Nitrogen pole type ferroelectric nitride multi-valued storage capacitor and preparation method thereof

Abstract

The invention discloses a nitrogen pole type ferroelectric nitride multi-valued storage capacitor which mainly solves the problems that an existing ferroelectric storage capacitor is poor in reliability, low in storage efficiency, low in storage density and difficult to be compatible with a CMOS process. The device comprises a substrate, a buffer layer and a contact layer from bottom to top. A ferroelectric material layer is arranged in the middle above the contact layer, and the half side of the ferroelectric material layer is etched to form a table surface so as to realize output of different storage states; first electrodes are arranged on the two sides of the upper portion of the contact layer so as to control the change of the storage state of the ferroelectric material layer. And a top electrode contact layer and a second electrode which are grown in situ are arranged above the ferroelectric material layer so as to realize the transmission of a storage state and the output of storage data. According to the invention, multi-valued logic storage is realized by using asynchronous change of polarization states of ferroelectric material layers with different thicknesses; the stability, the storage efficiency and the process compatibility of the ferroelectric memory are improved by utilizing the single crystal nitride ferroelectric material with high remanent polarization, high Curie temperature and high breakdown voltage, and the ferroelectric memory can be used for a digital storage circuit.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and particularly relates to a nitrogen-polarized ferroelectric nitride multi-value storage capacitor, which can be used in digital storage circuits in the fields of consumer electronics, industrial Internet of Things, edge computing, and autonomous driving. Background Art

[0002] High-density integrated non-volatile memories have wide applications in the next-generation consumer electronics, industrial Internet of Things, edge computing, and autonomous driving fields. As a kind of non-volatile memory, ferroelectric memories have the advantages of fast read and write speeds, low power consumption, and strong radiation resistance, and have important application prospects in the field of high-performance non-volatile storage in complex environments. As the core component of ferroelectric memories, ferroelectric storage capacitors utilize the characteristic that the polarization state of ferroelectric materials is controllable by an external electric field to achieve data storage and reading. Currently, oxide ferroelectric materials such as barium strontium titanate, barium titanate, doped hafnium oxide, and lead zirconate titanate are mainly used to fabricate ferroelectric memories. The polarization of oxide ferroelectrics is weak, the Curie temperature is low, and the ferroelectric properties depend on oxygen vacancies, resulting in poor high-temperature stability, poor device reliability, and capacitance performance degradation, leading to easy failure of ferroelectric storage units and inability to meet the requirements of frequent read and write of data in complex scenarios. Currently, the stability and reliability of storage units are improved by optimizing the crystal structure and interface properties of thin films, developing new polarization control methods, and optimizing control algorithms.

[0003] The existing ferroelectric storage capacitor structure, such as Figure 1 shown, includes a metal electrode, a ferroelectric material layer, and a metal electrode from bottom to top. This structure needs to be connected in series with an interconnection line and a switching device. Due to the serious contamination of the oxide ferroelectric material deposition process, it is difficult to be compatible with the CMOS process and cannot achieve high-density and large-scale integration. During the read and write process, this capacitor can only perform single-state storage and cannot perform high-density and high-efficiency storage.

[0004] The patent document with the application number CN202410573636.9 discloses a ferroelectric capacitor and its preparation method. Its structure includes an electrode base and a first upper electrode. A first ferroelectric thin film is provided on the outer wall and bottom of the first upper electrode, and a lower electrode is provided on the outer wall and bottom of the first ferroelectric thin film; a second upper electrode; the second upper electrode includes a first sub-structure and a second sub-structure. There is a hollow structure between the adjacent first upper electrodes, and the hollow structure is filled with the first sub-structure of the second upper electrode; the second sub-structure of the second upper electrode is provided on the top of the first upper electrode; a continuous second ferroelectric thin film is provided on the outer wall and bottom of the first sub-structure of the second upper electrode and the bottom of the second sub-structure of the second upper electrode. The second ferroelectric thin film is connected to the lower electrode, and a first dielectric layer is provided between the second ferroelectric thin film and the electrode base. This device realizes a higher-density storage unit arrangement by adopting a double-sided capacitor structure. However, this complex capacitor electrode structure increases the process complexity and can only perform single-value logic storage, resulting in low storage efficiency. Summary of the Invention

[0005] The purpose of the present invention is to propose a nitrogen-pole ferroelectric nitride multi-value storage capacitor and its preparation method for the deficiencies of the above-mentioned existing technologies, so as to improve the device reliability, storage density and storage efficiency, and reduce the process complexity.

[0006] The technical solution of the present invention is realized as follows:

[0007] 1. A nitrogen-pole ferroelectric nitride multi-value storage capacitor, including a substrate, a buffer layer and a contact layer, characterized in that:

[0008] In the middle part above the contact layer, a ferroelectric material layer is provided. Half of this material layer is etched into a mesa to realize different storage states output under different voltages; on both sides above it, a first electrode is provided to control the change of the storage state of the ferroelectric material layer;

[0009] Above the ferroelectric material layer, an in-situ grown top electrode contact layer is provided to realize the transmission of the storage state of the ferroelectric material layer;

[0010] Above the top electrode contact layer, a second electrode is provided to realize the output of the stored data.

[0011] Furthermore, the ferroelectric material layer adopts any one of nitride ferroelectric materials such as ScAlN, YAlN, and BAlN, and its thickness is 5nm - 100nm.

[0012] Furthermore, the top electrode contact layer adopts a thickness of 10nm - 1μm and a doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 of n +GaN material.

[0013] Furthermore, for the mesa etched on one side of the ferroelectric material layer, the etching thickness is half of the thickness of the ferroelectric material layer.

[0014] Furthermore, the buffer layer is located above the substrate, made of nitrogen-polar GaN material, and has a thickness of 50 nm - 10 μm.

[0015] Furthermore, the contact layer is located above the buffer layer, made of n-GaN material with a thickness of 10 nm - 1 μm and a doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 of n + GaN material.

[0016] Furthermore, the substrate is made of any one of GaN, SiC, or Si materials.

[0017] Furthermore, the electrodes are made of any one or any combination of Ni, Ti, Pt, Pd, Al, Cr, Mo, Au, W.

[0018] 2. A manufacturing method of a nitrogen-polar ferroelectric nitride multi-value storage capacitor, characterized by comprising the following steps:

[0019] 1) On the upper part of the substrate, deposit nitrogen-polar GaN with a thickness of 50 nm - 10 μm as the buffer layer by metalorganic chemical vapor deposition technology or molecular beam epitaxy technology;

[0020] 2) By metalorganic chemical vapor deposition technology or molecular beam epitaxy technology, grow an n-GaN with a thickness of 10 nm - 1 μm and a doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 as the contact layer on the buffer layer; + GaN

[0021] 3) By metalorganic chemical vapor deposition technology or molecular beam epitaxy technology, grow a ferroelectric material layer with a thickness of 5 nm - 100 nm on the contact layer, and use etching technology to etch half of one side of the ferroelectric material layer to form a mesa;

[0022] 4) By metalorganic chemical vapor deposition technology or molecular beam epitaxy technology, grow an n-GaN with a thickness of 10 nm - 1 μm and a doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 as the +GaN is used as the top electrode contact layer, and the ferroelectric material layer is etched to be flat by dry etching technology;

[0023] 5) A mask is fabricated on the top electrode contact layer using photolithography technology, and a circular mesa is etched above the contact layer using dry etching technology;

[0024] 6) An electrode pattern is formed using photolithography technology, metal is deposited thereon using electron beam evaporation technology, and annealing is performed in a nitrogen atmosphere to form the first electrode and the second electrode, completing the device fabrication.

[0025] The present invention has the following advantages compared with the prior art:

[0026] 1. Since one side of the ferroelectric material layer is etched into a mesa in the present invention, when the polarization direction of the ferroelectric material is changed by an external electric field, the non-synchronous change characteristic of the polarization state will appear due to the difference in material thickness, and multi-value logic storage can be performed and integrated into a high-density and high-efficiency storage unit.

[0027] 2. Since an in-situ grown top electrode contact layer is provided above the ferroelectric material layer in the present invention, there is no need for interconnections for signal transmission, which improves the storage density, reduces the communication time of discrete components, speeds up the read / write speed of the storage device, and improves the storage efficiency.

[0028] 3. The present invention uses a single-crystal nitride ferroelectric semiconductor with a neat lattice arrangement, high crystal quality, high ferroelectric performance and reliability to replace the oxide semiconductor as the storage layer. The characteristics of high remanent polarization, high Curie temperature, high coercive force field, and high breakdown voltage of the single-crystal nitride ferroelectric semiconductor material can be utilized to improve the stability and reliability of the device. Moreover, the nitride ferroelectric semiconductor material is convenient for integration with existing Si-based semiconductor devices using CMOS technology. Description of the Drawings

[0029] Figure 1 is a schematic structural diagram of an existing ferroelectric storage capacitor;

[0030] Figure 2 is a schematic structural diagram of the nitrogen-pole ferroelectric nitride multi-value storage capacitor of the present invention;

[0031] Figure 3 is a schematic implementation flowchart of fabricating the nitrogen-pole ferroelectric nitride multi-value storage capacitor of the present invention. Detailed Embodiments

[0032] The following further describes the embodiments of the present invention in detail with reference to the drawings:

[0033] Refer to Figure 2, the nitride ferroelectric memory of the present invention includes a substrate 1, a buffer layer 2, a contact layer 3, a ferroelectric material layer 4, a top electrode contact layer 5, a first electrode 6 and a second electrode 7, wherein:

[0034] The substrate 1 is made of any one of GaN, SiC or Si materials;

[0035] The buffer layer 2 is located above the substrate 1 and is made of a nitrogen-polar GaN material with a thickness of 50 nm - 10 μm;

[0036] The contact layer 3 is located above the buffer layer 2 and is made of an n-GaN material with a thickness of 10 nm - 1 μm and a doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 of n + GaN material;

[0037] The ferroelectric material layer 4 is located above the middle part of the contact layer 3 and is made of any one of nitride ferroelectric materials such as ScAlN, YAlN, and BAlN. Its thickness is 5 nm - 100 nm. Half of the ferroelectric material layer 4 is etched into a mesa to achieve different storage states at different voltages and complete multi-state storage;

[0038] The top electrode contact layer 5 is located above the ferroelectric material layer 4 and is made of an n-GaN material with a thickness of 10 nm - 1 μm and a doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 of n + GaN material. The top electrode contact layer 5 is grown in-situ above the ferroelectric material layer 4 to output the storage state of the ferroelectric material layer 4;

[0039] The first electrode 6 is located on both sides above the contact layer 3 and is made of any one or any combination of Ni, Ti, Pt, Pd, Al, Cr, Mo, Au, W. By controlling the voltage of the first electrode 6, the change of the capacitance storage state can be achieved.

[0040] The second electrode 7 is located above the top electrode contact layer 5 and is made of any one or any combination of Ni, Ti, Pt, Pd, Al, Cr, Mo, Au, W.

[0041] Referring to Figure 3 , the present invention provides the following three embodiments for fabricating a nitrogen-polar ferroelectric nitride multi-value storage capacitor.

[0042] Example 1: A nitride ferroelectric multi - value storage capacitor with a ferroelectric material layer made of BAlN with a thickness of 100 nm, a buffer layer with a thickness of 10 μm, contact layers and top - electrode contact layers both with a thickness of 1 μm and doping concentrations of 5×10 20 cm -3 , and the electrode metal material being Ti / Al / Ni / Au.

[0043] Step A: Deposit a nitride - polar GaN buffer layer, as shown in Figure 3 (a).

[0044] Place the Si substrate into a metal - organic chemical vapor deposition (MOCVD) equipment. Using the MOCVD technique, deposit a nitride - polar GaN with a thickness of 10 μm as the buffer layer 2 on the Si substrate 1 under the conditions of a temperature of 1300 °C, a pressure of 60 Torr, an ammonia flow rate of 5000 sccm, a hydrogen flow rate of 3500 sccm, and a gallium source flow rate of 200 sccm.

[0045] Step B: Deposit the contact layer, as shown in Figure 3 (b).

[0046] Using the MOCVD technique, deposit a GaN with a thickness of 1 μm and a doping concentration of 5×10 20 cm -3 as the contact layer 3 on the buffer layer 2 under the conditions of a temperature of 1100 °C, a pressure of 180 Torr, an ammonia flow rate of 5000 sccm, a hydrogen flow rate of 3500 sccm, a gallium source flow rate of 100 sccm, and a silicon source flow rate of 100 sccm.

[0047] Step C: Deposit the ferroelectric material layer, as shown in Figure 3 (c).

[0048] C1) Using the MOCVD technique, deposit a 100 - nm - thick BAlN on the contact layer 3 under the conditions of a temperature of 1100 °C, a pressure of 180 Torr, an ammonia flow rate of 5000 sccm, a hydrogen flow rate of 3500 sccm, an aluminum source flow rate of 4 sccm, and a boron source flow rate of 4000 sccm;

[0049] C2) Using the dry - etching technique, etch 50 nm of the epitaxially grown BAlN on one side to form a mesa as the ferroelectric material layer 4 under the conditions of a Cl2 flow rate of 25 sccm, a reaction - chamber pressure of 15 mTorr, and an electrode power of 220 W.

[0050] Step D: Deposit the top - electrode contact layer, as shown in Figure 3 (d).

[0051] D1) Using metalorganic chemical vapor deposition technology, deposit GaN with a thickness of 1 μm and a doping concentration of 5×10 20 cm -3 on the buffer layer 2 under the conditions of a temperature of 1100 °C, a pressure of 180 Torr, an ammonia flow rate of 5000 sccm, a hydrogen flow rate of 3500 sccm, a gallium source flow rate of 100 sccm, and a silicon source flow rate of 100 sccm as the contact layer 3;

[0052] D2) Using dry etching technology, etch the surface of the epitaxially grown n + GaN material flat under the conditions of a Cl2 flow rate of 28 sccm, a reaction chamber pressure of 16 mTorr, and an electrode power of 240 W as the top electrode contact layer 5.

[0053] Step E, fabricate the electrode pattern, as shown in Figure 3 (e).

[0054] E1) Use photolithography technology to fabricate a mask on the top electrode contact layer 5;

[0055] E2) Use dry etching technology to etch both sides of the top electrode contact layer 5 and the ferroelectric material layer 4 to the surface of the contact layer 3 to form a circular mesa under the conditions of a Cl2 flow rate of 25 sccm, a reaction chamber pressure of 20 mTorr, and an electrode power of 220 W.

[0056] Step F, fabricate the electrodes, as shown in Figure 3 (f).

[0057] F1) Use photolithography technology to fabricate a mask above the contact layer 3 and the top electrode contact layer 5 to form an electrode window;

[0058] F2) Use electron beam evaporation technology to deposit a Ti / Al / Ni / Au metal with a thickness of 50 / 150 / 60 / 40 nm as the first electrode 6 and the second electrode 7 in the anode window under the conditions of a vacuum degree less than 1.2×10 -3 Pa, a power of 500 W, and an evaporation rate of ;

[0059] F3) Perform rapid annealing on the electrode metal in a nitrogen atmosphere at 1200 °C for 30 s to form an ohmic contact and complete the device fabrication.

[0060] Example 2, fabricate a nitride-based ferroelectric multivalued storage capacitor with a ferroelectric material layer thickness of 50 nm, a material of YAlN, a buffer layer thickness of 5 μm, contact layer and top electrode contact layer thicknesses of 500 nm each, and doping concentrations of 1×10 20 cm -3 , and the electrode metal material is Ti / Au.

[0061] Step 1: Use molecular beam epitaxy to grow a nitrogen-polar GaN buffer layer on a SiC substrate, as shown in Figure 3 (a).

[0062] Place the SiC substrate in a molecular beam epitaxy apparatus, and set the temperature to 750 °C, the nitrogen flow rate to 3.2 sccm, the equilibrium vapor pressure of the gallium beam current to 9.5×10 -7 Torr, and the power of the nitrogen radio frequency source to 380 W. Grow a 5-μm-thick nitrogen-polar GaN as buffer layer 2 on SiC substrate 1.

[0063] Step 2: Use molecular beam epitaxy to grow a contact layer, as shown in Figure 3 (b).

[0064] Set the temperature to 550 °C, the nitrogen flow rate to 0.6 sccm, the equilibrium vapor pressure of the gallium beam current to 3.2×10 -7 Torr, and the power of the nitrogen radio frequency source to 250 W. Grow an n 20 cm -3 -type GaN with a thickness of 500 nm and a doping concentration of 1×10 + as contact layer 3.

[0065] Step 3: Use molecular beam epitaxy and dry etching techniques to fabricate a ferroelectric material layer, as shown in Figure 3 (c).

[0066] Set the temperature to 600 °C, the nitrogen flow rate to 0.6 sccm, the equilibrium vapor pressure of the aluminum beam current to 0.6×10 -7 Torr, the equilibrium vapor pressure of the yttrium beam current to 1.8×10 -8 Torr, and the power of the nitrogen radio frequency source to 320 W. On contact layer 3, grow a 50-nm-thick YAlN;

[0067] Set the Cl2 flow rate to 20 sccm, the pressure in the reaction chamber to 12 mTorr, and the electrode power to 200 W. Etch half of the epitaxially grown YAlN by 25 nm to form a mesa as ferroelectric material layer 4.

[0068] Step 4: Use molecular beam epitaxy to grow a top electrode contact layer, as shown in Figure 3 (d).

[0069] Set the temperature to 550 °C, the nitrogen flow rate to 0.6 sccm, the equilibrium vapor pressure of the gallium beam current to 3.2×10 -7 Torr, and the power of the nitrogen radio frequency source to 250 W. On ferroelectric material layer 4, grow an n 20 cm-3 n of + GaN;

[0070] Set the Cl2 flow rate to 20 sccm, the reaction chamber pressure to 15 mTorr, and the electrode power to 220 W. Etch the surface of the epitaxially grown n + GaN flat to serve as the top electrode contact layer 5.

[0071] Step 5, use photolithography technology and reactive ion etching technology to fabricate the electrode pattern, as shown in Figure 3 (e).

[0072] Use photolithography to fabricate a mask on the top electrode contact layer 5. Set the process conditions of Cl2 flow rate to 15 sccm, reaction chamber pressure to 15 mTorr, and electrode power to 200 W. Etch both sides of the top electrode contact layer 5 and the ferroelectric material layer 4 to the surface of the contact layer 3 to form a circular mesa.

[0073] Step 6, use photolithography technology and electron beam evaporation technology to fabricate the electrodes, as shown in Figure 3 (f).

[0074] Use photolithography to fabricate a mask on the contact layer 2 and the top electrode contact layer 5 to form electrode windows;

[0075] Use electron beam evaporation process under the process conditions of vacuum degree less than 1.2×10 -3 Pa, power of 600 W, and evaporation rate of Deposit Ti / Au metal with a thickness of 50 / 90 nm as the first electrode 6 and the second electrode 7 in the anode window;

[0076] Set the temperature to 1100 °C and anneal the cathode metal in a nitrogen atmosphere for 30 s to form an ohmic contact, completing the device fabrication.

[0077] Example 3, fabricate a nitride-based ferroelectric multivalued storage capacitor with a ferroelectric material layer thickness of 5 nm, a material of ScAlN, a buffer layer thickness of 50 nm, contact layer and top electrode contact layer thicknesses of 10 nm each, and doping concentrations of 1×10 19 cm -3 , and an electrode metal material of Ti.

[0078] Step 1, deposit the buffer layer, as shown in Figure 3 (a).

[0079] Place the GaN substrate into a metalorganic chemical vapor deposition equipment and deposit 50 nm thick nitrogen-polar GaN as the buffer layer 2 on the GaN substrate 1 using metalorganic chemical vapor deposition technology;

[0080] Deposition process conditions: temperature is 1000 °C, pressure is 40 Torr, ammonia flow rate is 5000 sccm, hydrogen flow rate is 3500 sccm, and gallium source flow rate is 200 sccm.

[0081] Step 2, deposit the contact layer, as Figure 3 (b).

[0082] Use metalorganic chemical vapor deposition technology to deposit GaN with a thickness of 10 nm and a doping concentration of 1×10 19 cm -3 as the contact layer 3;

[0083] Deposition process conditions: temperature is 1000 °C, pressure is 200 Torr, ammonia flow rate is 5000 sccm, hydrogen flow rate is 3500 sccm, gallium source flow rate is 50 sccm, and silicon source flow rate is 20 sccm.

[0084] Step 3, deposit and etch the ferroelectric material layer, as Figure 3 (c).

[0085] 3.1) Use metalorganic chemical vapor deposition technology to deposit 5-nm-thick ScAlN on the contact layer 3;

[0086] 3.2) Use dry etching to etch half of the ferroelectric material layer 4 by 2.5 nm to form a mesa as the ferroelectric material layer 4;

[0087] Deposition process conditions for ScAlN: temperature is 1000 °C, pressure is 200 Torr, ammonia flow rate is 5000 sccm, hydrogen flow rate is 3500 sccm, aluminum source flow rate is 50 sccm, and scandium source flow rate is 5000 sccm;

[0088] Etching process conditions: Cl2 flow rate is 18 sccm, reaction chamber pressure is 10 mTorr, and electrode power is 160 W.

[0089] Step 4, deposit and etch the top electrode contact layer, as Figure 3 (d).

[0090] 4.1) Use metalorganic chemical vapor deposition technology to deposit n-type GaN with a thickness of 10 nm and a doping concentration of 1×10 19 cm -3 on the ferroelectric material layer 4; + GaN;

[0091] 4.2) Use dry etching to etch the surface of the epitaxially grown n-type GaN material flat to form the top electrode contact layer 5; + GaN material surface etched flat as the top electrode contact layer 5;

[0092] Deposit n+ Process conditions for GaN: temperature is 1000 °C, pressure is 200 Torr, ammonia flow rate is 5000 sccm, hydrogen flow rate is 3500 sccm, gallium source flow rate is 50 sccm, and silicon source flow rate is 20 sccm;

[0093] Process conditions for etching: Cl2 flow rate is 12 sccm, reaction chamber pressure is 10 mTorr, and electrode power is 160 W.

[0094] Step Five, fabricate the electrode pattern, as shown in Figure 3 (e).

[0095] Use photolithography technology to define the mesa pattern on the top electrode contact layer 5, and use dry etching technology to etch the top electrode contact layer 5 and the ferroelectric material layer 4 to the surface of the contact layer 3;

[0096] Process conditions for etching: Cl2 flow rate is 15 sccm, reaction chamber pressure is 15 mTorr, and electrode power is 220 W.

[0097] Step Six, form electrodes on the contact layer and the top electrode contact layer, as shown in Figure 3 (f).

[0098] 6.1) Use photolithography technology to generate the electrode pattern, and use electron beam evaporation process to deposit Ti with a thickness of 100 nm on the contact layer 3 and the top electrode contact layer 5 to form the first electrode 6 and the second electrode 7 respectively. The process conditions for electron beam evaporation are: vacuum degree is less than 1.2×10 -3 Pa, power is 300 W, and evaporation rate is

[0099] 6.2) Use the annealing technology to anneal for 5 min in a nitrogen atmosphere at a temperature of 800 °C to form ohmic contacts and complete the device fabrication.

[0100] The above description is only three specific examples of the present invention and does not constitute any limitation to the present invention. Obviously, for professionals in the field, after understanding the content and principle of the present invention, various modifications and changes in form and details may be made without departing from the principle and structure of the present invention. For example, in addition to the materials used above for the ferroelectric material layer, other nitride ferroelectric materials can also be used; in addition to the metals used above for the electrode metal material, any one or any combination of Ni, Ti, Pt, Pd, Al, Cr, Mo, Au, W can also be used. However, these corrections and changes based on the idea of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A nitrogen-polar ferroelectric nitride multi-value storage capacitor, comprising a substrate (1), a buffer layer (2) and a contact layer (3), characterized in that: For the contact layer (3), a ferroelectric material layer (4) is provided in the middle part above it, and half of the material layer is etched into a mesa to achieve different storage states output under different voltages; first electrodes (6) are provided on both sides above it to control the change of the storage state of the ferroelectric material layer; An in-situ grown top electrode contact layer (5) is provided above the ferroelectric material layer (4) to achieve the transmission of the storage state of the ferroelectric material layer; A second electrode (7) is provided above the top electrode contact layer (5) to achieve the output of stored data.

2. The nitrogen-polar ferroelectric nitride multi-value storage capacitor according to claim 1, characterized in that: The ferroelectric material layer (4) adopts any one of nitride ferroelectric materials such as ScAlN, YAlN, and BAlN, and its thickness is 5 nm - 100 nm; The top electrode contact layer (5) is made of n-GaN material with a thickness of 10 nm - 1 μm and a doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 + .​ 3. The nitrogen-pole ferroelectric nitride multi-value storage capacitor according to claim 1, wherein: For the mesa etched on one side of the ferroelectric material layer (4), the etching thickness is half of the thickness of the ferroelectric material layer (4).

4. The nitrogen-polar ferroelectric nitride multi-value storage capacitor according to claim 1, characterized in that: The buffer layer (2) is located above the substrate (1), and it adopts nitrogen-polar GaN material, and its thickness is 50 nm - 10 μm; The contact layer (3), which is located above the buffer layer (2), is made of an n-GaN material with a thickness of 10 nm - 1 μm and a doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 - + .

5. The nitrogen-polar ferroelectric nitride multi-value storage capacitor according to claim 1, characterized in that: The substrate (1) adopts any one of GaN, SiC, or Si materials; The first electrode (6) and the second electrode (7) adopt any one or any combination of Ni, Ti, Pt, Pd, Al, Cr, Mo, Au, and W.

6. A method for fabricating a nitrogen-polar ferroelectric nitride multi-value storage capacitor, characterized in that, Including the following steps: 1) On the upper part of the substrate (1), deposit nitrogen-polar GaN with a thickness of 50 nm - 10 μm as the buffer layer (2) by metalorganic chemical vapor deposition technology or molecular beam epitaxy technology; 2) Using metalorganic chemical vapor deposition technology or molecular beam epitaxy technology, grow an n-GaN with a thickness of 10 nm - 1 μm and a doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 as the contact layer (3); + ​ 3) By metalorganic chemical vapor deposition technology or molecular beam epitaxy technology, grow a ferroelectric material layer (4) with a thickness of 5 nm - 100 nm on the contact layer (3), and use etching technology to etch half of one side of the ferroelectric material layer (4) to form a mesa; 4) using metal organic chemical vapor deposition technology or molecular beam epitaxy technology to grow a ferroelectric material layer (4) with a thickness of 10 nm to 1 μm and a doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 n + GaN is used as a top electrode contact layer (5), and a ferroelectric material layer (4) is etched to be flat using a dry etching technique; 5) Use photolithography technology to make a mask on the top electrode contact layer (5), and use dry etching technology to etch a circular mesa above the contact layer (3); 6) Use photolithography technology to form an electrode pattern, deposit metal on it by electron beam evaporation technology, and anneal in a nitrogen atmosphere to form the first electrode (6) and the second electrode (7) to complete the device fabrication.

7. The method according to claim 6, wherein: For the metalorganic chemical vapor deposition method in steps 1) - 4), the process conditions are as follows: The temperature is 1000 °C - 1300 °C; the pressure is 40 Torr - 200 Torr; The ammonia flow rate is 5000 sccm; the hydrogen flow rate is 3500 sccm; The aluminum source flow rate is 4 sccm - 50 sccm; the gallium source flow rate is 50 sccm - 200 sccm; The silicon source flow rate is 20 sccm - 100 sccm; the scandium source flow rate is 2000 sccm - 5000 sccm; The flow rate of the yttrium source is 1000 sccm - 3000 sccm; the flow rate of the boron source is 1500 sccm - 4000 sccm.

8. The method according to claim 6, wherein: For the molecular beam epitaxy method in steps 1) - 4), the process conditions are as follows: The temperature is 550 °C - 750 °C; the nitrogen flow rate is 0.6 sccm - 3.2 sccm; The equilibrium vapor pressure of the gallium beam is 3.2×10 -7 Torr - 9.5×10 -7 Torr; The equilibrium vapor pressure of the aluminum beam is 0.6×10 -7 Torr - 3.5×10 -7 Torr; The equilibrium vapor pressure of silicon beam is 0.8×10 -9 Torr - 5.4×10 -9 Torr; The equilibrium vapor pressure of the scandium beam is 0.9×10 -8 Torr - 2.8×10 -8 Torr; The equilibrium vapor pressure of the yttrium beam current is 0.6×10 -8 Torr - 1.8×10 -8 Torr; The equilibrium vapor pressure of the boron beam is 0.3×10 -8 Torr - 1.2×10 -8 Torr; The power of the nitrogen radio frequency source is 250 W - 380 W.

9. The method according to claim 6, wherein: For the dry etching method in steps 3) - 5), the process conditions are as follows: The Cl2 flow rate is 12 sccm - 28 sccm; The pressure in the reaction chamber is 10 mTorr - 20 mTorr; The electrode power is 160 W - 240 W.

10. The method according to claim 6, characterized in that: For the electron beam evaporation technique in steps 5) and 6), the process conditions are as follows: The degree of vacuum is less than 1.2×10 -3 Pa; The power is 300 W - 600 W; The evaporation rate is

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