Titanium / tungsten nitride etching solution with long service life and high selection ratio

Abstract

The invention discloses a titanium nitride / tungsten etching solution with long service life and high selection ratio. The titanium nitride / tungsten etching solution comprises the following raw materials in percentage by mass: 30-70% of an acidic medium; 10-25% of a diffusant; 1-10% of a complexing agent; 0.1-1% of an accelerant; 0.01%-0.1% of a stabilizing agent; and the balance of deionized water. When the etching solution ensures that the etching rate of titanium nitride is 10-25 A / min, the selection ratio of titanium nitride / tungsten is increased to 500-1000, and the etching life reaches 24 hours.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic chemicals, and in particular relates to a titanium nitride / tungsten etching solution with a long service life and a high selectivity ratio. Background Art

[0002] Titanium nitride and tungsten are the inevitable material choices for advanced semiconductors. At the same time, as the process requirements continue to increase, the original low-selectivity etching solution can no longer meet the demand.

[0003] Tungsten and titanium nitride materials are widely used in integrated circuit manufacturing. Tungsten is widely used in metal conductive layers, gates, barrier layers or masks in integrated circuits due to its good semiconductor compatibility and adhesion. Similarly, titanium nitride (titanium-based metal) is often used as the bottom layer, barrier layer or adhesion layer material of other metal layers in integrated circuits due to its excellent conductivity and superconductivity. Especially in the manufacture of logic circuits, although ultra-large-scale integrated circuits are developing towards higher-end copper processes, the current MOCVD technology for depositing titanium nitride is often used as a tungsten-filled adhesion layer and barrier layer, which is an irreplaceable technology.

[0004] Existing titanium nitride and tungsten etching solutions are mostly used to etch titanium nitride and tungsten layers simultaneously, and cannot simultaneously meet the requirements of titanium nitride etching rate greater than 10A / min, selectivity greater than 500, and etching life greater than 24h.

[0005] Existing literature on titanium nitride and tungsten mainly deals with etching both of them simultaneously. The etching rate can be kept consistent through regulation. However, in the literature on selective etching of titanium nitride and tungsten, the selectivity and etching rate of titanium nitride are relatively low. It is necessary to develop an etching solution for titanium nitride and tungsten with high selectivity, high etching rate and long etching life. Summary of the invention

[0006] In view of the above technical problems, the present invention provides a titanium nitride / tungsten etching solution with a long life and high selectivity.

[0007] In order to achieve the above object, the present invention provides a titanium nitride / tungsten etching solution with a long life and high selectivity, characterized in that it comprises the following raw materials in mass percentage: 30~70% acidic medium; 10~25% diffusant; 1~10% complexing agent; 0.1~1% accelerator; 0.01~0.1% stabilizer; The balance was deionized water.

[0008] Preferably, the acidic medium is an aqueous solution with a mass fraction of 5 to 40%.

[0009] More preferably, the acidic medium is any one of an aqueous solution of sulfuric acid, perchloric acid, hydroiodic acid, hydrobromic acid, hydrochloric acid, phosphoric acid, boric acid, citric acid, oxalic acid, maleic acid, and p-toluenesulfonic acid.

[0010] The addition of the acidic medium in the present invention can provide an etching environment with a pH value less than 1, which is beneficial to the etching of titanium nitride and can also reduce the etching rate of tungsten to the maximum extent.

[0011] Preferably, the diffusant is an aqueous solution with a mass fraction of 10-30%.

[0012] More preferably, the diffusing agent is any one of acetic acid, isopropanol, hydrofluoric acid, methanol, formic acid, and ethanol.

[0013] The addition of the diffusing agent of the present invention can reduce the viscosity of the solution, facilitate the flow of the solution in the etching tank, and reduce the pump head pressure. On the other hand, it can increase the mass transfer rate of the etching solution in the high layer number and keep the etching rate of each position of the deep hole consistent.

[0014] Preferably, the complexing agent is a heterocyclic nitrogen-containing compound.

[0015] Further preferably, the complexing agent is any one of N,N,N',N'',N''-pentamethyldivinyltriamine, N,N,N',N'-tetramethyldecane-1,10-diamine, N,N,N'',N''-tetraisopropyldiethylenetriamine, N,N,N'',N''-tetrabutyldiethylenetriamine, N,N,5-trimethylfurfurylamine, N,N',N''-trimethyldiethylenetriamine, benzyl N,N,N',N'-tetraisopropylphosphorodiamidite, 2,4,7-triamino-6-phenylpteridine, and 1,3,5-triazine-2,4,6-triamine.

[0016] The addition of the complexing agent of the present invention can significantly reduce the etching rate of tungsten and increase the selectivity.

[0017] Preferably, the accelerator is any one of N-ethylpiperazine, 2-piperazineacetic acid, 2-piperazinone, imidazole, and pteridine.

[0018] The accelerator used in the present invention contains piperazine substances and symmetrical nitrogen-containing compounds which can increase the etching rate of titanium nitride.

[0019] Preferably, the stabilizer is any one of diammonium phosphate, ammonium sulfate, ammonium chloride, acetamide, and ammonium oxalate. The present invention adopts a stabilizer to maintain the low pH of the solution, continuously replenish the hydrogen ions in the solution, and increase the etching life of the solution.

[0020] The beneficial effects of the present invention are: 1. This experiment increases the etching selectivity of titanium nitride to tungsten to 500~1000, greatly improving the selectivity of these two materials for etching solution.

[0021] 2. When the etching selectivity ratio is reached, the titanium nitride etching rate is maintained at 10~25A / min. This rate improves the etching efficiency, reduces the time of the etching process, and maintains the consistency of the etching process at the upper and lower ends.

[0022] 3. The addition of stabilizer in the etching solution makes it have a longer life and increased stability. DETAILED DESCRIPTION

[0023] 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.

[0024] Example 1 A titanium nitride / tungsten etching solution with a long life and high selectivity ratio has a formula of: 30% phosphoric acid aqueous solution (mass fraction is 89%), 12% acetic acid solution (mass fraction is 20%), 6% N,N,N',N'',N''-pentamethyldiethylenetriamine solution, 0.5% N-ethylpiperazine, 0.2% ammonium chloride, and the remainder is deionized water.

[0025] Example 2 A titanium nitride / tungsten etching solution with a long life and high selectivity ratio has the following formula: 35% perchloric acid aqueous solution (mass fraction is 85%), 15% isopropanol aqueous solution (mass fraction is 10%), 1.2% N,N,N',N'-tetramethyldecane-1,10-diamine, 0.7% N-ethylpiperazine, 0.01% diammonium hydrogen phosphate, and the remainder is deionized water.

[0026] Example 3 A titanium nitride / tungsten etching solution with a long life and high selectivity ratio has the following formula: 45% hydroiodic acid aqueous solution (mass fraction is 78%), 20% hydrofluoric acid aqueous solution (mass fraction is 15%), 1.5% N,N,N'',N''-tetraisopropyldiethylenetriamine aqueous solution (mass fraction is 35%), 0.7% 2-piperazineacetic acid, 0.01% ammonium sulfate, and the remainder is deionized water.

[0027] Example 4 A titanium nitride / tungsten etching solution with a long life and high selectivity ratio has a formula of: 50% hydrobromic acid aqueous solution (mass fraction is 80%), 25% methanol solution (mass fraction is 12%), 2% N,N,N',N'',N''-pentamethyldiethylenetriamine solution, 0.8% 2-piperazinone, 0.01% ammonium oxalate, and the remainder is deionized water.

[0028] Example 5 A titanium nitride / tungsten etching solution with a long life and high selectivity ratio has a formula of: 30% hydrochloric acid solution (mass fraction is 18%), 25% formic acid aqueous solution (mass fraction is 14%), 3.5% N,N,N'',N''-tetrabutyldiethylenetriamine, 0.7% imidazole, 0.02% ammonium acetate, and the rest is deionized water.

[0029] Example 6 A titanium nitride / tungsten etching solution with a long life and high selectivity ratio has a formula of: 35% phosphoric acid aqueous solution (mass fraction is 19%), 10% ethanol aqueous solution (mass fraction is 12%), 1% N,N,5-trimethylfurfurylamine, 0.6% pteridine, 0.02% diammonium hydrogen phosphate, and the rest is deionized water.

[0030] Example 7 A titanium nitride / tungsten etching solution with a long service life and a high selectivity ratio has a formula of: 50% boric acid aqueous solution (mass fraction is 20%), 12% acetic acid aqueous solution (mass fraction is 20%), 1% N,N',N''-trimethyldiethylenetriamine, 1% 2-piperazineacetic acid, 0.02% ammonium sulfate, and the remainder is deionized water.

[0031] Example 8 A titanium nitride / tungsten etching solution with a long life and high selectivity ratio has a formula of: 60% citric acid aqueous solution (mass fraction is 20%), 25% acetic acid aqueous solution (mass fraction is 20%), 1% benzyl N,N,N',N'-tetraisopropylphosphorodiamidite, 1% 2-piperazineacetic acid, 0.02% ammonium chloride, and the remainder is deionized water.

[0032] Example 9 A titanium nitride / tungsten etching solution with a long service life and a high selectivity ratio has a formula of: 70% oxalic acid aqueous solution (mass fraction is 20%), 18% acetic acid aqueous solution (mass fraction is 20%), 1% 2,4,7-triamino-6-phenylpteridine, 1% N-ethylpiperazine, 0.02% ammonium acetate, and the remainder is deionized water.

[0033] Example 10 A titanium nitride / tungsten etching liquid with a long service life and a high selectivity ratio has a formula of: 70% maleic acid aqueous solution (mass fraction is 20%), 20% acetic acid aqueous solution (mass fraction is 20%), 1% 1,3,5-triazine-2,4,6-triamine, 1% N-ethylpiperazine, 0.02% ammonium oxalate, and the remainder is deionized water.

[0034] Embodiment 11 A titanium nitride / tungsten etching solution with a long service life and a high selectivity ratio has a formula of: 50% p-toluenesulfonic acid aqueous solution (mass fraction is 20%), 25% acetic acid aqueous solution (mass fraction is 20%), 1% 1,3,5-triazine-2,4,6-triamine, 1% pteridine, 0.02% ammonium oxalate, and the remainder is deionized water.

[0035] Comparative Example 1 A titanium nitride / tungsten etching solution with a long service life and a high selectivity ratio has a formula similar to that of Example 6 except that the phosphoric acid aqueous solution is not added.

[0036] Comparative Example 2 A titanium nitride / tungsten etching solution with a long service life and a high selectivity ratio has a formula similar to that of Example 6 except that no ethanol aqueous solution is added.

[0037] Comparative Example 3 A titanium nitride / tungsten etching solution with a long service life and a high selectivity ratio has a formula similar to that of Example 6 except that N,N,5-trimethylfurfurylamine is not added.

[0038] Comparative Example 4 A titanium nitride / tungsten etching solution with a long service life and a high selectivity ratio has a formula similar to that of Example 6 except that pteridine is not added.

[0039] Comparative Example 5 A titanium nitride / tungsten etching solution with a long service life and a high selectivity ratio has a formula similar to that of Example 6 except that diammonium hydrogen phosphate is not added.

[0040] Result detection: Take the titanium nitride and tungsten single pieces purchased from a certain company and cut them into small pieces of 10mm×10mm, and etch them as follows: Etching rate test: Place the monolith in isopropanol at 80°C and clean for 40 seconds to remove the attachments on the surface. Use a four-point test probe to measure the titanium nitride and tungsten monoliths. The initial thickness of the titanium nitride and tungsten monoliths is calculated by model fitting, and the average value is taken for the 4 points measured on the monolith. Then put the titanium nitride and tungsten monoliths into the etching solution for 5-10 minutes, clean them and blow them dry with nitrogen, use a four-point probe to test the resistance of the titanium nitride and tungsten etching monoliths after etching (keep the test points consistent before the moment), fit the calculation and take the average value to obtain the thickness of the titanium nitride and tungsten monoliths, and calculate the etching rate of the monoliths. The etching rates of titanium nitride and tungsten monoliths configured by the selective etching solutions of the above embodiments and comparative examples can be seen in Table 1.

[0041] Table 1 Effect of etching time on etching rate of uniform etching solution

[0042] Table 2 Effect of titanium nitride etching stability Time / h Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 0 17.65 25.25 13.31 21.67 10.89 12.51 17.22 19.11 6 17.63 25.32 13.33 21.69 10.88 12.55 17.21 19.32 12 17.68 25.31 13.34 21.64 10.85 12.53 17.56 19.14 18 17.65 25.23 13.32 21.63 10.88 12.51 17.12 19.21 24 17.68 25.25 13.34 21.64 10.83 12.54 17.24 19.16 Time / h Example 9 Example 10 Embodiment 11 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 0 14.26 15.42 16.22 2.33 5.27 12.49 3.49 12.53 6 14.25 15.44 16.25 2.21 5.49 12.43 3.44 11.25 12 14.32 15.49 16.24 2.43 5.44 12.13 3.45 10.36 18 14.31 15.44 16.24 2.12 5.40 12.14 3.54 8.12 24 14.18 15.43 16.22 2.03 5.37 12.33 3.49 4.25 As shown in Table 1, there is a significant difference in the etching rates of the etching solutions prepared in Examples 1-8 and Comparative Examples 1, 2, 3, and 4, indicating that the addition of an acid medium is the key to etching titanium nitride sheets, the addition of a promoter is more conducive to the etching of titanium nitride, the addition of a diffusing agent is more conducive to the etching of titanium nitride, and the addition of a complexing agent can significantly reduce the etching rate of tungsten. Comparative Example 5 verifies the long life related content of the present invention. When the etching time of Comparative Example 5 is extended to 24 hours, the etching rate is only 4.25A / min, which cannot meet the relevant requirements of the present invention.

Claims

1. A titanium nitride / tungsten etching solution with a long life and high selectivity, characterized in that: Including the following raw materials in mass percentage: 30~70% acidic medium; 10~25% diffusant; 1~10% complexing agent; 0.1~1% accelerator; 0.01~0.1% stabilizer; The balance was deionized water.

2. The titanium nitride / tungsten etching solution with a long life and high selectivity according to claim 1, characterized in that: The acidic medium is any one of aqueous solutions of sulfuric acid, perchloric acid, hydroiodic acid, hydrobromic acid, hydrochloric acid, phosphoric acid, boric acid, citric acid, oxalic acid, maleic acid and p-toluenesulfonic acid.

3. The titanium nitride / tungsten etching solution with a long life and high selectivity according to claim 2, characterized in that: The acidic medium is an aqueous solution with a mass fraction of 5-40%.

4. The titanium nitride / tungsten etching solution with a long life and high selectivity according to claim 1, characterized in that: The diffusing agent is any one of acetic acid, isopropanol, hydrofluoric acid, methanol, formic acid and ethanol.

5. The titanium nitride / tungsten etching solution with a long life and high selectivity according to claim 4, characterized in that: The diffusant is an aqueous solution with a mass fraction of 10-30%.

6. A titanium nitride / tungsten etching solution with a long life and high selectivity according to claim 1, characterized in that: The complexing agent is any one of N,N,N',N'',N''-pentamethyldivinyltriamine, N,N,N',N'-tetramethyldecane-1,10-diamine, N,N,N'',N''-tetraisopropyldiethylenetriamine, N,N,N'',N''-tetrabutyldiethylenetriamine, N,N,5-trimethylfurfurylamine, N,N',N''-trimethyldiethylenetriamine, benzyl N,N,N',N'-tetraisopropylphosphorodiamidite, 2,4,7-triamino-6-phenylpteridine, and 1,3,5-triazine-2,4,6-triamine.

7. The titanium nitride / tungsten etching solution with a long life and high selectivity according to claim 6, characterized in that: The complexing agent is an aqueous solution with a mass fraction of 15-35%.

8. A titanium nitride / tungsten etching solution with a long life and high selectivity according to claim 1, characterized in that: The accelerator is any one of N-ethylpiperazine, 2-piperazineacetic acid, 2-piperazinone, imidazole and pteridine.

9. The titanium nitride / tungsten etching solution with a long life and high selectivity according to claim 1, characterized in that: The stabilizer is any one of diammonium hydrogen phosphate, ammonium sulfate, ammonium chloride, ammonium acetate, and ammonium oxalate.

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