Cleaning solution for removing residues after polyimide etching

Abstract

The invention discloses a cleaning solution for removing residues after polyimide etching. The cleaning solution comprises the following main components: 0.1%-5% of ammonium bifluoride, 0.1%-2% of phosphoric acid, 0.01%-2% of a surfactant, 1%-10% of an inhibitor, 10%-65% of an organic solvent and the balance of water; reaction active substances are ammonium bifluoride and phosphoric acid, and residues after etching are converted into soluble substances under the synergistic effect of the ammonium bifluoride and the phosphoric acid; the use of the surfactant can effectively reduce the interfacial tension between the cleaning solution and the two phases of the wafer and improve the interfacial reaction activity; the inhibitor controls the corrosion rate of the metal and the dielectric layer; the organic solvent and the water are used as main solvents, so that the capability of cleaning residues after etching is enhanced. The cleaning solution provided by the invention has the advantages of no permeation to polyimide, low etching rate to a dielectric layer, good cleaning performance to photoresist and residues after etching, long service life and no chemical damage risk.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic manufacturing cleaning agents, and in particular relates to a cleaning liquid for removing residues after polyimide etching. Background Art

[0002] Polyimide is a polymer material with excellent thermal stability. It can work for a long time in high temperature air at 200℃. Its physical and mechanical properties and chemical stability can be made into film materials with corrosion resistance and high temperature resistance. Polyimide is easy to flatten and has excellent adhesion properties. It can be used as a material for surface sacrificial layer technology. The resistivity is 10 15 ~10 16 Ωcm, good electrical insulation and processability, it is widely used as a dielectric insulating layer in electronic manufacturing. However, polyimide has a strong polar structure and is hygroscopic. Chemical solutions can easily penetrate into the interior of polyimide, resulting in an increase in the dielectric constant of the material itself. In addition, during the dry etching of photoresist, the residues formed after polyimide is etched are not easy to remove and adhere to the inner wall of the wafer. Failure to clean it in time is not conducive to the subsequent coating process and will lead to product defects and reduced yield.

[0003] Ammonium fluoride-containing cleaning agents have the advantage of strong residue removal ability, but ammonium fluoride has a faster etching rate on the dielectric layer material and destroys the wafer structure. Ammonium fluoride is highly irritating and long-term contact can cause dental fluorosis and skeletal fluorosis. There are specific requirements for equipment materials, resulting in higher equipment production costs. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a cleaning solution for removing residues after polyimide etching, which does not damage the metal interconnect layer, has a low etching rate for the dielectric layer material, can effectively remove the residues after polyimide etching without solution penetration, can be directly used for cleaning wafer structures involving polyimide film layers, has a safer and simpler use process, and reduces costs.

[0005] The present invention provides a cleaning solution for removing residues after polyimide etching, comprising the following components by mass fraction: 0.1%-5% ammonium bifluoride, 0.1%-2% phosphoric acid, 0.01%-2% surfactant, 1%-10% inhibitor, 10%-65% organic solvent and the balance water;

[0006] Preferably, the mass fraction of ammonium bifluoride in the cleaning solution is 0.1%-1.5%.

[0007] Preferably, the mass fraction of phosphoric acid in the cleaning solution is 0.1-0.5%.

[0008] Preferably, the mass fraction of the surfactant in the cleaning solution is 0.01-0.1%.

[0009] Preferably, the mass fraction of the inhibitor in the cleaning solution is 5-8%.

[0010] Preferably, the mass fraction of the organic solvent in the cleaning solution is 30-65%.

[0011] Preferably, the surfactant is one or more of cetearyl alcohol polyether-10, nonylphenol polyether-10, lauryl sulfonated succinic acid diammonium ester, coconut fatty acid diethylamide, monolauryl phosphate, glyceryl stearate, sorbitan laurate, dodecyl dimethyl amine oxide, N-lauryl pyrrolidone, acetone oxime, dodecylbenzene sulfonic acid, Tween, chitin, and D-isoascorbic acid, and more preferably one or more of lauryl sulfonated succinic acid diammonium ester, nonylphenol polyether-10, N-lauryl pyrrolidone, acetone oxime, Tween, and chitin.

[0012] Preferably, the inhibitor is benzotriazole, 2-mercaptobenzothiazole, 2-methylimidazole, 3-amino-1,2,4-triazole, 5-methyl-benzotriazole, 5-butyl-benzotriazole, 5-hexyl-benzotriazole, 5-octyl-benzotriazole, 5-dodecyl-benzotriazole, 3-amino-1,2,4-triazole, 1H-naphthotriazole, 5-chloro-benzotriazole, 5-nitrogen dioxide-benzotriazole, 1-hydroxybenzotriazole, hydroxyethylethylenediaminetriacetic acid, valeric acid, tiglic acid, 10-undecenoic acid, arachidonic acid, 2-furan acrylic acid, 2-phenyl acrylic acid, (E)-9-tetradecenoic acid, methyltrifluoroacrylic acid, erucic acid, 3,3-dimethylacrylic acid, 3-(pyridine-4-)acrylic acid, 3-indoleacrylic acid, 2-acetamidoacrylic acid, 3-(2-thiophene)acrylic acid, The invention further comprises one or more of benzotriazole, 2-mercaptobenzothiazole, 2-methylimidazole, 3-amino-1,2,4-triazole, 5-methyl-benzotriazole, 5-butyl-benzotriazole, 5-hexyl-benzotriazole, 5-octyl-benzotriazole, 5-dodecyl-benzotriazole, 3-amino-1,2,4-triazole, 1H-naphthotriazole, 5-chloro-benzotriazole, 5-nitrogen dioxide-benzotriazole, 1-hydroxybenzotriazole, hydroxyethylethylenediaminetriacetic acid, 2-furanacrylic acid, 2-phenylacrylic acid, 3,3-dimethylacrylic acid, 3-(pyridine-4-)acrylic acid, 3-indoleacrylic acid, 2-acetamidoacrylic acid, 3-(2-thienyl)acrylic acid, and 2-(trifluoromethyl)acrylic acid.

[0013] Preferably, the organic solvent is one or more of dimethyl sulfone, diethyl sulfone, cyclopentane, dimethyl sulfoxide, diethyl sulfoxide, benzyl sulfoxide, 1-hydroxypyrrolidine, N-hydroxysuccinimide, N-hydroxypiperidine, 1-hydroxy-2-methyl-pyrrolidine, 1-hydroxy-3-methyl-pyrrolidine, 1-hydroxy-2-piperidone, 1-hydroxy-4-methylpiperidine, N-hydroxy-2-pyrrolidone, N-methoxy-2-pyrrolidone, N-hydroxysuccinimide, N-hydroxymaleimide, N-vinylpyrrolidone, N-methylmorpholine nitrogen oxide, and oxidized-4-methylmorpholine monohydrate, and more preferably cyclopentane, dimethyl sulfoxide, benzyl sulfoxide, N-methylmorpholine nitrogen oxide, and oxidized-4-methylmorpholine monohydrate.

[0014] The beneficial effects of the present invention are:

[0015] The etching rate of metal and dielectric materials is controlled by adjusting the pH value through the ammonium ions and phosphate, hydrogen phosphate, and dihydrogen phosphate ions generated by the hydrolysis of ammonium bifluoride and phosphoric acid under different water content conditions. At the same time, the phosphates of different valence states after hydrolysis have water retention properties, which reduce the volatilization of water content in the cleaning liquid system and increase the solubility of etching residues. Phosphates undergo double decomposition reactions with metal salts on the surface of the wafer, further reducing the adsorption concentration of metal ions on the surface of the wafer and improving the cleanliness of the wafer. DETAILED DESCRIPTION

[0016] 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.

[0017] The reagents used in the following examples are all commercially available and are added into a beaker one by one according to the proportions and mixed evenly.

[0018] Examples 1-10

[0019] Prepare the cleaning solution according to the various raw materials and proportions in Table 1:

[0020] Table 1 Cleaning solution formula

[0021]

[0022]

[0023] Comparative Example 1

[0024] A cleaning solution containing only 0.5% ammonium bifluoride solution.

[0025] Comparative Example 2

[0026] A cleaning solution containing only 0.5% ammonium fluoride solution.

[0027] Comparative Example 3

[0028] A cleaning solution, having the same formula as that of Example 1, except that the ammonium bifluoride is replaced by an equal amount of ammonium fluoride.

[0029] Comparative Example 4

[0030] A cleaning solution, having the same formula as that of Example 1, except that phosphoric acid is not added.

[0031] Comparative Example 5

[0032] A cleaning solution, having the same formula as that of Example 1, except that no surfactant is added.

[0033] Comparative Example 6

[0034] A cleaning solution, having the same formula as that of Example 1, except that no organic solvent is added.

[0035] Comparative Example 7

[0036] A cleaning solution, having the same formulation as that of Example 11, except that the inhibitor is replaced by an equal amount of 2-propenyl acrylic acid.

[0037] Comparative Example 8

[0038] A cleaning solution, having the same formulation as that of Example 11, except that the inhibitor is replaced by an equal amount of 4-chlorocinnamic acid.

[0039] Comparative Example 9

[0040] A cleaning solution, having the same formulation as that of Example 11, except that the inhibitor is replaced by an equal amount of ferulic acid.

[0041] Comparative Example 10

[0042] A cleaning solution, having the same formulation as in Example 11, except that the inhibitor is replaced by an equal amount of thiourea.

[0043] The cleaning of the wafer structure after etching the polyimide film layer was performed by spraying the cleaning solution prepared in the above embodiment and comparative example at 30-50° C. for 3-10 min. After the cleaning, the wafer was rinsed with deionized water at room temperature and then dried with high-purity nitrogen. The etching rate of the film layer and the cleaning effect on the wafer were evaluated using the standards in Table 2. The evaluation results are shown in Table 3:

[0044] Table 2 Evaluation criteria for corrosion conditions and cleaning effects

[0045]

[0046] Table 3 Cleaning effect of different cleaning solutions on wafers

[0047]

[0048]

[0049] It can be seen from Table 3 that the cleaning solution combinations prepared in Examples 1, 4, 8, 11, and 13 all have excellent removal capabilities for the etching residues on the wafer, and the etching rates for the non-metallic film material SiO2 and the metal film material Cu are between 0.04 and 0.13. Within, the protection effect is good.

[0050] It can be seen from Comparative Examples 1 to 4 that the use of ammonium bifluoride or ammonium fluoride alone will increase the etching rate of non-metallic film material SiO2; it can be seen from Comparative Examples 5 to 6 that the surfactant and organic solvent selected in the present invention have a positive effect on the cleaning performance of the product, and reducing their dosage cannot achieve the best cleaning effect. It can be seen from Comparative Examples 7 to 10 that the inhibitor selected in the present invention, after being compounded in a specific ratio with ammonium bifluoride, phosphoric acid, surfactant, and organic solvent in the formula system, has excellent cleaning performance on the residue after polyimide etching.

Claims

1. A cleaning solution for removing residues after polyimide etching, characterized in that: The invention comprises the following components: 0.1%-5% ammonium bifluoride, 0.1%-2% phosphoric acid, 0.01%-2% surfactant, 1%-10% inhibitor, 10%-65% organic solvent, and the balance is water.

2. A cleaning solution for removing polyimide etching residues according to claim 1, characterized in that: The surfactant is one or more of cetearyl alcohol polyether-10, nonylphenol polyether-10, polysorbate-20, coconut fatty acid diethylamide, glyceryl stearate, sorbitan laurate, dodecyl dimethyl amine oxide, N-lauryl pyrrolidone, acetone oxime, dodecylbenzene sulfonic acid, Tween, chitin, and D-isoascorbic acid.

3. The cleaning solution for removing polyimide etching residues according to claim 1, characterized in that: The inhibitor is one or more of benzotriazole, 2-mercaptobenzothiazole, 2-methylimidazole, 3-amino-1,2,4-triazole, 5-methyl-benzotriazole, 5-butyl-benzotriazole, 5-hexyl-benzotriazole, 5-octyl-benzotriazole, 5-dodecyl-benzotriazole, 3-amino-1,2,4-triazole, 1H-naphthotriazole, 5-chloro-benzotriazole, 5-nitrogen dioxide-benzotriazole, 1-hydroxybenzotriazole, and unsaturated carboxylic acid.

4. A cleaning solution for removing polyimide etching residues according to claim 3, characterized in that: The inhibitor unsaturated carboxylic acid is any one of hydroxyethylethylenediaminetriacetic acid, valeric acid, tiglic acid, 10-undecenoic acid, arachidonic acid, cycloalkanoic acid, 2-furanacrylic acid, 2-phenylacrylic acid, (E)-9-tetradecenoic acid, methyltrifluoroacrylic acid, erucic acid, 3,3-dimethylacrylic acid, 3-(pyridine-4-)acrylic acid, 3-indoleacrylic acid, 2-acetamidoacrylic acid, 3-(2-thienyl)acrylic acid, and 2-(trifluoromethyl)acrylic acid.

5. The cleaning solution for removing polyimide etching residues according to claim 1, characterized in that: The water is ultrapure water with a resistivity of 18 MΩ*cm at 25°C.

6. The cleaning solution for removing polyimide etching residues according to claim 1, characterized in that: The organic solvent is one or more of dimethyl sulfone, diethyl sulfone, sulfolane, dimethyl sulfoxide, diethyl sulfoxide, benzyl sulfoxide, 1-hydroxypyrrolidine and derivatives thereof.

7. The cleaning solution for removing polyimide etching residues according to claim 6, characterized in that: The 1-hydroxypyrrolidine and its derivatives have the following general structural formula: The substituents R1 and R2 are independently selected from one or more of hydrogen atom, methyl, ethyl, methoxy, ethoxy, hydroxyl, carboxyl, and vinyl; X is independently selected from one of carbon atom and oxygen atom; and the value of n is 1 or 2.

8. The cleaning solution for removing polyimide etching residues according to claim 7, characterized in that: The substituent R1 is located at one of the 2nd, 3rd and 4th substitution positions in the heterocycle.

9. The cleaning solution for removing polyimide etching residues according to claim 7, characterized in that: In the general structural formula, the substituents R1 and R2 have two or more substituents.

10. A cleaning solution for removing polyimide etching residues according to any one of claims 1 to 9, characterized in that: The cleaning fluid is used in the field of electronic manufacturing, including the field of cleaning agent technology for semiconductor integrated circuit manufacturing.

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