A hydrofluoric acid-free wet etching solution and its preparation method and application

Abstract

The present invention belongs to the technical field of electronic material micro-processing, and specifically relates to a hydrofluoric acid-free wet etching solution, its preparation method, and application. The etching solution is prepared by mixing purified water, hydrochloric acid, hydrogen peroxide, and nitric acid in a volume ratio of (1-5): (1-10): (0.1-3): (0.1-3). The etching solution does not contain highly toxic, volatile, and extremely corrosive hydrofluoric acid, has a simple formulation, is safer, significantly reduces harm to the human body and environmental pollution, and the required raw materials are more readily available. The etching solution can cleanly, thoroughly, and efficiently (requiring only 10-100 seconds) remove a single ferroelectric film material or a multilayer ferroelectric composite film material from the surface of a Si, SiO2, or Pt substrate in one go, thereby obtaining an etched pattern with complete, clear edges and virtually no lateral corrosion.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic material micro-processing, namely, a wet etching solution in a photolithography process, and particularly relates to a wet etching solution that does not contain hydrofluoric acid, and a preparation method and application thereof. Background Art

[0002] Ferroelectric film materials, as low-dimensional microelectronic functional materials, have broad application prospects in sensors, actuators, memory, micro-electromechanical systems, and other fields due to their diverse functional properties. In the preparation and micro-nanofabrication of ferroelectric film materials, a variety of sophisticated process technologies are indispensable to achieve their specific functions and precise structural construction. Among them, etching technology is a critical micro-nanofabrication process. Etching technology is a process that can selectively remove materials at the microscopic level. It can precisely remove specific areas of ferroelectric film materials according to pre-designed structural patterns, thereby shaping the required microstructure and circuit layout, laying the foundation for the effective application of ferroelectric film materials in various electronic devices.

[0003] Etching technology mainly covers two types: dry etching and wet etching. Although dry etching performs well in precise patterning and has good anisotropy, the equipment required is expensive, the etching rate is slow, and it takes a long time. In addition, the photoresist mask is prone to carbonization during the long etching process, making the photoresist difficult to effectively remove later. In comparison, the wet etching process occupies an extremely important position in the field of high-precision micromachining of materials due to its low raw material cost, fast etching rate, and excellent etching efficiency. This process mainly relies on the specific chemical reaction between the etching solution and the processed material to achieve the selective removal of specific areas of the material to construct the desired microstructure and device pattern.

[0004] However, the currently widely used wet etching solutions have exposed a series of serious problems during actual use, which has greatly restricted the further development of material micro-nano processing technology. First, many existing etching solutions are often unable to achieve clear and definite pattern contours when etching ferroelectric film materials, and are prone to unnecessary lateral corrosion, which makes it impossible to accurately control the critical dimensions of micro devices. Secondly, the etching rate of traditional ferroelectric film material etching solutions is generally low, usually several minutes or even tens of minutes. The long etching time not only means a significant reduction in production efficiency and increased production costs, but also introduces more process variables and uncertainties. Moreover, the long-term corrosion immersion of the etching material will cause permanent damage to the mask photoresist on its surface, causing the mask to fail, and the material in non-target areas will also be etched, ultimately causing damage to the device structure and loss of functional characteristics.

[0005] Of particular note is that many wet etchants currently used for ferroelectric film materials contain hydrofluoric acid (HF). HF is volatile, highly corrosive, and toxic, posing a significant threat to operator safety during use. Even minimal exposure can cause severe skin burns and respiratory damage, endangering life. Consequently, the use of HF is subject to strict regulations. Furthermore, wastewater containing HF is difficult to dispose of. Improper handling can cause long-term and irreversible ecological pollution, which runs counter to the current global emphasis on green environmental protection and sustainable development.

[0006] Existing technologies, such as the Chinese invention patent with authorization publication number CN 101381893 B, devise an etchant for CdGeAs2 crystals to avoid the use of volatile, corrosive, and highly toxic hydrofluoric acid (HF). The etchant is composed of a mixture of hydrochloric acid, nitric acid, and purified water in a volume ratio of 1:1:1. However, this etchant is specific to CdGeAs2 crystals and requires complex pre-etching sample preparation, such as grinding and polishing, as well as post-etching sample drying at high temperatures for extended periods (40-60°C for at least 2 hours). Furthermore, the CdGeAs2 crystals must be cleaned with an alkaline solution (such as sodium hydroxide) after etching, significantly increasing the time, cost, and complexity of the CdGeAs2 crystal etching process and significantly reducing its industrial efficiency. In particular, this patent fails to effectively control the etching rate of the CdGeAs2 crystals and cannot precisely define the etching area of ​​the CdGeAs2 crystals. Summary of the Invention

[0007] Existing wet etching solutions for ferroelectric film materials suffer from drawbacks such as difficulty in precisely controlling the etched pattern profile, poor clarity, slow and difficult-to-regulate etch rates, prone to photoresist mask failure, and environmental and human health hazards. The present invention addresses these shortcomings by providing a hydrofluoric acid-free wet etching solution and a simplified preparation method thereof, thereby producing etched patterns of ferroelectric film materials with clear profiles and a high etching ratio.

[0008] In order to achieve the above object, the technical solution of the present invention is:

[0009] In a first aspect, the present invention provides a hydrofluoric acid-free wet etching solution for wet etching of ferroelectric film materials, comprising pure water, hydrochloric acid, hydrogen peroxide and nitric acid, but excluding hydrofluoric acid; the volume ratio of the pure water: hydrochloric acid: hydrogen peroxide: nitric acid is (1-5): (1-10): (0.1-3): (0.1-3).

[0010] In some other embodiments, the mass concentration of the hydrochloric acid is 36-38%;

[0011] Alternatively, the mass concentration of the hydrogen peroxide is 25-30%;

[0012] Alternatively, the mass concentration of the nitric acid is 65-68%;

[0013] Alternatively, the pure water is one of ultrapure water, deionized water and distilled water.

[0014] In some other embodiments, the hydrochloric acid, hydrogen peroxide, and nitric acid are all of analytical grade.

[0015] The etching solution of the present invention does not contain highly toxic, volatile, and extremely corrosive hydrofluoric acid. The raw materials in the etching solution are all inexpensive and readily available, making it easy to promote and apply. Hydrochloric acid is used as an etchant to etch the ferroelectric thin film, and purified water is used as a diluent to adjust the etchant concentration. Nitric acid is used to control the etching rate of the etching solution, resulting in good etching selectivity for the ferroelectric film material. Hydrogen peroxide is used to protect the photoresist mask area, precisely define the etching area, and leave no residue in the etched area, ensuring a regular and clear etching profile and significantly enhancing the etching effect. Through the interaction between hydrochloric acid, hydrogen peroxide, nitric acid and pure water, single ferroelectric film materials (such as bismuth ferrite, barium titanate, lead zirconate titanate, strontium titanate films) or multi-layer ferroelectric composite film materials (such as multi-layer composite films of bismuth ferrite, barium titanate, lead zirconate titanate, strontium titanate, and lanthanum nickelate) on the surface of Si, SiO2 or Pt substrates can be cleanly, thoroughly and efficiently (the time required is only 10 to 100 seconds) removed at one time, obtaining an etched pattern with complete and clear edges and almost no lateral corrosion.

[0016] In some other embodiments, the ferroelectric film material is a single film material or a multi-layer composite film material.

[0017] In some other embodiments, the single film material is one of bismuth ferrite, barium titanate, lead zirconate titanate, and strontium titanate thin films;

[0018] The multilayer composite film material is at least two of bismuth ferrite, barium titanate, lead zirconate titanate, strontium titanate, and lanthanum nickelate.

[0019] In a second aspect, the present invention provides a method for preparing the hydrofluoric acid-free wet etching solution described in the first aspect, comprising uniformly mixing purified water and hydrochloric acid at room temperature, and then sequentially adding hydrogen peroxide and nitric acid and mixing them uniformly to obtain the wet etching solution.

[0020] In a third aspect, the present invention provides use of the hydrofluoric acid-free wet etching solution described in the first aspect in wet etching of ferroelectric film materials.

[0021] In a fourth aspect, the present invention provides a method for wet etching a ferroelectric film material, comprising the following steps:

[0022] (1) Spinning a photoresist on the surface of the ferroelectric film material to be etched, and after treatment, obtaining a ferroelectric film material with a patterned photoresist layer;

[0023] (2) etching the ferroelectric film material with the patterned photoresist layer in the wet etching solution without hydrofluoric acid described in the first aspect, and removing the etching solution remaining on the surface of the ferroelectric film material to obtain the etched ferroelectric film material;

[0024] (3) Placing the etched ferroelectric film material in a photoresist stripping solution to strip the photoresist, and after removing the photoresist stripping solution, obtaining a ferroelectric film material containing a graphical etching pattern.

[0025] In some other embodiments, in step (1), the treatment is sequentially performed through pre-baking, exposure, post-baking, development and film hardening.

[0026] In some other embodiments, in step (2), the etching temperature is 25 to 60° C., and the etching time is 10 to 100 seconds;

[0027] Alternatively, in step (3), the photoresist stripping solution is one of acetone, dimethyl sulfoxide, N-methylpyrrolidone and N-ethylpyrrolidone, and the stripping time is 1 to 5 minutes.

[0028] Beneficial effects of the present invention:

[0029] 1. The hydrofluoric acid-free wet etching solution provided by the present invention does not contain any hydrofluoric acid component, making it safer for personnel to operate, conforming to the concepts of green environmental protection and sustainable development, and can also reduce the difficulty and cost of waste liquid treatment, promote ecological balance, improve environmental quality, and protect personal safety.

[0030] 2. Existing etchants for ferroelectric film materials generally have low etching rates, typically several minutes or even tens of minutes. Excessively long etching times can permanently damage the photoresist. The present invention provides a hydrofluoric acid-free wet etching solution and its preparation method, which has an etching time of 10 to 100 seconds. Compared with many other etching solutions, it has a higher etching rate and a higher etching ratio, which can significantly shorten the etching time and improve production efficiency.

[0031] 3. The wet etching solution provided by the present invention can precisely define the etched area during micro-scale etching operations, resulting in clear and regular etching boundaries, effectively avoiding the edge blurring and lateral corrosion problems often associated with traditional etching solutions. For devices, the well-defined etched pattern ensures precise control of critical dimensions of microelectronic devices, thereby facilitating the production of high-density integrated microdevice patterns.

[0032] 4. The etching solution provided by the present invention is prepared from purified water, hydrochloric acid, hydrogen peroxide and nitric acid. Its components and preparation method are simple, and the raw materials used are all conventional chemical reagents. They are easy to obtain and low in cost, which is conducive to large-scale industrial implementation.

[0033] 5. The etching solution provided by the present invention is applicable to a wide range of material systems and can etch a variety of film materials such as lanthanum nickelate, bismuth ferrite, barium titanate, lead zirconate titanate, and strontium titanate. The film material that can be etched can be a single film system of these film materials or a multilayer composite film system composed of these film materials, such as bismuth ferrite / lanthanum nickelate composite film, bismuth ferrite / barium titanate composite film, lead zirconate titanate / barium titanate composite film, barium titanate / strontium titanate composite film, bismuth ferrite / barium titanate / lanthanum nickelate composite film, barium titanate / bismuth ferrite / barium titanate composite film, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0035] Figure 1 Scanning electron microscope images of the surface patterning of the bismuth ferrite / lanthanum nickelate double-layer film sample before and after etching in Example 1 of the present invention, (a) before etching, (b) after etching;

[0036] Figure 2 This is a photo of the bismuth ferrite / lanthanum nickelate double-layer film sample after etching in half of the photoresist mask area in Example 1 of the present invention;

[0037] Figure 3 This is a scanning electron microscope image of the bismuth ferrite / lanthanum nickelate double-layer film sample after etching in Example 1 of the present invention;

[0038] Figure 4 Scanning electron microscope images of the barium titanate film material sample and the pattern after etching, (a) actual image, (b) pattern after etching;

[0039] Figure 5 The actual image of the lead zirconate titanate film material sample and the scanning electron microscope image of the pattern after etching, (a) actual image, (b) pattern after etching;

[0040] Figure 6 The actual image of the strontium titanate film material sample and the scanning electron microscope image of the pattern after etching, (a) actual image, (b) pattern after etching. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further described below through specific embodiments.

[0042] In the following examples, the raw materials are purified water, hydrochloric acid, hydrogen peroxide, and nitric acid, wherein the hydrochloric acid, hydrogen peroxide, and nitric acid are all analytical grade, the mass concentration of hydrochloric acid is 36%, the mass concentration of hydrogen peroxide is 30%, and the mass concentration of nitric acid is 65%.

[0043] Example 1

[0044] A hydrofluoric acid-free wet etching solution is used to etch a bismuth ferrite / lanthanum nickelate double-layer composite film. The double-layer film is based on a silicon substrate with a platinum layer, forming a bismuth ferrite / lanthanum nickelate / platinum / silicon architecture. The bismuth ferrite layer in the double-layer film is approximately 100 nm thick, and the lanthanum nickelate layer is approximately 300 nm thick. It should be noted that this embodiment is applicable to etching either bismuth ferrite or lanthanum nickelate single films. The specific etching process is as follows:

[0045] (1) Preparation of etching solution

[0046] The wet etching solution for ferroelectric film materials that does not contain hydrofluoric acid is prepared from pure water, hydrochloric acid, hydrogen peroxide, and nitric acid. The volume ratio of pure water: hydrochloric acid: hydrogen peroxide: nitric acid is 1:1:0.5:0.5, the mass concentration of hydrochloric acid is 36%, the mass concentration of hydrogen peroxide is 30%, and the mass concentration of nitric acid is 65%.

[0047] Pure water, hydrochloric acid, hydrogen peroxide, and nitric acid are measured respectively according to the above volume ratio. At room temperature, the pure water and hydrochloric acid are first mixed evenly, and then hydrogen peroxide and nitric acid are added in sequence and mixed evenly to form a wet etching solution for the ferroelectric film material. The etching solution does not contain any hydrofluoric acid component.

[0048] (2) Photoresist coating on the surface of bismuth ferrite / lanthanum nickelate double layer film

[0049] A photoresist film layer was uniformly coated on the surface of the bismuth ferrite / lanthanum nickelate double-layer film by spin coating, and then the film was processed by pre-baking (110℃, 5 minutes), exposure (55 seconds), post-baking (120℃, 5 minutes), development (45 seconds), and hardening (130℃, 20 minutes) to obtain a patterned photoresist film layer.

[0050] (3) Etching of Bismuth Ferrite / Lannium Nickelate Double-layer Film

[0051] The bismuth ferrite / lanthanum nickelate double-layer film coated with the patterned photoresist is immersed in the etching solution prepared in step (1) at room temperature (about 25° C.) for 15 seconds, and then the residual etching solution is rinsed with deionized water and blown dry with nitrogen; then it is immersed in N-methylpyrrolidone (NMP) solution for 3 minutes to remove the photoresist on the surface of the bismuth ferrite / lanthanum nickelate double-layer film, thereby obtaining the desired bismuth ferrite / lanthanum nickelate double-layer film etching pattern.

[0052] The surface of the etched bismuth ferrite / lanthanum nickelate double-layer film was observed using a scanning electron microscope. Figure 1 As shown, it can be seen that the square pattern of the membrane material sample after etching and degumming has a clear outline, very regular edges, and no lateral etching.

[0053] Figure 2 This is a photo of the bismuth ferrite / lanthanum nickelate double-layer film sample after etching half of the photoresist mask area. Figure 2 The left side of the bismuth ferrite / lanthanum nickelate bilayer film, without a photoresist mask, shows a bright area after etching, indicating that the bismuth ferrite / lanthanum nickelate bilayer has been completely etched. The right side of the bismuth ferrite / lanthanum nickelate bilayer film, with a photoresist mask, still shows an intact area after etching, forming a sharp contrast with the area on the left, indicating that the photoresist has played a good protective role for the film material. Moreover, after etching, the boundaries between the left and right areas are clear and regular, intuitively demonstrating that the wet etching solution without hydrofluoric acid described in the present invention can etch thoroughly without lateral etching.

[0054] Figure 3 for Figure 2 A scanning electron microscope image of a bismuth ferrite / lanthanum nickelate bilayer film sample. This SEM image more precisely and clearly shows the difference between the left and right regions of the bismuth ferrite / lanthanum nickelate bilayer film after etching. This significant contrast difference is due to the different film thicknesses on both sides. Furthermore, the boundary between the two regions is very clear, further demonstrating that the hydrofluoric acid-free wet etching solution described in this invention can etch accurately and without lateral etching.

[0055] Example 2

[0056] The difference from Example 1 is that in step (1), the volume ratio of pure water: hydrochloric acid: hydrogen peroxide: nitric acid is 1:5:1:1 or 1:5:1:2 or 1:5:2:1, and the other steps and process parameters are the same as those in Example 1.

[0057] Compared to Example 1, the etchant in this embodiment, which has a ratio of pure water: hydrochloric acid: hydrogen peroxide: nitric acid = 1:5:1:1, contains a higher amount of hydrochloric acid. As an etchant, hydrochloric acid reacts more rapidly with the bismuth ferrite / lanthanum nickelate bilayer film, resulting in a faster etching rate. However, while a high hydrochloric acid content can significantly increase the etching rate, it can also easily cause lateral corrosion of the etched pattern and damage the photoresist, resulting in blurred and irregular pattern outlines. Therefore, in this embodiment, the etchant, which has a ratio of pure water: hydrochloric acid: hydrogen peroxide: nitric acid = 1:5:1:2 or 1:5:2:1, can compensate for the side effects of the excessively fast etching rate caused by high hydrochloric acid content by adjusting the relative amounts of hydrogen peroxide and nitric acid. Nitric acid has a certain "passivating effect," which can moderate the etching rate of the etchant and improve its etching selectivity for ferroelectric film materials. Hydrogen peroxide has strong oxidizing properties, which can protect the photoresist mask area and improve the lateral corrosion problem of the etchant, thereby ensuring a regular and clear etching outline and enhancing the etching effect.

[0058] Example 3

[0059] The difference from Example 1 is that the temperature of the etching solution in step (3) is 40° C., 50° C., or 60° C., and the other steps and process parameters are the same as those in Example 1.

[0060] Compared to Example 1, appropriately increasing the etching temperature of the etching solution during the etching process of the bismuth ferrite / lanthanum nickelate bilayer film facilitates a more complete and thorough reaction between the etching solution and the bismuth ferrite / lanthanum nickelate bilayer film, significantly improving the etching rate and enabling more effective etching of the ferroelectric film material. If the temperature is too high, the evaporation of the etching solution will increase, which will weaken the etching efficiency of the etching solution. Furthermore, excessively high temperatures will cause the nitric acid and hydrogen peroxide components in the etching solution to oxidize the photoresist on the surface of the film material, making the photoresist difficult to remove. Therefore, the etching temperature of the hydrofluoric acid-free wet etching solution described in the present invention is preferably between room temperature and 60°C.

[0061] Example 4

[0062] The difference from Example 1 is that the etching time in step (3) is 30 seconds, 50 seconds or 90 seconds, and the other steps and process parameters are the same as those in Example 1.

[0063] Compared to Example 1, the etching time for the bismuth ferrite / lanthanum nickelate bilayer film in this example is extended. Properly extending the etching time facilitates a more complete and thorough reaction between the etching solution and the bismuth ferrite / lanthanum nickelate bilayer film, resulting in a clean, residue-free etched area. Excessively long etching times can cause lateral corrosion of the ferroelectric film material, resulting in a blurred and irregular etched profile. Furthermore, excessively long etching times can damage the photoresist on the film surface, making it difficult to remove and effectively protect the ferroelectric film material. Therefore, the hydrofluoric acid-free wet etching solution, preparation method, and application described herein preferably have an etching time of 15 to 90 seconds.

[0064] Example 5

[0065] The difference from Example 1 is that the photoresist stripping solution in step (3) is acetone or dimethyl sulfoxide (DMSO) or N-ethylpyrrolidone (NEP), and the other steps and process parameters are the same as those in Example 1.

[0066] The acetone, dimethyl sulfoxide (DMSO), or N-ethylpyrrolidone (NEP) photoresist stripping solutions provided in this embodiment are all capable of removing the photoresist layer on the surface of the bismuth ferrite / lanthanum nickelate bilayer film. Considering the photoresist stripping rate and effectiveness, the preferred photoresist stripping solution for the hydrofluoric acid-free wet etching solution, its preparation method, and its application described in the present invention is N-methylpyrrolidone (NMP) or acetone.

[0067] Example 6

[0068] Different from Example 1, the ferroelectric film material wet etching solution that does not contain hydrofluoric acid is used for a single film material system of barium titanate, lead zirconate titanate and strontium titanate, or a multilayer composite film system composed of these thin film materials. The specific etching time depends on the composition of the film material system and the thickness of the film layer. The other steps and process parameters are the same as those in Example 1.

[0069] Figure 4 The figure is a physical picture of a barium titanate film material sample and a scanning electron microscope picture of the pattern after etching, indicating that the etching solution of the present invention can effectively etch the barium titanate film material.

[0070] Figure 5 The figure is a physical picture of a lead zirconate titanate film material sample and a scanning electron microscope picture of the pattern after etching, indicating that the etching solution of the present invention can effectively etch the lead zirconate titanate film material.

[0071] Figure 6 The figure is a physical picture of a strontium titanate film material sample and a scanning electron microscope picture of the pattern after etching, indicating that the etching solution of the present invention can effectively etch the strontium titanate film material.

[0072] The above etching results show that the hydrofluoric acid-free wet etching solution prepared in Examples 1 to 6 has an excellent etching effect on ferroelectric film materials.

[0073] Comparative Example

[0074] Compared with Example 1, the comparative example has different components and component ratios of the etching solution in step (1), and the immersion time (etching time) of the bismuth ferrite / lanthanum nickelate double-layer film in the etching solution in step (3). The other steps and process parameters are the same as those in Example 1.

[0075] The following table shows the etching results of the bismuth ferrite / lanthanum nickelate bilayer film material in Example 1 using etching solutions of different compositions and ratios in Comparative Examples 1-6. The mass concentration of the hydrofluoric acid used was 40%, the mass concentration of the sulfuric acid used was 95%, and both were analytically pure. The mass concentrations of the other solutions used were the same as in Example 1.

[0076] Table 1 Etching results of bismuth ferrite / lanthanum nickelate double-layer film materials by etching solutions with different components and ratios

[0077]

[0078]

[0079] As can be seen from Table 1, compared to Example 1, the etching effects of the etching solutions in this comparative example on ferroelectric film materials are less than ideal. Specifically, although the etching solution in Comparative Example 1 can completely etch the bismuth ferrite / lanthanum nickelate film material, no matter how the component ratio is adjusted, the etching time is relatively short, the etching rate cannot be well controlled, and a complete pattern cannot be etched. The etching solution in Comparative Example 2, regardless of how the etching time and the component ratio are adjusted, destroys the photoresist and cannot etch the lanthanum nickelate layer. The etching solution in Comparative Example 3, regardless of how the etching time and the component ratio are adjusted, destroys the photoresist and cannot etch the bismuth ferrite / lanthanum nickelate double-layer film material. The etching solution in Comparative Example 4 can etch the bismuth ferrite / lanthanum nickelate double-layer film material, but no matter how the etching time and the component ratio are adjusted, the photoresist is easily destroyed, the double-layer film exhibits some lateral etching, and the etching profile lacks a clear and regular pattern. The etchant in Comparative Example 5 was able to etch the bismuth ferrite / lanthanum nickelate bilayer film, but the etching rate was slow, leaving some residual etched areas, and the etched outline was unclear. The etchant in Comparative Example 6 damaged the photoresist regardless of the etching time, and was unable to etch the bismuth ferrite / lanthanum nickelate bilayer film.

[0080] This shows that the hydrofluoric acid-free wet etching solution and its preparation method described in Examples 1 to 6 of the present invention have good etching effect on ferroelectric film materials, the edges of the etched patterns are regular and clear, and there is no lateral corrosion; and the etching solution and its preparation method are suitable for a variety of ferroelectric film materials, and can be used for single film material systems such as lanthanum nickelate, bismuth ferrite, barium titanate, lead zirconate titanate, and strontium titanate, or multilayer composite film material systems composed of these film materials.

[0081] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for wet etching of a ferroelectric film material, characterized in that: The following steps are involved: (1) Spinning a photoresist onto the surface of the ferroelectric film material to be etched, and after treatment, obtaining a ferroelectric film material with a patterned photoresist layer; (2) etching the ferroelectric film material with the patterned photoresist layer in a wet etching solution that does not contain hydrofluoric acid, and removing the etching solution remaining on the surface of the ferroelectric film material to obtain the etched ferroelectric film material; (3) placing the etched ferroelectric film material in a photoresist stripping solution to strip the photoresist, and after removing the photoresist stripping solution, obtaining a ferroelectric film material containing a patterned etching pattern; In step (2), the etching temperature is 25-60°C, and the etching time is 10-100 seconds; The wet etching solution not containing hydrofluoric acid comprises pure water, hydrochloric acid, hydrogen peroxide and nitric acid, and does not contain hydrofluoric acid; the volume ratio of pure water: hydrochloric acid: hydrogen peroxide: nitric acid is (1-5): (1-10): (0.1-3): (0.1-3); The mass concentration of the hydrochloric acid is 36-38%; The mass concentration of the hydrogen peroxide is 25-30%; The mass concentration of the nitric acid is 65-68%; The pure water is one of ultrapure water, deionized water and distilled water; The ferroelectric film material is a single film material or a multi-layer composite film material; The single film material is one of bismuth ferrite, barium titanate, lead zirconate titanate and strontium titanate thin films; The multilayer composite film material is at least two of bismuth ferrite, barium titanate, lead zirconate titanate, strontium titanate, and lanthanum nickelate.

2. The method for wet etching of ferroelectric film material according to claim 1, characterized in that: The hydrochloric acid, hydrogen peroxide and nitric acid are all of analytical grade.

3. The method for wet etching of ferroelectric film material according to claim 1, characterized in that: In step (1), the treatment is sequentially performed through pre-baking, exposure, post-baking, development and film hardening.

4. The method for wet etching of ferroelectric film material according to claim 1, characterized in that: In step (3), the photoresist stripping solution is one of acetone, dimethyl sulfoxide, N-methylpyrrolidone and N-ethylpyrrolidone, and the stripping time is 1 to 5 minutes.

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