U.S. patent application number 17/008225 was filed with the patent office on 2022-03-03 for voltage offset bin selection by die group for memory devices.
The applicant listed for this patent is Micron Technology, Inc.. Invention is credited to Mustafa N. Kaynak, Larry J. Koudele, Shane Nowell, Vamsi Pavan RAYAPROLU, Michael Sheperek.
Application Number | 20220068396 17/008225 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-03 |
United States Patent
Application |
20220068396 |
Kind Code |
A1 |
RAYAPROLU; Vamsi Pavan ; et
al. |
March 3, 2022 |
VOLTAGE OFFSET BIN SELECTION BY DIE GROUP FOR MEMORY DEVICES
Abstract
One or more blocks at the memory device are programed. The one
or more blocks are associated with a block family and with one or
more dice of a die group. A voltage offset bin associated with the
die group and the block family is determined based on a subset of
dice of the die group. Metadata associated with the memory device
is appended to include a record associating the die group and the
block family with the voltage offset bin.
Inventors: |
RAYAPROLU; Vamsi Pavan; (San
Jose, CA) ; Kaynak; Mustafa N.; (San Deigo, CA)
; Sheperek; Michael; (Longmont, CO) ; Koudele;
Larry J.; (Erie, CO) ; Nowell; Shane; (Boise,
ID) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Micron Technology, Inc. |
Boise |
ID |
US |
|
|
Appl. No.: |
17/008225 |
Filed: |
August 31, 2020 |
International
Class: |
G11C 16/10 20060101
G11C016/10; G11C 16/08 20060101 G11C016/08; G06F 12/06 20060101
G06F012/06 |
Claims
1. A system comprising: a memory device; and a processing device,
operatively coupled to the memory device, to perform operations
comprising: programming one or more blocks at the memory device,
wherein the one or more blocks are associated with a block family
and with one or more dice of a die group comprising a plurality of
dice; determining, based on a subset of dice of the die group, a
voltage offset bin associated with the plurality of dice in the die
group and with the block family; and appending, to metadata
associated with the memory device, a record associating the die
group and the block family with the voltage offset bin.
2. The system of claim 1, wherein to determine the voltage offset
bin associated with the die group, the processing device is further
to perform operations comprising: determining a read threshold
voltage offset for the subset of dice of the die group; and
identifying, based on the read threshold voltage offset for the
subset of dice of the die group, the voltage offset bin from an
offset table of the metadata.
3. The system of claim 1, wherein determining the voltage offset
bin associated with the die group is performed responsive to
detecting a first triggering event.
4. The system of claim 3, wherein the first triggering event
corresponds to one of: a counter meeting or exceeding a threshold
value or a power down event that clears the counter.
5. The system of claim 1, wherein the processing device is further
to perform operations comprising: responsive to detecting a second
triggering event, determining whether a composition of dice of the
die group is to be modified; and responsive to determining that the
die group is to be modified, changing the composition of the dice
of the die group from a first plurality of dice to a second
plurality of dice.
6. The system of claim 5, wherein detecting the second triggering
event further comprises: determining that a number of program-erase
(PE) cycles of the memory device meets or exceeds a threshold
number of PE cycles.
7. The system of claim 5, wherein to determine whether the
composition of dice of the die group is to be modified, the
processing device is to perform operations comprising: determining
values of a data state metric that characterize a temporal voltage
shift for each of the first plurality of dice of the die group;
determining, based on the values of the data state metric, that the
temporal voltage shift of one or more of the first plurality of
dice of the die group is outside a range; and responsive to
determining that the temporal voltage shift of the one or more of
the first plurality of dice of the die group is outside the range,
removing the one or more of the first plurality of dice from the
die group.
8. The system of claim 7, wherein to determine whether the
composition of dice of the die group is to be modified, the
processing device is further to perform operations comprising:
determining other values of the data state metric that characterize
a temporal voltage shift for each of a third plurality of dice that
are not part of the die group; determining, based on the other
values of the data state metric, that the temporal voltage shift of
one or more of the third plurality of dice is within the range; and
responsive to determining that the temporal voltage shift of the
one or more of the third plurality of dice is within the range,
adding the one or more of the third plurality of dice to the die
group.
9. The system of claim 7, wherein to determine whether the
composition of dice of the die group is to be modified, the
processing device is further to perform operations comprising:
determining operational temperatures of the first plurality of dice
of the die group; determining that the operation temperatures for
one or more of the first plurality of dice of the die group is
outside a temperature range; and responsive to determining that the
operation temperatures for the one or more of the first plurality
of dice of the die group is outside the temperature range, removing
the one or more of the first plurality of dice from the die
group.
10. A method comprising: determining values of a data state metric
that characterizes a temporal voltage shift for each of a plurality
of dice of a memory device; determining, based on the values of the
data state metric, that the temporal voltage shift of a first
subset of the plurality of dice is within a first range; and
assigning, by a processing device, the first subset of dice to a
first die group, wherein the first die group corresponds to an
offset table of metadata that identifies read threshold voltage
offsets for the first die group.
11. The method of claim 10, further comprising: determining, based
on the values of the data state metric, that the temporal voltage
shift of a second subset of the plurality of dice is within a
second range; and assigning the second subset of die to a second
die group, wherein the first die group and the second die group
correspond to different offset tables that identify different read
threshold voltage offsets.
12. The method of claim 10, further comprising: determining
operational temperatures of the first subset of dice of the first
die group; determining that the operation temperatures for one or
more of the first subset of dice of the first die group is within a
first temperature range; and removing the one or more of the first
subset of dice from the first die group.
13. The method of claim 12, further comprising: assigning the one
or more dice removed from the first subset of dice to a third die
group.
14. The method of claim 12, further comprising: determining that
the operational temperatures for remaining dice of the first subset
of dice of the first die group are within a second temperature
range, wherein the remaining dice remain assigned to the first die
group.
15. A non-transitory computer-readable medium comprising
instruction that, responsive to execution by a processing device,
cause the processing device to perform operations comprising:
programming one or more blocks at a memory device, wherein the one
or more blocks are associated with a block family and with one or
more dice of a die group comprising a plurality of dice;
determining, based on a subset of dice of the die group, a voltage
offset bin associated with the plurality of dice in the die group
and with the block family; and appending, to metadata associated
with the memory device, a record associating the die group and the
block family with the voltage offset bin.
16. The non-transitory computer-readable medium of claim 15,
wherein to determine the voltage offset bin associated with the die
group, the operations further comprising: determining a read
threshold voltage offset for the subset of dice of the die group;
and identifying, based on the read threshold voltage offset for the
subset of dice of the die group, the voltage offset bin from an
offset table of the metadata.
17. The non-transitory computer-readable medium of claim 15, the
operations further comprising: responsive to detecting a triggering
event, determining whether a composition of dice of the die group
is to be modified; and responsive to determining that the die group
is to be modified, changing the composition of the dice of the die
group from a first plurality of dice to a second plurality of
dice.
18. The non-transitory computer-readable medium of claim 17,
wherein to determine whether the composition of dice of the die
group is to be modified, the operations further comprising:
determining values of a data state metric that characterize a
temporal voltage shift for each of the first plurality of dice of
the die group; determining, based on the values of the data state
metric, that the temporal voltage shift of one or more of the first
plurality of dice of the die group is outside a range; and
responsive to determining that the temporal voltage shift of the
one or more of the first plurality of dice of the die group is
outside the range, removing the one or more of the first plurality
of dice from the die group.
19. The non-transitory computer-readable medium of claim 18,
wherein to determine whether the composition of dice of the die
group is to be modified, the operations further comprising:
determining operational temperatures of the first plurality of dice
of the die group; determining that the operation temperatures for
one or more of the first plurality of dice of the die group is
outside a temperature range; and responsive to determining that the
operation temperatures for the one or more of the first plurality
of dice of the die group is outside the temperature range; removing
the one or more of the first plurality of dice from the die
group.
20. The non-transitory computer-readable medium of claim 18,
wherein to determine whether the composition of dice of the die
group is to be modified, the operations further comprising:
determining other values of the data state metric that characterize
a temporal voltage shift for each of a third plurality of dice that
are not part of the die group; determining, based on the other
values of the data state metric, that the temporal voltage shift of
one or more of the third plurality of dice is within the range; and
responsive to determining that the temporal voltage shift of the
one or more of the third plurality of dice is within the range,
adding the one or more of the third plurality of dice to the die
group.
Description
TECHNICAL FIELD
[0001] Embodiments of the disclosure are generally related to
memory sub-systems, and more specifically, are related to voltage
offset bin selection by die group for memory devices.
BACKGROUND
[0002] A memory sub-system can include one or more memory devices
that store data. The memory devices can be, for example,
non-volatile memory devices and volatile memory devices. In
general, a host system can utilize a memory sub-system to store
data at the memory devices and to retrieve data from the memory
devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The disclosure will be understood more fully from the
detailed description given below and from the accompanying drawings
of some embodiments of the disclosure.
[0004] FIG. 1 illustrates an example computing system that includes
a memory sub-system, in accordance with some embodiments of the
disclosure.
[0005] FIG. 2 illustrates an example computing system that includes
a memory sub-system, in accordance with some embodiments of the
disclosure.
[0006] FIG. 3 schematically illustrates example metadata maintained
by the memory sub-system controller for associating die groups with
block families, in accordance with embodiments of the
disclosure.
[0007] FIG. 4 illustrates the temporal voltage shift caused at
least in part by the slow charge loss exhibited by triple-level
memory cells, in accordance with embodiments of the disclosure.
[0008] FIG. 5 illustrates a graph representing time voltage shift
and a set of predefined threshold voltage offset bins, in
accordance with embodiments of the disclosure.
[0009] FIG. 6 is a flow diagram of an example method of die group
management implemented by a memory sub-system controller operating,
in accordance with some embodiments of the disclosure.
[0010] FIG. 7 is a flow diagram of an example method of determining
die groups, in accordance with some embodiments of the
disclosure.
[0011] FIG. 8 is a block diagram of an example computer system in
which embodiments of the disclosure can operate.
DETAILED DESCRIPTION
[0012] Embodiments of the disclosure are directed to voltage offset
bin selection by die group for memory devices. A memory sub-system
can be a storage device, a memory module, or a hybrid of a storage
device and memory module. Examples of storage devices and memory
modules are described below in conjunction with FIG. 1. In general,
a host system can utilize a memory sub-system that includes one or
more components, such as memory devices that store data. The host
system can provide data to be stored at the memory sub-system and
can request data to be retrieved from the memory sub-system.
[0013] "Block" herein shall refer to a set of contiguous or
non-contiguous memory pages. An example of "block" is "erasable
block," which is the minimal erasable unit of memory, while "page"
is a minimal writable unit of memory. Each page includes of a set
of memory cells ("cells"). A memory cell is an electronic circuit
that stores information.
[0014] A memory sub-system can utilize one or more memory devices,
including any combination of the different types of non-volatile
memory devices and/or volatile memory devices, to store the data
provided by the host system. In some embodiments, non-volatile
memory devices can be provided by not-and (NAND) type flash memory
devices. Other examples of non-volatile memory devices are
described below in conjunction with FIG. 1. A non-volatile memory
device is one or more packages of one or more dice. Each die can
consist of one or more planes. Planes can be groups into logic
units (LUN). For some types of non-volatile memory devices (e.g.,
NAND devices), each plane includes a set of erasable blocks.
[0015] Data operations can be performed by the memory sub-system.
The data operations can be host-initiated operations. For example,
the host system can initiate a data operation (e.g., write, read,
erase, etc.) on a memory sub-system. The host system can send
access requests (e.g., write command, read command) to the memory
sub-system, such as to store data on a memory device at the memory
sub-system and to read data from the memory device on the memory
sub-system. The data to be read or written, as specified by a host
request, is hereinafter referred to as "host data". A host request
can include logical address information (e.g., logical block
address (LBA), namespace) for the host data, which is the location
the host system associates with the host data. The logical address
information (e.g., LBA, namespace) can be part of metadata for the
host data. Metadata can also include error handling data (e.g., ECC
codeword, parity code), data version (e.g. used to distinguish age
of data written), valid bitmap (which LBAs or logical transfer
units contain valid data), etc.
[0016] A memory device includes multiple memory cells, each of
which can store, depending on the memory cell type, one or more
bits of information. A memory cell can be programmed (written to)
by applying a certain voltage to the memory cell, which results in
an electric charge being held by the memory cell, thus allowing
modulation of the voltage distributions produced by the memory
cell. Moreover, precisely controlling the amount of the electric
charge held by the memory cell allows to establish multiple
threshold voltage levels corresponding to different logical levels,
thus effectively allowing a single memory cell to store multiple
bits of information: a memory cell operated with 2.sup.n different
threshold voltage levels is capable of storing n bits of
information. "Threshold voltage" herein shall refer to the voltage
level at which a memory cell turns on or is conductive and that
defines a boundary between two neighboring voltage distributions
corresponding to two logical levels. Thus, the read operation can
be performed by comparing the measured voltage exhibited by the
memory cell to one or more reference voltage levels in order to
distinguish between two logical levels for single-level cells and
between multiple logical levels for multi-level cells.
[0017] Due to the phenomenon known as slow charge loss, the
threshold voltage of a memory cell changes in time as the electric
charge of the cell is degrading, which is referred to as "temporal
voltage shift" (since the degrading electric charge causes the
voltage distributions to shift along the voltage axis towards lower
voltage levels). The threshold voltage is changing rapidly at first
(immediately after the memory cell was programmed), and then slows
down in an approximately logarithmic linear fashion with respect to
the time elapsed since the cell programming event. Accordingly,
failure to mitigate the temporal voltage shift caused by the slow
charge loss can result in the increased bit error rate in read
operations.
[0018] However, various common implementations either fail to
adequately address the temporal voltage shift or employ inefficient
strategies resulting in high bit error rates and/or exhibiting
other shortcomings (e.g., computational or storage inefficiencies
in implementing the different strategies). Aspects of the
disclosure address the above-noted and other deficiencies by
implementing a memory sub-system that employs die-group-based error
avoidance strategies, thus significantly improving the bit error
rate exhibited by the memory sub-system.
[0019] In accordance with embodiments of the disclosure, the
temporal voltage shift is selectively tracked for programmed blocks
grouped by block families using representative die of a die group,
and appropriate voltage offsets, which are based on block
affiliation with die group, are applied to the base read levels in
order to perform read operations. "Die group" herein shall refer to
one or more die that share one or more characteristics, such
temporal voltage shift characteristics or operational temperature
characteristics.
[0020] "Block family" herein shall refer to a possibly
noncontiguous set of memory cells (which can reside in one or more
full and/or partial blocks, the latter referred to as "partitions"
herein) that have been programmed within a specified time window
and a specified temperature window, and thus are expected to
exhibit similar or correlated changes in their respective data
state metrics. A block family may be made with any granularity,
containing only whole codewords, whole pages, whole super pages, or
whole superblocks, or any combination of these.
[0021] "Data state metric" herein shall refer to a quantity that is
measured or inferred from the state of data stored on a memory
device. Specifically, the data state metrics may reflect the state
of the temporal voltage shift, the degree of read disturb, and/or
other measurable functions of the data state. A composite data
state metric is a function (e.g., a weighted sum) of a set of
component state metrics.
[0022] Since the time elapsed after programming and temperature are
the main factors affecting the temporal voltage shift, all die
within a single die group are presumed to exhibit similar
distributions of threshold voltages in memory cells, and thus would
require the same voltage offsets to be applied to the base read
levels for read operations. "Base read level" herein shall refer to
the initial threshold voltage level exhibited by the memory cell
immediately after programming. In some implementations, base read
levels can be stored in the metadata of the memory device.
[0023] In some embodiments, dice that are to be included in a
particular die group can be determined. The dice in a particular
die group can share one or more characteristics, such as temporal
voltage shift characteristics or operational temperature
characteristics. For example, the dice in a die group can have
similar values of a data state metric indicative of temporal
voltage shift and experience operational temperatures on average of
70 to 75 degrees Celsius. The temporal voltage shift
characteristics of a die can be determined using values of a data
state metric. The operational temperature characteristics can be
determined using operational temperature measurements indicative of
the operational temperature of one or more dice of a memory device
or memory sub-system. In some embodiments, subsequent to forming
the die groups a calibration process to associate each die group
with a predefined read threshold voltage offset bin can be
performed from time to time. To perform a calibration process, the
temporal voltage shift characteristics can be determined for one or
more representative dice of a die group (e.g., rather than all the
dice of the die group). The determined temporal voltage shift
characteristics of the representative dice of the die group can be
used to identify the predefined read threshold voltage offset bin
for the die group.
[0024] The memory sub-system controller (or host system) can
determine values of a data state metric that characterizes a
temporal voltage shift for each of the dice of a memory device or
memory sub-system. The memory sub-system controller (or host
system) can determine, based on the values of the data state metric
that the temporal voltage shift of an initial subset of the dice is
within a range. The memory sub-system controller (or host system)
can assign the initial subset of dice to an initial die group. The
initial die group can correspond to an offset table of metadata
that identifies read threshold voltage offsets for the initial die
group.
[0025] In some embodiments, the memory sub-system controller (or
host system) can determine operational temperatures of the initial
subset of dice of the initial die group. Memory sub-system
controller can determine that the operational temperatures for one
or more of the initial subset of dice of the initial die group are
within a temperature range. The one or more of the initial subset
of dice from the initial die group can be removed and assigned to a
new die group.
[0026] In some embodiments, the memory sub-system controller can
periodically perform a calibration process in order to associate
each die group with a predefined read threshold voltage offset bin,
which is in turn associated with the voltage offset to be applied
for read operations. "Threshold voltage offset bin" herein can
refer to a set of read level offsets that are applied to a set of
data. The associations of blocks with block families and block
families and die groups with threshold voltage offset bins can be
stored in respective metadata tables maintained by the memory
sub-system controller. To perform the calibration process, the
memory sub-system controller can measure the threshold voltage of
one or more representative dice of the die group, rather than all
the dice of the die group, because the dice of the die group
exhibit similar temporal voltage shift characteristics or
experience similar operation temperatures, and as such the behavior
of the voltage distributions over time for some of the dice of the
die group can accurately represent the voltage distribution
behavior over time for all the dice of a die group. Moreover, one
or more metadata tables (e.g., family table) can also be reduced in
size because the metadata of die groups can be less than metadata
for each die of a memory sub-system or memory device.
[0027] Therefore, advantages of the systems and methods implemented
in accordance with some embodiments of the disclosure include, but
are not limited to, improving the bit error rate in read operations
by maintaining metadata tracking die groups that are presumed to
exhibit similar voltage distributions and selectively performing
calibration operations for die groups using one or more
representative dice of dice of a die group, as described in more
detail herein below.
[0028] FIG. 1 illustrates an example computing system 100 that
includes a memory sub-system 110 in accordance with some
embodiments of the disclosure. The memory sub-system 110 can
include media, such as one or more volatile memory devices (e.g.,
memory device 140), one or more non-volatile memory devices (e.g.,
memory device 130), or a combination of such.
[0029] A memory sub-system 110 can be a storage device, a memory
module, or a hybrid of a storage device and memory module. Examples
of a storage device include a solid-state drive (SSD), a flash
drive, a universal serial bus (USB) flash drive, an embedded
Multi-Media Controller (eMMC) drive, a Universal Flash Storage
(UFS) drive, a secure digital (SD) card, and a hard disk drive
(HDD). Examples of memory modules include a dual in-line memory
module (DIMM), a small outline DIMM (SO-DIMM), and various types of
non-volatile dual in-line memory module (NVDIMM).
[0030] The computing system 100 can be a computing device such as a
desktop computer, laptop computer, network server, mobile device, a
vehicle (e.g., airplane, drone, train, automobile, or other
conveyance), Internet of Things (IoT) enabled device, embedded
computer (e.g., one included in a vehicle, industrial equipment, or
a networked commercial device), or such computing device that
includes memory and a processing device (e.g., a processor).
[0031] The computing system 100 can include a host system 120 that
is coupled to one or more memory sub-systems 110. In some
embodiments, the host system 120 is coupled to different types of
memory sub-systems 110. FIG. 1 illustrates one example of a host
system 120 coupled to one memory sub-system 110. As used herein,
"coupled to" or "coupled with" generally refers to a connection
between components, which can be an indirect communicative
connection or direct communicative connection (e.g., without
intervening components), whether wired or wireless, including
connections such as electrical, optical, magnetic, etc.
[0032] The host system 120 can include a processor chipset and a
software stack executed by the processor chipset. The processor
chipset can include one or more cores, one or more caches, a memory
controller (e.g., NVDIMM controller), and a storage protocol
controller (e.g., PCIe controller, SATA controller). The host
system 120 uses the memory sub-system 110, for example, to write
data to the memory sub-system 110 and read data from the memory
sub-system 110.
[0033] The host system 120 can be coupled to the memory sub-system
110 via a physical host interface. Examples of a physical host
interface include, but are not limited to, a serial advanced
technology attachment (SATA) interface, a peripheral component
interconnect express (PCIe) interface, universal serial bus (USB)
interface, Fibre Channel, Serial Attached SCSI (SAS), a double data
rate (DDR) memory bus, Small Computer System Interface (SCSI), a
dual in-line memory module (DIMM) interface (e.g., DIMM socket
interface that supports Double Data Rate (DDR)), Open NAND Flash
Interface (ONFI), Double Data Rate (DDR), Low Power Double Data
Rate (LPDDR), etc. The physical host interface can be used to
transmit data between the host system 120 and the memory sub-system
110. The host system 120 can further utilize an NVM Express (NVMe)
interface to access components (e.g., memory devices 130) when the
memory sub-system 110 is coupled with the host system 120 by the
PCIe interface. The physical host interface can provide an
interface for passing control, address, data, and other signals
between the memory sub-system 110 and the host system 120. FIG. 1
illustrates a memory sub-system 110 as an example. In general, the
host system 120 can access multiple memory sub-systems via a same
communication connection, multiple separate communication
connections, and/or a combination of communication connections.
[0034] The memory devices 130,140 can include any combination of
the different types of non-volatile memory devices and/or volatile
memory devices. The volatile memory devices (e.g., memory device
140) can be, but are not limited to, random access memory (RAM),
such as dynamic random access memory (DRAM) and synchronous dynamic
random access memory (SDRAM).
[0035] Some examples of non-volatile memory devices (e.g., memory
device 130) include negative-and (NAND) type flash memory and
write-in-place memory, such as a three-dimensional cross-point ("3D
cross-point") memory device, which is a cross-point array of
non-volatile memory cells. A cross-point array of non-volatile
memory can perform bit storage based on a change of bulk
resistance, in conjunction with a stackable cross-gridded data
access array. Additionally, in contrast to many flash-based
memories, cross-point non-volatile memory can perform a write
in-place operation, where a non-volatile memory cell can be
programmed without the non-volatile memory cell being previously
erased. NAND type flash memory includes, for example,
two-dimensional NAND (2D NAND) and three-dimensional NAND (3D
NAND).
[0036] Each of the memory devices 130 can include one or more
arrays of memory cells. One type of memory cell, for example,
single level cells (SLC) can store one bit per cell. Other types of
memory cells, such as multi-level cells (MLCs), triple level cells
(TLCs), and quad-level cells (QLCs), can store multiple bits per
cell. In some embodiments, each of the memory devices 130 can
include one or more arrays of memory cells such as SLCs, MLCs,
TLCs, QLCs, or any combination of such. In some embodiments, a
particular memory device can include an SLC portion, and an MLC
portion, a TLC portion, or a QLC portion of memory cells. The
memory cells of the memory devices 130 can be grouped as pages that
can refer to a logical unit of the memory device used to store
data. With some types of memory (e.g., NAND), pages can be grouped
to form blocks.
[0037] Although non-volatile memory devices such as 3D cross-point
array of non-volatile memory cells and NAND type memory (e.g., 2D
NAND, 3D NAND) are described, the memory device 130 can be based on
any other type of non-volatile memory, such as read-only memory
(ROM), phase change memory (PCM), self-selecting memory, other
chalcogenide based memories, ferroelectric transistor random-access
memory (FeTRAM), ferroelectric random access memory (FeRAM),
magneto random access memory (MRAM), Spin Transfer Torque
(STT)-MRAM, conductive bridging RAM (CBRAM), resistive random
access memory (RRAM), oxide based RRAM (OxRAM), negative-or (NOR)
flash memory, and electrically erasable programmable read-only
memory (EEPROM).
[0038] A memory sub-system controller 115 (or controller 115 for
simplicity) can communicate with the memory devices 130 to perform
operations such as reading data, writing data, or erasing data at
the memory devices 130 and other such operations. The memory
sub-system controller 115 can include hardware such as one or more
integrated circuits and/or discrete components, a buffer memory, or
a combination thereof. The hardware can include digital circuitry
with dedicated (i.e., hard-coded) logic to perform the operations
described herein. The memory sub-system controller 115 can be a
microcontroller, special purpose logic circuitry (e.g., a field
programmable gate array (FPGA), an application specific integrated
circuit (ASIC), etc.), or other suitable processor.
[0039] The memory sub-system controller 115 can include a processor
117 (e.g., processing device) configured to execute instructions
stored in a local memory 119. In the illustrated example, the local
memory 119 of the memory sub-system controller 115 includes an
embedded memory configured to store instructions for performing
various processes, operations, logic flows, and routines that
control operation of the memory sub-system 110, including handling
communications between the memory sub-system 110 and the host
system 120.
[0040] In some embodiments, the local memory 119 can include memory
registers storing memory pointers, fetched data, etc. The local
memory 119 can also include read-only memory (ROM) for storing
micro-code. While the example memory sub-system 110 in FIG. 1 has
been illustrated as including the controller 115, in another
embodiment of the disclosure, a memory sub-system 110 does not
include a controller 115, and can instead rely upon external
control (e.g., provided by an external host, or by a processor or
controller separate from the memory sub-system).
[0041] In general, the memory sub-system controller 115 can receive
commands or operations from the host system 120 and can convert the
commands or operations into instructions or appropriate commands to
achieve the desired access to the memory devices 130. The memory
sub-system controller 115 can be responsible for other operations
such as wear leveling operations, garbage collection operations,
error detection and error-correcting code (ECC) operations,
encryption operations, caching operations, and address translations
between a logical address (e.g., logical block address (LBA),
namespace) and a physical address (e.g., physical block address)
that are associated with the memory devices 130. The memory
sub-system controller 115 can further include host interface
circuitry to communicate with the host system 120 via the physical
host interface. The host interface circuitry can convert the
commands received from the host system into command instructions to
access the memory devices 130 as well as convert responses
associated with the memory devices 130 into information for the
host system 120.
[0042] In some implementations, memory sub-system 110 can use a
striping scheme, according to which every the data payload (e.g.,
user data) utilizes multiple dies of the memory devices 130 (e.g.,
NAND type flash memory devices), such that the payload is
distributed through a subset of dies, while the remaining one or
more dies are used to store the error correction information (e.g.,
parity bits). Accordingly, a set of blocks distributed across a set
of dies of a memory device using a striping scheme is referred
herein to as a "superblock."
[0043] The memory sub-system 110 can also include additional
circuitry or components that are not illustrated. In some
embodiments, the memory sub-system 110 can include a cache or
buffer (e.g., DRAM) and address circuitry (e.g., a row decoder and
a column decoder) that can receive an address from the controller
115 and decode the address to access the memory devices 130.
[0044] In some embodiments, the memory devices 130 include local
media controllers 135 that operate in conjunction with memory
sub-system controller 115 to execute operations on one or more
memory cells of the memory devices 130. An external controller
(e.g., memory sub-system controller 115) can externally manage the
memory device 130 (e.g., perform media management operations on the
memory device 130). In some embodiments, a memory device 130 is a
managed memory device, which is a raw memory device combined with a
local controller (e.g., local controller 135) for media management
within the same memory device package. An example of a managed
memory device is a managed NAND (MNAND) device.
[0045] The memory sub-system 110 includes a die group manager
component 113 that can be used to implement the die group error
avoidance strategies, in accordance with embodiments of the
disclosure. In some embodiments, the controller 115 includes at
least a portion of the die group manager component 113. For
example, the controller 115 can include a processor 117 (processing
device) configured to execute instructions stored in local memory
119 for performing the operations described herein. In some
embodiments, the die group manager component 113 is part of the
host system 120, an application, or an operating system. The die
group manager component 113 can manage die groups associated with
the memory devices 130, as described in more detail herein
below.
[0046] FIG. 2 illustrates an example computing system that includes
a memory sub-system, in accordance with some embodiments of the
disclosure. The description of FIG. 1 and the elements therein
apply to FIG. 2, unless otherwise described. Memory sub-system 110
illustrates family table 220 stored at local memory 119 of the
memory sub-system controller 115 and offset table 230 and die group
table 210 stored at memory device 130. Family table 220, offset
table 230, and die group table 210 are further described with
respect to FIG. 3.
[0047] In some embodiments, the composition of dice in one or more
die groups can be determined. Grouping one or more dice to create a
die group can be based on one or more of temporal voltage shift
characteristics of the dice of the memory device 130 or memory
sub-system 110 or the operational temperature characteristics of
the dice of the memory device 130 or memory sub-system 110. In some
embodiments, values of the data state metric can be indicative of
the temporal voltage shift characteristics of a die. For example,
the dice of a die group can have similar temporal voltage shift
characteristics and operational temperature characteristics.
"Operational temperature" or "operational temperature
characteristics" herein can refer to the estimated temperature of a
die during the operation of the memory device 130 or memory
sub-system 110. In some embodiments, the operational temperature
can be an estimate of the temperature of a die at a point in time
or one or more windows of time (e.g., average temperature).
[0048] In some embodiments, to create the die groups (e.g., to
determine the composition of dice in each die group), die group
manager component 113 can determine values of a data state metric
that characterizes a temporal voltage shift for each of the dice of
a memory device 130 or memory sub-system 110. For example, the
threshold voltages of a die can measured over time to determine a
function representing the threshold voltage shift over time for a
particular die. Examples of determining values of a data state
metric that characterizes a temporal voltage shift are further
described with respect to FIG. 5.
[0049] In some embodiments, die group manager component 113 can
determine that the temporal voltage shift of a subset of the dice
of the memory device 130 or memory sub-system 110 is within a range
based on the values of the data state metric. In some embodiments,
the values of the data state metric can be determined to be within
a range. In some embodiments, the values of the data state metric
can be used to derive values indicative of temporal voltage shift
and the values indicative of the temporal voltage shift can be
determined to be within a range. For example, the slopes of
functions representing the threshold voltages over time for
different die can be identified. A subset of dice that have
threshold voltage slopes that are within a range (e.g., similar
threshold voltage slopes) can be assigned to an initial die group.
Another subset of dice that have threshold slopes that are within
another range can be assigned to another die group, and so
forth.
[0050] In some embodiments, the die groups can be further refined
based on operational temperature characteristics. Die group manager
component 113 can determine the operational temperature
characteristics of dice of a die group. For example, a
pre-characterization can be performed to characterize the
temperature profile of one or more dice or packages of the memory
sub-system. In another example, on-board temperature sensors at the
board level, package level, or die level, for example, can be used
to estimate or measure the temperature of the dice of the memory
sub-system 110 or memory device 130 during operation.
[0051] In some embodiments, die group manager component 113 can
determine that the operational temperature characteristics of one
or more dice of the initial die group is within an initial
temperature range. The one or more dice that are within the initial
temperature range are removed from the initial die group and
assigned to a new die group (e.g., third die group). In some
embodiments, die group manager component 113 determines that the
operational temperature characteristics for the remaining dice of
the initial die group are within a different temperature range and
remain assigned to the initial die group.
[0052] For example, the initial die group can include 4 dice (die 1
through die 4) that are physically spread out across the memory
sub-system 110. Die 1 and die 2 have an average operating
temperature of 80 degrees Celsius over a window of time, and die 3
and die 4 have an average operating temperature of 122 and 125
degrees Celsius over the window of time. Die 1 and die 2 have
operational temperatures that fall within an initial temperature
range (e.g., 75-85 degrees Celsius) and are assigned to a new die
group. Die 3 and die 4 have operational temperatures that fall
within a different temperature range (e.g., 120-130 degrees
Celsius) over the window of time and remain assigned to the initial
die group.
[0053] In some embodiments, for each die group one or more records
can be created in metadata, and specifically in the die group table
210 that records an association between the one or more dice and
the die group to which the one or more dice area assigned. In some
embodiments, one or more offset tables 230 can be associated the
die groups. In some embodiments, each of the die groups can be
associated with a different offset table 230. Having multiple
offset tables 230 that are each associated with a particular die
group can allow the die groups to have read threshold bin offsets
that are unique to the die group and based on the characteristics
(e.g., temperature voltage shift characteristics and operational
temperature characteristics) of the dice of a die group. Offset
table 230 and die group table 210 are further described below with
respect to FIG. 3.
[0054] In some embodiments, the die groups can be determined during
a pre-characterization operation. In some embodiments, the
pre-characterization operation (e.g., prior to releasing the memory
sub-system 110 into the field) can be performed by die group
manager component 113 executing at host system 120 or memory
sub-system 110. In some embodiments, the die groups can be
determined (or re-determined) based on characterization on board
the memory sub-system 110. In some embodiments, the
characterization on board the memory sub-system 110 can be
performed dynamically (e.g., in the field), such as responsive to
the satisfaction of a triggering event.
[0055] In some embodiments, responsive to determining a triggering
event, die group manager component 113 determines whether a
composition of dice of the die group is to be modified (or new die
group created). In some embodiments the triggering event can
correspond to a number of program-erase (PE) cycles of the memory
device 130 (or memory sub-system 110) meeting or exceeding a
threshold number of PE cycles. For example, during on-board
characterization die group manager component 113 can determine that
composition of dice of one or more die groups is to be modified or
that one or more die groups are to be created (or removed)
responsive to the number program-erase (PE) cycles performed by the
memory sub-system 110 (or memory device 130) meeting or exceeding a
1000 PE cycles. One or more of the temporal voltage shift
characteristics or operational temperature characteristics for the
memory device 130 or memory sub-system 110 can be measured, as
described above. The temporal voltage shift characteristics or
operational temperature characteristics of dice of a memory
sub-system 110 or memory device 130 can change over time due to
wear. New die groups can be created or the composition of dice in
existing die groups can be modified based on new measurements
indicative of temporal voltage shift characteristics or operational
temperature characteristics such that dice of a particular die
group have similar temporal voltage shift characteristics or
operational temperature characteristics at any point in time.
[0056] In some embodiments, die group manager component 113 can
program one or more blocks at a memory device 130 or memory
sub-system 110. The one or more blocks can be associated with one
or more block families. The one or more blocks can be part of one
or more dice of the memory device 130 or memory sub-system 110. The
one or more dice can be part of a single die group or one or more
die groups.
[0057] In some embodiments, a newly created block family can be
associated with bin 0. Then, the memory sub-system controller 115
can periodically perform a calibration process in order to
associate each die group with one of the predefined read threshold
voltage offset bins (bins 0-9 in the illustrative example of FIG.
5), which are in turn associated with the read voltage offset to be
applied for read operations. The associations of blocks with block
families and block families and die groups with read threshold
voltage offset bins can be stored in respective metadata tables
maintained by the memory sub-system controller 115.
[0058] In some embodiments, die group manager component 113 can
periodically perform a calibration process to determine a current
read threshold voltage offset bin associated with the die group
based on one or more dice that are representative of dice of the
die group. Based on the calibration process, the memory sub-system
controller 115 associates each die group with a read threshold
voltage offset bin, which defines a set of read threshold voltage
offsets to be applied to the base voltage read level in order to
perform read operations. In some embodiments, the calibration
process involves identifying one or more representative dice of the
die group. For example, one or more dice of the die group that are
representative dice of a die group can be randomly, pseudo-randomly
selected, selected from an order, and so forth. In some
embodiments, the die group includes multiple dice and the one or
more representative dice are a subset of the dice of the die group.
In some embodiments, the calibration process further involves
performing, with respect to the selected representative dice of the
one or more die groups, read operations utilizing different read
threshold voltage offsets, in order to determine the read threshold
voltage offset that minimizes the error rate of the read operation.
In some embodiments, the new read threshold offset bin can be
identified using the metadata, and specifically the offset table
230, as the bin having a range of read threshold voltage offsets
that includes read threshold voltage offset that minimizes the
error rate of the read operation. Each time the calibration
processes selects a new bin (e.g., new read threshold voltage
offset bin), the metadata, and specifically family table 220, can
be updated or appended to reflect the change. For example, the
family table 220 metadata can be appended to indicate the new read
threshold voltage offset bin is associated with the die group.
[0059] In some embodiments, the calibration process (e.g.,
determining whether a new read threshold offset bin is to be
associated with a die group) can be performed responsive to a
triggering event corresponding to a counter. For example, each time
a block family is programmed a counter can be initialized. The
values of the counter can indicate the amount of time data that has
elapsed since the data was last programmed to the respective block
family. In some embodiments, a calibration process can be performed
responsive to determining that the counter meets or exceeds a
threshold value. For example, when the counter indicates that 10
hours has elapsed since the block family was last programmed, a
calibration process can be initiated. In some embodiments, the
triggering event corresponding to the counter can be a power down
event that clears the counter. A power down event can include any
event that clears the counter such the counter no longer can be
used to accurately estimate the time that has elapsed since the
corresponding block family was last programmed. Examples of a power
down event can include a full shut down of the power system or a
sleep power cycle that prevents the counter from performing a
counting function.
[0060] FIG. 3 schematically illustrates example metadata maintained
by the memory sub-system controller for associating die groups with
block families, in accordance with embodiments of the disclosure.
As schematically illustrated by FIG. 3, the memory sub-system
controller can maintain the die group table 310, the family table
320, and the offset table 330. Die group table 310, the family
table 320, and the offset table 330 can be similar to die group
table 210, family table 220, and offset table 230, respectively, as
described with respect to FIG. 2.
[0061] Each record of the die group table 310 specifies the die
associated with the specified die group. For example, die 1 through
die 5 of the memory sub-system are associated with die group A and
die 62 through N are associated with die group N. In some
embodiments, the die of a die group can change during the life of a
memory device or memory sub-system. As such, the die group table
310 can be updated accordingly.
[0062] In some embodiments, superblock table (not shown) specifies
the block family associated with the specified superblock and
partition combination.
[0063] The family table 320 is indexed by the block family number,
such that each record of the family table 320 specifies, for the
block family referenced by the index of the record, a set of read
threshold voltage offset bins associated with respective die
groups. In other words, each record of the family table 320
includes a vector, each element of which specifies the read
threshold voltage offset bin associated with the die group
referenced by the index of the vector element. The read threshold
voltage offset bins to be associated with the die groups can be
determined by the calibration process, as described in more detail
herein above. In some embodiments, the family table 320 can be
indexed by the block number, such that each record of the family
table 320 specifies, for the block family referenced by the index
of the record, a set of read threshold voltage offset bins
associated with respective die groups. The memory sub-system
controller 115 can use a firmware data structure, such as die group
table 310, to determine which die are associated with which die
groups.
[0064] Finally, the offset table 330 is indexed by the read
threshold voltage offset bins. Each record of the offset table 330
specifies a set of read threshold voltage offsets (e.g., for
programming distribution L1 through programming distribution L7)
associated with each read threshold voltage offset bin. In some
embodiments, one or more die groups can have different offset
tables. For example, each die group can have an offset table that
is specific to the particular die group. Having different offset
tables for different die groups allows for unique bin offsets for
each die group.
[0065] The metadata tables 310-330 can be stored at one or more
memory devices 130 of FIG. 1 or 2. In some implementations, at
least part of the metadata tables can be cached in the local memory
119 of the memory sub-system controller 115 of FIG. 1 or 2.
[0066] In operation, upon receiving a read command, the memory
sub-system controller determines the physical address corresponding
to the logical block address (LBA) specified by the read command.
Components of the physical address, such as the physical block
number and the die identifier (identified using the LBA), are
utilized for performing the metadata table walk: first, the
superblock table (not shown) is used to identify the block family
identifier corresponding to the physical block number; then, a die
group table 310 is used to determine which die group is associated
with a die associated with the physical block number; then, the
block family identifier is used as the index to the family table
320 in order to determine the read threshold voltage offset bin
associated with the block family and the die group; finally, the
identified read threshold voltage offset bin is used as the index
to the offset table 330 in order to determine the read threshold
voltage offset corresponding to the bin for each of the programing
distributions. The memory sub-system controller can then additively
apply the identified read threshold voltage offset to the base
voltage read level in order to perform the requested read
operation.
[0067] In the illustrative example of FIG. 3, the superblock table
maps partition 0 of the superblock 0 to block family 4, which is
utilized as the index to the family table 320 in order to determine
that die group A is mapped to bin 1. The latter value is used as
the index to the offset table 330 in order to determine the
threshold voltage offset values for bin 1. Die group table 310 can
be used to determine which die are in die group 1.
[0068] FIG. 4 illustrates the temporal voltage shift caused at
least in part by the slow charge loss exhibited by triple-level
memory cells, in accordance with embodiments of the disclosure.
While the illustrative example of FIG. 4 utilizes triple-level
cells, the same observations can be made and, accordingly, the same
remedial measures are applicable to single level cells and any
memory cells having multiple levels.
[0069] A memory cell can be programmed (written to) by applying a
certain voltage (e.g. program voltage) to the memory cell, which
results in an electric charge stored by the memory cell. Precisely
controlling the amount of the electric charge stored by the memory
cell allows a memory cell to have multiple threshold voltage levels
that correspond to different logical levels, thus effectively
allowing a single memory cell to store multiple bits of
information. A memory cell operated with 2.sup.n different
threshold voltage levels is capable of storing n bits of
information.
[0070] Each of chart 410 and 430 illustrate program voltage
distributions 420A-420N (also referred to as "program
distributions" or "voltage distributions" or "distributions"
herein) of memory cells programmed by a respective write level
(which can be assumed to be at the midpoint of the program
distribution) to encode a corresponding logical level ("000"
through "111" in case of a TLC). The program distributions 420A
through 420N can illustrate the range of threshold voltages (e.g.,
normal distribution of threshold voltages) for memory cells
programmed at respective write levels (e.g., program voltages). In
order to distinguish between adjacent program distributions
(corresponding to two different logical levels), the read threshold
voltage levels (shown by dashed vertical lines) are defined, such
that any measured voltage that falls below a read threshold level
is associated with one program distribution of the pair of adjacent
program distributions, while any measured voltage that is greater
than or equal to the read threshold level is associated with
another program distribution of the pair of neighboring
distributions.
[0071] As seen from comparing example charts 410 and 430, which
reflect the time after programming (TAP) of 0 (immediately after
programming) and the TAP of T hours (T=some positive number of
hours), respectively, the program distributions change over time
due primarily to slow charge loss. In order to reduce the read bit
error rate, the corresponding read threshold voltages are adjusted
to compensate for the shift in program distributions, which are
shown by dashed vertical lines. In various embodiments of the
disclosure, the temporal voltage shift is selectively tracked for
die groups based on measurements performed at one or more
representative dice of the die group. Based on the measurements
made on representative dice of a die group that characterize the
temporal voltage shift and operational temperature of the dice of
the die group, the read threshold voltage offsets used to read the
memory cells for the dice of the die group are updated and are
applied to the base read threshold levels to perform read
operations.
[0072] FIG. 5 illustrates a graph representing time voltage shift
and a set of predefined threshold voltage offset bins (bin 0 to bin
9), in accordance with embodiments of the disclosure.
[0073] The threshold voltage offset graph 500 can be subdivided
into multiple threshold voltage offset bins, such that each bin
corresponds to a predetermined range of threshold voltage offsets.
While the illustrative example of FIG. 5 defines ten bins, in other
embodiments, various other numbers of bins can be employed (e.g.,
64 bins). Based on a periodically performed calibration process,
the memory sub-system controller associates each die group with a
threshold voltage offset bin, which defines a set of threshold
voltage offsets to be applied to the base voltage read level in
order to perform read operations, as described in more detail
herein above.
[0074] As illustrated by graph 500, the time voltage shift is
represented by the change in (e.g., downward slope) the threshold
voltage offset over time. It can be noted that the y-axis
representing the threshold voltage offset is linear and the x-axis
representing time is logarithmic. The function of threshold voltage
offset over time can be represented by a logarithmic-linear
threshold voltage offset line as illustrated in graph 500.
[0075] The logarithmic-linear behavior of the threshold voltage
over time can be used to characterize the temporal voltage shift of
a die (or die group). For example, the threshold voltages of one or
more voltage distributions of a die can be measured at two
different times, for example at time 0 (0 minutes after program)
and time 1 (10 minutes after program). Using the two data points
(e.g., threshold voltage at time 0 and threshold voltage at time
1), the function of the threshold voltage over time can be
determined (e.g., function of a line using two points). In other
embodiments, more complex techniques such as curve fitting
techniques or linear extrapolation can be used to determine the
threshold voltage over time for a particular die. In some
embodiments, to determine die groups, die that have similar slopes
(e.g. similar curves) are grouped in the same die group. That is,
the die that have similar temperature voltage shift characteristics
can be grouped in the same die group.
[0076] The method 600 or 700 as described below can be performed by
processing logic that can include hardware (e.g., processing
device, circuitry, dedicated logic, programmable logic, microcode,
hardware of a device, integrated circuit, etc.), software (e.g.,
instructions run or executed on a processing device), or a
combination thereof. In some embodiments, method 600 or 700 is
performed by the die group manager component 113 of FIG. 1 or 2.
Although shown in a particular sequence or order, unless otherwise
specified, the order of the operations can be modified. Thus, the
illustrated embodiments should be understood only as examples, and
the illustrated operations can be performed in a different order,
while some operations can be performed in parallel. Additionally,
one or more operations can be omitted in some embodiments. Thus,
not all illustrated operations are required in every embodiment,
and other process flows are possible.
[0077] FIG. 6 is a flow diagram of an example method 600 of die
group management implemented by a memory sub-system controller
operating in accordance with some embodiments of the
disclosure.
[0078] At operation 610, the processing logic of the memory
sub-system controller programs one or more blocks at the memory
device. In some embodiments, the one or more blocks are associated
with a block family and with one or more dice of a die group.
[0079] At operation 620, processing logic determines, based on a
subset of dice of the die group, a voltage offset bin associated
with the die group and block family. In some embodiments, the
determination can be made based on one or more dice that are
representative of dice of the die group. In some embodiments, the
die group includes multiple dice. The one or more representative
dice are a subset of the dice of the die group.
[0080] In some embodiments, to determine the voltage offset bin
associated with the die group, processing logic determines a read
threshold voltage offset for the subset of dice of the die group.
Processing logic identifies, based on the read threshold voltage
offset for the subset of dice of the die group, the voltage offset
bin from an offset table of the metadata.
[0081] In some embodiments, to determine the voltage offset bin
associated with the die group is responsive to detecting a
triggering event. In some embodiments, the triggering event
corresponds to one of the counter meeting or exceeding a threshold
value or a power down event that clears the counter.
[0082] At operation 630, processing logic appends, to metadata
associated with the memory device, a record associating the die
group and block family with the voltage offset bin.
[0083] At operation 640, processing logic determines whether a
composition of dice of the die group is to be modified. In some
embodiments, the determination is responsive to detecting a
triggering event (e.g., number of PE cycles). In some embodiments,
the triggering event corresponds to a number of program-erase (PE)
cycles of the memory device meeting or exceeding a threshold number
of PE cycles.
[0084] In some embodiments, to determine whether the composition of
dice of the die group is to be modified, processing logic
determines values of a data state metric that characterize a
temporal voltage shift for each of the initial dice of the die
group. Processing logic determines, based on the values of the data
state metric, that the temporal voltage shift of one or more of the
initial dice of the die group is outside a range. Responsive to
determining that the temporal voltage shift of the one or more of
the initial dice of the die group is outside the range, processing
logic removes the one or more of the initial dice from the die
group.
[0085] In some embodiment, to determine whether the composition of
dice of the die group is to be modified, processing logic
determines other values of the data state metric that characterize
a temporal voltage shift for each of other dice that are not part
of the die group. Processing logic determines, based on the other
values of the data state metric that the temporal voltage shift of
one or more of the other dice is within the range. Responsive to
determining that the temporal voltage shift of the one or more of
the other dice is within the range, processing logic adds the one
or more of the other dice to the die group.
[0086] In some embodiments, to determine whether the composition of
dice of the die group is to be modified, processing logic
determines operational temperatures of the initial dice of the die
group. Processing logic determines that the operation temperatures
for one or more of the initial dice of the die group is outside a
temperature range. Responsive to determining that the operation
temperatures for the one or more of the initial dice of the die
group is outside the temperature range, processing logic removes
the one or more of the initial dice from the die group.
[0087] Responsive to determining that the composition of dice of
the die group is to be modified, processing logic proceeds to
operation 650. Responsive to determining that the composition of
the dice of the die group is not to be modified, processing logic
returns to operation 640 (e.g., waits for another triggering
event).
[0088] At operation 650, processing logic, changes the composition
of the dice of the die group from initial dice to different dice.
In some embodiments, the changing is performed responsive to
determining that the die group is to be modified.
[0089] FIG. 7 is a flow diagram of an example method 700 of
determining die groups, in accordance with some embodiments of the
disclosure. At operation 710, processing logic determines values of
a data state metric that characterizes a temporal voltage shift for
each die of a memory device (or memory sub-system).
[0090] At operation 720, processing logic determines, based on the
values of the data state metric that the temporal voltage shift of
an initial subset of the dice is within a range.
[0091] At operation 730, processing logic assigns the initial
subset of dice to the initial die group. The initial die group
corresponds to an offset table of metadata that identifies read
threshold voltage offsets for the initial die group.
[0092] At operation 740, processing logic determines, based on the
values of the data state metric, that the temporal voltage shift of
another subset of the dice is within another range.
[0093] At operation 750, processing logic assigns the other subset
of die to another die group. The initial die group and the other
die group correspond to different offset tables that identify
different read threshold voltage offsets.
[0094] At operation 760, processing logic determines operational
temperatures of the initial subset of dice of the initial die
group.
[0095] At operation 770, processing logic determines that the
operation temperatures for one or more of the initial subset of
dice of the initial die group is within a temperature range.
[0096] At operation 780, processing logic removes the one or more
of the initial subset of dice from the initial die group.
[0097] At operation 790, processing logic assigns the one or more
dice removed from the initial subset of dice to still another die
group.
[0098] In some embodiments, processing logic determines that the
operational temperatures for remaining dice of the initial subset
of dice of the initial die group are within a different temperature
range. The remaining dice remain assigned to the initial die
group.
[0099] FIG. 8 illustrates an example machine of a computer system
800 within which a set of instructions, for causing the machine to
perform any one or more of the methodologies discussed herein, can
be executed. In some embodiments, the computer system 800 can
correspond to a host system (e.g., the host system 120 of FIG. 1 or
2) that includes, is coupled to, or utilizes a memory sub-system
(e.g., the memory sub-system 110 of FIG. 1 or 2) or can be used to
perform the operations of a controller (e.g., to execute an
operating system to perform operations corresponding to the die
group manager component 113 of FIG. 1 or 2). In alternative
embodiments, the machine can be connected (e.g., networked) to
other machines in a LAN, an intranet, an extranet, and/or the
Internet. The machine can operate in the capacity of a server or a
client machine in client-server network environment, as a peer
machine in a peer-to-peer (or distributed) network environment, or
as a server or a client machine in a cloud computing infrastructure
or environment.
[0100] The machine can be a personal computer (PC), a tablet PC, a
set-top box (STB), a Personal Digital Assistant (PDA), a cellular
telephone, a web appliance, a server, a network router, a switch or
bridge, or any machine capable of executing a set of instructions
(sequential or otherwise) that specify actions to be taken by that
machine. Further, while a single machine is illustrated, the term
"machine" shall also be taken to include any collection of machines
that individually or jointly execute a set (or multiple sets) of
instructions to perform any one or more of the methodologies
discussed herein.
[0101] The example computer system 800 includes a processing device
802, a main memory 804 (e.g., read-only memory (ROM), flash memory,
dynamic random access memory (DRAM) such as synchronous DRAM
(SDRAM) or Rambus DRAM (RDRAM), etc.), a static memory 810 (e.g.,
flash memory, static random access memory (SRAM), etc.), and a data
storage system 818, which communicate with each other via a bus
830.
[0102] Processing device 802 represents one or more general-purpose
processing devices such as a microprocessor, a central processing
unit, or the like. More particularly, the processing device can be
a complex instruction set computing (CISC) microprocessor, reduced
instruction set computing (RISC) microprocessor, very long
instruction word (VLIW) microprocessor, or a processor implementing
other instruction sets, or processors implementing a combination of
instruction sets. Processing device 802 can also be one or more
special-purpose processing devices such as an application specific
integrated circuit (ASIC), a field programmable gate array (FPGA),
a digital signal processor (DSP), network processor, or the like.
The processing device 802 is configured to execute instructions 828
for performing the operations and steps discussed herein. The
computer system 800 can further include a network interface device
812 to communicate over the network 820.
[0103] The data storage system 818 can include a machine-readable
storage medium 824 (also known as a computer-readable medium) on
which is stored one or more sets of instructions 828 or software
embodying any one or more of the methodologies or functions
described herein. The instructions 828 can also reside, completely
or at least partially, within the main memory 804 and/or within the
processing device 802 during execution thereof by the computer
system 800, the main memory 804 and the processing device 802 also
constituting machine-readable storage media. The machine-readable
storage medium 824, data storage system 818, and/or main memory 804
can correspond to the memory sub-system 110 of FIG. 1 or 2.
[0104] In one embodiment, the instructions 828 include instructions
to implement functionality corresponding to the die group manager
component 113 of FIG. 1 or 2. While the machine-readable storage
medium 824 is shown in an example embodiment to be a single medium,
the term "machine-readable storage medium" should be taken to
include a single medium or multiple media that store the one or
more sets of instructions. The term "machine-readable storage
medium" shall also be taken to include any medium that is capable
of storing or encoding a set of instructions for execution by the
machine and that cause the machine to perform any one or more of
the methodologies of the disclosure. The term "machine-readable
storage medium" shall accordingly be taken to include, but not be
limited to, solid-state memories, optical media, and magnetic
media.
[0105] Some portions of the preceding detailed descriptions have
been presented in terms of algorithms and symbolic representations
of operations on data bits within a computer memory. These
algorithmic descriptions and representations are the ways used by
those skilled in the data processing arts to most effectively
convey the substance of their work to others skilled in the art. An
algorithm is here, and generally, conceived to be a self-consistent
sequence of operations leading to a desired result. The operations
are those requiring physical manipulations of physical quantities.
Usually, though not necessarily, these quantities take the form of
electrical or magnetic signals capable of being stored, combined,
compared, and otherwise manipulated. It has proven convenient at
times, principally for reasons of common usage, to refer to these
signals as bits, values, elements, symbols, characters, terms,
numbers, or the like.
[0106] It should be borne in mind, however, that all of these and
similar terms are to be associated with the appropriate physical
quantities and are merely convenient labels applied to these
quantities. The disclosure can refer to the action and processes of
a computer system, or similar electronic computing device, that
manipulates and transforms data represented as physical
(electronic) quantities within the computer system's registers and
memories into other data similarly represented as physical
quantities within the computer system memories or registers or
other such information storage systems.
[0107] The disclosure also relates to an apparatus for performing
the operations herein. This apparatus can be specially constructed
for the intended purposes, or it can include a general purpose
computer selectively activated or reconfigured by a computer
program stored in the computer. Such a computer program can be
stored in a computer readable storage medium, such as, but not
limited to, any type of disk including floppy disks, optical disks,
CD-ROMs, and magnetic-optical disks, read-only memories (ROMs),
random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical
cards, or any type of media suitable for storing electronic
instructions, each coupled to a computer system bus.
[0108] The algorithms and displays presented herein are not
inherently related to any particular computer or other apparatus.
Various general purpose systems can be used with programs in
accordance with the teachings herein, or it can prove convenient to
construct a more specialized apparatus to perform the method. The
structure for a variety of these systems will appear as set forth
in the description below. In addition, the disclosure is not
described with reference to any particular programming language. It
will be appreciated that a variety of programming languages can be
used to implement the teachings of the disclosure as described
herein.
[0109] The disclosure can be provided as a computer program
product, or software, that can include a machine-readable medium
having stored thereon instructions, which can be used to program a
computer system (or other electronic devices) to perform a process
according to the disclosure. A machine-readable medium includes any
mechanism for storing information in a form readable by a machine
(e.g., a computer). In some embodiments, a machine-readable (e.g.,
computer-readable) medium includes a machine (e.g., a computer)
readable storage medium such as a read only memory ("ROM"), random
access memory ("RAM"), magnetic disk storage media, optical storage
media, flash memory devices, etc. The words "example" or
"exemplary" are used herein to mean serving as an example,
instance, or illustration. Any aspect or design described herein as
"example" or "exemplary" is not necessarily to be construed as
preferred or advantageous over other aspects or designs. Rather,
use of the words "example" or "exemplary" is intended to present
concepts in a concrete fashion. As used in this application, the
term "or" is intended to mean an inclusive "or" rather than an
exclusive "or." That is, unless specified otherwise, or clear from
context, "X includes A or B" is intended to mean any of the natural
inclusive permutations. That is, if X includes A; X includes B; or
X includes both A and B, then "X includes A or B" is satisfied
under any of the foregoing instances. In addition, the articles "a"
and "an" as used in this application and the appended claims may
generally be construed to mean "one or more" unless specified
otherwise or clear from context to be directed to a singular form.
Moreover, use of the term "an embodiment" or "one embodiment" or
"an implementation" or "one implementation" or the like throughout
may or may not mean the same embodiment or implementation. One or
more embodiments or implementations described herein may be
combined in a particular embodiment or implementation. The terms
"first," "second," "third," "fourth," etc. as used herein are meant
as labels to distinguish among different elements and may not
necessarily have an ordinal meaning according to their numerical
designation.
[0110] In the foregoing specification, embodiments of the
disclosure have been described with reference to specific example
embodiments thereof. It will be evident that various modifications
can be made thereto without departing from the broader spirit and
scope of embodiments of the disclosure as set forth in the
following claims. The specification and drawings are, accordingly,
to be regarded in an illustrative sense rather than a restrictive
sense.
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