Patent Publication Number: US-11665894-B2

Title: Microelectronic devices, memory devices, and electronic systems

Description:
TECHNICAL FIELD 
     The disclosure, in various embodiments, relates generally to the field of microelectronic device design and fabrication. More specifically, the disclosure relates to methods of forming microelectronic devices, and to related microelectronic devices, memory devices, and electronic systems. 
     BACKGROUND 
     Microelectronic device designers often desire to increase the level of integration or density of features within a microelectronic device by reducing the dimensions of the individual features and by reducing the separation distance between neighboring features. In addition, microelectronic device designers often seek to design architectures that are not only compact, but offer performance advantages, as well as simplified designs. 
     One example of a microelectronic device is a memory device. Memory devices are generally provided as internal integrated circuits in computers or other electronic devices. There are many types of memory devices including, but not limited to, non-volatile memory devices (e.g., NAND Flash memory devices). One way of increasing memory density in non-volatile memory devices is to utilize vertical memory array (also referred to as a “three-dimensional (3D) memory array”) architectures. A conventional vertical memory array includes strings of memory cells vertically extending through one or more stack structures including tiers of conductive material and insulative material. Each string of memory cells may include at least one select device coupled thereto. Such a configuration permits a greater number of switching devices (e.g., transistors) to be located in a unit of die area (i.e., length and width of active surface consumed) by building the array upwards (e.g., vertically) on a die, as compared to structures with conventional planar (e.g., two-dimensional) arrangements of transistors. 
     Vertical memory array architectures generally include electrical connections between the conductive material of the tiers of the stack structure(s) of the memory device and control logic devices (e.g., string drivers) so that the memory cells of the vertical memory array can be uniquely selected for writing, reading, or erasing operations. One method of forming such an electrical connection includes forming so-called “staircase” (or “stair step”) structures at edges (e.g., horizontal ends) of the tiers of the stack structure(s) of the memory device. The staircase structure includes individual “steps” defining contact regions for the conductive material of the tiers, upon which conductive contact structures can be positioned to provide electrical access to the conductive material. In turn, conductive routing structures can be employed to couple the conductive contact structures to the control logic devices. However, conventional staircase structure fabrication techniques can segment the conductive material of an individual tier in a manner resulting in discontinuous conductive paths through the tier that can require the use of multiple (e.g., more than one) switching devices (e.g., transistors) of at least one string driver to drive voltages completely across the tier and/or in opposing directions across the tier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a simplified, partial perspective view of a microelectronic device structure at a processing stage of a method forming a microelectronic device, in accordance with embodiments of the disclosure.  FIG.  1 B  is a simplified, longitudinal cross-sectional view of a portion A (identified with dashed lines in  FIG.  1 A ) of the microelectronic device structure at the processing stage of  FIG.  1 A .  FIG.  1 C  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure at the processing stage of  FIGS.  1 A and  1 B  about a dashed line B-B shown in  FIG.  1 B . 
         FIG.  2 A  is a simplified, longitudinal cross-sectional view of the portion A of the microelectronic device structure shown in  FIGS.  1 A through  1 C  at another processing stage of the method forming the microelectronic device following the processing stage of  FIGS.  1 A through  1 C .  FIG.  2 B  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure at the processing stage of  FIG.  2 A  about the dashed line B-B shown in  FIG.  2 A . 
         FIG.  3 A  is a simplified, longitudinal cross-sectional view of the portion A of the microelectronic device structure shown in  FIGS.  1 A through  1 C  at another processing stage of the method forming the microelectronic device following the processing stage of  FIGS.  2 A and  2 B .  FIG.  3 B  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure at the processing stage of  FIG.  3 A  about the dashed line B-B shown in  FIG.  3 A . 
         FIG.  4 A  is a simplified, partial perspective view of a microelectronic device structure shown in  FIGS.  1 A through  1 C  at another processing stage of the method forming the microelectronic device following the processing stage of  FIGS.  3 A and  3 B .  FIG.  4 B  is a simplified, longitudinal cross-sectional view of the portion A of the microelectronic device structure shown at the processing stage of  FIG.  4 A .  FIG.  4 C  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure at the processing stage of  FIGS.  4 A and  4 B  about a dashed line B-B shown in  FIG.  4 B . 
         FIG.  5 A  is a simplified, longitudinal cross-sectional view of the portion A of the microelectronic device structure shown in  FIGS.  1 A through  1 C  at another processing stage of the method forming the microelectronic device following the processing stage of  FIGS.  4 A through  4 C .  FIG.  5 B  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure at the processing stage of  FIG.  5 A  about the dashed line B-B shown in  FIG.  5 A . 
         FIG.  6 A  is a simplified, longitudinal cross-sectional view of the portion A of the microelectronic device structure shown in  FIGS.  1 A through  1 C  at another processing stage of the method forming the microelectronic device following the processing stage of  FIGS.  5 A and  5 B .  FIG.  6 B  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure at the processing stage of  FIG.  6 A  about the dashed line B-B shown in  FIG.  6 A . 
         FIG.  7    is a simplified partial cutaway perspective view of a microelectronic device, in accordance with embodiments of the disclosure. 
         FIG.  8    is a schematic block diagram illustrating an electronic system, in accordance with embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description provides specific details, such as material compositions, shapes, and sizes, in order to provide a thorough description of embodiments of the disclosure. However, a person of ordinary skill in the art would understand that the embodiments of the disclosure may be practiced without employing these specific details. Indeed, the embodiments of the disclosure may be practiced in conjunction with conventional microelectronic device fabrication techniques employed in the industry. In addition, the description provided below does not form a complete process flow for manufacturing a microelectronic device (e.g., a memory device). The structures described below do not form a complete microelectronic device. Only those process acts and structures necessary to understand the embodiments of the disclosure are described in detail below. Additional acts to form a complete microelectronic device from the structures may be performed by conventional fabrication techniques. 
     Drawings presented herein are for illustrative purposes only, and are not meant to be actual views of any particular material, component, structure, device, or system. Variations from the shapes depicted in the drawings as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein are not to be construed as being limited to the particular shapes or regions as illustrated, but include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as box-shaped may have rough and/or nonlinear features, and a region illustrated or described as round may include some rough and/or linear features. Moreover, sharp angles that are illustrated may be rounded, and vice versa. Thus, the regions illustrated in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of a region and do not limit the scope of the present claims. The drawings are not necessarily to scale. Additionally, elements common between figures may retain the same numerical designation. 
     As used herein, a “memory device” means and includes microelectronic devices exhibiting memory functionality, but not necessary limited to memory functionality. Stated another way, and by way of non-limiting example only, the term “memory device” includes not only conventional memory (e.g., conventional volatile memory, such as conventional dynamic random access memory (DRAM); conventional non-volatile memory, such as conventional NAND memory), but also includes an application specific integrated circuit (ASIC) (e.g., a system on a chip (SoC)), a microelectronic device combining logic and memory, and a graphics processing unit (GPU) incorporating memory. 
     As used herein, the term “configured” refers to a size, shape, material composition, orientation, and arrangement of one or more of at least one structure and at least one apparatus facilitating operation of one or more of the structure and the apparatus in a predetermined way. 
     As used herein, the terms “vertical,” “longitudinal,” “horizontal,” and “lateral” are in reference to a major plane of a structure and are not necessarily defined by earth&#39;s gravitational field. A “horizontal” or “lateral” direction is a direction that is substantially parallel to the major plane of the structure, while a “vertical” or “longitudinal” direction is a direction that is substantially perpendicular to the major plane of the structure. The major plane of the structure is defined by a surface of the structure having a relatively large area compared to other surfaces of the structure. With reference to the figures, a “horizontal” or “lateral” direction may be perpendicular to an indicated “Z” axis, and may be parallel to an indicated “X” axis and/or parallel to an indicated “Y” axis; and a “vertical” or “longitudinal” direction may be parallel to an indicated “Z” axis, may be perpendicular to an indicated “X” axis, and may be perpendicular to an indicated “Y” axis. 
     As used herein, features (e.g., regions, structures, devices) described as “neighboring” one another means and includes features of the disclosed identity (or identities) that are located most proximate (e.g., closest to) one another. Additional features (e.g., additional regions, additional structures, additional devices) not matching the disclosed identity (or identities) of the “neighboring” features may be disposed between the “neighboring” features. Put another way, the “neighboring” features may be positioned directly adjacent one another, such that no other feature intervenes between the “neighboring” features; or the “neighboring” features may be positioned indirectly adjacent one another, such that at least one feature having an identity other than that associated with at least one the “neighboring” features is positioned between the “neighboring” features. Accordingly, features described as “vertically neighboring” one another means and includes features of the disclosed identity (or identities) that are located most vertically proximate (e.g., vertically closest to) one another. Moreover, features described as “horizontally neighboring” one another means and includes features of the disclosed identity (or identities) that are located most horizontally proximate (e.g., horizontally closest to) one another. 
     As used herein, spatially relative terms, such as “beneath,” “below,” “lower,” “bottom,” “above,” “upper,” “top,” “front,” “rear,” “left,” “right,” and the like, may be used for ease of description to describe one element&#39;s or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Unless otherwise specified, the spatially relative terms are intended to encompass different orientations of the materials in addition to the orientation depicted in the figures. For example, if materials in the figures are inverted, elements described as “below” or “beneath” or “under” or “on bottom of” other elements or features would then be oriented “above” or “on top of” the other elements or features. Thus, the term “below” can encompass both an orientation of above and below, depending on the context in which the term is used, which will be evident to one of ordinary skill in the art. The materials may be otherwise oriented (e.g., rotated 90 degrees, inverted, flipped) and the spatially relative descriptors used herein interpreted accordingly. 
     As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     As used herein, “and/or” includes any and all combinations of one or more of the associated listed items. 
     As used herein, the phrase “coupled to” refers to structures operatively connected with each other, such as electrically connected through a direct Ohmic connection or through an indirect connection (e.g., by way of another structure). 
     As used herein, the term “substantially” in reference to a given parameter, property, or condition means and includes to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a degree of variance, such as within acceptable tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0 percent met, at least 95.0 percent met, at least 99.0 percent met, at least 99.9 percent met, or even 100.0 percent met. 
     As used herein, “about” or “approximately” in reference to a numerical value for a particular parameter is inclusive of the numerical value and a degree of variance from the numerical value that one of ordinary skill in the art would understand is within acceptable tolerances for the particular parameter. For example, “about” or “approximately” in reference to a numerical value may include additional numerical values within a range of from 90.0 percent to 110.0 percent of the numerical value, such as within a range of from 95.0 percent to 105.0 percent of the numerical value, within a range of from 97.5 percent to 102.5 percent of the numerical value, within a range of from 99.0 percent to 101.0 percent of the numerical value, within a range of from 99.5 percent to 100.5 percent of the numerical value, or within a range of from 99.9 percent to 100.1 percent of the numerical value. 
     As used herein, “conductive material” means and includes electrically conductive material such as one or more of a metal (e.g., tungsten (W), titanium (Ti), molybdenum (Mo), niobium (Nb), vanadium (V), hafnium (Hf), tantalum (Ta), chromium (Cr), zirconium (Zr), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pa), platinum (Pt), copper (Cu), silver (Ag), gold (Au), aluminum (Al)), an alloy (e.g., a Co-based alloy, an Fe-based alloy, an Ni-based alloy, an Fe- and Ni-based alloy, a Co- and Ni-based alloy, an Fe- and Co-based alloy, a Co- and Ni- and Fe-based alloy, an Al-based alloy, a Cu-based alloy, a magnesium (Mg)-based alloy, a Ti-based alloy, a steel, a low-carbon steel, a stainless steel), a conductive metal-containing material (e.g., a conductive metal nitride, a conductive metal silicide, a conductive metal carbide, a conductive metal oxide), and a conductively doped semiconductor material (e.g., conductively-doped polysilicon, conductively-doped germanium (Ge), conductively-doped silicon germanium (SiGe)). In addition, a “conductive structure” means and includes a structure formed of and including conductive material. 
     As used herein, “insulative material” means and includes electrically insulative material, such one or more of at least one dielectric oxide material (e.g., one or more of a silicon oxide (SiO x ), phosphosilicate glass, borosilicate glass, borophosphosilicate glass, fluorosilicate glass, an aluminum oxide (AlO x ), a hafnium oxide (HfO x ), a niobium oxide (NbO x ), a titanium oxide (TiO x ), a zirconium oxide (ZrO x ), a tantalum oxide (TaO x ), and a magnesium oxide (MgO x )), at least one dielectric nitride material (e.g., a silicon nitride (SiN y )), at least one dielectric oxynitride material (e.g., a silicon oxynitride (SiO x N y )), and at least one dielectric carboxynitride material (e.g., a silicon carboxynitride (SiO x C z N y )). Formulae including one or more of “x”, “y”, and “z” herein (e.g., SiO x , AlO x , HfO x , NbO x , TiO x , SiN y , SiO x N y , SiO x C z N y ) represent a material that contains an average ratio of “x” atoms of one element, “y” atoms of another element, and “z” atoms of an additional element (if any) for every one atom of another element (e.g., Si, Al, Hf, Nb, Ti). As the formulae are representative of relative atomic ratios and not strict chemical structure, an insulative material may comprise one or more stoichiometric compounds and/or one or more non-stoichiometric compounds, and values of “x”, “y”, and “z” (if any) may be integers or may be non-integers. As used herein, the term “non-stoichiometric compound” means and includes a chemical compound with an elemental composition that cannot be represented by a ratio of well-defined natural numbers and is in violation of the law of definite proportions. In addition, an “insulative structure” means and includes a structure formed of and including insulative material. 
     As used herein, the term “homogeneous” means relative amounts of elements included in a feature (e.g., a material, a structure) do not vary throughout different portions (e.g., different horizontal portions, different vertical portions) of the feature. Conversely, as used herein, the term “heterogeneous” means relative amounts of elements included in a feature (e.g., a material, a structure) vary throughout different portions of the feature. If a feature is heterogeneous, amounts of one or more elements included in the feature may vary stepwise (e.g., change abruptly), or may vary continuously (e.g., change progressively, such as linearly, parabolically) throughout different portions of the feature. The feature may, for example, be formed of and include a stack of at least two different materials. 
     Unless the context indicates otherwise, the materials described herein may be formed by any suitable technique including, but not limited to, spin coating, blanket coating, chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), atomic layer deposition (ALD), plasma enhanced ALD (PEALD), physical vapor deposition (PVD) (e.g., sputtering), or epitaxial growth. Depending on the specific material to be formed, the technique for depositing or growing the material may be selected by a person of ordinary skill in the art. In addition, unless the context indicates otherwise, removal of materials described herein may be accomplished by any suitable technique including, but not limited to, etching (e.g., dry etching, wet etching, vapor etching), ion milling, abrasive planarization (e.g., chemical-mechanical planarization (CMP)), or other known methods. 
       FIG.  1 A  through  FIG.  6 B  are various views (described in further detail below) illustrating a microelectronic device structure at different processing stages of a method of forming a microelectronic device (e.g., a memory device, such as a 3D NAND Flash memory device), in accordance with embodiments of the disclosure. With the description provided below, it will be readily apparent to one of ordinary skill in the art that the methods described herein may be used for forming various devices. In other words, the methods of the disclosure may be used whenever it is desired to form a microelectronic device. 
       FIG.  1 A  depicts a simplified, partial perspective view of a microelectronic device structure  100 . As shown in  FIG.  1 A , the microelectronic device structure  100  may be formed to include a preliminary stack structure  102  including a vertically alternating (e.g., in a Z-direction) sequence of insulative material  104  and sacrificial material  106  arranged in tiers  108 . Each of the tiers  108  of the preliminary stack structure  102  may individually include the sacrificial material  106  vertically neighboring (e.g., directly vertically adjacent) the insulative material  104 .  FIG.  1 B  is a simplified, longitudinal cross-sectional view of a portion A (identified with a dashed box in  FIG.  1 A ) of the microelectronic device structure  100  at the processing stage depicted in  FIG.  1 A .  FIG.  1 C  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure at the processing stage of  FIGS.  1 A and  1 B  about a dashed line B-B shown in  FIG.  1 B . 
     The insulative material  104  of each of the tiers  108  of the preliminary stack structure  102  may be formed of and include at least one dielectric material, such one or more of at least one dielectric oxide material (e.g., one or more of SiO x , phosphosilicate glass, borosilicate glass, borophosphosilicate glass, fluorosilicate glass, AlO x , HfO x , NbO x , TiO x , ZrO x , TaO x , and MgO x ), at least one dielectric nitride material (e.g., SiN y ), at least one dielectric oxynitride material (e.g., SiO x N y ), and at least one dielectric carboxynitride material (e.g., SiO x C z N y ). In some embodiments, the insulative material  104  of each of the tiers  108  of the preliminary stack structure  102  is formed of and includes a dielectric oxide material, such as SiO x  (e.g., SiO 2 ). The insulative material  104  of each of the tiers  108  may be substantially homogeneous, or the insulative material  104  of one or more (e.g., each) of the tiers  108  may be heterogeneous. 
     The sacrificial material  106  of each of the tiers  108  of the preliminary stack structure  102  may be formed of and include at least one material (e.g., at least one insulative material) that may be selectively removed relative to the insulative material  104 . The sacrificial material  106  may be selectively etchable relative to the insulative material  104  during common (e.g., collective, mutual) exposure to a first etchant; and the insulative material  104  may be selectively etchable to the sacrificial material  106  during common exposure to a second, different etchant. As used herein, a material is “selectively etchable” relative to another material if the material exhibits an etch rate that is at least about five times (5×) greater than the etch rate of another material, such as about ten times (10×) greater, about twenty times (20×) greater, or about forty times (40×) greater. By way of non-limiting example, depending on the material composition of the insulative material  104 , the sacrificial material  106  may be formed of and include one or more of at least one dielectric oxide material (e.g., one or more of SiO x , phosphosilicate glass, borosilicate glass, borophosphosilicate glass, fluorosilicate glass, AlO x , HfO x , NbO x , TiO x , ZrO x , TaO x , and a MgO x ), at least one dielectric nitride material (e.g., SiN y ), at least one dielectric oxynitride material (e.g., SiO x N y ), at least one dielectric oxycarbide material (e.g., SiO x C y ), at least one hydrogenated dielectric oxycarbide material (e.g., SiC x O y Hz), at least one dielectric carboxynitride material (e.g., SiO x C z N y ), and at least one semiconductive material (e.g., polycrystalline silicon). In some embodiments, the sacrificial material  106  of each of the tiers  108  of the preliminary stack structure  102  is formed of and includes a dielectric nitride material, such as SiN y  (e.g., Si 3 N 4 ). The sacrificial material  106  may, for example, be selectively etchable relative to the insulative material  104  during common exposure to a wet etchant comprising phosphoric acid (H 3 PO 4 ). 
     The preliminary stack structure  102  may be formed to include any desired number of the tiers  108 . By way of non-limiting example, the preliminary stack structure  102  may be formed to include greater than or equal to sixteen (16) of the tiers  108 , such as greater than or equal to thirty-two (32) of the tiers  108 , greater than or equal to sixty-four (64) of the tiers  108 , greater than or equal to one hundred and twenty-eight (128) of the tiers  108 , or greater than or equal to two hundred and fifty-six (256) of the tiers  108 . 
     As shown in  FIG.  1 A , the preliminary stack structure  102  may include stadium structures  110  formed therein. The stadium structures  110  may be distributed throughout the preliminary stack structure  102 . As shown in  FIG.  1 A , the preliminary stack structure  102  may include rows of the stadium structures  110  extending in parallel in a X-direction, and columns of the stadium structures  110  extending in a Y-direction orthogonal to the X-direction. The rows of the stadium structures  110  may individually include some of the stadium structures  110  at least partially (e.g., substantially) aligned with one another in the Y-direction. The columns of the of the stadium structures  110  may individually include other of the stadium structures  110  at least partially (e.g., substantially) aligned with one another in the X-direction. Different rows of the stadium structures  110  may be positioned within different horizontal areas of the preliminary stack structure  102  to be formed into different blocks of a stack structure to be formed from the preliminary stack structure  102 , as described in further detail below. In  FIG.  1 A , for clarity and ease of understanding the drawings and associated description, portions of the preliminary stack structure  102  are depicted as transparent to more clearly show some of the stadium structures  110  distributed within the preliminary stack structure  102 . 
     Still referring to  FIG.  1 A , at least some (e.g., each) of the stadium structures  110  within an individual row of the stadium structures  110  may be positioned at different vertical elevations in the Z-direction than one another. For example, as depicted in  FIG.  1 A , an individual row of the stadium structures  110  may include a first stadium structure  110 A, a second stadium structure  110 B at a relatively lower vertical position (e.g., in the Z-direction) within the preliminary stack structure  102  than the first stadium structure  110 A, a third stadium structure  110 C at a relatively lower vertical position within the preliminary stack structure  102  than the second stadium structure  110 B, and a fourth stadium structure  110 D at a relatively lower vertical position within the block  130  than the third stadium structure  110 C. In addition, within an individual row of the stadium structures  110 , horizontally neighboring (e.g., in the X-direction) stadium structures  110  may be substantially uniformly (e.g., equally, evenly) horizontally spaced apart from one another. In additional embodiments, one or more rows of the stadium structures  110  may individually include a different quantity of stadium structures  110  and/or a different distribution of stadium structures  110  than that depicted in  FIG.  1 A . For example, an individual row of the stadium structures  110  may include greater than four (4) of the stadium structures  110  (e.g., greater than or equal to five (5) of the stadium structures  110 , greater than or equal to ten (10) of the stadium structures  110 , greater than or equal to twenty-five (25) of the stadium structures  110 , greater than or equal to fifty (50) of stadium structures  110 ), or less than four (4) of the stadium structures  110  (e.g., less than or equal to three (3) of the stadium structures  110 , less than or equal to two (2) of the stadium structures  110 , only one (1) of the stadium structures  110 ). As another example, within an individual row of the stadium structures  110 , at least some horizontally neighboring stadium structures  110  may be at least partially non-uniformly (e.g., non-equally, non-evenly) horizontally spaced, such that at least one of the stadium structures  110  of the row is separated from at least two other of the stadium structures  110  of the row horizontally neighboring the at least one stadium structure  110  by different (e.g., non-equal) distances. As an additional non-limiting example, within an individual row of the stadium structures  110 , vertical positions (e.g., in the Z-direction) of the stadium structures  110  may vary in a different manner (e.g., may alternate between relatively deeper and relatively shallower vertical positions) than that depicted in  FIG.  1 A . 
     Each stadium structure  110  may include opposing staircase structures  112 , and a central region  114  horizontally interposed between (e.g., in the X-direction) the opposing staircase structures  112 . The opposing staircase structures  112  of each stadium structure  110  may include a forward staircase structure  112 A and a reverse staircase structure  112 B. A phantom line extending from a top of the forward staircase structure  112 A to a bottom of the forward staircase structure  112 A may have a positive slope, and another phantom line extending from a top of the reverse staircase structure  112 B to a bottom of the reverse staircase structure  112 B may have a negative slope. In additional embodiments, one or more of the stadium structures  110  may individually exhibit a different configuration than that depicted in  FIG.  1 A . As a non-limiting example, at least one stadium structure  110  may be modified to include a forward staircase structure  112 A but not a reverse staircase structure  112 B (e.g., the reverse staircase structure  112 B may be absent), or at least one stadium structure  110  may be modified to include a reverse staircase structure  112 B but not a forward staircase structure  112 A (e.g., the forward staircase structure  112 A may be absent). In such embodiments, the central region  114  horizontally neighbors a bottom of the forward staircase structure  112 A (e.g., if the reverse staircase structure  112 B is absent), or the central region  114  horizontally neighbors a bottom of the reverse staircase structure  112 B (e.g., if the forward staircase structure  112 A is absent). 
     The opposing staircase structures  112  (e.g., the forward staircase structure  112 A and the reverse staircase structure  112 B) of an individual stadium structure  110  each include steps  116  defined by edges (e.g., horizontal ends) of the tiers  108  of the preliminary stack structure  102 . For the opposing staircase structures  112  of an individual stadium structure  110 , each step  116  of the forward staircase structure  112 A may have a counterpart step  116  within the reverse staircase structure  112 B having substantially the same geometric configuration (e.g., shape, dimensions), vertical position (e.g., in the Z-direction), and horizontal distance (e.g., in the X-direction) from a horizontal center (e.g., in the X-direction) of the central region  114  of the stadium structure  110 . In additional embodiments, at least one step  116  of the forward staircase structure  112 A does not have a counterpart step  116  within the reverse staircase structure  112 B having substantially the same geometric configuration (e.g., shape, dimensions), vertical position (e.g., in the Z-direction), and/or horizontal distance (e.g., in the X-direction) from horizontal center (e.g., in the X-direction) of the central region  114  of the stadium structure  110 ; and/or at least one step  116  of the reverse staircase structure  112 B does not have a counterpart step  116  within the forward staircase structure  112 A having substantially the same geometric configuration (e.g., shape, dimensions), vertical position (e.g., in the Z-direction), and/or horizontal distance (e.g., in the X-direction) from horizontal center (e.g., in the X-direction) of the central region  114  of the stadium structure  110 . 
     Each of the stadium structures  110  of the preliminary stack structure  102  may individually include a desired quantity of steps  116 . Each of the stadium structures  110  may include substantially the same quantity of steps  116  as each other of the stadium structures  110 , or at least one of the stadium structures  110  may include a different quantity of steps  116  than at least one other of the stadium structures  110 . In some embodiments, at least one of the stadium structures  110  includes a different (e.g., greater, lower) quantity of steps  116  than at least one other of the stadium structures  110 . As shown in  FIG.  1 A , in some embodiments, the steps  116  of each of the stadium structures  110  are arranged in order, such that steps  116  directly horizontally adjacent (e.g., in the X-direction) one another correspond to tiers  108  of the preliminary stack structure  102  directly vertically adjacent (e.g., in the Z-direction) one another. In additional embodiments, the steps  116  of at least one of the stadium structures  110  are arranged out of order, such that at least some steps  116  of the stadium structure  110  directly horizontally adjacent (e.g., in the X-direction) one another correspond to tiers  108  of preliminary stack structure  102  not directly vertically adjacent (e.g., in the Z-direction) one another. 
     With continued reference to  FIG.  1 A , for an individual stadium structure  110 , the central region  114  thereof may horizontally intervene (e.g., in the X-direction) between and separate the forward staircase structure  112 A thereof from the reverse staircase structure  112 B thereof. The central region  114  may horizontally neighbor a vertically lowermost step  116  of the forward staircase structure  112 A, and may also horizontally neighbor a vertically lowermost step  116  of the reverse staircase structure  112 B. The central region  114  of an individual stadium structure  110  may have desired horizontal dimensions. In addition, the central region  114  of each of the stadium structures  110  may have substantially the same horizontal dimensions as the central region  114  of each other of the stadium structures  110 , or the central region  114  of at least one of the stadium structures  110  may have different horizontal dimensions than the central region  114  of at least one other of the stadium structures  110 . 
     Still referring to  FIG.  1 A , each stadium structure  110  (including the forward staircase structure  112 A, the reverse staircase structure  112 B, and the central region  114  thereof) within the preliminary stack structure  102  may individually partially define boundaries (e.g., horizontal boundaries, vertical boundaries) of a trench  118  vertically extending (e.g., in the Z-direction) through the preliminary stack structure  102 . The portions of the preliminary stack structure  102  horizontally neighboring an individual stadium structure  110  may also partially define the boundaries of the trench  118  associated with the stadium structure  110 . The trench  118  may only vertically extend through tiers  108  of the preliminary stack structure  102  defining the forward staircase structure  112 A and the reverse staircase structure  112 B of the stadium structure  110 ; or may also vertically extend through additional tiers  108  of the preliminary stack structure  102  not defining the forward staircase structure  112 A and the reverse staircase structure  112 B of the stadium structure  110 , such as additional tiers  108  of the preliminary stack structure  102  vertically overlying the stadium structure  110 . Edges of the additional tiers  108  of the preliminary stack structure  102  may, for example, define one or more additional stadium structures vertically overlying and horizontally offset from the stadium structure  110 . The trench  118  may subsequently be filled with one or more dielectric materials, as described in further detail below. 
     As previously described,  FIG.  1 B  is a simplified, longitudinal cross-sectional view of portion A (identified with a dashed box in  FIG.  1 A ) of the microelectronic device structure  100  at the processing stage depicted in  FIG.  1 A . The portion A encompasses the first stadium structure  110 A of an individual row of the stadium structures  110  within the preliminary stack structure  102  ( FIG.  1 A ). The portion A also encompasses regions of the preliminary stack structure  102  horizontally neighboring the first stadium structure  110 A in the X-direction and the Y-direction. While additional features (e.g., structures, materials) of the microelectronic device structure  100  are described hereinbelow with reference to the portion A of the microelectronic device structure  100 , such additional features may also be formed and included in additional portions of the microelectronic device structure  100 , including additional portions encompassing additional stadium structures  110  of the preliminary stack structure  102  ( FIG.  1 A ) and additional regions of the preliminary stack structure  102  having boundaries defined by the additional stadium structures  110 . 
     In addition, as also previously described,  FIG.  1 C  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure  100  at the processing stage of  FIGS.  1 A and  1 B  about a dashed line B-B shown in  FIG.  1 B . As shown in  FIG.  1 C , the insulative material  104  and the sacrificial material  106  of each tier  108  of the preliminary stack structure  102  having horizontal ends defining an individual stadium structure  110  (e.g., the first stadium structure  110 A) within the preliminary stack structure  102  may continuously horizontally extend in the X-direction across sides of the stadium structure  110  opposing one another in the Y-direction. In addition, for an individual stadium structure  110  within the preliminary stack structure  102 , inner horizontal boundaries (e.g., inner sidewalls) of the preliminary stack structure  102  partially defining the trench  118  associated with (e.g., vertically overlying and within horizontal boundaries of) the stadium structure  110  may be oriented substantially perpendicular to uppermost vertical boundaries (e.g., uppermost surfaces) of the preliminary stack structure  102 , or may be oriented substantially non-perpendicular to the uppermost vertical boundaries (e.g., uppermost surfaces) of the preliminary stack structure  102 . 
     Referring next to  FIG.  2 A , which is a simplified, longitudinal cross-sectional view of the portion A of the microelectronic device structure  100  following the processing stage previously described with reference to  FIGS.  1 A through  1 C , a dielectric liner material  120  may be formed on or over portions of the preliminary stack structure  102  defining the stadium structures  110  and the trenches  118 . The dielectric liner material  120  may partially (e.g., less than completely) fill each of the trenches  118 . For an individual trench  118 , the dielectric liner material  120  may be formed to substantially continuously extend on or over surfaces (e.g., horizontally extending surfaces, vertically extending surfaces) of the stadium structure  110  and the preliminary stack structure  102  defining boundaries (e.g., horizontal boundaries, vertical boundaries) of the trench  118 . The dielectric liner material  120  may be formed to substantially continuously extend on or over surfaces of the opposing staircase structures  112  (e.g., the forward staircase structure  112 A and the reverse staircase structure  112 B) of each of the stadium structures  110 , as well as on or over inner sidewalls of the preliminary stack structure  102  horizontally neighboring (e.g., in the Y-direction) each of the stadium structures  110 . The dielectric liner material  120  may also be formed to extend beyond boundaries (e.g., horizontal boundaries, vertical boundaries) of the trenches  118 . For example, dielectric liner material  120  may also be formed to extend over uppermost surfaces of the preliminary stack structure  102  outside the horizontal boundaries (e.g., in the X-direction and in the Y-direction) of the trenches  118 .  FIG.  2 B  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure  100  at the processing stage of  FIG.  2 A  about a dashed line B-B shown in  FIG.  2 A . 
     The dielectric liner material  120  may be employed (e.g., serve) as a barrier material to protect (e.g., mask) subsequently formed structures (e.g., subsequently formed dielectric structures) from removal during subsequent processing acts (e.g., subsequent replacement gate processing acts, such as subsequent etching acts), as described in further detail below. The dielectric liner material  120  may be formed to have a desired thickness capable of protecting the subsequently formed structures during the subsequent processing acts. In some embodiments, a thickness of the dielectric liner material  120  is within a range of from about 5 nanometers (nm) to about 100 nm (e.g., from about 10 nm to about 50 nm, from about 10 nm to about 30 nm). 
     The dielectric liner material  120  may be formed of and include at least one dielectric material having different etch selectivity than the sacrificial material  106  of the tiers  108  of the preliminary stack structure  102 . The dielectric liner material  120  may also have different etch selectivity than at least one additional dielectric material to subsequently be formed within remaining portions the trenches  118 . The dielectric liner material  120  may, for example, have etch selectively substantially similar to that of the insulative material  104  of the tiers  108  of the preliminary stack structure  102 . By way of non-limiting example, the dielectric liner material  120  may be formed of and include at least one oxygen-containing dielectric material, such as a one or more of at least one dielectric oxide material (e.g., one or more of SiO x , phosphosilicate glass, borosilicate glass, borophosphosilicate glass, fluorosilicate glass, AlO x , HfO x , NbO x , and TiO x ), at least one dielectric oxynitride material (e.g., SiO x N y ), and at least one dielectric carboxynitride material (e.g., SiO x C z N y ). In some embodiments, the dielectric liner material  120  is formed of and includes SiO x  (e.g., SiO 2 ). The dielectric liner material  120  may be substantially homogeneous, or may be heterogeneous. 
     Referring next to  FIG.  3 A , which is a simplified, longitudinal cross-sectional view of the portion A of the microelectronic device structure  100  following the processing stage previously described with reference to  FIGS.  2 A and  2 B , dielectric structures  122  (e.g., dielectric mesa structures) may be formed on or over portions of the dielectric liner material  120  within horizontal areas of the steps  116  of the stadium structures  110 , and then a dielectric fill material  124  may be formed on or over the dielectric structures  122  and the dielectric liner material  120 . The dielectric structures  122  and the dielectric fill material  124  may together substantially fill portions of the trenches  118  ( FIGS.  2 A and  2 B ) remaining unfilled following the formation of the dielectric liner material  120 . The dielectric liner material  120 , the dielectric structures  122 , and the dielectric fill material  124  may together form filled trenches  126  individually vertically extending (e.g., in the Z-direction) through the preliminary stack structure  102 .  FIG.  3 B  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure  100  at the processing stage of  FIG.  3 A  about a dashed line B-B shown in  FIG.  3 A . 
     The dielectric structures  122  may be employed (e.g., serve) as etch stop structures during subsequent processing acts (e.g., subsequent etching acts) to form openings (e.g., contact openings, contact vias) vertically extending through the dielectric fill material  124 , as described in further detail below. The dielectric structures  122  may be formed to discontinuously extend on or over portions of the dielectric liner material  120  within horizontal boundaries of the stadium structures  110 . Individual dielectric structures  122  may be positioned within horizontal boundaries of individual steps  116  of individual stadium structures  110  (e.g., individual steps  116  of the opposing staircase structures  112  thereof, such individual steps  116  the forward staircase structure  112 A and/or individual steps  116  of the reverse staircase structure  112 B) within the preliminary stack structure  102 . As shown in  FIG.  3 A , for each stadium structure  110 , at least one dielectric structure  122  may also be positioned within horizontal boundaries of the central region  114  of the stadium structure  110 . Each dielectric structure  122  may be substantially confined within a horizontal area of the step  116  or central region  114  associated therewith. Each dielectric structure  122  within horizontal boundaries of an individual step  116  of an individual stadium structure  110  may have a horizontal area less than a horizontal area of the step  116 . In addition, each dielectric structure  122  within horizontal boundaries of an individual central region  114  of an individual stadium structure  110  may have a horizontal area less than a horizontal area of the central region  114 . Each dielectric structure  122  may be formed to have a desired thickness capable of protecting the dielectric liner material  120  underlying the dielectric structure  122  from during the subsequent processing acts to form the openings vertically extending through the dielectric fill material  124 . In some embodiments, a thickness of each dielectric structure  122  is within a range of from about 10 nm to about 100 nm (e.g., from about 20 nm to about 80 nm). 
     As shown in  FIGS.  3 A and  3 B , vertically extending (e.g., in the Z-direction) surfaces of the dielectric liner material  120  may be substantially free of the dielectric structures  122  thereon. For example, the dielectric structures  122  may be absent (e.g., omitted) from portions of the dielectric liner material  120  formed on or over vertically extending surfaces of the preliminary stack structure  102  partially defining boundaries of the trenches  118  ( FIGS.  1 A- 1 C ), such as vertically extending surfaces of the stadium structures  110  and vertically extending surfaces (e.g., sidewalls) of portions of the preliminary stack structure  102  horizontally neighboring the stadium structures  110  (and, hence, also horizontally neighboring the trenches  118 ). Within horizontal boundaries of an individual stadium structure  110 , each of the dielectric structures  122  may be horizontally offset in the X-direction from each other of the dielectric structures  122 . In addition, within horizontal boundaries of an individual stadium structure  110 , each of the dielectric structures  122  may be at least partially (e.g., substantially) horizontally aligned in the Y-direction with each other of the dielectric structures  122 . 
     The dielectric structures  122  may be formed of and include at least one dielectric material having different etch selectivity than the dielectric liner material  120  and the dielectric fill material  124 . The dielectric structures  122  may, for example, have etch selectively substantially similar to that of the sacrificial material  106  of the tiers  108  of the preliminary stack structure  102 . By way of non-limiting example, the dielectric structures  122  may be formed of and include at least one nitrogen-containing dielectric material, such as at least one dielectric nitride material. In some embodiments, each of the dielectric structures  122  is each formed of and includes SiN y  (e.g., Si 3 N 4 ). The dielectric structures  122  may individually be substantially homogeneous, or may individually be heterogeneous. 
     The dielectric structures  122  may be formed by forming at least one dielectric material on or over the dielectric liner material  120 , and then removing portions of the dielectric material on or over vertically extending (e.g., in the Z-direction) surfaces of the dielectric liner material  120  within the trenches  118  ( FIGS.  2 A and  2 B ). Additional portions of the dielectric material on or over horizontally extending surfaces of the dielectric liner material  120  within the trenches  118  ( FIGS.  2 A and  2 B ) that remain following the material removal process may form the dielectric structures  122 . The portions of the dielectric material on or over the vertically extending surfaces of the dielectric liner material  120  may be selectively removed relative to the additional portions of the dielectric material on or over the horizontally extending surfaces of the dielectric liner material  120  by doping the portions or the additional portions with at least one chemical species (e.g., at least one dopant) than modifies the etch selectively of the portions relativity to the additional portions prior to mutual exposure of the portions and the additional portions to at least one etchant. In some embodiments, the additional, horizontally extending portions of the dielectric material are doped with a relatively greater amount of at least one chemical species than the vertically extending portions of the dielectric material, wherein the at least one chemical species effectively decreases an etch rate of the additional, horizontally extending portions relative to the vertically extending portions of the dielectric material during mutual exposure to a predetermined etchant (e.g., a predetermined wet etchant, such as a wet etchant include hydrofluoric acid, HF). By way of non-limiting example, the additional, horizontally extending portions of the dielectric material may be doped with a relatively greater amount of carbon (C) than the vertically extending portions of the dielectric material. In additional embodiments, the vertically extending portions of the dielectric material are doped with a relatively greater amount of at least one chemical species than the additional, horizontally extending portions of the dielectric material, wherein the at least one chemical species effectively increases an etch rate of the vertically extending portions relative to the additional, horizontally extending portions during mutual exposure to a predetermined etchant. 
     Still referring to  FIGS.  3 A and  3 B , the dielectric fill material  124  may substantially fill portions of the trenches  118  ( FIGS.  2 A and  2 B ) unoccupied by the dielectric liner material  120  and the dielectric structures  122 . The dielectric fill material  124  may be formed to substantially continuously extend on or over the dielectric structures  122  and the dielectric liner material  120 . The dielectric fill material  124  may be formed to exhibit a substantially planer upper vertical boundary, and a substantially non-planar lower vertical boundary complementary to (e.g., substantially mirroring) a topography thereunder. 
     As shown in  FIGS.  3 A and  3 B , within horizontal boundaries of each of the stadium structures  110 , the dielectric fill material  124  covers and surrounds the dielectric structures  122 . For example, the dielectric fill material  124  may substantially cover and surround horizontally extending upper surfaces and vertically extending side surfaces of each of the dielectric structures  122 . In addition, within horizontal boundaries of each of the stadium structures  110 , the dielectric fill material  124  also covers portions of the dielectric liner material  120  not covered by the dielectric structures  122 . For example, the dielectric fill material  124  may substantially cover surfaces (e.g., horizontally extending surfaces, vertically extending surfaces) of the dielectric liner material  120  not covered by the dielectric structures  122 . Portions of the dielectric fill material  124  may be horizontally interposed (e.g., in the X-direction, in the Y-direction) between the dielectric structures  122  and the dielectric liner material  120 . 
     The dielectric fill material  124  may be formed of and include at least one dielectric material having different etch selectivity than the dielectric structures  122 . The dielectric fill material  124  may, for example, have etch selectively substantially similar to that of one or more of the dielectric liner material  120  the insulative material  104  of the tiers  108  of the preliminary stack structure  102 . By way of non-limiting example, the dielectric fill material  124  may be formed of and include at least one oxygen-containing dielectric material, such as a one or more of at least one dielectric oxide material (e.g., one or more of SiO x , phosphosilicate glass, borosilicate glass, borophosphosilicate glass, fluorosilicate glass, AlO x , HfO x , NbO x , and TiO x ), at least one dielectric oxynitride material (e.g., SiO x N y ), and at least one dielectric carboxynitride material (e.g., SiO x C z N y ). In some embodiments, the dielectric fill material  124  is formed of and includes SiO x  (e.g., SiO 2 ). 
     As described in further detail below with reference to  FIG.  4 C , the microelectronic device structure  100  may be formed to further include support pillars vertically extending through the preliminary stack structure  102 . The support pillars may be configured and positioned to support the tiers  108  of the preliminary stack structure  102  during subsequent processing (e.g., replacement gate processing) of the microelectronic device structure  100 . For example, the support pillars may be configured and positioned to impede (e.g., substantially prevent) collapse of portions of the insulative material  104  of the tiers  108  with horizontal areas of the stadium structures  110  during subsequent replacement gate processing acts. 
     Referring next to  FIG.  4 A , which is a simplified, partial perspective view of a microelectronic device structure  100  following the processing stage previously described with reference to  FIGS.  3 A and  3 B , the preliminary stack structure  102  ( FIGS.  3 A and  3 B ) may be partitioned (e.g., divided, segmented) and subject to replacement gate processing to form a stack structure  128 . The stack structure  128  may be divided into blocks  130  separated from one another by slot structures  132 . The slot structures  132  may vertically extend (e.g., in the Z-direction) completely through the stack structure  128 . Additional features (e.g., materials, structures) of the stack structure  128  (including the blocks  130  thereof) are described in further detail below. In  FIG.  4 A , for clarity and ease of understanding the drawings and associated description, the slot structures  132  are depicted as transparent to more clearly show features of the blocks  130 .  FIG.  4 B  is a simplified, longitudinal cross-sectional view of the portion A of the microelectronic device structure  100  at the processing stage depicted in  FIG.  4 A .  FIG.  4 C  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure  100  at the processing stage of  FIGS.  4 A and  4 B  about a dashed line B-B shown in  FIG.  4 B . 
     As shown in  FIG.  4 A , the blocks  130  of the stack structure  128  may be formed to horizontally extend parallel in an X-direction. As used herein, the term “parallel” means substantially parallel. Horizontally neighboring blocks  130  of the stack structure  128  may be separated from one another in a Y-direction orthogonal to the X-direction by the slot structures  132 . The slot structures  132  may also horizontally extend parallel in the X-direction. Each of the blocks  130  of the stack structure  128  may exhibit substantially the same geometric configuration (e.g., substantially the same dimensions and substantially the same shape) as each other of the blocks  130 , or one or more of the blocks  130  may exhibit a different geometric configuration (e.g., one or more different dimensions and/or a different shape) than one or more other of the blocks  130 . In addition, each pair of horizontally neighboring blocks  130  of the stack structure  128  may be horizontally separated from one another by substantially the same distance (e.g., corresponding to a width in the Y-direction of each of the slot structures  132 ) as each other pair of horizontally neighboring blocks  130  of the stack structure  128 , or at least one pair of horizontally neighboring blocks  130  of the stack structure  128  may be horizontally separated from one another by a different distance than that separating at least one other pair of horizontally neighboring blocks  130  of the stack structure  128 . In some embodiments, the blocks  130  of the stack structure  128  are substantially uniformly (e.g., substantially non-variably, substantially equally, substantially consistently) sized, shaped, and spaced relative to one another. 
     Each of the blocks  130  of the stack structure  128  may be formed to including a vertically alternating (e.g., in a Z-direction) sequence of insulative structures  134  and conductive structures  136  arranged in tiers  138 . For an individual blocks  130  of the stack structure  128 , each of the tiers  138  may individually include one of the conductive structures  136  vertically neighboring (e.g., directly vertically adjacent) one of the insulative structures  134 . The insulative structures  134  of the blocks  130  of the stack structure  128  may comprise portions of the insulative material  104  ( FIGS.  3 A and  3 B ) of the preliminary stack structure  102  ( FIGS.  3 A and  3 B ) remaining following the formation of the blocks  130 . The conductive structures  136  of the blocks  130  of the stack structure  128  may comprise at least one conductive material formed (e.g., deposited) in place of the sacrificial material  106  ( FIGS.  3 A and  3 B ) of the preliminary stack structure  102  ( FIGS.  3 A and  3 B ) through the replacement gate process, as described in further detail below. The conductive material may formed of and include one or more of at least one conductively doped semiconductor material, at least one metal, at least one alloy, and at least one conductive metal-containing material (e.g., at last one conductive metal nitride, at least one conductive metal silicide, at least one conductive metal carbide, at least one conductive metal oxide). In some embodiments, the conductive structures  136  are formed of and includes W. Optionally, at least one liner material (e.g., at least one insulative liner material, at least one conductive liner materials) may be formed around the conductive structures  136 . The liner material may, for example, be formed of and include one or more a metal (e.g., titanium, tantalum), an alloy, a metal nitride (e.g., tungsten nitride, titanium nitride, tantalum nitride), and a metal oxide (e.g., aluminum oxide). In some embodiments, the liner material comprises at least one conductive material employed as a seed material for the formation of the conductive structures  136 . In some embodiments, the liner material comprises titanium nitride (TiN x , such as TiN). In further embodiments, the liner material further includes aluminum oxide (AlO x , such as Al 2 O 3 ). As a non-limiting example, for each of the block  130  of the stack structure  128 , AlO x  (e.g., Al 2 O 3 ) may be formed directly adjacent the insulative structures  134 , TiN x  (e.g., TiN) may be formed directly adjacent the AlO x , and W may be formed directly adjacent the TiN x . For clarity and ease of understanding the description, the liner material is not illustrated in  FIGS.  4 A- 4 C , but it will be understood that the liner material may be disposed around the conductive structures  136 . 
     Within each block  130  of the stack structure  128 , one or more conductive structures  136  of one or more relatively vertically higher tiers  138  (e.g., upper tiers) may be employed to form upper select gate structures (e.g., drain side select gate (SGD) structures) for upper select transistors (e.g., drain side select transistors) of the block  130 . The conductive structures  136  of the relatively vertically higher tiers  138  may be segmented by one or more filled slot(s) (e.g., filled SGD slot(s)) to form the upper select gate structures of the block  130 . In some embodiments, within each block  130  of the stack structure  128 , the conductive structures  136  of each of less than or equal to eight (8) relatively higher tiers  138  (e.g., from one (1) relatively vertically higher tier  138  to eight (8) relatively vertically higher tiers  138 ) of the stack structure  128  is employed to form upper select gate structures (e.g., SGD structures) for the block  130 . In addition, within each block  130  of the stack structure  128 , the conductive structures  136  of at least some relatively vertically lower tiers  138  vertically underlying the relatively vertically higher tiers  138  may be employed to form access line structures (e.g., word line structures) of the block  130 . Moreover, within each block  130  of the stack structure  128 , the conductive structures  136  of at least a vertically lowest tier  138  may be employed to form as at least one lower select gate structure (e.g., at least one source side select gate (SGS) structure) for lower select transistors (e.g., source side select transistors) of the block  130 . 
     To form the stack structure  128 , including the blocks  130  thereof, slots (e.g., trenches, openings, apertures) having geometric configurations (e.g., shapes, dimensions) and positions corresponding to (e.g., substantially the same as) having geometric configurations (e.g., shapes, dimensions) and positions of the slot structures  132  may be formed in the preliminary stack structure  102  ( FIGS.  3 A and  3 B ). Thereafter, the microelectronic device structure  100  may be treated with at least one wet etchant formulated to selectively remove portions of the sacrificial material  106  ( FIGS.  3 A and  3 B ) of the tiers  108  ( FIGS.  3 A and  3 B ) of the preliminary stack structure  102  ( FIGS.  3 A and  3 B ) through the slots. The wet etchant may be selected to remove the portions of the sacrificial material  106  ( FIGS.  3 A and  3 B ) without substantially removing portions of the insulative material  104  ( FIGS.  3 A and  3 B ) of the tiers  108  ( FIGS.  3 A and  3 B ) of the preliminary stack structure  102  ( FIGS.  3 A and  3 B ), and without substantially removing portions of the dielectric liner material  120 . During the material removal process, the dielectric liner material  120  may protect (e.g., mask) the dielectric structures  122  from being removed. In some embodiments wherein the sacrificial material  106  ( FIGS.  3 A and  3 B ) comprises a dielectric nitride material (e.g., SiN y , such as Si 3 N 4 ) and the insulative material  104  and the dielectric liner material  120  comprise a dielectric oxide material (e.g., SiO x , such as SiO 2 ), the sacrificial material  106  ( FIGS.  3 A and  3 B ) of the tiers  108  ( FIGS.  3 A and  3 B ) of the preliminary stack structure  102  ( FIGS.  3 A and  3 B ) is at selectively removed using a wet etchant comprising H 3 PO 4 . Following the selective removal of the portions of the sacrificial material  106  ( FIGS.  3 A and  3 B ), the resulting recesses may be filled with conductive material to form the conductive structures  136  of the blocks  130  of the stack structure  128 . In addition, following the formation of the blocks  130 , the slots between the blocks  130  may be filled (e.g., substantially filled) with at least one dielectric material (e.g., at least one dielectric oxide material, such as SiO x ; at least one dielectric nitride material, such as SiN y ) to form the slot structures  132 . In some embodiments, the slot structures  132  are formed of and include SiO 2 . The slot structures  132  may individually be formed to be substantially homogeneous, or may individually be formed to be heterogeneous. 
     Referring again to  FIG.  4 A , each block  130  of the stack structure  128  may individually be formed to include a row of the stadium structures  110  (e.g., including the first stadium structure  110 A, the second stadium structure  110 B, the third stadium structure  110 C, and the fourth stadium structure  110 D of the row), crest regions  140  (e.g., elevated regions), and bridge regions  142  (e.g., additional elevated regions). The stadium structures  110  may be distributed throughout and substantially confined within a horizontal area of the block  130 . The crest regions  140  may be horizontally interposed between stadium structures  110  horizontally neighboring one another in the X-direction. The bridge regions  142  may horizontally neighbor opposing sides of individual stadium structures  110  in the Y-direction, and may horizontally extend from and between crest regions  140  horizontally neighboring one another in the X-direction. In  FIG.  4 A , for clarity and ease of understanding the drawings and associated description, portions (e.g., some of the bridge regions  142  horizontally neighboring first sides of the stadium structures  110  in the Y-direction) of one of the blocks  130  of the stack structure  128  are depicted as transparent to more clearly show the stadium structures  110  distributed within the block  130 . 
     As shown in  FIG.  4 A , the crest regions  140  of an individual block  130  of the stack structure  128  may intervene between and separate stadium structures  110  horizontally neighboring one another in the X-direction. For example, one of the crest regions  140  may intervene between and separate the first stadium structure  110 A and the second stadium structure  110 B, an additional one of the crest regions  140  may intervene between and separate the second stadium structure  110 B and the third stadium structure  110 C; and a further one of the crest regions  140  may intervene between and separate the third stadium structure  110 C and the fourth stadium structure  110 D. A vertical height of the crest regions  140  in the Z-direction may be substantially equal to a maximum vertical height of the block  130  in the Z-direction; and a horizontal width of the crest regions  140  in the Y-direction may be substantially equal to a maximum horizontal width of the block  130  in the Y-direction. In addition, each of the crest regions  140  may individually exhibit a desired horizontal length in the X-direction. Each of the crest regions  140  of an individual block  130  of the stack structure  128  may exhibit substantially the same horizontal length in the X-direction as each other of the crest regions  140  of the block  130 ; or at least one of the crest regions  140  of the block  130  may exhibit a different horizontal length in the X-direction than at least one other of the crest regions  140  of the block  130 . 
     Still referring to  FIG.  4 A , the bridge regions  142  of an individual block  130  of the stack structure  128  may be formed to intervene between and separate the stadium structures  110  of the block  130  from the slot structures  132  horizontally neighboring the block  130  in the Y-direction. For example, for each stadium structure  110  within an individual block  130  of the stack structure  128 , a first bridge region  142 A may be horizontally interposed in the Y-direction between a first side of the stadium structure  110  and a first of the slot structures  132  horizontally neighboring the block  130 ; and a second bridge region  142 B may be horizontally interposed in the Y-direction between a second side of the stadium structure  110  and a second of the slot structures  132  horizontally neighboring the block  130 . The first bridge region  142 A and the second bridge region  142 B may horizontally extend in parallel in the X-direction. In addition, the first bridge region  142 A and the second bridge region  142 B may each horizontally extend from and between crest regions  140  of the block  130  horizontally neighboring one another in the X-direction. The bridge regions  142  of the block  130  may be integral and continuous with the crest regions  140  of the block  130 . Upper boundaries (e.g., upper surfaces) of the bridge regions  142  may be substantially coplanar with upper boundaries of the crest regions  140 . A vertical height of the bridge regions  142  in the Z-direction may be substantially equal to a maximum vertical height of the block  130  in the Z-direction. In addition, each of the bridge regions  142  (including each first bridge region  142 A and each second bridge region  142 B) may individually exhibit a desired horizontal width in the Y-direction and a desired horizontal length in the X-direction. Each of the bridge regions  142  of the block  130  may exhibit substantially the same horizontal length in the X-direction as each other of the bridge regions  142  of the block  130 ; or at least one of the bridge regions  142  of the block  130  may exhibit a different horizontal length in the X-direction than at least one other of the bridge regions  142  of the block  130 . In addition, each of the bridge regions  142  of the block  130  may exhibit substantially the same horizontal width in the Y-direction as each other of the bridge regions  142  of the block  130 ; or at least one of the bridge regions  142  of the block  130  may exhibit a different horizontal width in the Y-direction than at least one other of the bridge regions  142  of the block  130 . 
     For each block  130  of the stack structure  128 , the bridge regions  142  thereof horizontally extend around the filled trenches  126  of the block  130 . Some of the bridge regions  142  of the block  130  may be employed to form continuous conductive paths extending from and between horizontally neighboring crest regions  140  of the block  130 . As shown in  FIG.  4 C , the dielectric liner material  120  of the filled trenches  126  may be positioned directly horizontally adjacent (e.g., in the Y-direction) inner side surfaces (e.g., inner sidewalls) of the bridge regions  142 , and the slot structures  132  may be positioned directly horizontally adjacent (e.g., in the Y-direction) outer side surfaces (e.g., outer sidewalls) of the bridge regions  142 . Vertically extending portions of dielectric liner material  120  directly horizontally adjacent the inner side surfaces of the bridge regions  142  are substantially free of the dielectric structures  122  thereon. Instead, the dielectric fill material  124  of the filled trenches  126  may be positioned directly horizontally adjacent (e.g., in the Y-direction) and may substantially cover inner side surfaces (e.g., inner sidewalls) of the vertically extending portions of dielectric liner material  120 . In addition, for each filled trench  126 , the dielectric liner material  120  is vertically interposed between upper boundaries of the steps  116  of the stadium structure  110  associated with the filled trench  126  and lower boundaries of the dielectric structures  122  within horizontal boundaries of the steps  116 . 
     Referring to  FIG.  4 C , during and after the replacement gate process to form the stack structure  128 , the configuration of the filled trenches  126  (including the configurations of the dielectric liner material  120 , the dielectric structures  122 , and the dielectric fill material  124  thereof) provides several advantages. For example, the configuration of the dielectric liner material  120  of each filled trench  126  protects the dielectric structures  122  of the filled trenches  126  from removal and replacement with conductive material during the replacements gate process, and thus prevents the formation of undesirable void spaces that may otherwise result from replacing the dielectric structures  122  with the conductive material. Such void spaces may, for example, otherwise be formed at interfaces of the conductive material that would replace the dielectric structures  122  and the conductive structures  136  of individual blocks  130  of the stack structure  128  at steps  116  of the stadium structures  110 . Maintaining the dielectric structures  122  also facilitates subsequent use of the dielectric structures  122  as so-called “etch stop” structures to mitigate (e.g., prevent) undesirable damage (e.g., over-etching damage, punch-through damage) to tiers  138  of individual blocks  130  of the stack structure  128  during subsequent processing to form contact openings within boundaries of the blocks  130 , as described in further detail below. As another example, the configurations of the dielectric structures  122  of each filled trench  126  prevents undesirable damage, defects, and/or processing difficulties that may otherwise occur if the dielectric structures  122  vertically extended across and substantially covered (e.g., substantially lined) vertically extending portions of dielectric liner material  120 . Omitting the dielectric structures  122  from vertically extending portions of the dielectric liner material  120  may, for example, prevent undesirable short circuits between the conductive structures  136  of different tiers  138  of an individual block  130  that may otherwise result from defects within the dielectric liner material  120  ahead of the replacement gate processing. Such defects may, for example, otherwise provide an access point for undesirable replacement of vertically extending portions of such dielectric structure configurations with conductive material during the replacement gate processing. 
     Still referring to  FIG.  4 C , each block  130  of the stack structure  128  may individually be formed to have a desired distribution of support structures  141  (e.g., support contacts, support pillars) (depicted by way of dashed lines in  FIG.  4 C ) vertically extending therethrough. The support structures  141  may, for example, be formed in the preliminary stack structure  102  ( FIGS.  3 A and  3 B ) prior to the replacement gate processing to form the conductive structures  136  of the blocks  130  of the stack structure  128 . The support structures  141  may be configured and positioned to facilitating support of the insulative material  104  ( FIGS.  3 A and  3 B ) of each of the tiers  108  ( FIGS.  3 A and  3 B ) of the preliminary stack structure  102  ( FIGS.  3 A  and  3 B) during replacement of the sacrificial material  106  ( FIGS.  3 A and  3 B ) of the tiers  108  ( FIGS.  3 A and  3 B ) with the conductive structures  136 . In some embodiments, each block  130  of the stack structure  128  includes at least one array of the support structures  141  vertically extending therethrough, including rows of the support structures  141  extending in the X-direction, and columns of the support structures  141  extending to the Y-direction. For each block  130 , portions of the at least one array of the support structures  141  may be located within horizontal areas of the stadium structures  110  within the block  130 . 
     The support structures  141  may each individually be formed to exhibit a desired horizontal cross-sectional shape. In some embodiments, each of the support structures  141  is formed to exhibit a substantially circular horizontal cross-sectional shape. In additional embodiments, one or more (e.g., each) of the support structures  141  exhibits a non-circular cross-sectional shape, such as one of more of a square cross-sectional shape, a rectangular cross-sectional shape, an oblong cross-sectional shape, an elliptical cross-sectional shape, a tear drop cross-sectional shape, a semicircular cross-sectional shape, a tombstone cross-sectional shape, a crescent cross-sectional shape, a triangular cross-sectional shape, a kite cross-sectional shape, and an irregular cross-sectional shape. In addition, each of the support structures  141  may be formed to exhibit substantially the same horizontal cross-sectional dimensions (e.g., substantially the same horizontal diameter), or at least one of the support structures  141  may be formed to exhibit one or more different horizontal cross-sectional dimensions (e.g., a different horizontal diameter) than at least one other of the support structures  141 . In some embodiments, all of the support structures  141  are formed to exhibit substantially the same horizontal cross-sectional dimensions. 
     The support structures  141  may each individually be formed of and include at least one conductive material, such as one or more of at least one metal (e.g., W, Ti, Mo, Nb, V, Hf, Ta, Cr, Zr, Fe, Ru, Os, Co, Rh, Ir, Ni, Pa, Pt, Cu, Ag, Au, Al), at least one alloy (e.g., a Co-based alloy, an Fe-based alloy, an Ni-based alloy, an Fe- and Ni-based alloy, a Co- and Ni-based alloy, an Fe- and Co-based alloy, a Co- and Ni- and Fe-based alloy, an Al-based alloy, a Cu-based alloy, a Mg-based alloy, a Ti-based alloy, a steel, a low-carbon steel, a stainless steel), at least one conductive metal-containing material (e.g., a conductive metal nitride, a conductive metal silicide, a conductive metal carbide, a conductive metal oxide), and at least one conductively-doped semiconductor material (e.g., conductively-doped Si, conductively-doped Ge, conductively-doped SiGe). In addition, at least one insulative liner material may be formed to substantially surround (e.g., substantially horizontally and vertically cover) side surfaces (e.g., sidewalls) of each of the support structures  141 . The insulative liner material may be horizontally interposed between the support structures  141  and the tiers  138  of the blocks  130  of the stack structure  128 . The insulative liner material may be formed of and include one or more of at least one dielectric oxide material (e.g., one or more of SiO x , phosphosilicate glass, borosilicate glass, borophosphosilicate glass, fluorosilicate glass, AlO x , HfO x , NbO x , TiO x , ZrO x , TaO x , and MgO x ), at least one dielectric nitride material (e.g., SiN y ), at least one dielectric oxynitride material (e.g., SiO x N y ), at least one dielectric carboxynitride material (e.g., SiO x C z N y ), and amorphous carbon. In some embodiments, the insulative liner material comprises SiO 2 . 
     Referring next to  FIG.  5 A , which is a simplified, longitudinal cross-sectional view of the portion A of the microelectronic device structure  100  following the processing stage previously described with reference to  FIGS.  4 A through  4 C , for each block  130  of the stack structure  128 , portions of at least the dielectric fill material  124 , the dielectric structures  122 , and the dielectric liner material  120  are removed (e.g., etched) to form contact openings  144  (e.g., apertures, vias) vertically extending (e.g., in the Z-direction) therethrough. The contact openings  144  may also individual vertically extend through the insulative structure  134  of a tier  138  of the block  130 . The contact openings  144  may vertically extend to or into steps  116  of one or more (e.g., each) of the stadium structures  110 , such as steps  116  of the forward staircase structure  112 A of one or more of the stadium structures  110  and/or steps  116  of the reverse staircase structure  112 B of one or more of the stadium structures  110 . A bottom (e.g., lower vertical end) of each contact opening  144  may expose and be defined by an upper surface of the conductive structures  136  of an individual tier  138  of the stack structure  128  at an individual step  116  of an individual stadium structure  110  of an individual block  130  of the stack structure  128 .  FIG.  5 B  is a simplified, partial longitudinal cross-sectional view of a portion of the microelectronic device structure  100  at the processing stage of  FIG.  5 A  about a dashed line B-B shown in  FIG.  5 A . 
     Within each block  130  of the stack structure  128 , each contact opening  144  may be formed at desired a horizontal position (e.g., in the X-direction and the Y-direction) on or over one of the steps  116  of one of the stadium structures  110 . In some embodiments, within a horizontal area of one or more of the stadium structures  110 , at least some of the contact openings  144  are horizontally offset in the Y-direction from at least some other of the contact openings  144 . In  FIG.  5 A , such horizontal offset is depicted by way of dashed lines at the boundaries (e.g., horizontal boundaries, vertical boundaries) of the contact openings  144 . In addition, individual steps  116  of an individual stadium structure  110  (e.g., individual steps  116  of the forward staircase structure  112 A thereof, individual steps  116  of the reverse staircase structure  112 B thereof) may have a single (e.g., only one) contact opening  144  vertically extending thereto, may have multiple (e.g., more than one) contact openings  144  vertically extending thereto, or may have no contact openings  144  vertically extending thereto. 
     The contact openings  144  may each individually be formed to exhibit a desired horizontal cross-sectional shape. In some embodiments, each of the contact openings  144  is formed to exhibit a substantially circular horizontal cross-sectional shape. In additional embodiments, one or more (e.g., each) of the contact openings  144  exhibits a non-circular cross-sectional shape, such as one more of an oblong cross-sectional shape, an elliptical cross-sectional shape, a square cross-sectional shape, a rectangular cross-sectional shape, a tear drop cross-sectional shape, a semicircular cross-sectional shape, a tombstone cross-sectional shape, a crescent cross-sectional shape, a triangular cross-sectional shape, a kite cross-sectional shape, and an irregular cross-sectional shape. In addition, each of the contact openings  144  may be formed to exhibit substantially the same horizontal cross-sectional dimensions (e.g., substantially the same horizontal diameter), or at least one of the contact openings  144  may be formed to exhibit one or more different horizontal cross-sectional dimensions (e.g., a different horizontal diameter) than at least one other of the contact openings  144 . In some embodiments, all of the contact openings  144  are formed to exhibit substantially the same horizontal cross-sectional dimensions. 
     The contact openings  144  may be formed using multiple material removal acts. For example, portions of the dielectric fill material  124  may be removed using a first material removal act (e.g., a first etching process) to form preliminary contact openings vertically extending to and exposing portions of the dielectric structures  122 ; and then portions of at least the dielectric structures  122  and the dielectric liner material  120  within horizontal boundaries of the preliminary contact openings may be removed using a second material removal act (e.g., a second etching process) to vertically extend the preliminary contact openings to the steps  116  of the stadium structures  110  and form the contact openings  144 . As shown in  FIG.  5 A , depending on the sequence of the conductive structures  136  and the insulative structures  134  of the blocks  130  of the stack structure  128 , the second material removal act extend the preliminary contact openings through insulative structures  134  of tiers  139  of the blocks  130  defining the steps  116  of the stadium structures  110 . As a non-limiting example, the first material removal act may comprise a first etching process (e.g., anisotropic dry etching, such as one or more of RIE, deep RIE, plasma etching, reactive ion beam etching, and chemically assisted ion beam etching); and the second material removal act may comprise a second, different etching process (e.g., a so-called “punch through” etch). During the first etching process, the dielectric structures  122  may serve as a so-called “etch stop” structures to protect underlying portions of the dielectric liner material  120  and the stack structure  128  from removal. 
     Referring next to  FIG.  6 A , which is a simplified, longitudinal cross-sectional view of the portion A of the microelectronic device structure  100  following the processing stage previously described with reference to  FIGS.  5 A and  5 B , contact structures  146  may be formed within the contact openings  144  ( FIGS.  5 A and  5 B ). The contact structures  146  may be substantially confined within boundaries (e.g., horizontal boundaries, vertical boundaries) of the contact openings  144  ( FIGS.  5 A and  5 B ), and may substantially fill the contact openings  144  ( FIGS.  5 A and  5 B ). Each contact structure  146  may have a geometric configuration (e.g., shape, dimensions) corresponding to (e.g., substantially the same as) a geometric configuration of the contact opening  144  ( FIGS.  5 A and  5 B ) filled with the contact structure  146 . As shown in  FIG.  6 A , each contact structure  146  may have an uppermost vertical boundary (e.g., an uppermost surface) substantially coplanar with an uppermost vertical boundary (e.g., an uppermost surface) of the dielectric fill material  124 , and a lowermost vertical boundary (e.g., a lowermost surface) vertically adjacent an uppermost vertical boundary (e.g., an uppermost surface) of the conductive structure  136  of an individual tier  138  of an individual block  130  the stack structure  128 . In additional embodiments, one or more (e.g., each) of the contact structures  146  may have an uppermost vertical boundary offset from (e.g., vertically over, vertically under) an uppermost vertical boundary (e.g., an uppermost surface) of the dielectric fill material  124 . Each contact structure  146  may individually contact (e.g., physically contact, electrically contact) the conductive structure  136  of the individual tier  138  of the stack structure  128  at an individual step  116  of an individual stadium structure  110  of an individual block  130  of the stack structure  128 . 
     The contact structures  146  may be formed of and include conductive material. As a non-limiting example, the contact structures  146  may be formed of and include one or more of at least one metal, at least one alloy, and at least one conductive metal-containing material (e.g., a conductive metal nitride, a conductive metal silicide, a conductive metal carbide, a conductive metal oxide). A material composition of the contact structures  146  may be substantially the same as a material composition of the conductive structures  136  of the tiers  138  of the blocks  130  of the stack structure  128 , or the material composition of the contact structures  146  may be different than the material composition of the conductive structures  136  of the tiers  138  of the blocks  130  of the stack structure  128 . In some embodiments, the contact structures  146  are individually formed of and include W. The contact structures  146  may individually be homogeneous, or the contact structures  146  may individually be heterogeneous. 
     The contact structures  146  may be formed by forming (e.g., non-conformably depositing, such as through one or more of a PVD process and a non-conformal CVD process) conductive material inside and outside of the contact openings  144  ( FIGS.  5 A and  5 B ), and then removing (e.g., through an abrasive planarization process, such as a CMP process) portions of the conductive material overlying an uppermost vertical boundary (e.g., an uppermost surface) of the dielectric fill material  124 . 
     Thus, in accordance with embodiments of the disclosure, a microelectronic device comprises a stack structure comprising blocks separated from one another by dielectric slot structures and each including a vertically alternating sequence of conductive structures and insulative structures arranged in tiers. At least one of the blocks comprises two crest regions, a stadium structure interposed between the two crest regions in a first horizontal direction and comprising opposing staircase structures each having steps comprising edges of the tiers, and two bridge regions neighboring opposing sides of the stadium structure in a second horizontal direction orthogonal to the first horizontal direction and having upper surfaces substantially coplanar with upper surfaces of the two crest region. A filled trench vertically overlies and is within horizontal boundaries of the stadium structure of the at least one of the blocks. The filled trench comprises a dielectric liner material on the opposing staircase structures of the stadium structure and on inner sidewalls of the two bridge regions, and dielectric structures on the dielectric liner material and having a different material composition than the dielectric liner material. The dielectric structures are substantially confined within horizontal areas of the steps of the stadium structure. 
     Furthermore, in accordance with embodiments of the disclosure, a method of forming a microelectronic device comprises forming a preliminary stack structure comprising a vertically alternating sequence of sacrificial material and insulative material arranged in tiers. The preliminary stack structure further comprises rows of stadium structures each comprising at least two of the stadium structures neighboring one another in a first horizontal direction and each comprising opposing staircase structures having steps comprising edges of the tiers of the preliminary stack structure. At least two filled trenches are formed vertically over and within horizontal boundaries of the at least two of the stadium structures of each of the rows of stadium structures. Each of the at least two filled trenches comprises a dielectric liner material on surfaces of the preliminary stack structure, and dielectric structures on the dielectric liner material and substantially confined within horizontal areas of the steps of the opposing staircase structures of one of the at least two of the stadium structures. The preliminary stack structure is divided into blocks separated from one another by slots. Each of the blocks comprises one of the rows of stadium structures, at least one crest region interposed between the at least two of the stadium structures of the one of the rows of stadium structures in the first horizontal direction, and bridge regions integral and continuous with the at least one crest region and neighboring the at least two of the stadium structures in a second horizontal direction orthogonal to the first horizontal direction. The sacrificial material of the preliminary stack structure is replaced with conductive material by way of the slots. 
     Microelectronic device structures (e.g., the microelectronic device structure  100  previously described with reference to  FIGS.  6 A and  6 B ) of the disclosure may be included in microelectronic devices of the disclosure. For example,  FIG.  7    illustrates a partial cutaway perspective view of a portion of a microelectronic device  201  (e.g., a memory device, such as a 3D NAND Flash memory device) including a microelectronic device structure  200 . The microelectronic device structure  200  may be substantially similar to of the microelectronic device structure  100  previously described with reference to  FIGS.  6 A and  6 B . In  FIG.  7    and the associated description, functionally similar features (e.g., structures, materials) are referred to with similar reference numerals incremented by 100. To avoid repetition, not all features shown in  FIG.  7    are described in detail herein. Rather, unless described otherwise below, a feature designated by a reference numeral that is a 100 increment of the reference numeral of a previously described feature will be understood to be substantially similar to the previously described feature. By way of non-limiting example, unless described otherwise below, a feature designated by the reference numeral  226  in  FIG.  7    will be understood to be substantially similar to the filled trenches  126  (including the dielectric liner material  120 , the dielectric structures  122 , and the dielectric fill material  124  thereof) previously described herein with reference to  FIGS.  6 A and  6 B . In addition, for clarity and ease of understanding the drawings and associated description, some features (e.g., structures, materials) of the microelectronic device structure  100  previously described herein are not shown in  FIG.  7   . However, it will be understood that any features of the microelectronic device structure  100  previously described with reference to one or more of  FIGS.  6 A and  6 B  may be included in the microelectronic device structure  200  of the microelectronic device  201  described herein with reference to  FIG.  7   . 
     As shown in  FIG.  7   , in addition to the features of the microelectronic device structure  200  previously described herein in relation to the microelectronic device structure  100  ( FIGS.  6 A and  6 B ), the microelectronic device  201  may further include cell pillar structures  248  vertically extending through each block  230  of the stack structure  228 . The cell pillar structures  248  may be positioned within regions (e.g., memory array regions) of the block  230  horizontally offset (e.g., in the X-direction) from the stadium structures  210  (e.g., the first stadium structure  210 A) (and, hence, the bridge regions  242 ) within the blocks  230 . Intersections of the cell pillar structures  248  and the conductive structures  236  of the tiers  238  of the blocks  230  of stack structure  228  form strings of memory cells  250  vertically extending through each block  230  of the stack structure  202 . For each string of memory cells  250 , the memory cells  250  thereof may be coupled in series with one another. Within each block  230 , the conductive structures  236  of some of the tiers  238  thereof may serve as access line structures (e.g., word line structures) for the strings of memory cells  250  within the horizontal area of the block  230 . In some embodiments, within each block  230 , the memory cells  250  formed at the intersections of the conductive structures  236  of some of the tiers  238  and the cell pillar structures  248  comprise so-called “MONOS” (metal-oxide-nitride-oxide-semiconductor) memory cells. In additional embodiments, the memory cells  250  comprise so-called “TANOS” (tantalum nitride-aluminum oxide-nitride-oxide-semiconductor) memory cells, or so-called “BETANOS” (band/barrier engineered TANOS) memory cells, each of which are subsets of MONOS memory cells. In further embodiments, the memory cells  250  comprise so-called “floating gate” memory cells including floating gates (e.g., metallic floating gates) as charge storage structures. The floating gates may horizontally intervene between central structures of the cell pillar structures  248  and the conductive structures  236  of the different tiers  238  of the stack structure  228 . 
     The microelectronic device  201  may further include at least one source structure  252 , access line routing structures  254 , first select gates  256  (e.g., upper select gates, drain select gates (SGDs)), select line routing structures  258 , one or more second select gates  260  (e.g., lower select gates, source select gate (SGSs)), and digit line structures  262 . The digit line structures  262  may vertically overlie and be coupled to the cell pillar structures  248  (and, hence, the strings of memory cells  250 ). The source structure  252  may vertically underlie and be coupled to the cell pillar structures  248  (and, hence, the strings of memory cells  250 ). In addition, the contact structures  244  may couple various features of the microelectronic device  201  to one another as shown (e.g., the select line routing structures  258  to the first select gates  256 ; the access line routing structures  254  to the conductive structures  236  of the tiers  238  of the blocks  230  of the stack structure  228 ). 
     The microelectronic device  201  may also include a base structure  264  positioned vertically below the cell pillar structures  248  (and, hence, the strings of memory cells  250 ). The base structure  264  may include at least one control logic region including control logic devices configured to control various operations of other features (e.g., the strings of memory cells  250 ) of the microelectronic device  201 . As a non-limiting example, the control logic region of the base structure  264  may further include one or more (e.g., each) of charge pumps (e.g., V CCP  charge pumps, V NEGWL  charge pumps, DVC2 charge pumps), delay-locked loop (DLL) circuitry (e.g., ring oscillators), V dd  regulators, drivers (e.g., string drivers), page buffers, decoders (e.g., local deck decoders, column decoders, row decoders), sense amplifiers (e.g., equalization (EQ) amplifiers, isolation (ISO) amplifiers, NMOS sense amplifiers (NSAs), PMOS sense amplifiers (PSAs)), repair circuitry (e.g., column repair circuitry, row repair circuitry), I/O devices (e.g., local I/O devices), memory test devices, MUX, error checking and correction (ECC) devices, self-refresh/wear leveling devices, and other chip/deck control circuitry. The control logic region of the base structure  264  may be coupled to the source structure  252 , the access line routing structures  254 , the select line routing structures  258 , and the digit line structures  262 . In some embodiments, the control logic region of the base structure  264  includes CMOS (complementary metal-oxide-semiconductor) circuitry. In such embodiments, the control logic region of the base structure  264  may be characterized as having a “CMOS under Array” (“CuA”) configuration. 
     Thus, in accordance with embodiments of the disclosure, a memory device comprises a stack structure, filled trenches, and strings of memory cells. The stack structure comprises tiers each comprising a conductive material and an insulative material vertically neighboring the conductive material. The stack structure is divided into blocks extending in parallel in a first direction and separated from one another in a second direction by dielectric slot structures. Each of the blocks comprises a stadium structure, first elevated regions, and second elevated regions. The stadium structure comprises opposing staircase structures individually having steps comprising horizontal ends of at least some the tiers of the stack structure. The first elevated regions neighbor opposing ends of the stadium structure in the first direction. The second elevated regions neighbor opposing sides of the stadium structure in the second direction. Uppermost surfaces of the second elevated regions are substantially coplanar with uppermost surfaces of the first elevated regions. The filled trenches are within the blocks of the stack structure. Each of the filled trenches is vertically over and within a horizontal area of the stadium structure of one of the blocks of the stack structure. Each of the filled trenches comprises a dielectric liner material on surfaces of the stadium structure, the first elevated regions, and the second elevated regions; dielectric structures on the dielectric liner material and substantially confined within horizontal boundaries of the steps of the stadium structure; and a dielectric fill material over the dielectric structures and the dielectric liner material. The strings of memory cells vertically extend through a portion of each of the blocks neighboring the stadium structure in the first direction. 
     Microelectronic devices structures (e.g., the microelectronic device structure  100  previously described with reference to  FIGS.  6 A and  6 B ) and microelectronic devices (e.g., the microelectronic device  201  ( FIG.  7   )) in accordance with embodiments of the disclosure may be used in embodiments of electronic systems of the disclosure. For example,  FIG.  8    is a block diagram of an illustrative electronic system  303  according to embodiments of disclosure. The electronic system  303  may comprise, for example, a computer or computer hardware component, a server or other networking hardware component, a cellular telephone, a digital camera, a personal digital assistant (PDA), portable media (e.g., music) player, a Wi-Fi or cellular-enabled tablet such as, for example, an iPad® or SURFACE® tablet, an electronic book, a navigation device, etc. The electronic system  303  includes at least one memory device  305 . The memory device  305  may comprise, for example, one or more of a microelectronic device structure (e.g., the microelectronic device structure previously described with reference to  FIGS.  6 A and  6 B ) and a microelectronic device (e.g., the microelectronic device  201  ( FIG.  7   )) previously described herein. The electronic system  303  may further include at least one electronic signal processor device  307  (often referred to as a “microprocessor”). The electronic signal processor device  307  may, optionally, include one or more of a microelectronic device structure (e.g., the microelectronic device structure  100  previously described with reference to  FIGS.  6 A and  6 B ) and a microelectronic device (e.g., the microelectronic device  201  ( FIG.  7   )) previously described herein. While the memory device  305  and the electronic signal processor device  307  are depicted as two (2) separate devices in  FIG.  8   , in additional embodiments, a single (e.g., only one) memory/processor device having the functionalities of the memory device  305  and the electronic signal processor device  307  is included in the electronic system  303 . In such embodiments, the memory/processor device may include one or more of a microelectronic device structure (e.g., the microelectronic device structure  100  previously described with reference to  FIGS.  6 A and  6 B ) and a microelectronic device (e.g., the microelectronic device  201  ( FIG.  7   )) previously described herein. The electronic system  303  may further include one or more input devices  309  for inputting information into the electronic system  303  by a user, such as, for example, a mouse or other pointing device, a keyboard, a touchpad, a button, or a control panel. The electronic system  303  may further include one or more output devices  311  for outputting information (e.g., visual or audio output) to a user such as, for example, a monitor, a display, a printer, an audio output jack, a speaker, etc. In some embodiments, the input device  309  and the output device  311  comprise a single touchscreen device that can be used both to input information to the electronic system  303  and to output visual information to a user. The input device  309  and the output device  311  may communicate electrically with one or more of the memory device  305  and the electronic signal processor device  307 . 
     Thus, in accordance with embodiments of the disclosure, an electronic system comprises an input device, an output device, a processor device operably coupled to the input device and the output device, and a memory device operably coupled to the processor device. The memory device comprises at least one microelectronic device structure comprising a stack structure, filled trenches, and conductive contact structures. The stack structure having a vertically alternating sequence of conductive material and insulative material arranged in tiers. The stack structure comprises at least two blocks separated from one another by at least one dielectric structure. Each of the at least two blocks comprises two elevated regions, a stadium structure, and two additional elevated regions. The stadium structure is interposed between the two elevated regions in a first horizontal direction and comprises staircase structures opposing one another in the first horizontal direction. The staircase structures each have steps comprising edges of the tiers of the stack structure. The two additional elevated regions neighbor opposing sides of the stadium structure in a second horizontal direction perpendicular to the first horizontal direction. The filled trenches are over and within horizontal boundaries of the at least two blocks of the stack structure. Each of the filled trenches comprises a dielectric liner material, dielectric structures, and a dielectric fill material. The dielectric liner material is on surfaces of the stadium structure, the two elevated regions, and the two additional elevated regions of one of the at least two blocks of the stack structure. The dielectric structures are on horizontally extending surfaces of the dielectric liner material and are omitted from vertically extending surfaces of the dielectric liner material. The dielectric fill material is over the dielectric structures and the dielectric liner material. The conductive contact structures vertically extend completely through the filled trenches. 
     The structures, devices, system, and methods of the disclosure advantageously facilitate one or more of improved microelectronic device performance, reduced costs (e.g., manufacturing costs, material costs), increased miniaturization of components, and greater packaging density as compared to conventional structures, conventional devices, conventional systems, and conventional methods. The structures, devices, systems, and methods of the disclosure may also improve scalability, efficiency, and simplicity as compared to conventional structures, conventional devices, conventional systems, and conventional methods. 
     While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, the disclosure is not limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the following appended claims and their legal equivalents. For example, elements and features disclosed in relation to one embodiment of the disclosure may be combined with elements and features disclosed in relation to other embodiments of the disclosure.