The present application claims priority under 35 U.S.C. § 119(a) to Korean patent application number 10-2022-0090104, filed on Jul. 21, 2022, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference.
The present disclosure generally relates to a non-volatile memory device, and more particularly, to a three-dimensional non-volatile memory device.
According to the tendency of a decrease in design rule and an increase in degree of integration, studies on non-volatile memory device structures capable of guaranteeing structural stability and reliability of a signal storing operation have been continuously conducted. That is, a technique for increasing the degree of integration of memory cells through a decrease in memory cell area and a technique for improving reliability of stored information by preventing signal interference between adjacent memory cells have been researched.
In accordance with an embodiment of the present disclosure, there may be provided a non-volatile memory device including: a substrate; a gate structure including a plurality of gate electrode layers and a plurality of interlayer insulating layers, which are alternately stacked in a vertical direction over the substrate, the gate structure including a hole pattern; a data storage layer disposed inside the hole pattern; and a channel layer disposed on the data storage layer inside the hole pattern, wherein the channel layer is disposed at each of different levels isolated from each other in the vertical direction by the plurality of interlayer insulating layers.
In accordance with an embodiment of the present disclosure, there may be provided a non-volatile memory device including: a gate structure including a plurality of gate electrode layers and a plurality of interlayer insulating layers, which are alternately stacked in a vertical direction over a substrate; a channel layer disposed on the substrate, the channel layer disposed adjacent to each of the plurality of gate electrode layers of the gate structure; a data storage layer disposed between each of the plurality of gate electrode layers and the channel layer; and a first source/drain pillar and a second source/drain pillar, penetrating the gate structure, wherein each of the data storage layer and the channel layer is discontinuous in the vertical direction, each of the data storage layer and the channel layer being formed at levels in which each of the plurality of gate electrode layers is formed.
Various examples of embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be enabling to those skilled in the art.
In the drawing figures, dimensions may be exaggerated for clarity of illustration. It will be understood that when an element is referred to as being “between” two elements, it may be the only element between the two elements, or additional intervening elements may also be present. Like reference numerals refer to like elements throughout the drawings.
Specific structural and functional descriptions disclosed herein are merely illustrative for the purpose of describing embodiments according to the concept of the present disclosure. Embodiments according to the concept of the present disclosure can be implemented in various forms, and they should not be construed as being limited to the specific embodiments set forth herein.
It will be understood that, although the terms “first”, “second”, etc. may be used herein to describe various elements, these elements are not limited by these terms. These terms are used for distinguishing one element from another element and not to suggest a number or order of elements.
Embodiments provide a non-volatile memory device including memory cells stacked in a three-dimensional structure.
Referring to
The gate structure 110 may include a plurality of gate electrode layers 203 and a plurality of interlayer insulating layers 105, which are alternately stacked in a Z direction over the substrate 100. The Z direction may be a vertical direction with respect to the substrate 100. The plurality of gate electrode layers 203 may include first to fourth gate electrode layers 203a, 203b, 203c, and 203d. Hereinafter, for convenience of description, a structure of the non-volatile memory device is described based on an embodiment including the first to fourth gate electrode layers 203a, 203b, 203c, and 203d. However, in the embodiment of the present disclosure, the number of gate electrode layers is not limited to 4 and may vary based on the embodiment.
The gate structure 110 may include a plurality of hole patterns 107, and the plurality of hole patterns 107 may be disposed while being spaced apart from each other. The non-volatile memory device may include memory units that are distinguished from each other for each hole pattern 107. The memory units that are distinguished from each other for each hole pattern 107 may be independently driven. The plurality of hole patterns 107 may be arranged in various structures. In an embodiment, the plurality of hole patterns 107 may be arranged in zigzag in the gate electrode layer 203. The planar shape of the plurality of hole patterns 107 may vary based on the embodiment. In an embodiment, as shown in the drawings, the plurality of hole patterns 107 may have a circular shape. In another embodiment, although not shown in the drawings, the plurality of hole patterns 107 may have an elliptical or polygonal planar shape.
The data storage layer 111 may be disposed to be discontinuous in the Z direction. More specifically, the data storage layer 111 may include first to fourth memory parts 111A, 111B, 111C, and 111D, which are formed at four different levels. The levels at which the first to fourth memory parts 111A, 111B, 111C, and 111D are formed may respectively coincide with levels at which the first to fourth gate electrode layers 203a, 203b, 203c, and 203d are formed. In other words, each memory part may be formed on the same level as the corresponding gate electrode layer. Each of the first to fourth memory parts 111A, 111B, 111C, and 111D may cover a sidewall surface of a corresponding gate electrode layer, among the first to fourth gate electrode layers 203a, 203b, 203c, and 203d.
The channel layer 113 may be disposed to be discontinuous in the Z direction. More specifically, the channel layer 113 may include first to fourth cell parts 113A, 113B, 113C, and 113D, which are formed at four different levels. The levels at which the first to fourth cell parts 113A, 113B, 113C, and 113D are formed may respectively coincide with the levels at which the first to fourth gate electrode layers 203a, 203b, 203c, and 203d are formed. In other words, each cell part may be formed on the same level as the corresponding gate electrode layer. The first to fourth cell parts 113A, 113B, 113C, and 113D may be disposed to be in contact with the first to fourth memory parts 111A, 111B, 111C, and 111D. In other words, the channel layer 113 may be disposed to be in contact with the data storage layer 111, and the data storage layer 111 may be disposed between the channel layer 113 and the gate electrode layer 203.
Each of the data storage layer 111 and the channel layer 113 may be discontinuous in the Z direction. More specifically, the plurality of interlayer insulating layers 105 may protrude farther into the hole pattern 107 compared to the plurality of gate electrodes 203 (i.e., the first to fourth gate electrode layers 203a, 203b, 203c, and 203d in the embodiment). The hole pattern 107 may include a plurality of concave parts that are defined at the same levels as the plurality of gate electrode layers 203. Each concave part may be defined between a plurality of interlayer insulating layers 105 that overlap with each other in the Z direction. Specifically, the plurality of interlayer insulating layers 105 may include a first interlayer insulating layer and a second interlayer insulating layer, which are adjacent to each other in the Z direction, and the concave part may be defined between the first interlayer insulating layer and the second interlayer insulating layer. Each of the data storage layer 111 and the channel layer 113 may be disposed at the concave part between the first interlayer insulating layer and the second interlayer insulating layer. In other words, the first to fourth cell parts 113A, 113B, 113C, and 113D may be respectively disposed at different levels, isolated from each other in the Z direction by the plurality of interlayer insulating layers 105, and the first to fourth memory parts 111A, 111B, 111C, and 111D may be respectively disposed at different levels, isolated from each other in the Z direction by the plurality of interlayer insulating layers 105.
The data storage layer 111 may be a ferroelectric memory layer. That is, the data storage layer 111 may include ferroelectrics. The ferroelectrics may be a material having a spontaneous electrical polarization in a state in which no external electric field is applied.
In an embodiment, the ferroelectrics may represent polarization hysteresis behavior including a switching operation of the electrical polarization when an external electric field is applied. After the external electric field is removed, the ferroelectrics may maintain, in a non-volatile manner, any one of two stabilized residual polarizations that are generated as a result of the polarization hysteresis behavior. The two stabilized residual polarizations may have different polarization orientations. Such a residual polarization characteristic may be used to store signal information of “0” and “1” in the non-volatile manner. The ferroelectrics may be, for example, hafnium oxide, zirconium oxide, hafnium zirconium oxide, or any combination of two or more thereof.
The non-volatile memory device may include a first insulating pillar 122, a second insulating pillar 126, a first source/drain pillar 135, and a second source/drain pillar 137, which are disposed in a central region of the hole pattern 107. The first insulating pillar 122 may be formed on the channel layer 113 inside the hole pattern 107.
The second insulating pillar 126 may be disposed between the first source/drain pillar 135 and the second source/drain pillar 137. The first source/drain pillar 135 and the second source/drain pillar 137 may be electrically insulated from each other by the second insulating pillar 126.
The first source/drain pillar 135 and the second source/drain pillar 137 may penetrate the first insulating pillar 122. In an embodiment, the first source/drain pillar 135 and the second source/drain pillar 137 may penetrate portions of the channel layer 113. A current having a predetermined magnitude may flow through the channel layer 113 by applying a voltage between the first source/drain pillar 135 and the second source/drain pillar 137.
Referring to
The dielectric layer 115 may be an interface insulating layer. The dielectric layer 115 may include an insulating material. The dielectric layer 115 may serve as a barrier layer for preventing material diffusion between the channel layer 113 and ferroelectrics as the data storage layer 111. Also, when the data storage layer 111 and the channel layer 113 have difference lattice constants, the dielectric layer 115 may block direct contact between the data storage layer 111 and the channel layer 113. As a result, a crystal defect due to a lattice mismatch may be prevented from occurring at an interface between the data storage layer 111 and the channel layer 113 or the crystal defect may be mitigated. As the density of the crystal defect increases, the reliability of a polarization switching operation of the data storage layer 111 may deteriorate, and the durability of the polarization switching operation may be degraded. The dielectric layer 115 may reduce the occurrence of the crystal defect so that the reliability and durability of the polarization switching operation of the data storage layer 111 may be improved.
Referring to
The dielectric layer 115 may be substantially the same as the dielectric layer 115 of the non-volatile memory device, described with reference to
The metal layer 117 may perform a similar function as the dielectric layer 115. Alternatively, the metal layer 117 may be disposed between the channel layer 113 and the data storage layer 111 to perform a function of reinforcing a polarization state of ferroelectrics as the data storage layer 111.
Referring to
The sacrificial insulating layers 103 may be formed of an insulating material for sacrificial insulating layers, and the interlayer insulating layers 105 may be formed of an insulating material for interlayer insulating layers. The sacrificial insulating layers 103 may be formed of a material that is different from the material of the interlayer insulating layers 105. More specifically, the sacrificial insulating layers 103 may be formed of a material that can be etched while minimizing etching of the interlayer insulating layers 105 in a process of selectively etching the sacrificial insulating layers 103. In other words, the sacrificial insulating layers 103 may be formed of a material having a large etch rate difference from the interlayer insulating layers 105. For example, the sacrificial insulating layers 103 may be formed of a nitride layer, such as a silicon nitride layer (SiN), and the interlayer insulating layers may be formed of an oxide layer, such as a silicon oxide layer (S102).
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A portion of each of the sacrificial insulating layers 103 may be selectively etched, thereby forming a first concave part RE1. The first concave part RE1 may be disposed at the same level as each of the sacrificial insulating layers 103. In an embodiment, a wet etching process may be used for the etching of the sacrificial insulating layers 103. Accordingly, a sidewall surface of the stack structure 101 may have an uneven or winding shape inside the hole pattern 107. The plurality of interlayer insulating layers 105 may have a shape that protrudes farther into the hole pattern 107 compared to the plurality of sacrificial insulating layers 103.
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Subsequently, a conductive material may be filled in regions in which the sacrificial insulating layers 103, shown in
Through the above-described process, a gate structure 110 including the gate electrode layers 203 and the interlayer insulating layers 105 may be formed.
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Hereinafter, a write operation on the second memory cell MC2 will be described with reference to
In addition, a write operation on the third memory cell MC3 will be described with reference to
A read operation on the non-volatile memory device including the first to fourth memory cells MC1, MC2, MC3, and MC4 may be performed as follows. In an example, each of read operations on the second memory cell MC2 and the third memory cell MC3 will be described. First, a predetermined reference voltage may be applied to the first to fourth gate electrode layers 203a, 203b, 203c, and 203d. The reference voltage might not change a polarization state in the first to fourth memory parts 111A, 111B, 111C, and 111D. The reference voltage may be a sufficiently high voltage at which all transistors of the first to fourth memory cells MC1, MC2, MC3, and MC4 can be turned on. Accordingly, a conductive channel may be formed along the Z direction inside the channel layer 113. Subsequently, when a voltage is applied to the first source/drain pillar 135 and the second source/drain pillar 137, a channel current having a constant magnitude can be secured between the first source/drain pillar 135 and the second source/drain pillar 137, regardless of a residual polarization state that is stored in the first to fourth memory parts 111A, 111B, 111C, and 111D.
Subsequently, the magnitude of a gate voltage that is applied to the second gate electrode layer 203b, corresponding to the second memory cell MC2 to be read, may be changed. Specifically, while the magnitude of the gate voltage is decreased to be smaller than the magnitude of the reference voltage, a limit magnitude of a gate voltage capable of securing a current having the same magnitude as the channel current may be read.
Meanwhile, in the same manner, after the channel current flows between the first source/drain pillar 135 and the second source/drain pillar 137, the magnitude of a gate voltage that is applied to the third gate electrode layer 203c, corresponding to the third memory cell MC3 to be read, may be changed. While the magnitude of the gate voltage is decreased to be smaller than the magnitude of the reference voltage, a limit magnitude of a gate voltage may be read. The limit magnitude of the gate voltage may be a magnitude capable of securing a current having the same magnitude as the channel current.
In an example, as shown in
In another example, as shown in
Meanwhile, based on a polarity of charges that are disposed adjacent to the channel layer 113, the limit magnitude of the gate voltage corresponding to the third memory cell MC3 in which the second residual polarization Dig is stored may be smaller than the limit magnitude of the gate voltage corresponding to the second memory cell MC2 in which the first residual polarization Di1 is stored. As described above, a limit magnitude of a gate voltage corresponding to a memory cell to be read is measured, thereby identifying residual polarization information stored in the corresponding memory cell. As a result, signal information stored in the corresponding memory cell can be read.
In accordance with various embodiment of the present disclosure, there may be provided a non-volatile memory device capable of increasing a degree of integration of memory cells and an operation speed and reducing signal interference between adjacent memory cells in a structure in which the memory cells are stacked in a direction perpendicular to a substrate.
Number | Date | Country | Kind |
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10-2022-0090104 | Jul 2022 | KR | national |