CN113652316B

CN113652316B - Cleaning solution without quaternary ammonium base

Info

Publication number: CN113652316B
Application number: CN202110787696.7A
Authority: CN
Inventors: 孙秀岩; 王倩; 郭磊; 苏俊; 金徽
Original assignee: Zhangjiagang Anchu Technology Co ltd
Current assignee: Zhangjiagang Anchu Technology Co ltd
Priority date: 2021-07-13
Filing date: 2021-07-13
Publication date: 2022-07-08
Anticipated expiration: 2041-07-13
Also published as: WO2023284086A1; CN113652316A

Abstract

The invention relates to a cleaning solution without quaternary ammonium hydroxide, which is prepared from the following raw materials in percentage by mass: 1-20% of guanidine or a guanidine derivative, 1-20% of alkanolamine, 0.01-10% of nitrogen-containing heterocyclic compound metal corrosion inhibitor, and 60-99% of water. The cleaning solution does not contain quaternary ammonium hydroxide and easily-decomposed antioxidant metal inhibitor, has good environmental stability, has high-efficiency copper surface organic residue and abrasive particle removing capability, has low copper corrosion rate and copper surface roughness, and does not adsorb the copper surface.

Description

Cleaning solution free of quaternary ammonium hydroxide

Technical Field

The invention relates to the technical field of semiconductor manufacturing, in particular to a cleaning solution free of quaternary ammonium hydroxide.

Background

With the rapid development of very large scale integrated circuits, the integrated circuit manufacturing process becomes more and more complex and elaborate. In wafer fabrication, Chemical Mechanical Polishing (CMP) is the primary technique for planarization of semiconductor chips. The metal chemical mechanical polishing solution generally contains abrasive particles, a complexing agent, a metal corrosion inhibitor, an oxidizing agent and the like. The abrasive particles are mainly silica, alumina, ceria, etc. abrasive particles, etc. according to the application. During the CMP process, a large amount of fine polishing particles and chemical additives in the slurry, as well as debris stripped by wafer abrasion, may adhere to the wafer surface. Generally, the contaminants commonly found on the wafer after polishing are metal ions, organic compounds or polishing particles. If there is no effective cleaning procedure to remove the above-mentioned contaminants, the subsequent process will be affected and the yield and reliability of the device will be reduced. The cleaning process during or after the CMP process has become a key technology for successful application of CMP to semiconductor processes. Therefore, it is very necessary to remove metal ions, metal corrosion inhibitors and abrasive particles remaining on the wafer surface after the metal CMP process, to improve the hydrophilicity of the cleaned wafer surface, and to reduce surface defects.

U.S. patent No. 6,492,308 to Naghshineh et al discloses an alkaline cleaning solution for cleaning copper-containing integrated circuits, which is comprised of tetraalkylammonium hydroxide, a polar organic amine selected from monoethanolamine, and a corrosion inhibitor. The corrosion inhibitor is selected from antioxidants such as ascorbic acid and gallic acid.

US9481855B2 to Otake et al discloses an alkaline cleaning solution for cleaning copper-containing integrated circuits that is comprised of a tetraalkylammonium hydroxide (quaternary ammonium hydroxide), a polar organic amine, and a corrosion inhibitor selected from the group consisting of nitrogen-containing heterocyclic compounds such as xanthines.

Chinese patent CN101720352B to zhangpeng et al discloses an alkaline cleaning solution for cleaning copper-containing integrated circuits. The cleaning solution comprises at least one quaternary base, a corrosion inhibitor, and at least one organic amine. Wherein the corrosion inhibitor is selected from glucuronic acid, squaric acid, adenosine and derivatives thereof, flavonol and derivatives thereof, anthocyanin and derivatives thereof, and quercetin and derivatives thereof.

As semiconductor wafer processing has progressed, semiconductor processing has progressed to below 10 nm and to below 2 nm. The new planarization process still has many problems to be overcome due to the line width variation, for example, the copper conductive line width is in the nanometer range, the roughness of the metal surface of the wafer surface after the process treatment may be deteriorated, various polished organic matters and abrasive particles are more easily adsorbed on the copper surface, which makes the cleaning more difficult, thereby causing the deterioration of the electrical test and reliability test result of the copper wire wafer. Therefore, the cleaning composition for copper wire wafer is still required to effectively remove the contaminants remaining on the surface of the copper wire wafer and reduce the number of defects on the surface of the wafer.

In addition, quaternary ammonium bases, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and the like, are commonly used in cleaning solutions after copper chemical mechanical polishing. The use in semiconductor cleaning solutions is increasingly prohibited due to their higher toxicity. While less toxic choline has a strong odor due to its instability and inclusion of impurities. Therefore, there is a need for cleaning solutions that do not contain highly toxic or highly odorous quaternary ammonium hydroxides in semiconductor cleaning processes.

Furthermore, some antioxidant blockers such as ascorbic acid and kombutol are unstable in alkaline environments and decompose, resulting in a color change in the cleaning product. The decomposition products of the cleaning agent can affect the cleaning effect of the copper surface under different cleaning conditions based on the use environments of different cleaning products. Therefore, there is a need for a cleaning solution which does not contain quaternary ammonium hydroxide, can effectively clean the residue after chemical mechanical polishing of the copper surface, and is highly efficient.

Disclosure of Invention

The problem to be solved by the present invention is to provide a cleaning solution which contains no quaternary ammonium hydroxide, can effectively clean residues after chemical mechanical polishing of a copper surface, and further can effectively clean residues after chemical mechanical polishing of a copper surface with high efficiency. The invention relates to a cleaning solution without quaternary ammonium hydroxide, which is characterized by being prepared from the following raw materials in percentage by mass: 1 to 20 mass% of guanidine or a guanidine derivative, 1 to 20 mass% of alkanolamine, 0.01 to 10 mass% of nitrogen-containing heterocyclic compound metal corrosion inhibitor, and 60 to 99 mass% of water.

The cleaning solution disclosed by the invention does not contain quaternary ammonium hydroxide and easily-degradable antioxidant metal inhibitor, has good environmental stability, has high-efficiency removing capability of organic residues and grinding particles on the copper surface, has low corrosion rate and surface roughness of copper, and cannot adsorb the copper surface.

Further, the guanidine or guanidine derivative is selected from one or more of guanidine, 1,1,3, 3-tetramethylguanidine, arginine, 2-tert-butyl-1, 1,3, 3-tetramethylguanidine, 2- (4-tolyl) -1,1,3, 3-tetramethylguanidine, biguanide, metformin, phenformin, proguanil, buformin, 1- (o-tolyl) biguanide; the mass percentage of the guanidine or the guanidine derivative is selected from 1-20%, 1-10%, 5-15% and 5-10%; preferably 5-15%, more preferably 5-10%.

Further, the guanidine is guanidine and 1,1,3, 3-tetramethyl guanidine; the guanidine is 1,1,3, 3-tetramethyl guanidine.

Further, the alkanolamine is selected from one or more of monoethanolamine, diethanolamine, diglycolamine, methylethanolamine, triethanolamine, isopropanolamine, methyldiethanolamine, diethylaminoethanol, 2-amino-2-methyl-1-propanol, N- (aminoethyl) ethanolamine, 2-amino-1-butanol, isobutanolamine, N-dimethyl-2-aminoethanol, and hydroxyethylethylenediamine; the alkanolamine is monoethanolamine and diglycolamine; the mass percentage of the alkanolamine is selected from 1-20%, 1-10%, 5-15%, 3-10% and 3-15%; preferably 1-20%, more preferably 3-10%. In practice, monoethanolamine and diglycolamine are preferred, and diglycolamine is more preferred.

Further, the nitrogen-containing heterocyclic compound metal corrosion inhibitor is selected from one or more of purine, adenine, guanine, hypoxanthine, xanthine, theophylline, theobromine, caffeine, uric acid, isoguanine, adenosine, derivatives of the above compounds, and the like; the nitrogen-containing heterocyclic compound metal corrosion inhibitor is guanine and adenine; the nitrogen-containing heterocyclic compound metal corrosion inhibitor is guanine; the mass percent of the nitrogen heterocyclic compound metal corrosion inhibitor is selected from one of 0.1-10%, 0.1-8%, 0.1-5% and 0.1-2.5%; preferably 0.1 to 5%, more preferably 0.5 to 2.5%. In practice, guanine and adenine are preferred, and guanine is more preferred.

In practice, the readily decomposable antioxidant comprises one or more selected from ascorbic acid, 3,4, 5-trihydroxybenzoic acid, catechol, theophylline and derivatives thereof; quaternary ammonium bases include tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, choline, tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, benzyltrimethyl ammonium hydroxide, ethyltrimethyl ammonium hydroxide, and diethyldimethyl ammonium hydroxide.

Further, the mass percentage of the water is selected from one of 60-99%, 60-90%, 70-95%, 80-95% and 80-90%; preferably 70-95%, more preferably 80-95%.

Further, the pH value of the cleaning solution is greater than 8; preferably pH >11, more preferably pH > 13.

In practice, no oxidizing agent, e.g., hydrogen peroxide, abrasive particles, inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, inorganic bases, potassium hydroxide, sodium hydroxide, aqueous ammonia, surfactants, halides such as fluorides, chlorides, bromides, sulfur-containing compounds, various organic solvents, metal-containing compounds, are included in the cleaning solution.

Further, the cleaning solution may contain a metal corrosion inhibitor which is other nitrogen-containing heterocyclic compound; the other metal corrosion inhibitor is one or more of other nitrogen-containing heterocyclic compounds selected from imidazole, phenyl azide, benzimidazole, benzothiazole, urea and derivatives of the compounds; the metal corrosion inhibitor is one of other nitrogen-containing heterocyclic compounds with the mass percentage of 0.001-5%, 0.01-2%, 0.05-2% and 0.1-1.5%; preferably 0.01-2%, more preferably 0.1-1.5%. In practice, the metal corrosion inhibitor is other nitrogen-containing heterocyclic compound that may include a material selected from the group consisting of: benzotriazole (BTA), 1, 2, 4-Triazole (TAZ), 5 aminotetrazole (ATA), 1-hydroxybenzotriazole, 5-amino-1, 3, 4-thiadiazole-2-thiol, 3-amino-1H-1, 2, 4-triazole, 3, 5-diamino-1, 2, 4-triazole, tolyltriazole, 5-phenylbenzotriazole, 5-nitrobenzotriazole, 3-amino-5-mercapto-1, 2, 4-triazole, 1-amino-1, 2, 4-triazole, 2- (5-aminopentyl) -benzotriazole, 1-amino-1, 2, 3-triazole, 1-amino-5-methyl-1, 2, 3-triazole, 3-mercapto-1, 2, 4-triazole, 3-isopropyl-1, 2, 4-triazole, 5-phenylthiol-benzotriazole, and the like.

Further, when the cleaning solution is used, the cleaning solution is firstly diluted with water, and the dilution ratio is 1: 1 to 1: 200, preferably 1: 10 to 1: 100, more preferably 1: 20 to 1: 60, adding a solvent to the mixture; the cleaning solution can be used for cleaning the ground copper semiconductor metal substrate surface; the material of the metal substrate can be selected from one or more of copper, tantalum nitride, titanium and titanium nitride.

In practice, the washing temperature is between 20 and 60 ℃ and preferably between 20 and 30 ℃.

Further, the cleaning solution can be used for cleaning a wafer in a cleaning machine or cleaning the wafer on a polishing disk after polishing is finished. The invention can be used for cleaning the planarized wafer surface on a chemical mechanical planarization machine, and can also be used for cleaning the planarized wafer surface on an independent cleaning machine.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a graph of the effect of different inhibitors on copper corrosion rate for a cleaning solution of the present invention that does not contain a quaternary ammonium hydroxide;

FIG. 2 is a graph of the color change of a sample of a cleaning solution of the present invention without a quaternary ammonium hydroxide at 55 ℃ aging;

FIG. 3 is a graph of the change in roughness of a copper surface after cleaning with a cleaning solution of the present invention that does not contain a quaternary ammonium hydroxide;

FIG. 4 is a graph showing the effect of monoethanolamine on copper corrosion rate of a cleaning solution of the present invention without quaternary ammonium hydroxide;

FIG. 5 is a graph of the effect of different combinations of inhibitors on copper corrosion rate for a cleaning solution of the present invention without quaternary ammonium hydroxide;

FIG. 6 is a graph showing the effect of component concentration on copper corrosion rate for a cleaning solution of the present invention that does not contain quaternary ammonium hydroxide;

FIG. 7 is a graph of the open circuit potential change on benzotriazole adsorption of different cleaning solution samples of a cleaning solution without quaternary ammonium hydroxide in accordance with the present invention;

FIG. 8 is a graph of the effect of different cleaning solution sample dilution ratios on benzotriazole adsorbed copper surface open circuit potential versus time for a cleaning solution of the present invention without quaternary ammonium hydroxide;

FIG. 9 is an electrochemical impedance spectrum of benzotriazole-adsorbed copper surfaces from different cleaning solution samples of a cleaning solution of the present invention without quaternary ammonium hydroxide;

FIG. 10 is an AFM image of the cleaning effect of a cleaning solution of the present invention on a copper surface without quaternary ammonium hydroxide.

Detailed Description

The present invention will be further described in detail with reference to the following specific examples:

The cleaning solution disclosed by the invention does not contain quaternary ammonium hydroxide and easily-decomposed antioxidant metal inhibitor, has good environmental stability, has high-efficiency copper surface organic residue and abrasive particle removing capability, has low copper corrosion rate and copper surface roughness, and does not adsorb the copper surface.

In actual operation, the cleaning solution does not contain quaternary ammonium hydroxide and easily-decomposed antioxidant, so that the toxicity of the cleaning solution and the stability of the cleaning solution are reduced; the cleaning solution is used for cleaning the polished wafer containing metal, so that the residues of grinding particles, metal ions and the like on the surface of the polished wafer can be removed, the roughness of the metal surface is reduced, the surface defect after cleaning is reduced, and the metal corrosion possibly generated in the process of waiting for the next working procedure of the wafer can be prevented.

Further, the nitrogen-containing heterocyclic compound metal corrosion inhibitor is selected from one or more of purine, adenine, guanine, hypoxanthine, xanthine, theophylline, theobromine, caffeine, uric acid, isoguanine, adenosine, derivatives of the above compounds, and the like; the nitrogen-containing heterocyclic compound metal corrosion inhibitor is guanine and adenine; the nitrogen-containing heterocyclic compound metal corrosion inhibitor is guanine; the mass percentage of the nitrogen heterocyclic compound metal corrosion inhibitor is selected from one of 0.1-10%, 0.1-8%, 0.1-5% and 0.1-2.5%; preferably 0.1 to 5%, more preferably 0.5 to 2.5%. In practice, guanine and adenine are preferred, and guanine is more preferred.

Further, when in use, the cleaning solution is firstly diluted with water, and the dilution ratio is 1: 1 to 1: 200, preferably 1: 10 to 1: 100, more preferably 1: 20 to 1: 60, adding a solvent to the mixture; the cleaning solution can be used for cleaning the ground copper semiconductor metal substrate surface; the material of the metal substrate can be selected from one or more of copper, tantalum nitride, titanium and titanium nitride.

In practical operation, the concentration of the cleaning solution of the present invention, generally to save the production, transportation and storage costs, will usually be prepared to provide a higher concentration of cleaning solution, and then diluted with ultrapure water at the use end by about 1: 1-1: used after 200 times. Under special requirements, the cleaning composition stock solution with higher concentration can be directly used for cleaning the wafer.

In practice, the cleaning solution of the present invention can be used at room temperature, and the cleaning composition can be contacted with the metal-containing semiconductor wafer for an effective period of time, so as to effectively remove the residual contaminants on the wafer surface, and maintain the copper wire with a better surface roughness. Generally, longer contact times (e.g., 1-3 minutes) are required when lower concentrations are used, and shorter contact times (e.g., less than 1 minute) are required when higher concentrations are used. In practical use, the user can find the optimal concentration of the cleaning solution and the optimal contact time by the required process.

In actual operation, the raw materials of the components are mixed. The temperature of mixing was room temperature. After mixing, the method further comprises shaking and filtering operations. In the cleaning liquid, the sum of the mass fractions of the components is 100%, and the amount of water is calculated to complement the sum of the mass fractions of the components to 100%. Before the corrosion rate measurement and the electrochemical measurement, unless otherwise specified, the dilution ratio of the cleaning liquid and water was 1: 60. all measurements were performed at room temperature, 25 ℃, with a blank wafer of 100 nm copper used for all measurements.

The benzotriazole on the surface of the copper wafer is removed by electrochemical measurement, and the open-circuit potential and the electrochemical impedance spectrogram of the surface of the electrode are measured through a RST5000 electrochemical workstation. Firstly, a copper wafer electrode is soaked in an aqueous solution containing 2% benzotriazole for 1-3 minutes, and is soaked in a diluted cleaning solution sample for 1-5 minutes after being cleaned by deionized water, and then is cleaned by the deionized water and is dried by nitrogen. The treated copper wafer is put into an inert electrolyte, and the open circuit potential and the electrochemical impedance spectrogram of the surface of the electrode are observed under the condition of no stirring. The reference electrode used was an Ag/AgCl reference electrode, the counter electrode used was a carbon rod, and the copper wafer was the working electrode.

In the corrosion rate measurement, the copper wafers were cleaned in 500 ml of cleaning solution using magnetic stirring at 400rpm for 5-20 minutes. The etch rate results from the thickness variation of the copper before and after cleaning. The thickness of the copper was measured by an instrument RTS-9 dual electrical measurement four probe tester.

The surface roughness of the copper is measured by an atomic force microscope FM-Nanoview1000AFM

In the experiment of cleaning the surface of the metallic copper, the metallic copper wafer is firstly placed in a commercial grinding fluid which can be used for the chemical mechanical grinding of the surface of the metallic copper for 1 to 5 minutes, and then is washed by clean water and dried by nitrogen. Then the metal copper wafer with the surface stained with the organic matters and the grinding ions in the grinding fluid is stirred and cleaned for 1-5 minutes at the room temperature and 400rpm in the cleaning fluid. Then the mixture is washed by clean water and dried by nitrogen. The cleaning effect of the metallic copper surface was evaluated by AFM imaging of the metallic copper surface.

As shown in FIG. 1,1, 1,3, 3-tetramethylguanidine as a pH adjuster, diglycolamine as a complexing agent, and commonly used copper inhibitors such as ascorbic acid and benzotriazole, all reduce the corrosion rate of copper. The newly added inhibitors uric acid, xanthine, theophylline, theobromine, guanine, hypoxanthine and adenine all influence the corrosion rate of copper. Wherein xanthine, guanine and adenine reduce the corrosion rate of copper, and guanine and adenine reduce the corrosion of copper more obviously, better than benzotriazole and ascorbic acid.

As shown in fig. 2, the test results showed that sample 2 containing ascorbic acid and sample 5 containing theophylline showed a significant color change under the condition of 55 ℃. Indicating that both inhibitors changed over time. And the other inhibitors have no obvious color change and are colorless.

As shown in fig. 3, the test results show the change in the roughness of the copper surface after cleaning of the resulting

samples

1, 2, 7, 9. Sample 1, which did not contain any inhibitor, showed a higher copper roughness. The ascorbic acid inhibitor improves the surface roughness of copper. And guanine and adenine significantly reduce the roughness of the copper surface.

As shown in fig. 4, the test results show the effect of monoethanolamine as a complexing agent on the corrosion rate of copper. Monoethanolamine significantly increases the corrosion rate of copper compared to diglycolamine in fig. 1. Ascorbic acid, guanine and adenine all inhibit the corrosion rate of copper.

As shown in fig. 5, the test results demonstrate that different combinations of suppressors can have an effect on the corrosion rate of copper. The addition of guanine or adenine to the ascorbic acid, gallic acid or catechol component may further reduce the corrosion rate of copper. The effect of the guanine or adenine blocker can be seen more clearly in gallic acid and catechol, the addition of which significantly reduces the corrosion rate of copper.

As shown in fig. 6, increasing the concentration of 1,1,3, 3-tetramethylguanidine to 12% or increasing the concentration of diglycolamine significantly increased the copper corrosion rate. Whereas an increase in guanine concentration to 4% significantly increases the corrosion rate of copper.

As shown in fig. 7, the test results show that the open circuit potential of copper in the inert electrolyte solution does not change significantly with the copper surface adsorbed by benzotriazole, indicating that benzotriazole cannot be desorbed from the copper surface quickly. The potential of the copper surface on which benzotriazole is adsorbed after being cleaned by the

cleaning solution samples

7 and 9 is quickly reduced to the same open circuit potential as that of the copper surface without any adsorption, which indicates that no benzotriazole is adsorbed on the copper surface after being cleaned by the cleaning solution samples, and no guanine or adenine is adsorbed on the copper surface by the cleaning solution samples.

As shown in fig. 8, the test results show that the open circuit potentials of both sample 7 and sample 9 reach the open circuit potential of the blank copper surface under different dilution ratios, indicating that both samples can effectively remove the benzotriazole adsorbed on the copper surface and do not generate any inhibitor adsorption on the copper surface.

The electrochemical impedance spectroscopy shown in fig. 9 confirms that

samples

7 and 9, as evidenced by the observation of the copper open circuit potential, are effective in removing benzotriazole adsorbed on the copper surface and do not themselves produce adsorption on the copper surface. As can be seen from fig. 2, adsorption of benzotriazole produced a large impedance to the copper surface, while the impedance of the copper surface after cleaning of the adsorbed copper surface of benzotriazole was similar to that of the blank copper surface for

samples

7 and 9.

As shown in fig. 10, the cleaning effect of the copper surface indicates that after the copper surface is soaked in the polishing solution containing the polishing particles, the polishing particles in the polishing solution are easily adhered to the metal copper surface and are not easily washed clean by water, after the cleaning solution sample 7 is cleaned, the polishing particles on the copper surface are completely removed, and the roughness of the copper surface is not significantly different from that of the blank copper surface, which indicates that the sample 7 can effectively clean the polishing particles on the copper surface and protect the metal copper surface.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The cleaning solution free of quaternary ammonium base is characterized by being prepared from the following raw materials in percentage by mass: 1-20% of guanidine or guanidine derivative, 1-20% of alkanolamine, 0.01-10% of nitrogen-containing heterocyclic compound metal corrosion inhibitor, 60-99% of water and 0.001-5% of metal corrosion inhibitor; the guanidine derivative is selected from one or more of 1,1,3, 3-tetramethylguanidine, arginine, 2-tert-butyl-1, 1,3, 3-tetramethylguanidine, 2- (4-tolyl) -1,1,3, 3-tetramethylguanidine, biguanide, metformin, phenformin, proguanil, buformin and 1- (o-tolyl) biguanide; the alkanolamine is selected from one or more of monoethanolamine, diethanolamine, diglycolamine, methylethanolamine, triethanolamine, isopropanolamine, methyldiethanolamine, diethylaminoethanol, 2-amino-2-methyl-1-propanol, N- (aminoethyl) ethanolamine, 2-amino-1-butanol, isobutanolamine, N-dimethyl-2-aminoethanol, and hydroxyethylethylenediamine; the metal corrosion inhibitor of the nitrogen-containing heterocyclic compound is selected from one or more of purine, adenine, guanine, hypoxanthine, xanthine, theophylline, theobromine, caffeine, uric acid, isoguanine, adenosine and derivatives of the above compounds; the metal corrosion inhibitor is selected from one or more of imidazole, phenyl azide, benzimidazole, benzothiazole, urea and derivatives of the above compounds.

2. The quaternary ammonium hydroxide-free cleaning solution according to claim 1, wherein: the mass percent of the nitrogen-containing heterocyclic compound metal corrosion inhibitor is 0.1-10%.

3. The quaternary ammonium hydroxide-free cleaning solution according to claim 1, wherein: the mass percentage of the water is 60-90%.

4. The quaternary ammonium hydroxide-free cleaning solution according to claim 1, wherein: the pH value of the cleaning solution is more than 8.

5. A quaternary ammonium hydroxide-free cleaning solution according to any one of claims 1 to 4, wherein: when the cleaning solution is used, the cleaning solution is firstly diluted with water, and the dilution ratio is 1: 1 to 1: 200 of a carrier; the cleaning solution is used for cleaning the ground copper semiconductor metal substrate surface; the material of the metal substrate is selected from copper.

6. A quaternary ammonium hydroxide-free cleaning solution according to any one of claims 1 to 4, wherein: the cleaning liquid is used for cleaning the wafer in a cleaning machine or cleaning the wafer on a polishing disk after polishing is finished.