One-time programmable read-only memory and writing method and reading method thereof

Abstract

The present invention provides a one-time programmable read-only memory and a writing method and a reading method thereof, which relate to the technical field of integrated circuits, and include a storage unit, wherein the storage unit includes: a first electrode layer, a second electrode layer, and a single material layer between the first electrode layer and the second electrode layer; the storage unit has a first threshold transition voltage and a second threshold transition voltage, and the first threshold transition voltage is greater than the second threshold transition voltage; the storage unit also has a first writing voltage and a reading voltage, and the first writing voltage is greater than the first threshold transition voltage; the first reading voltage is greater than the second threshold transition voltage, and the first reading voltage is less than the first threshold transition voltage. The present invention not only has the function of threshold switching, but also has the advantages of storage function, low static power consumption, simple structure, low process requirements, three-dimensional integration and three-dimensional miniaturization, and is suitable for a cross array structure, especially a high-density three-dimensional one-time programmable read-only memory.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a one-time programmable read-only memory based on a new material and a new device structure, and a writing method and a reading method thereof. Background Art

[0002] With the rapid development of information technology, people have higher requirements for the cost, security and reliability of memory. Compared with traditional non-volatile memory, One Time Programming ROM (OTP-ROM) is only allowed to be written once. When leaving the factory, the stored content is all 0 or 1. Users can write data 1 or 0 to some of the storage cells as needed to achieve the purpose of "programming" it, but this programming write operation is destructive, and each storage cell can only be written once. With its small unit area, high reliability, strong stability and radiation resistance, OTP-ROM is widely used in important occasions such as high stability, high confidentiality and one-time programming, such as radio frequency identification (RFID), chip key information storage, aerospace and other fields.

[0003] The existing typical one-time programmable read-only memory products use a "bipolar fuse structure". If the user wants to rewrite certain storage cells, they can pass a sufficiently large current through these storage cells and maintain it for a certain period of time, and the original fuse will be blown, thus achieving the effect of rewriting certain bits. Another type of classic one-time programmable read-only memory uses a "Schottky diode" as a storage unit. When leaving the factory, the diode is in a reverse cutoff state. The user can use a large current method to add a reverse voltage to both ends of the "Schottky diode" to cause it to permanently break down to achieve programming and write operations. In short, a one-time programmable read-only memory requires additional fuse materials or a breakdown "Schottky diode" structure, requires additional process support, has limited performance, and cannot be integrated at a high density.

[0004] The three-dimensional one-time programmable read-only memory (3D-OTP) is a mass-produced three-dimensional cross-array memory produced by Matrix Semiconductor Corporation in the United States. The storage cell of the three-dimensional one-time programmable read-only memory adopts pure silicon technology, including antifuse and P / i / N silicon diode. The antifuse is used as a storage film and the P / i / N silicon diode is used as a gate film. Since the programmed diode needs to withstand the write voltage VP during programming, the unprogrammed diode needs to withstand -VP / 2. In order to avoid all unprogrammed diodes collectively generating a large leakage current during programming, the diode needs to have a large reverse breakdown voltage, so the thickness HS is large, about 300nm. As the size F of the memory cell shrinks, the aspect ratio of the diode (HS:F) will increase. For example, when it shrinks to the 20nm node, the aspect ratio reaches 15:1, which is more challenging to achieve in terms of process. In addition, since the material of the diode is polysilicon, the conduction performance is limited, and the current density JON under the read voltage can only reach 800A / cm 2 Matrix's 3D one-time programmable read-only memory is slow and has a large read delay.

[0005] Therefore, in view of the above problems, it is urgent to design a new one-time programmable read-only memory and a writing method and a reading method thereof to solve the above problems in the prior art and meet the needs of practical use. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a one-time programmable read-only memory based on a single material and an electrode material, and a writing method and a reading method thereof, which solve the problems of large area, slow speed, and difficulty in integration in the prior art. The one-time programmable read-only memory of the present invention has a simple structure, low process requirements, and can be three-dimensionally integrated and three-dimensionally miniaturized.

[0007] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0008] A one-time programmable read-only memory comprises a storage unit, wherein the storage unit comprises:

[0009] A first electrode layer, a second electrode layer, and a single material layer between the first electrode layer and the second electrode layer;

[0010] The formed memory cell exhibits high resistance in the absence of an external electric field, and the memory cell has:

[0011] a first threshold transition voltage, the first threshold transition voltage being a flip voltage when the memory cell is converted from a high resistance to a low resistance when a voltage is first applied;

[0012] a second threshold transition voltage, the second threshold transition voltage being a flip voltage when the memory cell is converted from a high resistance to a low resistance when a voltage is subsequently applied;

[0013] wherein the first threshold transition voltage is greater than the second threshold transition voltage;

[0014] The storage unit also has:

[0015] a first write voltage, wherein the first write voltage is greater than the first threshold transition voltage;

[0016] a first readout voltage, the first readout voltage being greater than the second threshold transition voltage, and the first readout voltage being less than the first threshold transition voltage.

[0017] In the above-mentioned one-time programmable read-only memory, the storage unit is a cross structure, and the cross storage unit includes:

[0018] More than one storage unit, one of the first electrode layer or the second electrode layer of each storage unit is connected to a first metal layer, and the first metal layer is connected to a first address line;

[0019] A second metal layer, wherein the second metal layer is connected to the other of the first electrode layer or the second electrode layer of all the memory cells, and the second metal layer is connected to a second address line.

[0020] In the above-mentioned one-time programmable read-only memory, the cross memory cells are stacked into N layers in the vertical direction to form a storage density of 4F. 2 / N three-dimensional one-time programmable read-only memory;

[0021] Wherein, F is the characteristic dimension of the semiconductor process, and N is a natural number greater than or equal to 2.

[0022] In the above-mentioned one-time programmable read-only memory, the single material layer forms a single crystal thin film on the first electrode layer and the second electrode layer; and / or the single material layer forms a single crystal thin film on an amorphous substrate;

[0023] At the same time, the single material layer forms a Schottky junction with the first electrode layer and the second electrode layer respectively.

[0024] In the above-mentioned one-time programmable read-only memory, the memory cell exhibits high resistance after being formed, and after a predetermined voltage signal is applied to both ends of the memory cell, the memory cell is instantly changed from a high resistance state to a low resistance state; and

[0025] When the predetermined voltage signal is removed, the storage unit is instantly converted back to a high-impedance state, exhibiting a threshold switching characteristic.

[0026] In the above-mentioned one-time programmable read-only memory, the storage unit further includes:

[0027] a second write voltage for maintaining the memory cell open after the first write voltage is applied to open the memory cell, the second write voltage being less than the first threshold transition voltage and greater than a first maintain threshold transition voltage, the first maintain threshold transition voltage being a voltage that maintains the memory cell from high resistance to low resistance when the voltage is first applied;

[0028] a second read voltage for maintaining the memory cell open after the first read voltage is applied to open the memory cell, the second read voltage being less than the second threshold transition voltage, and the second read voltage being greater than a second sustaining threshold transition voltage, the second sustaining threshold transition voltage being a voltage that maintains the memory cell from a high resistance to a low resistance when a voltage is subsequently applied;

[0029] The initial data stored in the storage unit after being formed is the first predetermined data, the first write voltage is applied first, and then the second write voltage is applied to complete the operation of writing the second predetermined data;

[0030] The memory cell first applies the first read voltage and then applies the second read voltage before performing a write operation to complete an operation of reading the first predetermined data; and

[0031] After the writing operation is performed on the memory cell, the first read voltage is first applied, and then the second read voltage is applied to complete the operation of reading the second predetermined data.

[0032] In the above-mentioned one-time programmable read-only memory, the one-time programmable read-only memory applies a voltage across the two ends of the memory cell and detects the current flowing through the memory cell, thereby completing the read operation of the memory cell according to the magnitude of the current;

[0033] When the memory cell has not been subjected to a write operation, the current flowing through the memory cell is small, and the first predetermined data is output after a read operation is performed; and

[0034] After the memory cell is written into, the current flowing through the memory cell is relatively large, and the second predetermined data is output after the read operation is performed.

[0035] In the above-mentioned one-time programmable read-only memory, when the first predetermined data is "1", the second predetermined data is "0"; and

[0036] When the first predetermined data is "0", the second predetermined data is "1".

[0037] In the above-mentioned one-time programmable read-only memory, the single-element material layer is made of tellurium or selenium.

[0038] In the above-mentioned one-time programmable read-only memory, both the first electrode layer and the second electrode layer are made of titanium nitride or tantalum nitride.

[0039] In the above-mentioned one-time programmable read-only memory, the shape of the storage unit formed by the first electrode layer, the single-element material layer and the second electrode layer is one or more combinations of T-type, μ-type and O-type.

[0040] In the above-mentioned one-time programmable read-only memory, an isolation dielectric layer is provided between each of the storage units.

[0041] The present invention also provides a method for writing a one-time programmable read-only memory, which is used to implement the one-time programmable read-only memory as described above, comprising:

[0042] When performing a write operation, a first write voltage is first applied to both ends of the memory cell to open the memory cell; then a second write voltage is applied to keep the memory cell open and complete the write operation;

[0043] The first write voltage, the first threshold transition voltage, the second write voltage and the first hold threshold transition voltage have the following relationship: Vprog1>Vform>Vprog2>Vholdform;

[0044] Wherein, Vprog1 is the first write voltage;

[0045] Vform is the first threshold transition voltage;

[0046] Vprog2 is the second write voltage;

[0047] Vholdform is the first holding threshold transition voltage.

[0048] The present invention also provides a one-time programmable read-only memory reading method, which is used to implement the one-time programmable read-only memory as described above, comprising:

[0049] When performing a read operation, a first read voltage is first applied to both ends of the memory cell to open the memory cell; a second read voltage is then applied to keep the memory cell open, amplify the current flowing through the memory cell, and complete the read operation;

[0050] The first read voltage, the second threshold transition voltage, the second read voltage and the second hold threshold transition voltage have the following relationship: Vread1>Vth>Vread2>Vhold;

[0051] Wherein, Vread1 is the first read voltage;

[0052] Vth is the second threshold transition voltage;

[0053] Vread2 is the second read voltage;

[0054] Vhold is the second hold threshold transition voltage.

[0055] The beneficial effects of the technical solution of the present invention are:

[0056] The one-time programmable read-only memory of the present invention not only has a threshold switch function, but also has the advantages of a storage function, low static power consumption, simple structure, low process requirements, three-dimensional integration and three-dimensional miniaturization, and is suitable for a cross array structure, especially a high-density three-dimensional one-time programmable read-only memory. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A schematic diagram of the structure of a storage unit of a one-time programmable read-only memory in a preferred embodiment of the present invention;

[0058] Figure 2 This is a schematic diagram of electrical performance under different electrode sizes in a preferred embodiment of the present invention;

[0059] Figure 3 A schematic diagram of the structure of a cross storage unit of a one-time programmable read-only memory in a preferred embodiment of the present invention;

[0060] Figure 4 Schematic diagram of the array structure of the first address line and the second address line of the cross memory unit in a preferred embodiment of the present invention;

[0061] Figure 5 The figure is a schematic structural diagram of a multi-layer cross memory unit of a one-time programmable read-only memory in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0062] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0064] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0065] Embodiment 1

[0066] The embodiment of the present invention provides a one-time programmable read-only memory, which belongs to the technical field of integrated circuits, including a storage unit 01, such as Figure 1 As shown, the storage unit 01 includes:

[0067] A first electrode layer 1, a second electrode layer 2, and a single material layer 3 between the first electrode layer 1 and the second electrode layer 2;

[0068] The formed memory cell 01 exhibits high resistance when there is no external electric field. The memory cell 01 has:

[0069] A first threshold transition voltage Vform, the first threshold transition voltage Vform being a flip voltage when the memory cell 01 changes from a high resistance to a low resistance when a voltage is first applied;

[0070] a second threshold transition voltage Vth, where the second threshold transition voltage Vth is a flip voltage when the memory cell 01 is converted from a high resistance to a low resistance when a voltage is subsequently applied, and the flip voltage here can also be referred to as a turn-on voltage of the memory cell;

[0071] Wherein, the first threshold transition voltage Vform is greater than the second threshold transition voltage Vth;

[0072] Storage unit 01 also has:

[0073] a first write voltage Vprog1, the first write voltage Vprog1 being greater than the first threshold transition voltage Vform;

[0074] A first readout voltage Vread1 is provided. The first readout voltage Vread1 is greater than the second threshold transition voltage Vth, and the first readout voltage Vread1 is less than the first threshold transition voltage Vform.

[0075] Specifically, in this embodiment, the present invention utilizes a single material layer 3 and a first electrode layer 1 and a second electrode layer 2 respectively formed on both sides of the single material layer 3 to form a storage cell 01 of a one-time programmable read-only memory device, and the storage cell 01 includes a first threshold transition voltage Vform and a second threshold transition voltage Vth, as well as a first write voltage Vprog1 and a first read voltage Vread1.

[0076] After the storage cell 01 is formed, it exhibits high resistance in the absence of an external electric field; when voltage is applied for the first time, the flipping voltage when the resistance of the storage cell 01 is converted from high resistance to low resistance is the first threshold transition voltage Vform; when voltage is applied subsequently, the flipping voltage when the resistance of the storage cell 01 is converted from high resistance to low resistance is the second threshold transition voltage Vth; the first threshold transition voltage Vform is greater than the second threshold transition voltage Vth; the first write voltage Vprog1 of the storage cell 01 is greater than the first threshold transition voltage Vform; the first read voltage Vread1 of the storage cell 01 is greater than the second threshold transition voltage Vth, but less than the first threshold transition voltage Vform, that is, Vprog1>Vform>Vread1>Vth.

[0077] By using the above voltage characteristics, the storage unit 01 of the one-time programmable read-only memory device can be read and written. The write operation of the storage unit 01 of the one-time programmable read-only memory can be realized by operating the first threshold transition voltage Vform; the read operation of the storage unit 01 is realized by applying a resistance value greater than the second threshold transition voltage Vth and less than the first threshold transition voltage Vform. The embodiment of the present invention has a threshold switch function and a storage function, and has low static power consumption, simple structure, and low process requirements.

[0078] As a preferred embodiment, the single material layer 3 forms a single crystal film on the first electrode layer 1 and the second electrode layer 2; and / or the single material layer 3 forms a single crystal film on an amorphous substrate;

[0079] At the same time, the single material layer 3 forms a Schottky junction with the first electrode layer 1 and the second electrode layer 2 respectively.

[0080] Specifically, in the present embodiment, the single material layer 3, the first electrode layer 1 and the second electrode layer 2 are all polycrystalline, and a single crystal thin film is formed between the single material layer 3 and the first electrode layer 1, and between the single material layer 3 and the second electrode layer 2, respectively, and a perfect interface is formed between the polycrystalline first electrode layer 1 and the second electrode layer 2; at the same time, a Schottky junction is formed between the single material layer 3 and the first electrode layer 1, and another Schottky junction is formed between the single material layer 3 and the second electrode layer 2.

[0081] Furthermore, since a perfect interface is formed between the single crystal film of the device and the polycrystalline first and second electrode layers 2 and / or the SiN amorphous substrate, no diffusion occurs at a high temperature of 400°C for 30 minutes, which effectively ensures the consistency and stability of the storage device. At the same time, the formed Schottky junction exhibits high resistance, providing extremely low static power consumption for the one-time programmable read-only memory.

[0082] As a preferred embodiment, the memory cell 01 exhibits a high resistance after being formed, and after a predetermined voltage signal is applied to both ends of the memory cell 01, the memory cell 01 is instantly changed from a high resistance state to a low resistance state; and

[0083] When the predetermined voltage signal is removed, the storage unit 01 is instantly converted back to a high-impedance state, showing a threshold switching characteristic.

[0084] Specifically, in this embodiment, a Schottky junction is formed by using a single crystal thin film and a polycrystalline first and second electrode layer 2, which exhibits high resistance in the absence of an external electric field. After a certain predetermined voltage signal is applied to both ends, the resistance value of the storage unit 01 decreases sharply, and it instantly changes from a high resistance state to a low resistance state. When the voltage is removed, it instantly returns to a high resistance state, exhibiting a threshold switching characteristic.

[0085] As a preferred embodiment, the storage unit 01 further includes:

[0086] a second write voltage Vprog2, used to maintain the memory cell 01 open after the first write voltage Vprog1 is applied to open the memory cell 01, the second write voltage Vprog2 is less than the first threshold transition voltage Vform, and the second write voltage Vprog2 is greater than the first hold threshold transition voltage Vholdform, the first hold threshold transition voltage Vholdform is a voltage that maintains the memory cell 01 from high resistance to low resistance when the voltage is first applied;

[0087] a second read voltage Vread2, used to maintain the memory cell 01 opened after the first read voltage Vread1 is applied to open the memory cell 01, the second read voltage Vread2 is less than the second threshold transition voltage Vth, and the second read voltage Vread2 is greater than the second hold threshold transition voltage Vhold, the second hold threshold transition voltage Vhold is a voltage that maintains the memory cell 01 from high resistance to low resistance when a voltage is subsequently applied;

[0088] After the storage unit 01 is formed, the initial data stored is the first predetermined data. The first write voltage Vprog1 is applied first, and then the second write voltage Vprog2 is applied to complete the operation of writing the second predetermined data.

[0089] Before performing a write operation, the memory cell 01 first applies a first read voltage Vread1 and then applies a second read voltage Vread2 to complete an operation of reading out the first predetermined data; and

[0090] After the write operation is performed, the memory cell 01 first applies the first read voltage Vread1 and then applies the second read voltage Vread2 to complete the operation of reading the second predetermined data.

[0091] Specifically, the memory cell 01 further includes a first maintaining threshold transition voltage Vholdform and a second maintaining threshold transition voltage Vhold, as well as a second write voltage Vprog2 and a second read voltage Vread2. In this embodiment, the memory cell 01 is turned on by first applying a voltage once, and then the applied voltage is reduced to maintain the memory cell 01 turned on. Therefore, the first threshold transition voltage Vform corresponds to the first maintaining threshold transition voltage Vholdform, the second threshold transition voltage Vth corresponds to the second maintaining threshold transition voltage Vhold, the first write voltage Vprog1 corresponds to the second write voltage Vprog2, and the first read voltage Vread1 corresponds to the second read voltage Vread2. By reducing the voltage in each process such as the first flip, subsequent flip, write operation, and read operation, the device is kept turned on, thereby increasing the life of the device and reducing the power consumption of the device operation.

[0092] As a preferred implementation, when the first predetermined data is "1", the second predetermined data is "0"; and

[0093] When the first predetermined data is "0", the second predetermined data is "1".

[0094] Specifically, in the present embodiment, the initial data stored in the memory cell 01 after the one-time programmable read-only memory device is formed is "0" or "1", and a first write voltage Vprog1 greater than the first threshold transition voltage Vform is applied for the first time to open the memory cell 01, and then a second write voltage Vprog2 is applied to maintain the memory cell 01 being opened, thereby completing the operation of writing "1" or "0" into the memory cell 01; at the same time, before the write operation, a first read voltage Vread1 greater than the second threshold transition voltage Vth but less than the first threshold transition voltage Vform is applied to the memory cell 01 to open the memory cell 01, and then a second read voltage Vread2 is applied to maintain the memory cell 01 being opened, thereby completing the operation of reading "0" or "1" from the memory cell 01; further, after performing a write operation once, a first read voltage Vread1 greater than the second threshold transition voltage Vth but less than the first threshold transition voltage Vform is applied to open the memory cell 01, and then a second read voltage Vread2 is applied to maintain the memory cell 01 being opened, thereby completing the operation of reading "1" or "0" from the memory cell 01.

[0095] The above operation voltages satisfy: first write voltage Vprog1> first threshold transition voltage Vform> first read voltage Vread1> second threshold transition voltage Vth;

[0096] The first write voltage Vprog1> the first threshold transition voltage Vform> the second write voltage Vprog2> the first hold threshold transition voltage Vholdform;

[0097] The first readout voltage Vread1 > the second threshold transition voltage Vth > the second readout voltage Vread2 > the second holding threshold transition voltage Vhold.

[0098] As a preferred embodiment, the one-time programmable read-only memory applies a voltage across the two ends of the storage unit 01 and detects the current flowing through the storage unit 01, and completes the read operation of the storage unit 01 according to the current size;

[0099] When the memory cell 01 has not been subjected to a write operation, the current flowing through the memory cell 01 is small, and the first predetermined data is output after a read operation is performed; and

[0100] After the memory cell 01 is written into, the current flowing through the memory cell 01 is relatively large, and the second predetermined data is output after the read operation is performed.

[0101] Specifically, in this embodiment, the read operation is implemented by applying a voltage across the storage cell 01 and detecting the magnitude of the current flowing through the storage cell 01. When the storage cell 01 is in an initial state without undergoing a write operation, the current flowing through the storage cell 01 is small, and the read circuit outputs initial data "0" or "1" at this time; when the storage cell 01 is in a state after undergoing a write operation, the current flowing through the storage cell 01 is large, and the read circuit outputs initial data "1" or "0" at this time.

[0102] As a preferred embodiment, the single-element material layer 3 is made of tellurium (Te) or selenium (Se).

[0103] Specifically, in this embodiment, the single material layer 3 is made of single material such as Te or Se. Further, other single materials can also be used to prepare the single material layer 3 of the present invention.

[0104] As a preferred embodiment, the first electrode layer 1 and the second electrode layer 2 are both made of titanium nitride (TiN) or tantalum nitride (TaN).

[0105] Specifically, in this embodiment, the first electrode layer 1 is made of semiconductor materials such as titanium nitride (TiN) or tantalum nitride (TaN); the second electrode layer 2 is also made of semiconductor materials such as titanium nitride (TiN) or tantalum nitride (TaN).

[0106] Furthermore, the materials used to prepare the first electrode layer 1 and the second electrode layer 2 may be the same or different. The shapes of the prepared first electrode layer 1 and the second electrode layer 2 may be the same or different.

[0107] As a preferred embodiment, the shape of the storage unit 01 formed by the first electrode layer 1, the single material layer 3 and the second electrode layer 2 is one or more combinations of T-type, μ-type and O-type.

[0108] Specifically, in this embodiment, the first electrode layer 1, the single material layer 3 and the second electrode layer 2 of the formed storage unit 01 may be in a T-type, μ-type or O-type. Preferably, other defined types may also be used.

[0109] In the above preferred embodiment, if Figure 2 As shown, it is a schematic diagram of the electrical performance of the memory cell 01 of the one-time programmable read-only memory under different electrode sizes. When the electrode sizes of the first electrode layer 1 and the second electrode layer 2 are 60nm, 120nm, 150nm and 200nm, after the memory cell 01 of the one-time programmable read-only memory is formed, the crystalline single material layer 3 and the polycrystalline electrode layer form a Schottky junction in the absence of an external electric field, and present a high resistance. After a certain voltage (i.e., the first threshold transition voltage Vform) is applied to both ends of the memory cell 01 for the first time, the resistance value of the device decreases sharply. Taking the electrode size of 120nm as an example, at this time, the first threshold transition voltage Vform is about 2.5V, and the first holding threshold transition voltage Vholdform is about 1V; and when the voltage is removed, it returns to a high resistance state instantly; subsequently, after a certain voltage (i.e., the second threshold transition voltage Vth) is applied to both ends of the device again, the resistance value of the device decreases sharply, at this time, the second threshold transition voltage Vth is about 2V, and the second holding threshold transition voltage Vhold is about 1.3V, and when the voltage is removed, it returns to a high resistance state instantly.

[0110] The storage unit 01 of the one-time programmable read-only memory exhibits threshold switching characteristics regardless of the first voltage application or the subsequent second and m-th voltage applications, and the first threshold transition voltage Vform is much greater than the second threshold transition voltage Vth. At the same time, when the electrode size is 60nm, 120nm, 150nm and 200nm, the first threshold transition voltage Vform is maintained at about 2.5V, and the second threshold transition voltage Vth is maintained at about 2V. Therefore, during the write operation, the first write voltage Vprog1>2.5V is applied first, and then the second write voltage Vprog2 is applied, wherein 2.5V>the second write voltage Vprog2>1V, so that the write operation of the one-time programmable read-only memory can be realized; during the read operation, the first read voltage Vread1 is applied first, wherein 2.5V>>the first read voltage Vread1>2V, and then the second read voltage Vread2 is applied, wherein 2V>the second read voltage Vread2>1.3V, so that the read operation of the one-time programmable read-only memory can be realized. At the same time, since the first read voltage Vread1>1.3V, if the one-time programmable read-only memory has written programming data, the resistance of the storage unit 01 will decrease sharply and the current will increase sharply, which is conducive to quickly reading the data of the storage unit 01, and can realize the high-speed read operation of the one-time programmable read-only memory. It should be noted that as the electrode size changes, the above-mentioned operating voltage will also change accordingly. The specific operating voltage value can be determined according to actual conditions and is not limited to the embodiment of the present invention.

[0111] Embodiment 2

[0112] See also Figure 3 and Figure 4 The embodiment of the present invention also provides a one-time programmable read-only memory with a novel device structure. Compared with the first embodiment, the storage unit 01 of the one-time programmable read-only memory in the embodiment of the present invention is a cross structure, specifically presenting a cross array structure. The rest is the same as the storage unit 01 in the first embodiment, and will not be repeated here. The cross storage unit includes:

[0113] More than one memory cell 01, one of the first electrode layer 1 or the second electrode layer 2 of each memory cell 01 is respectively connected to a first metal layer 5, and the first metal layer 5 is connected to a first address line;

[0114] The second metal layer 4 is connected to the other of the first electrode layer 1 or the second electrode layer 2 of all the memory cells 01 , and the second metal layer 4 is connected to a second address line.

[0115] As a preferred embodiment, there is one between each storage unit 01 .

[0116] Specifically, in this embodiment, an isolation dielectric layer 6 is formed between each storage unit 01 by using a dielectric material such as SiN to isolate the storage units 01 and form a cross-structured storage unit 01 .

[0117] Furthermore, the first metal layer 5 and the second metal layer 4 are both made of tungsten metal (W) or other metals.

[0118] Specifically, in this embodiment, the first electrode layer 1 of the storage unit 01 is connected to the first address line of the storage array formed by the first metal layer 5, and the second electrode layer 2 is connected to the second address line of the storage array formed by the second metal layer 4; or

[0119] The first electrode layer 1 is connected to the second address line of the memory array formed by the second metal layer 4 , and the second electrode layer 2 is connected to the first address line of the memory array formed by the first metal layer 5 .

[0120] like Figure 4 As shown, the first address line and the second address line both include word lines WL or bit lines BL, and each storage unit 01 is isolated by dielectric materials such as SiN to form a cross-structured storage unit 01. When the one-time programmable read-only memory is working, the first address line (word line WL0 or bit line BL0) and the second address line (bit line BL1 or word line WL1) are controlled by the chip decoding circuit to realize the gating and operation of the storage unit 01. Figure 4 As shown, the voltage of the control word line WL1 is 0, the voltage of the bit line BL1 is Vop, and the voltages of other word lines and bit lines are all set to Vb, which can realize the selection and operation of the memory cell 01 corresponding to (WL1, BL1).

[0121] Further, when performing a read operation of the memory cell 01, Vop can be set to be slightly larger than the second threshold transition voltage Vth, but much smaller than the first threshold transition voltage Vform, and Vb can be set to be the difference between Vop and the second threshold transition voltage Vth, that is, Vth>Vb>Vop-Vth;

[0122] When performing a write operation of the memory cell 01 , Vop may be set to be slightly greater than the first threshold transition voltage Vform, and Vb may be set to be greater than the difference between Vop and the second threshold transition voltage Vth, ie, Vth>Vb>Vop−Vth.

[0123] Embodiment 3

[0124] See also Figure 5The embodiment of the present invention also provides a one-time programmable read-only memory with a stacked structure of multi-layer cross memory cells. The memory cell 01 of the embodiment of the present invention is the same as that in the first embodiment, and the cross memory cell is the same as that in the second embodiment, which will not be described in detail here. Compared with the second embodiment, the cross memory cells of the one-time programmable read-only memory in the embodiment of the present invention are stacked into N layers in the vertical direction to form a three-dimensional one-time programmable read-only memory with a storage density of 4F2 / N;

[0125] Wherein, F is the characteristic dimension of the semiconductor process, and N is a natural number greater than or equal to 2.

[0126] Specifically, the one-time programmable read-only memory provided by the embodiment of the present invention is formed by stacking multiple layers of cross memory cells. Figure 5 As shown, a one-time programmable read-only memory with a stacked structure of two layers of cross memory cells is shown, wherein the cross memory cells are stacked in two layers (FL.1, FL.2) in a vertical direction to form a storage density of 2F 2 A three-dimensional one-time programmable read-only memory is provided, wherein F is a feature size of a semiconductor process. The first layer FL.1 and the second layer FL.2 share a second address line (including a bit line BL1 or a word line WL1).

[0127] Furthermore, when the three-dimensional one-time programmable read-only memory is working, the chip decoding circuit controls the first address line (word line WL0 or bit line BL0) and the second address line (bit line BL1 or word line WL1) to realize the gating and operation of the storage unit 01. Among them, the word line voltage of the storage unit 01 to be selected is controlled to be 0, the bit line voltage is Vop, and the other word line and bit line voltages are set to Vb.

[0128] When performing a read operation of the memory cell 01, Vop can be set to be slightly larger than the second threshold transition voltage Vth, but much smaller than the first threshold transition voltage Vform, and Vb can be set to be the difference between Vop and the second threshold transition voltage Vth, that is, Vth>Vb>Vop-Vth;

[0129] When performing a write operation of the memory cell 01 , Vop may be set to be slightly greater than the first threshold transition voltage Vform, and Vb may be set to be greater than the difference between Vop and the second threshold transition voltage Vth, ie, Vth>Vb>Vop−Vth.

[0130] Embodiment 4

[0131] The embodiment of the present invention further provides a method for writing into a one-time programmable read-only memory, which is used to write into the one-time programmable read-only memory in the above-mentioned embodiment 1, embodiment 2 and embodiment 3 to achieve the purpose of "programming" the one-time programmable read-only memory. The specific writing method is as follows:

[0132] When performing a write operation, a first write voltage is first applied to both ends of the memory cell to open the memory cell; then a second write voltage is applied to keep the memory cell open and complete the write operation;

[0133] Vprog1>Vform>Vprog2>Vholdform;

[0134] Wherein, Vprog1 is the first write voltage;

[0135] Vform is the first threshold transition voltage;

[0136] Vprog2 is the second write voltage;

[0137] Vholdform is the first hold threshold transition voltage that maintains the memory cell flipping when the voltage is first applied.

[0138] Specifically, in this embodiment, when the storage unit 01 undergoes a threshold flip for the first time, that is, when a voltage is applied for the first time, its first threshold transition voltage Vform is greater than the first threshold transition voltage Vholdform for maintaining the flip of the storage unit. According to this characteristic, when the storage unit 01 performs a write operation for the first time, the specific operation process includes: first using the first write voltage Vprog1 to open the storage unit 01, then using the second write voltage Vprog2 to keep the storage unit 01 open, and completing the write operation. This embodiment increases the life of the device and reduces the power consumption of the device operation by reducing the write voltage after opening the storage unit 01.

[0139] Embodiment 4

[0140] The embodiment of the present invention further provides a method for reading a one-time programmable read-only memory, which is used to read the one-time programmable read-only memory in the above-mentioned embodiment 1, embodiment 2 and embodiment 3. The specific reading method is as follows:

[0141] When performing a read operation, a first read voltage is first applied to both ends of the memory cell to open the memory cell; a second read voltage is then applied to keep the memory cell open, amplify the current flowing through the memory cell, and complete the read operation;

[0142] Vread1>Vth>Vread2>Vhold;

[0143] Wherein, Vread1 is the first read voltage;

[0144] Vth is the second threshold transition voltage;

[0145] Vread2 is the second read voltage;

[0146] Vhold is a second sustain threshold transition voltage for maintaining the memory cell flipping when a voltage is subsequently applied.

[0147] Specifically, in this embodiment, the storage cell 01 undergoes a threshold flip again after the first "programming" operation, that is, when a voltage is subsequently applied, its second threshold transition voltage Vth is greater than the second threshold transition voltage Vhold for maintaining the flip of the storage cell. According to this characteristic, when the storage cell 01 performs a read operation, the specific operation process includes: first using the first read voltage Vread1 to open the storage cell 01, then using the second read voltage Vead2 to keep the storage cell 01 open, using the read circuit to amplify the current flowing through the storage cell 01, and completing the read operation. This embodiment increases the life of the device and reduces the power consumption of the device operation by reducing the read voltage after opening the storage cell 01.

[0148] The adoption of the above technical solution has the following advantages or beneficial effects: the one-time programmable read-only memory of the present invention not only has a threshold switch function, but also has the advantages of a storage function, low static power consumption, simple structure, low process requirements, three-dimensional integration and three-dimensional miniaturization, and is suitable for a cross array structure, especially a high-density three-dimensional one-time programmable read-only memory; at the same time, the life of the device is increased and the device operating power consumption is reduced.

[0149] Through the description and drawings, typical embodiments of the specific structures of the specific implementation methods are given, and other transformations can be made based on the spirit of the present invention. Although the above invention proposes the existing preferred embodiments, these contents are not intended to be limiting.

[0150] For those skilled in the art, various changes and modifications will undoubtedly be obvious after reading the above description. Therefore, the attached claims should be regarded as covering all changes and modifications of the true intent and scope of the present invention. Any and all equivalent ranges and contents within the scope of the claims should be considered to still be within the intent and scope of the present invention.

Claims

1. A one-time programmable read-only memory, characterized in that: A storage unit is included, wherein the storage unit includes: A first electrode layer, a second electrode layer, and a single material layer between the first electrode layer and the second electrode layer, wherein the single material layer is made of tellurium or selenium; The formed memory cell exhibits high resistance in the absence of an external electric field, and the memory cell has: a first threshold transition voltage, the first threshold transition voltage being a flip voltage when the memory cell is converted from a high resistance to a low resistance when a voltage is first applied; a second threshold transition voltage, the second threshold transition voltage being a flip voltage when the memory cell is converted from a high resistance to a low resistance when a voltage is subsequently applied; wherein the first threshold transition voltage is greater than the second threshold transition voltage; The storage unit also has: a first write voltage, wherein the first write voltage is greater than the first threshold transition voltage; a first readout voltage, the first readout voltage being greater than the second threshold transition voltage, and the first readout voltage being less than the first threshold transition voltage.

2. The one-time programmable read-only memory according to claim 1, characterized in that: The storage unit is a cross structure, and the cross storage unit includes: More than one storage unit, one of the first electrode layer or the second electrode layer of each storage unit is connected to a first metal layer, and the first metal layer is connected to a first address line; A second metal layer, wherein the second metal layer is connected to the other of the first electrode layer or the second electrode layer of all the memory cells, and the second metal layer is connected to a second address line.

3. The one-time programmable read-only memory according to claim 2, characterized in that: The cross memory cells are stacked in N layers in the vertical direction to form a storage density of 4F 2 / N three-dimensional one-time programmable read-only memory; Wherein, F is the characteristic dimension of the semiconductor process, and N is a natural number greater than or equal to 2.

4. The one-time programmable read-only memory according to any one of claims 1 to 3, characterized in that: The single material layer forms a single crystal thin film on the first electrode layer and the second electrode layer; and / or the single material layer forms a single crystal thin film on an amorphous substrate; At the same time, the single material layer forms a Schottky junction with the first electrode layer and the second electrode layer respectively.

5. The one-time programmable read-only memory according to any one of claims 1 to 3, characterized in that: The memory cell exhibits high resistance after being formed, and after a predetermined voltage signal is applied to both ends of the memory cell, the memory cell is instantly changed from a high resistance state to a low resistance state; as well as When the predetermined voltage signal is removed, the storage unit is instantly converted back to a high-impedance state, exhibiting a threshold switching characteristic.

6. The one-time programmable read-only memory according to any one of claims 1 to 3, characterized in that: The storage unit also includes: a second write voltage for maintaining the memory cell open after the first write voltage is applied to open the memory cell, the second write voltage being less than the first threshold transition voltage and greater than a first maintain threshold transition voltage, the first maintain threshold transition voltage being a voltage that maintains the memory cell from high resistance to low resistance when the voltage is first applied; a second read voltage for maintaining the memory cell open after the first read voltage is applied to open the memory cell, the second read voltage being less than the second threshold transition voltage, and the second read voltage being greater than a second sustaining threshold transition voltage, the second sustaining threshold transition voltage being a voltage that maintains the memory cell from a high resistance to a low resistance when a voltage is subsequently applied; The initial data stored in the storage unit after being formed is the first predetermined data, the first write voltage is applied first, and then the second write voltage is applied to complete the operation of writing the second predetermined data; The memory cell first applies the first read voltage and then applies the second read voltage before performing a write operation to complete an operation of reading the first predetermined data; and After the writing operation is performed on the memory cell, the first read voltage is first applied, and then the second read voltage is applied to complete the operation of reading the second predetermined data.

7. The one-time programmable read-only memory according to any one of claim 6, characterized in that: The one-time programmable read-only memory applies a voltage to both ends of the memory cell and detects the current flowing through the memory cell, thereby completing the read operation of the memory cell according to the magnitude of the current; When the storage unit has not been subjected to a write operation, the current flowing through the storage unit is small, and the first predetermined data is output after a read operation is performed; as well as After the memory cell is written into, the current flowing through the memory cell is relatively large, and the second predetermined data is output after the read operation is performed.

8. The one-time programmable read-only memory according to claim 6, characterized in that: When the first predetermined data is "1", the second predetermined data is "0"; and When the first predetermined data is "0", the second predetermined data is "1".

9. The one-time programmable read-only memory according to any one of claims 1 to 3, characterized in that: The first electrode layer and the second electrode layer are both made of titanium nitride or tantalum nitride.

10. The one-time programmable read-only memory according to any one of claims 1 to 3, characterized in that: The storage unit formed by the first electrode layer, the single material layer and the second electrode layer has a shape of one or more combinations of T-type, μ-type and O-type.

11. The one-time programmable read-only memory according to any one of claims 1 to 3, characterized in that: An isolation dielectric layer is provided between each of the storage units.

12. A method for writing into a one-time programmable read-only memory, used to implement the one-time programmable read-only memory according to any one of claims 1 to 11, characterized in that: include: When performing a write operation, a first write voltage is first applied to both ends of the memory cell to open the memory cell; Applying a second write voltage to keep the memory cell open and complete the write operation; The first write voltage, the first threshold transition voltage, the second write voltage and the first hold threshold transition voltage have the following relationship: Vprog1>Vform>Vprog2>Vholdform; Wherein, Vprog1 is the first write voltage; Vform is the first threshold transition voltage; Vprog2 is the second write voltage; Vholdform is the first holding threshold transition voltage.

13. A method for reading a one-time programmable read-only memory, used to implement the one-time programmable read-only memory according to any one of claims 1 to 11, characterized in that: include: When performing a read operation, a first read voltage is first applied to both ends of the memory cell to open the memory cell; Then applying a second read voltage to keep the memory cell open, amplify the current flowing through the memory cell, and complete the read operation; The first readout voltage, the second threshold transition voltage, the second readout voltage and the second sustain threshold transition voltage have the following relationship: Vread1>Vth>Vread2>Vhold; Wherein, Vread1 is the first read voltage; Vth is the second threshold transition voltage; Vread2 is the second read voltage; Vhold is the second hold threshold transition voltage.

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