A semiconductor cobalt process CMP post-cleaning liquid, its preparation method and application

Abstract

The present invention provides a semiconductor cobalt process post-CMP cleaning liquid, a preparation method and application thereof, and the semiconductor cobalt process post-CMP cleaning liquid comprises the following components in weight proportion: 1-15 parts of cyclodextrin PEG amino acid compounds; 0.1-1 parts of corrosion inhibitors; 5-15 parts of phosphate compounds; 10-20 parts of organic weak bases; 60-80 parts of ultrapure water. The present invention also discloses a preparation method of the semiconductor cobalt process post-CMP cleaning liquid, and its application in the field of semiconductor chip cleaning. The semiconductor cobalt process post-CMP cleaning liquid of the present invention does not contain strong alkalis and strong acids, and can still effectively remove pollutants such as organic residues and particles, and has no corrosion to the chip. The semiconductor cobalt process post-CMP cleaning liquid of the present invention has no special requirements for the cleaning process. Only under the process of immersion, the organic pollutants and various particles adhered to the chip can be completely eluted, and only pure water rinsing is required later, and no dirt remains after water washing.

Description

Technical Field

[0001] The present invention relates to chip cleaning liquid technology, and in particular to a semiconductor cobalt process CMP post-cleaning liquid, and a preparation method and application thereof. Background Art

[0002] As advanced semiconductor manufacturing technology develops towards single-digit nanometer processes, the copper wires of the current process cannot meet the needs of single-digit nanometer processes due to insufficient conductivity, which hinders the development of advanced processes. Due to the excellent physical and chemical properties of cobalt, it is inevitable that it will replace Cu and become the next generation of very large-scale integrated circuit interconnect metal materials.

[0003] However, cobalt has an active chemical property. Co has a high corrosion rate in acidic polishing liquid. Co is accelerated to corrode as an anode, and inhibitors need to be added to alkaline polishing liquid to avoid excessive corrosion and pitting. In industrial production, benzotriazole (BTA) is widely used in Co interconnect layer CMP alkaline polishing liquid due to its good anti-corrosion effect and low price. After polishing, BTA will form organic residues on the surface of the metal interconnect layer, preventing the cleaning solution from reaching the Co surface, resulting in inability to thoroughly clean. In addition, these organic residue films are also highly hydrophobic, leading to drying problems, affecting subsequent layer deposition, and ultimately reducing device performance. Therefore, removing pollutants such as organic residues on the wafer surface after the Co process CMP process is crucial for post-CMP cleaning of the Co process.

[0004] Traditional metal post-CMP cleaning solutions are mainly composed of strong organic acids such as citric acid, strong organic bases such as tetramethylammonium hydroxide (TMAH) and tetraethylammonium hydroxide (TEAH), or strong inorganic bases such as ammonium hydroxide (NH4OH). After cleaning, the surface roughness of the wafer will increase, causing wafer corrosion.

[0005] Therefore, it is of great significance to develop a post-CMP cleaning solution for semiconductor Co process that does not contain strong alkali or strong acid. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the current cleaning solution containing strong alkali and strong acid easily causes the surface roughness of the wafer to increase and corrode, and to propose a cleaning solution after CMP of a semiconductor cobalt process, which does not contain strong alkali and strong acid, does not corrode the chip, and can still effectively remove pollutants such as organic residues and particles. The cleaning solution after CMP of a semiconductor cobalt process of the present invention has no special requirements for the cleaning process, and can completely wash away the organic pollutants and various particles adhered to the chip only under the process of immersion, and only needs to be rinsed with pure water afterwards, and no dirt remains after washing.

[0007] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a semiconductor cobalt process CMP post-cleaning liquid, comprising the following components in weight proportions:

[0009] 1-15 parts of cyclodextrin PEG amino acid compound;

[0010] Corrosion inhibitor 0.1-1 part;

[0011] 5-15 parts of phosphate compound;

[0012] 10-20 parts of organic weak base;

[0013] 60-80 parts of ultrapure water.

[0014] Furthermore, the cyclodextrin PEG amino acid compound is one or more of cyclodextrin-polyethylene glycol-glycine, cyclodextrin-polyethylene glycol-histidine, cyclodextrin-polyethylene glycol-glutamic acid, cyclodextrin-polyethylene glycol-lysine and cyclodextrin-polyethylene glycol-threonine.

[0015] Furthermore, the cyclodextrin PEG amino acid compound is preferably one or more of cyclodextrin-polyethylene glycol-glutamic acid, cyclodextrin-polyethylene glycol-lysine and cyclodextrin-polyethylene glycol-threonine.

[0016] Furthermore, the cyclodextrin PEG amino acid compound is most preferably cyclodextrin-polyethylene glycol-threonine.

[0017] Further, the cyclodextrin PEG amino acid compound is 5-10 parts;

[0018] The cyclodextrin PEG amino acid compound of the present invention has both cleaning function and solubilizing and dispersing function. The cavity structure of cyclodextrin and amino acid in the cyclodextrin PEG amino acid compound can chelate Co 2+ , dissolving the oxides attached to the Co surface, and then removing the organic residues and particles on the Co surface, achieving the purpose of cleaning. At the same time, cyclodextrin PEG amino acid compounds can remove other metal ions on the wafer together, ensuring the yield rate of subsequent production. In addition, the polyethylene glycol group contained in the cyclodextrin PEG amino acid compounds will increase the hydrophilicity of the substance, improve its solubility, and facilitate its diffusion on the metal surface, making the cleaning liquid clean the metal surface more evenly, and will not cause pitting, spotting, etc. due to uneven dispersion of cyclodextrin PEG amino acid compounds.

[0019] Furthermore, the corrosion inhibitor is an oxime acid compound.

[0020] Furthermore, the corrosion inhibitor is preferably one or more of crown ether hydroxamic acid, L-glutamic acid γ-monohydroxamic acid and suberoxime.

[0021] Furthermore, the corrosion inhibitor is more preferably crown ether hydroxamic acid.

[0022] Further, the corrosion inhibitor is 0.3-0.8 parts;

[0023] The corrosion inhibitor of the present invention can cooperate with cyclodextrin PEG amino acid compounds to play a corrosion inhibition effect. The crown ether structure in the corrosion inhibitor crown ether hydroxamic acid contains multiple O atoms, and the cyclodextrin in the cyclodextrin PEG amino acid compound contains a large number of hydroxyls, and the two can be combined to form hydrogen bonds, thereby forming a large hydrogen bond network. At the same time, the oxime acid in the corrosion inhibitor can also be coordinated with the metal ion, and the large hydrogen bond network and coordination promote each other, adsorbing and forming a film on the metal surface, so that the corrosive substance cannot contact the metal surface, inhibiting the corrosion of the metal, and avoiding the redeposition of metal ions, and improving the cleaning efficiency. At the same time, the corrosion inhibitor and the cyclodextrin PEG amino acid compound can be evenly dispersed in the system with the help of phosphate compounds, so that the corrosion inhibitor and the cyclodextrin PEG amino acid compound are evenly adsorbed on the metal surface, and the wafer after cleaning has complete protection, avoiding the situation of pitting on the wafer surface after cleaning.

[0024] Furthermore, the phosphate compound is alkylphenol polyoxyethylene ether phosphate and / or fatty alcohol polyoxyethylene ether phosphate.

[0025] Furthermore, the alkylphenol polyoxyethylene ether phosphate is one or more of phosphate ester TXP-10, phosphate ester APE-10P and phosphate ester OP-10P.

[0026] ‌‌Furthermore, the fatty alcohol polyoxyethylene ether phosphate is AEO-3P‌ and‌‌ or AEO-9P.

[0027] Furthermore, the phosphate compound is preferably fatty alcohol polyoxyethylene ether phosphate.

[0028] Furthermore, the phosphate compound is more preferably AEO-9P.

[0029] Further, the phosphate compound is 8-12 parts;

[0030] The phosphate compounds of the present invention can change the surface tension of the liquid, change its contact angle on the wafer, increase the contact area between the liquid and the wafer, and fully wet the entire wafer, thereby improving the cleaning effect of the cyclodextrin PEG amino acid compounds and the corrosion inhibition effect of the corrosion inhibitor.

[0031] Furthermore, the organic weak base is one or more of pyridine, imidazole, 1-methylimidazole, butyramide, monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, DL-aminopropanol, 2-(methylamino)ethanol, (S)-(+)-2-amino-1-butanol and N-(2-hydroxyethyl)ethylenediamine.

[0032] Furthermore, the organic weak base is preferably one or more of pyridine, imidazole, 1-methylimidazole, and butanamide.

[0033] Furthermore, the organic weak base is more preferably 1-methylimidazole.

[0034] Furthermore, the organic weak base is 12-16 parts.

[0035] The organic weak base selected in the present invention can form a conjugate acid-base system in water, making the ionic compound more easily ionized, facilitating further combination of the cyclodextrin PEG amino acid compound with the metal ion and thus improving the cleaning efficiency.

[0036] Furthermore, the ultrapure water is deionized water with a resistance ≥ 18 MΩ.

[0037] Furthermore, the ultrapure water is 65-75 parts.

[0038] Another object of the present invention is to disclose a method for preparing a cleaning solution after CMP in a semiconductor cobalt process, comprising the following steps:

[0039] Weigh out the respective amounts of each component;

[0040] All components are added into a container and mixed until all materials are completely dissolved to prepare a semiconductor cobalt process post-CMP cleaning solution.

[0041] Another object of the present invention is to disclose an application of a semiconductor cobalt process post-CMP cleaning liquid in the field of cleaning semiconductor chips.

[0042] Furthermore, the semiconductor cobalt process post-CMP cleaning solution is particularly suitable for cleaning cobalt wafers.

[0043] Furthermore, a method for cleaning a cobalt wafer using a semiconductor cobalt process post-CMP cleaning solution comprises the following steps:

[0044] Step 1, diluting the post-CMP cleaning solution with ultrapure water by 10-100 times to obtain a diluted cleaning solution, and using the diluted cleaning solution to soak a cobalt wafer at room temperature to obtain a soaked cobalt wafer;

[0045] Step 2: Rinse the soaked cobalt wafer in ultrapure water to complete the cleaning of the cobalt wafer.

[0046] Furthermore, in step 1, the soaking time is 50-200s.

[0047] Furthermore, in step 2, the number of flushing times is greater than or equal to three times.

[0048] The semiconductor cobalt process post-CMP cleaning liquid, its preparation method and application of the present invention have the following advantages compared with the prior art:

[0049] 1) The corrosion inhibitor of the present invention is compounded with a cyclodextrin PEG amino acid compound. The corrosion inhibitor structure contains multiple O atoms, and the cyclodextrin PEG amino acid compound contains a large number of hydroxyl groups. The two can combine to form hydrogen bonds, thereby forming a large hydrogen bond network. At the same time, the oxime acid in the corrosion inhibitor can also coordinate with the metal ions. The large hydrogen bond network and the coordination effect promote each other, adsorbing on the metal surface to form a film, isolating the corrosive substances from the metal surface, and inhibiting the corrosion of the metal. In addition, the corrosion inhibitor and the cyclodextrin PEG amino acid compound can be evenly dispersed in the system with the help of phosphate compounds, so that the corrosion inhibitor and the cyclodextrin PEG amino acid compound are evenly adsorbed on the metal surface, which has complete protection for the cleaned wafer and avoids pitting on the wafer surface after cleaning.

[0050] 2. The cavity structure of cyclodextrin in the cyclodextrin PEG amino acid compound selected by the present invention and the hydroxyl and amino groups in the amino acid can chelate Co 2+ , dissolve the oxide attached to the Co surface, and then remove the organic residues and particles on the Co surface to achieve the purpose of cleaning. At the same time, the cyclodextrin PEG amino acid compound can remove other metal ions on the wafer together to ensure the yield rate of subsequent production. In addition, the polyethylene glycol group contained in the cyclodextrin PEG amino acid compound will increase the hydrophilicity of the substance, improve the solubility, and facilitate its diffusion on the metal surface, so that the cleaning liquid cleans the metal surface more evenly, and will not cause pitting, spotting, etc. due to the uneven dispersion of the cyclodextrin PEG amino acid compound, so that the cyclodextrin PEG amino acid compound of the present invention has the functions of cleaning, solubilization, and dispersion.

[0051] 3. The semiconductor cobalt process post-CMP cleaning solution of the present invention does not need to add organic strong acids such as citric acid or organic strong bases such as tetramethylammonium hydroxide (TMAH). The special structure of cyclodextrin PEG amino acid compounds and the synergistic effect between the functional agent and the corrosion inhibitor chelate metal ions to remove organic residues and particles. Therefore, even if the semiconductor cobalt process post-CMP cleaning solution of the present invention does not contain organic strong acids and strong bases, it can still achieve the effect of cleaning organic residues and particles, and will not damage the wafer surface. It only needs to be rinsed with pure water, which is harmless to the environment and human body.

[0052] 4. The cleaning solution after CMP in the semiconductor cobalt process of the present invention has no corrosion to the chip, has no special requirements for the cleaning process, and does not require ultrasonic treatment. Only under the process of immersion, the organic pollutants and various particles adhering to the chip can be completely washed away, and only pure water rinsing is required afterwards, and no dirt remains after washing.

[0053] Therefore, the semiconductor cobalt process post-CMP cleaning solution of the present invention has very good application prospects and large-scale industrial promotion potential in the field of semiconductor chip cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a microscope picture of a Co wafer cleaned with the cleaning solution of Example 1, magnified 100 times.

[0055] Figure 2 This is a microscope picture of a Co wafer cleaned with the cleaning solution of Comparative Example 1, magnified 100 times.

[0056] Figure 3 This is a microscope picture of a Co wafer cleaned with the cleaning solution of Comparative Example 2, magnified 100 times. DETAILED DESCRIPTION

[0057] The present invention is further described below with reference to the examples. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0058] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0059] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0060] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0061] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0062] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0063] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0064] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0065] Examples 1-6

[0066] Examples 1-6 disclose a variety of semiconductor cobalt process post-CMP cleaning solutions, the components and weight ratios of which are shown in Table 1. The preparation method is as follows: weigh each component in its respective amount; add all components into a container and mix until all materials are completely dissolved to prepare a semiconductor cobalt process post-CMP cleaning solution.

[0067] Table 1 Components and weight ratios of the cleaning solution after CMP in the semiconductor cobalt process of Examples 1-6

[0068]

[0069] Comparative Examples 1-4

[0070] Comparative Examples 1-4 disclose a variety of cleaning solutions, the components and weight ratios of which are shown in Table 2. The preparation methods are the same as those of Example 1.

[0071] Table 2 Components and weight ratios of cleaning solutions in comparative examples 1-4

[0072]

[0073] The cleaning solutions of Examples 1-6 and Comparative Examples 1-4 were tested respectively, and the test results are shown in Table 3.

[0074] Table 3 Test results

[0075]

[0076] Based on the data in Table 3, after the chip is cleaned with the semiconductor cobalt process post-CMP cleaning solution of Examples 1-6, the chip corrosion rate is less than or equal to 1Å / min, almost no corrosion, and the contact angle after cleaning is less than 48°, indicating that there is no residue on the Co surface, and the surface roughness of the wafer is small after cleaning with the cleaning solution of Examples 1-6.

[0077] Compared with Example 1, Comparative Example 1 did not add cyclodextrin PEG amino acid compounds, resulting in incomplete cleaning of organic residues on the Co surface after cleaning and increased corrosion rate of the Co surface;

[0078] In Comparative Example 2, no corrosion inhibitor was added, resulting in an increase in the corrosion rate of Co after cleaning, residual organic matter on the surface, and incomplete cleaning;

[0079] Comparative Example 3 uses β-cyclodextrin polyethylene glycol cyclophosphamide as a functional agent, which results in an increase in the corrosion rate of Co after cleaning, and organic matter remains on the surface of Co after cleaning, and the cleaning is not complete;

[0080] Comparative Example 4 uses benzohydroxamic acid as a corrosion inhibitor, which results in an increased corrosion rate, residual organic matter on the surface, and incomplete cleaning.

[0081] Figure 1 This is a microscope picture of a Co wafer cleaned with the cleaning solution of Example 1, magnified 100 times. Figure 1 It can be seen that the Co wafer is substantially free of corrosion after being cleaned with the cleaning solution of Example 1. Figure 2 This is a microscope picture of a Co wafer cleaned with the cleaning solution of Comparative Example 1, magnified 100 times. Figure 2 It can be seen that the Co wafer is slightly corroded. Figure 3 This is a microscope picture of a Co wafer cleaned with the cleaning solution of Comparative Example 2, magnified 100 times. Figure 3 It can be seen that the Co wafer is severely corroded. Figure 1-3 By comparison, it can be seen that the surface of the Co wafer cleaned with the cleaning solution of Example 1 is basically not corroded, while the surfaces of the Co wafers cleaned with the cleaning solutions of Comparative Examples 1 and 2 are corroded to varying degrees, which proves that the cleaning solution prepared by the method of the present invention has low corrosion to the wafer and is significantly better than the cleaning solution of the comparative example.

[0082] About performance testing and description:

[0083] Performance 1 The test method for metal corrosion is:

[0084] The cobalt wafer was cut into 2cm×2cm square pieces, treated with isopropanol at room temperature for 5min, washed with pure water, dried with nitrogen, and the front film thickness was measured with a four-point probe. The cleaning solution was diluted 50 times with ultrapure water to obtain a diluted cleaning solution, and the cobalt wafer was immersed in 30ml of the diluted cleaning solution for 5h for corrosion. After 5h, the cobalt wafer was taken out, washed with pure water, dried with nitrogen, and the rear film thickness was measured with a four-point probe, and then a microscope picture was taken for comparison. The corrosion rate calculation formula is: corrosion rate (Å / min) = (front film thickness-rear film thickness) / immersion time.

[0085] The test method for performance 2 cleaning effect is:

[0086] In order to characterize the hydrophilicity of the Co wafer surface during post-Co-CMP cleaning, a contact angle meter was used for testing. Deionized water was dropped on the Co wafer surface, and the angle was analyzed using a contact angle meter to determine the hydrophilicity and hydrophobicity of the Co wafer surface. The removal of residual BTA was determined based on the hydrophilicity and hydrophobicity of the Co wafer surface.

[0087] The surface of a fresh Co wafer is hydrophilic (the contact angle of a fresh Co wafer is 48°; a value lower than this indicates that there is no residue on the Co surface, and a value higher than this indicates that there is residue on the Co surface). The contact angle of deionized water on the surface of the Co wafer is small. When a BTA film exists on the surface of the Co wafer, the surface of the Co wafer is hydrophobic, and the contact angle of deionized water on the surface of the Co wafer is large.

[0088] The test method for performance 3 roughness is:

[0089] The above solution was diluted 50 times with ultrapure water to prepare a diluted cleaning solution, and then the cobalt crystal original piece was placed in it and immersed for 5 hours. After rinsing with deionized water and drying with nitrogen, the roughness Ra value was measured by AFM.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A semiconductor cobalt process post-CMP cleaning solution, characterized in that: The composition includes the following components in weight ratio: 1-15 parts of cyclodextrin PEG amino acid compound; Corrosion inhibitor 0.1-1 part; 5-15 parts of phosphate compound; 10-20 parts of organic weak base; 60-80 parts of ultrapure water; The cyclodextrin PEG amino acid compound is one or more of cyclodextrin-polyethylene glycol-glycine, cyclodextrin-polyethylene glycol-histidine, cyclodextrin-polyethylene glycol-glutamic acid, cyclodextrin-polyethylene glycol-lysine and cyclodextrin-polyethylene glycol-threonine; The corrosion inhibitor is one or more of crown ether hydroxamic acid, L-glutamic acid γ-monohydroxamic acid and suberoxime; The phosphate compound is alkylphenol polyoxyethylene ether phosphate and / or fatty alcohol polyoxyethylene ether phosphate.

2. The semiconductor cobalt process post-CMP cleaning solution according to claim 1, characterized in that: The organic weak base is one or more of pyridine, imidazole, 1-methylimidazole, butyramide, monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, DL-aminopropanol, 2-(methylamino)ethanol, (S)-(+)-2-amino-1-butanol and N-(2-hydroxyethyl)ethylenediamine.

3. A method for preparing a cleaning solution after CMP in a semiconductor cobalt process according to claim 1 or 2, characterized in that: The following steps are involved: Weigh out the respective amounts of each component; All components are added into a container and mixed until all materials are completely dissolved to prepare a semiconductor cobalt process post-CMP cleaning solution.

4. Use of the semiconductor cobalt process post-CMP cleaning solution according to claim 1 or 2 in the field of cleaning semiconductor chips.

5. The use according to claim 4, characterized in that: A method for cleaning a cobalt wafer using a semiconductor cobalt process post-CMP cleaning solution comprises the following steps: Step 1, diluting the post-CMP cleaning solution with ultrapure water by 10-100 times to obtain a diluted cleaning solution, and using the diluted cleaning solution to soak a cobalt wafer at room temperature to obtain a soaked cobalt wafer; Step 2: Rinse the soaked cobalt wafer in ultrapure water to complete the cleaning of the cobalt wafer.

6. The use according to claim 5, characterized in that: Step 1, the soaking time is 50-200s; And / or, in step 2, the number of flushing times is greater than or equal to three times.

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