Patent Application
20230380159
Embodiments disclosed herein pertain to memory arrays comprising strings of memory cells and to methods used in forming a memory array comprising strings of memory cells.
Memory is one type of integrated circuitry and is used in computer systems for storing data. Memory may be fabricated in one or more arrays of individual memory cells. Memory cells may be written to, or read from, using digitlines (which may also be referred to as bitlines, data lines, or sense lines) and access lines (which may also be referred to as wordlines). The sense lines may conductively interconnect memory cells along columns of the array, and the access lines may conductively interconnect memory cells along rows of the array. Each memory cell may be uniquely addressed through the combination of a sense line and an access line.
Memory cells may be volatile, semi-volatile, or non-volatile. Non-volatile memory cells can store data for extended periods of time in the absence of power. Non-volatile memory is conventionally specified to be memory having a retention time of at least about 10 years. Volatile memory dissipates and is therefore refreshed/rewritten to maintain data storage. Volatile memory may have a retention time of milliseconds or less. Regardless, memory cells are configured to retain or store memory in at least two different selectable states. In a binary system, the states are considered as either a “0” or a “1”. In other systems, at least some individual memory cells may be configured to store more than two levels or states of information.
A field effect transistor is one type of electronic component that may be used in a memory cell. These transistors comprise a pair of conductive source/drain regions having a semiconductive channel region there-between. A conductive gate is adjacent the channel region and separated there-from by a thin gate insulator. Application of a suitable voltage to the gate allows current to flow from one of the source/drain regions to the other through the channel region. When the voltage is removed from the gate, current is largely prevented from flowing through the channel region. Field effect transistors may also include additional structure, for example a reversibly programmable charge-storage region as part of the gate construction between the gate insulator and the conductive gate.
Flash memory is one type of memory and has numerous uses in modern computers and devices. For instance, modern personal computers may have BIOS stored on a flash memory chip. As another example, it is becoming increasingly common for computers and other devices to utilize flash memory in solid state drives to replace conventional hard drives. As yet another example, flash memory is popular in wireless electronic devices because it enables manufacturers to support new communication protocols as they become standardized, and to provide the ability to remotely upgrade the devices for enhanced features.
Memory arrays may be arranged in memory pages, memory blocks and partial blocks (e.g., sub-blocks), and memory planes, for example as shown and described in any of U.S. Patent Application Publication Nos. 2015/0228651, 2016/0267984, and 2017/0140833. The memory blocks may at least in part define longitudinal outlines of individual wordlines in individual wordline tiers of vertically-stacked memory cells. Connections to these wordlines may occur in a so-called “stair-step structure” at an end or edge of an array of the vertically-stacked memory cells. The stair-step structure includes individual “stairs” (alternately termed “steps” or “stair-steps”) that define contact regions of the individual wordlines upon which elevationally-extending conductive vias contact to provide electrical access to the wordlines.
Embodiments of the invention encompass methods used in forming a memory array, for example an array of NAND or other memory cells that may have at least some peripheral control circuitry under the array (e.g., CMOS-under-array). Embodiments of the invention encompass so-called “gate-last” or “replacement-gate” processing, so-called “gate-first” processing, and other processing whether existing or future-developed independent of when transistor gates are formed. Embodiments of the invention also encompass integrated circuitry comprising a memory array comprising strings of memory cells (e.g., NAND architecture) independent of method of manufacture. First example method embodiments are described with reference to
A conductor tier 16 comprising conductor material 17 has been formed above substrate 11. Conductor material 17 as shown comprises upper conductor material 43 directly above and directly electrically coupled to (e.g., directly against) lower conductor material 44 of different composition from upper conductor material 43. In one embodiment, upper conductor material 43 comprises conductively-doped semiconductive material (e.g., n-type-doped or p-type-doped silicon). In one embodiment, lower conductor material 44 comprises metal material (e.g., a metal silicide such as WSix). Conductor tier 16 may comprise part of control circuitry (e.g., peripheral-under-array circuitry and/or a common source line or plate) used to control read and write access to the transistors and/or memory cells that will be formed within array 12. Conductor tier 16 may be considered as having a top surface 70. Top surface 70 comprises conductor material 17 (e.g., upper conductor material 43). Lower conductor material 44 may be considered as having a top surface 71. Either or both of surfaces 70 and 71 may be planar.
A lower portion 18L of a stack 18* has been formed above substrate 11 and conductor tier 16 (an * being used as a suffix to be inclusive of all such same-numerically-designated components that may or may not have other suffixes). Stack 18* will comprise vertically-alternating conductive tiers 22* and insulative tiers 20*, with material of tiers 22* being of different composition from material of tiers 20*. Stack 18* comprises laterally-spaced memory-block regions 58 that will comprise laterally-spaced memory blocks 58 in a finished circuitry construction. In this document, unless otherwise indicated, “block” is generic to include “sub-block”. Memory-block regions 58 and resultant memory blocks 58 (not yet shown) may be considered as being longitudinally elongated and oriented, for example along a direction 55. Memory-block regions 58 may not be discernable at this point of processing.
Conductive tiers 22* (alternately referred to as first tiers) may not comprise conducting material and insulative tiers 20* (alternately referred to as second tiers) may not comprise insulative material or be insulative at this point in processing in conjunction with the hereby initially-described example method embodiment which is “gate-last” or “replacement-gate”. In one embodiment, lower portion 18L comprises a lowest tier 20z of second tiers 20* directly above (e.g., directly against) conductor material 17. Example lowest second tier 20z is insulative and may be sacrificial (e.g., comprising material 62, for example silicon dioxide and/or silicon nitride). A next-lowest second tier 20x of second tiers 20* is directly above lowest second tier 20z and may be sacrificial (e.g., comprising material 63, for example silicon dioxide and/or silicon nitride). A lowest tier 22z of first tiers 22* comprising sacrificial material 77 (e.g., polysilicon or silicon nitride) is vertically between lowest second tier 20z and next-lowest second tier 20x. In one embodiment, lower portion 18L comprises a conducting tier 21 comprising conducting material 47 (e.g., conductively-doped polysilicon) that is directly above next-lowest second tier 20x. Example lower portion 18L comprises an upper second tier 20w (e.g., a next-next lowest second tier) comprising insulative material 24 (e.g., silicon dioxide). Additional tiers may be present. For example, one or more additional tiers may be above tier 20w (tier 20w thereby not being the uppermost tier in portion 18L, and not shown), between tier 20w and conducting tier 21 (not shown), and/or below tier 22z (other than 20z not being shown). In one embodiment, lower portion 18L at least as initially formed comprises multiple first/conductive tiers (e.g., 22z and 21) tiers and multiple second/insulative tiers (e.g., 20z, 20x, 20w). In one embodiment and as shown, upper second tier 20w is the uppermost second tier 20* in lower portion 18L.
Referring to
Sacrificial plugs 75 may be formed, by way of example, by etching openings into conductor material 17, filling said openings with plug material and planarizing the plug material back. The composition of sacrificial plugs 75 may be conductive, semiconductive, and/or insulative whereby sacrificial plugs 75 are overall one of conductive, semiconductive, or insulative. In at least one embodiment, the composition of sacrificial plugs 75 includes one or more of W, borophosphosilicate glass (BPSG), and/or AlOx (e.g., Al2O3). Sacrificial plugs 5 may be formed to have a portion (e.g., bottom surface 92) directly against top surface 71 of the metal material 44.
Some embodiments of plugs 75 are diagrammatically depicted in
Referring to
Referring next to
Referring next to
Referring next to
Referring next to
Referring to
Channel openings 25 have been etched through first and second conductive tiers (22*/20*) of stack 18* (18U and 18L) to sacrificial plugs 75. Channel openings 25 may by somewhat laterally mis-aligned relative to sacrificial plugs 75, for example as shown.
Transistor channel material may be formed in the individual channel openings elevationally along the insulative tiers and the conductive tiers, thus comprising individual channel-material strings, which are directly electrically coupled with conductive material in the conductor tier. Individual memory cells of the example memory array being formed may comprise a gate region (e.g., a control-gate region) and a memory structure laterally-between the gate region and the channel material. In one such embodiment, the memory structure is formed to comprise a charge-blocking region, storage material (e.g., charge-storage material), and an insulative charge-passage material. The storage material (e.g., floating gate material such as doped or undoped silicon or charge-trapping material such as silicon nitride, metal dots, etc.) of the individual memory cells is elevationally along individual of the charge-blocking regions. The insulative charge-passage material (e.g., a band gap-engineered structure having nitrogen-containing material [e.g., silicon nitride] sandwiched between two insulator oxides [e.g., silicon dioxide]) is laterally-between the channel material and the storage material.
Referring to
Channel material 36 as a channel-material string 53 of a channel-material-string construction 78 has also been formed in channel openings 25 elevationally along insulative tiers 20 and conductive tiers 22. Accordingly, and as one example as shown, a channel-material-string construction 78 is in individual channel openings 25 and extends to be directly against lower conductor material 44.
Materials 30, 32, 34, and 36 are collectively shown as and only designated as material 37 in some figures due to scale. Example channel materials 36 include appropriately-doped crystalline semiconductor material, such as one or more silicon, germanium, and so-called III/V semiconductor materials (e.g., GaAs, InP, GaP, and GaN). Example thickness for each of materials 30, 32, 34, and 36 is 25 to 100 Angstroms. Punch etching may be conducted to remove materials 30, 32, and 34 from the bases of channel openings 25 (not shown) to expose conductor tier 16 such that channel material 36 is directly against conductor material 17 of conductor tier 16. Such punch etching may occur separately with respect to each of materials 30, 32, and 34 (as shown) or may occur with respect to only some (not shown).
In one embodiment and as shown, individual channel-material strings 53 of channel-material-string constructions 78 have been formed to comprise external jog surface 112 in a vertical cross-section (e.g., that of
Referring to
Referring to
Referring to
Referring to
A thin insulative liner (e.g., Al2O3 and not shown) may be formed before forming conducting material 48. Approximate locations of some transistors and/or some memory cells 56 are indicated with a bracket or with dashed outlines, with transistors and/or memory cells 56 being essentially ring-like or annular in the depicted example. Alternately, transistors and/or memory cells 56 may not be completely encircling relative to individual channel openings 25 such that each channel opening 25 may have two or more elevationally-extending strings 49 (e.g., multiple transistors and/or memory cells about individual channel openings in individual conductive tiers with perhaps multiple wordlines per channel opening in individual conductive tiers, and not shown). Conducting material 48 may be considered as having terminal ends 50 corresponding to control-gate regions 52 of individual transistors and/or memory cells 56. Control-gate regions 52 in the depicted embodiment comprise individual portions of individual conductive lines 29. Materials 30, 32, and 34 may be considered as a memory structure 65 that is laterally between control-gate region 52 and channel material 36. In one embodiment and as shown with respect to the example “gate-last” processing, conducting material 48 of conductive tiers 22* is formed after forming openings 25 and/or trenches 40. Alternately, the conducting material of the conductive tiers may be formed before forming channel openings 25 and/or trenches 40 (not shown), for example with respect to “gate-first” processing.
A charge-blocking region (e.g., charge-blocking material 30) is between storage material 32 and individual control-gate regions 52. A charge block may have the following functions in a memory cell: In a program mode, the charge block may prevent charge carriers from passing out of the storage material (e.g., floating-gate material, charge-trapping material, etc.) toward the control gate, and in an erase mode the charge block may prevent charge carriers from flowing into the storage material from the control gate. Accordingly, a charge block may function to block charge migration between the control-gate region and the storage material of individual memory cells. An example charge-blocking region as shown comprises insulator material 30. By way of further examples, a charge-blocking region may comprise a laterally (e.g., radially) outer portion of the storage material (e.g., material 32) where such storage material is insulative (e.g., in the absence of any different-composition material between an insulative storage material 32 and conducting material 48). Regardless, as an additional example, an interface of a storage material and conductive material of a control gate may be sufficient to function as a charge-blocking region in the absence of any separate-composition-insulator material 30. Further, an interface of conducting material 48 with material 30 (when present) in combination with insulator material 30 may together function as a charge-blocking region, and as alternately or additionally may a laterally-outer region of an insulative storage material (e.g., a silicon nitride material 32). An example material 30 is one or more of silicon hafnium oxide and silicon dioxide.
Intervening material 57 has been formed in trenches 40 and thereby laterally-between and longitudinally-along immediately-laterally-adjacent memory blocks 58. Intervening material 57 may provide lateral electrical isolation (insulation) between immediately-laterally-adjacent memory blocks. Such may include one or more of insulative, semiconductive, and conducting materials and, regardless, may facilitate conductive tiers 22* from shorting relative one another in a finished circuitry construction. Example insulative materials are one or more of SiO2, Si3N4, and Al2O3. Intervening material 57 may include through array vias (not shown).
Channel-material-string constructions 78 may comprise sidewalls surfaces 79 that are straight through alternating insulative 20U and conductive 22U tiers of the memory array, and above external jog surface 112 which is above top surface 70 of conductor tier 16. Internal jog surface 110 is within conductor tier 16 and below alternating insulative 20U and conductive 22U tiers in the vertical cross-section. In accordance, with example implementations, part 116 and/or part 114 may be horizontal including exactly horizontal (see, e.g.,
In one embodiment, individual ones of channel-material strings 53, in a vertical cross-section, comprise external jog surface 112 that is above conductor tier 16, with individual ones of channel-material strings 53, in the vertical cross-section above conductor tier 16 being wider (W1) above external jog surface 112 than below external jog surface 112 (W2).
A motivation for the invention was to improve reliability of direct electrical connection between the channel-material-string constructions 78 and the conductor tier 16.
Any other attribute(s) or aspect(s) as shown and/or described herein with respect to other embodiments may be used in the embodiments shown and described with reference to the above embodiments.
Alternate embodiment constructions may result from method embodiments described above, or otherwise. Regardless, embodiments of the invention encompass memory arrays independent of method of manufacture. Nevertheless, such memory arrays may have any of the attributes as described herein in method embodiments. Likewise, the above-described method embodiments may incorporate, form, and/or have any of the attributes described with respect to device embodiments.
In one embodiment, a memory array (e.g., 12) comprises strings (e.g., 49) of memory cells (e.g., 56). The memory array comprises laterally-spaced memory blocks (e.g., 58) that individually comprise a vertical stack (e.g., 18*) comprising alternating insulative tiers (e.g., 20*) and conductive tiers (e.g., 22*) directly above a conductor tier (e.g., 16). Channel-material strings (e.g., 53) of memory cells (e.g., 56) extend through the insulative tiers and the conductive tiers. The channel material (e.g., 36) of the channel-material strings directly electrically couples to conductor material (e.g., 17) of the conductor tier. Individual ones of the channel-material strings in a vertical cross-section comprise an external jog surface (e.g., 112) that is above the conductor tier and an internal jog surface (e.g., 110) that is in the conductor tier. Any other attribute(s) or aspect(s) as shown and/or described herein with respect to other embodiments may be used.
In one embodiment, a memory array (e.g., 12) comprises strings (e.g., 49) of memory cells (e.g., 56). The memory array comprises laterally-spaced memory blocks (e.g., 58) that individually comprises a vertical stack (e.g., 18*) comprising alternating insulative tiers (e.g., 20*) and conductive tiers (e.g., 22*) directly above a conductor tier (e.g., 16). Channel-material strings (e.g., 53) of memory cells (e.g., 56) extend through the insulative tiers and the conductive tiers. The channel material (e.g., 36) of the channel-material strings directly electrically couples to conductor material (e.g., 17) of the conductor tier. Individual ones of the channel-material strings in a vertical cross-section comprise an external jog surface (e.g., 112) that is above the conductor tier. The individual ones of the channel-material strings in the vertical cross-section and above the conductor tier are wider above the external jog surface than below the external jog surface. Any other attribute(s) or aspect(s) as shown and/or described herein with respect to other embodiments may be used.
The above processing(s) or construction(s) may be considered as being relative to an array of components formed as or within a single stack or single deck of such components above or as part of an underlying base substrate (albeit, the single stack/deck may have multiple tiers). Control and/or other peripheral circuitry for operating or accessing such components within an array may also be formed anywhere as part of the finished construction, and in some embodiments may be under the array (e.g., CMOS under-array). Regardless, one or more additional such stack(s)/deck(s) may be provided or fabricated above and/or below that shown in the figures or described above. Further, the array(s) of components may be the same or different relative one another in different stacks/decks and different stacks/decks may be of the same thickness or of different thicknesses relative one another. Intervening structure may be provided between immediately-vertically-adjacent stacks/decks (e.g., additional circuitry and/or dielectric layers). Also, different stacks/decks may be electrically coupled relative one another. The multiple stacks/decks may be fabricated separately and sequentially (e.g., one atop another), or two or more stacks/decks may be fabricated at essentially the same time.
The assemblies and structures discussed above may be used in integrated circuits/circuitry and may be incorporated into electronic systems. Such electronic systems may be used in, for example, memory modules, device drivers, power modules, communication modems, processor modules, and application-specific modules, and may include multilayer, multichip modules. The electronic systems may be any of a broad range of systems, such as, for example, cameras, wireless devices, displays, chip sets, set top boxes, games, lighting, vehicles, clocks, televisions, cell phones, personal computers, automobiles, industrial control systems, aircraft, etc.
In this document unless otherwise indicated, “elevational”, “higher”, “upper”, “lower”, “top”, “atop”, “bottom”, “above”, “below”, “under”, “beneath”, “up”, and “down” are generally with reference to the vertical direction. “Horizontal” refers to a general direction (i.e., within 10 degrees) along a primary substrate surface and may be relative to which the substrate is processed during fabrication, and vertical is a direction generally orthogonal thereto. Reference to “exactly horizontal” is the direction along the primary substrate surface (i.e., no degrees there-from) and may be relative to which the substrate is processed during fabrication. Further, “vertical” and “horizontal” as used herein are generally perpendicular directions relative one another and independent of orientation of the substrate in three-dimensional space. Additionally, “elevationally-extending” and “extend(ing) elevationally” refer to a direction that is angled away by at least 45° from exactly horizontal. Further, “extend(ing) elevationally”, “elevationally-extending”, “extend(ing) horizontally”, “horizontally-extending” and the like with respect to a field effect transistor are with reference to orientation of the transistor's channel length along which current flows in operation between the source/drain regions. For bipolar junction transistors, “extend(ing) elevationally” “elevationally-extending”, “extend(ing) horizontally”, “horizontally-extending” and the like, are with reference to orientation of the base length along which current flows in operation between the emitter and collector. In some embodiments, any component, feature, and/or region that extends elevationally extends vertically or within 10° of vertical.
Further, “directly above”, “directly below”, and “directly under” require at least some lateral overlap (i.e., horizontally) of two stated regions/materials/components relative one another. Also, use of “above” not preceded by “directly” only requires that some portion of the stated region/material/component that is above the other be elevationally outward of the other (i.e., independent of whether there is any lateral overlap of the two stated regions/materials/components). Analogously, use of “below” and “under” not preceded by “directly” only requires that some portion of the stated region/material/component that is below/under the other be elevationally inward of the other (i.e., independent of whether there is any lateral overlap of the two stated regions/materials/components).
Any of the materials, regions, and structures described herein may be homogenous or non-homogenous, and regardless may be continuous or discontinuous over any material which such overlie. Where one or more example composition(s) is/are provided for any material, that material may comprise, consist essentially of, or consist of such one or more composition(s). Further, unless otherwise stated, each material may be formed using any suitable existing or future-developed technique, with atomic layer deposition, chemical vapor deposition, physical vapor deposition, epitaxial growth, diffusion doping, and ion implanting being examples.
Additionally, “thickness” by itself (no preceding directional adjective) is defined as the mean straight-line distance through a given material or region perpendicularly from a closest surface of an immediately-adjacent material of different composition or of an immediately-adjacent region. Additionally, the various materials or regions described herein may be of substantially constant thickness or of variable thicknesses. If of variable thickness, thickness refers to average thickness unless otherwise indicated, and such material or region will have some minimum thickness and some maximum thickness due to the thickness being variable. As used herein, “different composition” only requires those portions of two stated materials or regions that may be directly against one another to be chemically and/or physically different, for example if such materials or regions are not homogenous. If the two stated materials or regions are not directly against one another, “different composition” only requires that those portions of the two stated materials or regions that are closest to one another be chemically and/or physically different if such materials or regions are not homogenous. In this document, a material, region, or structure is “directly against” another when there is at least some physical touching contact of the stated materials, regions, or structures relative one another. In contrast, “over”, “on”, “adjacent”, “along”, and “against” not preceded by “directly” encompass “directly against” as well as construction where intervening material(s), region(s), or structure(s) result(s) in no physical touching contact of the stated materials, regions, or structures relative one another.
Herein, regions-materials-components are “electrically coupled” relative one another if in normal operation electric current is capable of continuously flowing from one to the other and does so predominately by movement of subatomic positive and/or negative charges when such are sufficiently generated. Another electronic component may be between and electrically coupled to the regions-materials-components. In contrast, when regions-materials-components are referred to as being “directly electrically coupled”, no intervening electronic component (e.g., no diode, transistor, resistor, transducer, switch, fuse, etc.) is between the directly electrically coupled regions-materials-components.
Any use of “row” and “column” in this document is for convenience in distinguishing one series or orientation of features from another series or orientation of features and along which components have been or may be formed. “Row” and “column” are used synonymously with respect to any series of regions, components, and/or features independent of function. Regardless, the rows may be straight and/or curved and/or parallel and/or not parallel relative one another, as may be the columns. Further, the rows and columns may intersect relative one another at 90° or at one or more other angles (i.e., other than the straight angle).
The composition of any of the conductive/conductor/conducting materials herein may be conductive metal material and/or conductively-doped semiconductive/semiconductor/semiconducting material. “Metal material” is any one or combination of an elemental metal, any mixture or alloy of two or more elemental metals, and any one or more metallic compound(s).
Herein, any use of “selective” as to etch, etching, removing, removal, depositing, forming, and/or formation is such an act of one stated material relative to another stated material(s) so acted upon at a rate of at least 2:1 by volume. Further, any use of selectively depositing, selectively growing, or selectively forming is depositing, growing, or forming one material relative to another stated material or materials at a rate of at least 2:1 by volume for at least the first 75 Angstroms of depositing, growing, or forming.
Unless otherwise indicated, use of “or” herein encompasses either and both.
In some embodiments, a method used in forming a memory array comprising strings of memory cells comprises forming a conductor tier comprising conductor material on a substrate. The conductor tier has a top surface comprising the conductor material. The conductor tier comprises sacrificial plugs in locations where individual channel-material strings will be formed. The sacrificial plugs individually have a top surface that is at or below the top surface of the conductor tier and is of different composition from an upper portion of the conductor material. Laterally-spaced memory-block regions are formed that individually comprise a vertical stack comprising alternating first tiers and second tiers directly above the conductor tier. Material of the first tiers is of different composition from material of the second tiers. Channel openings are etched through the first tiers and the second tiers to the sacrificial plugs. The sacrificial plugs are removed and thereafter a channel-material string is formed in individual ones of the channel openings. The channel material of the channel-material string directly electrically couples to the conductor material in the conductor tier.
In some embodiments, a method used in forming a memory array comprising strings of memory cells comprises forming a conductor tier comprising conductor material on a substrate. The conductor material comprises upper conductor material directly above lower conductor material that is of different composition from the upper conductor material. The upper conductor material has a top surface. Sacrificial plugs are formed in the conductor tier in locations where individual channel-material strings will be formed. The sacrificial plugs are of different composition from the upper conductor material. The sacrificial plugs individually have a top surface that is at or below the top surface of the upper conductor material. The sacrificial plugs individually have a bottom surface that is at or above a top surface of the lower conductor material. Laterally-spaced memory-block regions are formed that individually comprise a vertical stack comprising alternating first tiers and second tiers directly above the conductor tier. Material of the first tiers is of different composition from material of the second tiers. Channel openings are etched through the first tiers and the second tiers to the sacrificial plugs. The sacrificial plugs are removed and thereafter a channel-material string is formed in individual ones of the channel openings and that extends into the conductor tier. The channel material of the channel-material string directly electrically couples to the conductor material in the conductor tier.
In some embodiments, a method used in forming a memory array comprising strings of memory cells comprises forming a conductor tier comprising conductor material on a substrate. The conductor tier has a top surface that comprises the conductor material. Sacrificial plugs are formed in locations where individual channel-material strings will be formed. The sacrificial plugs individually have a top surface that is at or below the top surface of the conductor tier and is of different composition from an upper portion of the conductor material. A lower portion of a stack is formed that will comprise vertically-alternating first tiers and second tiers directly above the conductor tier and the sacrificial plugs. The stack comprises laterally-spaced memory-block regions. Material of the first tiers is of different composition from material of the second tiers. A lowest of the first tiers comprises sacrificial material. The vertically-alternating first tiers and second tiers of an upper portion of the stack are formed directly above the lower portion and the sacrificial plugs. Channel openings are etched through the first tiers and the second tiers to the sacrificial plugs. The sacrificial plugs are removed through the channel openings. After removing the sacrificial plugs, a channel-material-string construction is formed in individual ones of the channel openings. Horizontally-elongated trenches are formed into the stack that are individually laterally-between immediately-laterally-adjacent of the memory-block regions. The trenches extend through the upper portion to the lowest first tier and expose the sacrificial material therein. The exposed sacrificial material is isotropically etched from the lowest first tier through the trenches. After the isotropic etching, conductive material is formed in the lowest first tier that directly electrically couples together the channel material of the channel-material-string construction and the conductor material of the conductor tier.
In some embodiments, a memory array comprises strings of memory cells. The memory array comprises laterally-spaced memory blocks that individually comprise a vertical stack comprising alternating insulative tiers and conductive tiers directly above a conductor tier. Channel-material strings of memory cells extend through the insulative tiers and the conductive tiers. The channel material of the channel-material strings directly electrically couples to conductor material of the conductor tier. Individual ones of the channel-material strings in a vertical cross-section comprise an external jog surface that is above the conductor tier and an internal jog surface that is in the conductor tier.
In some embodiments, a memory array comprises strings of memory cells. The memory array comprises laterally-spaced memory blocks that individually comprise a vertical stack comprising alternating insulative tiers and conductive tiers directly above a conductor tier. Channel-material strings of memory cells extend through the insulative tiers and the conductive tiers. The channel material of the channel-material strings directly electrically couples to conductor material of the conductor tier. Individual ones of the channel-material strings in a vertical cross-section comprise an external jog surface that is above the conductor tier. The individual ones of the channel-material strings in the vertical cross-section and above the conductor tier are wider above the external jog surface than below the external jog surface.
In compliance with the statute, the subject matter disclosed herein has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the claims are not limited to the specific features shown and described, since the means herein disclosed comprise example embodiments. The claims are thus to be afforded full scope as literally worded, and to be appropriately interpreted in accordance with the doctrine of equivalents.
