Cleaning agent composition for semiconductor material

Abstract

To provide a cleaning agent composition for semiconductor materials with liquid properties near neutral and excellent cleaning performance.SOLUTION: A cleaning agent composition for semiconductor materials contains an anionic surfactant with a critical micelle concentration or higher, a chelating agent, and a pH adjuster, and its pH is 6 to 8.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a cleaning composition for semiconductor materials. More specifically, the present invention relates to a cleaning composition for semiconductor materials having excellent detergency. [Background technology]

[0002] Conventionally, CMP (Chemical-Mechanical-Planarization / Polishing) has been known as a process for planarizing the wafer surface in the semiconductor manufacturing process. In the CMP process, chemical abrasives and polishing pads are used to remove irregularities on the wafer surface and flatten it through a combined action of chemical and mechanical polishing. After polishing, polishing grains and polishing debris remain on the wafer surface. As these residues have a detrimental effect on the electrical properties of semiconductors, cleaning is carried out after the CMP process to remove the residues.

[0003] Cleaning after the CMP step is usually performed by combining chemical cleaning using a cleaning agent with physical cleaning using a brush, etc. Various cleaning agent compositions have been proposed as the above-mentioned cleaning agent (Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2013 / 122172 [Patent Document 2] JP 2020-161511 A [Patent Document 3] JP 2020-191365 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the cleaning power of conventional cleaning compositions used for cleaning semiconductor materials is still insufficient. In particular, when using an abrasive containing fine abrasive particles such as ceria particles, the influence of van der Waals forces and electrostatic interactions on the polished object is large, and the abrasive particles are easily attached, so that conventional cleaning compositions cannot sufficiently remove the abrasive particles, and there are problems such as the residue adhering to the polished object. In addition, the liquid is strongly acidic or strongly alkaline, which may adversely affect the polished object, and care must be taken when handling it.

[0006] In view of the above-mentioned current situation, the present invention has an object to provide a cleaning composition for semiconductor materials which has a nearly neutral liquid pH and is therefore environmentally friendly, highly safe, and has excellent cleaning ability. [Means for solving the problem]

[0007] In order to solve the above problems, the present inventors have conducted extensive research into cleaning compositions for semiconductor materials and have found that a cleaning composition having excellent cleaning ability even at a neutral pH of 6 to 8 can be obtained by containing an anionic surfactant having a critical micelle concentration equal to or higher than the critical micelle concentration, a chelating agent, and a pH adjuster, thereby completing the present invention.

[0008] That is, the present invention provides the following aspects. <1> A cleaning composition for semiconductor materials, comprising an anionic surfactant having a critical micelle concentration of at least 50%, a chelating agent, and a pH adjuster, and having a pH of 6 to 8. <2> The anionic surfactant is a sulfonic acid type or a sulfuric acid type. <1> The cleaning composition for semiconductor materials according to claim 1. <3> The content of the anionic surfactant is equal to or more than the critical micelle concentration and equal to or less than 1 mass % in 100 mass % of the cleaning composition for semiconductor materials. <1> or <2> The cleaning composition for semiconductor materials according to claim 1. <4> The pH adjuster is characterized in that it contains at least one compound selected from the group consisting of organic acids, ammonia, and organic basic compounds. <1> ~ <3> 2. The cleaning agent composition for semiconductor materials according to claim 1 , <5> The cleaning composition for semiconductor materials is for cleaning a substrate containing ceria particles. <1> ~ <4> 2. The cleaning agent composition for semiconductor materials according to claim 1 , <6> The ceria particles have an average particle size of 200 nm or less. <5> The cleaning composition for semiconductor materials according to claim 1. <7> The above-mentioned method is characterized in that it is used in a two-fluid cleaning method. <1> ~ <6> 2. The cleaning agent composition for semiconductor materials according to claim 1 , Effect of the Invention

[0009] The cleaning composition for semiconductor materials of the present invention has excellent cleaning power. In addition, since the liquid has a nearly neutral pH, it is also easy to handle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below. In addition, a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

[0011] <Cleaning composition for semiconductor materials> The cleaning composition for semiconductor materials of the present invention is characterized by comprising an anionic surfactant having a critical micelle concentration equal to or higher than the critical micelle concentration, a chelating agent, and a pH adjuster, and having a pH of 6 to 8. Since the cleaning composition for semiconductor materials of the present invention has the above-mentioned constitution, it has excellent detergency. In addition, since the liquid has a nearly neutral pH, it is easy to handle.

[0012] The reason why the cleaning composition for semiconductor materials of the present invention has excellent cleaning power even when the liquid has a nearly neutral pH is presumably because, after the chelating agent acts on the particles attached to the object to be polished, such as a substrate, the anionic surfactant that forms micelles adheres to and acts around the positively charged abrasive particles, such as ceria particles, to efficiently remove the abrasive particles, and further, by negatively charging the surface potential of the particles, the electrostatic repulsion action with the negatively charged object to be polished prevents redeposition of the abrasive particles on the object to be polished.

[0013] Each component contained in the cleaning composition for semiconductor materials of the present invention will be described.

[0014] (anionic surfactant) The cleaning composition for semiconductor materials of the present invention contains an anionic surfactant at a critical micelle concentration or higher. By containing an anionic surfactant at a critical micelle concentration or higher, the anionic surfactant forms micelles, which adhere to the periphery of abrasive particles such as ceria particles, more efficiently removing the abrasive particles, and preventing redeposition of the abrasive particles on the workpiece to be polished, thereby exhibiting excellent cleaning power.

[0015] In the present invention, the critical micelle concentration of an anionic surfactant is measured by dynamic light scattering (DLS). Specifically, surfactant solutions of various concentrations are prepared, their scattering intensities are measured by dynamic light scattering (DLS), and the concentration (%) and scattering intensity (kpcs) are plotted. The concentration at which the scattering intensity increases rapidly is taken as the critical micelle concentration. Specifically, the critical micelle concentration can be measured by the method described in the Examples below.

[0016] The content of the anionic surfactant is preferably not less than the critical micelle concentration and not more than 1 mass%, more preferably 0.1 to 1 mass%, even more preferably 0.1 to 0.7 mass%, and even more preferably 0.11 to 0.39 mass%, in 100 mass% of the cleaning composition for semiconductor materials, in order to provide better cleaning power.

[0017] The anionic surfactant is not particularly limited, and known surfactants can be used, such as carboxylic acid type anionic surfactants such as aliphatic monocarboxylate, polyoxyethylene alkyl ether carboxylate, N-acyl sarcosine salt, and N-acyl glutamate; sulfosuccinates such as dialkyl sulfosuccinate and dialkylene glycol adduct sulfosuccinate, alkane sulfonate, alpha olefin sulfonate, alkyl benzene sulfonate, naphthalene sulfonate-formaldehyde condensate, alkyl naphthalene sulfonate, and N-methyl-N-acyltaurate; sulfuric acid type anionic surfactants such as alkyl sulfate, polyoxyethylene alkyl ether sulfate, and fat sulfate; and phosphoric acid type anionic surfactants such as alkyl phosphate, polyoxyethylene alkyl ether phosphate, and polyoxyethylene alkyl phenyl ether phosphate. Only one type of anionic surfactant may be used, or two or more types may be used in combination. Among these, in terms of better cleaning power, the anionic surfactant preferably contains a sulfonic acid type or sulfate type anionic surfactant, more preferably contains a sulfonic acid type anionic surfactant, and even more preferably contains a sulfosuccinate.

[0018] The anionic surfactant preferably has 3 to 20 carbon atoms, more preferably 5 to 18 carbon atoms, and even more preferably 6 to 16 carbon atoms.

[0019] (chelating agent) The chelating agent is not particularly limited as long as it is a compound that bonds with metal ions to form a chelate compound, and examples thereof include organic acid compounds and aminopolycarboxylic acid compounds.

[0020] Examples of organic acid compounds include oxalic acid, malonic acid, succinic acid, maleic acid, citric acid, tartaric acid, malic acid, and salts thereof (eg, alkali metal salts, ammonium salts, etc.).

[0021] Examples of the aminopolycarboxylic acid compound include ethylenediaminetetraacetic acid (EDTA) and trans-1,2-diaminocyclohexanetetraacetic acid.

[0022] Among them, the chelating agent is preferably an aminopolycarboxylic acid compound, and more preferably ethylenediaminetetraacetic acid (EDTA), in terms of further improving the cleaning power. The chelating agent may be used alone or in combination of two or more kinds.

[0023] The content of the chelating agent is not particularly limited, but in terms of better cleaning power, it is preferably 0.01 to 2 mass%, more preferably 0.1 to 1 mass%, and even more preferably 0.1 to 0.8 mass%, relative to 100 mass% of the cleaning composition for semiconductor materials.

[0024] (pH adjuster) The pH adjuster is not particularly limited as long as it is a compound capable of adjusting the pH to the desired level, and examples thereof include inorganic acids and their salts, organic acids and their salts, alkali metal hydroxides, ammonia, and organic basic compounds. Only one pH adjuster may be used, or two or more pH adjusters may be used in combination. Among them, the pH adjuster is preferably at least one selected from the group consisting of organic acids, ammonia, and organic basic compounds, more preferably at least one selected from the group consisting of ammonia and organic basic compounds, and even more preferably ammonia, in terms of suppressing the remaining metal after cleaning.

[0025] Examples of the inorganic acid include phosphoric acid, nitric acid, sulfuric acid, and hydrochloric acid.

[0026] Examples of the organic acid include oxycarboxylic acids, polycarboxylic acids, and amino acids.

[0027] Examples of the organic basic compound include alkylamines such as trimethylamine and triethylamine; alkanolamines such as monoethanolamine, diethanolamine, triethanolamine and monoisopropanolamine; and quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, trimethyl-2-hydroxyethylammonium hydroxide (choline), and triethyl(hydroxyethyl)ammonium hydroxide.

[0028] The pH adjuster may partially overlap with the chelating agent described above, but the overlapping compounds may be components that function both as a chelating agent and a pH adjuster.

[0029] The content of the pH adjuster is not particularly limited, and may be appropriately adjusted so that the pH value of the cleaning composition for semiconductor materials of the present invention falls within a predetermined range.

[0030] (solvent) The cleaning composition for semiconductor materials preferably further contains a solvent. Examples of the solvent include water, aprotic polar organic solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide, and dimethylsulfoxide, and protic organic solvents such as lower alcohols, aromatic alcohols, and glycols. Of these, the solvent preferably contains water. The solvent may be a mixture containing two or more kinds of solvents.

[0031] (Other Ingredients) The cleaning composition for semiconductor materials may further contain other components in addition to the above-mentioned components. Examples of other components include cationic surfactants, nonionic surfactants, corrosion inhibitors, solubilizers, preservatives, antibacterial agents, antioxidants, etc. These can be appropriately selected from known components that are usually used in cleaning compositions for semiconductor materials. The content of the other components is not particularly limited as long as it does not adversely affect the effects of the present invention, but is preferably 0 to 10 mass%, more preferably 0 to 7 mass%, and even more preferably 0 to 5 mass%.

[0032] (pH) The pH (hydrogen ion concentration) of the cleaning composition for semiconductor materials is 6 to 8. The pH of the cleaning composition for semiconductor materials can be adjusted by adjusting the content of the pH adjuster described above. The pH is the pH of the cleaning composition for semiconductor materials at 25° C. when it is used, and can be determined using a pH meter (e.g., F71S, manufactured by Horiba, Ltd.).

[0033] <Preparation of cleaning composition for semiconductor materials> The cleaning composition for semiconductor materials can be prepared by mixing the above-mentioned anionic surfactant, chelating agent, pH adjuster, and other components as necessary such as a solvent, etc. The mixing can be carried out by any mixing / dispersing means such as a known stirrer, mixer, disperser, etc. without any particular limitation.

[0034] The cleaning composition for semiconductor materials may be prepared as a concentrate. When using the cleaning composition for semiconductor materials, the concentrate is appropriately diluted. The content of each component and pH in this specification are values ​​at the time of using the cleaning composition for semiconductor materials and during cleaning.

[0035] <How to use> The cleaning composition for semiconductor materials of the present invention is preferably used for cleaning semiconductor materials. In particular, it is preferably used in the cleaning step of semiconductor materials after the CMP step in the semiconductor manufacturing process. By using the cleaning composition for semiconductor materials of the present invention in the cleaning step after the CMP step, abrasive particles and polishing debris can be sufficiently removed. Also, redeposition of these residues can be prevented.

[0036] Examples of the CMP process include known methods in which an abrasive composition is dropped onto an object to be polished, and the object is polished by rotating the object while being in contact with a polishing pad or the like.

[0037] The object to be polished includes a semiconductor material, preferably a semiconductor substrate, and is not particularly limited, and examples of the semiconductor substrate include known semiconductor substrates made of silicon, silicon carbide, silicon nitride, gallium arsenide, gallium nitride, gallium phosphide, indium phosphide, etc.

[0038] The semiconductor substrate may be provided with metal wiring, and examples of the metal wiring include copper wiring, tungsten wiring, aluminum wiring, cobalt wiring, and alloy wiring of these metals with other metals, etc. Examples of the other metals include metals such as tungsten, titanium, tantalum, and chromium.

[0039] The semiconductor substrate may be anticorrosive. Examples of the anticorrosive treatment include a method of applying an anticorrosive agent to the surface of the semiconductor substrate and drying or heating the surface to form a coating (protective film). The anticorrosive agent is not particularly limited, and examples of the anticorrosive agent include compounds known as anticorrosive agents, such as benzotriazoles, imidazoles, quinaldines, and quinolines.

[0040] The semiconductor substrate may include an insulating film. Examples of the insulating film include a p-TEOS thermal oxide film, silicon nitride (SiN), silicon carbide nitride (SiCN), a low dielectric constant film Low-k (SiOC, SiC), cobalt silicide (CoSi 2) and the like. In addition, it may contain a barrier metal (Ta, TaN, TiN, etc.).

[0041] After the CMP process, polishing debris and organic residues from the metal wiring, protective film, insulating film, etc. described above remain on the surface of the semiconductor substrate, as well as the abrasive used in the CMP process.

[0042] The above-mentioned abrasive is a slurry of abrasive particles. Examples of the above-mentioned abrasive particles include inorganic particles such as metal oxide particles such as silica, alumina, ceria, titania, and zirconia, and organic particles such as polymethylmethacrylate (PMMA) particles. Among them, inorganic particles are preferred, and ceria is more preferred. Only one type of abrasive particles may be used, or two or more types may be used.

[0043] The average particle size of the abrasive particles is preferably 200 nm or less, more preferably 10 to 200 nm. The average particle size is a value obtained by measuring by dynamic light scattering. By using such fine abrasive particles, the surface of the semiconductor substrate can be well planarized, while the abrasive particles tend to adhere to the substrate surface after polishing, aggregate, and remain. The cleaning composition for semiconductor materials of the present invention can well remove fine abrasive particles adhered to the substrate surface. The cleaning composition for semiconductor materials is preferably for cleaning substrates containing ceria particles. In addition, the ceria particles preferably have an average particle size of 200 nm or less.

[0044] The method for cleaning the substrate surface after the CMP process using the cleaning composition for semiconductor materials of the present invention is not particularly limited and may be performed by a known method, for example, a method of cleaning the substrate surface after the CMP process by immersing it in the cleaning composition for semiconductor materials, a spin-type or spray-type cleaning method, etc. may be mentioned. In addition, it may be a batch type in which a plurality of substrates are treated at once, or a single-wafer type in which substrates are treated one by one. Among them, the cleaning composition for semiconductor materials is preferably used in a two-fluid cleaning method.

[0045] The two-fluid cleaning is a method of cleaning a substrate surface by spraying a cleaning composition and a gas while mixing them, and can be carried out using a known two-fluid cleaning device.

[0046] In the method for cleaning a substrate surface with the above-mentioned cleaning composition for semiconductor materials, the cleaning time is not particularly limited and may be appropriately adjusted depending on the substrate to be cleaned. From the viewpoint of efficiency, however, it is preferably 10 to 300 seconds, more preferably 10 to 100 seconds.

[0047] The temperature of the cleaning composition for semiconductor materials during cleaning is not particularly limited, but is preferably from 20 to 40°C, and more preferably from 20 to 35°C, for example.

[0048] As described above, the cleaning composition for semiconductor materials of the present invention has excellent cleaning power and can effectively remove abrasive particles such as fine ceria particles and polishing debris adhering to the surface of a semiconductor substrate. EXAMPLES

[0049] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In addition, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0050] The evaluation methods used in the examples are as follows. <Measurement of the critical micelle concentration (CMC) of surfactants> The surfactant critical micelle concentration (CMC) was adjusted in increments of 0.04% in the range of 0.01 to 0.45%, and the scattering intensity of each solution was measured by dynamic light scattering (DLS) using a Malvern Nano ZS (Malvern Panalytical). The concentration (%) and scattering intensity (kpcs) were plotted, and the concentration at which the scattering intensity increased rapidly was taken as the critical micelle concentration (CMC). The CMCs of the surfactants used are shown in Table 1.

[0051] [Table 1]

[0052] <Cleaning performance evaluation> 1) Preparation of cleaning performance evaluation substrate (Preparation Example 1) Preparation of positively charged ceria nanoparticle dispersion (A1) Colloidal ceria (product name HC30, manufactured by Solvay) with an average particle size of 30 nm was dispersed in ultrapure water at a concentration of 0.05% by mass, while proline (manufactured by Sigma-Aldrich) was added to a concentration of 0.025% by mass and stirred. Finally, the pH was adjusted to 4.0 with nitric acid to obtain a positively charged ceria nanoparticle dispersion (A1).

[0053] 2) SiO for cleaning performance evaluation 2 Substrate preparation An 8-inch silicon wafer was prepared, and the above-mentioned positively charged ceria nanoparticle dispersion (A1) was dropped onto it for 1 minute while stirring with a spin coater to create a contaminated wafer. The contaminated wafer was dried at room temperature to prepare a substrate for evaluating cleaning performance. The surface condition of the evaluation substrate was observed at 30,000x magnification using a scanning electron microscope (FE-SEM, manufacturer: JEOL, model number: JSM7900F-LV).

[0054] 3) Cleaning test The evaluation substrate was placed on a cleaning table and rotated at 100 rpm. The cleaning composition was sprayed from a 1 mm diameter nozzle at a flow rate of 180 ml / min and a pressure of 1250 pSi for 1 minute at 25° C. using a two-fluid cleaning device (a device combining air and a liquid jet passing through an atomizing spray nozzle). The distance from the nozzle of the two-fluid cleaning device to the evaluation substrate was 5 cm. The surface condition of the evaluation substrate after cleaning was observed at 30,000x magnification using a scanning electron microscope (FE-SEM, manufacturer: JEOL, model number: JSM7900F-LV). The approximate number of particles on the evaluation substrate before and after cleaning was calculated using ImageJ software (a Java (registered trademark)-based image processing program), and the cleaning rate was calculated using the following formula. Cleaning rate (%) = (number of contaminating particles before cleaning - number of contaminating particles after cleaning) / number of contaminating particles before cleaning x 100 This was repeated at three arbitrary locations on the evaluation substrate, and the average cleaning efficiency was calculated.

[0055] (Examples 1 to 3, Comparative Examples 1 to 3) Water, a chelating agent, and a surfactant were mixed according to the formulation shown in Table 2, and ammonia water was added to adjust the pH to a predetermined level, thereby preparing a cleaning composition.

[0056] The surfactants used in the examples and comparative examples are shown below. (SFT-MES-A, SFT-MES-B) (anionic surfactants)

[0057] [ka] SFT-MES-A: n=3 SFT-MES-B: n=5

[0058] [ka]

[0059] The cleaning performance of the cleaning compositions obtained in the above Examples and Comparative Examples was evaluated by the above-mentioned method. The results are shown in Table 2.

[0060] [Table 2]

[0061] From Table 2, it was found that the cleaning composition of the example, which contained an anionic surfactant at a concentration equal to or higher than the CMC, a chelating agent, and a pH adjuster and had a pH of 7, had excellent cleaning power.

Claims

1. The composition comprises an anionic surfactant having a critical micelle concentration equal to or higher than the critical micelle concentration, a chelating agent, and a pH adjuster, pH is 6-8 A cleaning composition for semiconductor materials, comprising:

2. 2. The cleaning composition for semiconductor materials according to claim 1, wherein the anionic surfactant is a sulfonic acid type or a sulfuric acid type.

3. 2. The cleaning composition for semiconductor materials according to claim 1, wherein the content of the anionic surfactant is equal to or higher than a critical micelle concentration and equal to or lower than 1 mass % based on 100 mass % of the cleaning composition for semiconductor materials.

4. 2. The cleaning composition for semiconductor materials according to claim 1, wherein the pH adjuster comprises at least one compound selected from the group consisting of an organic acid, ammonia, and an organic basic compound.

5. The cleaning composition for semiconductor materials according to claim 1, which is for cleaning a substrate containing ceria particles.

6. 6. The cleaning composition for semiconductor materials according to claim 5, wherein the ceria particles have an average particle size of 200 nm or less.

7. 2. The cleaning composition for semiconductor materials according to claim 1, which is used in a two-fluid cleaning method.

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