Cleaning solution used after chemical mechanical polishing of metal grid electrode, and preparation method and application thereof

Abstract

The invention provides a cleaning solution for a metal gate after chemical mechanical polishing as well as a preparation method and application of the cleaning solution. The cleaning solution for the metal gate after chemical mechanical polishing comprises the following components in parts by weight: 1-10 parts of a biotin polyethylene glycol derivative; 0.1-1 part of a corrosion inhibitor; 10-25 parts of a complexing agent; 10-20 parts of an organic solvent; 50 to 70 parts of ultrapure water; the biotin polyethylene glycol derivative is selected from one or more of biotin polyethylene glycol folic acid, biotin polyethylene glycol dimercaptopyridine and biotin polyethylene glycol rhodamine. The invention also discloses a preparation method and application of the cleaning solution after chemical mechanical polishing of the metal gate. The cleaning fluid after chemical mechanical polishing of the metal gate is high in cleaning capacity, the surface roughness of a cleaned chip is low, and the cleaning fluid has good application prospects and industrial popularization potential in the field of cleaning of semiconductor chips after chemical mechanical polishing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor material cleaning, in particular to a post-chemical mechanical polishing (CMP) cleaning solution for metal gate, and a preparation method and application thereof. BACKGROUND

[0002] With the continuous reduction of device size, the material surface after chemical mechanical polishing (CMP) will have problems such as large roughness, polishing liquid residue, impurities, etc., which are easy to cause electronic device noise and make the electronic characteristics inconsistent, thereby seriously affecting the device performance. Therefore, the cleaning effect after CMP is directly related to the yield of the device.

[0003] During chemical mechanical polishing, a polishing liquid containing silica sol is usually used. The main component SiO2 of silica sol is easy to form a new Si-O-M covalent bond with the broken chemical bond on the surface of the metal gate, so that the silica sol is adsorbed on the surface of the metal gate and becomes one of the main objects of post-CMP cleaning.

[0004] In the prior art, a strong alkaline cleaning solution is generally used to clean the silica sol film at a temperature greater than 90℃. However, with the line width of integrated circuits entering the technology node below 45nm, the disadvantages of the strong alkaline cleaning solution are gradually exposed, such as the problem of the increase of the chip surface roughness caused by the non-uniform corrosion of the fine lines. SUMMARY

[0005] The purpose of the present application is to solve the problems in the prior art that the post-CMP cleaning solution is difficult to remove the residual silica sol film on the surface of the metal gate and the chip surface roughness increases after cleaning. A post-CMP cleaning solution for metal gate is proposed, which has strong cleaning ability, low chip surface roughness after cleaning, and good application prospect and industrialization potential in the field of post-CMP cleaning of semiconductor chips.

[0006] It should be noted that in the present application, unless otherwise specified, the specific meaning of "including" involved in the composition limitation and description includes both the open "including", "containing" and the like, and the closed "consisting of", "consisting of" and the like.

[0007] To achieve the above purpose, the technical solution adopted by the present application is: a post-CMP cleaning solution for metal gate, comprising the following components in a weight ratio:

[0008]

[0009] Further, the biotin polyethylene glycol derivative is one or more of biotin polyethylene glycol folic acid, biotin polyethylene glycol dimercapto pyridine and biotin polyethylene glycol rhodamine.

[0010] Further, the biotin polyethylene glycol derivative is preferably biotin polyethylene glycol rhodamine.

[0011] Further, the biotin polyethylene glycol derivative compound is 5-8 parts.

[0012] The biotin polyethylene glycol derivative is creatively introduced in the present application, which can be adsorbed on the surface of the metal gate, at the same time, can penetrate into the gap between the silica sol and the surface of the metal gate, and extend to the deep, and wrap the remaining impurities such as silica sol; at the same time, the biotin part of the biotin polyethylene glycol derivative can chelate the metal ions remaining on the surface of the metal gate to form a complex, and the biotin polyethylene glycol derivative contains a hydrophilic polyethylene glycol group, which can greatly improve the solubility of the complex, and is beneficial to its uniform dispersion in the cleaning liquid system, and effectively removes the impurity particles on the metal surface by physical adsorption. The biotin polyethylene glycol derivative of the present application can be adsorbed on the surface of the aluminum gate, effectively inhibiting the non-uniform corrosion of the metal surface, and avoiding the problem of increased roughness caused by the non-uniform corrosion.

[0013] Further, the corrosion inhibitor is a sulfonamide compound.

[0014] Further, the corrosion inhibitor is one or more of sulfonamide isoxazole, sulfanilamide, sulfadimethoxine, sulfonamide quinolone and sulfonamide-5-methoxy pyrimidine.

[0015] Further, the corrosion inhibitor is preferably sulfadimethoxine.

[0016] Further, the corrosion inhibitor is 0.3-0.7 parts.

[0017] Further, the mass ratio of the biotin polyethylene glycol derivative and the corrosion inhibitor is 10-16:1.

[0018] The present application uses N-heterocyclic substituted sulfonamide compounds as corrosion inhibitors, which contain N-heterocyclic, amino and sulfonamide groups, can form coordination bonds by combining the lone pair of electrons with the empty orbit of Al, and these atoms will become the adsorption center of the corrosion inhibitor molecules, which can inhibit corrosion by isolating the solution. The corrosion inhibitor of the present application can synergistically act with the biotin polyethylene glycol derivative, which contains a large number of ethoxyl groups, can combine with the N-heterocyclic substituted sulfonamide compounds to form hydrogen bonds, and further form a large hydrogen bond network, which can quickly assist the corrosion inhibitor molecules to migrate to the surface of the Al gate, and adsorb on the metal surface to form a film, further inhibit the corrosion of the metal, avoid the redeposition of metal ions, and improve the cleaning efficiency; thereby effectively avoiding the problem of non-uniform corrosion in the cleaning process, and reducing the roughness of the surface of the Al gate.

[0019] Further, the complexing agent is selected from organic phosphonic acid derivatives.

[0020] Further, the complexing agent is one or more of hydroxyethylidene diphosphonic acid, aminotri(methylene) phosphonic acid, ethylenediamine tetra(methylene) phosphonic acid, 1,3-propylene diphosphonic acid and 4-aminobutyl phosphonic acid.

[0021] Further, the complexing agent is preferably hydroxyethylidene diphosphonic acid and / or 4-aminobutyl phosphonic acid.

[0022] Further, the complexing agent is most preferably hydroxyethylidene diphosphonic acid.

[0023] Further, the complexing agent is 15-20 parts.

[0024] Further, the mass ratio of the complexing agent to the biotin polyethylene glycol derivative is 1.5-4:1.

[0025] The present application uses an organic phosphonic acid derivative as a complexing agent. The organic phosphonic acid derivative contains a highly active phosphonic group, which can accelerate the dissolution of the Al surface oxide layer, complex with more Al ions to form a large number of metal ion complexes. Under the synergistic action of the biotin polyethylene glycol derivative, a large number of metal ion complexes are uniformly dispersed in the cleaning liquid system, improving the cleaning effect of the entire system. At the same time, the p heteroatom with strong adsorption capacity in the molecular structure of the complexing agent can quickly migrate to the Al gate metal surface, form physical adsorption, prevent further oxidation of the Al metal, and have better corrosion inhibition effect on the Al gate metal. At the same time, it can be well removed in the subsequent water washing process.

[0026] Further, the pH of the metal gate chemical mechanical polishing after cleaning solution is 1-6.

[0027] Further, the pH of the metal gate chemical mechanical polishing after cleaning solution is preferably 2-4.

[0028] Further, the organic solvent is one or more of dimethyl sulfoxide, N,N-dimethylformamide, ethanol, methanol and acetone.

[0029] Further, the organic solvent is preferably dimethyl sulfoxide.

[0030] Further, the organic solvent is 13-18 parts.

[0031] Further, the ultrapure water is deionized water with a resistance of ≥18MΩ.

[0032] Further, the ultrapure water is 55-65 parts.

[0033] Another object of the present application also discloses a preparation method of a metal gate chemical mechanical polishing after cleaning solution, comprising the following steps:

[0034] S1: respectively take the respective amount of each component;

[0035] S2: the corrosion inhibitor, biotin polyethylene glycol derivative and organic solvent are added into a container, after stirring uniformly, the complexing agent and ultrapure water are added, and mixing is carried out until all materials are completely dissolved, so that the metal gate chemical mechanical polishing after cleaning solution is prepared.

[0036] Another object of the present application also discloses the application of the metal gate chemical mechanical polishing after cleaning solution in the field of semiconductor chip chemical mechanical polishing after cleaning.

[0037] Further, the metal gate chemical mechanical polishing after cleaning solution is especially suitable for cleaning after Al gate CMP polishing.

[0038] The metal gate chemical mechanical polishing after cleaning solution, the preparation method and the application of the present application have the following advantages compared with the prior art:

[0039] 1) The biotin polyethylene glycol derivative is creatively introduced in the present application, which can be adsorbed on the metal gate surface, penetrate into the gap between the silica sol and the metal gate surface, and extend to the deep place, like a "wedge" into the interface, play the role of splitting, and wrap the residual impurities such as silica sol; at the same time, the biotin part in the biotin polyethylene glycol derivative can chelate the residual metal ions on the metal gate surface to form a complex product, and the hydrophilic polyethylene glycol group contained in the biotin polyethylene glycol derivative can greatly improve the solubility of the complex product, and is beneficial to its uniform dispersion in the cleaning solution system, effectively removing the impurity particles on the metal surface relying on physical adsorption. In addition, the biotin polyethylene glycol derivative in the present application can be adsorbed on the aluminum gate surface, effectively inhibiting the non-uniform corrosion of the metal surface, and avoiding the problem of increased roughness.

[0040] 2) The N-heterocyclic substituted sulfanilamide compound is used as the corrosion inhibitor in the present application, which contains N-heterocyclic, amino and sulfonamide groups, can form a coordination bond with the empty orbital of Al through its lone pair of electrons, and these atoms become the adsorption center of the corrosion inhibitor molecule, which can inhibit corrosion by isolating the solution. The corrosion inhibitor can synergistically act with the biotin polyethylene glycol derivative, the biotin polyethylene glycol derivative contains a large number of ethoxy groups, which can form hydrogen bonds with the N-heterocyclic substituted sulfanilamide compound, and then form a large hydrogen bond network, which can quickly assist the corrosion inhibitor molecules to migrate to the Al gate surface, and adsorb on the metal surface to form a film, further inhibit the corrosion of the metal, avoid the redeposition of metal ions, and improve the cleaning efficiency; thereby effectively avoiding the problem of uneven corrosion in the cleaning process, and reducing the roughness of the Al gate surface.

[0041] 3) The application uses organic phosphonic acid derivatives as complexing agents, which contain active phosphonic groups that can accelerate the dissolution of the Al surface oxide layer and complex with more Al ions to form a large number of metal ion complexes. In the synergistic effect of biotin polyethylene glycol derivatives, a large number of metal ion complexes are uniformly dispersed in the cleaning liquid system, improving the cleaning effect of the entire system. At the same time, the p heteroatom in the molecular structure of the complexing agent has strong adsorption capacity, which helps the corrosion inhibitor molecules to quickly migrate to the Al gate metal surface, form physical adsorption, prevent further oxidation of Al metal, and has better corrosion inhibition effect on Al gate metal. At the same time, it can be well removed in the subsequent water washing process.

[0042] 4) The corrosion inhibitor can synergistically inhibit corrosion with biotin polyethylene glycol derivatives. The N heterocycle, amino and sulfonamide groups contained in the corrosion inhibitor form hydrogen bonds with the ethoxy groups in the biotin-polyethylene glycol derivative, and then form a large hydrogen bond network. At the same time, the amino group in the corrosion inhibitor and the ethoxy group in the biotin-polyethylene glycol derivative can also coordinate with metal ions. The large hydrogen bond network and coordination effect promote each other, adsorb on the metal surface to form a film, inhibit metal corrosion, and avoid the redeposition of metal ions, thereby improving the cleaning efficiency. At the same time, the biotin-polyethylene glycol derivative can make the corrosion inhibitor molecules uniformly adsorbed on the Al gate surface under the synergistic effect of the organic phosphonic acid compound, thereby effectively avoiding the increase in surface flatness caused by uneven corrosion during cleaning, and greatly reducing the roughness of the Al gate surface.

[0043] 5) The complexing agent and biotin polyethylene glycol derivative have a synergistic cleaning effect. The organic phosphonic acid derivative contains active phosphonic groups that can accelerate the dissolution of the Al surface oxide layer and complex with more Al ions to form a large number of metal ion complexes. In the synergistic effect of biotin polyethylene glycol derivatives, a large number of metal ion complexes are uniformly dispersed in the cleaning liquid system, improving the cleaning effect of the entire system. At the same time, the p heteroatom and the multiple hydroxyl hydrophilic groups in the molecular structure of the complexing agent have strong adsorption capacity, which makes the corrosion inhibitor molecules quickly adsorb on the Al gate metal surface under the synergistic effect of biotin-polyethylene glycol derivatives, further enhances the adsorption force, prevents further oxidation of Al metal, and has better corrosion inhibition effect on Al gate metal.

[0044] 6) The metal gate chemical mechanical polishing cleaning liquid of the application can effectively chelate metal ions, remove organic residues and particles, and greatly avoid the problem of uneven Al gate surface after cleaning through the synergistic effect of biotin polyethylene glycol derivatives, corrosion inhibitors and complexing agents.

[0045] Therefore, the metal gate chemical mechanical polishing post-cleaning solution has a very good application prospect and large-scale industrialization popularization potential in the field of semiconductor chip chemical mechanical polishing post-cleaning. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 The SEM image of the wafer before cleaning is shown in Figure 1, with a magnification of 5000 times.

[0047] Figure 2 The SEM image of the wafer after cleaning with the cleaning solution of Example 1 is shown in Figure 2, with a magnification of 5000 times. DETAILED DESCRIPTION

[0048] Hereinafter, the present application will be further described in conjunction with examples. The description of the technical features described below is based on representative embodiments, specific examples of the present application, but the present application is not limited to these embodiments, specific examples. It should be noted that:

[0049] Unless otherwise specified, the units used in the specification are international standard units, and the numerical values and numerical ranges appearing in the present application should be understood to include the inevitable systematic errors in industrial production.

[0050] In the specification, the numerical range represented by "numerical value A ~ numerical value B" means a range including the end point values A and B.

[0051] In the specification, the numerical range represented by "above" or "below" means a numerical range including the number.

[0052] In the specification, the meaning represented by "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0053] In the specification, "optional" or "optionally" means that some substances, components, steps, conditions, etc. are used or not used.

[0054] In the specification, when "room temperature" or "room temperature" is used, the temperature can be 15-25℃.

[0055] In the specification, the reagents or instruments not marked with the manufacturer are all conventional products that can be obtained by market purchase.

[0056] Examples 1-9

[0057] Examples 1-9 disclose a variety of metal gate chemical mechanical polishing post-cleaning solutions, which contain the components and weight ratio as shown in Table 1, and the preparation method is as follows:

[0058] S1: weigh each component according to its respective amount;

[0059] S2: The corrosion inhibitor, biotin polyethylene glycol derivative, and organic solvent are added to a container, stirred until the solids are completely dissolved, then the complexing agent and ultrapure water are added, mixed until all materials are completely dissolved, to prepare the post-chemical mechanical polishing cleaning solution for metal gate.

[0060] Table 1 Composition and ratio of post-chemical mechanical polishing cleaning solution for metal gate of Examples 1-9

[0061]

[0062]

[0063] Comparative Examples 1-4

[0064] Comparative Examples 1-4 disclose various post-chemical mechanical polishing cleaning solutions, which contain the components and weight ratios as shown in Table 2, and the preparation method is the same as Example 1.

[0065] Table 2 Composition and ratio of post-chemical mechanical polishing cleaning solution for metal gate of Comparative Examples 1-4

[0066]

[0067]

[0068] The post-chemical mechanical polishing cleaning solution for metal gate of Examples 1-9 and the post-chemical mechanical polishing cleaning solution of Comparative Examples 1-4 were tested respectively, and the test method and test results are as follows:

[0069] The test method for performance 1, the corrosion rate of metal, is as follows:

[0070] The Al wafer was cut into 2cm*2cm squares, treated with isopropyl alcohol at room temperature for 5min, washed with pure water, dried with nitrogen, and then the front film thickness was measured with a four-point probe instrument. The post-chemical mechanical polishing cleaning solution was diluted with ultrapure water to 50 times to obtain a diluted cleaning solution, and the Al wafer was immersed in 50ml of the diluted cleaning solution for corrosion. After 2h, the Al wafer was taken out, washed with pure water, dried with nitrogen, and then the back film thickness was measured with a four-point probe instrument, and a microscope picture was taken for comparison. The corrosion rate calculation formula is as follows:

[0071] The test method for performance 2, the cleaning effect, is as follows:

[0072] To characterize the hydrophilicity of the Al wafer surface in the post-chemical mechanical polishing cleaning of Al, a contact angle measuring instrument was used for testing. Deionized water was dropped on the surface of the Al wafer, and the contact angle tester was used to analyze the angle size to determine the hydrophilicity and hydrophobicity of the Al wafer surface. According to the hydrophilicity and hydrophobicity of the Al wafer surface, the removal of residues was determined.

[0073] The fresh Al wafer surface is hydrophilic (the contact angle of fresh Al wafer surface with deionized water is 32°, lower than which indicates that there is no residue on the Al surface, and higher than which indicates that there is residue on the Al surface), the contact angle of deionized water on the Al wafer surface is small, and the Al wafer surface is hydrophobic when there is organic residue on the Al wafer surface, and the contact angle of deionized water on the Al wafer surface is large.

[0074] The test method of performance 3 roughness is as follows:

[0075] Each chemical mechanical polishing after cleaning solution is diluted 50 times with ultrapure water to prepare a diluted cleaning solution, and then the Al wafer is placed in the diluted cleaning solution for immersion for 2 h, washed with deionized water and dried with nitrogen, and the AFM measurement value is measured.

[0076] Table 3 test data

[0077]

[0078] Based on Table 3, it can be seen that the Al corrosion after cleaning with the metal gate chemical mechanical polishing after cleaning solution of the present application examples 1-8 is in the range of 0.0001-0.0003 μm / min, the corrosion rate is small, the surface roughness is low, the roughness is 2.06-4.19 nm, the contact angle is less than 32°, and there is no residue on the Al surface. The Al corrosion after cleaning with the chemical mechanical polishing after cleaning solution of comparative examples 1-4 is in the range of 0.0004-0.0006 μm / min; the surface roughness is 4.82-6.53 nm.

[0079] The chemical mechanical polishing after cleaning solution of comparative example 1 uses biotin instead of biotin polyethylene glycol rhodamine, because it does not contain polyethylene glycol, the dispersibility and permeability decrease, leading to uneven corrosion of the metal surface and incomplete removal of the silica sol, the surface roughness and contact angle increase, and because biotin does not contain ethoxy, it cannot form a hydrogen bond network with the corrosion inhibitor, so the corrosion rate increases;

[0080] The chemical mechanical polishing after cleaning solution of comparative example 2 uses polyethylene glycol instead of biotin polyethylene glycol rhodamine, because it does not contain biotin, the complexation of metal ions decreases, and the adsorption sites decrease, leading to an increase in the corrosion rate of the metal;

[0081] The chemical mechanical polishing after cleaning solution of comparative example 3 uses amino polyethylene glycol thiol instead of biotin polyethylene glycol rhodamine, leading to an increase in the corrosion rate of the metal;

[0082] The chemical mechanical polishing after cleaning solution of comparative example 4 uses 2-aminopyrimidine as a corrosion inhibitor, because 2-aminopyrimidine does not contain a sulfonamide group, the adsorption of Al metal is weak, leading to an increase in the corrosion rate.

[0083] Regarding the drawings, from Figure 1 ​​It can be seen that there are some residues on the wafer surface before cleaning, and Figure 2 It can be seen that the residues on the wafer surface after cleaning by the cleaning solution of Example 1 are removed, and the wafer surface is relatively clean. Through Figure 1 and Figure 2 By comparison, it is proved that the cleaning solution of the present application has a good cleaning effect on residues.

[0084] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A cleaning solution for metal gates after chemical mechanical polishing, characterized in that, The components include the following weight proportions:

2. The cleaning solution after chemical mechanical polishing of metal gates according to claim 1, characterized in that, The biotin-polyethylene glycol derivative is one or more of biotin-polyethylene glycol folic acid, biotin-polyethylene glycol dimercaptopyridine, and biotin-polyethylene glycol rhodamine.

3. The cleaning solution after chemical mechanical polishing of metal gates according to claim 1, characterized in that, The corrosion inhibitor is one or more of sulfamethoxazole, sulfamethoxypyrimidine, sulfadimethoxypyrimidine, sulfaquinoxaline, and sulfa-5-methoxypyrimidine.

4. The cleaning solution after chemical mechanical polishing of metal gates according to claim 1, characterized in that, The mass ratio of the biotin polyethylene glycol derivative to the corrosion inhibitor is 10-16:

1.

5. The cleaning solution after chemical mechanical polishing of metal gates according to claim 1, characterized in that, The complexing agent is selected from organophosphonic acid derivatives.

6. The cleaning solution after chemical mechanical polishing of metal gates according to claim 1 or 5, characterized in that, The complexing agent is one or more of hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, ethylenediaminetetramethylene phosphonic acid, 1,3-propylidene diphosphonic acid, and 4-aminobutylphosphonic acid.

7. The cleaning solution after chemical mechanical polishing of metal gates according to claim 1, characterized in that, The pH of the cleaning solution after chemical mechanical polishing of the metal gate is 1-6.

8. The cleaning solution after chemical mechanical polishing of metal gates according to claim 1, characterized in that, The organic solvent is one or more selected from dimethyl sulfoxide, N,N-dimethylformamide, ethanol, methanol, and acetone.

9. A method for preparing the cleaning solution after chemical mechanical polishing of a metal gate according to any one of claims 1-8, characterized in that, Includes the following steps: S1: Weigh out the respective amounts of each component; S2: Add corrosion inhibitor, biotin polyethylene glycol derivative and organic solvent to a container, stir evenly, add complexing agent and ultrapure water, mix until all materials are completely dissolved, and prepare cleaning solution after chemical mechanical polishing of metal gate.

10. The application of the cleaning solution for chemical mechanical polishing of metal gates according to any one of claims 1-8 in the field of cleaning after chemical mechanical polishing of semiconductor chips.

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