Titanium etching solution for wafer level packaging and preparation method and application thereof

Abstract

The invention discloses a titanium etching solution for wafer level packaging and a preparation method and application thereof. The titanium etching solution is composed of a component A and a component B. The component A is composed of, by mass, 2-20% of inorganic base, 1-15% of inorganic acid, 0.5-5% of pH stabilizer and the balance water. And the component B comprises the following raw materials in percentage by mass: 4.5-30% of hydrogen peroxide, 0.1-0.5% of an organic phosphine compound, 0.01-0.1% of a surfactant and the balance of water. When the titanium etching solution is heated to 25-55 DEG C, the titanium-containing wafer can be well and specifically etched, and the titanium etching solution has the advantages of being small in lateral etching amount, free of residues, long in service life and the like, and can be widely applied to titanium etching in integrated circuits.

Description

Technical Field

[0001] The invention belongs to the technical field of etching liquids, and in particular relates to a titanium etching liquid for wafer-level packaging and a preparation method and application thereof. Background Art

[0002] With the continuous development of integrated circuit technology, the integration of chips is getting higher and higher. The traditional packaging method has been gradually eliminated. Wafer Level Package (WLP) is the mainstream process and technical direction of chip packaging in the future. WLP technology has excellent performance and can pave the way for the integration of semiconductor manufacturing process and packaging process. It has received great attention since its birth. The key processes of WLP include bumping and rewiring, that is, connecting the I / O (input / output port) on the chip to the packaging carrier and packaging pins by metal wire bonding. However, with the miniaturization of IC chip size and the high integration scale, the distance between pins needs to be continuously reduced and the number continues to increase. When the I / O pitch is reduced to below 70μm, new technologies need to be found to replace the wire bonding technology that cannot be applied.

[0003] At present, wafer-level packaging uses rewiring technology to solve this problem. Rewiring technology refers to the technology of arranging each chip on the periphery of the I / O aluminum soldering area on the IC, transforming it into an array distribution soldering area or other required distribution pattern soldering area through the redistribution layer (RDL), and finally forming solder bumps. RDL can not only arrange the solder pads distributed around into regular array distribution pads through simple changes, increase the pad area or increase the number of I / O, but also integrate passive devices in the rewiring layer to further improve the integration of devices.

[0004] In RDL, the bump process has long been the most important part in the field of electronic packaging reliability, and most reliability issues are directly related to the quality of the bumps. Under-bump metallization systems (UBM) include Al / Ni / Cu systems, Cr / Cu / Au systems, and Ti / Ni / Au systems. In order to reduce the use of metal types, Ti with a thickness of less than 1000Å can also be directly used as an adhesion layer and barrier layer to prevent Cu metal from diffusing on the silicon substrate. Examples of technologies for processing Ti metal films to form wiring microstructure patterns include wet etching technology and dry etching technology. Among them, wet etching technology uses chemical reagents to corrode the metal film that is not masked by photoresist to form a metal pattern. Wet etching technology uses chemical reagents for etching, has high production efficiency, is easy to operate, does not require the use of complex precision equipment, and can etch a large area of ​​substrate uniformly over a large area. However, wet etching will cause side etching, and excessive side etching will hollow out the bottom of the line and cause it to fall off. Mixed acid system titanium etching solution can achieve the best etching effect according to different acid types and concentrations, but this type of etching solution has poor metal selectivity and is corrosive to metals such as titanium, copper, and aluminum. Alkaline hydrogen peroxide etching solution has good etching ability on titanium and almost no corrosion to metals such as copper, and has good application prospects. However, it is limited by the sensitivity of hydrogen peroxide itself to free metal ions and pH. High free metal ion concentration and high pH will accelerate the self-decomposition of hydrogen peroxide and reduce the life of the etching solution.

[0005] Chinese patent CN110462799A discloses an etching solution composition and an etching method for a titanium layer or a titanium-containing layer; the etching solution composition comprises a compound according to the example, hydrogen peroxide and an alkaline compound, and has a pH of 7-11. It can be used to etch a titanium layer or a titanium-containing layer on an oxide semiconductor, and can inhibit damage to the oxide semiconductor layer, and can etch titanium at a sufficient etching rate.

[0006] European patent EP3436621B discloses a solution and method for etching titanium-based materials. The solution for etching titanium-based materials contains 27-39 wt% potassium hydroxide, 0.002-0.02 wt% 1,2-diaminocyclohexane-N,N,N,Ntetraacetic acid (CDTA), and the balance is water. The solution can selectively etch the titanium-based barrier layer onto copper, aluminum and tin or their alloys while easily maintaining good control over the etching profile.

[0007] However, during the etching process, forward etching and lateral etching will occur simultaneously, and lateral etching will produce undercut. Undercut will affect the reliability and strength of the micro-bumps. When the pitch of the bumps is reduced to a certain extent, if the undercut is too large, the bumps will be squeezed, causing changes in the physical morphology. At the same time, the contact area between the bumps and the wafer becomes smaller, reducing the electron flow from the bumps to the wafer, affecting the stability and reliability of the electrical connection. In order to solve this problem, it is necessary to reduce lateral drilling and improve the strength of the micro-bumps themselves. The smaller the undercut, the smaller the area that the bumps can achieve, which can effectively reduce the metal line width and reduce the bump spacing to achieve more I / O and higher interconnection density. Therefore, when the over-etching (Over etch) is 100%, controlling the undercut within 1μm is to concretize the performance of the etching solution.

[0008] However, the problem of regulating the undercut distance when the over-etching is 100% has not been solved yet, and there is no systematic study on the impact of changes in the content of titanium etching solution components on etching performance. In addition, when other etching parameters remain unchanged, the faster the etching rate, the better, but there is generally no perfect choice that is both fast and accurate. In the process of process development, it is often necessary to balance parameters such as accuracy with rate. Summary of the invention

[0009] In view of the above technical problems, the present invention provides a titanium etching solution for wafer-level packaging and a preparation method and application thereof, wherein the titanium etching solution has the advantages of long service life, good titanium etching specificity, no corrosion to copper, and can effectively control the side wall etching rate and reduce the side corrosion effect.

[0010] In order to achieve the above-mentioned purpose, the present invention provides a titanium etching solution for wafer-level packaging. The titanium etching solution consists of a component A and a component B. The component A consists of the following raw materials accounting for the total mass percentage of the titanium etching solution: 2-20% of an inorganic base, 1-15% of an inorganic acid, 0.5-5% of a pH stabilizer, and the balance is water; the component B consists of the following raw materials accounting for the total mass percentage of the titanium etching solution: 4.5-30% of hydrogen peroxide, 0.1-0.5% of an organic phosphine compound, 0.01-0.1% of a surfactant, and the balance is water.

[0011] Preferably, the mass ratio of component A to component B is 1:1.

[0012] Preferably, the mass ratio of the inorganic base to the organic acid in the A component is 1.1-2:1.

[0013] Further preferably, the inorganic base is sodium hydroxide or potassium hydroxide.

[0014] More preferably, the inorganic acid is any one of phosphoric acid, nitric acid, hydrochloric acid, sulfuric acid and boric acid.

[0015] Preferably, the pH stabilizer is one or more of ammonia water, ethanolamine, sodium citrate, sodium bicarbonate, potassium bicarbonate, triethylamine, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, sodium carbonate, potassium carbonate, ammonium carbonate and ammonium bicarbonate.

[0016] Preferably, the organic phosphine compound is any one of dodecylphosphonic acid, tetradecylphosphonic acid and hexamethylenediaminetetramethylenephosphonic acid.

[0017] Preferably, the surfactant is any one of dodecyl dimethyl amine oxide, dodecyl dihydroxyethyl amine oxide, tetradecyl dimethyl amine oxide, tetradecyl dihydroxyethyl amine oxide, hexadecyl dimethyl amine oxide and hexadecyl dihydroxyethyl amine oxide.

[0018] The present invention also provides a method for preparing a titanium etching solution for wafer-level packaging, comprising the following steps: (1) Dissolve an inorganic acid and an inorganic base in water in turn, cool to room temperature, add a pH stabilizer, and mix well to obtain component A; (2) dissolving hydrogen peroxide, an organic phosphine compound and a surfactant in water in sequence and mixing them evenly to obtain a component B; (3) Slowly add component B into component A and mix them in equal amounts to obtain a titanium etching solution.

[0019] The present invention also provides an application of a titanium etching solution for wafer-level packaging, wherein the application is etching a wafer containing copper and titanium; wherein the thickness of the copper in the wafer is 400 nm, and the thickness of the titanium is 100 nm.

[0020] Preferably, the method for etching a wafer containing titanium is as follows: (1) Heat the titanium etching solution water bath to 25-55°C; (2) Soaking the wafer containing copper and titanium in a titanium etching solution for 1 to 10 minutes to obtain an etched wafer; (3) Rinse the etched wafer with ultrapure water, and then use nitrogen to blow away the water stains on the surface of the wafer to complete the etching.

[0021] The beneficial effects of the present invention are: 1. The titanium etching solution is divided into two components, A and B, to ensure that the titanium etching solution can be stored for a long time. The pH stabilizer in component A prevents the organic phosphine compounds from depositing or aggregating together by maintaining the stability and dispersibility of the charged particles in the system, thereby affecting the complexation with the metal, so that the titanium etching solution has good stability and uniformity; in addition, the surfactant and the pH stabilizer have a synergistic effect, further improving the storage stability and uniformity of the titanium etching solution.

[0022] 2. Under alkaline conditions, the above surfactant is non-ionic. Due to its long alkyl chain structure and properties, it can effectively reduce the surface tension of the solution, allowing the solution to better enter the narrow line width area (1~3μm) of the wafer, ensuring the uniformity of titanium. In addition, the carbon chain structure of alkylamine oxide and organic phosphorus is the same as that of alkylamine oxide N + The positive and negative ions between the phosphate group and the phosphate group attract each other, making the two have good compatibility, and the organic phosphorus can more easily enter the undercut part. - Mutual repulsion with phosphate can reduce the attraction between the two, which helps the organic phosphorus to react with the newly generated Ti 4+ Complexation and forming a protective film prevents the liquid from contacting the Ti metal and reduces side corrosion. At the same time, alkylamine oxide has a thickening effect, the viscosity of the liquid will increase, which will further increase the difficulty of the liquid entering the undercut part, which is conducive to reducing side corrosion.

[0023] 3. The titanium etching solution prepared by the present invention has the advantages of long service life, good titanium etching specificity, no corrosion to copper, effective control of side wall etching rate, and reduction of side corrosion, and can be widely applied and promoted. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further explained below in conjunction with specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The protection scope of the present invention shall be subject to the contents recorded in the claims. Any modification or replacement made by a person skilled in the art to the technical solution of the present invention without creative work shall fall within the protection scope of the present invention.

[0025] In the following examples and comparative examples, the concentration of hydrogen peroxide is 55%, the concentration of phosphoric acid is 89%, the concentration of potassium hydroxide is 48%, and both dodecyl dimethyl amine oxide and dodecyl phosphonic acid are analytically pure. In the examples and comparative examples, the mass percentage is calculated based on the solute of the corresponding solution, for example, the mass percentage of phosphoric acid is calculated based on the mass of the solute H3PO4.

[0026] Example 1 A titanium etching solution E1 is formulated as 50% of component A and 50% of component B in terms of mass percentage, wherein component A comprises 2% of potassium hydroxide, 1% of phosphoric acid, 1% of trisodium phosphate and 46% of water, accounting for the total mass percentage of the titanium etching solution; and component B comprises 4.5% of hydrogen peroxide, 0.1% of dodecylphosphonic acid, 0.01% of dodecyl dimethyl amine oxide and 45.39% of water, accounting for the total mass percentage of the titanium etching solution.

[0027] Preparation and etching method: (1) Component A and component B are prepared according to the formula, and then component B is slowly added to component A, and mixed in equal mass ratio to obtain titanium etching solution E1; wherein components A and B are ensured not to be splashed during mixing; (2) The titanium etching solution E1 is heated to 55° C. in a water bath, and then the titanium wafer is immersed in the etching solution for 3 minutes to obtain an etched wafer W1; (3) Rinse the etched wafer W1 with ultrapure water, and then use nitrogen to clean the water stains on the surface of W1, and the etching is completed; (4) Use energy spectrum (SEM-EDS) to observe the presence of titanium element after W1 etching, obtain the reaction endpoint time (EPD), and OE100%. Use focused ion beam electron microscopy (FIB-SEM) to observe undercut. The results are shown in Table 1.

[0028] Example 2 A titanium etching solution E2 has a formula of 50% of component A and 50% of component B in terms of mass percentage, wherein component A comprises 20% of potassium hydroxide, 15% of phosphoric acid, 5% of trisodium phosphate and 10% of water, accounting for the total mass percentage of the titanium etching solution, and component B comprises 30% of hydrogen peroxide, 0.5% of dodecylphosphonic acid, 0.1% of dodecyl dimethyl amine oxide and 19.4% of water, accounting for the total mass percentage of the titanium etching solution.

[0029] The preparation and etching methods are the same as those in Example 1, except that the temperature of the titanium etching solution E2 is adjusted to 25° C. to obtain an etched wafer W2.

[0030] Example 3 A titanium etching solution E3 is formulated as 50% of component A and 50% of component B in terms of mass percentage, wherein component A comprises 10% of potassium hydroxide, 5% of phosphoric acid, 1% of disodium hydrogen phosphate and 34% of water, accounting for the total mass percentage of the titanium etching solution, and component B comprises 15% of hydrogen peroxide, 0.25% of dodecylphosphonic acid, 0.05% of dodecyl dimethyl amine oxide and 34.7% of water, accounting for the total mass percentage of the titanium etching solution.

[0031] The preparation and etching methods are the same as those in Example 1, except that the temperature of the titanium etching solution E3 is adjusted to 35° C. to obtain an etched wafer W3.

[0032] Example 4 A titanium etching solution E4 is formulated as 50% of component A and 50% of component B in terms of mass percentage, wherein component A comprises 10% of potassium hydroxide, 5% of phosphoric acid, 1% of tripotassium phosphate and 34% of water, accounting for the total mass percentage of the titanium etching solution, and component B comprises 20% of hydrogen peroxide, 0.25% of dodecylphosphonic acid, 0.01% of dodecyl dimethylamine oxide and 29.74% of water, accounting for the total mass percentage of the titanium etching solution.

[0033] The preparation and etching methods are the same as those in Example 1, except that the temperature of the titanium etching solution E4 is adjusted to 25° C. to obtain an etched wafer W4.

[0034] Example 5 A titanium etching solution E5 is formulated as 50% of component A and 50% of component B in terms of mass percentage, wherein component A comprises 5% of potassium hydroxide, 3% of phosphoric acid, 1% of tripotassium phosphate and 41% of water, accounting for the total mass percentage of the titanium etching solution, and component B comprises 20% of hydrogen peroxide, 0.25% of dodecylphosphonic acid, 0.01% of dodecyl dimethylamine oxide and 29.74% of water, accounting for the total mass percentage of the titanium etching solution.

[0035] The preparation and etching methods are the same as those in Example 1, except that the temperature of the titanium etching solution E5 is adjusted to 45° C. to obtain an etched wafer W5.

[0036] Example 6 A titanium etching solution E6 has a formula of 50% of component A and 50% of component B in terms of mass percentage, wherein component A comprises 10% of potassium hydroxide, 5% of phosphoric acid, 1% of tripotassium phosphate and 34% of water, accounting for the total mass percentage of the titanium etching solution; and component B comprises 10% of hydrogen peroxide, 0.2% of dodecylphosphonic acid, 0.01% of dodecyl dimethylamine oxide and 39.79% of water, accounting for the total mass percentage of the titanium etching solution.

[0037] The preparation and etching methods are the same as those in Example 1, except that the temperature of the titanium etching solution E6 is adjusted to 25° C. to obtain an etched wafer W6.

[0038] Example 7 A titanium etching solution E7 is formulated as 50% of component A and 50% of component B in terms of mass percentage, wherein component A comprises 10% of potassium hydroxide, 5% of nitric acid, 1% of triethylamine and 34% of water, accounting for the total mass percentage of the titanium etching solution, and component B comprises 10% of hydrogen peroxide, 0.2% of tetradecylphosphonic acid, 0.01% of dodecyl dihydroxyethyl amine oxide and 39.79% of water, accounting for the total mass percentage of the titanium etching solution.

[0039] The preparation and etching methods are the same as those in Example 1, except that the temperature of the titanium etching solution E7 is adjusted to 25° C. to obtain an etched wafer W7.

[0040] Example 8 A titanium etching solution E8 is formulated as 50% of component A and 50% of component B in terms of mass percentage, wherein component A comprises 10% of potassium hydroxide, 5% of hydrochloric acid, 1% of ammonium bicarbonate and 34% of water, accounting for the total mass percentage of the titanium etching solution, and component B comprises 10% of hydrogen peroxide, 0.2% of hexamethylenediaminetetramethylenephosphonic acid, 0.01% of tetradecyldimethylamine oxide and 39.79% of water, accounting for the total mass percentage of the titanium etching solution.

[0041] The preparation and etching methods are the same as those in Example 1, except that the temperature of the titanium etching solution E8 is adjusted to 25° C. to obtain an etched wafer W8.

[0042] Example 9 A titanium etching solution E9 is formulated as 50% of component A and 50% of component B in terms of mass percentage, wherein component A comprises 10% of potassium hydroxide, 5% of boric acid, 1% of sodium carbonate and 34% of water, accounting for the total mass percentage of the titanium etching solution, and component B comprises 10% of hydrogen peroxide, 0.2% of tetradecylphosphonic acid, 0.01% of tetradecyl dihydroxyethyl amine oxide and 39.79% of water, accounting for the total mass percentage of the titanium etching solution.

[0043] The preparation and etching methods are the same as those in Example 1, except that the temperature of the titanium etching solution E9 is adjusted to 25° C. to obtain an etched wafer W9.

[0044] Example 10 A titanium etching solution E10 is formulated as 50% of component A and 50% of component B in terms of mass percentage, wherein component A comprises 10% of potassium hydroxide, 5% of sulfuric acid, 1% of ammonia water and 34% of water, accounting for the total mass percentage of the titanium etching solution, and component B comprises 10% of hydrogen peroxide, 0.2% of dodecylphosphonic acid, 0.01% of hexadecyl dimethylamine oxide and 39.79% of water, accounting for the total mass percentage of the titanium etching solution.

[0045] The preparation and etching methods are the same as those in Example 1, except that the temperature of the titanium etching solution E10 is adjusted to 25° C. to obtain an etched wafer W10.

[0046] Comparative Example 1 A titanium etching solution E11 has the same formula as in Example 6, wherein component B does not contain 0.01% dodecyl dimethyl amine oxide, and the preparation and etching methods are the same as in Example 6, to obtain an etched wafer W11.

[0047] Comparative Example 2 A titanium etching solution E12 has the same formula as Example 6, wherein component A does not contain 1% tripotassium phosphate, and the preparation and etching methods are the same as Example 6 to obtain an etched wafer W12.

[0048] Comparative Example 3 A titanium etching solution E13 has the same formula as in Example 6, wherein component B does not contain 0.2% dodecylphosphonic acid, and the preparation and etching methods are the same as in Example 6, to obtain an etched wafer W13.

[0049] Comparative Example 4 A titanium etching solution E14 has the same formula as Example 6, wherein component A does not contain 1% tripotassium phosphate, and component B does not contain 0.2% dodecylphosphonic acid and 0.01% dodecyl dimethylamine oxide. The preparation and etching methods are the same as Example 1 to obtain an etched wafer W14.

[0050] Comparative Example 5 A titanium etching solution E15 has the same formula as Example 6, wherein the content of tripotassium phosphate in component A is changed from 1% to 0.1%, and the preparation and etching methods are the same as Example 1, to obtain an etched wafer W15.

[0051] Comparative Example 6 A titanium etching solution E16 has the same formula as Example 6, wherein the content of tripotassium phosphate in component A is changed from 1% to 6%. The preparation and etching methods are the same as Example 1, and an etched wafer W16 is obtained.

[0052] Comparative Example 7 A titanium etching solution E17 has the same formula as Example 6, wherein the content of dodecylphosphonic acid in component B is changed from 0.2% to 0.05%, and the preparation and etching methods are the same as Example 1, to obtain an etched wafer W17.

[0053] Comparative Example 8 A titanium etching solution E18 has the same formula as Example 6, wherein the content of dodecylphosphonic acid in component B is changed from 0.2% to 1%, and the preparation and etching methods are the same as Example 1 to obtain an etched wafer W18.

[0054] Comparative Example 9 A titanium etching solution E19 has the same formula as Example 6, wherein the content of dodecyl dimethyl amine oxide in component B is changed from 0.1% to 0.5%, and the preparation and etching methods are the same as Example 1 to obtain an etched wafer W19.

[0055] Comparative Example 10 A titanium etching solution E20 has the same formula as Example 6, wherein the dodecyl dimethyl amine oxide in component B is replaced with an equal amount of dodecyl polyoxyethylene ether, and the preparation and etching methods are the same as Example 1 to obtain an etched wafer W20.

[0056] Comparative Example 11 A titanium etching solution E21 has the same formula as Example 6, and the same preparation and etching methods as Example 1, wherein the temperature of the titanium etching solution is changed to 20° C. to obtain an etched wafer W21.

[0057] Comparative Example 12 A titanium etching solution E22 has the same formula as Example 6, and the same preparation and etching methods as Example 1, wherein the temperature of the titanium etching solution is changed to 60° C. to obtain an etched wafer W22.

[0058] Table 1 Titanium etching solution properties

[0059] The results show that the service life of Examples 1 to 10 can reach 720h. Different combinations of inorganic acid, inorganic base, surfactant, organic phosphine and pH stabilizer in the etching solution have an impact on the etching rate and undercut, but have little impact on the etching life. Within the limited temperature, the decomposition rate of hydrogen peroxide is slow, which makes the etching rate stable and the service life longer. In Comparative Examples 1 to 4, the lack of any one of the surfactant, organic phosphine and pH stabilizer will cause the undercut to exceed 1μm, and the life will be sharply shortened. pH stabilizer, the absence will affect the stability and dispersibility of the charged particles of the liquid, the organic phosphine compounds will deposit or aggregate together, and the increase in the complexation test with the metal will be reduced; the lack of surfactant will make it more difficult for the liquid to enter the narrow line width part, resulting in titanium residue after etching, and the organic phosphine will not easily enter the undercut part, and the side etching will increase; the lack of organic phosphine will directly cause the side etching to become larger. In Comparative Examples 5 to 12, the amount of surfactant, organic phosphine and pH stabilizer is not within the range, resulting in a significant deterioration in the service life, among which when dodecyl dimethyl amine oxide is replaced, the undercut exceeds 1μm. Temperature changes will affect the service life and undercut.

Claims

1. A titanium etching solution for wafer-level packaging, characterized in that: The titanium etching solution consists of component A and component B, wherein the component A consists of the following raw materials accounting for the total mass percentage of the titanium etching solution: 2-20% of inorganic base, 1-15% of inorganic acid, 0.5-5% of pH stabilizer, and the balance is water; the component B consists of the following raw materials accounting for the total mass percentage of the titanium etching solution: 4.5-30% of hydrogen peroxide, 0.1-0.5% of organic phosphine compound, 0.01-0.1% of surfactant, and the balance is water.

2. The titanium etching solution for wafer-level packaging according to claim 1, characterized in that: The mass ratio of the A component to the B component is 1:

1.

3. The titanium etching solution for wafer-level packaging according to claim 1, characterized in that: The mass ratio of the inorganic base to the organic acid in the A component is 1.1-2:

1.

4. The titanium etching solution for wafer-level packaging according to claim 3, characterized in that: The inorganic base is sodium hydroxide or potassium hydroxide.

5. The titanium etching solution for wafer-level packaging according to claim 3, characterized in that: The inorganic acid is any one of phosphoric acid, nitric acid, hydrochloric acid, sulfuric acid and boric acid.

6. The titanium etching solution for wafer-level packaging according to claim 1, characterized in that: The pH stabilizer is one or more of ammonia water, ethanolamine, sodium citrate, sodium bicarbonate, potassium bicarbonate, triethylamine, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, sodium carbonate, potassium carbonate, ammonium carbonate and ammonium bicarbonate.

7. The titanium etching solution for wafer-level packaging according to claim 1, characterized in that: The organic phosphine compound is any one of dodecylphosphonic acid, tetradecylphosphonic acid and hexamethylenediaminetetramethylenephosphonic acid.

8. The titanium etching solution for wafer-level packaging according to claim 1, characterized in that: The surfactant is any one of dodecyl dimethyl amine oxide, dodecyl dihydroxyethyl amine oxide, tetradecyl dimethyl amine oxide, tetradecyl dihydroxyethyl amine oxide, hexadecyl dimethyl amine oxide and hexadecyl dihydroxyethyl amine oxide.

9. A method for preparing a titanium etching solution for wafer-level packaging according to any one of claims 1 to 8, characterized in that: The steps include: (1) Dissolve an inorganic acid and an inorganic base in water in turn, cool to room temperature, add a pH stabilizer, and mix well to obtain component A; (2) dissolving hydrogen peroxide, an organic phosphine compound and a surfactant in water in sequence and mixing them evenly to obtain a component B; (3) Slowly add component B into component A and mix them in equal amounts to obtain a titanium etching solution.

10. An application of the titanium etching solution for wafer-level packaging according to any one of claims 1 to 8, characterized in that: The application is etching of wafers containing copper and titanium.

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