whether the W2W time interval falls within a first W2W time interval range, the first W2W time interval range corresponds to a first pre-read voltage level. Responsive to the W2W time interval for the segment falling within the first W2W interval range, the processing device performs a pre-read operation on the segment using the first pre-read voltage level. The processing device identifies a subset of the data to be stored in the segment comprising bits of data that are different than corresponding bits of the data stored in the segment. The processing device further performs a write operation to store the subset of the data in the segment. ## Claims ### Claim 1 A system comprising: a memory device; and a processing device, operatively coupled with the memory device, to perform operations comprising: receiving a write request from a host system, the write request identifying data to be stored in a segment of the memory device; determining a write-to-write time interval for the segment of the memory device; determining whether the write-to-write time interval for the segment falls within a first write-to-write time interval range of a plurality of write-to-write time interval ranges for the memory device, wherein the first write-to-write time interval range represents a first plurality of write-to-write time intervals corresponding to a first pre-read voltage level; responsive to the write-to-write time interval for the segment falling within the first write-to-write time interval range, performing a pre-read operation on the segment of the memory device using the first pre-read voltage level to determine data currently stored in the segment; identifying a subset of the data identified in the write request to be stored in the segment of the memory device, wherein the subset of the data represents bits of data that are different than corresponding bits of the data currently stored in the segment and read during the pre-read operation; and performing a write operation to store the subset of the data in the segment of the memory device. ### Claim 2 (depends on 1) The system of claim 1, wherein determining the write-to-write time interval for the segment of the memory device comprises: reading a timestamp associated with the data in the segment of the memory device, the timestamp indicating a last time when data was written in the segment; and determining the write-to-write time interval as the time elapsed since the timestamp. ### Claim 3 (depends on 1) The system of claim 1, wherein the segment of the memory device comprises a plurality of data units, wherein a data unit comprises a smallest amount of memory on which a write operation is performed. ### Claim 4 (depends on 3) The system of claim 3, wherein the write-to-write time interval for the segment is determined based on a timestamp associated with a data unit of the plurality of data units of the segment, wherein the data unit is a most recently written data unit of the plurality of data units. ### Claim 5 (depends on 1) The system of claim 1, wherein the processing device is further to perform operations comprising: responsive to the write-to-write time interval for the segment not falling within the first write-to-write time interval range, performing the pre-read operation on the segment of the memory device using a second pre-read voltage level associated with a second write-to-write time interval range, wherein the second write-to-write time interval range represents a second plurality of write-to-write time intervals corresponding to the second pre-read voltage level. ### Claim 6 (depends on 1) The system of claim 1, wherein the first pre-read voltage level is a lowest pre-read voltage level of a plurality of pre-read voltage levels associated with the memory device. ### Claim 7 (depends on 1) The system of claim 1, wherein identifying the subset of the data to be stored at the segment of the memory device comprises: comparing a first set of bits of the data currently stored in the segment and read during the pre-read operation with a second set of bits of the data identified in the write request to be stored in the segment of the memory device; and marking bits of the second set of bits that do not match corresponding bits of the first set of bits as the subset of the data to be stored at the segment. ### Claim 8 A method comprising: receiving a write request from a host system, the write request identifying data to be stored in a segment of a memory device; determining a write-to-write time interval for the segment of the memory device; determining whether the write-to-write time interval for the segment falls within a first write-to-write time interval range of a plurality of write-to-write time interval ranges for the memory device, wherein the first write-to-write time interval range represents a first plurality of write-to-write time intervals corresponding to a first pre-read voltage level; responsive to the write-to-write time interval for the segment falling within the first write-to-write time interval range, performing a pre-read operation on the segment of the memory device using the first pre-read voltage level to determine data currently stored in the segment; identifying a subset of the data identified in the write request to be stored in the segment of the memory device, wherein the subset of the data represents bits of data that are different than corresponding bits of the data currently stored in the segment and read during the pre-read operation; and performing a write operation to store the subset of the data in the segment of the memory device. ### Claim 9 (depends on 8) The method of claim 8, wherein determining the write-to-write time interval for the segment of the memory device further comprises: reading a timestamp associated with the data in the segment of the memory device, the timestamp indicating a last time when data was written in the segment; and determining the write-to-write time interval as the time elapsed since the timestamp. ### Claim 10 (depends on 8) The method of claim 8, wherein the segment of the memory device comprises a plurality of data units, wherein a data unit comprises a smallest amount of memory on which a write operation is performed. ### Claim 11 (depends on 10) The method of claim 10, wherein the write-to-write time interval for the segment is determined based on a timestamp associated with a data unit of the plurality of data units of the segment, wherein the data unit is a most recently written data unit of the plurality of data units. ### Claim 12 (depends on 8) The method of claim 8 further comprising: responsive to the write-to-write time interval for the segment not falling within the first write-to-write time interval range, performing the pre-read operation on the segment of the memory device using a second pre-read voltage level associated with a second write-to-write time interval range, wherein the second write-to-write time interval range represents a second plurality of write-to-write time intervals corresponding to the second pre-read voltage level. ### Claim 13 (depends on 8) The method of claim 8, wherein the first pre-read voltage level is a lowest pre-read voltage level of a plurality of pre-read voltage levels associated with the memory device. ### Claim 14 (depends on 8) The method of claim 8, wherein identifying the subset of the data to be stored at the segment of the memory device further comprises: comparing a first set of bits of the data currently stored in the segment and read during the pre-read operation with a second set of bits of the data identified in the write request to be stored in the segment of the memory device; and marking bits of the second set of bits that do not match corresponding bits of the first set of bits as the subset of the data to be stored at the segment. ### Claim 15 A non-transitory computer-readable storage medium comprising instructions that, when executed by a processing device, cause the processing device to: perform a pre-read operation on a segment of a memory device using a first pre-read voltage level to identify first data stored in the segment of the memory device, wherein the pre-read voltage level satisfies a pre-read voltage level criterion; compare the first data stored in the segment of the memory device and read during the pre-read operation to second data associated with a write operation to be performed on the segment of the memory device to identify at least a portion of the second data that is different than the first data; and write at least the portion of the second data associated with the write operation to the segment of the memory device. ### Claim 16 (depends on 15) The non-transitory computer-readable storage medium of claim 15, wherein the pre-read voltage level criterion pertains to a write-to-write time interval for the segment of the memory device, and wherein determining that the pre-read voltage level satisfies the pre-read voltage level criterion comprises determining that the write-to-write time interval for the segment falls within a first write-to-write interval range of a plurality of write-to-write interval ranges for the memory device, wherein the first write-to-write interval range represents a first plurality of write-to-write time intervals corresponding to the first pre-read voltage level. ### Claim 17 (depends on 16) The non-transitory computer-readable storage medium of claim 16, wherein to determine the write-to-write time interval for the segment of the memory device, the processing device is further to: read a timestamp associated with the data in the segment of the memory device, the timestamp indicating a last time when data was written in the segment; and determine the write-to-write time interval as the time elapsed since the timestamp. ### Claim 18 (depends on 15) The non-transitory computer-readable storage medium of claim 15, wherein the segment of the memory device comprises a plurality of data units, wherein a data unit comprises a smallest amount of memory on which a write operation is performed. ### Claim 19 (depends on 15) The non-transitory computer-readable storage medium of claim 15, wherein the first write-to-write time interval range overlaps with the second write-to-write time interval range. ### Claim 20 (depends on 17) The non-transitory computer-readable storage medium of claim 17, wherein to identify the subset of the data to be stored at the segment of the memory device, the processing device is further to: compare a first set of bits of the data currently stored in the segment and read during the pre-read operation with a second set of bits of the data identified in the write request to be stored in the segment of the memory device; and mark bits of the second set of bits that do not match corresponding bits of the first set of bits as the subset of the data to be stored at the segment.