Abstract: An alternating stack of first material layers and second material layers is formed over a substrate. A hard mask layer is formed over the alternating stack and cavities are formed in the hard mask layer. A cladding liner is formed on sidewalls of the cavities in the hard mask layer. Via openings are formed through each layer within the alternating stack by performing an anisotropic etch process that transfers a pattern of the cavities through the alternating stack.

Abstract: A memory device, and a method of manufacturing the same, includes interlayer insulation layers spaced apart from each other and stacked, gate lines formed between the interlayer insulation layers, and a plug vertically passing through the interlayer insulation layers and the gate lines. Each of the gate lines includes a barrier layer formed along an inner wall of the interlayer insulation layer and the plug, a first conductive layer surrounded by the barrier layer, and a second conductive layer surrounded by the first conductive layer. A material of the second conductive layer is different from a material of the first conductive layer, and a size of the second conductive layer is variable along a direction in which the gate lines extend.

Abstract: Methods, devices, systems, and apparatus for three-dimensional semiconductor structures are provided. In one aspect, a semiconductor device includes: a semiconductor substrate, multiple conductive layers vertically stacked on the semiconductor substrate, and multiple transistors. The multiple conductive layers include a first conductive layer, a second conductive layer, and a third conductive layer that are sequentially stacked together. The multiple transistors include a first transistor and a second transistor in the first conductive layer and a third transistor in the third conductive layer. Each transistor includes a first terminal, a second terminal, and a gate terminal. First terminals of the first, second, and third transistors are conductively coupled to a first conductive node in the second conductive layer.

Abstract: The present disclosure describes a semiconductor device having a channel structure with profile control. The semiconductor device includes a fin structure on a substrate. The fin structure includes a bottom portion on the substrate and a top portion including multiple semiconductor layers. The semiconductor device further includes a gate structure wrapped around the multiple semiconductor layers and a source/drain (S/D) structure on the bottom portion of the fin structure and in contact with the plurality of semiconductor layers. The S/D structure extends into end portions of the multiple semiconductor layers.

Abstract: A method of forming a semiconductor device includes forming, on a lower structure, a mold structure having interlayer insulating layers and gate layers alternately and repeatedly stacked. Each of the gate layers is formed of a first layer, a second layer, and a third layer sequentially stacked. The first and third layers include a first material, and the second layer includes a second material having an etch selectivity different from an etch selectivity of the first material. A hole formed to pass through the mold structure exposes side surfaces of the interlayer insulating layers and side surfaces of the gate layers. Gate layers exposed by the hole are etched, with an etching speed of the second material differing from an etching speed of the first material, to create recessed regions.

Abstract: A liner is formed laterally-outside of individual channel-material strings in one of first tiers and in one of second tiers. The liners are isotropically etched to form void-spaces in the one second tier above the one first tier. Individual of the void-spaces are laterally-between the individual channel-material strings and the second-tier material in the one second tier. Conductively-doped semiconductive material is formed against sidewalls of the channel material of the channel-material strings in the one first tier and that extends upwardly into the void-spaces in the one second tier. The conductively-doped semiconductive material is heated to diffuse conductivity-increasing dopants therein from the void-spaces laterally into the channel material laterally there-adjacent and upwardly into the channel material that is above the void-spaces.

Abstract: A vertical structure extends through a tiered structure of alternating conductive and insulative materials. The vertical structure includes a channel structure and a tunneling structure. At least one of the conductive materials of the tiered structure provides a select gate tier (e.g., including a control gate for a select gate drain (SGD) transistor). Adjacent the select gate tier of the tiered structure, the tunneling structure consists of or consists essentially of an oxide-only material. Adjacent the word line tiers of the tiered structure, the tunneling structure comprises at least one material that is other than an oxide-only material, such as a nitride or oxynitride. The oxide-only material adjacent the select gate tier may inhibit unintentional loss of charge from a neighboring charge storage structure, which may improve the stability of the threshold voltage (Vth) of the select gate tier.

Abstract: Some embodiments include apparatuses and methods of forming the apparatuses. One of the apparatuses includes a channel to conduct current, the channel including a first channel portion and a second channel portion, a first memory cell structure located between a first gate and the first channel portion, a second memory cell structure located between a second gate and the second channel portion, and a void located between the first and second gates and between the first and second memory cell structures.

Abstract: Embodiments of semiconductor devices and methods for forming the semiconductor devices are disclosed. In an example, a method for forming device openings includes forming a material layer over a first region and a second region of a substrate, the first region being adjacent to the second region, forming a mask layer over the material layer, the mask layer covering the first region and the second region, and forming a patterning layer over the mask layer. The patterning layer covers the first region and the second region and including openings corresponding to the first region. The plurality of openings includes a first opening adjacent to a boundary between the first region and the second region and a second opening further away from the boundary. Along a plane parallel to a top surface of the substrate, a size of the first opening is greater than a size of the second opening.

Abstract: A semiconductor device is provided. The semiconductor device includes a first field effect device on a first region of a substrate, wherein a first gate structure and an electrostatic discharge device on a second region of the substrate, wherein a second gate structure for the electrostatic discharge device is separated from the substrate by the bottom dielectric layer, and a second source/drain for the electrostatic discharge device is in electrical contact with the substrate, wherein the second source/drain is doped with a second dopant type.

Abstract: Embodiments of structure and methods for forming a three-dimensional (3D) memory device are provided. In an example, the memory device includes a stack structure having interleaved a plurality of conductor layers and a plurality of dielectric layers over a substrate along a vertical direction. The memory device also includes a channel structure extending in the stack structure along the vertical direction. A thickness of at least one of the plurality of conductor layers is nominally proportional to a width of the channel structure at the same depth.

Abstract: The present disclosure describes method and structure of a three-dimensional memory device. The memory device includes a substrate and a plurality of wordlines extending along a first direction over the substrate. The first direction is along the x direction. The plurality of wordlines form a staircase structure in a first region. A plurality of channels are formed in a second region and through the plurality of wordlines. The second region abuts the first region at a region boundary. The memory device also includes an insulating slit formed in the first and second regions and along the first direction. A first width of the insulating slit in the first region measured in a second direction is greater than a second width of the insulating slit in the second region measured in the second direction.

Abstract: An embodiment relates to a method and manufacture of robust, high-performance devices. The method comprises preparing a unit cell of a Silicon Carbide (SiC) substrate comprising a first conductivity type substrate and a first conductivity type drift layer; forming a second conductivity type well region; forming a first conductivity type source region within the second conductivity type well region; and forming a second conductivity type shield region surrounding the first conductivity type source region. The second conductivity type shield region formed comprises a portion of the second conductivity type shield region located on a SiC surface.

Abstract: A three-dimensional semiconductor memory device includes a substrate, an electrode structure including gate electrodes sequentially stacked on the substrate, a source structure between the electrode structure and the substrate, vertical semiconductor patterns passing through the electrode structure and the source structure, a data storage pattern between each of the vertical semiconductor patterns and the electrode structure, and a common source pattern between the source structure and the substrate. The common source pattern has a lower resistivity than the source structure and is connected to the vertical semiconductor patterns through the source structure.

Abstract: A device includes a semiconductor substrate having a first region and a second region. The device further includes a first pair of fin structures within the first region. The device further includes a second pair of fin structures within the second region. A top surface of the semiconductor surface between fin structures within the first pair is higher than a top surface of the semiconductor surface between the first pair and the second pair.

Abstract: A method of forming a vertical transport field effect transistor (VTFET) is provided. The method includes forming one or more vertical fins on a substrate, wherein there is a fin transition region between each of the one or more vertical fins and the substrate. The method further includes forming a sidewall liner having a first thickness on each of the one or more vertical fins. The method further includes forming a sidewall spacer having a second thickness on each of the sidewall liner(s), wherein the first thickness of the sidewall liner and the second thickness of the sidewall spacer determines an offset distance from each of the one or more vertical fins. The method further includes forming a trench with an edge offset from each of the one or more vertical fins by the offset distance.

Abstract: Some embodiments include an integrated assembly having a polycrystalline first semiconductor material, and having a second semiconductor material directly adjacent to the polycrystalline first semiconductor material. The second semiconductor material is of a different composition than the polycrystalline first semiconductor material. A conductivity-enhancing dopant is within the second semiconductor material. The conductivity-enhancing dopant is a neutral-type dopant relative to the polycrystalline first semiconductor material. An electrical gate is adjacent to a region of the polycrystalline first semiconductor material and is configured to induce an electric field within said region of the polycrystalline first semiconductor material. The gate is not adjacent to the second semiconductor material.

Abstract: A memory device includes an alternating stack of insulating layers and electrically conductive layers located over a substrate, a memory opening vertically extending through the alternating stack, and a memory opening fill structure located in the memory opening and including a vertical semiconductor channel and a memory material layer. A vertical stack of insulating material portions can be provided at levels of the insulating layers to provide a laterally-undulating profile to the memory material layer. Alternatively, a combination of inner insulating spacers and outer insulating spacers can be employed to provide a laterally-undulating profile to the memory material layer.

Abstract: The present invention relates to a composition for etching, comprising a first inorganic acid, a first additive represented by Chemical Formula 1, and a solvent. The composition for etching is a high-selectivity composition that can selectively remove a nitride film while minimizing the etch rate of an oxide film, and which does not have problems such as particle generation, which adversely affect the device characteristics.

Abstract: A vertical non-volatile memory device includes a channel on a substrate and extending in a first direction perpendicular to an upper surface of the substrate, a first charge storage structure on an outer sidewall of the channel, a second charge storage structure on an inner sidewall of the channel, first gate electrodes spaced apart from each other in the first direction on the substrate, each which surrounds the first charge storage structure, and a second gate electrode on an inner sidewall of the second charge storage structure.

Abstract: A method for forming a mask layer above a semiconductor fin structure is disclosed. In one aspect the method includes forming a first set of spacers and a second set of spacers arranged at the side surfaces of the first set of spacers, providing a first filler material between the second set of spacers, etching a top portion of the first filler material to form recesses between the second set of spacers, and providing a second filler material in the recesses, the second filler material forming a set of sacrificial mask lines. Further, the method includes recessing a top portion of at least the first set of spacers, providing a mask layer material between the sacrificial mask lines, and removing the sacrificial mask lines and the first filler material.

Abstract: A vertical semiconductor device and a method for fabricating the same may include forming an alternating stack of dielectric layers and sacrificial layers over a lower structure, forming an opening by etching the alternating stack, forming a non-conformal blocking layer on the alternating stack in which the opening is formed, adsorbing a deposition inhibitor on a surface of the blocking layer to convert the non-conformal blocking layer into a conformal blocking layer on which the deposition inhibitor is adsorbed, and forming a charge storage layer on the conformal blocking layer.

Abstract: In a method of manufacturing a vertical memory device, a first sacrificial layer including a nitride is formed on a substrate. A mold including an insulation layer and a second sacrificial layer alternately and repeatedly stacked on the first sacrificial layer is formed. The insulation layer and the second sacrificial layer include a first oxide and a second oxide, respectively. A channel is formed through the mold and the first sacrificial layer. An opening is formed through the mold and the first sacrificial layer to expose an upper surface of the substrate. The first sacrificial layer is removed through the opening to form a first gap. A channel connecting pattern is formed to fill the first gap. The second sacrificial layer is replaced with a gate electrode.

Abstract: A nitride semiconductor device includes a nitride semiconductor layer, channel cells in the nitride semiconductor layer, a source lead region of a second conductivity type in the nitride semiconductor layer, and a source electrode on a side where a first main surface of the nitride semiconductor layer is located. The channel cells each include a well region of a first conductivity type and a source region of the second conductivity type in contact with the well region. The source lead region is connected to the source region. The channel cells extend in a first direction in a planar view from a normal direction of the first main surface, and arranged in a second direction intersecting with the first direction in the planar view. The source electrode is in contact with the source lead region away from a line of the channel cells arranged in the second direction.

Abstract: The present disclosure provides an improved field effect transistor and device that can be used to sense and characterize a variety of materials. The field effect transistor and/or device including the transistor may be used for a variety of applications, including genome sequencing, protein sequencing, biomolecular sequencing, and detection of ions, molecules, chemicals, biomolecules, metal atoms, polymers, nanoparticles and the like.

Abstract: An embodiment relates to a method and manufacture of robust, high-performance devices. The method comprises preparing a unit cell of a Silicon Carbide (SiC) substrate comprising a first conductivity type substrate and a first conductivity type drift layer; forming a second conductivity type well region; forming a first conductivity type source region within the second conductivity type well region; and forming a second conductivity type shield region surrounding the first conductivity type source region. The second conductivity type shield region formed comprises a portion of the second conductivity type shield region located on a SiC surface.

Abstract: A vertical transport fin field effect transistor (VT FinFET), including one or more vertical fins on a surface of a substrate, an L-shaped or U-shaped spacer trough on the substrate adjacent to at least one of the one or more vertical fins, and a gate dielectric layer on the sidewalls of the at least one of the one or more vertical fins and the L-shaped or U-shaped spacer trough.

Abstract: A semiconductor device includes a substrate, a plurality of nanowires, and a gate stack. The nanowires are over the substrate. Each of the nanowires includes a channel region, the channel region having top and bottom surfaces and a first sidewall between the top and bottom surfaces, in which the first sidewall of the channel region has a (111) crystalline orientation. The gate stack is over the channel regions of the nanowires.

Abstract: A manufacturing method for a semiconductor device, and an integrated semiconductor device. The manufacturing method comprises: on a semiconductor substrate, forming an epitaxial layer having a first region, a second region, and a third region; forming at least one groove in the third region, forming at least two second doping deep traps in the first region, and forming at least two second doping deep traps in the second region; forming a first dielectric island between the second doping deep traps and forming a second dielectric island on the second doping deep traps; forming a first doping groove at both sides of the first dielectric island in the first region; forming a gate structure on the first dielectric island; forming an isolated first doping source region using the second dielectric island as a mask.

Abstract: A semiconductor and a method of forming a semiconductor on a single chip, including forming a shallow trench isolation (STI) region on a short channel device and a long channel device, forming at least two vertical fins connected in the long channel device, and forming contacts on a source and drain regions for the long channel device and short channel device, wherein the contacts connect a top surface of the source or drain region for series FET (Field-Effect Transistor) connection for the long channel device.

Abstract: A method for fabricating a silicon carbide semiconductor device includes providing a SiC epitaxial layer disposed over a surface of a SiC substrate, forming an implant aperture in a hardmask layer on a surface of the expitaxial SiC layer, implanting contact and well regions in the SiC epitaxial layer through the hardmask layer, the contact region lying completely within and recessed from edges of the well region by performing one of implanting the well region through the implant aperture, reducing the area of the implant aperture forming a reduced-area contact implant aperture and implanting the contact region through the reduced-area implant aperture to form a contact region, and implanting the contact region through the implant aperture, increasing the area of the implant aperture to form a increased-area well implant aperture and implanting the well region through the increased-area implant aperture to form a well region completely surrounding the contact region.

Abstract: A vertical structure extends through a tiered structure of alternating conductive and insulative materials. The vertical structure includes a channel structure and a tunneling structure. At least one of the conductive materials of the tiered structure provides a select gate tier (e.g., including a control gate for a select gate drain (SGD) transistor). Adjacent the select gate tier of the tiered structure, the tunneling structure consists of or consists essentially of an oxide-only material. Adjacent the word line tiers of the tiered structure, the tunneling structure comprises at least one material that is other than an oxide-only material, such as a nitride or oxynitride. The oxide-only material adjacent the select gate tier may inhibit unintentional loss of charge from a neighboring charge storage structure, which may improve the stability of the threshold voltage (Vth) of the select gate tier.

Abstract: Techniques for forming RRAM cells with increased density are provided. In one aspect, a method of forming a RRAM device includes: providing an underlayer disposed on a substrate; patterning trenches in the underlayer; forming bottom electrodes at two different levels of the underlayer that includes first bottom electrodes at bottoms of the trenches and second bottom electrodes along a top surface of the underlayer in between the trenches; depositing an insulating layer on the first/second bottom electrodes; and forming top electrodes on the insulating layer, wherein the top electrodes include word lines, wherein the first and second bottom electrodes include bit lines that are orthogonal to the word lines. A RRAM device is also provided.

Abstract: Provided is a silicon nitride layer etching composition, and more specifically, a silicon nitride layer etching composition including two different silicon-based compounds in an etching composition to be capable of selectively etching a silicon nitride layer relative to a silicon oxide layer with a remarkable etch selectivity ratio and providing remarkable effects of suppressing generation of precipitates and reducing the abnormal growth of other layers existing in the vicinity, including the silicon oxide layer when the silicon nitride layer etching composition is used for an etching process and a semiconductor manufacturing process.

Abstract: A method includes forming a mask layer over a target layer. A first etching process is performed on the mask layer to form a first opening and a second opening in the mask layer. A second etching process is performed on the mask layer to reduce an end-to-end spacing between the first opening and the second opening. The first etching process and the second etching process have different anisotropy properties. A pattern of the mask layer is transferred to the target layer.

Abstract: A semiconductor device includes a semiconductor layer made of a wide bandgap semiconductor and including a gate trench; a gate insulating film formed on the gate trench; and a gate electrode embedded in the gate trench to be opposed to the semiconductor layer through the gate insulating film. The semiconductor layer includes a first conductivity type source region; a second conductivity type body region; a first conductivity type drift region; a second conductivity type first breakdown voltage holding region; a source trench passing through the first conductivity type source region and the second conductivity type body region from the front surface and reaching a drain region; and a second conductivity type second breakdown voltage region selectively formed on an edge portion of the source trench where the sidewall and the bottom wall thereof intersect with each other in a parallel region of the source trench.

Abstract: A method of etching a substrate includes generating plasma comprising a first concentration of an etchant and a second concentration of an inhibitor and etching the substrate by exposing an exposed interface between a first material and a second material to the plasma. The first material includes a lower reactivity to both the etchant and the inhibitor than the second material. The first concentration is less than the second concentration. Etching the substrate includes etching the first material and the second material at the exposed interface to form an etched indentation including an enriched region of the second material, forming a passivation layer at the enriched region using the inhibitor, and etching the first material at the etched indentation. The passivation layer reduces an etch rate of the second material to a reduced rate that is less than an etch rate of the first material.

Abstract: A transistor comprising a channel region on a material is disclosed. The channel region comprises a two-dimensional material comprising opposing sidewalls and oriented perpendicular to the material. A gate dielectric is on the two-dimensional material and gates are on the gate dielectric. Semiconductor devices and systems including at least one transistor are disclosed, as well as methods of forming a semiconductor device.

Abstract: In one embodiment, a semiconductor device includes a first substrate, and a plurality of electrode layers provided above the first substrate and stacked in a first direction. The device further includes a first semiconductor layer extending in the first direction in the plurality of electrode layers, and a metal layer provided above an uppermost one of the plurality of electrode layers and extending to cross the first direction. The device further includes a second semiconductor layer including an impurity diffusion layer that is provided between the first semiconductor layer and the metal layer, electrically connects the first semiconductor layer with the metal layer, and has an impurity concentration higher than an impurity concentration of the first semiconductor layer.

Abstract: Embodiments of the invention are directed to a method that includes forming a fin over a major surface of a substrate. The fin includes an active fin region having a top fin surface and a fin sidewall. The top fin surface is substantially parallel with respect to the major surface, and the fin sidewall is substantially perpendicular with respect to the major surface. A gate is formed over and around a central portion of the fin, the gate having a bottom gate region and a top gate region. The bottom gate region is substantially below the top fin surface and includes a bottom gate region sidewall that is substantially parallel with respect to the fin sidewall. The top gate region is substantially above the top fin surface and includes a top gate region sidewall that is at an angle with respect to the major surface.

Abstract: A method used in forming a memory array comprises forming a conductive tier atop a substrate, with the conductive tier comprising openings therein. An insulator tier is formed atop the conductive tier and the insulator tier comprises insulator material that extends downwardly into the openings in the conductive tier. A stack comprising vertically-alternating insulative tiers and wordline tiers is formed above the insulator tier. Strings comprising channel material that extend through the insulative tiers and the wordline tiers are formed. The channel material of the strings is directly electrically coupled to conductive material in the conductive tier. Structure independent of method is disclosed.

Abstract: Some embodiments include an integrated assembly having a polycrystalline first semiconductor material, and having a second semiconductor material directly adjacent to the polycrystalline first semiconductor material. The second semiconductor material is of a different composition than the polycrystalline first semiconductor material. A conductivity-enhancing dopant is within the second semiconductor material. The conductivity-enhancing dopant is a neutral-type dopant relative to the polycrystalline first semiconductor material. An electrical gate is adjacent to a region of the polycrystalline first semiconductor material and is configured to induce an electric field within said region of the polycrystalline first semiconductor material. The gate is not adjacent to the second semiconductor material.

Abstract: A three dimensional flash memory element with middle source-drain line and manufacturing method thereof. The three dimensional flash memory element includes a string including a channel layer extended in one direction and a plurality of electrode layers vertically layered for the channel layer; an upper wiring layer placed at the top of the string; at least one intermediate wiring layer placed between the plurality of electrode layers in the intermediate area of the string; and a lower wiring layer placed at the bottom of the string. Each of the upper wiring layer, the at least one intermediate wiring layer, and the lower wiring layer is adaptively used as any one of a drain electrode or a source electrode.

Abstract: A MOS transistor with two vertical gates is formed within a substrate zone of a semiconductor substrate doped with a first type of conductivity and separated from a remaining portion of the substrate by two first parallel trenches extending in a first direction. An isolated gate region rests on each flank of the substrate zone and on a portion of the bottom of the corresponding trench to form the two vertical gates. At least one gate connection region electrically connects the two vertical gates. A first buried region located under the substrate zone is doped with a second type of conductivity to form a first conduction electrode of the MOS transistor. A second region doped with the second type of conductivity is located at the surface of the substrate zone to form a second conduction electrode of the MOS transistor.

Abstract: A three-dimensional semiconductor memory device includes a substrate, an electrode structure including gate electrodes sequentially stacked on the substrate, a source structure between the electrode structure and the substrate, vertical semiconductor patterns passing through the electrode structure and the source structure, a data storage pattern between each of the vertical semiconductor patterns and the electrode structure, and a common source pattern between the source structure and the substrate. The common source pattern has a lower resistivity than the source structure and is connected to the vertical semiconductor patterns through the source structure.

Abstract: A method of fabricating a vertical fin field effect transistor with a merged top source/drain, including, forming a source/drain layer at the surface of a substrate, forming a plurality of vertical fins on the source/drain layer; forming protective spacers on each of the plurality of vertical fins, forming a sacrificial plug between two protective spacers, forming a filler layer on the protective spacers not in contact with the sacrificial plug, and selectively removing the sacrificial plug to form an isolation region trench between the two protective spacers.

Abstract: Semiconductor structures are provided. Each of the transistors includes a first source/drain region over a semiconductor fin extending in a first direction, a second source/drain region over the semiconductor fin, a channel region in the semiconductor fin and between the first and second source/drain regions, and a metal gate electrode formed on the channel region and extending in a second direction perpendicular to the first direction. In a first transistor of the transistors, a first source/drain region is formed between the metal gate electrode of the first transistor and the metal gate electrode of a second transistor of the transistors, A second source/drain region is formed between the metal gate electrode of the first transistor and the dielectric-base dummy gate extending in the second direction. A first contact of the first source/drain region is narrower than a second contact of the second source/drain region along the first direction.

Abstract: The disclosed technology generally relates to semiconductor fabrication, and more particularly to a method of forming a target layer surrounding a vertical nanostructure. In one aspect, a method includes providing a substrate having a substrate surface. The method additionally includes forming a vertical nanostructure extending outwardly from a substrate surface. The vertical nanostructure has a sidewall surface, where the sidewall surface has an upper portion and a lower portion. The method additionally includes forming a target layer at least along the sidewall surface of the vertical nanostructure and on the substrate surface. The method additionally includes forming a protection layer covering the target layer and removing an upper portion of the protection layer, thereby exposing the target layer along the upper portion of the sidewall surface of the vertical nanostructure.

Abstract: A method of forming a semiconductor device comprises patterning a mask material adjacent to an array of transistors, forming an electrically conductive material between adjacent portions of the patterned mask material, forming an additional mask material over the patterned mask material to form a mask structure, the additional mask material having an arcuate cross-sectional shape, removing a portion of the additional mask material to reduce a spacing between adjacent portions of the additional mask material, and forming capacitor structures in openings between the mask structure. Additional methods of forming a semiconductor device, and related semiconductor devices and related systems are also disclosed.

Abstract: A vertical memory device includes a substrate including a cell array region and a staircase region surrounding the cell array region, gate electrodes on the cell array region and the staircase region, and a channel on the cell array region. The gate electrodes are isolated from each other in first and third directions and each extend in a second direction. The channel extends in the first direction through one or more gate electrodes. End portions in the second direction of first gate electrodes of the plurality of gate electrodes define first steps in the second direction and second steps in the third direction on the staircase region of the substrate, the second steps being connected to the first steps, respectively, at same levels.