Abstract: Monolithic three-dimensional NAND memory strings and methods of fabricating a monolithic three-dimensional NAND memory string include forming single crystal or large grain polycrystalline semiconductor material charge storage regions by a metal induced crystallization process. In another embodiment, a plurality of front side recesses are formed having a concave-shaped surface and a blocking dielectric and charge storage regions are formed within the front side recesses and over the concave-shaped surface. In another embodiment, layers of oxide material exposed in a front side opening of a material layer stack are surface nitrided and etched to provide convexly-rounded corner portions, and a blocking dielectric is formed over the convexly-rounded corner portions.

Abstract: A memory stack structure can be formed through a stack of an alternating plurality of first material layers and second material layers and through an overlying temporary material layer having a different composition than the first and second material layers. The memory stack structure can include a memory film and a semiconductor channel layer. The overlying temporary material layer is removed selective to the stack to form a lateral recess. Portions of the memory film are removed around the lateral recess, and dopants are laterally introduced into an upper portion of the semiconductor channel to form a self-aligned drain region.

Abstract: A memory film layer is formed in a memory opening through an alternating stack of first material layers and second material layers. A sacrificial material layer is deposited on the memory film layer. Horizontal portions of the sacrificial material layer and the memory film layer at the bottom of the memory opening is removed by an anisotropic etch to expose a substrate underlying the memory opening, while vertical portions of the sacrificial material layer protect vertical portions of the memory film layer. After removal of the sacrificial material layer selective to the memory film, a doped semiconductor material layer can be formed directly on the exposed material in the memory opening and on the memory film as a single material layer to form a semiconductor channel of a memory device.

Abstract: A first stack of alternating layers including first electrically conductive layers and first electrically insulating layers is formed with first stepped surfaces and a first dielectric material portion thereupon. Dielectric pillar structures including a dielectric metal oxide can be formed through the first stepped surfaces. Lower memory openings can be formed, and filled with a disposable material or a lower memory opening structure including a lower semiconductor channel and a doped semiconductor region. At least one dielectric material layer and a second stack of alternating layers including second electrically conductive layers and second electrically insulating layers can be sequentially formed. Upper memory openings can be formed through the second stack and the at least one dielectric material layer. A memory film and a semiconductor channel can be formed after removal of the disposable material, or an upper semiconductor channel can be formed on the doped semiconductor region.

Abstract: A method of making a monolithic three dimensional NAND string including forming a stack of alternating layers of a first material and a second material different from the first material over a substrate, forming an at least one opening in the stack, forming at least a portion of a memory film in the at least one opening and forming a first portion of a semiconductor channel followed by forming a second portion of the semiconductor channel in the at least one opening. The second portion of the semiconductor channel comprises silicon and germanium and contains more germanium than a first portion of the semiconductor channel which is located closer to the memory film than the second portion.

Abstract: Techniques are provided for fabricating a three-dimensional, charge-trapping memory device with improved long term data retention. A corresponding three-dimensional, charge-trapping memory device is also provided which includes a stack of alternating word line layers and dielectric layers. A charge-trapping layer is deposited in a memory hole. The refractive index of portions of the charge-trapping layer which are adjacent to the word line layers is increased relative to the refractive index of portions of the charge-trapping layer which are adjacent to the dielectric layers. This can be achieved by doping the portions of the charge-trapping layer which are adjacent to the word line layers. In one approach, the charge-trapping layer is SiON and is doped with Si or N. In another approach, the charge-trapping layer is HfO and is doped with Hf. In another approach, the charge-trapping layer is HfSiON and is doped with Hf, Si or N.

Abstract: A structure includes a three-dimensional semiconductor device including a plurality of unit device structures located over a substrate. Each of the unit device structures includes a semiconductor channel including at least a portion extending vertically along a direction perpendicular to a top surface of the substrate, and a drain region contacting a top end of the semiconductor channel. The structure also includes a combination of a plurality of contact pillars and a contiguous volume that laterally surrounds the plurality of contact pillars. The plurality of contact pillars is in contact with the drain regions, and the contiguous volume has a dielectric constant less than 3.9.

Abstract: A method of making a monolithic three dimensional NAND device includes forming a stack of alternating layers of a first material and a second material different from the first material over a substrate, forming a mask layer over the stack and patterning the mask layer to form at least on opening in the mask layer to expose a top layer of the stack. The method also includes forming a metal block in the at least one opening in the mask layer, etching the stack by metal induced localized etch using the metal block in the at least one opening in the mask layer to form at least one opening in the stack and forming at least one layer of the NAND device in the at least one opening.

Abstract: Disclosed herein are 3D NAND memory devices having vertical NAND strings with a crystalline silicon channel and techniques for fabricating the same. The NAND string channel may be a single crystal of silicon or have a few large grains of polysilicon. The single crystal may have a (100) orientation with respect to a tunnel oxide of the 3D NAND string. When the channel region comprises grains of polysilicon, predominantly all of the silicon channel is part of a grain of polysilicon having the (100) orientation. The (100) orientation may be favorable for high carrier mobility. Techniques using metal induced crystallization (MIC) for forming the NAND strings having a crystalline silicon channel are also disclosed.

Abstract: A memory cell can be formed with a pair of charge storage regions. The pair of charge storage regions can be two portions of a charge storage region that are located at the same level and are positioned adjacent to two different control gate electrodes. Alternately, the pair of charge storage regions can be two disjoined structures located on opposite sides of a portion of a semiconductor channel. Yet alternately, the pair of charge storage regions can be two disjoined structures located at the same level, and on two laterally split semiconductor channel. The memory cell can be employed to store two bits of information within the pair of charge storage regions located at the same level within a vertical memory string that employs a single memory opening.

Abstract: For a non-volatile memory device having a NAND type of architecture, techniques are presented for determining NAND strings that are slow to program. These techniques are particularly applicable to memory devices have a 3D structure, such as of BiCS type, where the slow programming can arise from defects of the spacing between the memory holes, in which the NAND strings are formed, and the local interconnects, such as for connecting common source lines and which run in a vertical direction between groups of NAND strings. The slow to program NAND strings can be recorded and this information can be used when writing data to the NAND strings. Several methods of writing data along a word line that includes such slow to program cells are described.

Abstract: A method of making a monolithic three dimensional NAND string includes forming a stack of alternating first and second material layers over a substrate, etching the stack to form a front side opening, partially removing the second material layers through the front side opening to form front side recesses, forming a first blocking dielectric in the front side recesses, forming charge storage regions over the first blocking dielectric in the front side recesses, forming a tunnel dielectric layer and a semiconductor channel over the charge storage regions in the front side opening, etching the stack to form a back side opening, removing the second material layers through the back side opening to form back side recesses using the first blocking dielectric as an etch stop, forming a second blocking dielectric in the back side recesses, and forming control gates over the second blocking dielectric in the back side recesses.

Abstract: In a three-dimensional stacked non-volatile memory device, a short circuit in a select gate layer is detected and prevented. A short circuit may occur when charges which are accumulated in select gate lines due to plasma etching, discharge through a remaining portion of the select gate layer in a short circuit path when the select gate lines are driven. To detect a short circuit, during a testing phase, an increasing bias is applied is applied to the remaining portion while a current is measured. An increase in the current above a threshold indicates that the bias has exceed a breakdown voltage of a short circuit path. A value of the bias at this time is recorded as an optimal bias. During subsequent operations involving select gate transistors or memory cells, such as programming, erasing or reading, the optimal bias is applied when the select gate lines are driven to prevent a current flow through the short circuit.

Abstract: A number of techniques for determining bit line related defects in non-volatile memory arrays are presented, which are particularly applicable to 3D NAND memory, such as that of the BiCS type. Defects related to bit line to NAND string contacts are determined by application of an AC stress mode along bit lines, followed by a defect detection operation. If the AC stress is applied to be out of phase on adjacent bit lines, this can also be used to accelerate bit line to bit line defects. The subsequent defect determination phase can include an erase operation followed a read to determine whether the NAND strings of the erased block read as erased, a process that can also be followed by a program and subsequent read to further check for defects.

Abstract: In a three-dimensional stacked non-volatile memory device, a short circuit in a select gate layer is detected and prevented. A short circuit may occur when charges which are accumulated in select gate lines due to plasma etching, discharge through a remaining portion of the select gate layer in a short circuit path when the select gate lines are driven. To detect a short circuit, during a testing phase, an increasing bias is applied is applied to the remaining portion while a current is measured. An increase in the current above a threshold indicates that the bias has exceed a breakdown voltage of a short circuit path. A value of the bias at this time is recorded as an optimal bias. During subsequent operations involving select gate transistors or memory cells, such as programming, erasing or reading, the optimal bias is applied when the select gate lines are driven to prevent a current flow through the short circuit.

Abstract: Methods of making a monolithic three dimensional NAND string may enable selective removal of a blocking dielectric material, such as aluminum oxide, without otherwise damaging the device. Blocking dielectric may be selectively removed from the back side (e.g., slit trench) and/or front side (e.g., memory opening) of the NAND string. Also disclosed are NAND strings made in accordance with the embodiment methods.

Abstract: A method of fabricating a semiconductor device, such as a three-dimensional NAND memory string, includes forming a first stack of alternating layers of a first material and a second material different from the first material over a substrate, removing a portion of the first stack to form a first trench, filling the trench with a sacrificial material, forming a second stack of alternating layers of the first material and the second material over the first stack and the sacrificial material, removing a portion of the second stack to the sacrificial material to form a second trench, and removing the sacrificial material to form a continuous trench through the first stack and the second stack.

Abstract: A first stack of alternating layers including first electrically conductive layers and first electrically insulating layers is formed with first stepped surfaces and a first dielectric material portion thereupon. Dielectric pillar structures including a dielectric metal oxide can be formed through the first stepped surfaces. Lower memory openings can be formed, and filled with a disposable material or a lower memory opening structure including a lower semiconductor channel and a doped semiconductor region. At least one dielectric material layer and a second stack of alternating layers including second electrically conductive layers and second electrically insulating layers can be sequentially formed. Upper memory openings can be formed through the second stack and the at least one dielectric material layer. A memory film and a semiconductor channel can be formed after removal of the disposable material, or an upper semiconductor channel can be formed on the doped semiconductor region.

Abstract: In a three-dimensional stacked non-volatile memory device, a short circuit is prevented in a select gate layer by providing a protective material such as a diode, capacitor, linear resistor or varistor between select gate lines and a remaining portion of the select gate layer. Charges which are accumulated in the select gate lines due to plasma etching are therefore prevented from discharging through the remaining portion in a short circuit path when the select gate lines are driven. The protective material can comprise a p-n diode, an n-i-n or p-i-p resistor, a thin oxide layer between doped polysilicon layers in a capacitor, or a variable-resistance material such as ZnO2 between oxide layers in a varistor.

Abstract: A memory film layer is formed in a memory opening through an alternating stack of first material layers and second material layers. A sacrificial material layer is deposited on the memory film layer. Horizontal portions of the sacrificial material layer and the memory film layer at the bottom of the memory opening is removed by an anisotropic etch to expose a substrate underlying the memory opening, while vertical portions of the sacrificial material layer protect vertical portions of the memory film layer. After removal of the sacrificial material layer selective to the memory film, a doped semiconductor material layer can be formed directly on the exposed material in the memory opening and on the memory film as a single material layer to form a semiconductor channel of a memory device.