Phase change film containing embedded nanometer heating electrode and phase change memory

Abstract

The invention belongs to the technical field of memories in the micro-nano electronic technology, and particularly relates to a phase change film containing an embedded nano heating electrode and a phase change memory. According to the phase change film containing the embedded nano heating electrode, the compound electrode material and the phase change material are co-doped by adopting a conventional doping process and then are subjected to pulse treatment, so that the compound electrode material spontaneously forms a bond to form the embedded nano heating electrode, and the local current density in the phase change film of the device is regulated and controlled; the heat production efficiency of the phase-change film is increased, the heat loss of the device is reduced, and the power consumption of the device is reduced. Meanwhile, the embedded nano heating electrode can effectively hinder migration of atoms in the phase change material, reduce structural relaxation and element segregation of the phase change material, and improve the cycle performance of the device. The method breaks through the limitation of the process, effectively reduces the size of the heating electrode, is simple in process step, obviously reduces the operation power consumption of the device, and greatly improves the cycle performance.

Description

Technical Field

[0001] The present application belongs to the field of memory technology in micro-nanoelectronics technology, and more specifically, relates to a phase change film and a phase change memory containing an embedded nano heating electrode. Background Art

[0002] The surge in data volumes and the increase in transmission and processing speeds are placing new demands on information storage technologies. Chalcogenide-based phase change memory (PCM), a promising candidate for next-generation non-volatile memory, offers outstanding advantages such as high access speed, high cycle endurance, good scalability, and the potential for high integration.

[0003] The operating principle of PCM is to achieve storage functionality based on the significant resistance difference between the crystalline and amorphous states of phase change materials. In the crystalline state, the internal atoms are arranged regularly, and the phase change material exhibits low resistivity, representing a "1" in binary. In the amorphous state, the internal atoms are arranged disorderly, and the material exhibits high resistivity, representing a "0" in binary. Typically, electric pulses are used to induce a thermal effect in the functional layer of the PCM device, causing the temperature in the local area to rapidly rise to a specific threshold transition temperature, causing the phase change material in the functional layer to undergo a structural transition between the crystalline and amorphous states. However, problems such as high power consumption during operation and poor cycle durability have severely limited its further development.

[0004] To address the problem of poor cycle performance of phase change memory, the current main methods are to reduce the void concentration of the material by doping atoms and to use a multi-layer structure to prevent element segregation.

[0005] The operating power consumption of phase change memory is closely related to the size of the phase change region. The smaller the phase change region, the lower the operating power consumption of the device. Currently, the current density in the phase change layer is mainly regulated by using small-sized heating electrodes or nano-current channels, thereby reducing the phase change region and ultimately improving the heating efficiency of the device. However, nano-current channels face the challenges of consistency issues and limited erase and write cycles in large-scale integrated circuits, and heating electrodes are difficult to achieve nano-scale dimensions under conventional process conditions. Realizing nano-scale heating electrodes requires a higher process or nanowire electrode structure, which has problems such as complex process, high difficulty and high cost.

[0006] Therefore, how to effectively control the current density in the phase change layer without changing the device structure under simple and efficient conventional process conditions, thereby reducing the power consumption of the phase change memory device and improving the device cycle characteristics, while taking into account the manufacturing cost and device service life, is an urgent problem to be solved in this field. Summary of the Invention

[0007] In response to the defects of the existing technology, the purpose of this application is to provide a phase change film and phase change memory containing embedded nano-heating electrodes, aiming to solve the problems of the existing process of preparing low-operating power consumption phase change memory, such as complex process, high difficulty, high cost and poor device cycle performance.

[0008] To achieve the above objectives, in a first aspect, the present application provides a phase change film containing an embedded nano-heating electrode, which is a phase change film prepared by co-doping a compound electrode material and a phase change material and then subjecting the resultant to a pulse treatment; The bonding ability between the atoms of the compound electrode material is stronger than the bonding ability between the atoms of the compound electrode material and the atoms of the phase change material, and the atoms can spontaneously bond to form an embedded nano-heating electrode under the operation of the pulse treatment.

[0009] Preferably, the compound electrode material includes one or more of TiC, RuO2, Mo2C and TiN.

[0010] Preferably, the atomic ratio of the compound electrode material in the phase change film is 10% to 40%.

[0011] Preferably, the phase change material includes one or more of a Sb-Te system phase change material and a Ge-Sb-Te system phase change material.

[0012] Preferably, the above-mentioned Sb-Te system phase change material includes one or more of SbTe, Sb2Te, Sb4Te and Sb2Te3.

[0013] Preferably, the above-mentioned Ge-Sb-Te system phase change material includes one or more of Ge2Sb2Te5, Ge1Sb4Te7, Ge1Sb2Te4 and Ge4Sb6Te7.

[0014] Preferably, the co-doping method includes one or more of magnetron co-sputtering, electron beam evaporation, atomic layer deposition, chemical vapor deposition or electroplating.

[0015] Preferably, the pulse is a voltage pulse.

[0016] In a second aspect, the present application provides a phase change memory, comprising a substrate, and at least one phase change memory unit disposed on the substrate, wherein the phase change memory unit comprises a lower electrode, an insulating layer, the phase change film, and an upper electrode; The lower electrode is located on the lower surface of the phase change film; the upper electrode is located on the upper surface of the insulating layer of the phase change film; and the insulating layer is located around the phase change film.

[0017] Preferably, the phase change film has a confined structure or a mushroom structure.

[0018] Preferably, the material of the lower electrode and the upper electrode are independently one or more of Pt, Ti, TiN, W, Au, Ag, Al and Cu.

[0019] Preferably, the material of the insulating layer is SiO2, Al2O3, AlN, Si3N4 or BN.

[0020] Preferably, the thickness of the lower electrode and the upper electrode are independently 10 nm to 400 nm.

[0021] Preferably, the thickness of the insulating layer is 2 nm to 400 nm.

[0022] Preferably, the thickness of the phase change film is 2 nm to 400 nm.

[0023] In general, the above technical solutions conceived by this application have the following technical advantages compared with the existing technologies: (1) The phase change film containing embedded nano-heating electrodes provided in this application is a process in which a compound electrode material and a phase change material are co-doped by a conventional doping process and then pulse-treated, so that the compound electrode material spontaneously bonds to form an embedded nano-heating electrode. This effectively reduces the size of the heating electrode, enables the regulation of the current density within the phase change film of the device, improves the efficiency of electric and thermal utilization during device operation, significantly reduces device heat loss, and thus reduces device power consumption. At the same time, the embedded nano-heating electrode can effectively hinder the migration of atoms in the phase change material, reduce the structural relaxation and element segregation of the phase change material, and improve the cycle performance of the device.

[0024] (2) Compared with the existing phase change memory in which the heating electrode is placed on the lower surface of the phase change film layer, the present application adopts conventional preparation process to realize the preparation of nano-scale electrodes, which reduces the preparation process of the phase change memory device and reduces the complexity of the process. In addition, the embedded nano heating electrode has good compatibility with the preparation process of the phase change memory, which has the advantage of simple process while improving the performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 RT curves of the TiN-Ge1Sb4Te7 phase change film and the Ge1Sb4Te7 phase change film prepared in the examples of the present application; Figure 2 This is the XPS test result of Ti atoms in the TiN-Ge1Sb4Te7 phase change film prepared in the embodiment of the present application; FIG3 (a) is a model of a crystalline Ge1Sb4Te7 phase change material film constructed in an embodiment of the present application; FIG3( b ) is a model of an amorphous Ge1Sb4Te7 phase change material film constructed in an embodiment of the present application; FIG3 (c) is a model of an amorphous Ge1Sb4Te7 phase change material film with TiN unit cells added, constructed in an embodiment of the present application; FIG3 (d) is a model of an amorphous TiN-Ge1Sb4Te7 phase change material film constructed in an embodiment of the present application; FIG4 (a) is a calculation result of the pair distribution function of the N—X bond of the TiN-Ge1Sb4Te7 amorphous model in the embodiment of the present application; FIG4( b ) is a calculation result of the pair distribution function of the Ti-X bond of the TiN-Ge1Sb4Te7 amorphous model in the embodiment of the present application; Figure 5 This is a schematic diagram of the structure of a phase change memory unit containing a phase change material with embedded nanoelectrodes provided in an embodiment of the present application; FIG6 (a) is a cross-sectional microstructure diagram of a Ge1Sb4Te7 phase change memory device containing TiN embedded nanoelectrodes provided in an embodiment of the present application; FIG6 (b) is an EDS test diagram of Ti and N elements in the deposited device provided in an embodiment of the present application; FIG6 (c) is an EDS test diagram of Ti and N elements in a SET state device provided in an embodiment of the present application; FIG6 (d) is an EDS test diagram of Ti and N elements in a RESET state device provided by an embodiment of the present application; Figure 7 RV curves of the Ge1Sb4Te7 phase change memory containing TiN embedded nanoelectrodes and the RESET process of the Ge1Sb4Te7 phase change memory prepared in the embodiment of the present application; FIG8 (a) is a cycle characteristic test diagram of a Ge1Sb4Te7 phase change memory provided in an embodiment of the present application; FIG8( b ) is a test diagram of the cycle characteristics of the Ge1Sb4Te7 phase change memory containing TiN embedded nanoelectrodes provided in an embodiment of the present application; Figure 9 The structural model of the Ge1Sb4Te7 phase change memory used in the electrothermal simulation of the device according to the present application (left) and the structural model of the Ge1Sb4Te7 phase change memory containing TiN embedded nanoelectrodes (right); FIG10( a ) is a diagram showing the temperature distribution simulation results of a Ge1Sb4Te7 phase change memory cell provided in an embodiment of the present application; FIG10( b ) is a diagram showing the temperature distribution simulation results of a Ge1Sb4Te7 phase change memory cell containing TiN embedded nanoelectrodes provided in an embodiment of the present application; FIG10( c ) is a diagram showing the simulation results of the current density distribution of the Ge1Sb4Te7 phase change memory provided in an embodiment of the present application; FIG10( d ) is a diagram showing the simulation results of the current density distribution of the Ge1Sb4Te7 phase change memory device containing TiN embedded nanoelectrodes provided in an embodiment of the present application; In all drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 - substrate; 2 - lower electrode; 3 - insulating layer; 4 - phase change film; 5 - embedded nano-heating electrode; 6 - upper electrode. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0027] In the description of this application, it should be understood that the term "and / or" describes an association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The symbol " / " herein indicates that the associated objects are in an "or" relationship, for example, A / B means either A or B.

[0028] In the description of the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0029] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more.

[0030] The present application provides a phase change film containing an embedded nano-heating electrode, which is a phase change film prepared by co-doping a compound electrode material and a phase change material and then subjecting it to pulse treatment; The bonding ability between the atoms of the compound electrode material is stronger than the bonding ability between the atoms of the compound electrode material and the atoms of the phase change material, and the atoms can spontaneously bond to form an embedded nano-heating electrode under the operation of the pulse treatment.

[0031] The embedded nano-heating electrodes contained in the phase-change film provided by this application have the characteristics of high melting point and high conductivity. They can regulate the current density within the phase-change film of the phase-change memory device, improve the electrothermal utilization efficiency during device operation, act as local heating electrodes, reduce device heat loss, and thus reduce device power consumption. At the same time, the embedded nano-heating electrodes can hinder the migration of atoms in the phase-change material, reduce the structural relaxation and element segregation of the phase-change material, and improve the device's cycling performance. In addition, by embedding the nano-heating electrodes in the phase-change film, this application effectively reduces the size of the heating electrodes without requiring a higher process, reducing the complexity of the phase-change memory preparation process and the device's operating power consumption.

[0032] In some embodiments, the compound electrode material has a higher melting point and higher electrical conductivity than the phase change material. In some embodiments, the compound electrode material includes one or more of TiC, RuO2, Mo2C, and TiN.

[0033] In some embodiments, the atomic ratio of the compound electrode material in the phase change film is 10% to 40%.

[0034] In some embodiments, the phase change material includes one or more of a Sb-Te system phase change material and a Ge-Sb-Te system phase change material.

[0035] In some embodiments, the above-mentioned Sb-Te system phase change material includes but is not limited to one or more of SbTe, Sb2Te, Sb4Te and Sb2Te3.

[0036] In some embodiments, the above-mentioned Ge-Sb-Te system phase change material includes but is not limited to one or more of Ge2Sb2Te5, Ge1Sb4Te7, Ge1Sb2Te4 and Ge4Sb6Te7.

[0037] In some embodiments, the co-doping method includes one or more of magnetron co-sputtering, electron beam evaporation, atomic layer deposition, chemical vapor deposition, or electroplating.

[0038] In some embodiments, the above-mentioned magnetron co-sputtering method can be co-sputtering the compound electrode material alloy target and the phase change material target, or co-sputtering the individual single element metal targets in the compound electrode material and the phase change material target; or directly sputtering the phase change material doped target containing the elements in the compound electrode material.

[0039] In some embodiments, the pulse is a voltage pulse.

[0040] On the other hand, the present application also provides a phase change memory, which includes a substrate and at least one phase change memory unit provided on the substrate; the phase change memory unit includes a lower electrode, an insulating layer, the phase change film and an upper electrode; The lower electrode is located on the lower surface of the phase change film; the upper electrode is located on the upper surface of the insulating layer of the phase change film; and the insulating layer is located around the phase change film.

[0041] In some embodiments, the phase change film has a confined structure or a mushroom structure.

[0042] In some embodiments, the material of the lower electrode and the upper electrode is independently one or more of Pt, Ti, TiN, W, Au, Ag, Al, and Cu; the material of the insulating layer is SiO2, Al2O3, AlN, Si3N4, or BN. In some embodiments, the thickness of the lower electrode and the upper electrode is independently 10nm to 400nm; the thickness of the insulating layer is 2nm to 400nm; and the thickness of the phase change film is 2nm to 400nm.

[0043] It should be understood that materials of the same or similar type, model, quality, properties, or functions as the reagents and instruments used in the following examples can be used to implement this application. The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources.

[0044] The following are examples and comparative examples: Example 1 This embodiment provides a Ge1Sb4Te7 phase change film containing a TiN embedded nano-heating electrode, hereinafter referred to as the TiN-Ge1Sb4Te7 phase change film. As shown in Table 1, Ti atoms and N atoms have strong bonding characteristics and low formation energy, while Ti atoms and N atoms have high bonding energy with atoms in Ge1Sb4Te7. Therefore, Ti atoms and N atoms are more likely to bond in the Ge1Sb4Te7 system to form a TiN embedded nano-heating electrode structure. Secondly, TiN has high electrical conductivity (2.5×10 5 S / m), whose melting point (2950℃) is higher than that of Ge1Sb4Te7 (about 600℃), and the embedded nano-heating electrode formed is not easy to decompose at high temperature.

[0045] Table 1 Formation energy (ev / atom)

[0046] More specifically, the TiN-Ge1Sb4Te7 phase change film is prepared by magnetron sputtering, and the process includes the following steps: S1: Use a silicon wafer cutting knife to cut the SiO2 / Si substrate into a size of 2 cm × 2 cm.

[0047] S2: Add a small amount of acetone to a beaker, immerse the cut substrate in the acetone, and then place it in an ultrasonic cleaning device. Clean the substrate at 40 W power for 3 minutes to remove surface contaminants.

[0048] S3: Pour an appropriate amount of alcohol into another beaker, transfer the substrate cleaned with acetone into it, and continue ultrasonic cleaning at the same power for about 5 minutes.

[0049] S4: Use deionized water to wash away the ethanol on the substrate, and finally use a nitrogen gun to blow dry.

[0050] S5: Open the reaction chamber and sample loading chamber of the magnetron sputtering instrument. Place the TiN target and Ge1Sb4Te7 target in the AC sputtering target position and the DC sputtering target position, respectively. After securing them, use a multimeter to check whether the inner and outer walls of the sputtering target positions are short-circuited. Attach the substrate to the carrier plate with high-temperature resistant adhesive, and then place the carrier plate into the sample loading chamber robot.

[0051] S6: Close the reaction chamber and the sample chamber, and start the "automatic control" process. Set the sputtering vacuum to 1×10 -4 Pa, the input argon flow rate was 60 sccm, and the reaction chamber pressure was set to 0.5 Pa. The AC sputtering target power for TiN was set to 35 W with a duty cycle of 100%, and the DC sputtering target power for Ge1Sb4Te7 was set to 30 W. Pre-sputtering was used to remove oxide impurities on the target surface for 100 s, and the sputtering duration was set to 300 s.

[0052] S7: The "automatic control" program is started, completing the following steps: cleaning, feeding, vacuum pumping, pre-sputtering, voltage regulation, ignition, pause, vacuum pumping, and opening the sample chamber. This results in a Ge1Sb4Te7 phase-change thin film containing TiN-embedded nanoheating electrodes, known as a TiN-Ge1Sb4Te7 phase-change thin film. The film is approximately 100 nm thick and contains approximately 23% TiN.

[0053] Comparative Example 1 This comparative example provides a Ge1Sb4Te7 phase change film prepared by magnetron sputtering. The preparation method is the same as that of Example 1, except that the AC sputtering power of the TiN target is set to 0 W, that is, no TiN target is sputtered.

[0054] The crystallization temperature test (RT test) was performed on the TiN-Ge1Sb4Te7 phase change film prepared in Example 1 and the Ge1Sb4Te7 phase change film prepared in Comparative Example 1. The test steps are as follows: The prepared film sample is cut into an appropriate size (approximately 1.5 cm × 1.5 cm) using a silicon wafer knife and placed in a temperature-controlled probe station, with the test probe approximately 1 cm away from the film surface. The temperature-controlled probe station is then completely sealed and high-purity nitrogen is introduced into it to prevent oxidation of the film sample during heating, which would reduce the accuracy of the test results. Then, using the temperature-controlled heating system, the probe station is set to quickly reach 50°C and then heated to 300°C at a rate of 18°C / min. The resistance value of the film sample is recorded in real time starting at 50°C. When reading the resistance, the reading voltage is 0.1V and the reading interval is 1 s.

[0055] Figure 1 The figure shows the change of resistance of the phase change film with temperature. It can be seen that the crystallization temperature of the Ge1Sb4Te7 phase change film (GST) is 130.4 ℃, and the crystallization temperature of the TiN-Ge1Sb4Te7 phase change film (TiN-GST) is 210.2 ℃. This result shows that the introduction of highly stable Ti-N bonds can greatly increase the crystallization temperature of the phase change film and improve the thermal stability of the amorphous film.

[0056] XPS test was performed on the TiN-Ge1Sb4Te7 phase change film prepared in Example 1.

[0057] Figure 2 This is the XPS test image of Ti atoms in TiN-Ge1Sb4Te7 phase change film. It can be seen that Ti atoms in TiN-Ge1Sb4Te7 phase change film mainly show 2p 3 / 2 , 2p and 2p 1 / 2 The binding energies of the electron orbitals are 455.5 eV, 457.6 eV, and 461 eV, respectively, corresponding primarily to the binding energies of Ti-N bond formation. XPS results further confirm that in the TiN-Ge1Sb4Te7 system, Ti atoms selectively bond with N atoms to form TiN nanoclusters.

[0058] Example 2 This embodiment provides a method for constructing a Ge1Sb4Te7 phase change film model containing TiN embedded nano-heating electrodes. The TiN-Ge1Sb4Te7 and Ge1Sb4Te7 phase change film materials are modeled separately using Materials Studio software. The two models are subjected to a melting and quenching process using first-principles calculations to obtain amorphous models of the two materials.

[0059] More specifically, a crystalline model of the Ge1Sb4Te7 phase-change film was first constructed, as shown in Figure 3(a). The model was then maintained at 2000 K for 10 ps using first-principles calculations, with a time step of 4 fs, to ensure that the material completely molten. To accelerate the melting process, the applied temperature was significantly above the melting point of the material, effectively shortening the time required to reach the molten state. Subsequently, the temperature was rapidly lowered to 300 K at a cooling rate of 170 k / ps to achieve rapid quenching. During the quenching process, the atoms were unable to arrange themselves in a regular pattern, resulting in an amorphous structure. The quenched model was then subjected to a constant temperature treatment at 300 K for 3 ps to stabilize the amorphous model, as shown in Figure 3(b). The atomic arrangement in the amorphous model of Ge1Sb4Te7 exhibits short-range disorder, consistent with the definition of an amorphous structure.

[0060] Next, an amorphous model of TiN-Ge1Sb4Te7 was constructed. Since the experiment used magnetron sputtering to prepare thin films and devices, and the samples prepared by magnetron sputtering are usually amorphous, the unit cell structure of TiN was randomly added to the amorphous model of Ge1Sb4Te7, as shown in Figure 3 (c). After that, the above-mentioned high-temperature melting and rapid quenching process was carried out to obtain the amorphous model of TiN-Ge1Sb4Te7, as shown in Figure 3 (d). It can be seen that the Ti atoms and N atoms in the amorphous model of TiN-Ge1Sb4Te7 gradually connect with each other to form TiN nanoclusters, indicating that TiN has an obvious tendency to form an embedded nano-heating electrode structure in the Ge1Sb4Te7 system.

[0061] Figure 4 (a) and Figure 4 (b) are the calculated results of the pair distribution function of the NX bond and the Ti-X bond (X is N, Ti, Ge, Sb or Te) in TiN-Ge1Sb4Te7. It can be seen that in the amorphous model of TiN-Ge1Sb4Te7, Ti atoms are mainly bonded with N atoms, and only a small amount of Ti atoms are bonded with N atoms and other atoms in the Ge1Sb4Te7 system. Moreover, the bond length of the Ti-N bond is shorter than that of some major bonds in the system, and it is easy to form a compact TiN cluster, which is conducive to the formation of an embedded nano-heating electrode structure in the Ge1Sb4Te7 system.

[0062] Example 3 This embodiment provides a phase change memory based on TiN-Ge1Sb4Te7 phase change memory material, and its structural diagram is shown in FIG. Figure 5 As shown, it includes a substrate 1, a lower electrode layer 2, an insulating layer 3, a phase change film 4 containing embedded nano-heating electrodes 5, and an upper electrode layer 6 arranged on the substrate from bottom to top. The preparation process of the phase change memory includes the following steps: S1. Prepare a dry, neat substrate with a size of 3 cm × 3 cm.

[0063] S2, using magnetron sputtering process, a 100 nm thick Pt film was prepared on the substrate surface as the lower electrode. In terms of the parameter setting of magnetron sputtering, the background vacuum was set to 1×10 -4 Pa, argon flow rate was 40 sccm, pressure was 0.5 Pa, Ti target DC sputtering power was 40 W, sputtering time was 200 s, Pt target DC sputtering power was 40 W, sputtering time was 800 s.

[0064] S3. Use PECVD to deposit 100 nm thick SiO2 as an insulating layer on the Pt lower electrode.

[0065] S4. Spin-coat ARP 6200 positive photoresist on the SiO2 insulating layer and transfer the pattern of the lower electrode and aperture array onto the insulating layer using EBL. The lower electrode structure is designed to be a 100 μm × 100 μm square.

[0066] S5. Use ICP technology to etch the SiO2 insulating layer. The etching gases are CF4 and O2. The etching time is 38 s to ensure that the through hole formed by etching can penetrate to the lower electrode.

[0067] S6. After etching is completed, immerse the device in a degumming solution for 12 h to dissolve the remaining photoresist.

[0068] S7. After stripping, spin-coat AZ 5214 photoresist onto the device insulating layer. Transfer the top electrode array pattern to the insulating layer using UV photolithography. The top electrode array is designed to be 10×10, with a single top electrode pattern being a 150 μm×150 μm square, centered on the aperture array.

[0069] S8. A TiN-Ge1Sb4Te7 phase change film with a thickness of 100 nm is deposited in the small hole by the magnetron sputtering method provided in Example 1, and then a Pt film with a thickness of 100 nm is deposited as the upper electrode.

[0070] S9. After the upper electrode is prepared, acetone is used to remove the photoresist on the surface of the device. After cleaning and drying, the preparation of the phase change memory device is completed.

[0071] The phase-change memory device based on the TiN-Ge1Sb4Te7 phase-change thin film was microscopically characterized, and the cross-sectional microstructure of the device is shown in Figure 6(a). EDS measurements were then performed on the central region of the TiN-Ge1Sb4Te7 device in the as-deposited, SET, and RESET states. Figures 6(b), 6(c), and 6(d) show that the Ti and N elements are uniformly distributed in the as-deposited device, while they are enriched in localized regions in the SET and RESET devices. This indicates that after the pulse operation, Ti and N atoms selectively form bonds in the system due to the strong Ti-N bond interaction, thereby forming an embedded nanoheating electrode structure.

[0072] Comparative Example 2 This comparative example provides a phase change memory based on Ge1Sb4Te7 phase change memory material. The preparation method is the same as that in Example 3, except that in step S8, Ge1Sb4Te7 phase change material with a thickness of 100 nm is deposited in the small hole by magnetron sputtering, and then 100 nm of Pt is deposited as the upper electrode.

[0073] The electrical properties of the phase change memory based on Ge1Sb4Te7 phase change memory material containing TiN embedded nano-heating electrodes prepared in Example 3 and the phase change memory based on Ge1Sb4Te7 phase change memory material prepared in Comparative Example 2 were tested.

[0074] Figure 7 This is the RV test diagram of the phase change memory RESET process. It can be seen that under a pulse width of 20 ns, when the voltage amplitude increases to 1.4 V, the Ge1Sb4Te7 device (GST) changes from the initial low resistance state to the high resistance state, and the device completes the RESET process. The TiN-Ge1Sb4Te7 device (TiN-GST) can complete the RESET process when the voltage amplitude increases to 0.8 V. According to the power consumption calculation formula: The TiN-Ge1Sb4Te7 device achieved a RESET power consumption as low as 0.53 pJ, a 95% reduction compared to the Ge1Sb4Te7 device (13.98 pJ). This result demonstrates that a phase-change memory fabricated using Ge1Sb4Te7 phase-change memory material with TiN-embedded nanoheating electrodes as a phase-change thin film exhibits low RESET power consumption. This application provides a feasible approach for fabricating low-power phase-change memories.

[0075] Figure 8 (a) shows the cycling performance of the Ge1Sb4Te7 device (GST). It can be seen that the number of cycles of the Ge1Sb4Te7 device can only reach 8×10 4Figure 8 (b) shows the cycling performance of the TiN-Ge1Sb4Te7 device (TiN-GST). It can be seen that the cycle number of the TiN-Ge1Sb4Te7 device reaches 6.1×10 8 Compared with the Ge1Sb4Te7 device, the cycle number of the TiN-Ge1Sb4Te7 device increased by 3 orders of magnitude. This result shows that the TiN embedded nano-heating electrode structure can effectively improve the cycle performance of the device.

[0076] Example 4 This embodiment performs finite element simulation on the RESET process of a phase change memory structure containing an embedded nano-heating electrode and a traditional phase change memory structure.

[0077] More specifically, the simulation is based on a three-layer phase change memory cell structure, where the top layer is the upper electrode, the center area of ​​the middle layer is the phase change material, the two sides are insulating materials, and the bottom layer is the bottom electrode. The phase change material is divided horizontally and vertically into 250 small squares, such as Figure 9 As shown (left), randomly select small squares to fill with compound electrode materials. In this embodiment, the material of the upper and lower electrodes of the model is Pt, with a thickness of 100 nm; the phase change material is Ge1Sb4Te7, with a thickness of 100 nm and a diameter of 250 nm; the insulating layer material is SiO2; the compound electrode material is TiN, and the TiN content in the system is 21%. Randomly select 53 small squares to fill with TiN material, as shown Figure 9 shown (right).

[0078] More specifically, regarding the setting of material parameters, some physical parameters of Ge1Sb4Te7 will also change with the change of temperature. Its electrical conductivity is most sensitive to temperature changes and has the greatest impact on the structure of thermal simulation. The electrical conductivity of Ge1Sb4Te7 at 298 K is 1.97×10 -6 Ω·m, 8.75×10 at 778 K -6 Ω·m, so the conductivity of Ge1Sb4Te7 is set as a linear function of temperature. The other parameters of Ge1Sb4Te7 change little with temperature and are set as constant parameters. The thermal conductivity is set to 2 W / m·K and the density is 6000 kg / m 3 , and the constant-pressure heat capacity is 202 J / kg·K. The specific parameters of other non-phase change materials are shown in Table 2.

[0079] Table 2 Material parameters

[0080] A voltage pulse with an amplitude of 0.5 V and a pulse width of 50 ns was applied to the two models, and the maximum temperature and current density of the phase change film after the pulse was applied were recorded. As shown in Figure 10 (a) and Figure 10 (c), the maximum temperature of the phase change film in the Ge1Sb4Te7 phase change memory unit can only reach 694 K, and the maximum current density is 1.36×10 11 A / m 2 As can be seen from Figure 10 (b) and Figure 10 (d), the maximum temperature of the phase change film in the phase change memory cell containing TiN embedded nano-heating electrodes can reach 818 K, and the maximum current density is 1.78×10 12 A / m 2 , indicating that when reaching the same melting temperature, the phase change memory unit containing the TiN embedded nano-heating electrode structure requires lower voltage pulse energy. The phase change memory device containing the TiN embedded nano-heating electrode can regulate the local current density of the phase change film in the device during the RESET process, playing the role of an internal heating electrode, thereby improving the heat generation efficiency of the phase change memory device and achieving low power consumption during device operation.

[0081] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A phase change film containing embedded nano heating electrodes, characterized in that: It is a phase change film prepared by co-doping compound electrode materials and phase change materials and then subjecting them to pulse treatment; The bonding ability between the atoms of the compound electrode material is stronger than the bonding ability between the atoms of the compound electrode material and the atoms of the phase change material, and the atoms can spontaneously bond to form an embedded nano-heating electrode under the operation of the pulse treatment.

2. The phase change film according to claim 1, characterized in that The compound electrode material includes one or more of TiC, RuO2, Mo2C and TiN.

3. The phase change film according to claim 1 or 2, characterized in that: The atomic ratio of the compound electrode material in the phase change film is 10% to 40%.

4. The phase change film according to claim 1, characterized in that The phase change material includes one or more of a Sb-Te system phase change material and a Ge-Sb-Te system phase change material.

5. The phase change film according to claim 4, characterized in that: The Sb-Te system phase change material includes one or more of SbTe, Sb2Te, Sb4Te and Sb2Te3; and / or, The Ge-Sb-Te system phase change material includes one or more of Ge2Sb2Te5, Ge1Sb4Te7, Ge1Sb2Te4 and Ge4Sb6Te7.

6. The phase change film according to claim 1, characterized in that The co-doping method includes one or more of magnetron co-sputtering, electron beam evaporation, atomic layer deposition, chemical vapor deposition or electroplating; and / or, The pulse is a voltage pulse.

7. A phase change memory comprising a substrate and at least one phase change memory unit disposed on the substrate, characterized in that: The phase change memory unit comprises a lower electrode, an insulating layer, the phase change film according to any one of claims 1 to 6, and an upper electrode; The lower electrode is located on the lower surface of the phase change film; the upper electrode is located on the upper surface of the insulating layer of the phase change film; and the insulating layer is located around the phase change film.

8. The phase change memory according to claim 7, wherein: The phase change film has a restricted structure or a mushroom structure.

9. The phase change memory according to claim 7, wherein: The material of the lower electrode and the upper electrode are independently one or more of Pt, Ti, TiN, W, Au, Ag, Al and Cu; and / or, The insulating layer is made of SiO2, Al2O3, AlN, Si3N4 or BN.

10. The phase change memory according to claim 7, wherein: The thickness of the lower electrode and the upper electrode are independently 10 nm to 400 nm; and / or, The thickness of the insulating layer is 2 nm to 400 nm; and / or, The thickness of the phase change film is 2nm~400nm.

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