Titanium-aluminum alloy etching solution and preparation method thereof

Abstract

The invention provides a titanium-aluminum alloy etching solution and a preparation method thereof, and the titanium-aluminum alloy etching solution comprises the following components in percentage by mass: 10-20% of hydrogen peroxide, 0.1-1% of hydrogen peroxide stabilizer, 0.5-2% of inorganic acid, 3-6% of alkali, 0.1-2% of inhibitor and the balance of deionized water. The etching solution can protect a metal Al layer from being corroded while etching a TiAl alloy. The preparation method of the etching solution comprises the step of sequentially adding deionized water, hydrogen peroxide, a hydrogen peroxide stabilizer, inorganic acid, alkali and an inhibitor into a mixing kettle.

Description

Technical Field

[0001] The invention belongs to the field of electronic chemicals and relates to a metal etching liquid, in particular to a titanium aluminum (TiAl) alloy etching liquid and a preparation method thereof. Background Art

[0002] The composite structure of TiAl alloy is resistant to high temperature, corrosion and has excellent electrical and thermal conductivity, making it an indispensable material for manufacturing electrodes, seed layers, buffer layers and heat dissipation layers in semiconductor devices.

[0003] Metal aluminum (Al) plays a vital role in the field of semiconductor manufacturing. It is often used as a metallization layer to form electrical connections and interconnects, forming ohmic contacts with semiconductor materials to reduce contact resistance while also improving device stability. It is an indispensable key material in the semiconductor device manufacturing process.

[0004] In the semiconductor field, when TiAl alloy film and Al layer are stacked in a structure, they are mainly used in specific occasions that require high-temperature strength, good electrical and thermal conductivity, and corrosion resistance of the material, such as microelectronic packaging, thermal protection materials, and interconnection structures in high-temperature environments. This structure can combine the respective advantages of TiAl alloy and Al layer to meet the high-performance requirements of semiconductor devices in complex working environments.

[0005] However, in the wet etching process, the corrosion rate of TiAl alloy is significantly lower than that of Al layer, which often causes serious side etching of Al layer when etching TiAl layer, thus posing a severe challenge to the stability and reliability of the device. In order to solve this problem, we proposed a solution of adding a specific Al corrosion inhibitor to the TiAl etching solution, aiming to achieve a dual purpose: on the one hand, to minimize the impact on the etching rate of TiAl layer; on the other hand, to significantly slow down the etching rate of metal Al, ensuring that the selectivity ratio of TiAl / Al etching rate meets the manufacturing standards, thereby comprehensively improving the stability and reliability of the entire process. Summary of the invention

[0006] In order to solve the technical problems in the background technology, the present invention provides a titanium aluminum alloy etching solution and a method for preparing the etching solution. The specific technical solutions provided are as follows: The invention provides a TiAl etching solution, wherein the TiAl etching solution has a hydrogen peroxide content of 10-20%, a hydrogen peroxide stabilizer content of 0.1-1%, an inorganic acid content of 0.5-2%, an alkali content of 3-6%, an inhibitor content of 0.1-2%, and the balance is deionized water.

[0007] Preferably, the TiAl etching solution contains 14-16% hydrogen peroxide, 0.1-0.5% hydrogen peroxide stabilizer, 0.5-1% inorganic acid, 2-4% alkali, 0.1-1% inhibitor, and the balance is deionized water.

[0008] Preferably, the hydrogen peroxide stabilizer is a combination of at least one or more of citric acid, p-aminobenzenesulfonic acid, para-hydroxybenzoate, isopropyl alcohol or polyvinyl pyrrolidone; further preferably, the hydrogen peroxide stabilizer is a combination of at least one or more of citric acid, p-aminobenzenesulfonic acid or polyvinyl pyrrolidone.

[0009] Preferably, the inorganic acid is a combination of at least one or more of phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid; further preferably, the inorganic acid is a combination of at least one or more of phosphoric acid, sulfuric acid or nitric acid.

[0010] Preferably, the base is a combination of at least one or more of ammonia water, potassium hydroxide, sodium hydroxide or tetramethylammonium hydroxide; further preferably, the base is a combination of at least one or more of potassium hydroxide, sodium hydroxide or tetramethylammonium hydroxide.

[0011] Preferably, the inhibitor comprises at least one of ethylenediaminetetraacetic acid, dimethyl methylphosphonate, polyacrylic acid, polyaspartic acid, thioglycolic acid, benzotriazole, 2-methylimidazole, 4-phenyl-1H-imidazole, 2-(4-fluorophenyl)-4,5-dihydroimidazole, 1,2,3-triazol-1-ylmethylimidazole or 2-(2-hydroxyethyl)-4,5-dihydroimidazole.

[0012] Preferably, the inhibitor is a combination of inhibitor A and inhibitor B; inhibitor A is one of ethylenediaminetetraacetic acid, dimethyl methylphosphonate, polyacrylic acid, polyaspartic acid or thioglycolic acid, and inhibitor B is one of benzotriazole, 2-methylimidazole, 4-phenyl-1H-imidazole, 2-(4-fluorophenyl)-4,5-dihydroimidazole, 1,2,3-triazol-1-ylmethylimidazole or 2-(2-hydroxyethyl)-4,5-dihydroimidazole.

[0013] Preferably, the mass ratio of the inhibitor A to the inhibitor B is 1:2-2:1; further preferably, the mass ratio of the inhibitor A to the inhibitor B is 1:1.

[0014] The present invention provides a method for preparing the TiAl etching solution, which comprises the following steps: adding hydrogen peroxide, a hydrogen peroxide stabilizer, an inorganic acid, an alkali and an inhibitor into deionized water in sequence, mixing and stirring to obtain the TiAl etching solution.

[0015] The beneficial effects of the present invention are as follows: (1) The present invention solves the problem of violent decomposition of hydrogen peroxide by selecting a suitable hydrogen peroxide stabilizer and further optimizing the concentration of hydrogen peroxide, so that the etching solution can ensure the etching rate in a safe and stable manner, thereby improving the production capacity.

[0016] (2) The present invention provides a two-component compound inhibitor, which can rapidly etch the TiAl alloy while inhibiting the etching of the Al layer, thereby improving the etching rate selectivity of the TiAl alloy layer and the Al layer. DETAILED DESCRIPTION

[0017] The embodiments of the present invention will be described in detail below with reference to examples. The following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0018] Example 1 A titanium aluminum alloy etching solution, wherein the mass content of hydrogen peroxide is 14%, the mass content of p-aminobenzenesulfonic acid is 0.2%, the mass content of phosphoric acid is 0.5%, the mass content of potassium hydroxide is 2%, the mass content of ethylenediaminetetraacetic acid is 0.5%, the mass content of benzotriazole is 0.5%, and the balance is deionized water. Hydrogen peroxide, a hydrogen peroxide stabilizer, an inorganic acid, an alkali, and an inhibitor are sequentially added into the deionized water and mixed and stirred to obtain an etching solution.

[0019] The TiAl monolith on the silicon substrate was etched at 60°C using the etching solution configured in the above ratio, and the TiAl monolith was cut into regular squares of 2cm*2cm in size. The thickness of the TiAl film layer was obtained by four-probe test. The four-probe selected four fixed center points of the metal film for testing and calculated the average of the thickness of the four points. The average is the thickness of the metal sheet, and the TiAl monolith etching rate can be calculated. The metal Al monolith etching rate can be obtained by the same operation method. The results are shown in Table 4.

[0020] For a better understanding of the invention, the formulation ratios of different embodiments and comparative examples are shown in a table.

[0021] Table 1: Formula ratio of Examples 1-10

[0022] Table 2: Formula ratio of Examples 11-20

[0023] Table 3 Formula ratio of Examples 21-25 and Comparative Examples 1-3

[0024] Table 4 Data and selectivity of etching experiments of Examples 1 to 25 and Comparative Examples 1 to 3

[0025] It can be seen from the above data that by selecting appropriate inhibitors and regulating the pH of the system, the TiAl / Al etching ratio can be significantly improved without affecting the TiAl etching rate as much as possible; in addition, when two inhibitors are used in combination, it is more conducive to adjusting the TiAl / Al etching rate.

[0026] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A titanium aluminum alloy etching solution, characterized in that: By mass fraction, it includes the following components: Hydrogen peroxide 10-20%, hydrogen peroxide stabilizer 0.1-1%, inorganic acid 0.5-2%, alkali 3-6%, inhibitor 0.1-2%, and the balance is deionized water.

2. The titanium-aluminum alloy etching solution according to claim 1, characterized in that: The composition comprises the following components by mass fraction: 14-16% hydrogen peroxide, 0.1-0.5% hydrogen peroxide stabilizer, 0.5-1% inorganic acid, 2-4% alkali, 0.1-1% inhibitor, and the balance is deionized water.

3. The titanium-aluminum alloy etching solution according to claim 1, characterized in that: The hydrogen peroxide stabilizer is a combination of at least one or more of citric acid, p-aminobenzenesulfonic acid, p-hydroxybenzoate, isopropyl alcohol or polyvinyl pyrrolidone.

4. The titanium-aluminum alloy etching solution according to claim 1, characterized in that: The inorganic acid is a combination of at least one or more of phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid.

5. The titanium-aluminum alloy etching solution according to claim 1, characterized in that: The alkali is a combination of at least one or more of ammonia water, potassium hydroxide, sodium hydroxide or tetramethylammonium hydroxide.

6. The titanium-aluminum alloy etching solution according to claim 1, characterized in that: The inhibitor includes at least one of ethylenediaminetetraacetic acid, dimethyl methylphosphonate, polyacrylic acid, polyaspartic acid, thioglycolic acid, benzotriazole, 2-methylimidazole, 4-phenyl-1H-imidazole, 2-(4-fluorophenyl)-4,5-dihydroimidazole, 1,2,3-triazol-1-ylmethylimidazole or 2-(2-hydroxyethyl)-4,5-dihydroimidazole.

7. The titanium-aluminum alloy etching solution according to claim 1, characterized in that: The inhibitor is a combination of inhibitor A and inhibitor B; inhibitor A is one of ethylenediaminetetraacetic acid, dimethyl methylphosphonate, polyacrylic acid, polyaspartic acid or thioglycolic acid, and inhibitor B is one of benzotriazole, 2-methylimidazole, 4-phenyl-1H-imidazole, 2-(4-fluorophenyl)-4,5-dihydroimidazole, 1,2,3-triazol-1-ylmethylimidazole or 2-(2-hydroxyethyl)-4,5-dihydroimidazole.

8. The titanium-aluminum alloy etching solution according to claim 7, characterized in that: The mass ratio of the inhibitor A to the inhibitor B is 1:2-2:

1.

9. The method for preparing the titanium-aluminum alloy etching solution according to any one of claims 1 to 8, characterized in that: Hydrogen peroxide, a hydrogen peroxide stabilizer, an inorganic acid, an alkali and an inhibitor are sequentially added into deionized water, and the mixture is mixed and stirred to obtain a titanium-aluminum alloy etching solution.

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