A long-life chip cleaning solution for stable etching of TiN, its preparation method and application

Abstract

The present invention provides a long-life chip cleaning solution for stably etching TiN, a preparation method thereof, and an application. The long-life chip cleaning solution for stably etching TiN according to the present invention comprises the following components in parts by weight: 0.3-1 part of a cyclic compound; 15-25 parts of hydrogen peroxide; 5-15 parts of an alkali; 0.1-0.5 part of a corrosion inhibitor; and 50-90 parts of ultrapure water. The long-life chip cleaning solution for stably etching TiN according to the present invention can effectively inhibit the decomposition of hydrogen peroxide and stably etch a titanium nitride hard mask. When continuously feeding chips, the long-life chip cleaning solution for stably etching TiN according to the present invention can still stably etch the titanium nitride hard mask, and at the same time ensure that the residues on the chips are completely cleaned. The long-life chip cleaning solution for stably etching TiN according to the present invention has very good application prospects and great potential for large-scale industrial promotion in the field of semiconductor chip cleaning.

Description

Technical Field

[0001] The present invention relates to the technology of chip cleaning fluids, and particularly to a long-life chip cleaning fluid for stably etching TiN, a preparation method thereof, and an application thereof. Background Art

[0002] Thanks to the development of the damascene process, the application of copper metal interconnects in integrated circuits (ICs) has been promoted. Usually, plasma dry etching is applied in the copper (Cu) / low-k dual damascene manufacturing process. During the etching process, polymers and particle residues generated on the sidewalls and at the bottom must be removed before the next process step. As the technology node develops towards 45 nm and smaller, the reduction in the size of semiconductor devices makes it more difficult to achieve critical profile control of vias and trenches. IC device companies are researching the use of various hard masks to improve the etching selectivity for low-k materials, thereby obtaining better profile control.

[0003] Currently, titanium nitride (TiN) has become the main application material for metal hard masks. However, too thick TiN will cause undercutting of the hard mask and also cause difficulties in subsequent chemical mechanical polishing (CMP). Therefore, partial removal / total removal of TiN will save resources and simplify the process flow to a great extent.

[0004] In the cleaning process, the cleaning fluid needs to maintain a stable etching rate for a long time, and increasing the etching rate of TiN can ensure the improvement of the production efficiency of the production line. Hydrogen peroxide can be used as an etchant for TiN, but in the presence of copper ions, hydrogen peroxide will decompose rapidly, shortening the life of the cleaning fluid. In addition, as TiN is continuously etched, a large amount of titanyl ions will accumulate in the cleaning fluid, and when the concentration of titanyl ions reaches a saturated state, the etching rate of TiN will decrease. The above two defects are problems that need to be solved urgently for existing TiN cleaning fluids. Summary of the Invention

[0005] The object of the present invention is to propose a long-life chip cleaning fluid for stably etching TiN in view of the problems of short life and unstable etching rate existing in the existing hydrogen peroxide chip cleaning fluid. This cleaning fluid can effectively inhibit the decomposition of hydrogen peroxide and stably etch the titanium nitride hard mask. When continuously feeding chips, this cleaning fluid can still stably etch the titanium nitride hard mask while ensuring that the residues on the chips are completely cleaned.

[0006] It should be noted that in the present invention, unless otherwise specified, the specific meaning of "including" involving composition limitation and description includes both the open "including", "comprising" and their similar meanings, and also the closed "consisting of", "constituted by" and their similar meanings.

[0007] To achieve the above object, the technical solution adopted by the present invention is: A long-life chip cleaning solution for stably etching TiN, comprising the following components in weight ratio:

[0008]

[0009] Further, the cyclic compound is one or more of phthalocyanine tetrasulfonic acid, 5,28-dihydro-29H,31H-phthalocyanine, diaza-18-crown-6, and 1-aza-18-crown-6-ether.

[0010] Further, the cyclic compound is preferably phthalocyanine tetrasulfonic acid.

[0011] Further, the amount of the cyclic compound is 0.3 - 0.6 parts.

[0012] TiN reacts with perhydroxide ions to form tetravalent titanium ions, and Ti 4+ exists in the form of titanyl ions (TiO 2+ ) in aqueous solution. With the continuous etching of TiN, the titanyl ions (TiO 2+ ) in the cleaning solution accumulate continuously. When the concentration of titanyl ions (TiO 2 + ) is about to reach the saturation state, the forward reaction of this reaction is very difficult to proceed, which leads to a decrease in the etching rate. The reaction principle is as follows.

[0013]

[0014] The cyclic compound adopted by the present invention can self-assemble with titanyl ions to form a stable complex like a spider web. The consumption of titanyl ions promotes the forward reaction of TiN with perhydroxide ions, thereby ensuring a stable etching rate of TiN.

[0015] When the cyclic compound is phthalocyanine tetrasulfonic acid, it not only contains sulfonic acid groups and hydroxyl groups that can coordinate with metal ions, which helps to inhibit the self-decomposition of hydrogen peroxide under the catalytic action of metal ions, but also phthalocyanine is a completely symmetric macrocyclic compound that can stably chelate titanyl ions in the middle to form a stable titanium compound, promoting the forward reaction process of TiN with perhydroxide ions, thus increasing the etching rate. At the same time, the hydroxyl groups and sulfonic acid groups have certain hydrophilicity, which can dissolve the formed titanium compound in water and is easy to rinse.

[0016] Further, the amount of hydrogen peroxide is 15 - 20 parts.

[0017] Further, the mass ratio of the cyclic compound to hydrogen peroxide is 1:15 - 55.

[0018] Further, the mass ratio of the cyclic compound to hydrogen peroxide is preferably 1:36.

[0019] Further, the base is one or more of isobutanolamine, diethanolamine, monoethanolamine, diethylene glycol amine, isopropanolamine, and N-methylethanolamine.

[0020] Further, the base is preferably diethanolamine and / or isobutanolamine.

[0021] Further, the base is most preferably isobutanolamine.

[0022] Further, the amount of the base is 10 - 15 parts.

[0023] Further, the corrosion inhibitor is one or more of 4,5,6,7-tetrafluoro-1H-indazole, 5-(trifluoromethyl)-1H-indazole, 4,6-difluoro-1H-indazole, and 4-fluoro-1H-indazole.

[0024] Further, the corrosion inhibitor is preferably 4,5,6,7-tetrafluoro-1H-indazole.

[0025] Further, the amount of the corrosion inhibitor is 0.2 - 0.4 parts.

[0026] Further, the amount of the ultrapure water is 60 - 75 parts.

[0027] Another object of the present invention also discloses a method for preparing a long-life chip cleaning solution for stably etching TiN, comprising the following steps:

[0028] Mix and stir the components until all components are completely dissolved, thus obtaining the cleaning solution with a stable etching rate and a long life.

[0029] Another object of the present invention also discloses an application of a long-life chip cleaning solution for stably etching TiN in the field of chip cleaning.

[0030] Further, cleaning the chip with the long-life chip cleaning solution for stably etching TiN comprises the following steps:

[0031] Step 1: Immerse the chip in the heated long-life chip cleaning solution for stably etching TiN to obtain the cleaned chip;

[0032] Step 2: Rinse the cleaned chip with ultrapure water, thus completing the chip cleaning process.

[0033] Further, the heating temperature is 30 - 50°C.

[0034] Further, the immersion time is 5 - 30 min.

[0035] Further, the ultrapure water is deionized water with a resistance of at least 18 MΩ.

[0036] Furthermore, the ultra-pure water rinsing time is 1 - 5 min.

[0037] The long-life chip cleaning solution for stably etching TiN, its preparation method and application of the present invention have the following advantages compared with the prior art:

[0038] 1), When TiN reacts with peroxide ions, tetravalent titanium ions will be generated. Ti 4+ exists in the aqueous solution in the form of titanyl ions (TiO 2+ ). With the continuous etching of TiN, the titanyl ions in the cleaning solution accumulate continuously. When the concentration of titanyl ions is about to reach the saturation state, this reaction is difficult to proceed forward, which leads to a decrease in the etching rate. The cyclic compounds adopted in the present invention can self-assemble with titanyl ions to form stable complexes like a spider web. The consumption of titanyl ions promotes the forward reaction of TiN with peroxide ions, thereby ensuring a stable etching rate of TiN. Especially when the cyclic compound is phthalocyanine tetrasulfonic acid, not only does it contain sulfonic acid groups and hydroxyl groups that can coordinate with metal ions, which helps to inhibit the self-decomposition of hydrogen peroxide under the catalytic action of metal ions, but phthalocyanine is also a completely symmetric macrocyclic compound that can stably chelate titanyl ions in the middle to form stable titanium compounds, promoting the forward reaction process of TiN with peroxide ions, thus increasing the etching rate. At the same time, the hydroxyl groups and sulfonic acid groups have certain hydrophilicity, which can dissolve the formed titanium compounds in water and are easy to rinse.

[0039] 2), The long-life chip cleaning solution for stably etching TiN of the present invention uses a fluorinated indazole compound as a corrosion inhibitor, which can stably supply fluorine sources to remove cleaning residues and can also chelate metal ions.

[0040] 3), The long-life chip cleaning solution for stably etching TiN of the present invention has no special requirements for the chip corrosion-free cleaning process and does not require ultrasonic treatment. Only under the immersion process, the contaminants and various particles adhered to the chip can be completely eluted, and only subsequent pure water rinsing is required, and there is no dirt residue after water washing.

[0041] In summary, the long-life chip cleaning solution for stably etching TiN of the present invention has very good application prospects and the potential for large-scale industrial promotion in the field of semiconductor chip cleaning. Description of the Drawings

[0042] Figure 1 It is the SEM effect diagram of the chip with a large amount of residues before cleaning; the magnification is 200,000 times.

[0043] Figure 2 It is the cleaning SEM effect diagram after the long-life chip cleaning solution provided in Example 1 is continuously put into 60 chips; the magnification is 200,000 times. Detailed implementation manners

[0044] The present invention will be further described below in conjunction with embodiments. The descriptions of the technical features recorded below are based on representative implementation manners and specific examples of the present invention, but the present invention is not limited to these implementation manners and specific examples. It should be noted that:

[0045] 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 systematic errors that are inevitable in industrial production.

[0046] In this specification, the numerical range expressed by "numerical value A to numerical value B" refers to the range including the endpoint numerical values A and B.

[0047] In this specification, the numerical range expressed by "above" or "below" refers to the numerical range including this number.

[0048] In this specification, the meaning expressed by "can" includes the meanings of both performing a certain process and not performing a certain process.

[0049] In this specification, "optional" or "optional" means that certain substances, components, execution steps, applied conditions and other factors are used or not used.

[0050] In this specification, when "normal temperature" or "room temperature" is used, the temperature can be 15 - 25 °C.

[0051] In this specification, for the reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchase.

[0052] Examples 1 - 6

[0053] Examples 1 - 6 provide a variety of long - life chip cleaning fluids for stably etching TiN, and the components and weight ratios thereof are shown in Table 1. The preparation method thereof includes the following steps:

[0054] Step 1: Weigh each component in their respective amounts;

[0055] Step 2: Add the above - mentioned materials into a container and stir until all the materials are completely dissolved, thus obtaining the cleaning fluid with stable etching rate and long life.

[0056] Table 1 Components and weight ratios included in Examples 1 - 6

[0057]

[0058]

[0059] Comparative Examples 1 - 3

[0060] Comparative Examples 1-3 provided a variety of chip cleaning fluids, and the components and weight ratios thereof are shown in Table 2. The preparation method is the same as that of Example 1.

[0061] Table 2 Components and weight ratios included in Comparative Examples 1-3

[0062]

[0063] Next, various performances of the above-mentioned examples or comparative examples were tested, and the specific test results are shown in Table 3:

[0064] Table 3 Test data

[0065]

[0066]

[0067] It can be seen from Table 3 that compared with the etching rate of the initial TiN, the etching speed of the long-life chip cleaning fluids for stably etching TiN in Examples 1-6 decreased relatively slowly or hardly decreased. Since hydrogen peroxide is easily decomposed by heat during continuous heating, for the same heating time, less hydrogen peroxide in the long-life chip cleaning fluids for stably etching TiN in Examples 1-6 decomposed, and the long-life chip cleaning fluids for stably etching TiN in Examples 1-6 had a long service life. However, in Comparative Example 1, due to the absence of tetra-sulfonated phthalocyanine, a large amount of hydrogen peroxide decomposed, shortening the service life of the cleaning fluid, and in the case of continuously feeding chips, the TiN etching rate was only In Comparative Example 2, β-cyclodextrin was used as the cyclic compound. Although the cleaning effect could be ensured, it could not inhibit the decomposition of hydrogen peroxide. In the case of continuously feeding chips, the etching rate was only In Comparative Example 3, due to the absence of a fluoride-containing corrosion inhibitor, the polymer could not be peeled off from the sidewalls or the bottom, and the cleaning effect could not be achieved. In the case of continuously feeding chips, the etching rate of TiN also decreased to a certain extent.

[0068] Figure 1 SEM effect diagram of a chip with a large amount of residues before cleaning; the magnification is 200,000 times. Figure 2 SEM effect diagram of cleaning after continuously feeding 60 chips with the long-life chip cleaning fluid provided in Example 1; the magnification is 200,000 times. From Figure 1 and Figure 2 it can be seen that the surface of the chip cleaned with the long-life chip cleaning fluid prepared in Example 1 of the present invention had no residue, and had a good cleaning effect.

[0069] Among them:

[0070] The test method for Performance 1 cleaning effect is as follows:

[0071] After dry etching, a large amount of residues remained on the sidewalls and bottom of the trenches of the chip with silicon as the substrate. The cleaning liquid of the above-mentioned embodiments and comparative examples of the present invention was used to clean the chip. The cleaning treatment method includes the following steps:

[0072] Step 1: Take 30 mL of the prepared cleaning liquid, heat it to 30 °C in a water bath, put one chip into the cleaning liquid heated in the water bath, after soaking for 10 min, add a new chip; repeat the above operation until 60 chips are continuously put in;

[0073] Step 2: Rinse the cleaned chip with ultrapure water for 2 min, then the cleaning process of the chip is completed. Observe the cleaning effect after continuously putting in 60 chips by SEM. The test results are shown in Figures 1-2 and Table 3.

[0074] The test method for Performance 2 titanium nitride etching rate is as follows:

[0075] The four-point probe method is used to test the etching rate of titanium nitride with different cleaning liquids. The specific test method is as follows: Put a 2×2 cm 2 titanium nitride sheet into the cleaning liquid at 30 °C, after soaking for 10 min, put it into ultrapure water and rinse twice and dry. Then use the four-probe method to measure the thickness of titanium nitride before and after soaking, and calculate the etching rate of the initial titanium nitride;

[0076] After an interval of 12 hours, put a 2×2 cm 2 titanium nitride sheet into the above-mentioned cleaning liquid again, repeat the above operation, and calculate the etching rate after putting in 60 2×2 cm 2 titanium nitride sheets. The test results are shown in Table 3.

[0077] The ultrapure water used in the above steps is deionized water with a resistance of at least 18 MΩ.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some 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 invention.

Claims

1. A long-life chip cleaning solution for stable etching of TiN, characterized in that, It consists of the following components by weight ratio: Cyclic compound: 0.3 - 1 part; Hydrogen peroxide: 15 - 25 parts; Base: 5 - 15 parts; Corrosion inhibitor: 0.1 - 0.5 part; Ultra-pure water: 50 - 90 parts; The cyclic compound is one or more of tetrasulfonic acid phthalocyanine, 5,28-dihydro-29H,31H-phthalocyanine, diaza-18-crown-6, and 1-aza-18-crown-6-ether; The corrosion inhibitor is a fluorinated indazole compound.

2. The long-life chip cleaning solution for stably etching TiN according to claim 1, wherein, The mass ratio of the cyclic compound to hydrogen peroxide is 1:15 - 55.

3. The long-life chip cleaning solution for stably etching TiN according to claim 1, wherein The base is one or more of isobutanolamine, diethanolamine, monoethanolamine, diethylene glycolamine, isopropanolamine, and N-methylethanolamine.

4. The long-life chip cleaning solution for stably etching TiN according to claim 1, wherein, The corrosion inhibitor is one or more of 4,5,6,7-tetrafluoro-1H-indazole, 5-trifluoromethyl-1H-indazole, 4,6-difluoro-1H-indazole, and 4-fluoro-1H-indazole.

5. A method for preparing a long-life chip cleaning solution for stable etching of TiN according to any one of claims 1-4, characterized in that, It includes the following steps: Mix and stir the components until all components are completely dissolved to obtain the long-life chip cleaning solution for stably etching TiN.

6. Application of the long-life chip cleaning solution for stably etching TiN according to any one of claims 1 - 4 in the field of chip cleaning.

7. The application according to claim 6, wherein When using the long-life chip cleaning solution for stably etching TiN to clean the chip, it includes the following steps: Step 1: Immerse the chip in the heated long-life chip cleaning solution for stably etching TiN to obtain the cleaned chip; Step 2: Rinse the cleaned chip with ultra-pure water to complete the chip cleaning process.

8. The application according to claim 7, wherein The heating temperature is 30 - 50 °C; and / or, the immersion time is 5 - 30 min.

9. The application according to claim 7, characterized in that The rinsing time with ultra-pure water is 1 - 5 min.

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