Titanium tungsten etching solution for integrated circuit and preparation method thereof

Abstract

The application provides a titanium-tungsten etching solution for integrated circuits and a preparation method thereof, and belongs to the technical field of integrated circuits, and is prepared from the following raw materials according to weight parts: 5-10 parts of nitric acid, 3-7 parts of sulfuric acid, 15-20 parts of phosphoric acid, 3-5 parts of a polydopamine-chitosan complex stabilizer, 1-2 parts of a surfactant and 40-50 parts of water. The titanium-tungsten etching solution for integrated circuits can effectively etch a titanium-tungsten alloy, effectively decomposes a metal layer on the surface of the titanium-tungsten alloy, improves etching efficiency, and is uniform, thorough, stable in performance, long in service life, easy to wash and free of residues after etching.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and more specifically to a titanium-tungsten etching solution for integrated circuits and its preparation method. Background Technology

[0002] As chip feature sizes shrink further, the pitch of input / output terminals on chips is moving towards dimensions below 100 micrometers (even down to 40 micrometers). This poses a significant challenge to the manufacturing of bump structures on flip-chip packages. In the bump structure manufacturing process, photolithography and electroplating are the industry standard choices for obtaining accurate bump dimensions. The electroplating of copper bump structures requires a metal seed layer for conductivity. Since chip surface electrodes are typically made of aluminum (or aluminum-copper, aluminum-silicon), from a materials science perspective, to prevent the interdiffusion of aluminum and copper, a metal layer needs to be deposited on the aluminum electrode surface to block interdiffusion and ensure good bonding between the metals. This metal layer is known in the industry as a barrier layer, and is usually made of titanium-tungsten alloy, often formed using physical vapor deposition. Wet etching is typically used to remove ineffective titanium or titanium-tungsten alloys. Hydrogen peroxide decomposes readily in the presence of copper ions, therefore, copper ion complexing agents and hydrogen peroxide stabilizers need to be added. Uneven corrosion occurs due to the minute gaps on the surface of the titanium layer. Therefore, surfactants are added to the system to reduce the surface tension of the etching solution, allowing it to penetrate into these tiny gaps and improve the corrosion effect. The titanium-tungsten etching solution composition can be used for the selective corrosion of titanium-tungsten alloys in the presence of at least one of copper, tin, tin alloys, and aluminum.

[0003] In addition, existing etching solutions have the defect of not being able to rinse completely, and the residual etching solution may cause further corrosion to the chip. Therefore, further improving the existing etching solution and increasing its ease of rinsing is also a technical problem that needs to be considered by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a titanium-tungsten etchant for integrated circuits and its preparation method, which can effectively etch titanium-tungsten alloys, effectively decompose the metal layer on the surface of titanium-tungsten, improve etching efficiency, and provide uniform and thorough corrosion of the metal layer with stable performance, long service life, and easy rinsing of residual liquid after etching without residue.

[0005] The technical solution of this invention is implemented as follows:

[0006] This invention provides a titanium-tungsten etching solution for integrated circuits, comprising the following raw materials: nitric acid, sulfuric acid, phosphoric acid, polydopamine-chitosan complex stabilizer, surfactant, and water.

[0007] As a further improvement of the present invention, it is prepared from the following raw materials in parts by weight: 5-10 parts nitric acid, 3-7 parts sulfuric acid, 15-20 parts phosphoric acid, 3-5 parts polydopamine-chitosan complex stabilizer, 1-2 parts surfactant, and 40-50 parts water.

[0008] As a further improvement of the present invention, the sulfuric acid is concentrated sulfuric acid with a concentration greater than 98%.

[0009] As a further improvement of the present invention, the surfactant is selected from at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfonate, sodium dodecyl sulfate, sodium tetradecyl sulfonate, sodium tetradecylbenzenesulfonate, sodium hexadecylbenzenesulfonate, sodium hexadecyl sulfonate, sodium hexadecyl sulfate, sodium octadecyl sulfonate, sodium octadecylbenzenesulfonate, and sodium octadecyl sulfate.

[0010] As a further improvement of the present invention, the preparation method of the polydopamine-chitosan complex stabilizer is as follows:

[0011] S1. Dissolve chitosan in acetic acid solution to obtain chitosan solution;

[0012] S2. Add dopamine hydrochloride and catalyst to the chitosan solution obtained in step S1, heat and stir to react, and obtain polydopamine-chitosan copolymer;

[0013] S3. Add the polydopamine-chitosan copolymer obtained in step S2 to hydrochloric acid, stir and react to obtain the polydopamine-chitosan complex stabilizer.

[0014] As a further improvement of the present invention, the concentration of the acetic acid solution in step S1 is 3-5 wt%; the concentration of chitosan in the chitosan solution is 5-12 wt%.

[0015] As a further improvement of the present invention, the mass ratio of chitosan solution, dopamine hydrochloride and catalyst in step S2 is 100:15-20:2-3; the catalyst is a Tris-HCl solution with a pH of 5-6; the heating and stirring reaction is carried out at a temperature of 50-60°C for 1-2 hours.

[0016] As a further improvement of the present invention, the concentration of hydrochloric acid in step S3 is 2-4 mol / L; and the stirring reaction time is 30-50 min.

[0017] As a further improvement of the present invention, the preparation method of the polydopamine-chitosan complex stabilizer is as follows:

[0018] S1. Dissolve chitosan in a 3-5 wt% acetic acid solution to obtain a 5-12 wt% chitosan solution;

[0019] S2. Add 15-20 parts by weight of dopamine hydrochloride and 2-3 parts by weight of catalyst to 100 parts by weight of chitosan solution obtained in step S1, heat to 50-60℃, stir and react for 1-2 hours to obtain polydopamine-chitosan copolymer.

[0020] The catalyst is a Tris-HCl solution with a pH of 5-6;

[0021] S3. Add the polydopamine-chitosan copolymer obtained in step S2 to 2-4 mol / L hydrochloric acid and stir for 30-50 min to obtain the polydopamine-chitosan complex stabilizer.

[0022] The present invention further protects a method for preparing the above-mentioned titanium-tungsten etching solution for integrated circuits, comprising the following steps: stirring and mixing nitric acid, sulfuric acid, phosphoric acid, surfactant and water evenly, adding polydopamine complexing stabilizer, stirring and mixing to obtain the titanium-tungsten etching solution for integrated circuits.

[0023] The present invention has the following beneficial effects: In the present invention, nitric acid, sulfuric acid and phosphoric acid are mixed in appropriate proportions, which can effectively etch titanium-tungsten alloy, effectively decompose the metal layer on the surface of titanium-tungsten, improve etching efficiency, and make the metal layer corrosion uniform and thorough, with stable performance and long service life. The residual liquid after etching is easy to rinse and leaves no residue.

[0024] This invention prepares a polydopamine-chitosan complex stabilizer. Based on the formation of a chitosan-polydopamine copolymer, it further reacts with hydrochloric acid to form a cationic "chelating hand," thereby promoting the complexation of titanium and tungsten ions during acid etching, promoting the forward etching reaction, and thus accelerating the etching rate. In addition, the high molecular copolymer structure can also stabilize the acid, resulting in a longer service life and more stable performance of the etching solution. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0026] Raw material composition (parts by weight): 5 parts nitric acid, 3 parts 98% concentrated sulfuric acid, 15 parts phosphoric acid, 3 parts polydopamine-chitosan complex stabilizer, 1 part sodium octadecyl sulfate, and 40 parts water.

[0027] The specific preparation method of the polydopamine-chitosan complex stabilizer is as follows:

[0028] S1. Dissolve chitosan in a 3 wt% acetic acid solution to obtain a 5 wt% chitosan solution;

[0029] S2. Add 15 parts by weight of dopamine hydrochloride and 2 parts by weight of catalyst to 100 parts by weight of chitosan solution obtained in step S1, heat to 50°C, stir and react for 1 hour to obtain polydopamine-chitosan copolymer.

[0030] The catalyst is a Tris-HCl solution with a pH of 5;

[0031] S3. Add the polydopamine-chitosan copolymer obtained in step S2 to 2 mol / L hydrochloric acid and stir for 30 min to obtain the polydopamine-chitosan complex stabilizer.

[0032] A method for preparing a titanium-tungsten etching solution for integrated circuits includes the following steps: stirring and mixing nitric acid, 98% concentrated sulfuric acid, phosphoric acid, sodium octadecyl sulfate and water until homogeneous, adding polydopamine complexing stabilizer, stirring and mixing to obtain the titanium-tungsten etching solution for integrated circuits. Example 2

[0033] Raw material composition (parts by weight): 10 parts nitric acid, 7 parts 98% concentrated sulfuric acid, 20 parts phosphoric acid, 5 parts polydopamine-chitosan complex stabilizer, 2 parts sodium hexadecyl sulfate, and 50 parts water.

[0034] The specific preparation method of the polydopamine-chitosan complex stabilizer is as follows:

[0035] S1. Dissolve chitosan in a 5 wt% acetic acid solution to obtain a 12 wt% chitosan solution;

[0036] S2. Add 20 parts by weight of dopamine hydrochloride and 3 parts by weight of catalyst to 100 parts by weight of chitosan solution obtained in step S1, heat to 60°C, stir and react for 2 hours to obtain polydopamine-chitosan copolymer.

[0037] The catalyst is a Tris-HCl solution with a pH of 6;

[0038] S3. Add the polydopamine-chitosan copolymer obtained in step S2 to 4 mol / L hydrochloric acid and stir for 50 min to obtain the polydopamine-chitosan complex stabilizer.

[0039] A method for preparing a titanium-tungsten etching solution for integrated circuits includes the following steps: stirring and mixing nitric acid, 98% concentrated sulfuric acid, phosphoric acid, sodium hexadecyl sulfate and water until homogeneous, adding polydopamine complexing stabilizer, stirring and mixing to obtain the titanium-tungsten etching solution for integrated circuits. Example 3

[0040] Raw material composition (parts by weight): 7 parts nitric acid, 5 parts 98% concentrated sulfuric acid, 17 parts phosphoric acid, 4 parts polydopamine-chitosan complex stabilizer, 1.5 parts sodium dodecylbenzenesulfonate, and 45 parts water.

[0041] The specific preparation method of the polydopamine-chitosan complex stabilizer is as follows:

[0042] S1. Dissolve chitosan in a 4 wt% acetic acid solution to obtain an 8 wt% chitosan solution;

[0043] S2. Add 17 parts by weight of dopamine hydrochloride and 2.5 parts by weight of catalyst to 100 parts by weight of chitosan solution obtained in step S1, heat to 55°C, stir and react for 1.5 h to obtain polydopamine-chitosan copolymer.

[0044] The catalyst is a Tris-HCl solution with a pH of 5.5;

[0045] S3. Add the polydopamine-chitosan copolymer obtained in step S2 to 3 mol / L hydrochloric acid and stir for 40 min to obtain the polydopamine-chitosan complex stabilizer.

[0046] A method for preparing a titanium-tungsten etching solution for integrated circuits includes the following steps: stirring and mixing nitric acid, 98% concentrated sulfuric acid, phosphoric acid, sodium dodecylbenzenesulfonate and water until homogeneous, adding polydopamine complexing stabilizer, stirring and mixing to obtain the titanium-tungsten etching solution for integrated circuits.

[0047] Comparative Example 1

[0048] The difference compared to Example 3 is that chitosan was not added.

[0049] Raw material composition (parts by weight): 7 parts nitric acid, 5 parts 98% concentrated sulfuric acid, 17 parts phosphoric acid, 4 parts polydopamine-chitosan complex stabilizer, 1.5 parts sodium dodecylbenzenesulfonate, and 45 parts water.

[0050] The specific preparation method of the polydopamine-chitosan complex stabilizer is as follows:

[0051] S1. Add 17 parts by weight of dopamine hydrochloride and 2.5 parts by weight of catalyst to 100 parts by weight of water, heat to 55°C, and stir for 1.5 h to obtain polydopamine;

[0052] The catalyst is a Tris-HCl solution with a pH of 5.5;

[0053] S2. Add the polydopamine obtained in step S2 to 3 mol / L hydrochloric acid and stir for 40 min to obtain polydopamine complex stabilizer.

[0054] A method for preparing a titanium-tungsten etching solution for integrated circuits includes the following steps: stirring and mixing nitric acid, 98% concentrated sulfuric acid, phosphoric acid, sodium dodecylbenzenesulfonate and water until homogeneous, adding polydopamine complexing stabilizer, stirring and mixing to obtain the titanium-tungsten etching solution for integrated circuits.

[0055] Comparative Example 2

[0056] The difference compared to Example 3 is that no dopamine hydrochloride and catalyst were added.

[0057] Raw material composition (parts by weight): 7 parts nitric acid, 5 parts 98% concentrated sulfuric acid, 17 parts phosphoric acid, 4 parts polydopamine-chitosan complex stabilizer, 1.5 parts sodium dodecylbenzenesulfonate, and 45 parts water.

[0058] The specific preparation method of the polydopamine-chitosan complex stabilizer is as follows:

[0059] S1. Dissolve chitosan in a 4 wt% acetic acid solution to obtain an 8 wt% chitosan solution;

[0060] S2. Add the chitosan solution obtained in step S1 to 3 mol / L hydrochloric acid and stir for 40 min to obtain polydopamine-chitosan complex stabilizer.

[0061] A method for preparing a titanium-tungsten etching solution for integrated circuits includes the following steps: stirring and mixing nitric acid, 98% concentrated sulfuric acid, phosphoric acid, sodium dodecylbenzenesulfonate and water until homogeneous, adding polydopamine complexing stabilizer, stirring and mixing to obtain the titanium-tungsten etching solution for integrated circuits.

[0062] Comparative Example 3

[0063] The difference compared to Example 3 is that nitric acid was not added.

[0064] Raw material composition (parts by weight): 5 parts of 98% concentrated sulfuric acid, 24 parts of phosphoric acid, 4 parts of polydopamine-chitosan complex stabilizer, 1.5 parts of sodium dodecylbenzenesulfonate, and 45 parts of water.

[0065] The specific preparation method of the polydopamine-chitosan complex stabilizer is as follows:

[0066] S1. Dissolve chitosan in a 4 wt% acetic acid solution to obtain an 8 wt% chitosan solution;

[0067] S2. Add 17 parts by weight of dopamine hydrochloride and 2.5 parts by weight of catalyst to 100 parts by weight of chitosan solution obtained in step S1, heat to 55°C, stir and react for 1.5 h to obtain polydopamine-chitosan copolymer.

[0068] The catalyst is a Tris-HCl solution with a pH of 5.5;

[0069] S3. Add the polydopamine-chitosan copolymer obtained in step S2 to 3 mol / L hydrochloric acid and stir for 40 min to obtain the polydopamine-chitosan complex stabilizer.

[0070] A method for preparing a titanium-tungsten etching solution for integrated circuits includes the following steps: mixing 98% concentrated sulfuric acid, phosphoric acid, sodium dodecylbenzenesulfonate and water evenly, adding polydopamine complexing stabilizer, and mixing to obtain the titanium-tungsten etching solution for integrated circuits.

[0071] Comparative Example 4

[0072] The difference compared to Example 3 is that phosphoric acid was not added.

[0073] Raw material composition (parts by weight): 24 parts nitric acid, 5 parts 98% concentrated sulfuric acid, 4 parts polydopamine-chitosan complex stabilizer, 1.5 parts sodium dodecylbenzenesulfonate, and 45 parts water.

[0074] The specific preparation method of the polydopamine-chitosan complex stabilizer is as follows:

[0075] S1. Dissolve chitosan in a 4 wt% acetic acid solution to obtain an 8 wt% chitosan solution;

[0076] S2. Add 17 parts by weight of dopamine hydrochloride and 2.5 parts by weight of catalyst to 100 parts by weight of chitosan solution obtained in step S1, heat to 55°C, stir and react for 1.5 h to obtain polydopamine-chitosan copolymer.

[0077] The catalyst is a Tris-HCl solution with a pH of 5.5;

[0078] S3. Add the polydopamine-chitosan copolymer obtained in step S2 to 3 mol / L hydrochloric acid and stir for 40 min to obtain the polydopamine-chitosan complex stabilizer.

[0079] A method for preparing a titanium-tungsten etching solution for integrated circuits includes the following steps: stirring and mixing nitric acid, 98% concentrated sulfuric acid, sodium dodecylbenzenesulfonate and water until homogeneous, adding polydopamine complexing stabilizer, stirring and mixing to obtain the titanium-tungsten etching solution for integrated circuits.

[0080] Test Example 1

[0081] The integrated circuits prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests using titanium-tungsten etching solution. The results are shown in Table 1.

[0082] Etching rate: The substrate forming the barrier layer is placed on an amorphous titanium-tungsten film with a film thickness of À, immersed in an etching solution at 40°C for 1 minute, then washed with water, dried and the barrier layer is peeled off. The etching amount is measured using a stylus-type film thickness gauge.

[0083] Etching residue: The substrate with the formed titanium-tungsten film was placed on a glass substrate and etched for 1.8 times the etching time calculated by the etching rate. The residue was then observed by an electron microscope and evaluated.

[0084] Table 1

[0085]

[0086] As can be seen from the table above, the titanium-tungsten etchant for integrated circuits prepared in Examples 1-3 of the present invention has a fast etching speed, leaves no residue after etching, has high uniformity of thickness after etching, and has a high utilization rate of etchant.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A titanium-tungsten etching solution for integrated circuits, characterized in that, The ingredients include: nitric acid, sulfuric acid, phosphoric acid, polydopamine-chitosan complex stabilizer, surfactant, and water; The polydopamine-chitosan complex stabilizer is prepared by dissolving chitosan in an acidic solution and then reacting it with dopamine hydrochloride under the action of a catalyst to form a polydopamine-chitosan copolymer, followed by the reaction with hydrochloric acid.

2. The titanium-tungsten etching solution for integrated circuits according to claim 1, characterized in that, It is prepared from the following raw materials in parts by weight: 5-10 parts nitric acid, 3-7 parts sulfuric acid, 15-20 parts phosphoric acid, 3-5 parts polydopamine-chitosan complex stabilizer, 1-2 parts surfactant, and 40-50 parts water.

3. The titanium-tungsten etching solution for integrated circuits according to claim 1, characterized in that, The sulfuric acid is concentrated sulfuric acid with a concentration greater than 98%.

4. The titanium-tungsten etching solution for integrated circuits according to claim 1, characterized in that, The surfactant is selected from at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfonate, sodium dodecyl sulfate, sodium tetradecyl sulfonate, sodium tetradecylbenzenesulfonate, sodium hexadecylbenzenesulfonate, sodium hexadecyl sulfonate, sodium hexadecyl sulfate, sodium octadecyl sulfonate, sodium octadecylbenzenesulfonate, and sodium octadecyl sulfate.

5. The titanium-tungsten etching solution for integrated circuits according to claim 1, characterized in that, The preparation method of the polydopamine-chitosan complex stabilizer is as follows: S1. Dissolve chitosan in acetic acid solution to obtain chitosan solution; S2. Add dopamine hydrochloride and catalyst to the chitosan solution obtained in step S1, heat and stir to react, and obtain polydopamine-chitosan copolymer; S3. Add the polydopamine-chitosan copolymer obtained in step S2 to hydrochloric acid, stir and react to obtain the polydopamine-chitosan complex stabilizer.

6. The titanium-tungsten etching solution for integrated circuits according to claim 5, characterized in that, The concentration of the acetic acid solution in step S1 is 3-5 wt%; the concentration of chitosan in the chitosan solution is 5-12 wt%.

7. The titanium-tungsten etching solution for integrated circuits according to claim 5, characterized in that, In step S2, the mass ratio of chitosan solution, dopamine hydrochloride, and catalyst is 100:15-20:2-3; the catalyst is a Tris-HCl solution with a pH of 5-6; the heating and stirring reaction is carried out at a temperature of 50-60℃ for 1-2 hours.

8. The titanium-tungsten etching solution for integrated circuits according to claim 5, characterized in that, The concentration of hydrochloric acid in step S3 is 2-4 mol / L; the stirring reaction time is 30-50 min.

9. The titanium-tungsten etching solution for integrated circuits according to claim 5, characterized in that, The specific preparation method of the polydopamine-chitosan complex stabilizer is as follows: S1. Dissolve chitosan in a 3-5 wt% acetic acid solution to obtain a 5-12 wt% chitosan solution; S2. Add 15-20 parts by weight of dopamine hydrochloride and 2-3 parts by weight of catalyst to 100 parts by weight of chitosan solution obtained in step S1, heat to 50-60℃, stir and react for 1-2 hours to obtain polydopamine-chitosan copolymer. The catalyst is a Tris-HCl solution with a pH of 5-6; S3. Add the polydopamine-chitosan copolymer obtained in step S2 to 2-4 mol / L hydrochloric acid and stir for 30-50 min to obtain the polydopamine-chitosan complex stabilizer.

10. A method for preparing a titanium-tungsten etchant for integrated circuits as described in any one of claims 1-9, characterized in that, The process includes the following steps: mixing nitric acid, sulfuric acid, phosphoric acid, surfactant and water until homogeneous, adding polydopamine complexing stabilizer, and mixing to obtain a titanium-tungsten etching solution for integrated circuits.

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