CREATING SEGMENTED SOURCE PLATES FOR SUB-BLOCK DEFINITION IN A MEMORY DEVICE

Abstract

A system for manufacturing a memory device forms a memory array comprising a plurality of memory cells arranged in a plurality of memory strings along a plurality of memory array pillars, wherein respective subsets of the memory array pillars correspond to respective sub-blocks of a block of the memory array, and forms a plurality of deintegrated source segments adjacent to the memory array, wherein the source segments of the plurality of deintegrated source segments are associated with respective sub-blocks and are physically segregated from one another.

Description

TECHNICAL FIELD

Embodiments of the disclosure relate generally to memory sub-systems, and more specifically, relate to creating segmented source plates for sub-block definition in a memory device of a memory sub-system.

BACKGROUND

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

The present disclosure will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the disclosure.

FIG. 1A illustrates an example computing system that includes a memory sub-system in accordance with some embodiments of the present disclosure.

FIG. 1B is a block diagram of a memory device in communication with a memory sub-system controller of a memory sub-system, in accordance with some embodiments of the present disclosure.

FIG. 2 is a schematic of portions of an array of memory cells as could be used in a memory of the type described with reference to FIG. 1B in accordance with some embodiments of the present disclosure.

FIG. 3 is a schematic of portions of an array of memory cells implementing non-segregated cells as a drain-side select gates and segmented source plates for sub-blocks in accordance with some embodiments of the present disclosure.

FIG. 4 is a block diagram of portions of an array of memory cells implementing sub-block definition using segmented source plates in accordance with some embodiments of the present disclosure.

FIG. 5 is a block diagram of portions of an array of memory cells with strapping across segmented source plates in accordance with some embodiments of the present disclosure.

FIG. 6 is a flow diagram of an example method of operation of a memory array implementing non-segregated cells as a drain-side select gates and segmented source plates for sub-blocks in accordance with some embodiments of the present disclosure.

FIGS. 7A-7G are diagrams illustrating a process flow for creating segmented source plates for sub-block definition in a memory device in accordance with some embodiments of the present disclosure.

FIG. 8 is a block diagram of an example computer system in which embodiments of the present disclosure can operate.

DETAILED DESCRIPTION

Aspects of the present disclosure are directed to creating segmented source plates for sub-block definition in a memory device of a memory sub-system. 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. 1A. 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.

A memory sub-system can include high density non-volatile memory devices where retention of data is desired when no power is supplied to the memory device. For example, NAND memory, such as 3D flash NAND memory, offers storage in the form of compact, high density configurations. A non-volatile memory device is a package of one or more dice, each including one or more planes. For some types of non-volatile memory devices (e.g., NAND memory), each plane includes of a set of physical blocks. Each block includes of a set of pages. Each page includes of a set of memory cells (“cells”). A cell is an electronic circuit that stores information. Depending on the cell type, a cell can store one or more bits of binary information, and has various logic states that correlate to the number of bits being stored. The logic states can be represented by binary values, such as “0” and “1”, or combinations of such values.

A memory device can be made up of bits arranged in a two-dimensional or a three-dimensional grid. Memory cells are formed onto a silicon wafer in an array of columns (also hereinafter referred to as bitlines) and rows (also hereinafter referred to as wordlines). A wordline can refer to one or more rows of memory cells of a memory device that are used with one or more bitlines to generate the address of each of the memory cells. The intersection of a bitline and wordline constitutes the address of the memory cell. A block hereinafter refers to a unit of the memory device used to store data and can include a group of memory cells, a wordline group, a wordline, or individual memory cells.

Memory pages (also referred to herein as “pages”) store one or more bits of binary data corresponding to data received from the host system. The memory cells of a block can be arranged along a number of separate wordlines. Each block can include a number of sub-blocks, where each sub-block is defined by one or more associated pillars (e.g., vertical conductive traces) extending between a shared bitline at one end and a source at the other end. Many memory devices utilize a common source plate that is shared by each sub-block in the block. Since the sub-blocks can be accessed separately (e.g., to perform program or read operations), the block can include a structure to selectively enable the pillar(s) associated with a certain sub-block, while disabling the pillars associated with other sub-blocks. This structure can include one or more select gate devices positioned at either or both ends of each pillar. Depending on a control signal applied, these select gate devices can either enable or disable the conduction of signals through the pillars.

Certain memory devices can implement these select gate devices using core memory cells (e.g., replacement gate transistors with a charge trapping structure). The replacement gate transistors are programmable devices and thus offer the benefit of high versatility when setting corresponding threshold voltages for the select gate devices. In general, the select gate devices associated with each pillar in the data block are controlled separately (e.g., by separate control signals) and the select gate devices themselves are physically segregated. Often, there is a cut or slit in the memory array (e.g., at a drain-side of the pillars) to physically delineate the select gate devices in separate sub-blocks from one another. Core memory cells are relatively large, however, and the pillar at the drain-end is relatively wide when the pillar is formed in a single processing step, leaving little space between sub-blocks to make such a physical cut or slit. Accordingly, other memory devices use different transistors (e.g., NMOS transistors) to form the select gate devices. Such transistors are smaller than core memory cells and can be deintegrated at the drain-end of the pillars (i.e., located at a portion of the pillar that is formed as a separate processing step from the rest of the pillar where the core memory cells are located). The threshold voltages of NMOS transistors are not programmable, however, and are fixed at the time of manufacture. This can lead to variations among the select gate devices in different sub-blocks, potentially causing reliability problems in the data stored in those sub-blocks.

Still other memory devices use non-segregated cells as drain-side select gates for sub-blocks in the memory device. For example, a block of the memory device can include a number of sub-blocks (e.g., four sub-blocks) and the same or a greater number of logical select gate layers (e.g., four layers) at a drain-side of the sub-blocks. Each of the logical select gate layers can include one select gate device associated with each sub-block, and each sub-block can be associated with one select gate device in each of the logical select gate layers. The select gate devices in each layer can be formed using core memory cells (e.g., replacement gate transistors with a charge trapping structure) and are non-segregated, such that they are each coupled to a shared wordline and controlled by a same control signal. The select gate devices in the logical select gate layers can be programmed with threshold voltages in a certain pattern such that the application of control signals having specific voltages on the wordlines can selectively activate one of the sub-blocks at a time. When such a design is utilized for the drain-side select gates, many memory devices further include segregated select gate devices at the source-side of each sub-block, which can be used to selectively activate different sub-blocks during programming of the drain-side select gate devices in the logical select gate layers into the specific pattern of threshold voltages. These source-side select gate devices can be physically segregated by a cut or slice, can be formed using a different technology (e.g., NMOS transistors) than the core memory cells, and can be deintegrated at the source-end of the sub-block pillars (i.e., located at a portion of the pillar that is formed as a separate processing step from the rest of the pillar where the core memory cells are located). The separate processing step, however, increases the complexity of each block, thereby detrimentally impacting the overall cost of the memory device. In addition, the physical segmentation of the source-side select gate devices (i.e., the cuts between each device) increases the size of the block and reduces the available area on the memory die for other components.

Aspects of the present disclosure address the above and other deficiencies by creating segmented source plates for sub-block definition in a memory device of a memory sub-system. In one embodiment, rather than utilizing a common source plate, the source can be physically segmented (e.g., by using cuts or slices) so that a separate segment is associated with each sub-block. Such a memory device can further implement the non-segregated logical select gate layers at a drain-side of the sub-blocks, including memory cells that can be programmed with threshold voltages in a certain pattern such that the application of control signals having specific voltages on the wordlines can selectively activate one of the sub-blocks at a time. During the programming of these memory cells, control logic can apply separate source voltages to the individual source plate segments to selectively activate different sub-blocks (e.g., a source voltage of 0V for the source plate segment of the selected sub-block and a source voltage of Vcc for the source plate segments of the unselected sub-blocks).

Advantages of this approach include, but are not limited to, simplified fabrication of the memory device. The segmented source plate design described herein prevents the need to fabricate a dedicated module for the select gate device with shorter pillars having a narrower critical dimension than other pillars in the array in order to physically segregate the devices. In addition, core memory cells can be in the logical select gate layers at the drain-side, as well as in the select gate devices at the source-side, which offer the benefit of programmable threshold voltages over the smaller NMOS transistors. Accordingly, the threshold voltages can be more accurately tuned, leading to improved performance in the memory device.

FIG. 1A illustrates an example computing system 100 that includes a memory sub-system 110 in accordance with some embodiments of the present 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.

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 modules (NVDIMMs).

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.

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-system 110. FIG. 1A 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.

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, CXL 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.

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 compute express link (CXL) 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)), 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 the memory components (e.g., memory devices 130) when the memory sub-system 110 is coupled with the host system 120 by the physical host interface (e.g., PCIe, CXL). 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. 1A 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.

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).

Some examples of non-volatile memory devices (e.g., memory device 130) include not-and (NAND) type flash memory and write-in-place memory, such as three-dimensional cross-point (“3D cross-point”) memory. 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).

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.

Although non-volatile memory components such as a 3D cross-point array of non-volatile memory cells and NAND type flash 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), not-or (NOR) flash memory, electrically erasable programmable read-only memory (EEPROM).

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 a 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.

The memory sub-system controller 115 can include a processor 117 (e.g., a 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.

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. 1A has been illustrated as including the memory sub-system controller 115, in another embodiment of the present disclosure, a memory sub-system 110 does not include a memory sub-system 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).

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.

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 memory sub-system controller 115 and decode the address to access the memory devices 130.

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 130 having control logic (e.g., local controller 135) on the die and a controller (e.g., memory sub-system controller 115) for media management within the same memory device package. An example of a managed memory device is a managed NAND (MNAND) device. Memory device 130, for example, can represent a single die having some control logic (e.g., local media controller 135) embodied thereon. In some embodiments, one or more components of memory sub-system 110 can be omitted.

In one embodiment, memory sub-system 110 includes a memory interface component 113. Memory interface component 113 is responsible for handling interactions of memory sub-system controller 115 with the memory devices of memory sub-system 110, such as memory device 130. For example, memory interface component 113 can send memory access commands corresponding to requests received from host system 120 to memory device 130, such as program commands, read commands, or other commands. In addition, memory interface component 113 can receive data from memory device 130, such as data retrieved in response to a read command or a confirmation that a program command was successfully performed. In some embodiments, the memory sub-system controller 115 includes at least a portion of the memory interface 113. For example, the memory sub-system controller 115 can include a processor 117 (e.g., a processing device) configured to execute instructions stored in local memory 119 for performing the operations described herein. In some embodiments, the memory interface component 113 is part of the host system 110, an application, or an operating system.

In one embodiment, memory device 130 includes local media controller 135 and a memory array 104. As described herein, the memory array 104 can include a number of blocks, where each block includes a number of sub-blocks. In one embodiment, each block includes a number of logical select gate layers (logical SGD) 150 at a drain-side of the sub-blocks. The number of logical select gate layers 150 can be greater than or equal to the number of sub-blocks. For example, if a block includes four sub-blocks, there can be four logical select gate layers 150. Similarly, if a block includes eight sub-blocks, there can be eight logical select gate layers 150. In addition, if a block includes three sub-blocks, there could still be four logical select gate layers, for example. In one embodiment, the select gate devices in each layer are formed using core memory cells (e.g., replacement gate transistors with a charge trapping structure) and are non-segregated, such that they are each coupled to a shared wordline and controlled by a same control signal. In one embodiment, the select gate devices in the logical select gate layers 150 are programmed with threshold voltages in a certain pattern such that the application of control signals from local media controller 135 having specific voltages on the wordlines can selectively activate one of the sub-blocks at a time. For example, each logical select gate layer can have half of the select gate devices programmed with a high threshold voltage and half of the select gate devices programmed with a low threshold voltage, while each sub-block has select gate devices in half of the logical select gate layers programmed with the high threshold voltage and select gate devices in half of the logical select gate layers programmed with the low threshold voltage.

In addition, in one embodiment, each block in the memory array 104 can have a segmented source (SRC) plate 180. For example, rather than utilizing a common source plate, the source plate 180 can be deintegrated (i.e., physically segmented by using cuts or slices) so that a separate segment is associated with each sub-block in the memory array 104. Depending on the embodiment, the number of source segments can be equal to the number of sub-blocks. For example, if there are four sub-blocks, there can be four source segments. Similarly, if there are eight sub-blocks, there can be eight source segments. In one embodiment, during the programming of the select gate devices in the logical select gate layers 150, control logic can apply separate source voltages to the individual source plate segments to selectively activate different sub-blocks (e.g., a source voltage of 0V for the source plate segment of the selected sub-block and a source voltage of Vcc for the source plate segments of the unselected sub-blocks). Further details with regards to the structure and operation of the logical select gate layers 150 and the segmented source plate 180 are described below.

FIG. 1B is a simplified block diagram of a first apparatus, in the form of a memory device 130, in communication with a second apparatus, in the form of a memory sub-system controller 115 of a memory sub-system (e.g., memory sub-system 110 of FIG. 1A), according to an embodiment. Some examples of electronic systems include personal computers, personal digital assistants (PDAs), digital cameras, digital media players, digital recorders, games, appliances, vehicles, wireless devices, mobile telephones and the like. The memory sub-system controller 115 (e.g., a controller external to the memory device 130), may be a memory controller or other external host device.

Memory device 130 includes an array of memory cells 104 logically arranged in rows and columns. Memory cells of a logical row are typically connected to the same access line (e.g., a wordline) while memory cells of a logical column are typically selectively connected to the same data line (e.g., a bit line). A single access line may be associated with more than one logical row of memory cells and a single data line may be associated with more than one logical column. Memory cells (not shown in FIG. 1B) of at least a portion of array of memory cells 104 are capable of being programmed to one of at least two target data states. In one embodiment, the memory array 104 includes a number of logical select gate layers (logical SGD) 150 at a drain-side of each sub-block in the array 104 and a segmented source (SRC) plate 180 with a separate source segment associated with each sub-block in the array 104.

Row decode circuitry 108 and column decode circuitry 109 are provided to decode address signals. Address signals are received and decoded to access the array of memory cells 104. Memory device 130 also includes input/output (I/O) control circuitry 160 to manage input of commands, addresses and data to the memory device 130 as well as output of data and status information from the memory device 130. An address register 114 is in communication with I/O control circuitry 160 and row decode circuitry 108 and column decode circuitry 109 to latch the address signals prior to decoding. A command register 124 is in communication with I/O control circuitry 160 and local media controller 135 to latch incoming commands.

A controller (e.g., the local media controller 135 internal to the memory device 130) controls access to the array of memory cells 104 in response to the commands and generates status information for the external memory sub-system controller 115, i.e., the local media controller 135 is configured to perform access operations (e.g., read operations, programming operations and/or erase operations) on the array of memory cells 104. The local media controller 135 is in communication with row decode circuitry 108 and column decode circuitry 109 to control the row decode circuitry 108 and column decode circuitry 109 in response to the addresses.

The local media controller 135 is also in communication with a cache register 172. Cache register 172 latches data, either incoming or outgoing, as directed by the local media controller 135 to temporarily store data while the array of memory cells 104 is busy writing or reading, respectively, other data. During a program operation (e.g., write operation), data may be passed from the cache register 172 to the data register 170 for transfer to the array of memory cells 104; then new data may be latched in the cache register 172 from the I/O control circuitry 160. During a read operation, data may be passed from the cache register 172 to the I/O control circuitry 160 for output to the memory sub-system controller 115; then new data may be passed from the data register 170 to the cache register 172. The cache register 172 and/or the data register 170 may form (e.g., may form a portion of) a page buffer of the memory device 130. A page buffer may further include sensing devices (not shown in FIG. 1B) to sense a data state of a memory cell of the array of memory cells 104, e.g., by sensing a state of a data line connected to that memory cell. A status register 122 may be in communication with I/O control circuitry 160 and the local memory controller 135 to latch the status information for output to the memory sub-system controller 115.

Memory device 130 receives control signals at the memory sub-system controller 115 from the local media controller 135 over a control link 132. For example, the control signals can include a chip enable signal CE #, a command latch enable signal CLE, an address latch enable signal ALE, a write enable signal WE #, a read enable signal RE #, and a write protect signal WP #. Additional or alternative control signals (not shown) may be further received over control link 132 depending upon the nature of the memory device 130. In one embodiment, memory device 130 receives command signals (which represent commands), address signals (which represent addresses), and data signals (which represent data) from the memory sub-system controller 115 over a multiplexed input/output (I/O) bus 134 and outputs data to the memory sub-system controller 115 over I/O bus 134.

For example, the commands may be received over input/output (I/O) pins [7:0] of I/O bus 134 at I/O control circuitry 160 and may then be written into command register 124. The addresses may be received over input/output (I/O) pins [7:0] of I/O bus 134 at I/O control circuitry 160 and may then be written into address register 114. The data may be received over input/output (I/O) pins [7:0] for an 8-bit device or input/output (I/O) pins [15:0] for a 16-bit device at I/O control circuitry 160 and then may be written into cache register 172. The data may be subsequently written into data register 170 for programming the array of memory cells 104.

In an embodiment, cache register 172 may be omitted, and the data may be written directly into data register 170. Data may also be output over input/output (I/O) pins [7:0] for an 8-bit device or input/output (I/O) pins [15:0] for a 16-bit device. Although reference may be made to I/O pins, they may include any conductive node providing for electrical connection to the memory device 130 by an external device (e.g., the memory sub-system controller 115), such as conductive pads or conductive bumps as are commonly used.

It will be appreciated by those skilled in the art that additional circuitry and signals can be provided, and that the memory device 130 of FIG. 1B has been simplified. It should be recognized that the functionality of the various block components described with reference to FIG. 1B may not necessarily be segregated to distinct components or component portions of an integrated circuit device. For example, a single component or component portion of an integrated circuit device could be adapted to perform the functionality of more than one block component of FIG. 1B. Alternatively, one or more components or component portions of an integrated circuit device could be combined to perform the functionality of a single block component of FIG. 1B. Additionally, while specific I/O pins are described in accordance with popular conventions for receipt and output of the various signals, it is noted that other combinations or numbers of I/O pins (or other I/O node structures) may be used in the various embodiments.

FIG. 2 is a schematic of portions of an array of memory cells 104, such as a NAND memory array, as could be used in a memory of the type described with reference to FIG. 1B according to an embodiment. Memory array 104 includes access lines, such as wordlines 202₀ to 202_N, and data lines, such as bit lines 204₀ to 204_M. The wordlines 202 can be connected to global access lines (e.g., global wordlines), not shown in FIG. 2, in a many-to-one relationship. For some embodiments, memory array 104 can be formed over a semiconductor that, for example, can be conductively doped to have a conductivity type, such as a p-type conductivity, e.g., to form a p-well, or an n-type conductivity, e.g., to form an n-well.

Memory array 104 can be arranged in rows (each corresponding to a wordline 202) and columns (each corresponding to a bit line 204). Each column can include a string of series-connected memory cells (e.g., non-volatile memory cells), such as one of NAND strings 206₀ to 206_M. Each NAND string 206 can be connected (e.g., selectively connected) to a respective source (SRC) segment (e.g., segment 216) and can include memory cells 208₀ to 208_N. The memory cells 208 can represent non-volatile memory cells for storage of data. The memory cells 208 of each NAND string 206 can be connected in series between a select gate 210 (e.g., a field-effect transistor), such as one of the select gates 210₀ to 210_M (e.g., that can be source select transistors, commonly referred to as select gate source), and a select gate 212 (e.g., a field-effect transistor), such as one of the select gates 212₀ to 212_M (e.g., that can be drain select transistors, commonly referred to as select gate drain). Select gates 210₀ to 210_M can be commonly connected to a select line 214, such as a source select line (SGS), and select gates 212₀ to 212_M can be commonly connected to a select line 215, such as a drain select line (SGD). Although depicted as traditional field-effect transistors, the select gates 210 and 212 can utilize a structure similar to (e.g., the same as) the memory cells 208. The select gates 210 and 212 can represent a number of select gates connected in series, with each select gate in series configured to receive a same or independent control signal. Although not illustrated in FIG. 2, in one embodiment, memory array 104 can include a number of logical select gate layers (i.e., represented by logical SGD 150) at a drain-side of the sub-blocks.

A source of each select gate 210 can be connected to an associated segment of the segmented source plate 180, such as segment 216. The drain of each select gate 210 can be connected to a memory cell 208₀ of the corresponding NAND string 206. For example, the drain of select gate 210₀ can be connected to memory cell 208₀ of the corresponding NAND string 206₀. Therefore, each select gate 210 can be configured to selectively connect a corresponding NAND string 206 to the respective source segment 216. A control gate of each select gate 210 can be connected to the select line 214.

The drain of each select gate 212 can be connected to the bit line 204 for the corresponding NAND string 206. For example, the drain of select gate 212₀ can be connected to the bit line 204₀ for the corresponding NAND string 206₀. The source of each select gate 212 can be connected to a memory cell 208_N of the corresponding NAND string 206. For example, the source of select gate 212₀ can be connected to memory cell 208_N of the corresponding NAND string 206₀. Therefore, each select gate 212 can be configured to selectively connect a corresponding NAND string 206 to the corresponding bit line 204. A control gate of each select gate 212 can be connected to select line 215.

The memory array 104 in FIG. 2 can be a quasi-two-dimensional memory array and can have a generally planar structure, e.g., where the source segments 216, NAND strings 206 and bit lines 204 extend in substantially parallel planes. Alternatively, the memory array 104 in FIG. 2 can be a three-dimensional memory array, e.g., where NAND strings 206 can extend substantially perpendicular to a plane containing the source segments 216 and to a plane containing the bit lines 204 that can be substantially parallel to the plane containing the source segments 216.

Typical construction of memory cells 208 includes a data-storage structure 234 (e.g., a floating gate, charge trap, and the like) that can determine a data state of the memory cell (e.g., through changes in threshold voltage), and a control gate 236, as shown in FIG. 2. The data-storage structure 234 can include both conductive and dielectric structures while the control gate 236 is generally formed of one or more conductive materials. In some cases, memory cells 208 can further have a defined source/drain (e.g., source) 230 and a defined source/drain (e.g., drain) 232. The memory cells 208 have their control gates 236 connected to (and in some cases form) a wordline 202.

A column of the memory cells 208 can be a NAND string 206 or a number of NAND strings 206 selectively connected to a given bit line 204. A row of the memory cells 208 can be memory cells 208 commonly connected to a given wordline 202. A row of memory cells 208 can, but need not, include all the memory cells 208 commonly connected to a given wordline 202. Rows of the memory cells 208 can often be divided into one or more groups of physical pages of memory cells 208, and physical pages of the memory cells 208 often include every other memory cell 208 commonly connected to a given wordline 202. For example, the memory cells 208 commonly connected to wordline 202_N and selectively connected to even bit lines 204 (e.g., bit lines 204₀, 204₂, 204₄, etc.) can be one physical page of the memory cells 208 (e.g., even memory cells) while memory cells 208 commonly connected to wordline 202_N and selectively connected to odd bit lines 204 (e.g., bit lines 204₁, 204₃, 204₅, etc.) can be another physical page of the memory cells 208 (e.g., odd memory cells).

Although bit lines 204₃-204₅ are not explicitly depicted in FIG. 2, it is apparent from the figure that the bit lines 204 of the array of memory cells 104 can be numbered consecutively from bit line 204₀ to bit line 204_M. Other groupings of the memory cells 208 commonly connected to a given wordline 202 can also define a physical page of memory cells 208. For certain memory devices, all memory cells commonly connected to a given wordline can be deemed a physical page of memory cells. The portion of a physical page of memory cells (which, in some embodiments, could still be the entire row) that is read during a single read operation or programmed during a single programming operation (e.g., an upper or lower page of memory cells) can be deemed a logical page of memory cells. A block of memory cells can include those memory cells that are configured to be erased together, such as all memory cells connected to wordlines 202₀-202_N (e.g., all NAND strings 206 sharing common wordlines 202). Unless expressly distinguished, a reference to a page of memory cells herein refers to the memory cells of a logical page of memory cells. Although the example of FIG. 2 is discussed in conjunction with NAND flash, the embodiments and concepts described herein are not limited to a particular array architecture or structure, and can include other structures (e.g., SONOS, phase change, ferroelectric, etc.) and other architectures (e.g., AND arrays, NOR arrays, etc.).

FIG. 3 is a schematic of portions of an array of memory cells implementing non-segregated cells as a drain-side select gates for sub-blocks in accordance with some embodiments of the present disclosure. The portion of the array of memory cells, such as memory array 104, can be a block 300, for example. In one embodiment, the block 300 includes strings of memory cells that can be grouped into sub-blocks, such as sub-blocks 305₀-305₃. Other numbers of sub-blocks can be included in other embodiments.

Specifically, in at least some embodiments, the block 300 includes a bit line 304, where each sub-block is coupled to the bit line 304 and to respective source (SRC) segment, such as one of deintegrated source segments 302₀-302₃. The first sub-block 305₀ can include a first string of memory cells 306₀ coupled therebetween. The second sub-block 305₁ can include a second string of memory cells 306₁ coupled therebetween. The third sub-block 305₂ can include a third string of memory cells 306₂ coupled therebetween. The fourth sub-block 305₃ can include a fourth string of memory cells 306₃ coupled therebetween. By way of example, the first string of memory cells 306₀ includes multiple memory cells 308₀ . . . 308_N. In at least some embodiments, multiple wordlines (WLs) are coupled with gates of memory cells of each string of memory cells 306₀ . . . 306₃. Each sub-block also includes a respective source select (SGS) transistor 310₀-310₃. Each SGS transistor can be connected to a respective source segment, to provide voltage to the sources of the multiple memory cells 308₀ . . . 308_N. In one embodiment, the source select gate transistors 310₀-310₃ are formed using core memory cells (e.g., replacement gate transistors with a charge trapping structure) and are non-segregated, such that the transistors are each coupled to a shared wordline and controlled by a same control signal (e.g., D-SGS). In one embodiment, source select gate transistor 310₀ is coupled to source segment 302₀, which is controlled by a respective control signal SRC0, source select gate transistor 310₁ is coupled to source segment 302₁, which is controlled by a respective control signal SRC1, source select gate transistor 310₂ is coupled to source segment 302₂, which is controlled by a respective control signal SRC2, and source select gate transistor 310₃ is coupled to source segment 302₃, which is controlled by a respective control signal SRC3.

In one embodiment, block 300 includes one or more drain-side gate induced drain leakage (GIDL) generator layers 320 having one or more gate induced drain leakage generator devices associated with respective sub-blocks 305₀-305₃ and coupled to bit line 304. The gate induced drain leakage generator devices in each layer can be connected to a common gate line GIDL, for example.

In one embodiment, block 300 includes a number of logical select gate layers 150 including select gate devices associated with respective sub-blocks 305₀-305₃. The number of logical select gate layers 150 can be greater than or equal to the number of sub-blocks 305₀-305₃. In one embodiment, the select gate devices in each of the logical select gate layers 150 are formed using core memory cells (e.g., replacement gate transistors with a charge trapping structure) and are non-segregated, such that devices in each layer are each coupled to a shared wordline and controlled by a same respective control signal (e.g., SGD0, SGD1, SGD2, SGD3).

In one embodiment, block 300 includes one or more logical select gate control layers 330 having one or more select gate devices associated with respective sub-blocks 305₀-305₃. The select gate devices in each layer can be connected to a common gate line vSGD control, for example. The logical select gate control layer 330 can be located further from the drain-side edge of the block 300 than the logical select gate layers and can include select gate devices with more finely tuned threshold voltages that the select gate devices in the logical select gate layers, which can be more coarsely programmed. In certain implementations, there can be more than one logical select gate control layer in block 300. In addition, the logical select gate control layer(s) could instead be positioned directly above strings of memory cells 306₀ . . . 306₃ or there could be additional logical select gate control layers positioned directly above strings of memory cells 306₀ 306₃ (e.g., below dummy wordline Dummy_3 344).

In one embodiment, block 300 includes a number of dummy wordlines located between other layers. For example, dummy wordline Dummy_1 340 can be located between drain-side gate induced drain leakage generator layer 320 and logical select gate layers 150, dummy wordline Dummy_2 342 can be located between logical select gate layers 150 and logical select gate control layer 330, dummy wordline Dummy_3 344 can be located between logical select gate control layer 330 and strings of memory cells 306₀ . . . 306₃, and dummy wordline Dummy_4 346 can be located between strings of memory cells 306₀ . . . 306₃ and source select transistors 310₀-310₃. Each dummy wordline can include memory cells associated with respective sub-blocks 305₀-305₃, but these memory cells are generally not used for storing data. Depending on the embodiment, there can be more than one dummy wordline at the positions of Dummy_1 340, Dummy_2 342, Dummy_3 344, and/or Dummy_4 346.

In one embodiment, the select gate devices in the logical select gate layers 150 are programmed with threshold voltages in a certain pattern such that the application of control signals (e.g., SGD0, SGD1, SGD2, SGD3) from local media controller 135 having specific voltages on the wordlines can selectively activate one of the sub-blocks 305₀-305₃ at a time. In one embodiment, each of logical select gate layers 150 can have half of the select gate devices programmed with a high threshold voltage and half of the select gate devices programmed with a low threshold voltage, while each of sub-blocks 305₀-305₃ has select gate devices in half of the logical select gate layers 150 programmed with the high threshold voltage and select gate devices in half of the logical select gate layers 150 programmed with the low threshold voltage. One example pattern is illustrated in block 300 of FIG. 3, however, other patterns are possible.

As illustrated, one layer of logical select gate layers 150 (i.e.., the layer controlled by SGD0) includes select gate devices 352₀-352₃, where each device is associated with one of sub-blocks 305₀-305₃. In this embodiment, select gate devices 352₁ and 352₃ are programmed with the high (H) threshold voltage (e.g., 7V) and select gate devices 352₀ and 352₂ are programmed with the low (L) threshold voltage (e.g., 3V). In other embodiments, the high and low threshold voltages can have different values. Another layer of logical select gate layers 150 (i.e., the layer controlled by SGD1) includes select gate devices 354₀-354₃, where each device is associated with one of sub-blocks 305₀-305₃. In this embodiment, select gate devices 354₀ and 354₂ are programmed with the high (H) threshold voltage (e.g., 7V) and select gate devices 354₁ and 354₃ are programmed with the low (L) threshold voltage (e.g., 3V). Another layer of logical select gate layers 150 (i.e., the layer controlled by SGD2) includes select gate devices 356₀-356₃, where each device is associated with one of sub-blocks 305₀-305₃. In this embodiment, select gate devices 356₂ and 356₃ are programmed with the high (H) threshold voltage (e.g., 7V) and select gate devices 356₀ and 356₁ are programmed with the low (L) threshold voltage (e.g., 3V). Another layer of logical select gate layers 150 (i.e.., the layer controlled by SGD3) includes select gate devices 358₀-358₃, where each device is associated with one of sub-blocks 305₀-305₃. In this embodiment, select gate devices 358₀ and 358₁ are programmed with the high (H) threshold voltage (e.g., 7V) and select gate devices 358₂ and 358₃ are programmed with the low (L) threshold voltage (e.g., 3V). Accordingly, sub-block 305₀ includes select gate devices 354₀ and 358₀ programmed with the high threshold voltage and select gate devices 352₀ and 356₀ programmed with the low threshold voltage. Sub-block 305₁ includes select gate devices 352₁ and 358₁ programmed with the high threshold voltage and select gate devices 354₁ and 356₁ programmed with the low threshold voltage. Sub-block 305₂ includes select gate devices 354₂ and 356₂ programmed with the high threshold voltage and select gate devices 351₂ and 358₂ programmed with the low threshold voltage. Sub-block 305₃ includes select gate devices 352₃ and 356₃ programmed with the high threshold voltage and select gate devices 354₃ and 358₃ programmed with the low threshold voltage.

When the threshold voltages of the select gate devices in logical select gate layers 150 are programmed in this or a similar pattern, the application of control signals (e.g., SGD0, SGD1, SGD2, SGD3) from local media controller 135 can selectively activate one of the sub-blocks 305₀-305₃ at a time. Table 1 illustrates one example of the control signals that can be applied to the wordlines of logical select gate layers 150 in order to activate each specific sub-block.

TABLE 1
				Activated
SGD3	SGD2	SGD1	SGD0	Sub-block
7 V	3 V	7 V	3 V	3050
7 V	3 V	3 V	7 V	3051
3 V	7 V	7 V	3 V	3052
3 V	7 V	3 V	7 V	3053

In general, if the control signal applied to a certain wordline has a high voltage (e.g., 7V) then all select gate devices on that wordline with a threshold voltage at or below the high voltage will turn on. Similarly, if the control signal has a low voltage (e.g., 3 V) then only the select gate devices on that wordline with a threshold voltage at the low voltage will turn on, while those select gate devices with a high threshold voltage will remain turned off. By way of example, if it is desired to activate sub-block 305₀ while sub-blocks 305₁-305₃ remain deactivated, the following set of control signals can be applied to the wordlines of logical select gate layers 150. A high voltage is applied at SGD3 causing select gate device 358₀ having a high threshold voltage to turn on, a low voltage is applied at SGD2 causing select gate device 356₀ having a low threshold voltage to turn on, a high voltage is applied at SGD1 causing select gate device 354₀ having a high threshold voltage to turn on, and a low voltage is applied at SGD0 causing select gate device 352₀ having a low threshold voltage to turn on. Thus, all of the select gate devices in sub-block 305₀ are activated. At the same time, however, the low voltage at SGD0 causes select gate device 352₁ having a high threshold voltage to remain off, thereby deactivating sub-block 305₁, the low voltage at SGD2 causes select gate device 356₂ having a high threshold voltage to remain off, thereby deactivating sub-block 305₂, and the low voltage at SGD0 causes select gate device 352₃ having a high threshold voltage to remain off, thereby deactivating sub-block 305₃. Similarly, the other sets of control signals can be applied to the wordlines of logical select gate layers 150 to activate the other sub-blocks.

As described above, the select gate devices in logical select gate layers 150 can be formed using core memory cells, such as replacement gate transistors with a charge trapping structure, and thus, have programmable threshold voltages. In one embodiment, the select gate devices are programmed with a specific threshold voltage pattern by applying certain voltage signals SRC0-SRC3 to the respective source segments 302₀-302₃. For example, to program select gate device 358₀ (e.g., to a high threshold voltage), local media controller 135 can cause a control signal D-SGS (e.g., having a magnitude of the supply voltage Vcc) to be applied at the gate of the first SGS transistor 310₀ in sub-block 305₀ to activate the first SGS transistor 310₀ and allow a voltage from the source segment 302₀ (e.g., a ground voltage provided by source control signal SRC0) to fill the channel of sub-block 305₀. The remaining SGS transistors 310₁-310₃ will also be activated by the control signal D-SGS, however, the respective source segments 302₁-302₃ can be driven to the supply voltage Vcc by control signals SRC1-SRC3 thereby causing the channels of sub-blocks 305₁-305₃ to be floating (e.g., up to 10V). Local media controller 135 can further cause a program voltage pulse (e.g., 20V) to be applied to the gate of select gate device 358₀ via control signal SGD3. The gate-channel potential difference at select gate device 358₀ will be large enough to program select gate device 358₀ while the other memory devices in the same logical select gate layer, but associated with different sub-blocks, are not programmed. Depending on the embodiment, a number of program pulses can be applied in order to bring the select gate device 358₀ to a desired threshold voltage level (e.g., 7V). A similar process can be repeated for the remaining select gate devices in sub-block 305₀ (i.e., select gate devices 356₀, 354₀, 352₀) while the first source segment 302₀ remains at the supply voltage. Once complete, local media controller 135 can move on to sub-block 305₁, drive the source segment 302₁ with the ground voltage while the other source segments 302₀, 302₂, and 303₃ are driven to the supply voltage, and proceed similarly. Once all of the select gate transistors in logical select gate layers 150 have been programmed to the appropriate pattern of threshold voltages, local media controller 135 can similarly program the devices in logical select gate control layer 330, and the memory cells on wordlines WL₀-WL_N.

FIG. 4 is a block diagram of portions of an array of memory cells implementing sub-block definition using segmented source plates in accordance with some embodiments of the present disclosure. The illustrated portion 400 shows two adjacent blocks (i.e., Block0 and Block1) each including four sub-blocks (i.e., SB0-SB3). Either of Block0 or Block1 can be represented by block 300 of FIG. 3. As further illustrated, the adjacent blocks can share a common bitline 404, and can each have respective set of wordlines 410 that form memory cells as the corresponding intersections with the pillars of each sub-block. Although each sub-block is illustrated as including one pillar in FIG. 4, it should be understood that in other embodiments, each sub-block can include any number of pillars (e.g., two, four, etc.). In one embodiment, the memory cells associated with some number of the wordlines (e.g., those adjacent to the common bitline 404) in each block can serve as the logical select gate layers to selectively control access to the corresponding sub-blocks in each block. In addition, each block can include a respective set of deintegrated source segments that are associated with respective sub-blocks and are physically segregated from one another. For example, each of SB0-SB3 in Block0 has a respective source segment and each of SB0-SB3 in Block1 has a respective source segment. As illustrated the source segments can be physically segregated, such as by a cut or slice formed during the processing steps when each of Block0 and Block1 are formed. Accordingly, each source segment is electronically separate and can be controlled by a respective source control signal (i.e. SRC0-SRC3). Thus, depending on the operations being performed on Block0 and Block1, different source control signals can be applied to the source segments associated with different sub-blocks within either Block0 or Block1.

In one embodiment, each of the deintegrated source segments of a given block, such as Block0 for example, is electrically connected to one or more corresponding source segments in each other block in the array of memory cells. For example, the source segment associated with SB0 in Block0 is connected to the source segment associated with SB0 in Block1, as well as to the source segment associated with SB0 in any other blocks (not shown). Similarly, the source segments associated with SB1-SB3 in Block0 are connected to the source segments associated with the corresponding SB1-SB3 in Block1, as well as to the source segments associated with SB1-SB3 in any other blocks (not shown). In one embodiment, signal lines connected to the corresponding source segments can be routed under the blocks of the memory array, as illustrated in FIG. 4. In other embodiments, some other signal connection between corresponding source segments can be used.

FIG. 5 is a block diagram of portions of an array of memory cells with strapping across segmented source plates in accordance with some embodiments of the present disclosure. The illustrated portion 500 shows a top-down view of the deintegrated source segments from two adjacent blocks (i.e., Block0 and Block1) each including four sub-blocks (i.e., SB0-SB3). Either of Block0 or Block 1 can be represented by block 300 of FIG. 3. In the illustrated embodiment, the corresponding source segments from each block are electrically connected via a number of signal connections 502, 504, 506. Although three sets of signal connections are illustrated in FIG. 5, it should be understood that some other number of signal connections could be utilized. In one embodiment, the source segments associated with corresponding sub-blocks can be physically connected when the corresponding sub-blocks are adjacent to one another in the structure of the memory array. For example, as shown in the illustrated portion 500, the source segment associated with SB3 of Block0 and the source segment associated with SB3 of Block1 are adjacent to one another and are physically connected (i.e., such that they are effectively a single segment and can be driven by control signal SRC3). If another block were located adjacent to Block1 (i.e., opposite Block0), the source segment associated with SB0 of Block1 could be physically connected with a source segment associated with SB0 of this additional block.

FIG. 6 is a flow diagram of an example method of operation of a memory array implementing non-segregated cells as a drain-side select gates and segmented source plates for sub-blocks in accordance with some embodiments of the present disclosure. The method 600 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, the method 600 is performed by local media controller 135 of FIG. 1A and FIG. 1B. Although shown in a particular sequence or order, unless otherwise specified, the order of the processes can be modified. Thus, the illustrated embodiments should be understood only as examples, and the illustrated processes can be performed in a different order, and some processes can be performed in parallel. Additionally, one or more processes can be omitted in various embodiments. Thus, not all processes are required in every embodiment. Other process flows are possible.

At operation 605, control signals are applied. For example, control logic (e.g., local media controller 135) can cause a plurality of source control signals (e.g., SRC0-SRC3) to be applied to a plurality of deintegrated source segments (e.g., 302₀-302₃) of a first block (e.g., block 300) of a plurality of blocks of a memory array (e.g., array 104) of a memory device (e.g., memory device 130) to selectively activate a plurality of sub-blocks (e.g., 305₀-305₃) of the first block. In one embodiment, the source segments of the plurality of deintegrated source segments are associated with respective sub-blocks and are physically segregated from one another. In one embodiment, to selectively activate a first sub-block (e.g., sub-block 305₀) of the plurality of sub-blocks, causing the plurality of source control signals to be applied to the plurality of deintegrated source segments comprises causing a ground voltage (e.g., 0V) to be applied to a first source segment 302₀ associated with the first sub-block 305₀ and causing a positive supply voltage (e.g., Vcc) to be applied to a reminder of the plurality of deintegrated source segments (i.e., 302₁-302₃) associated with a remainder of the plurality of sub-blocks (i.e., 305₁-305₃). To selectively activate another sub-block, the control logic can instead cause the ground voltage to be applied to the associated source segment (i.e., the source segment associated with the selected sub-block), while causing the positive supply voltage to be applied to the remaining source segments (i.e., the source segments associated with the unselected sub-blocks).

At operation 610, memory devices are programmed. For example, the control logic can program a plurality of select gate devices in a plurality of logical select gate layers 150 spanning the plurality of sub-blocks 305₀-305₃ and positioned at a drain-side (i.e., closer to bitline 304) of the first block 300 of the memory array 104 with a threshold voltage pattern. In the plurality of logical select gate layers 150 is disposed between a common bitline 304 shared by the plurality of sub-blocks and a plurality of data wordlines (i.e., WL₀-WL_N) that span the plurality of sub-blocks. In one embodiment, a number of logical select gate layers 150 in the block 300 is equal to a number of sub-blocks 305₀-305₃ in the block 300. In one embodiment, each of the plurality of logical select gate layers 150 comprises respective select gate devices associated with each of the plurality of sub-blocks 305₀-305₃, and the respective select gate devices in each layer are controlled by a respective one of a plurality of control signals (e.g., SGD0-SGD3). In one embodiment, the respective select gate devices in each of the plurality of logical select gate layers 150 are programmed with a threshold voltage pattern, wherein a first half of the respective select gate devices in each logical select gate layer 150 are programmed to a high threshold voltage and a second half of the respective select gate devices in each logical select gate layer 150 are programmed to a low threshold voltage, and wherein a first half of the select gate devices associated with each sub-block are programmed to the high threshold voltage and a second half of the select gate devices associated with each sub-block are programmed to the low threshold voltage. In one embodiment, the respective select gate devices in each of the plurality of logical select gate layers 150 are programmed with the threshold voltage pattern according to the sub-blocks that are selectively activated using the plurality of deintegrated source segments 302₁-302₃. For example, the application of specific source control signals (e.g., SRC0-SRC3) can select a particular source segment associated with a sub-block in which a corresponding one of the select gate devices that make up a given logical select gate layer 150 is to be programmed to a particular threshold voltage level according to the pattern.

FIGS. 7A-7G are diagrams illustrating a process flow for creating segmented source plates for sub-block definition in a memory device in accordance with some embodiments of the present disclosure. FIGS. 7A-7G represent a series of processing operations to be performed in the formation of the structure of a memory array including one or blocks with segmented source plates, as illustrated in FIG. 3 and in FIG. 4. The processing operations illustrated in FIGS. 7A-7G can be part of a manufacturing process performed using semiconductor fabrication equipment. In one embodiment, the memory device is formed from multiple discreet wafers, each including separate components, that are later electrically connected and packaged together to form the memory device, such as memory device 130 including some number of memory blocks 300. For example, a CMOS wafer may be fabricated separately to include signal drivers, control logic, decoding circuitry, registers, I/O circuitry and other components, separate from the memory array 104 itself.

FIG. 7A illustrates the fabrication of a separate memory wafer 700 including a memory array, which may be representative of memory array 104. In one embodiment, the memory wafer can include a number of horizontal layers (e.g., alternating oxide and nitride deposition layers) formed on a substrate 702 (e.g., silicon), with a number of array pillars 704 and through array vias 706 extending through the horizontal layers to the substrate 702. The array pillars 704 can be used to form memory cells at the intersections with the different horizontal layers and can further define one or more sub-blocks of a block of the array. In one embodiment, the memory wafer 700 further includes a number of stopping layers 710, 712 implanted throughout which can be used during subsequent processing steps, as described in more detail below. For example, the memory array wafer 700 can be thinned (e.g., via a planar process) up to the stopping layer 710 to remove excess portions of the substrate. Stopping layers 710, 712, can be formed from polysilicon, for example, which is selective to either oxide or nitride. Stopping layer 710 can further include a portion of the substrate silicon properly implanted at a certain depth, in order to generate selectivity (i.e., native silicon vs implanted silicon) during the silicon thinning process.

In FIG. 7B, the memory array wafer 700 has been inverted and the substrate layer fully removed. In FIG. 7B, additional portions of the memory array wafer 700 are illustrated including a first set of array pillars 704 that form a first block, and a second set of array pillars 714 that form a second block. Removal of the silicon substrate layer exposes portions of the array pillars 704 and 714, as well as the through array via 706. In one embodiment, prior to full removal of the substrate, the substrate layer can be thinned down (e.g., to approximately 300 nanometers). For example, the substrate layer may be etched away down to the stopping layer 710, which can be removed subsequently.

In FIG. 7C, a number of horizontal layers at the exposed portions of the array pillars 704 and 714, and the through array via 706 are removed. This can include all of the horizontal layers down to the stopping layer 712, which can be removed subsequently. For example, the topmost layers can be removed until the channel polysilicon is exposed to enable electrical connection with source polysilicon, which will be deposited subsequently.

In FIG. 7D, a source layer 720 is applied across the entire exposed portion of the memory array wafer 700. The source layer 720 covers the exposed portions of the array pillars 704 and 714, and the through array via 706. In one embodiment, the source layer 720 includes undoped polysilicon that is applied using a deposition process. The source layer 720 may be activated using a low temperature process. In one embodiment, source layer 720 is a relatively thin layer of polysilicon, which has high resistivity. In order to make source layer 720 adequately conductive, it can be activated using low temp processed, such as laser annealing.

In FIG. 7E, a conductive layer 722 is applied to the memory array wafer 700 above the source layer 720. Since the source layer 720 has a relatively high resistivity, the conductive layer 722 can reduce the sheet resistance and improve the conductivity of the source layer 720. The conductive layer 722 can be applied using a deposition process and, depending on the embodiment, the conductive layer 722 can be formed from Tungsten Silicide, Nickel Cobalt, or some other conductive material. The addition of conductive layer 722 is optional and may not be necessary in all implementations of the conductivity of the polysilicon source layer 720 is adequate.

In FIG. 7F, a masking process is performed to create the segmented source plate for sub-block definition in the memory array wafer 700. In one embodiment, a masking material is applied to the conductive layer 722 and source layer 720 in specific regions to define a number of sub-blocks. For example, masking material 730 can be applied to a first subset of the array pillars 704 and masking material 732 can be applied to a second subset of the array pillars 704. Similarly, masking material 734 can be applied to a first subset of the array pillars 714 and masking material 736 can be applied to a second subset of the array pillars 714. Each subset of array pillars can be part of a respective sub-block. It should be noted that the number of array pillars illustrated in each subset in FIG. 7F is merely exemplary and that the number of array pillars may vary in practice. For example the number of array pillars in each sub-block may be equal. In one embodiment, each sub-block may include some other number of array pillars. Once the respective sub-blocks are masked off with masking material, the conductive layer 722 and source layer 720 material can be removed from the non-masked areas. The removal of the conductive layer 722 and source layer 720 creates the source plate segments, which may be representative of deintegrated source segments 302₀-302₃, for example.

In FIG. 7G, the masking material is removed and an oxide layer 738 is deposited on memory array wafer 700. Further, conductive contacts 740, 742, 744, and 746 are created through the oxide layer 738 to allow for connection of the source plate segments to a metal layer to be subsequently formed. In addition, conductive contact 748 is created through oxide layer 738 to allow for connection of through array via 706 to the metal layer. The metal layer is coupled to the through array via 706 and can be used to transmit a plurality of source control signals (e.g., from the drivers and control signals on a later connected CMOS wafer) to the deintegrated source segments to selectively activate the respective sub-blocks.

The resulting physically segmented source segments, where a separate segment is associated with each sub-block, can be used in connection with the non-segregated logical select gate layers at a drain-side of the sub-blocks, as described above. Since the select gate devices in the logical select gate layers need not be physically segregated, a cut or slit between sub-blocks is not required at the drain-side of the memory array. Similarly, when a segmented source plate is utilized, the select gate devices at the source-side of the memory array also need not be physically segregated. As a result the spacing between the sub-blocks can be reduced, leading to a decreased width of each block. In other embodiments, the process illustrated in FIGS. 7A-7G can be repeated as many times as necessary to form the entirety of the memory array 104. In addition, although the formation of only four deintegrated source segments associated with four sub-blocks is illustrated, it should be understood that any number of source segments can be formed using the same processing techniques.

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) that includes, is coupled to, or utilizes a memory sub-system (e.g., the memory sub-system 110 of FIG. 1) or can be used to perform the operations of a controller (e.g., to execute an operating system to perform operations corresponding to the local media controller 135 of FIG. 1). 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.

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.

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 806 (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.

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 826 for performing the operations and steps discussed herein. The computer system 800 can further include a network interface device 808 to communicate over the network 820.

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 826 or software embodying any one or more of the methodologies or functions described herein. The instructions 826 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.

In one embodiment, the instructions 826 include instructions to implement functionality corresponding to the local media controller 135 of FIG. 1). 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 present 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.

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.

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 present 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.

The present 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.

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 present 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.

The present 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 present 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 components, etc.

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.

Claims

1. A method of forming a memory device comprising: forming a memory array comprising a plurality of memory cells arranged in a plurality of memory strings along a plurality of memory array pillars, wherein respective subsets of the memory array pillars correspond to respective sub-blocks of a block of the memory array; andforming a plurality of deintegrated source segments adjacent to the memory array, wherein the source segments of the plurality of deintegrated source segments are associated with respective sub-blocks and are physically segregated from one another.

2. The method of claim 1, further comprising: forming an electrical connection between each of the plurality of deintegrated source segments of the block to one or more corresponding source segments in each other block of a plurality blocks of the memory array.

3. The method of claim 1, wherein forming the memory array comprises: forming a substrate;forming a plurality of horizontal layers on the substrate; andforming the plurality of memory array pillars extending vertically through the plurality of horizontal layers, wherein each intersection of one of the plurality of horizontal layers and one of the plurality of memory array pillars comprises one of the plurality of memory cells in the memory array.

4. The method of claim 3, wherein forming the memory array further comprises: forming a through array via extending vertically through the plurality of horizontal layers.

5. The method of claim 4, further comprising: forming a plurality of conductive contacts between the plurality of deintegrated source segments and a metal layer disposed adjacent to the memory array, wherein the metal layer is further coupled to the through array via to transmit a plurality of source control signals to the plurality of deintegrated source segments to selectively activate the respective sub-blocks.

6. The method of claim 1, wherein forming the plurality of deintegrated source segments comprises: forming a source layer adjacent to the memory array, wherein the source layer is adjacent to exposed ends of the plurality of memory array pillars; andforming a conductive layer adjacent to the source layer.

7. The method of claim 6, wherein forming the plurality of deintegrated source segments comprises: applying a plurality of masking layer segments to the memory array adjacent to the conductive layer, the plurality of masking layer segments corresponding to the respective sub-blocks; andremoving the source layer and the conductive layer from areas of the memory array disposed between the plurality of masking layer segments to form the plurality of deintegrated source segments.

8. The method of claim 1, further comprising: forming a number of logical select gate layers positioned at a drain-side of the block, wherein the number of logical select gate layers are to selectively activate the respective sub-blocks responsive to received control signals.

9. A memory device comprising: a memory array comprising a plurality of memory cells arranged in a plurality of memory strings along a plurality of memory array pillars, wherein respective subsets of the memory array pillars correspond to respective sub-blocks of a block of the memory array; anda plurality of deintegrated source segments adjacent to the memory array, wherein the source segments of the plurality of deintegrated source segments are associated with respective sub-blocks and are physically segregated from one another.

10. The memory device of claim 9, wherein each of the plurality of deintegrated source segments of the block is electrically connected to one or more corresponding source segments in each other block of a plurality blocks of the memory array.

11. The memory device of claim 9, wherein the memory array comprises: a substrate; anda plurality of horizontal layers formed on the substrate, wherein the plurality of memory array pillars extend vertically through the plurality of horizontal layers, wherein each intersection of one of the plurality of horizontal layers and one of the plurality of memory array pillars comprises one of the plurality of memory cells in the memory array.

12. The memory device of claim 11, wherein the memory array further comprises: a through array via extending vertically through the plurality of horizontal layers.

13. The memory device of claim 12, further comprising: a plurality of conductive contacts between the plurality of deintegrated source segments and a metal layer disposed adjacent to the memory array, wherein the metal layer is further coupled to the through array via to transmit a plurality of source control signals to the plurality of deintegrated source segments to selectively activate the respective sub-blocks.

14. The memory device of claim 9, further comprising: a number of logical select gate layers positioned at a drain-side of the block, wherein the number of logical select gate layers are to selectively activate the respective sub-blocks responsive to received control signals.

15. A memory sub-system comprising: a memory sub-system controller; anda memory device coupled to the memory sub-system controller, the memory device comprising: a memory array comprising a plurality of memory cells arranged in a plurality of memory strings along a plurality of memory array pillars, wherein respective subsets of the memory array pillars correspond to respective sub-blocks of a block of the memory array; anda plurality of deintegrated source segments adjacent to the memory array, wherein the source segments of the plurality of deintegrated source segments are associated with respective sub-blocks and are physically segregated from one another.

16. The memory sub-system of claim 15, wherein each of the plurality of deintegrated source segments of the block is electrically connected to one or more corresponding source segments in each other block of a plurality blocks of the memory array.

17. The memory sub-system of claim 15, wherein the memory array comprises: a substrate; anda plurality of horizontal layers formed on the substrate, wherein the plurality of memory array pillars extend vertically through the plurality of horizontal layers, wherein each intersection of one of the plurality of horizontal layers and one of the plurality of memory array pillars comprises one of the plurality of memory cells in the memory array.

18. The memory sub-system of claim 17, wherein the memory array further comprises: a through array via extending vertically through the plurality of horizontal layers.

19. The memory sub-system of claim 18, wherein the memory device further comprises: a plurality of conductive contacts between the plurality of deintegrated source segments and a metal layer disposed adjacent to the memory array, wherein the metal layer is further coupled to the through array via to transmit a plurality of source control signals to the plurality of deintegrated source segments to selectively activate the respective sub-blocks.

20. The memory sub-system of claim 15, wherein the memory device further comprises: a number of logical select gate layers positioned at a drain-side of the block, wherein the number of logical select gate layers are to selectively activate the respective sub-blocks responsive to received control signals.