High dielectric tuning film based on lead zirconate seed layer induced orthorhombic hafnium zirconate and preparation method thereof

Abstract

This invention discloses a high-dielectric tunable thin film based on orthogonal ferroelectric hafnium zirconate induced by a lead zirconate seed layer and its preparation method, mainly solving the problems of long preparation cycle, low breakdown electric field resistance, and low dielectric tunability in existing technologies. From bottom to top, it includes a substrate, a lead zirconate (PZO) layer, and a hafnium zirconate (HZO) layer. The lead zirconate (PZO) layer, with a thickness of 300-500 nm and a composition of PbZrO3, serves as the seed layer, inducing the hafnium zirconate group to form an orthogonal phase, thus giving the thin film ferroelectric properties. The fabrication process involves first spin-coating a PZO precursor sol solution onto a silicon-based, quartz glass-based, or sapphire substrate to obtain a wet PZO film, followed by drying and pyrolysis to obtain the seed layer; then, an HZO-based precursor solution is spin-coated onto the seed layer, followed by drying, pyrolysis, and crystallization annealing to obtain the high-dielectric tunable thin film. This invention enables the low-temperature synthesis of HZO thin films at temperatures ranging from 350°C to 550°C. The process is convenient and efficient, and can be used for the low-cost integration and large-scale fabrication of ferroelectric functional devices.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, and specifically relates to a high-dielectric-tunable thin film and its preparation method, which can be used in miniaturized and highly integrated phase shifters. Background Technology

[0002] Phase shifters are core components of phased array antennas and are widely used in 5G / 6G communications, satellite communications, and radar systems. With the development of radar, satellite, and communication technologies, miniaturized and highly integrated phase shifters will be the development trend for both military and civilian applications. However, traditional semiconductor diode phase shifters and ferrite phase shifters generally suffer from problems such as large size, high power consumption, low integration, difficulty in lightweight design, and incompatibility with silicon-based semiconductor processes, making it difficult to meet the core requirements of radar, satellite, and communication systems for low loss, miniaturization, and low cost.

[0003] To overcome the aforementioned limitations, dielectric phase shifters using barium strontium titanate (BST) thin-film phase shifters have solved the problems of high loss, large size, and heavy weight, but still suffer from issues such as thick films and incompatibility with silicon-based semiconductor processes. Meanwhile, the discovery of novel hafnium zirconate-based materials can perfectly solve the problems of miniaturization and integration, and is compatible with CMOS processes. However, the processing conditions for their ferroelectric thin films are demanding, such as requiring annealing under a nitrogen atmosphere and relying on specific metal electrodes such as TiN and W, leading to complex fabrication, high cost, and challenges related to insufficient repeatability and stability. Therefore, developing a phase shifter material that is versatile, simple to process, easy to integrate, and has excellent performance has become an urgent technological development direction.

[0004] Patent document CN20131015209.2 discloses a composite thin film with high energy storage density and its preparation method. The bottom and top layers of the composite thin film are lead zirconate-based thin film layers; the middle layer is a barium titanate-based binary solid solution thin film layer. The preparation method is to prepare lead zirconate-based precursor solution and barium titanate-based binary solid solution precursor solution respectively by preparing lead zirconate-based precursor solution and barium titanate-based binary solid solution precursor solution. The prepared lead zirconate-based precursor solution is spin-coated onto a Pt(111) / Ti / SiO2 / Si substrate to obtain a wet film. The obtained wet film is then baked, pyrolyzed, and annealed in an oxygen atmosphere to obtain the lead zirconate-based thin film layer. Then, following the above preparation process of the lead zirconate-based thin film layer, the barium titanate-based binary solid solution thin film layer and the lead zirconate-based thin film layer are prepared sequentially on the prepared lead zirconate-based thin film layer. The method employs a sandwich structure of "bottom layer-middle layer-top layer," requiring multiple spin coatings and annealing processes. Each annealing requires precise temperature and atmosphere control, resulting in a long preparation cycle, low efficiency, and the potential for thermal stress from multiple high-temperature treatments to cause film cracking or interfacial diffusion, affecting product yield and hindering large-scale industrial production. Furthermore, this method is limited to using Pt(111) / Ti / SiO2 / Si as the substrate, and the high cost of platinum electrodes restricts the application prospects of the thin film.

[0005] Patent document with application number CN202010979494.8 discloses a method for controlling Pb(Zr) through a substrate. x Ti 1-x A method for preparing Pb(Zr) thin film with high electrical properties, which involves using Pb(Zr) to achieve high electrical properties. x Ti 1-x A wet film was prepared by spin-coating an O3 precursor solution onto a substrate; the product was dried, pyrolyzed, and annealed to obtain a monolayer of Pb(Zr) x Ti 1-x O3 thin film; repeat the previous steps to prepare multilayer Pb(Zr) films. x Ti 1-x O3 thin films. Although this method yields thin films with high purity, good density, small average grain size, high electric field breakdown strength, wide tunable temperature range, and large electrocaloric effect, the main body of the thin film is lead zirconate titanate (PZT), with a lead content exceeding 60 wt%. Therefore, there is a risk of lead volatilization and leakage throughout the entire process of preparation, processing, use, and even disposal. Furthermore, under repeated electric field cycling, the residual polarization intensity of the PZT thin film will decrease significantly, leading to device performance degradation or even failure.

[0006] In summary, while the lead-containing thin-film technologies disclosed in the above patents each emphasize high energy density or high energy efficiency, they fundamentally contradict the core requirements of current phase shifters, which are moving towards miniaturization, high integration, low power consumption, and environmental friendliness. Therefore, there is an urgent need for a general-purpose phase shifter material that is easy to integrate and offers excellent performance. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of the prior art. It proposes a high-dielectric tunable thin film based on orthogonal ferroelectric hafnium zirconate induced by a lead zirconate seed layer and its preparation method, thereby reducing losses, decreasing volume, shortening the preparation cycle, preventing environmental pollution, improving film performance, and meeting the requirements for phase shifter applications.

[0008] The technical approach to achieve the objective of this invention is to induce orthogonal ferroelectric hafnium zirconate-based thin films by introducing a lead zirconate seed layer, thereby realizing low-loss, miniaturized, short-cycle, and environmentally friendly high-dielectric tunable thin films.

[0009] Based on the above ideas, the technical solution of the present invention includes:

[0010] 1. A high-dielectric tunable thin film based on orthogonal ferroelectric hafnium zirconate-based induced by lead zirconate seed layer, comprising a substrate and a hafnium zirconate HZO layer, characterized in that a lead zirconate PZO layer is provided between the substrate and the hafnium zirconate HZO layer for inducing the hafnium zirconate-based molecule to become an orthogonal phase, thereby giving it ferroelectric properties.

[0011] Furthermore, the lead zirconate (PZO) layer has a thickness of 300-500 nm and a composition of PbZrO3.

[0012] Furthermore, the hafnium zirconate (HZO) layer has a thickness of 100-200 nm and a composition of Hf. 1-x Zr x O2, where x is the doping amount, which ranges from 0.01 to 0.99.

[0013] Furthermore, the substrate is made of quartz glass, sapphire, or silicon.

[0014] 2. A method for preparing a high-dielectric tunable thin film based on orthogonal ferroelectric hafnium zirconate induced by a lead zirconate seed layer, characterized in that it comprises:

[0015] S1) Weigh Pb(CH3COOH)2·3H2O and Zr(OC3H7)4 in a molar ratio of 1:1, dissolve and mix them, and then prepare a PbZrO3 precursor solution PZO.

[0016] S2) A wet film is prepared by spin-coating the precursor solution PZO onto a substrate, and then dried and pyrolyzed sequentially to obtain a single-layer PZO thin film.

[0017] S3) Repeat step S2) to obtain a multilayer PZO thin film with a thickness of 300-500 nm;

[0018] S4) Weigh out the raw material hafnium acetylacetone (HfC) 20 H 28 O8) and zirconium isopropoxide (C 12 H 28 O4Zr) was dissolved in a mixture of CH3COOH and CH3CH2OH, and the two mixtures were then thoroughly mixed to prepare an HZO precursor solution.

[0019] S5) The HZO-based precursor solution was spin-coated onto a PZO film, and then dried, pyrolyzed, and annealed sequentially to obtain a single-layer HZO film.

[0020] S6) Repeat step S5) to obtain a multilayer HZO thin film with a thickness of 100-200nm, thus completing the fabrication of the high-dielectric tunable thin film.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] Firstly, because the present invention has a lead zirconate (PZO) layer between the substrate and the hafnium zirconate (HZO) layer, it can get rid of the dependence on special metal electrodes such as titanium nitride (TiN) and tungsten (W), and achieve ferroelectric phase transformation without the need for electrode strain induction. Thus, thin films can be synthesized at low temperatures of 450°C to 550°C, and crystallization annealing can be completed directly in the atmosphere without the need for a nitrogen atmosphere. The operation is convenient and efficient, providing a new feasible path for the low-cost integration and large-scale fabrication of ferroelectric functional devices.

[0023] Secondly, this invention successfully induces orthogonal ferroelectric hafnium zirconate-based thin films by utilizing a lead zirconate seed layer. This not only leverages the compatibility of hafnium zirconate-based materials with CMOS processes to overcome the limitations of traditional phase shifters, such as large size, high power consumption, low integration, and the incompatibility between barium strontium titanate thin films and silicon-based processes, thus achieving miniaturization and high integration, but also significantly reduces lead content by utilizing an ultra-thin lead zirconate seed layer, avoiding environmental risks, and simplifies the preparation process, laying a solid foundation for industrial mass production. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the orthogonal ferroelectric HZO thin film induced by the PZO seed layer prepared according to the present invention;

[0025] Figure 2 This is a schematic diagram of the preparation process of orthogonal ferroelectric HZO thin films induced by PZO seed layer according to the present invention;

[0026] Figure 3The XRD patterns of the PZO seed layer and HZO film obtained in Example 1 of the present invention are shown. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited to the scope shown in the embodiments. These embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, after reading the contents of this invention, those skilled in the art can make various modifications to the present invention, and these equivalent changes also fall within the scope defined by the appended claims.

[0028] Reference Figure 1 This invention relates to a high-dielectric-tunable thin film based on orthogonal ferroelectric hafnium zirconate induced by a lead zirconate seed layer, comprising a substrate, a lead zirconate (PZO) layer, and a hafnium zirconate (HZO) layer, wherein:

[0029] The substrate is made of quartz glass, sapphire, or silicon.

[0030] The lead zirconate (PZO) layer, with a thickness of 300-500 nm and a composition of PbZrO3, is located on the substrate and is used to induce the hafnium zirconate group to become an orthorhombic phase, thereby giving it ferroelectric properties.

[0031] The hafnium zirconate (HZO) layer has a thickness of 100-200 nm and a composition of Hf. 1-x Zr x O2, with a doping amount x ranging from 0.01 to 0.99, is located above the lead zirconate (PZO) layer.

[0032] Reference Figure 2 This invention provides three embodiments for preparing orthogonally ferroelectric hafnium zirconate-based high-dielectric tunable thin films induced by lead zirconate seed layers.

[0033] Example 1: A lead zirconate (PZO) layer with a thickness of 300 nm and a composition of PbZrO3 was fabricated on a silicon substrate. A hafnium zirconate (HZO) layer with a thickness of 50 nm and the chemical formula Hf was also fabricated. 1-x Zr x Hf in O2 with x=0.5 0.5 Zr 0.5 O2 ferroelectric thin film.

[0034] Step 1: Prepare PbZrO3 precursor solution.

[0035] Pb(CH3COOH)2·3H2O and Zr(OC3H7)4 were weighed out in a molar ratio of 1:1.

[0036] Pb(CH3COOH)2·3H2O was dissolved in a mixed solvent of CH3COOH and CH3CH2OH;

[0037] Zr(OC3H7)4 was dissolved in a mixed solvent of CH3COOH and CH3CH2OH;

[0038] The two solutions were thoroughly mixed and stirred at 60°C for 2 hours and then left to stand for 24-30 hours to obtain a PbZrO3 precursor solution with a concentration of 0.1 mol / L.

[0039] Step 2: Prepare PZO thin film.

[0040] 2.1) The PZO precursor solution obtained in step 1 was spin-coated onto a Si substrate at a speed of 2000 rpm for 30 s using a spin coater to obtain a wet film;

[0041] 2.2) The wet film obtained in step 2.1) is first dried on a hot plate at 150°C for 5 min, and then pyrolyzed on a hot plate at 350°C for 5 min to obtain a PZO film.

[0042] 2.3) Repeat steps 2.1) and 2.2) a total of 6 times to obtain 6 PZO thin films with a thickness of 300 nm, i.e. seed layers.

[0043] Step 3: Preparation of Hf 0.5 Zr 0.5 O2 precursor solution.

[0044] 3.1) First, weigh out HfC according to a molar ratio of 1:1. 20 H 28 O8, C 12 H 28 O4Zr, raw material HfC 20 H 28 O8 dissolves in a mixture of CH3COOH and CH3CH2OH at 60℃;

[0045] 3.2) Then C 12 H 28 O4Zr dissolves in a mixture of CH3COOH and CH3CH2OH at 60℃;

[0046] 3.3) Then, the two mixtures were stirred at 60°C for 2 hours and mixed again, and then left to stand for 24 hours to obtain Hf with a concentration of 0.1 mol / L. 0.5 Zr 0.5 O2 precursor solution.

[0047] Step 4: Preparation of Hf 0.5 Zr 0.5 O2 thin film.

[0048] 4.1) Take the Hf obtained in step 3.3) 0.5 Zr 0.5The O2 precursor solution was spin-coated onto the PZO seed layer at 2000 rpm for 30 seconds using a spin coater to obtain a wet film.

[0049] 4.2) The wet film obtained in step 4.1) is first dried on a hot plate at 150°C for 5 min, then pyrolyzed on a hot plate at 350°C for 10 min, and finally annealed at 350°C in air for 3 min. A layer of Hf is obtained. 0.5 Zr 0.5 O2 thin film;

[0050] 4.3) Repeat steps 4.1) and 4.2) once to obtain a 50nm thick Hf layer. 0.5 Zr 0.5 O2 thin film.

[0051] Example 2: A lead zirconate (PZO) layer with a thickness of 400 nm and a composition of PbZrO3 was fabricated on a quartz glass substrate, and a hafnium zirconate (HZO) layer with a thickness of 100 nm and chemical formula Hf was fabricated. 1-x Zr x Hf in O2 with x=0.7 0.3 Zr 0.7 O2 ferroelectric thin film.

[0052] Step 1: Prepare PbZrO3 precursor solution.

[0053] The implementation of this step is the same as step 1 in Example 1.

[0054] Step 2: Prepare PZO thin film.

[0055] 2-1) The PZO precursor solution obtained in step one was spin-coated onto a Si substrate at a speed of 4000 rpm for 35 s using a spin coater to obtain a wet film.

[0056] 2-2) The wet film obtained in step 2-1) is first dried on a hot plate at 250°C for 25 min, and then pyrolyzed on a hot plate at 450°C for 15 min to obtain a PZO film.

[0057] 2-3) Repeat steps 2-1) and 2-2) a total of 8 times to obtain 8 PZO thin films with a thickness of 400 nm.

[0058] Step 3: Preparation of Hf 0.3 Zr 0.7 O2 precursor solution.

[0059] 3-1) Weigh out HfC according to a molar ratio of 3:7. 20 H 28 O8, C 12 H 28 O4Zr, and the raw material HfC 20 H28 O8 dissolves in a mixture of CH3COOH and CH3CH2OH at 60℃;

[0060] 3-2) C 12 H 28 O4Zr dissolves in a mixture of CH3COOH and CH3CH2OH at 60℃;

[0061] 3-3) The two mixtures were stirred at 80℃ for 2 hours, mixed again, and left to stand for 27 hours to obtain Hf with a concentration of 0.1 mol / L. 0.3 Zr 0.7 O2 precursor solution.

[0062] Step 4: Preparation of Hf 0.3 Zr 0.7 O2 thin film.

[0063] 4-1) Take the Hf obtained in step 3-3) 0.3 Zr 0.7 The O2 precursor solution was spin-coated onto the PZO seed layer at a speed of 4000 rpm for 35 seconds using a spin coater to obtain a wet film.

[0064] 4-2) The wet film obtained in step 4-1) is first dried on a hot plate at 250°C for 25 min, then pyrolyzed on a hot plate at 400°C for 20 min, and finally annealed at 450°C in air for 4 min. A layer of Hf is obtained. 0.3 Zr 0.7 O2 thin film;

[0065] 4-3) Repeat steps 4-1) and 4-2) twice to obtain two Hf layers with a thickness of 100 nm. 0.3 Zr 0.7 O2 thin film.

[0066] Example 3: A lead zirconate (PZO) layer with a thickness of 500 nm and a composition of PbZrO3 was fabricated on a sapphire substrate, and a hafnium zirconate (HZO) layer with a thickness of 150 nm and chemical formula Hf was fabricated. 1-x Zr x Hf in O2 with x=0.2 0.8 Zr 0.2 O2 ferroelectric thin film.

[0067] Step A: Prepare PbZrO3 precursor solution.

[0068] Pb(CH3COOH)2·3H2O and Zr(OC3H7)4 were weighed in a molar ratio of 1:1. Pb(CH3COOH)2·3H2O was dissolved in a mixed solvent of CH3COOH and CH3CH2OH; Zr(OC3H7)4 was dissolved in a mixed solvent of CH3COOH and CH3CH2OH. The two solutions were then thoroughly mixed and stirred at 60℃ for 2 h and allowed to stand for 24-30 h to obtain a 0.1 mol / L PbZrO3 precursor solution.

[0069] Step B: Prepare PZO thin film.

[0070] B1) The PZO precursor solution obtained in step B1) was spin-coated onto a Si substrate at a speed of 6000 rpm for 40 s using a spin coater to obtain a wet film.

[0071] B2) The wet film obtained in step B1) is first dried on a hot plate at 350°C for 45 min, and then pyrolyzed on a hot plate at 550°C for 30 min to obtain a PZO film.

[0072] B3) Repeat steps B1) and B2) a total of 10 times to obtain 10 PZO thin films with a thickness of 500 nm.

[0073] Step C: Preparation of Hf 0.8 Zr 0.2 O2 precursor solution.

[0074] C1) Weigh out HfC according to a molar ratio of 4:1. 20 H 28 O8, C 12 H 28 O4Zr, raw material HfC 20 H 28 O8 dissolves in a mixture of CH3COOH and CH3CH2OH at 60℃;

[0075] C2) will C 12 H 28 O4Zr dissolves in a mixture of CH3COOH and CH3CH2OH at 60℃;

[0076] C3) The two mixtures were stirred at 100℃ for 2 hours and then mixed again. After standing for 30 hours, Hf was obtained with a concentration of 0.1 mol / L. 0.8 Zr 0.2 O2 precursor solution.

[0077] Step D: Preparation of Hf 0.8 Zr 0.2 O2 thin film.

[0078] D1) Obtain Hf from step C30.8 Zr 0.2 The O2 precursor solution was spin-coated onto the PZO seed layer at 6000 rpm for 40 seconds using a spin coater to obtain a wet film.

[0079] D2) The wet film obtained in step D1) is first dried on a hot plate at 350°C for 45 min, then pyrolyzed on a hot plate at 450°C for 30 min, and finally annealed at 550°C in air for 5 min to obtain a layer of Hf. 0.8 Zr 0.2 O2 thin film;

[0080] D3) Repeat steps D1) and D2) a total of 3 times to obtain 3 layers of Hf with a thickness of 150nm. 0.8 Zr 0.2 O2 thin film.

[0081] The effectiveness of this invention can be further illustrated by test results:

[0082] This test used copper target Kα X-rays under the following conditions: ambient temperature 25°C, a scanning range of 2θ = 10~120°, a step angle of 0.01~0.02°, and a scanning speed of 1° / min. The PZO seed layer and HZO layer phase structures of the high-dielectric tunable thin film of Example 1 were tested. The results are as follows: Figure 3 As shown.

[0083] from Figure 3 It can be seen that both the PZO seed layer and the HZO layer of the thin film of the present invention are orthorhombic phases with a dense structure and no second phase is generated, indicating that the PZO seed layer can successfully induce the orthorhombic phase of the orthorhombic ferroelectric HZO base.

[0084] The above descriptions are merely a few specific examples of the present invention and do not constitute any limitation on the present invention. Obviously, those skilled in the art, after understanding the content and principles of the present invention, may make various modifications and changes in form and details without departing from the principles and structure of the present invention. For example, in addition to the PZO seed layer used in this experiment, a zirconium oxide (ZrO2) seed layer or other inducible orthorhombic phases of HZO can also be used. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A high-dielectric tunable thin film based on orthogonal ferroelectric hafnium zirconate induced by a lead zirconate seed layer, comprising a substrate (1) and a hafnium zirconate HZO layer (3), characterized in that, A lead zirconate PZO layer (2) is provided between the substrate (1) and the hafnium zirconate HZO layer (3) to induce the hafnium zirconate group to become an orthorhombic phase, so that it has ferroelectricity.

2. The thin film according to claim 1, characterized in that, The lead zirconate PZO layer (2) has a thickness of 300-500 nm and a composition of PbZrO3.

3. The thin film according to claim 1, characterized in that, The hafnium zirconate (HZO) layer (3) has a thickness of 100-200 nm and a composition of Hf. 1-x Zr x O2, where x is the doping amount, which ranges from 0.01 to 0.

99.

4. The thin film according to claim 1, characterized in that, The substrate is made of sapphire, quartz glass, or silicon.

5. A method for preparing a high-dielectric tunable thin film based on orthogonal ferroelectric hafnium zirconate induced by a lead zirconate seed layer, characterized in that, include: S1) Weigh Pb(CH3COOH)2·3H2O and Zr(OC3H7)4 in a molar ratio of 1:1, dissolve and mix them, and then prepare a PbZrO3 precursor solution PZO. S2) A wet film is prepared by spin-coating the precursor solution PZO onto a substrate, and then subjected to drying and pyrolysis to obtain a single film. PZO thin film; S3) Repeat step S2) to obtain a multilayer PZO thin film with a thickness of 300-500 nm; S4) Weigh out the raw material hafnium acetylacetone (HfC) 20 H 28 O8) and zirconium isopropoxide (C 12 H 28 O4Zr) was dissolved in a mixture of CH3COOH and CH3CH2OH, and the two mixtures were then thoroughly mixed to prepare an HZO precursor solution. S5) The HZO-based precursor solution was spin-coated onto a PZO film, and then dried, pyrolyzed, and annealed sequentially to obtain a single-layer HZO film. S6) Repeat step S5) to obtain a multilayer HZO thin film with a thickness of 100-200nm, thus completing the fabrication of the high-dielectric tunable thin film.

6. The method according to claim 5, characterized in that, The preparation of the PZO precursor solution in S1) is achieved by: Dissolve the weighed Pb(CH3COOH)2·3H2O in a mixed solvent of glacial acetic acid (CH3COOH) and ethanol (CH3CH2OH); dissolve the weighed Zr(OC3H7)4 in a mixed solvent of CH3COOH and CH3CH2OH; then stir the two solutions at 60℃ for 3-4 hours to mix them thoroughly, and let them stand for 24-30 hours to obtain a PZO precursor solution with a concentration of 0.1 mol / L.

7. The method according to claim 5, characterized in that, In step S2): The spin coating is performed at a speed of 2000-6000 rpm for a time of 30-40 seconds. The pyrolysis is performed at a temperature of 350-550℃ for a time of 5-45 minutes.

8. The method according to claim 5, characterized in that, Step S4) involves preparing the HZO precursor solution, which includes: raw material HfC 20 H 28 O8 powder is dissolved in a mixed liquid of CH3COOH and CH3CH2OH at 60℃; C 12 H 28 O4Zr powder was dissolved at 60°C in a mixture of CH3COOH and CH3CH2OH. The two mixtures were then heated to 50-100℃ and stirred for 3-4 hours, and then left to stand for 24-30 hours to obtain a 0.1 mol / L HZO precursor solution.

9. The method according to claim 5, characterized in that, In step S5): The spin coating is performed at a speed of 2000-6000 rpm for a time of 30-40 seconds. The pyrolysis is performed at a temperature of 350-550℃ for a time of 5-45 minutes.

10. The method according to claim 5, characterized in that, The annealing temperature in step S5) is 350-550℃, the annealing time is 3-5 min, and the annealing environment is air.

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