A multilevel stored AlScN thin film based ferroelectric memory and a method of manufacturing the same

Abstract

The application relates to a multilevel storage ferroelectric memory based on AlScN film and a preparation method thereof, which comprises a lower electrode (1), an Al 1‑x Sc x N film layer (2), an Al 1‑y Sc y N film layer (3) and an upper electrode (4), wherein the Al 1‑x Sc x N film layer (2) is located on the lower electrode (1); the Al 1‑y Sc y N film layer (3) is located on the Al 1‑x Sc x N film layer (2), x is not equal to y, and the diameter of the Al 1‑y Sc y N film layer (3) is smaller than that of the Al 1‑ x Sc x N film layer (2); the upper electrode (4) is located on the Al 1‑x Sc x N film layer (2) and the Al 1‑y Sc y N film layer (3). The ferroelectric memory adopts Al 1‑x Sc x N film layers and Al 1‑y Sc y N film layers to form double-layer films, the components of the two-layer films are ensured to be different by controlling the content of Sc elements, that is, x and y, so that the second layer Al 1‑y Sc y N film changes the remanent polarization intensity of the first layer Al 1‑ x Sc x N film, and realizes the intermediate state of multilevel storage.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor storage, and particularly relates to a multilevel storage ferroelectric memory based on an AlScN thin film and a preparation method thereof. BACKGROUND

[0002] With the rapid development of integrated circuits and information technology, higher requirements are put forward for the storage and transmission of information. At present, the mainstream memory on the market is dynamic random access memory (DRAM), static random access memory (SRAM) and flash memory. DRAM and SRAM are typical volatile memories, which cannot save the data stored therein in the case of power failure. Flash memory is a non-volatile memory, which can still keep data after power failure, but its durability is not ideal, and it requires a high operating voltage. Moreover, with the continuous reduction of semiconductor feature size, flash memory faces the challenge of leakage and power consumption, which cannot be overcome technically. In order to overcome the problems existing in the above memories, new types of memories such as ferroelectric memory, resistive random access memory, phase change memory and magnetic memory are proposed at present.

[0003] Ferroelectric memory has become a research hotspot for the next generation of non-volatile memory because of its low driving voltage, fast data reading speed and high storage density. Under the action of an external electric field, the ferroelectric domain polarization intensity in the ferroelectric memory will flip, so that the ferroelectric memory realizes stable resistance state conversion, thereby realizing data storage. At present, the most studied ferroelectric memory only has two states of "0" and "1", but with the continuous reduction of semiconductor feature size, relying on increasing the number of integrated devices per unit area cannot meet the storage capacity of the memory, so the development of multilevel storage capacity of single device has become an important method to improve the storage capacity of the memory.

[0004] Traditional lead zirconate titanate (PZT) thin films are widely used in ferroelectric memories because of their low deposition temperature, small leakage current and high dielectric constant. However, this material contains lead element, which is not friendly to human body and environment during preparation, and the PZT thin film and strontium bismuth tantalate (SBT) thin film have poor CMOS process compatibility, which cannot be mass-produced. Therefore, it is necessary to use a ferroelectric material which is compatible with CMOS process, has large remanent polarization intensity and is environmentally friendly to improve the performance of ferroelectric memory. In addition, most of the current ferroelectric memories use the method of incomplete flipping of electric domains to realize multilevel storage, but because the incomplete flipping of electric domains has instability and the intermediate state has randomness, it is not suitable for the practical application of ferroelectric multilevel memory. SUMMARY

[0005] In order to solve the above problems in the prior art, the application provides a multilevel storage ferroelectric memory based on an AlScN film and a preparation method thereof.

[0006] The application provides a multilevel storage ferroelectric memory based on an Al 1-x Sc x N film, comprising a lower electrode, an Al 1-x Sc x N film layer, an Al 1-y Sc y N film layer and an upper electrode, wherein

[0007] the Al 1-x Sc x N film layer is located on the lower electrode;

[0008] the Al 1-y Sc y N film layer is located on the Al 1-x Sc x N film layer, x≠y, and the diameter of the Al 1-y Sc y N film layer is smaller than the diameter of the Al 1-x Sc x N film layer;

[0009] the upper electrode is located on the Al 1-x Sc x N film layer and the Al 1-y Sc y N film layer.

[0010] In one embodiment of the application, the material of the lower electrode comprises Pt or TiN, and the thickness is 10-30 nm.

[0011] In one embodiment of the application, 0.1 1-x Sc x N film layer, and the thickness of the Al 1-x Sc x N film layer is 30-70 nm, and the diameter is 0.5-1.0 mm.

[0012] In one embodiment of the application, 0.1 1-y Sc y N film layer, and the thickness of the Al 1-y Sc y N film layer is 30-70 nm, and the diameter is 0.1-0.4 mm.

[0013] In one embodiment of the present application, the material of the upper electrode comprises TiN, and the thickness is 10-50 nm.

[0014] Another embodiment of the present application provides a multi-level Al 1-x Sc x N thin film ferroelectric memory, comprising the steps of:

[0015] S1, growing an Al 1-x Sc x N thin film layer on the lower electrode by using a magnetron sputtering device;

[0016] S2, growing an Al 1-x Sc x N thin film layer on the Al 1-y Sc y N thin film layer, so that x≠y, and the diameter of the Al 1-y Sc y N thin film layer is smaller than the diameter of the Al 1-x Sc x N thin film layer;

[0017] S3, growing an upper electrode on the Al 1-y Sc y N thin film layer and the Al 1-x Sc x N thin film layer by using a magnetron sputtering device;

[0018] S4, annealing the grown sample.

[0019] In one embodiment of the present application, the material of the lower electrode comprises Pt or TiN, and the thickness is 10-30 nm.

[0020] In one embodiment of the present application, step S1 comprises:

[0021] using an Al 1-x Sc x target in a mixed gas of argon and nitrogen to deposit the Al 1-x Sc x N thin film layer by using a reactive sputtering method, wherein 0.1 1-x Sc x The sputtering power of the Al 1-x Sc x N target is 100-160 W, the chamber pressure is 0.4-0.6 Pa, the purity of argon and nitrogen is 99.99%, the flow ratio of argon and nitrogen is 1.5:1, the sputtering temperature is room temperature, and the sputtering thickness of the Al 1-x Sc x N thin film layer is 30-70 nm, and the diameter is 0.5-1.0 mm.

[0022] In one embodiment of the present application, step S2 comprises:

[0023] The Al 1-y Sc y target is deposited in a mixed gas of argon and nitrogen. 1-y Sc y N thin film layer, wherein 0.1<y<0.46. 1-y Sc y The sputtering power of the Al 1-y Sc y N thin film layer is 100-160 W, the chamber pressure is 0.4-0.6 Pa, the purity of argon and nitrogen is 99.99%, the flow ratio of argon and nitrogen is 1.5:1, and the sputtering temperature is room temperature. 1-x Sc x The sputtering thickness of the Al 1-x Sc x N thin film layer is 30-70 nm, and the diameter is 0.1-0.4 mm.

[0024] In one embodiment of the present application, step S3 comprises:

[0025] The TiN upper electrode is deposited in argon by using a TiN target through a magnetron sputtering method, wherein the sputtering power of the TiN target is 80-140 W, the chamber pressure is 0.6-1.2 Pa, the purity of argon is 99.99%, the argon flow is 15-20 sccm, the sputtering temperature is room temperature, and the sputtering thickness of the TiN upper electrode is 10-50 nm.

[0026] Alternatively, the TiN upper electrode is deposited in a mixed gas of argon and nitrogen by using a titanium metal target with a purity of 99.999% through a reactive sputtering method, wherein the sputtering power of the titanium metal target is 80-140 W, the chamber pressure is 0.6-1.2 Pa, the purity of argon and nitrogen is 99.99%, the argon flow is set to 15-20 sccm, the nitrogen flow is set to 1-1.5 sccm, and the sputtering thickness of the TiN upper electrode is 10-50 nm.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] The multilevel storage ferroelectric memory based on the Al 1-x Sc x N thin film of the present application

[0029] 1. The ferroelectric memory of the present application adopts the Al 1-x Sc x N thin film layer and the Al 1-y Sc y N thin film layer to form a double-layer thin film, the contents of Sc elements, i.e., x and y, are controlled to ensure that the components of the two thin films are different, so that the second layer of Al1-y Sc y N thin film plays to change the first layer Al 1-x Sc x The remanent polarization intensity of the N thin film realizes the intermediate state of multi-level storage, compared with the traditional method of incomplete flipping of ferroelectric domains, the multi-level state realized by the structure is more stable, and the multi-bit storage state is also more fixed.

[0030] 2、The ferroelectric material layer in the ferroelectric memory of the application adopts Al 1-x Sc x N thin film and Al 1-y Sc y N thin film, compared with PZT and SBT materials, Al 1-x Sc x N thin film has good compatibility with the traditional CMOS process, which is conducive to large-scale production; in addition, Al 1-x Sc x N thin film has greater remanent polarization intensity, which means that the storage performance such as storage window and on-off ratio of the ferroelectric memory prepared by Al 1-x Sc x N thin film will be greatly improved.

[0031] 3、When the bottom electrode of the ferroelectric memory of the application adopts Pt metal, the Pt substrate has low resistivity and is not easy to oxidize, and the Al 1-x Sc x N thin film, Al 1-y Sc y N thin film has stable chemical properties under high-temperature heat treatment; the top electrode adopts TiN material, the TiN electrode and Al 1-x Sc x N material, Al 1-y Sc y N thin film are nitrides, have good compatibility, and TiN can induce the ferroelectric properties of Al 1-x Sc x N, Al 1-y Sc y N material, improve the remanent polarization intensity of Al 1-x Sc x N, Al 1-y Sc y N material, greatly improve the storage performance of the ferroelectric memory.

[0032] 4、The preparation method of the application only adopts one annealing process to realize double-layer Al 1-x Sc x N, Al 1-y Sc yThe annealing treatment of the N film and the upper electrode TiN can reduce the cost while improving the performance of the device. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 A multi-level storage based on Al 1-x Sc x A structure diagram of the ferroelectric memory with the N film;

[0034] Figure 2 A multi-level storage based on Al 1-x Sc x A structure section view of the ferroelectric memory with the N film;

[0035] Figure 3 A multi-level storage based on Al 1-x Sc x A two-bit data storage state diagram of the ferroelectric memory with the N film;

[0036] Figures 4a-4d A multi-level storage based on Al 1-x Sc x A process diagram of the preparation method of the ferroelectric memory with the N film. DETAILED DESCRIPTION

[0037] The application will be described in further detail below with specific embodiments, but the embodiments of the application are not limited thereto.

[0038] Embodiment one

[0039] Please refer to Figure 1 and Figure 2 , Figure 1 A multi-level storage based on Al 1-x Sc x A structure diagram of the ferroelectric memory with the N film, Figure 2 A multi-level storage based on Al 1-x Sc x A structure section view of the ferroelectric memory with the N film.

[0040] The ferroelectric memory includes a lower electrode 1, an Al 1-x Sc x N film layer 2, an Al 1-y Sc y N film layer 3 and an upper electrode 4. Among them, the Al 1-x Sc x N film layer 2 is located on the lower electrode 1; the Al 1-y Sc yN thin film layer 3 is located on Al 1-x Sc x N thin film layer 2, x≠y, and Al 1- y Sc y N thin film layer 3 has a diameter smaller than Al 1-x Sc x N thin film layer 2 has a diameter; upper electrode 4 is located on Al 1-x Sc x N thin film layer 2 and Al 1- y Sc y N thin film layer 3.

[0041] Specifically, lower electrode 1, Al 1-x Sc x N thin film layer 2, Al 1-y Sc y N thin film layer 3 are sequentially stacked, a portion of upper electrode 4 is located on Al 1-y Sc y N thin film layer 3, and another portion is located on Al 1-x Sc x N thin film layer 2 and surrounds Al 1-y Sc y N thin film layer 3. Al 1-y Sc y N thin film layer 3 has a diameter smaller than Al 1-x Sc x N thin film layer 2 has a diameter, located on Al 1-y Sc y N thin film layer 3, and the diameter of upper electrode 4 on Al 1-y Sc y N thin film layer 3 has equal diameters.

[0042] In one specific embodiment, the material of lower electrode 1 includes Pt or TiN, and the thickness is 10-30 nm. Al 1-x Sc x N thin film layer 2, 0.1 < x < 0.46, Al 1-x Sc x N thin film layer 2 has a thickness of 30-70 nm and a diameter of 0.5-1.0 mm. Al 1-y Sc y N thin film layer 3, 0.1 < y < 0.46 and x≠y, Al 1-y Sc y N thin film layer 3 has a thickness of 30-70 nm and a diameter of 0.1-0.4 mm. The material of upper electrode 4 includes TiN, and the thickness is 10-50 nm.

[0043] See Figure 3 , Figure 3This invention provides a multi-level storage system based on AI. 1-x Sc x A two-bit data storage state diagram of an N-thickness ferroelectric memory. Figure 3 In the image, the upward arrow in the thin film indicates that the polarization intensity is 0, and the downward arrow indicates that a positive polarization intensity has been generated.

[0044] The aforementioned ferroelectric memory uses bilayer Al with different doping concentrations. 1-x Sc x N layer and Al 1-y Sc y N layers (x≠y), give the second layer Al 1-y Sc y When an electric field is applied to the N thin film, it will affect the first Al layer. 1-x Sc x The ferroelectric hysteresis curve of the N-layer is affected, and the control of the first layer Al is also affected. 1-x Sc x The electric field of the N thin film and the second Al layer 1-y Sc y The electric field of the N-film can be used to achieve multi-level storage. For example... Figure 3 As shown, in the "00" state, both V1 and V2 are 0, and the polarization intensity in both ferroelectric thin films is 0; in the "01" state, V1 = V DD V2 = 0, at this time the first layer Al 1-x Sc x The portion of the N thin film in contact with the upper electrode generates a positive polarization intensity P1, and the second Al layer... 1- y Sc y N thin film and first layer Al 1-x Sc x The polarization intensity of the portion of the N-film not in contact with the upper electrode remains 0; in the "10" state, V1 = -V C This voltage will cause the first layer of Al 1-x Sc x The polarization intensity in the N-film at the contact point with the upper electrode is zero, V2 = V DD The applied electric field acts on the second layer Al 1-y Sc y The N thin film, and the second thin film will affect the first Al layer that is in direct contact with it. 1-x Sc x The hysteresis curve of the N thin film has an effect, thus superimposing a positive polarization intensity P2; in the "11" state, V1 = V DD V2 = V DD This makes the first layer of Al 1-x Sc x N thin film and second layer Al 1-y Sc yThe N film stack generates a positive polarization intensity P3. In this way, 4-bit multi-level storage is realized.

[0045] In the embodiment, the ferroelectric material layer is Al 1-x Sc x N film and Al 1-y Sc y N film, Al 1-x Sc x N, Al 1- y Sc y N is a new type of ferroelectric film material. Compared with PZT and SBT materials, Al 1-x Sc x N film, Al 1-y Sc y N film not only has good compatibility with the traditional CMOS process, which is conducive to large-scale production, but also makes up for the instability of the perovskite material. In addition, compared with HfO2 hafnium oxide material, Al 1-x Sc x N film has a higher residual polarization intensity, which exceeds 150 μC / cm 2 , which greatly improves the storage window of the ferroelectric memory and lays a certain foundation for realizing multi-level storage. Thus, the ferroelectric memory prepared from Al 1-x Sc x N film has greater improvement in storage performance such as storage window and on-off ratio.

[0046] In the embodiment, the ferroelectric memory uses Al 1-x Sc x N film layer and Al 1-y Sc y N film layer to form a double-layer film. By controlling the content of Sc element, i.e., x and y, the composition of the two films is ensured to be different, so that the second layer Al 1-y Sc y N film changes the residual polarization intensity of the first layer Al 1-x Sc x N film, and affects the ferroelectric hysteresis curve of the first layer Al 1-x Sc x N film, realizes the intermediate state of multi-level storage, and compared with the traditional method of incomplete flipping of ferroelectric domains, the multi-level state realized by the structure is more stable, and the multi-bit storage state is also more fixed.

[0047] In the ferroelectric memory of the embodiment, when the bottom electrode uses Pt metal, the Pt substrate has low resistivity and is not easy to oxidize, and the Al 1-x Sc x N film, Al 1-y Sc yThe N film is stable in chemical performance under high-temperature heat treatment; the top electrode uses TiN material, the TiN electrode is compatible with Al 1-x Sc x N material, Al 1-y Sc y The N film is a nitride, has good compatibility, and TiN can induce Al 1-x Sc x N, Al 1-y Sc y N material, improves the ferroelectric performance of Al 1-x Sc x N, Al 1-y Sc y N material, greatly improves the storage performance of the ferroelectric memory.

[0048] Embodiment Two

[0049] On the basis of Embodiment One, the embodiment provides a preparation method of a multi-level storage ferroelectric memory based on Al 1-x Sc x N film, which is used for preparing the ferroelectric memory as in Embodiment One.

[0050] Please refer to Figures 4a-4d , Figures 4a-4d the preparation method of the multi-level storage ferroelectric memory based on Al 1- x Sc x N film provided in the embodiment of the application. The preparation method comprises the following steps:

[0051] S1, using a magnetron sputtering device to grow an Al 1-x Sc x N film layer 2 on a lower electrode 1, as shown in Figure 4a 、 4b .

[0052] In one specific embodiment, the material of the lower electrode 1 comprises Pt or TiN, and the thickness is 10-30 nm.

[0053] When the lower electrode 1 uses Pt, the Pt lower electrode 1 is first cleaned. Specifically, the Pt lower electrode 1 is placed on a cleaning rack, and is sequentially cleaned with deionized water, acetone and alcohol in an ultrasonic cleaning machine for 15-20 minutes. The deionized water is used to clean dust on the surface of the Pt substrate, the acetone is used to clean organic impurities on the surface of the Pt substrate, and the alcohol is used to clean the acetone attached to the surface of the substrate. Finally, the Pt lower electrode 1 is cleaned with deionized water for 5-10 minutes, and then is blown dry by using a nitrogen gun.

[0054] When the lower electrode 1 is made of TiN, the TiN lower electrode 1 is prepared by using a magnetron sputtering device, a magnetron sputtering method or a reactive sputtering method. The magnetron sputtering method for preparing the TiN lower electrode 1 includes: after the Si wafer substrate is cleaned in an ultrasonic cleaner and placed in a special tray for magnetron sputtering, the magnetron sputtering target is replaced by a TiN target, when the vacuum in the magnetron sputtering chamber is pumped to 8*10 -4 Pa, pure argon gas with a purity of 99.99% is introduced, and the argon gas flow is set to 15-20sccm, when the argon gas flow is stable, the power is set to 80-140W, the pressure is set to 1.5-2.0Pa, and after the pressure is stable, the sputtering is started, at this time, it can be observed that the glow discharge appears in the magnetron sputtering chamber. Then the pressure is adjusted to 0.6-1.2Pa, and after 10 minutes of pre-sputtering, the sputtering growth of the 10-50nm thick TiN lower electrode 1 is started. The reactive sputtering method for preparing the TiN lower electrode 1 includes: using a titanium metal target with a purity of 99.999%, depositing the TiN lower electrode 1 in a mixed gas of argon and nitrogen by a reactive sputtering method. Specifically, after the Si wafer substrate is cleaned in an ultrasonic cleaner and placed in a special tray for magnetron sputtering, the magnetron sputtering target is replaced by a titanium metal target, when the vacuum in the magnetron sputtering chamber is pumped to 8*10 -4 Pa, a mixed gas of argon and nitrogen is introduced, the argon gas flow is set to 15-20sccm, the nitrogen gas flow is set to 1-1.5sccm, and after waiting for the argon and nitrogen mixed gas flow to be stable, the power is set to 80-140W, the pressure is set to 1.5-2.0Pa, and after the pressure is stable, the sputtering is started, at this time, it can be observed that the glow discharge appears in the magnetron sputtering chamber. Then the pressure is adjusted to 0.6-1.2Pa, and after 10 minutes of pre-sputtering, the sputtering growth of the 10-50nm thick TiN lower electrode 1 is started.

[0055] Further, by using an Al 1-x Sc x target with 0.1 < x < 0.46, an Al 1-x Sc x N thin film layer 2 is deposited in a mixed gas of argon and nitrogen. Specifically, the obtained lower electrode 1 is fixed to a mask plate with a diameter of 0.5-1.0mm, and then placed in a special tray for magnetron sputtering, and the tray is placed in the magnetron sputtering chamber for standby; the vacuum in the magnetron sputtering chamber is pumped to 8*10 -4Pa, then pass in the mixed gas of argon and nitrogen, ensure the flow ratio of argon and nitrogen is 1.5:1, after waiting for the stable flow of the mixed gas of argon and nitrogen, set the power to 100-160W, set the pressure to 1.5-2.0Pa, after the pressure is stable, start sputtering, at this time, the glow discharge in the magnetron sputtering cavity can be observed. Then at the sputtering temperature of room temperature, adjust the pressure to 0.4-0.6Pa, after pre-sputtering for 15 minutes, start sputtering to grow 30-70nm thick Al 1-x Sc x N film layer 2.

[0056] S2, using a magnetron sputtering device, growing Al 1-x Sc x N film layer 2 on the Al 1-y Sc y N film layer 3, so that x≠y, and Al 1-y Sc y The diameter of the Al 1-x Sc x N film layer 3 is smaller than the diameter of the Al 1-x Sc x N film layer 2, as shown in the figure. Figure 4c

[0057] Specifically, the lower electrode 1 on which the Al 1-y Sc y N film layer 2 is grown is fixed to a mask plate with a diameter of 0.1-0.4mm to ensure that the diameter of the second layer of film is smaller than the diameter of the first layer of film, and then placed in a magnetron sputtering special tray, and the tray is placed in the magnetron sputtering cavity for standby, and the target material in the chamber is replaced with Al 1-y Sc y N film, wherein Al 1-y Sc y The sputtering power of the target material is 100-160W, the chamber pressure is 0.4-0.6Pa, the purity of argon and nitrogen is high-purity gas, the purity of which is 99.99%, and the flow ratio of argon and nitrogen is 1.5:1, and the sputtering temperature is room temperature. The specific operation steps are consistent with the steps of preparing Al 1-x Sc x N film layer 2 in step S1.

[0058] S3, using a magnetron sputtering device, growing an upper electrode 4 on the Al 1-y Sc y N film layer 3 and the Al 1-x Sc x N film layer 2, as shown in the figure. Figure 4d ​​

[0059] Specifically, the growth method of the upper electrode 4 includes a magnetron sputtering method or a reactive sputtering method.

[0060] The magnetron sputtering method includes the following steps: fixing the upper electrode 1 of the Al 1-x Sc x N thin film layer 2, the Al 1-y Sc y thin film layer 3 into a 0.5-1.0 mm mask plate, and then placing it into a magnetron sputtering special tray. The tray is placed into a magnetron sputtering cavity for standby, and at the same time, the target material in the cavity is replaced with a TiN target material to ensure that the TiN electrode can be sputtered to the Al 1-y Sc y thin film layer 3 and the Al 1-y Sc y thin film layer 3 covered by the Al 1-x Sc x thin film layer 2. The vacuum in the magnetron sputtering cavity is pumped to 8*10 -4 Afterwards, high-purity argon gas with a purity of 99.99% is introduced, and the argon gas flow is set to 15-20 sccm. When the argon gas flow is stable, the power is set to 80-140 W, and the pressure is set to 1.5-2.0 Pa. After the pressure is stable, the sputtering is started. At this time, it can be observed that there is glow discharge in the magnetron sputtering cavity. Then, at room temperature, the pressure is adjusted to 0.6-1.2 Pa, and after 10 minutes of pre-sputtering, the sputtering growth of a 10-50 nm thick TiN upper electrode is started.

[0061] The reactive sputtering method includes the following steps: fixing the upper electrode 1 of the Al 1-x Sc x N thin film layer 2, the Al 1-y Sc y thin film layer 3 into a 0.5-1.0 mm mask plate, and then placing it into a magnetron sputtering special tray. The tray is placed into a magnetron sputtering cavity for standby, and at the same time, the target material in the cavity is replaced with a TiN target material to ensure that the TiN electrode can be sputtered to the Al 1-y Sc y thin film layer 3 and the Al 1-y Sc y thin film layer 3 covered by the Al 1-x Sc x thin film layer 2. The vacuum in the magnetron sputtering cavity is pumped to 8*10 -4Next, a mixture of argon and nitrogen gas is introduced, with the argon flow rate set to 15-20 sccm and the nitrogen flow rate to 1-1.5 sccm. Once the argon flow rate stabilizes, the power is set to 80-140 W and the pressure to 1.5-2.0 Pa. After the pressure stabilizes, sputtering is initiated, and glow discharge can be observed in the magnetron sputtering chamber. Then, at room temperature, the pressure is adjusted to 0.6-1.2 Pa, and after 10 minutes of pre-sputtering, sputtering growth of a 10-50 nm thick TiN top electrode begins.

[0062] S4. Anneal the well-grown samples.

[0063] Specifically, the grown material with the lower electrode / Al 1-x Sc x N / Al 1-y Sc y The N / top electrode structure sample was fixed on a quartz boat, which was then placed in a horizontal tube furnace for annealing at 400-600℃ in a nitrogen atmosphere for 30-60 minutes, yielding a multi-stage storage-based Al... 1-x Sc x Ferroelectric memory for N thin films.

[0064] The preparation method in this embodiment achieves double-layer Al using only a single annealing process. 1-x Sc x N, Al 1-y Sc y Annealing of the N-film and the TiN top electrode not only improves device performance but also reduces costs.

[0065] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A multilevel stored ferroelectric memory based on Al 1-x Sc x N thin films, characterized in that, Comprise: Lower electrode (1), Al 1-x Sc x N thin film layer (2), Al 1-y Sc y N thin film layer (3) and upper electrode (4), wherein, The Al 1-x Sc x A N thin film layer (2) is located on the lower electrode (1); The Al 1-y Sc y N thin film layer (3) is located on the Al 1-x Sc x N thin film layer (2), x≠y, and the diameter of the Al 1-y Sc y N thin film layer (3) is less than the diameter of the Al 1-x Sc x N thin film layer (2). The upper electrode (4) is located on the Al 1-x Sc x N thin film layer (2) and the Al 1-y Sc y N thin film layer (3).

2. The multi-level stored Al 1-x Sc x N thin film memory of claim 1, wherein, The material of the lower electrode (1) comprises Pt or TiN, and the thickness is 10-30 nm.

3. The multilevel stored Al 1-x Sc x N thin film memory of claim 1, wherein The Al 1-x Sc x 0.1 < x < 0.46 in the N thin film layer (2), the Al 1-x Sc x The thickness of the N thin film layer (2) is 30-70 nm, and the diameter is 0.5-1.0 mm.

4. The multi-level stored Al-based memory of claim 1 wherein the Al-based memory is a ferroelectric memory. 1-x Sc x N thin film. The Al 1-y Sc y 0.1 < y < 0.46 in the N thin film layer (3), the Al 1-y Sc y The thickness of the N thin film layer (3) is 30-70 nm, and the diameter is 0.1-0.4 mm.

5. The multilevel stored Al 1-x Sc x N thin film ferroelectric memory, characterized by, The material of the upper electrode (4) comprises TiN, and the thickness is 10-50 nm.

6. A multilevel stored Al 1-x Sc x N thin film ferroelectric memory, characterized by, Comprise steps: S1, growing Al thin film layer (2) on the lower electrode (1) by using a magnetron sputtering device 1-x Sc x N thin film layer (2); S2, growing an Al 1-x Sc x N thin film layer (2) on the Al 1-y Sc y N thin film layer (3) such that x≠y, and the Al 1-y Sc y N thin film layer (3) has a diameter less than the Al 1-x Sc x N thin film layer (2); S3, growing an upper electrode (4) on the Al 1-y Sc y N thin film layer (3) and the Al 1-x Sc x N thin film layer (2). S4, annealing the well-grown sample.

7. The multilevel stored Al 1-x Sc x A method of fabricating a ferroelectric memory of a thin film of N, characterized by, The material of the lower electrode (1) comprises Pt or TiN, and the thickness is 10-30 nm.

8. The multilevel stored Al 1-x Sc x A method of fabricating a ferroelectric memory of a thin film of N, characterized by, Step S1 comprises: Al 1-x Sc x target, and depositing the Al 1- x Sc x N thin film layer (2), wherein 0.1 < x < 0.46, the Al 1-x Sc x The sputtering power of the target is 100-160 W, the chamber pressure is 0.4-0.6 Pa, the purity of argon and nitrogen is 99.99%, the flow ratio of argon and nitrogen is 1.5:1, and the sputtering temperature is room temperature, the Al 1-x Sc x The sputtering thickness of the N thin film layer (2) is 30-70 nm, and the diameter is 0.5-1.0 mm.

9. The multilevel stored Al 1-x Sc x N thin film ferroelectric memory according to claim 6, characterized in that, Step S2 comprises: Al 1-y Sc y target, and depositing the Al 1- y Sc y N thin film layer (3), wherein 0.1 < y < 0.46, the Al 1-y Sc y The sputtering power of the target is 100-160 W, the chamber pressure is 0.4-0.6 Pa, the purity of argon and nitrogen is 99.99%, the flow ratio of argon and nitrogen is 1.5:1, the sputtering temperature is room temperature, and the Al 1-y Sc y The sputtering thickness of the N thin film layer (3) is 30-70 nm, and the diameter is 0.1-0.4 mm.

10. The multilevel stored Al-based memory of claim 6. 1-x Sc x A method of fabricating a ferroelectric memory of an AlN thin film, characterized by, The step S3 comprises: The TiN upper electrode (4) is deposited in argon by using a TiN target material by a magnetron sputtering method, wherein the sputtering power of the TiN target material is 80-140 W, the chamber pressure is 0.6-1.2 Pa, the purity of argon is 99.99%, the argon flow rate is 15-20 sccm, the sputtering temperature is room temperature, and the sputtering thickness of the TiN upper electrode is 10-50 nm. Alternatively, the TiN upper electrode (4) is deposited in a mixed gas of argon and nitrogen by using a titanium metal target material with a purity of 99.999% by a reactive sputtering method, wherein the sputtering power of the titanium metal target material is 80-140 W, the chamber pressure is 0.6-1.2 Pa, the purity of argon and nitrogen is 99.99%, the argon flow rate is set to 15-20 sccm, the nitrogen flow rate is set to 1-1.5 sccm, and the sputtering thickness of the TiN upper electrode is 10-50 nm.

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