Ferroelectric device processing method, ferroelectric device and ferroelectric memory

Abstract

The invention discloses a ferroelectric device processing method, a ferroelectric device and a ferroelectric memory, oxygen atoms are controlled to rapidly permeate into a lattice structure of a ferroelectric film under a supercritical condition, oxygen vacancies are effectively filled, deep oxidation repair can be realized in a low-temperature environment, the ferroelectric characteristic of the device is further improved, and the performance of the ferroelectric device is improved. The residual polarization intensity is increased, the durability of the ferroelectric device is effectively improved, the wake-up effect is relieved, and the data retention time is prolonged.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to a method for processing ferroelectric devices, as well as ferroelectric devices and ferroelectric memories. Background Technology

[0002] In existing ferroelectric memories, different lattice structures often coexist in the ferroelectric layer, such as monoclinic, tetragonal, and orthorhombic phases. Since different phases possess different symmetries, domain structures, and polarization characteristics, this multiphase coexistence inevitably affects the polarization performance of the ferroelectric thin film. Studies have shown that a high oxygen vacancy concentration in the ferroelectric layer leads to a higher proportion of tetragonal phase in the crystallized ferroelectric thin film, resulting in antiferroelectric characteristics and a significant reduction in remanent polarization. The performance of the ferroelectric layer directly impacts the performance of the ferroelectric memory; therefore, eliminating these performance defects is a pressing issue that needs to be addressed. Summary of the Invention

[0003] This invention provides a method for processing ferroelectric devices, as well as ferroelectric devices and ferroelectric memory, to solve the problem that the performance of ferroelectric memory is affected by the performance defects of existing ferroelectric devices.

[0004] This invention provides a method for processing ferroelectric devices, the method comprising: Carbon dioxide gas is introduced into a premixing tank, and the premixing tank is controlled to reach a supercritical temperature and a supercritical pressure, wherein the supercritical temperature is higher than the critical temperature of carbon dioxide, the supercritical pressure is higher than the critical pressure of carbon dioxide, and the concentration of carbon dioxide in the carbon dioxide gas is greater than 99.9%. A preset liquid co-solvent is injected into the premixing tank, and the components in the liquid co-solvent are fully mixed under the supercritical temperature and supercritical pressure conditions to form a supercritical carbon dioxide fluid. The co-solvent solution is a solution composed of a lower alcohol and water or hydrogen peroxide. The ferroelectric device to be processed is placed in a reaction vessel and immersed in the supercritical carbon dioxide system at a preset flow rate. The preset reaction time is maintained so that the supercritical carbon dioxide system can repair oxygen defects in the ferroelectric layer, gate oxide layer and channel layer of the ferroelectric device. After the reaction time is reached, the reactor is depressurized and cooled to room temperature to obtain the ferroelectric device after oxygen defect repair.

[0005] Optionally, the co-solvent solution is obtained by mixing a lower alcohol with water or hydrogen peroxide at a preset volume ratio under normal temperature and pressure conditions.

[0006] Optionally, the lower alcohol is an alcohol compound with a carbon chain length of 1 to 4 carbon atoms.

[0007] Optionally, the preset volume ratio is 1:1.

[0008] Optionally, when ferroelectric devices are applied to the gate oxide layer of field-effect transistors, after immersion in the supercritical carbon dioxide system, an interface oxide layer is formed between the gate oxide layer and the channel layer, constituting a composite gate structure.

[0009] Optionally, the reaction time is 10-15 minutes.

[0010] Optionally, the preset flow rate is 0.2 mL / s-10 mL / s.

[0011] Optionally, the supercritical temperature is 35℃-100℃; The supercritical pressure is 7.38 MPa - 24.1 MPa.

[0012] Secondly, the present invention provides a ferroelectric device, which is obtained by processing using any of the above-described processing methods.

[0013] Thirdly, the present invention provides a ferroelectric memory, wherein the ferroelectric memory is provided with the aforementioned ferroelectric device.

[0014] The beneficial effects of this invention are as follows: This invention controls the rapid infiltration of oxygen atoms into the lattice structure of ferroelectric thin films under supercritical conditions, effectively filling oxygen vacancies. This enables deep oxidation repair at low temperatures, thereby improving the ferroelectric properties of the device, increasing the residual polarization intensity, effectively enhancing the durability of the ferroelectric device, mitigating the wake-up effect, and improving data retention time.

[0015] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic flowchart of a method for processing ferroelectric devices provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a method for fabricating ferroelectric devices provided in an embodiment of the present invention; Figure 3 This is a schematic diagram comparing the structure of existing ferroelectric devices with that of the ferroelectric device provided in the embodiments of the present invention; Figure 4 This is a schematic diagram comparing the structure of existing ferroelectric devices with that of the ferroelectric device provided in the embodiments of the present invention; Figure 5 This is a schematic diagram comparing the structure of existing ferroelectric devices with that of the ferroelectric device provided in the embodiments of the present invention; Figure 6 This is a schematic diagram comparing the structure of existing ferroelectric devices with that of the ferroelectric device provided in the embodiments of the present invention; Figure description: 100 First substrate, 101 First electrode, 102 Ferroelectric layer, 103 Second electrode, 201 Second substrate, 202 Shallow trench isolation layer, 203 Channel layer, 204 Gate oxide layer, 205 Gate electrode layer, 206 Interface oxide layer. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of the invention.

[0018] To address the problem that oxygen defects in existing ferroelectric device structures affect the performance of ferroelectric devices and consequently reduce the yield of ferroelectric memory, this invention provides a method for processing ferroelectric devices. (See attached document.) Figure 1 The method includes: S101. Introduce carbon dioxide gas into the premixing tank and control the premixing tank to reach supercritical temperature and supercritical pressure. In this embodiment of the invention, the supercritical temperature is higher than the critical temperature of carbon dioxide, the supercritical pressure is higher than the critical pressure of carbon dioxide, and the concentration of carbon dioxide in the carbon dioxide gas is greater than 99.9%. Specifically, in this embodiment of the invention, the supercritical temperature is 35℃-100℃; and the supercritical pressure is 7.38Mpa-24.1Mpa.

[0019] In specific implementation, the supercritical temperature can be set to 35°C and the supercritical pressure to 7.38 MPa, as long as it can ensure the formation of supercritical carbon dioxide fluid. Those skilled in the art can set the supercritical temperature, supercritical pressure and carbon dioxide concentration as needed, and the present invention does not impose specific limitations on them.

[0020] It should be noted that, between steps S101, the method further includes: mixing the lower alcohol with water or hydrogen peroxide at a preset volume ratio to obtain the co-solvent solution under normal temperature and pressure conditions.

[0021] In this embodiment of the invention, the lower alcohols are alcohol compounds with a carbon chain length of 1 to 4 carbon atoms.

[0022] Furthermore, in the embodiments of the present invention, the preset volume ratio of lower alcohol to water or hydrogen peroxide is 1:1. That is to say, in the embodiments of the present invention, lower alcohol and water are mixed in a 1:1 ratio, or lower alcohol and hydrogen peroxide are mixed in a 1:1 ratio. Of course, water and hydrogen peroxide can also be mixed, and then the mixed water and hydrogen peroxide are mixed with lower alcohol in a 1:1 ratio.

[0023] S102. Inject the preset liquid co-solvent into the premixing tank, and under supercritical temperature and supercritical pressure conditions, fully mix the components in the liquid co-solvent to form a supercritical carbon dioxide fluid. S103. Place the ferroelectric device to be processed in a reaction vessel and immerse it in the supercritical carbon dioxide system at a preset flow rate, maintaining a preset reaction time, so that the supercritical carbon dioxide system repairs the oxygen defects in the ferroelectric layer 102, the gate oxide layer, and the channel layer of the ferroelectric device. By controlling the penetration of oxygen atoms into the lattice structure of ferroelectric thin films under supercritical conditions, oxygen vacancies can be effectively filled, thus achieving deep oxidation repair at low temperatures. This not only enhances the ferroelectric properties of the device and increases the remanent polarization intensity, but also effectively improves the durability of the ferroelectric device, alleviates the wake-up effect, and extends data retention time.

[0024] In other words, this embodiment of the invention uses a supercritical process to crystallize the uncrystallized portion of the ferroelectric layer 102, thereby altering the stress field. This not only optimizes the crystal structure but also effectively increases the remanent polarization intensity and expands the storage window.

[0025] Furthermore, the high diffusivity of the supercritical fluid in this embodiment of the invention allows the co-solvent to penetrate uniformly to the material surface, enabling the ferroelectric thin film to still exhibit a ferroelectric phase when it is less than 3 nm, thereby facilitating the fabrication of highly integrated ultrathin ferroelectric gate oxide transistors.

[0026] In this embodiment of the invention, the reaction time is 10-15 minutes. Of course, in specific implementation, the reaction time is set so as to repair oxygen defects. This invention does not make any specific limitation on this.

[0027] S104. After the reaction time is reached, the reactor is depressurized and cooled to room temperature to obtain the ferroelectric device after oxygen defect repair.

[0028] In simple terms, the embodiments of the present invention involve rapidly and uniformly diffusing supercritical fluid into the lattice structure of a high-dielectric-constant ferroelectric gate oxide layer after the ferroelectric device has been fabricated using a supercritical process. This effectively reduces oxygen vacancies in the ferroelectric material, thereby achieving a hysteresis-free phenomenon in the transistor transfer characteristic curve.

[0029] It should be noted that when the structure of the ferroelectric device is applied to the MOS capacitor in the field-effect transistor, after processing by the method of the present invention, the ferroelectric device is immersed in the supercritical carbon dioxide system, which can form an interface oxide layer between the gate oxide layer and the channel layer. The interface oxide layer and the gate oxide layer constitute a negative capacitance effect, thereby further optimizing the performance of the ferroelectric device on the basis of repairing oxygen defects.

[0030] In specific implementation, the preset flow rate of the immersion in the supercritical carbon dioxide system is controlled to be 0.2-10 mL / s in this embodiment of the invention. Experimental verification shows that when the ferroelectric device is immersed in the supercritical carbon dioxide system at a flow rate of 0.2-10 mL / s, oxygen defects in the ferroelectric layer, gate oxide layer, and channel layer can be repaired to the greatest extent.

[0031] Practice has proven that the ferroelectric devices processed by the method of this invention can effectively optimize ferroelectric memory, improve the durability of ferroelectric memory, alleviate its wake-up effect, and improve the data retention time and expand the storage window of ferroelectric memory, among other excellent parameter indicators.

[0032] The following will combine Figure 2 and Figure 6 The method described in the embodiments of the present invention will be explained and illustrated in detail through a specific example: This invention first proposes a supercritical treatment process to improve ferroelectric properties, such as... Figure 2 As shown, a first electrode 101, a ferroelectric layer 102, and a second electrode 103 are sequentially formed on a first substrate 100, stacked in order. In this embodiment, the first electrode 101 and the second electrode 103 are electrode layers; however, those skilled in the art can configure them according to actual needs, and this invention does not impose specific limitations on this.

[0033] The processing steps for ferroelectric devices in this embodiment of the invention include the following steps: S1. Clean the first substrate 100; That is, the surface of the first substrate 100 is pre-cleaned to remove particulate impurities, organic contaminants, native oxides, etc.

[0034] In this embodiment, boron-doped single-crystal silicon can be used as the substrate. It is placed in a beaker containing isopropanol, acetone and deionized water for ultrasonic cleaning, then immersed in a diluted hydrogen fluoride solution, and finally dried with high-purity nitrogen gas for later use.

[0035] The substrate can be selected from silicon wafers, germanium wafers, silicon-germanium alloys, silicon on insulators, etc.

[0036] S2. Grow the first electrode 101 on the first substrate 100; The first electrode 101 is located on the top surface of the substrate. In this embodiment, one or more conductive thin films such as titanium, titanium nitride, tungsten, nickel, tantalum, tantalum nitride, ruthenium, and platinum can be deposited on the first substrate 100 prepared in step one by organic chemical vapor deposition, thermal evaporation deposition, ion beam deposition, magnetron sputtering, electroplating, or electron beam evaporation deposition as the first electrode 101. It is worth noting that the first electrode 101 is a single layer, covering the top surface of the first substrate 100 without the need for micro- or nano-fabrication processes to pattern it.

[0037] S3. A ferroelectric layer 102 is grown on the first electrode 101; Specifically, a ferroelectric layer 102 is formed, which is located on the top surface of the bottom electrode layer.

[0038] In this embodiment, the ferroelectric layer 102 can be prepared by methods such as atomic layer deposition, evaporation deposition, ion beam deposition, and magnetron sputtering.

[0039] In this embodiment, the ferroelectric layer 102 may be hafnium zirconium oxide, lead zirconate titanate, lead titanate, barium titanate, or hafnium oxide doped with silicon, strontium, yttrium, germanium, aluminum, or lanthanum.

[0040] To ensure that there is no electrical connection between the first electrode 101 and the second electrode 103, the thickness of the ferroelectric layer 102 ranges from 1 nm to 20 nm.

[0041] S4. A second electrode 103 is grown on the ferroelectric layer 102; In this embodiment, the material of the second electrode can refer to the first electrode 101 described above, and will not be repeated here. It should be noted that this step can be implemented in two ways. First, a conductive thin film material is deposited, followed by a series of micro / nano fabrication processes such as spin-coating photoresist, exposure, baking, development, fixing, etching, and resist removal to pattern the top electrode. Second, a top electrode pattern with voids is first formed by spin-coating photoresist, exposure, and development, followed by the deposition and filling of the conductive thin film material, and finally the photoresist is dissolved.

[0042] In this embodiment of the invention, the first electrode 101 and the second electrode 103 are both conductive thin film materials, such as metallic materials. Specifically, the first electrode 101 and the second electrode 103 can be one or more of titanium, titanium nitride, tungsten, nickel, tantalum, tantalum nitride, ruthenium, and platinum grown by deposition processes such as metal-organic chemical vapor deposition, thermal evaporation deposition, ion beam deposition, magnetron sputtering, electroplating, and electron beam evaporation deposition.

[0043] Furthermore, in this embodiment of the invention, the ferroelectric layer 102 is grown using thin film preparation processes such as plasma-enhanced atomic layer deposition, evaporation deposition, ion beam deposition, and magnetron sputtering to grow thin film materials such as hafnium zirconium oxide, lead zirconate titanate, lead titanate, and barium titanate.

[0044] In specific embodiments of the present invention, the thickness of the ferroelectric thin film material can be 1-20 nm, so as to ensure that a short circuit is not caused by the electrical connection between the first electrode 101 and the second electrode 103 when measuring ferroelectric devices.

[0045] After the ferroelectric thin film is deposited, or after the first electrode 101 is deposited, the ferroelectric layer 102 can be subjected to heat treatment processes such as furnace tube annealing, rapid thermal annealing, laser annealing or heating table annealing to induce the ferroelectric thin film to undergo a non-centrosymmetric crystal phase transformation, thereby obtaining stable ferroelectric properties.

[0046] In specific implementations, the modification of the ferroelectric layer 102 in this embodiment of the invention includes, but is not limited to, the following methods: (1) In order to reduce the problem that the ferroelectric layer 102 cannot obtain a high-quality single crystal structure when grown on the amorphous interface, if the bottom electrode layer, i.e. the second electrode 103, has a native oxide, the native oxide is treated by impregnation with hydrogen fluoride. Ferroelectric thin film materials such as hafnium zirconium oxide, lead zirconate titanate, lead titanate, and barium titanate are grown on the treated bottom electrode layer using thin film preparation processes such as plasma-enhanced atomic layer deposition, evaporation deposition, ion beam deposition, and magnetron sputtering.

[0047] (2) By using magnetron sputtering, atomic layer deposition and other methods, chromium, silicon, strontium, yttrium, germanium, aluminum, lanthanum and other elements are doped into the ferroelectric layer 102, thereby affecting the surface morphology, band gap, crystal phase transformation, dielectric constant, breakdown electric field, coercive electric field and leakage current and other performance parameters of the ferroelectric thin film material.

[0048] S5. Heat treatment process induces ferroelectric phase transition in thin film; The core objective of this step is to induce the thin film to transform into a non-centrosymmetric orthorhombic phase in order to obtain a stable ferroelectric phase. In this embodiment, the target device can be annealed using heat treatment processes such as furnace tube annealing, rapid thermal annealing, laser annealing, or heated stage annealing.

[0049] S6. Post-processing is performed using supercritical treatment technology; In this embodiment, a co-solvent of deionized water and ethanol in a 1:1 volume ratio was first prepared at room temperature and pressure. Then, high-purity carbon dioxide was introduced into a chamber at 36°C, and the chamber pressure was increased to 24.1 MPa using a high-pressure pump, thereby generating supercritical carbon dioxide fluid. Subsequently, the prepared liquid co-solvent was injected into the supercritical carbon dioxide fluid using a high-pressure injection pump. Under the aforementioned supercritical pressure and temperature conditions, the co-solvent and supercritical carbon dioxide were thoroughly mixed to form a homogeneous supercritical carbon dioxide system. The ferroelectric device sample was placed in the reaction chamber, and the reaction time and immersion flow rate were set to 30 min and 0.2 ml / s, respectively. Finally, the pressure was slowly released and the mixture was cooled to room temperature before removing the ferroelectric transistor sample.

[0050] Specifically, S6 in this embodiment of the invention includes: S6a. Prepare a liquid co-solvent solution in advance under normal temperature and pressure conditions; In this embodiment of the invention, the co-solvent solution can be a mixture of a low-level alcohol compound with a carbon chain length between 1 and 4 carbon atoms and water or hydrogen peroxide in a specific volume ratio. The alcohol acts as a medium to combine nonpolar carbon dioxide molecules with polar water molecules or hydrogen peroxide to form a supercritical system optimized for the target device. Furthermore, in this embodiment of the invention, the high-purity carbon dioxide gas should be converted to a supercritical state at an environment above approximately 35°C and above approximately 7.38 MPa.

[0051] S6b. High-purity carbon dioxide gas is introduced into the high-pressure premixing tank and pressurized to a range higher than the critical pressure of carbon dioxide by a high-pressure pump, while adjusting the container temperature to a set value higher than the critical temperature. S6c. The liquid co-solvent is injected into the formed supercritical carbon dioxide fluid using a high-pressure injection pump, and the two are fully mixed under supercritical temperature and pressure conditions to obtain a homogeneous supercritical carbon dioxide system. S6d. Place the ferroelectric device sample to be processed in the reactor and immerse it in the supercritical carbon dioxide system at a preset flow rate. In this embodiment of the invention, the preset flow rate is 0.2 mL / s.

[0052] S6e. While maintaining the supercritical pressure and temperature conditions, maintain the set reaction time, then slowly depressurize and cool to room temperature, and take out the supercritical ferroelectric device sample.

[0053] It should be noted that the focus of this invention is on the post-optimization treatment of ferroelectric transistors using supercritical processes, thereby improving the interface quality and polarization response performance of the ferroelectric gate oxide layer. The invention is characterized in that: after supercritical fluid treatment, the ferroelectric transistor obtains an interface oxide layer 206 between the ferroelectric gate oxide layer and the channel layer 203, thus forming a composite gate structure. In other words, when the ferroelectric device is applied to the gate oxide layer 204 of a field-effect transistor, after immersion in the supercritical carbon dioxide system, an interface oxide layer 206 is formed between the gate oxide layer 205 and the channel layer 203, constituting a composite gate structure.

[0054] Practice has proven that, under supercritical conditions, oxygen atoms in the embodiments of this invention can rapidly penetrate into the crystal structure of the ferroelectric thin film, effectively filling oxygen vacancies and achieving deep oxidation repair at low temperatures. This not only enhances the ferroelectric properties of the device and increases the remanent polarization intensity but also effectively improves the durability of the ferroelectric device, alleviates the wake-up effect, and increases data retention time. Furthermore, the supercritical process allows the uncrystallized portions of the ferroelectric layer 102 to crystallize, altering the stress field. This not only optimizes its crystal structure but also effectively increases the remanent polarization intensity and expands the storage window.

[0055] See Figures 3-4 This embodiment also provides a high-performance ferroelectric transistor with negative capacitance characteristics that has undergone supercritical treatment.

[0056] Ferroelectric gate oxide transistors obtained based on supercritical processing are applied to several different types of transistors, including planar transistors, fin field-effect transistors, gate-around field-effect transistors with a second substrate 201 of single-crystal silicon, and gate-around field-effect transistors with a second substrate 201 of silicon-on-insulator.

[0057] like Figures 3-4 As shown, the left column of devices represents transistors fabricated using conventional processes, while the right column represents high-performance ferroelectric gate oxide transistors with optimized negative capacitance characteristics after supercritical processing. From top to bottom, the rows represent: ferroelectric planar transistors, ferroelectric fin field-effect transistors, ferroelectric gate-around field-effect transistors with a second substrate 201 of single-crystal silicon, and ferroelectric gate-around field-effect transistors with a second substrate 201 of silicon-on-insulator.

[0058] The ferroelectric planar transistor, ferroelectric fin field-effect transistor, and ferroelectric gate-all-around field-effect transistor with a single-crystal silicon substrate optimized by supercritical process are provided with a second substrate 201, a shallow trench isolation layer 202, a channel layer 203, a gate oxide layer 204, a gate electrode layer 205, and an interface oxide layer 206. The silicon-on-insulator ferroelectric gate-all-around field-effect transistor is provided with a second substrate 201, a channel layer 203, a gate oxide layer 204, a gate electrode layer 205, and an interface oxide layer 206. It is worth noting that the focus of this invention is on the post-processing of the transistor by the supercritical process. Except for the interface oxide layer 206, the other structural layers can be formed using existing technologies, which will not be described in detail in this embodiment.

[0059] Supercritical treatment is performed on the gate oxide layer of existing ferroelectric planar transistors, ferroelectric fin field-effect transistors, ferroelectric all-around gate field-effect transistors with single-crystal silicon as the second substrate 201, and all-around gate field-effect transistors with silicon-on-insulator as the second substrate 201 to form an interface gate oxide layer.

[0060] In this embodiment of the invention, the gate oxide layer 204 can be hafnium oxide or hafnium oxide doped with one or more elements selected from zirconium, chromium, silicon, strontium, yttrium, germanium, aluminum, and lanthanum. The channel layer 203 can be undoped single-crystal silicon, doped single-crystal silicon, polycrystalline silicon, amorphous silicon, amorphous hydride, single-crystal germanium, silicon-germanium alloy, or other semiconductor materials. Those skilled in the art can configure the material according to actual needs, and this invention does not impose detailed limitations on these aspects.

[0061] The co-solvent solution in this invention can be a mixture of a low-level alcohol compound with a carbon chain length between 1 and 4 carbon atoms and water or hydrogen peroxide in a specific volume ratio. The alcohol acts as a medium to combine nonpolar carbon dioxide molecules with polar water molecules or hydrogen peroxide to form a supercritical system optimized for the target device.

[0062] In this embodiment, a co-solvent of deionized water and ethanol in a 1:1 volume ratio is first prepared at room temperature and pressure. Then, high-purity carbon dioxide is introduced into a chamber at 36°C, and the chamber pressure is increased to 24.1 MPa using a high-pressure pump, thereby generating supercritical carbon dioxide fluid. The prepared liquid co-solvent is then injected into the supercritical carbon dioxide fluid using a high-pressure injection pump. Under the aforementioned supercritical pressure and temperature conditions, the co-solvent and supercritical carbon dioxide are thoroughly mixed to form a homogeneous supercritical carbon dioxide system. The target ferroelectric transistor sample is placed in the reaction chamber and immersed in the supercritical carbon dioxide system at a fixed flow rate for a sufficient reaction time. Finally, the pressure is slowly released and the mixture is cooled to room temperature before the ferroelectric transistor sample is removed. The transistor obtained by the fabrication method described in this embodiment is as follows: Figures 3-6As shown, an interface oxide layer 206 is obtained between the gate oxide layer and the channel layer 203. It can be understood that this silicon dioxide layer and the ferroelectric layer 102 form a composite gate structure, which enables the field-effect transistor to have negative capacitance characteristics, which can be used to improve switching speed and reduce static power consumption.

[0063] Practice has proven that the method of this invention enables the high diffusivity of supercritical fluids to allow the co-solvent to penetrate uniformly to the material surface, so that ferroelectric thin films can still exhibit the ferroelectric phase when the thickness is less than 3 nm, thereby facilitating the fabrication of highly integrated ultrathin ferroelectric gate oxide transistors.

[0064] After the ferroelectric transistor is fabricated, a supercritical fluid is rapidly and uniformly permeated into the interface between the ferroelectric gate oxide layer and the conductive channel using a supercritical process, forming a dense interface oxide layer 206 in a very short time. It is understood that this interface oxide layer 206 and the ferroelectric layer 102 constitute a composite gate structure, giving the transistor negative capacitance characteristics, which can be used to improve switching speed and reduce static power consumption.

[0065] After fabricating the ferroelectric transistor, a supercritical fluid is rapidly and uniformly diffused into the lattice structure of the high-dielectric-constant ferroelectric gate oxide layer using a supercritical process, effectively reducing oxygen vacancies in the ferroelectric material. This achieves hysteresis-free operation in the transistor's transfer characteristic curve.

[0066] It should be noted that in the embodiments of the present invention, the first electrode 101, the second electrode 103 and the gate electrode layer 205 are conductive layers. Those skilled in the art can make specific settings according to actual conditions, and the present invention will not discuss them in detail.

[0067] Meanwhile, this embodiment of the invention also provides a ferroelectric device, which is obtained by processing using any of the above-described processing methods.

[0068] In addition, this embodiment of the invention also provides a ferroelectric memory, wherein the ferroelectric memory is provided with a ferroelectric device prepared in this embodiment of the invention.

[0069] It should be noted that the ferroelectric devices and ferroelectric memories in the embodiments of the present invention can be understood by referring to the method embodiments of the present invention, and will not be discussed in detail here.

[0070] Although preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will recognize that various modifications, additions, and substitutions are possible, and therefore the scope of the invention should not be limited to the embodiments described above.

Claims

1. A method for processing ferroelectric devices, characterized in that, The method includes: Carbon dioxide gas is introduced into a premixing tank, and the premixing tank is controlled to reach a supercritical temperature and a supercritical pressure, wherein the supercritical temperature is higher than the critical temperature of carbon dioxide, the supercritical pressure is higher than the critical pressure of carbon dioxide, and the concentration of carbon dioxide in the carbon dioxide gas is greater than 99.9%. A preset liquid co-solvent is injected into the premixing tank, and the components in the liquid co-solvent are fully mixed under the supercritical temperature and supercritical pressure conditions to form a supercritical carbon dioxide fluid. The co-solvent solution is a solution composed of a lower alcohol and water or hydrogen peroxide. The ferroelectric device to be processed is placed in a reaction vessel and immersed in the supercritical carbon dioxide system at a preset flow rate. The preset reaction time is maintained so that the supercritical carbon dioxide system can repair oxygen defects in the ferroelectric layer, gate oxide layer and channel layer of the ferroelectric device. After the reaction time is reached, the reactor is depressurized and cooled to room temperature to obtain the ferroelectric device after oxygen defect repair.

2. The processing method according to claim 1, characterized in that, The co-solvent solution is obtained by mixing a lower alcohol with water or hydrogen peroxide at a preset volume ratio under normal temperature and pressure conditions.

3. The processing method according to claim 2, characterized in that, The lower alcohols are alcohol compounds with a carbon chain length of 1 to 4 carbon atoms.

4. The processing method according to claim 2, characterized in that, The preset volume ratio is 1:

1.

5. The processing method according to claim 1, characterized in that, When ferroelectric devices are applied to the gate oxide layer of field-effect transistors, after immersion in the supercritical carbon dioxide system, an interface oxide layer is formed between the gate oxide layer and the channel layer, constituting a composite gate structure.

6. The processing method according to any one of claims 1-5, characterized in that, The reaction time is 10-15 minutes.

7. The processing method according to any one of claims 1-5, characterized in that, The preset flow rate is 0.2 mL / s-10 mL / s.

8. The processing method according to any one of claims 1-5, characterized in that, The supercritical temperature is 35℃-100℃; The supercritical pressure is 7.38 MPa - 24.1 MPa.

9. A ferroelectric device, characterized in that, The ferroelectric device is obtained by processing using any one of claims 1-8.

10. A ferroelectric memory, characterized in that, The ferroelectric memory includes the ferroelectric device as described in claim 9.

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