Memory dual function device with controlled impurity concentration and operating method of same

Abstract

Disclosed are a dual function device capable of simultaneously performing a selection function and a memory function, and an operating method of same. Before a set operation and a reset operation, metal ions are introduced into a resistance change layer as impurities to have a certain concentration gradient. An upper diffusion control layer for controlling the movement of metal ions has a smaller thickness than a lower diffusion control layer, controls the metal ions to flow into the resistance change layer during the set operation, and induces a deficiency of the metal ions in the resistance change layer during the reset operation.

Description

Memory dual-function device with controlled impurity concentration and operating method thereof

[0001] The present invention relates to a dual-function device in which a selection function and a memory function are implemented in a single device, and more particularly, to a dual-function device capable of implementing a selection function and a memory function in a single device by injecting impurities and controlling the concentration of the impurities, and an operating method thereof.

[0002] For information to be stored in memory or for a read operation to be performed, the corresponding cell must be selected. In other words, a single unit cell is divided into a selection element and a storage element. The selection element is accessed via external bit lines and word lines, and information is read from the memory (storage element) or written to the memory through the accessed selection element.

[0003] In particular, memristor devices, which are resistive memories, require a separate selection element having a transistor structure in addition to MRAM or ReRAM that perform memory operations. When a memory of a specific address is selected through the selection element, data is written to or read from the memory. For example, MRAM performs a write operation by changing the magnetization direction of the free end using phenomena such as spin transfer torque, and ReRAM performs a write operation by changing the resistance state through the formation and disappearance of conductive filaments. In addition, in MRAM, a read operation is performed by utilizing the change in resistance state according to the parallel or antiparallel magnetization of the fixed end and the free end, and in ReRAM, the formation and disappearance state of conductive filaments is used for the read operation. In either case, the resistance state is either a high resistance or a low resistance state.

[0004] Without a selector, data may be written to adjacent cells during write operations, or insufficient voltage may be applied to the cells, resulting in incomplete data recording. Furthermore, data reliability may be compromised during read operations due to the influence of adjacent cells.

[0005] As described above, each cell is equipped with a selection element, so that efficient write and read operations can be performed. However, since the selection element is mostly composed of a transistor, the area occupied by the cell becomes an issue when configuring one cell with the selection element and memory. In addition, the selection element is formed using a transistor manufacturing process using CMOS, and the memory element uses a stacked structure process of a ferromagnetic material, a tunneling insulating film, and a ferromagnetic material in MRAM, and a separate manufacturing process for the resistance change layer in ReRAM. Therefore, the area of ​​the cell where the selection element and memory element are formed increases, and the manufacturing process becomes complicated.

[0006] To solve the above problem, a technology is proposed to reduce the cell size and perform effective access operation through a similar process for the selection element and the memory element.

[0007] U.S. Patent No. 8,947,908 describes a device that arranges two resistive switches in series, forming a vertically stacked structure. The resistive switches are made of chalcogenide materials, and their threshold voltages have different configurations. That is, in a vertically stacked structure, one operates as a selection element performing a switching operation, while the other has a memory function. The patent has the advantage of implementing both a selection element and a memory element in a single stacked structure. However, due to the inherent physical properties of chalcogenide materials, there is a problem of threshold voltage dispersion and reduced operational stability.

[0008] If selection and memory functions are implemented simultaneously in a single device, process stability, cell area reduction, and stable operation will be possible. However, it is a very difficult technology to implement selection and memory functions simultaneously in a single device.

[0009] The first technical task of the present invention is to provide a dual-function device that simultaneously performs a selection function and a memory function.

[0010] In addition, the second technical task to be achieved by the present invention is to provide an operating method of a dual-function device provided by achieving the first technical task.

[0011] In order to achieve the first technical problem described above, the present invention provides a dual-function device including a lower electrode; a lower ion supply layer formed on the lower electrode and supplying Te metal ions; a lower diffusion control layer formed on the lower ion supply layer and controlling movement of the Te metal ions; a resistance change layer formed on the lower diffusion control layer and having a concentration gradient of the Te metal ions; an upper diffusion control layer formed on the resistance change layer and having a thickness smaller than the lower diffusion control layer and controlling movement of the Te metal ions; an upper ion supply layer formed on the upper diffusion control layer and allowing the Te metal ions to flow in and out through the upper diffusion control layer; and an upper electrode formed on the ion supply layer.

[0012] In order to achieve the second technical problem described above, the present invention provides a method for operating a dual-function device, comprising: a lower electrode connected to a bit line, a lower ion supply layer formed on the lower electrode, a lower diffusion control layer formed on the lower ion supply layer, a resistance change layer formed on the lower diffusion control layer, an upper diffusion control layer formed on the resistance change layer and having a thickness smaller than that of the lower diffusion control layer, an upper ion supply layer formed on the upper diffusion control layer, and a word line, the method comprising: applying a set voltage having a positive level between the upper electrode and the lower electrode to a resistance change layer having a distribution in which the concentration of metal ions decreases from an area adjacent to the lower diffusion control layer to an area adjacent to the upper diffusion control layer through doping; and applying a read voltage having a positive level smaller than the set voltage to the resistance change layer in a low-resistance state by applying the set voltage, thereby checking the resistance state of the dual-function device.

[0013] According to the present invention described above, the resistance change layer has a preset concentration gradient. That is, the concentration of metal ions is set to decrease from the bottom to the top. In addition, the thickness of the lower diffusion control layer is set to be greater than the thickness of the upper diffusion control layer, so that the entry into the low resistance state during cell operation is realized by metal ions flowing into the resistance change layer through the upper diffusion control layer. In addition, the entry into the high resistance state during the reset operation is realized by flowing into the upper ion supply layer from the resistance change layer through the upper diffusion control layer. Therefore, a high resistance state is formed due to a deficiency of metal ions in the resistance change layer region adjacent to the upper diffusion control layer.

[0014] This allows selection and read operations to be performed simultaneously, and selection and memory operations to be performed simultaneously without employing a separate selection element. In addition, a concentration gradient of metal ions is formed during the formation of the resistance change layer, and set and reset operations are performed with a single pulse voltage application, thereby ensuring fast operation speeds in set and reset operations.

[0015] FIG. 1 is a cross-sectional view of a dual-function device according to a preferred embodiment of the present invention.

[0016] FIG. 2 is a schematic diagram illustrating the set operation of a dual-function device according to a preferred embodiment of the present invention and a graph showing the concentration distribution of metal ions.

[0017] FIG. 3 is a graph showing the transmission characteristics according to the set operation of FIG. 2 according to a preferred embodiment of the present invention.

[0018] FIG. 4 is a graph showing the change in concentration of metal ions in a resistance change layer when voltage corresponding to each section is applied in the set state of FIG. 3 according to a preferred embodiment of the present invention.

[0019] FIG. 5 is a schematic diagram illustrating the reset operation of a dual-function device according to a preferred embodiment of the present invention and a graph showing the concentration distribution of metal ions.

[0020] FIG. 6 is a graph showing the transmission characteristics according to the reset operation of FIG. 5 according to a preferred embodiment of the present invention.

[0021] FIG. 7 is a graph showing the concentration distribution of metal ions in each section in the transmission characteristics of FIG. 6 according to a preferred embodiment of the present invention.

[0022] FIG. 8 is a circuit diagram illustrating an access operation of a dual-function element for set operation according to a preferred embodiment of the present invention.

[0023] FIG. 9 is a circuit diagram for explaining a read operation according to a preferred embodiment of the present invention.

[0024] Figure 10 is a current-voltage graph measuring the operation of a dual-function device manufactured according to a manufacturing example of the present invention.

[0025] The present invention is susceptible to various modifications and takes various forms. Specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0026] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0027] Hereinafter, with reference to the attached drawings, a preferred embodiment of the present invention will be described in more detail.

[0028]

[0029] Example

[0030] FIG. 1 is a cross-sectional view of a dual-function device according to a preferred embodiment of the present invention.

[0031] Referring to FIG. 1, the dual-function device of the present invention has a lower electrode (110), a lower ion supply layer (120), a lower diffusion control layer (130), a resistance change layer (140), an upper diffusion control layer (150), an upper ion supply layer (160), and an upper electrode (170) on a substrate.

[0032] The substrate is not limited to a semiconductor material, an insulating material, or a metallic material, and there are no special limitations as long as the material does not change its physical properties even when the film materials mentioned in the subsequent process are formed. For example, the substrate may have a SiO2 material. In addition, the substrate may be composed of the same material as the lower electrode (110), so that the substrate itself can perform the function of the lower electrode (110).

[0033] The lower electrode (110) formed on the substrate is formed for application of an electric field and has a conductive material. For example, the lower electrode (110) may have tungsten (W).

[0034] A lower ion supply layer (120) is formed on the lower electrode (110). The lower ion supply layer (120) preferably includes a chalcogen element. For example, the lower ion supply layer (120) has Te. When an electric field is applied to the lower ion supply layer (120), the metal ions of Te can flow into the resistance change layer (140) and can flow from the resistance change layer (140) to the lower ion supply layer (120).

[0035] A lower diffusion control layer (130) is formed on the lower ion supply layer (120). The lower diffusion control layer (130) is made of Ti or TiN and controls the movement of metal ions. That is, the lower diffusion control layer (130) is located in the movement path of metal ions such as Te flowing out or flowing in from the lower ion supply layer (120) and acts as a valve for the movement of metal ions.

[0036] A resistance change layer (140) is formed on the lower diffusion control layer (130). The resistance change layer (140) is composed of an amorphous chalcogenide or metal oxide. The chalcogenide is GeS2, SiS2, GeSe2, or SiSe2, and the metal oxide is AlO. x , ZnO x , TiO x , TaO x or InO x . The metal oxide has a non-stoichiometric composition, and x, which represents the fraction of oxygen, is an example of expressing the non-stoichiometric composition.

[0037] In addition, the resistance change layer (140) is doped with the same element as the lower ion supply layer (120) and the upper ion supply layer (160). For example, the resistance change layer (140) is doped with Te, and Te acts as an impurity and causes defects in the amorphous resistance change layer (140). In addition, the concentration of Te, which is a doped dopant, has a gradual concentration gradient. That is, the concentration of the dopant gradually decreases toward the top. At this time, doping of impurities or defects such as Te is performed through co-sputtering. The gradual dopant concentration gradient can be created by gradually reducing the RF power for the Te target during co-sputtering.

[0038] In particular, when Te is used as a dopant, Te cannot combine with sulfur compounds such as GeS2 due to its large ionic radius, and forms defects. That is, the dopant does not have a chemical bond with the material that acts as the matrix of the resistance change layer (140), and does not combine with oxygen, etc., so it is desirable for it to exist as a defect with an unshared electron pair.

[0039] That is, it is preferable that the resistance change layer (140) is already doped with Te before Te ions are supplied from the ion supply layers (120, 160), and has a profile in which the concentration of Te decreases from the bottom to the top.

[0040] An upper diffusion control layer (150) is formed on the resistance change layer (140). It is preferable that the upper diffusion control layer (150) be formed of the same material as the lower diffusion control layer (130). The upper diffusion control layer (150) acts as a valve for metal ions and controls the operation of allowing metal ions to flow into the upper ion supply layer (160) or flowing out of the upper ion supply layer (160) into the resistance change layer (140).

[0041] In addition, it is preferable that the thickness of the upper diffusion control layer (150) is smaller than the thickness of the lower diffusion control layer (130). Therefore, metal ions can flow into or out of the resistance change layer (140) from the upper ion supply layer (160) through the upper diffusion control layer (150) more easily than through the lower ion supply layer (120).

[0042] An upper ion supply layer (160) is formed on the upper diffusion control layer (150). It is preferable that the upper ion supply layer (160) has the same material as the lower ion supply layer (120). When an electric field or electrical stimulus is applied through the upper electrode (170), the upper ion supply layer (160) supplies metal ions to the resistance change layer (140) through the upper diffusion control layer (150). The upper ion supply layer (160) has a chalcogen element and is preferably composed of Te.

[0043] An upper electrode (170) is formed on the upper ion supply layer (160). An electric field needs to be applied from an external power source through the upper electrode (170), and the upper electrode (170) may be made of tungsten or platinum, but is not limited thereto. Any conductive material can be used as the upper electrode (170).

[0044] FIG. 2 is a schematic diagram illustrating the set operation of a dual-function device according to a preferred embodiment of the present invention and a graph showing the concentration distribution of metal ions.

[0045] Referring to (a) of Fig. 2, a single pulse set voltage V is applied between the upper electrode (170) and the lower electrode (110). set A set operation is performed by applying a set. In the present invention, the set operation refers to an operation in which metal ions flow into the resistance change layer (140) from the upper ion supply layer (160) in a state in which the internal defects have a concentration slanted upward due to metal doping within the resistance change layer (140). In addition, in the set operation, since the lower diffusion control layer has a relatively large thickness, the metal ions passing through the lower diffusion control layer are almost non-existent or minimal.

[0046] When a positive pulse is applied for the set operation, Te metal ions pass through the upper ion supply layer (160) to the upper diffusion control layer (150) having a relatively thin thickness and flow into the resistance change layer (140).

[0047] Referring to (b) of Fig. 2, the resistance switching layer already has a lower impurity concentration of Te as it goes upward, and the impurity concentration is 0 near the interface between the resistance switching layer and the upper diffusion control layer before the set operation. In addition, a region where no metal ions exist may exist with a small size of 3 nm or less. Therefore, the metal ions introduced into the resistance switching layer through the upper ion supply layer by the set operation cause a change in the impurity concentration within the resistance switching layer. For example, the metal ions have a constant concentration in the interface region adjacent to the upper diffusion control layer, and can form a conductive channel of the metal ions.

[0048] When voltage is applied to the upper and lower electrodes in the set state, the resistance switching layer is turned on at the first threshold voltage, thereby implementing a low resistance state. This phenomenon occurs due to doping with chalcogen elements, as the very small gap between the impurities in the resistance switching layer and the upper diffusion control layer leads to the formation of a conductive channel for metal ions. Therefore, by controlling the size of the gap using the co-sputtering method, the size of the first threshold voltage can be controlled.

[0049] The above three operations can be performed by applying a single pulse signal.

[0050] FIG. 3 is a graph showing the transmission characteristics according to the set operation of FIG. 2 according to a preferred embodiment of the present invention.

[0051] Referring to Fig. 3, the resistance change layer has two threshold voltages. The aspect of the threshold voltage is the first threshold voltage V formed by the set operation. th1 Reset voltage -V due to a new concentration distribution of dopant or metal ions within the resistance change layer by a bias having a negative value. reset are distinguished. In addition, the dual-function device has three operating patterns depending on the voltage applied between the upper and lower electrodes.

[0052] In the present invention, voltage is expressed as a positive value. This represents the voltage difference between the upper and lower electrodes, and the reset voltage is -V. reset It corresponds to the voltage difference between the upper and lower electrodes, which is a negative value. Therefore, V reset If expressed as , it corresponds to a positive value.

[0053] FIG. 4 is a graph showing the change in concentration of metal ions in a resistance change layer when voltage corresponding to each section is applied in the set state of FIG. 3 according to a preferred embodiment of the present invention.

[0054] Referring to (a) of Fig. 4, when a voltage corresponding to the first section is applied in the set state, the first threshold voltage V th1 By applying the voltage above, the resistance change layer exhibits a low threshold voltage state.

[0055] When the voltage of the first section is applied, the dual-function device is in a low threshold voltage state and maintains a turned-on state or a low-resistance state. In addition, in the first section, the read voltage V read is the voltage V applied for the set operation. set With a lower value, the read voltage V read is the first threshold voltage V th1 has a larger value. Therefore, the read voltage V read By the authorization of the dual function element, it is turned on and has a low resistance state.

[0056] Referring to (b) of Fig. 4, the voltage of the second section is applied in the set state, and the concentration distribution of metal ions or impurities is shown. The second section is the first threshold voltage V th1 Less than, reset voltage -V reset It has a value exceeding . Even if the concentration distribution of impurities is formed within the resistance change layer adjacent to the lower diffusion control layer in the above section, the resistance change layer cannot implement a turn-on or low-resistance state, but maintains a high-resistance state or an off state.

[0057] In particular, a high resistance state appears in a region where the voltage difference between the upper electrode and the lower electrode maintains a (-) value. This is because the metal ions distributed at the interface of the upper diffusion control layer move to the upper ion supply layer, and the distribution of metal ions is hardly observed in the interface region adjacent to the upper diffusion control layer.

[0058] In addition, since the movement of metal ions within the amorphous resistance-changing layer is not easy, even if a negative voltage difference is applied, the concentration distribution of metal ions or impurities does not change significantly. In addition, since the lower diffusion-control layer has a relatively large thickness, metal ions flowing from the lower ion supply layer to the resistance-changing layer hardly appear, so a deficiency of metal ions occurs at the interface with the upper diffusion-control layer, resulting in a high-resistance state.

[0059] Referring to (c) of Fig. 4, in the third section, the voltage difference between the upper electrode and the lower electrode is the reset voltage -V reset is set below. That is, the magnitude of the voltage difference is the reset voltage V reset is set to a value greater than or equal to the reset voltage -V reset When the voltage below is applied to the resistance change layer, movement of impurities or dopants may occur within the resistance change layer. That is, metal ions move within the amorphous phase, increasing the concentration of impurities in the region adjacent to the upper diffusion control layer, and metal ions are introduced from the lower ion supply layer in the region adjacent to the lower diffusion control layer.

[0060] That is, the concentration of impurities is formed with a high gradient within the resistance change layer, and the reset voltage V reset Below, it is turned on again to implement a high threshold voltage state.

[0061] The above-described behavior is due to the phenomenon that metal ions do not form chemical bonds with metal oxides, etc., which constitute the matrix of the resistance-changing layer. That is, the dopant and the metal oxide, etc. are formed through co-sputtering. The above process is a process in which a metal oxide target and a metal target, which is a dopant, are simultaneously placed, and the metal oxide and the dopant are simultaneously formed through irradiation with an ion beam or electron beam. The dopant does not form a chemical bond with the metal oxide and acts as a pure impurity. Therefore, the ionized dopant can move within the metal oxide by a strong electric field.

[0062] FIG. 5 is a schematic diagram illustrating the reset operation of a dual-function device according to a preferred embodiment of the present invention and a graph showing the concentration distribution of metal ions.

[0063] Referring to (a) of Fig. 5, a reset voltage -V, which is a negative voltage, is applied as a single pulse between the upper electrode (170) and the lower electrode (110). reset This is authorized. In the manufacturing process prior to the reset operation, a concentration gradient of impurities is formed within the resistance change layer (140) by doping with metal ions, and a lower concentration of impurities appears toward the top.

[0064] When a negative pulse is applied through a reset operation, a large negative voltage difference is generated between the upper electrode (170) and the lower electrode (110). The reset voltage -V reset is the reading voltage V read It has a larger size and has a size that can induce the movement of metal ions through the upper diffusion control layer (150). The applied reset voltage is -V reset Although metal ions can penetrate the lower diffusion control layer (130), the amount is much smaller than the amount of metal ions that can move through the upper diffusion control layer.

[0065] Referring to (b) of Fig. 5, the reset voltage -V reset Due to the strong negative electric field caused by the upper diffusion control layer, metal ions adjacent to the upper diffusion control layer move through the upper diffusion control layer to the upper ion supply layer. Therefore, a low concentration or deficiency of impurities due to metal ions occurs in the region adjacent to the upper diffusion control layer.

[0066] However, the amount of metal ions flowing into the resistance change layer through the lower diffusion control layer from the lower electrode due to the reset operation is very small compared to the amount passing through the upper diffusion control layer. Therefore, the concentration distribution of metal ions at the interface of the lower diffusion control layer before the reset operation and the concentration distribution of metal ions after the reset operation do not change significantly.

[0067] That is, through the reset operation, metal ions within the resistance switching layer flow toward the upper electrode. Due to the low impurity concentration, the resistance switching layer maintains a high resistance state, and the device transitions to a high threshold voltage state.

[0068] FIG. 6 is a graph showing the transmission characteristics according to the reset operation of FIG. 5 according to a preferred embodiment of the present invention.

[0069] Referring to Figure 6, the transmission characteristics are divided into three sections.

[0070] The first section involves applying a negative voltage in the reset state, whereby metal ions flow from the lower ion supply layer into the resistance-changing layer due to a very high negative electric field, and metal ions also move within the resistance-changing layer due to the electric field. Therefore, the resistance-changing layer can enter a low-resistance state.

[0071] Also, the second section is -V in reset state reset Ideal or second threshold voltage V th2 By applying a voltage less than 10 V, the inflow of metal ions from the upper ion supply layer by a positive voltage is minimal due to the low voltage difference. Therefore, in the second section, the dual-function device remains in the off state. The second threshold voltage V th2 refers to the voltage at which the resistance change layer is turned on by the voltage applied in the reset state. The second threshold voltage V is set by the reset operation. th2 is the first threshold voltage V th1 It has a larger value.

[0072] The third section is the second threshold voltage V in the reset state. th2 When the voltage above is applied, this is an operation that implements a low resistance state together with a set operation in the reset state.

[0073] FIG. 7 is a graph showing the concentration distribution of metal ions in each section in the transmission characteristics of FIG. 6 according to a preferred embodiment of the present invention.

[0074] First, referring to (a) of Fig. 7, a voltage of the first section is applied in the reset state. When a very large negative voltage is applied, metal ions flow from the lower ion supply layer through the lower diffusion control layer into the resistance change layer, and movement of metal ions also occurs within the resistance change layer. In addition, the metal ions within the resistance change layer move to the upper ion supply layer. However, the metal ion deficiency phenomenon does not occur due to the movement of metal ions within the resistance change layer, and a low-resistance state appears.

[0075] Furthermore, since the movement of metal ions within the resistance-changing layer presupposes movement within the amorphous matrix, smooth movement is not observed even when a voltage difference is applied. However, due to the thin thickness of the upper diffusion control layer, metal ions migrate from the upper ion supply layer to a limited area. Therefore, metal ions are distributed in the interface region of the upper diffusion control layer.

[0076] Therefore, the metal ions are sufficiently distributed within the resistance change layer and turned on in a low resistance state.

[0077] Referring to Fig. 7 (b), a voltage of the second section is applied in the reset state. In the voltage range of the second section, a change in the concentration distribution of metal ions within the resistance change layer occurs minimally or hardly at all. For example, even if a positive voltage is applied between the upper electrode and the lower electrode, the amount of metal ions supplied from the upper ion supply layer to the resistance change layer is very minimal. In addition, when a negative voltage is applied between the upper electrode and the lower electrode, some positive metal ions within the resistance change layer may penetrate the upper diffusion control layer and flow into the upper ion supply layer. Therefore, the deficiency of metal ions in the resistance change layer adjacent to the upper diffusion control layer is aggravated, and a high resistance state is maintained.

[0078] Referring to (c) of Fig. 7, a case is initiated in which a voltage corresponding to the third section is applied in the reset state. The second threshold voltage V th2 When the voltage above is applied, metal ions flow from the upper ion supply layer to the resistance change layer through the upper diffusion control layer. Therefore, the resistance change layer becomes low-resistance. However, the amount of metal ions flowing from the resistance change layer to the lower ion supply layer through the lower diffusion control layer is minimal or almost nonexistent.

[0079] FIG. 8 is a circuit diagram illustrating an access operation of a dual-function element for set operation according to a preferred embodiment of the present invention.

[0080] Referring to FIG. 8, a plurality of word lines (211, 212, 213) and bit lines (311, 312, 313) are provided in a form in which they cross each other vertically. Dual-function elements (100) of FIG. 1 are respectively arranged in the vertically crossing areas.

[0081] The upper electrode of the dual-function device (100) is connected to the word lines (211, 212, 213), and the lower electrode is connected to the bit lines (311, 312, 313). In addition, since all dual-function devices (100) will be in the set state due to the preset concentration gradient after the device is manufactured, it is assumed that they are in the set state during the initial operation. Next, a reset operation is performed on a cell of the dual-function device connected to a specific word line and bit line. For example, a reset operation is performed on a cell connected to a second word line (212) and a second bit line (312).

[0082] The reset operation of the selected cell consisting of a dual function element is performed by applying voltage V to the second word line (212). reset or higher level, and a selection signal V is applied to the second bit line (312). sel (=0V) is applied. The voltage difference between the upper and lower electrodes is -V reset Below, the corresponding cell enters the reset state. For example, 0 V is applied to the unselected word lines (211, 213), and for example, a non-select signal V is applied to the unselected bit lines (311, 313). unsel (=V read ) is applied. The voltage difference applied to the unselected cells is a negative voltage difference, -V reset Since the level of the non-selected signal V is exceeded, the reset operation is not performed. In addition, a reset state is formed in the selected cell, and since it is in a high resistance state, no leakage current occurs from the non-selected cell. In addition, the level of the non-selected signal V read is disclosed in the above drawings 3 and 6, and the first threshold voltage V th1 and the second threshold voltage V th2 It has a value between .

[0083] Reset voltage -V, which is the voltage difference between the selection action and the selected cell reset The reset operation is performed by authorization.

[0084] If it is assumed that the cell connected to the second word line (212) and the second bit line (312) is in a reset state and a set operation is performed on the selected cell, the set operation of the cell composed of a dual-function element is performed by applying a set voltage V to the second word line (212). set , and select signal V is applied to the second bit line (312). sel (=0V) is applied. The voltage difference between the upper and lower electrodes is V set Therefore, the corresponding cell enters the set state. Voltage is applied to the unselected word lines and bit lines in the same manner as the reset operation.

[0085] FIG. 9 is a circuit diagram for explaining a read operation according to a preferred embodiment of the present invention.

[0086] Referring to Fig. 9, the reset operation is performed only on the cells connected to the second word line (212) and the second bit line (312) in Fig. 8. To select the corresponding cell, a read voltage V is applied to the second word line (212). read is applied, and the second bit line (312) is provided with a selection signal V sel (=0V) is applied. The remaining unselected cells are subjected to a voltage difference of 0V or -V read A voltage difference of V is applied. Therefore, the unselected cell is in a low threshold voltage state and is interpreted as an on state. The selected cell is in a voltage difference V read is turned off by and is read as a high threshold voltage state.

[0087] Let us assume that a read operation is performed on a cell connected to the first word line (211) and the second bit line (312) in a low threshold voltage state. A read voltage V is applied to the first word line (211). read is applied, and a selection signal V is applied to the second bit line (312). sel (=0V) is applied, the voltage difference between the upper and lower electrodes of the cell is V readAs can be seen in the above figure 3, the cell is in a set state and has a low threshold voltage state, so the data in the on state is read. In addition, the remaining unselected cells have a voltage difference of 0 V or -V read is authorized and only high resistance states appear.

[0088] In the above operation, the selection signal V sel Although this is assumed to be 0V, the above selection signal can be changed in various ways. Also, the non-selection signal V unsel Silver read signal V read Assumed to be V, the above non-selected signal is read With a larger value, it is acceptable to form the voltage difference between the upper and lower electrodes of the unselected cells as a negative value.

[0089] Additionally, after the read operation of the above-described FIG. 9 is performed, a reset operation for the corresponding cell may be performed, so that an initialization operation of the cell may be performed.

[0090]

[0091] Manufacturing example

[0092] Tungsten (W) is formed as a lower electrode on a silica substrate, and a Te material is used as a lower ion supply layer on the lower electrode, with a thickness of 3 nm. In addition, TiN is used as a lower diffusion control layer on the lower ion supply layer, with a thickness set to 3 nm.

[0093] Next, a resistance change layer made of GeS2 material is formed with a thickness of 60 nm, and a resistance change layer doped with Te as an impurity is formed through co-sputtering of GeS2 and Te. During co-sputtering, the operating pressure in the chamber is 8 mTorr, the gun power applied to GeS2 is 30 W, and the gun power applied to the Te target is gradually adjusted from 10 W to 5 W. Through this, a resistance change layer is formed in which the concentration of Te decreases from the lower diffusion control layer to the upper part.

[0094] Next, an upper diffusion control layer made of TiN material is formed with a thickness of 1 nm on the resistance change layer, an upper ion supply layer made of Te material is formed with a thickness of 3 nm on the upper diffusion control layer, and an upper electrode made of platinum material is formed with a thickness of 50 nm.

[0095] Figure 10 is a current-voltage graph measuring the operation of a dual-function device manufactured according to a manufacturing example of the present invention.

[0096] Referring to Fig. 10, it is confirmed that the device is in a low threshold voltage state due to a preset concentration gradient during initial operation and turns on at a first threshold voltage of 0.65 V.

[0097] Additionally, after a reset operation occurs when a reset voltage of -3 V is applied, the device switches to a high threshold voltage state due to a deficiency of metal ions in the resistance change layer of the dual-function device. Since it is in a high threshold voltage state when voltage is applied thereafter, it turns on above the second threshold voltage of 2.5 V.

[0098]

[0099] In the present invention described above, the resistance change layer has a preset concentration gradient. That is, the concentration of metal ions is set to decrease from the bottom to the top. In addition, the thickness of the lower diffusion control layer is set to be greater than the thickness of the upper diffusion control layer, so that the entry into the low resistance state during cell operation is realized by metal ions flowing into the resistance change layer through the upper diffusion control layer. In addition, the entry into the high resistance state during the reset operation is realized by flowing into the upper ion supply layer from the resistance change layer through the upper diffusion control layer. Therefore, a high resistance state is formed due to a deficiency of metal ions in the resistance change layer region adjacent to the upper diffusion control layer.

[0100] This allows selection and read operations to be performed simultaneously, and selection and memory operations to be performed simultaneously without employing a separate selection element. In addition, a concentration gradient of metal ions is formed during the formation of the resistance change layer, and set and reset operations are performed with a single pulse voltage application, thereby ensuring fast operation speeds in set and reset operations.

Claims

1. Lower electrode; A lower ion supply layer formed on the lower electrode and for supplying Te metal ions; A lower diffusion control layer formed on the lower ion supply layer and for controlling the movement of the Te metal ions; A resistance change layer formed on the lower diffusion control layer and having a concentration gradient of the Te metal ions; An upper diffusion control layer formed on the resistance change layer, having a thickness smaller than that of the lower diffusion control layer, and for controlling the movement of the Te metal ions; An upper ion supply layer formed on the upper diffusion control layer and through which Te metal ions flow in and out through the upper diffusion control layer; and A dual-function device comprising an upper electrode formed on the ion supply layer.

2. In the first paragraph, the resistance change layer is a dual-function device characterized in that the concentration of the Te metal ion decreases from the lower diffusion control layer to the upper diffusion control layer.

3. In the second paragraph, when a set voltage having a positive level is applied between the upper electrode and the lower electrode, the Te metal ions of the upper ion supply layer penetrate the upper diffusion control layer and are distributed to the resistance change layer adjacent to the upper diffusion control layer, thereby implementing a low threshold voltage state. A dual-function device.

4. A dual-function device characterized in that a read voltage of a level lower than the set voltage is applied between the upper electrode and the lower electrode in the third paragraph.

5. In the second paragraph, when a reset voltage having a negative level is applied between the upper electrode and the lower electrode, the Te metal ions of the resistance change layer penetrate the upper diffusion control layer, and a deficiency of the Te metal ions occurs in the resistance change layer adjacent to the diffusion control layer, thereby implementing a high threshold voltage state. A dual-function device.

6. A dual-function device according to claim 1, wherein the resistance change layer is an amorphous chalcogenide or an amorphous metal oxide.

7. A dual-function device according to claim 6, wherein the resistance change layer comprises GeS2, SiS2, GeTe2 or SiTe2.

8. A dual-function device according to claim 1, wherein the upper diffusion control layer and the lower diffusion control layer comprise Ti or TiN.

9. In a method for operating a dual-function device, comprising: a lower electrode connected to a bit line, a lower ion supply layer formed on the lower electrode, a lower diffusion control layer formed on the lower ion supply layer, a resistance change layer formed on the lower diffusion control layer, an upper diffusion control layer formed on the resistance change layer and having a thickness smaller than that of the lower diffusion control layer, an upper ion supply layer formed on the upper diffusion control layer, and an upper ion supply layer formed on the upper ion supply layer and connected to a word line; A step of applying a set voltage having a positive level between the upper electrode and the lower electrode to a resistance change layer having a distribution in which the concentration of metal ions decreases from an area adjacent to the lower diffusion control layer to an area adjacent to the upper diffusion control layer through doping; and An operating method of a dual-function device for checking the threshold voltage state of the dual-function device by applying a read voltage having a level smaller than the set voltage to a resistance change layer in a low threshold voltage state by applying the set voltage.

10. A method of operating a dual-function device, characterized in that, in the 9th paragraph, by applying the set voltage, the metal ions penetrate the upper diffusion control layer and flow into the resistance change layer from the upper ion supply layer.

11. In the 10th paragraph, the metal ion is Te 2+ A method of operating a dual-function device characterized by:

12. A method of operating a dual-function device according to claim 11, wherein the upper diffusion control layer and the lower diffusion control layer comprise Ti or TiN.

13. A method of operating a dual-function device, characterized in that the resistance change layer in paragraph 9 is an amorphous chalcogenide or an amorphous metal oxide.

14. A method of operating a dual-function device, characterized in that the amorphous chalcogenide of the resistance change layer and the metal ion in the 13th paragraph are formed through co-sputtering.

15. In the 9th paragraph, a method for operating a dual-function device characterized in that, after applying the read operation, a reset voltage having a negative level is applied between the upper electrode and the lower electrode to induce a deficiency of the metal ions in the region of the resistance change layer adjacent to the upper diffusion control layer, thereby inducing a high threshold voltage state.

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