Post-CMP cleaning composition and post-CMP cleaning method

Abstract

A post-CMP cleaning composition and a post-CMP cleaning method are provided that can more effectively reduce impurities remaining on the surface of a polished object. [Solution] A post-CMP cleaning composition used to clean a polished object that has been subjected to chemical mechanical polishing (CMP), contains water, a water-soluble polymer, and a surfactant; when the surface of the polished object is covered with the post-CMP cleaning composition, when observed with an atomic force microscope, the restoring adhesion force, which is the force acting between the surfactant and a probe of the atomic force microscope having a tip curvature radius of 2 nm or more and 12 nm or less, is greater than 0 N / m and not greater than 0.07 N / m; and the surface roughness of the adsorption layer formed by adsorption of the surfactant on the surface of the polished object is greater than 0 nm and not greater than 0.4 nm.

Description

[Technical Field]

[0001] The present invention relates to a post-CMP cleaning composition and a post-CMP cleaning method. [Background technology]

[0002] In recent years, with the trend toward multilayer wiring on semiconductor substrate surfaces, so-called chemical mechanical polishing (CMP) technology has been used to polish and planarize semiconductor substrates when manufacturing devices. CMP is a method of planarizing the surface of an object to be polished (workpiece) such as a semiconductor substrate using a polishing composition (slurry) containing abrasive grains such as silica, alumina, or ceria, an anticorrosive, a surfactant, etc. The object to be polished (workpiece) can be a wiring, plug, or the like made of silicon, polysilicon, silicon oxide film (silicon oxide), silicon nitride, or metal.

[0003] After the CMP process, a large amount of impurities, such as foreign matter and residues, remain on the surface of a semiconductor substrate. These impurities include organic substances such as abrasive grains, metals, anticorrosives, and surfactants derived from the polishing composition used in CMP, silicon-containing materials derived from the object to be polished, silicon-containing materials and metals generated by polishing wiring, plugs, etc., and organic substances such as pad debris generated from various pads used in polishing.

[0004] If the semiconductor substrate surface is contaminated with such impurities, the electrical characteristics of the semiconductor may deteriorate, potentially reducing the reliability of devices using the semiconductor. Therefore, it is desirable to introduce a cleaning step after the CMP step to remove these impurities from the semiconductor substrate surface. Post-CMP cleaning compositions used for cleaning after such a CMP step, i.e., post-CMP cleaning, contain a water-soluble polymer to control the cleaning function (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-155133 [Patent Document 2] Japanese Patent Application Publication No. 2022-155989 Summary of the Invention [Problem to be solved by the invention]

[0006] However, at the most advanced semiconductor process nodes, the surface of semiconductor substrates is becoming increasingly miniaturized, and the impact of impurities remaining on the semiconductor substrates is becoming even greater. Therefore, there is a need for a cleaning composition and a cleaning method that can more effectively reduce impurities remaining on the semiconductor substrate surface after CMP polishing.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a post-CMP cleaning composition and a post-CMP cleaning method that can more effectively reduce impurities remaining on the surface of a polished object. [Means for solving the problem]

[0008] A post-CMP cleaning composition according to one embodiment of the present invention is a post-CMP cleaning composition used for cleaning a polished object that has been subjected to chemical mechanical polishing (CMP), the post-CMP cleaning composition containing water, a water-soluble polymer, and a surfactant, wherein when the surface of the polished object is covered with the post-CMP cleaning composition and observed using an atomic force microscope, the restoring adhesion force acting between the surfactant and a probe of the atomic force microscope having a tip curvature radius of 2 nm to 12 nm is greater than 0 N / m and not greater than 0.07 N / m, and the surface roughness of an adsorption layer formed by adsorption of the surfactant on the surface of the polished object is greater than 0 nm and not greater than 0.4 nm.

[0009] In addition, a post-CMP cleaning method according to another embodiment of the present invention is a method for post-CMP cleaning of a polished object having a layer containing a silicon-containing material, using the post-CMP cleaning composition according to the present invention. The post-CMP cleaning method includes contacting a surface of the polished object with the post-CMP cleaning composition to form a surface treatment layer containing the water, the water-soluble polymer, and the surfactant on the surface of the polished object having the layer containing the silicon-containing material. The surface treatment layer has an adsorption layer formed by adsorption of the surfactant on the surface of the polished object having the layer containing the silicon-containing material. When observed with the atomic force microscope, the restoring adhesion force acting between a probe of the atomic force microscope having a tip curvature radius of 2 nm to 12 nm and the surfactant in the surface treatment layer is greater than 0 N / m and less than 0.07 N / m, and the surface roughness of the adsorption layer is greater than 0 nm and less than 0.4 nm. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a post-CMP cleaning composition and a post-CMP cleaning method that can more effectively reduce impurities remaining on the surface of a polished object. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will be described in detail. Note that the following embodiment shows an example of the present invention, and the present invention is not limited to the embodiment. Furthermore, various modifications and improvements can be made to the following embodiment, and such modifications and improvements can also be included in the present invention.

[0012] (Post-CMP cleaning composition) One embodiment of the present invention is a post-CMP cleaning composition used for cleaning a polished object that has been subjected to chemical mechanical polishing (CMP), the post-CMP cleaning composition containing water, a water-soluble polymer, and a surfactant. Furthermore, when the surface of the polished object is covered with the post-CMP cleaning composition of this embodiment and observed with an atomic force microscope, the restoring adhesion force, which is the force acting between the surfactant and a probe tip of the atomic force microscope having a tip curvature radius of 2 nm to 12 nm, is greater than 0 N / m and less than 0.07 N / m, and the surface roughness of the adsorption layer formed by adsorption of the surfactant on the surface of the polished object is greater than 0 nm and less than 0.4 nm.

[0013] The present inventors have found that the use of a post-CMP cleaning composition having the above-described configuration prevents residues detached from the polished surface of an object to be polished from reattaching to the surface of the object to be polished and also facilitates the residues to be detached from the surfactant in the post-CMP cleaning composition. Therefore, the use of the post-CMP cleaning composition according to this embodiment makes it possible to effectively remove residues remaining on the surface of an object to be polished.

[0014] (Polished object) In this specification, the term "polished object" refers to an object that has been polished in a polishing process, which is a chemical mechanical polishing (CMP) process. The polished object according to this embodiment may have a layer containing a silicon-containing material. Examples of silicon-containing materials include elemental silicon, polycrystalline silicon, and silicon compounds. Examples of elemental silicon include single-crystal silicon, polycrystalline silicon (polysilicon), and amorphous silicon. Examples of silicon compounds include silicon nitride (SiN), silicon oxide (SiO), silicon carbide (SiC), and silicon germanium (SiGe). Silicon-containing materials also include low-dielectric-constant materials with a relative dielectric constant of 3 or less. Furthermore, n-type impurity-doped polysilicon and p-type impurity-doped polysilicon are also included in the polished object according to this embodiment. These silicon-containing materials may be used alone or in combination of two or more.

[0015] The layer containing a silicon-containing material may contain other materials in addition to the silicon-containing material. Examples of other materials include carbon and metals. Examples of metals include tungsten (W), copper (Cu), aluminum (Al), hafnium (Hf), cobalt (Co), nickel (Ni), titanium (Ti), tantalum (Ta), gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), and osmium (Os). These metals may be used alone or in combination of two or more.

[0016] (residue) In this specification, residue refers to foreign matter adhering to the surface of the polished object. Examples of residue are not particularly limited, but include, for example, organic residues as described below, particle residues derived from abrasive grains contained in the polishing composition, residues consisting of components other than particle residues and organic residues, and mixtures of particle residues and organic residues. In addition, organic residue refers to components consisting of organic substances such as organic low molecular weight compounds and polymer compounds, and organic salts, among the foreign matter adhering to the surface of the polished object.

[0017] In this specification, the total number of residues means the total number of all residues regardless of type. The total number of residues can be measured using a wafer defect inspection device. Details of the method for measuring the number of residues will be described in the Examples below. Examples of organic residues adhering to the polished object include pad dust generated from the pad used in the polishing step or rinse polishing step described below, and various components derived from the polishing composition used in the polishing step or the rinse polishing composition used in the rinse polishing step.

[0018] Since organic residues and other foreign matter differ greatly in color and shape, whether or not a foreign matter is organic residue can be determined by visual observation using a scanning electron microscope (SEM) or by elemental analysis using an energy dispersive X-ray analyzer (EDX) attached to the scanning electron microscope. The number of organic residues can also be measured using a scanning electron microscope or energy dispersive X-ray analyzer, in addition to a wafer defect inspection device.

[0019] (Recovery adhesive force and surface roughness) In the post-CMP cleaning composition according to this embodiment, when the surface of a polished object is covered with the post-CMP cleaning composition, the restoring adhesive force acting between a probe having a tip curvature radius of 2 nm or more and 12 nm or less and a surfactant is greater than 0 N / m and less than 0.07 N / m, and the surface roughness of the surface of the polished object covered with the post-CMP cleaning composition is greater than 0 nm and less than 0.4 nm, as measured with an atomic force microscope (AFM).

[0020] When the post-CMP cleaning composition comes into contact with the surface of the polished object, the surface of the polished object is covered with the post-CMP cleaning composition. At this time, if the surface of the polished object is hydrophilic, the surfactant contained in the post-CMP cleaning composition forms aggregates such as micelles with the hydrophilic groups facing the surface of the polished object. Furthermore, if the surface of the polished object is hydrophobic, the surfactant contained in the post-CMP cleaning composition forms aggregates such as micelles with the hydrophobic groups facing the surface of the polished object. Therefore, an adsorption layer is formed on the surface of the polished object by the surfactant aggregates. The surface of the formed adsorption layer has an uneven shape that conforms to the shape of the surfactant aggregates.

[0021] Repulsive forces such as zeta potential are generated between the adsorption layer formed on the surface of the polished object and the residues approaching the surface, preventing the residues from reattaching. Residues that exceed this repulsive force and reach the adsorption layer are subjected to steric repulsion, which originates from the association of the water-soluble polymers and surfactants that make up the adsorption layer. This steric repulsion then prevents direct contact between the residues and the polished object. When the residues compress the adsorption layer, a decrease in coordination entropy occurs. The steric repulsion is thought to be caused by the osmotic pressure of the solvent resulting from the decrease in coordination entropy. Furthermore, the steric repulsion not only prevents the residues from directly contacting the polished object, but also facilitates their detachment from near the surface of the polished object. The ease of residue detachment can be measured as adhesion force using an atomic force microscope. Adhesion force refers to the adhesive strength between the probe of an atomic force microscope and the association of the water-soluble polymers and surfactants, and can be evaluated as the magnitude of the force required to detach the residues. In order to reduce the adhesive force, it is effective to increase the above-mentioned steric repulsion and to reduce the intermolecular force between the adsorption layer and the residue.

[0022] Typically, adhesion forces measured using an atomic force microscope (AFM) are influenced by surface shape and surface viscosity, in addition to steric repulsion and intermolecular forces. On the other hand, restoring adhesion is a force that strongly reflects intermolecular forces among the adhesion forces acting between the AFM probe and surfactant, and refers to the adhesion strength resulting from the intermolecular forces between the AFM probe and surfactant. By using a material similar to the residue at the tip of the probe, the probe can be considered as the residue. Therefore, the restoring adhesion force acting between the probe and surfactant can be said to be the adhesion strength acting between the residue and surfactant. Furthermore, surface roughness refers to the arithmetic mean roughness (Ra) of the surface of the adsorption layer formed by the surfactant as described above.

[0023] If the restoring adhesive force and surface roughness are within the above ranges, the residues are easily detached from the surfactant and are prevented from re-adhering to the surface of the polished object, so it is believed that the residues can be sufficiently removed. The recovery adhesive force may be greater than 0 N / m and less than 0.05 N / m, or greater than 0 N / m and less than 0.04 N / m. The surface roughness may be greater than 0 nm and less than 0.3 nm, or greater than 0 nm and less than 0.25 nm. Within these ranges, residues are more easily detached from the surfactant, making it even easier to remove the residues. The details of the methods for measuring the restoring adhesive force and the surface roughness will be described in the Examples below.

[0024] (surfactant) The post-CMP cleaning composition according to one embodiment of the present invention contains a surfactant. The type of surfactant is not particularly limited, and may be at least one of amphoteric, cationic, nonionic, and anionic surfactants. Examples of amphoteric surfactants include lecithin, alkylamine oxides, alkylbetaines such as N-alkyl-N,N-dimethylammonium betaines, and sulfobetaines such as 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid and dodecyldimethyl(3-sulfopropyl)ammonium hydroxide.

[0025] Examples of cationic surfactants include amines such as laurylamine hydrochloride, quaternary ammonium salts such as domiphen bromide, decyltrimethylammonium bromide, and benzyldodecyldimethylammonium bromide, and pyridinium salts such as 1-dodecylpyridinium chloride and laurylpyridinium chloride.

[0026] Examples of nonionic surfactants include alkyl ether types such as hexaethylene glycol monododecyl ether, polyoxyethylene lauryl ether, and polyoxyethylene oleyl ether, alkyl phenyl ether types such as polyoxyethylene octylphenyl ether, alkyl ester types such as polyoxyethylene laurate, alkyl amine types such as polyoxyethylene lauryl amino ether, alkyl amide types such as polyoxyethylene lauric acid amide, polypropylene glycol ether types such as polyoxyethylene polyoxypropylene ether, alkanolamide types such as oleic acid diethanolamide, allyl phenyl ether types such as polyoxyalkylene allyl phenyl ether, and nonyl phenyl ether types such as polyethylene glycol mono-4-nonylphenyl ether. Other nonionic surfactants that can be used include monopalmitin, propylene glycol, ethylene glycol, monoethanolamine, alcohol ethoxylates, alkylphenol ethoxylates, and tertiary acetylene glycol.

[0027] Examples of anionic surfactants include carboxylic acid types such as sodium myristate, sodium palmitate, sodium stearate, sodium laurate, and potassium laurate; sulfate ester types such as sodium octyl sulfonate; phosphate ester types such as sodium monododecyl phosphate, lauryl phosphate, and sodium lauryl phosphate; sulfonic acid types such as sodium bis(2-ethylhexyl) sulfosuccinate, sodium dioctyl sulfosuccinate, and sodium dodecylbenzenesulfonate; and amino acid types such as sodium N-lauroyl sarcosinate. The surfactant may be used alone or in combination of two or more kinds. In addition, the surfactant may be a commercially available product or a synthetic product.

[0028] Among these surfactants, it is preferable to use at least one selected from the group consisting of 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid, dodecyldimethyl(3-sulfopropyl)ammonium hydroxide, domiphen bromide, decyltrimethylammonium bromide, 1-dodecylpyridinium chloride, benzyldodecyldimethylammonium bromide, hexaethylene glycol monododecyl ether, polyethylene glycol mono-4-nonylphenyl ether, monopalmitin, sodium bis(2-ethylhexyl) sulfosuccinate, sodium monododecyl phosphate, and sodium N-lauroylsarcosinate.

[0029] The lower limit of the surfactant concentration in the post-CMP cleaning composition may be 0.01 g / L or more, 0.05 g / L or more, 0.1 g / L or more, or even 0.3 g / L or more, relative to the post-CMP cleaning composition. The upper limit of the surfactant concentration in the post-CMP cleaning composition may be 10 g / L or less, 5 g / L or less, 3 g / L or less, or 1 g / L or less. Within these ranges, the adhesion between the polished surface and the residue is reduced, which tends to reduce the total amount of remaining residue. When the post-CMP cleaning composition contains two or more surfactants, the content of the surfactants refers to the total content of these surfactants.

[0030] (Water-soluble polymer) A post-CMP cleaning composition according to one embodiment of the present invention contains a water-soluble polymer. The water-soluble polymer may be a homopolymer or a copolymer, and may be a compound having a weight-average molecular weight (Mw) of 1,000 or more. The type of water-soluble polymer is not particularly limited, and may be at least one selected from amphoteric, cationic, nonionic, and anionic water-soluble polymers. When the water-soluble polymer is a copolymer, the copolymer may be in the form of a block copolymer, a random copolymer, a graft copolymer, or an alternating copolymer.

[0031] Examples of amphoteric water-soluble polymers include copolymers of a vinyl monomer having an anionic group and a vinyl monomer having a cationic group, and vinyl-based amphoteric polymers having a carboxybetaine group or a sulfobetaine group. Specific examples include acrylic acid / dimethylaminoethyl methacrylic acid copolymers and acrylic acid / diethylaminoethyl methacrylic acid copolymers. Examples of cationic water-soluble polymers include polyethyleneimine (PEI), polyvinylamine, polyallylamine, polyvinylpyridine, and cationic acrylamide polymers.

[0032] Examples of nonionic water-soluble polymers include polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyvinylpyrrolidone (PVP), polyacrylamide, poly-N-vinylacetamide (PNVA), polyamines, polyvinyl ethers (e.g., polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl isobutyl ether), polyglycerin, polyethylene glycol, polypropylene glycol, polysaccharides such as water-soluble cellulose (hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose), alginic acid polyhydric alcohol esters, water-soluble urea resins, dextrin derivatives, casein, etc. In addition to those having such main chain structures, graft copolymers having a nonionic polymer structure may also be used.

[0033] Examples of anionic water-soluble polymers include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polymethallyl sulfonic acid, poly(2-acrylamido-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, polyacrylic acid, and polymethacrylic acid.

[0034] As the water-soluble polymer, a copolymer of the water-soluble polymers exemplified above may be used. The water-soluble polymer may be used alone or in combination of two or more. In addition, the water-soluble polymer may be a commercially available product or a synthetic product. The water-soluble polymer may be a nonionic water-soluble polymer from the viewpoint of facilitating detachment from the polished object after rinse polishing. Polyvinyl alcohol, polyvinylpyrrolidone, and hydroxyethyl cellulose are particularly preferred as nonionic water-soluble polymers. That is, the water-soluble polymer may be at least one selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, and hydroxyethyl cellulose.

[0035] The lower limit of the weight-average molecular weight (Mw) of the water-soluble polymer may be 1,000 or more, 1,500 or more, or 2,000 or more. The upper limit of the weight-average molecular weight of the water-soluble polymer may be 1,500,000 or less, 1,300,000 or less, or 1,000,000 or less. The weight-average molecular weight of the water-soluble polymer can be measured as a polyethylene glycol equivalent value using gel permeation chromatography (GPC).

[0036] The lower limit of the concentration of the water-soluble polymer in the post-CMP cleaning composition may be 0.1 g / L or more, 0.5 g / L or more, or 1.0 g / L or more. The upper limit of the concentration of the water-soluble polymer in the post-CMP cleaning composition may be 5.0 g / L or less, 3.0 g / L or less, or 2.0 g / L or less. Within these ranges, the post-CMP cleaning composition is more likely to be released from the surface of the polished object after rinse polishing. When the post-CMP cleaning composition contains two or more water-soluble polymers, the content of the water-soluble polymers refers to the total content of these.

[0037] (water) In the post-CMP cleaning composition according to this embodiment, water has the function of dispersing or dissolving each component, such as a water-soluble polymer, a surfactant, and other additives. Furthermore, from the viewpoint of preventing contamination of the polished object and inhibiting the action of other components, it is preferable to use water that contains as few impurities as possible. Specifically, pure water or ultrapure water, which has been filtered to remove impurity ions using an ion exchange resin, or distilled water, is preferred.

[0038] (pH adjuster) The pH of the post-CMP cleaning composition according to this embodiment is not particularly limited, but the lower limit may be 1 or more, 2 or more, 3 or more, or 4 or more. The upper limit may be 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, or 6 or less. Within these ranges, consumable components such as the polishing apparatus and the polishing pad in contact with the polishing apparatus are less likely to deteriorate, and residues and scratches caused by deterioration products can be prevented. The pH of the post-CMP cleaning composition can be confirmed using a pH meter.

[0039] The pH of the post-CMP cleaning composition may be adjusted using a pH adjuster. The pH adjuster is not particularly limited, and any known pH adjuster used in the field of post-CMP cleaning compositions can be used. Examples of pH adjusters that can be used include known acids, bases, and salts thereof.

[0040] Examples of acids that can be used as pH adjusters include organic acids and inorganic acids. Specific examples of organic acids that can be used as pH adjusters include carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid, lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, aconitic acid, amino acids, and anthranilic acid, as well as sulfonic acids and organic phosphonic acids. Specific examples of inorganic acids include nitric acid, carbonic acid, hydrochloric acid, phosphoric acid, hypophosphorous acid, phosphorous acid, phosphonic acid, boric acid, hydrofluoric acid, orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, metaphosphoric acid, and hexametaphosphoric acid.

[0041] Examples of bases used as pH adjusters include alkali metal hydroxides or salts thereof, alkaline earth metal hydroxides or salts thereof, quaternary ammonium hydroxides or salts thereof, ammonia, amines, etc. Specific examples of alkali metals include potassium and sodium. Specific examples of alkaline earth metals include calcium and strontium. Specific examples of salts include carbonates, bicarbonates, sulfates, acetates, etc. Furthermore, specific examples of quaternary ammonium include tetramethylammonium, tetraethylammonium, tetrabutylammonium, etc.

[0042] Specific examples of quaternary ammonium hydroxide compounds include quaternary ammonium hydroxide or salts thereof, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, etc. Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl)piperazine, N-methylpiperazine, guanidine, etc. The pH adjuster may be used alone or in combination of two or more. The pH adjuster may be a synthetic product or a commercially available product.

[0043] (Other additives) The post-CMP cleaning composition according to this embodiment may further contain known additives, such as abrasive grains, oxidizers, thickeners, dispersants, surface protectants, wetting agents, and solubilizers, as long as the effects of the present invention are not impaired. The content of the additives can be appropriately determined depending on the purpose of their addition. However, since components other than the essential components of the post-CMP cleaning composition according to the present invention may cause residues, it is desirable to avoid their inclusion as much as possible, and it is desirable to keep their content as low as possible.

[0044] <Method of Manufacturing Post-CMP Cleaning Composition> The method for producing the post-CMP cleaning composition according to this embodiment is not particularly limited. For example, the post-CMP cleaning composition according to the present invention can be obtained by stirring and mixing water, a water-soluble polymer, a surfactant, and, if necessary, other additives. The temperature at which the components are mixed is not particularly limited, but is preferably 10°C or higher and 40°C or lower, and heating may be used to increase the dissolution rate. The mixing time is also not particularly limited, as long as the components are mixed uniformly.

[0045] <Post-CMP cleaning method> Another aspect of the present invention is a method for post-CMP cleaning of a polished object having a layer containing a silicon-containing material using the above-mentioned post-CMP cleaning composition, comprising contacting the surface of the polished object having the layer containing a silicon-containing material with the post-CMP cleaning composition to form a surface treatment layer containing water, a water-soluble polymer, and a surfactant on the surface of the polished object having the layer containing a silicon-containing material. The surface treatment layer has an adsorption layer formed by adsorption of the surfactant on the surface of the polished object having the layer containing a silicon-containing material, and when observed with an atomic force microscope, the restoring adhesion force acting between the surfactant in the surface treatment layer and a probe of the atomic force microscope having a tip curvature radius of 2 nm to 12 nm is greater than 0 N / m and not greater than 0.07 N / m, and the surface roughness of the adsorption layer is greater than 0 nm and not greater than 0.4 nm.

[0046] In this specification, the post-CMP cleaning method refers to a method for reducing residues on the surface of a polished object, and is a cleaning method in a broad sense. According to one aspect of the post-CMP cleaning method of the present invention, residues remaining on the surface of a polished object can be effectively removed.

[0047] A post-CMP cleaning method according to one embodiment of the present invention is carried out by directly contacting a post-CMP cleaning composition with the surface of a polished object. There are no particular limitations on the post-CMP cleaning, but it is preferably carried out by, for example, a rinse polishing process or a cleaning process. The rinse polishing process and the cleaning process are carried out to remove foreign matter from the surface of the polished object and obtain a clean surface.

[0048] Rinse polishing is performed on a polishing table (platen) equipped with a polishing pad after the final polishing (finish polishing) of the object to be polished, with the aim of removing foreign matter from the surface of the object to be polished. At this time, the frictional force (physical action) of the polishing pad and the action of the post-CMP cleaning composition form a surface treatment layer containing water, a water-soluble polymer, and a surfactant on the surface of the polished object to be polished, and residues on the surface of the polished object to be polished are removed.

[0049] The polishing apparatus can be a general polishing apparatus equipped with a holder for holding the object to be polished, a motor with a variable rotation speed, and a polishing platen to which a polishing pad (polishing cloth) can be attached. The polishing apparatus may be either a single-side polishing apparatus or a double-side polishing apparatus. When the CMP treatment and the rinse polishing treatment are performed using the same polishing apparatus, the polishing apparatus preferably has a nozzle for discharging the post-CMP cleaning composition according to one embodiment of the present invention in addition to a nozzle for discharging the polishing composition. The polishing pad can be made of any material, including general nonwoven fabric, polyurethane, porous fluororesin, etc. The polishing pad is preferably provided with grooves for collecting the polishing liquid.

[0050] The rinse polishing conditions are not particularly limited, and can be appropriately set depending on the properties of the post-CMP cleaning composition and the polished object. The pressure (polishing pressure) applied to the polished object during rinse polishing may be 0.5 psi (3.4 kPa) or more and 10 psi (68.9 kPa) or less. The polishing time during rinse polishing is not particularly limited. Generally, the lower limit of the polishing time during rinse polishing may be 5 seconds or more, 10 seconds or more, 15 seconds or more, or 20 seconds or more. Furthermore, the upper limit of the polishing time during rinse polishing may be 180 seconds or less, 150 seconds or less, 120 seconds or less, or 100 seconds or less, from the viewpoint of efficiently removing residues.

[0051] The rotation speed of the platen during rinse polishing is not particularly limited. Generally, the lower limit of the rotation speed of the platen during rinse polishing is 10 rpm (0.17 s -1 ) or more, and -1 ) or more, and -1 ) or more. The upper limit of the rotation speed of the platen during rinse polishing is 500 rpm (8.3 s -1 ) or less, and -1 ) or less, and -1 ) or less.

[0052] The method for supplying the post-CMP cleaning composition in rinse polishing is not particularly limited, and a method of continuously supplying (flowing) using a pump or the like may be employed. The supply amount of the post-CMP cleaning composition (flow rate of the post-CMP cleaning composition) is not particularly limited as long as it is a supply amount that covers the entire polished object, but may generally be 100 mL / min or more and 5000 mL / min or less.

[0053] In this specification, the cleaning process refers to a process performed after the polished object has been removed from the polishing table, in which residues on the surface of the polished object are removed mainly by the chemical action of a post-CMP cleaning composition.

[0054] A specific example of the cleaning treatment is a treatment in which the polished object is removed from the polishing platen after the final polishing (finish polishing) treatment of the object to be polished, or after the final polishing followed by a rinse polishing treatment, and the polished object is brought into contact with the post-CMP cleaning composition. In the contact state between the post-CMP cleaning composition and the polished object to be polished, a means for applying a frictional force (physical action) to the surface of the polished object to be polished may be further used.

[0055] The cleaning treatment method, cleaning treatment device, and cleaning treatment conditions are not particularly limited, and known methods, devices, conditions, etc. can be used as appropriate. The cleaning treatment method is not particularly limited, and examples thereof include a method in which a polished object to be polished is immersed in a post-CMP cleaning composition and ultrasonic treatment is performed as necessary, and a method in which a cleaning brush is brought into contact with the polished object to be polished while holding the polished object, and the surface of the polished object to be polished is scrubbed with the brush while supplying the post-CMP cleaning composition to the contact area.

[0056] Before or after the post-CMP cleaning method according to one embodiment of the present invention, cleaning with water may be performed, or both. After that, water droplets adhering to the surface of the polished object may be removed by a spin dryer, an air blower, or the like, and the object may be dried.

[0057] In a post-CMP cleaning method according to one embodiment of the present invention, when observed using an atomic force microscope, the restoring adhesive force acting between a probe having a tip curvature radius of 2 nm to 12 nm and a surfactant in a surface treatment layer formed on a polished object having a layer containing a silicon-containing material is greater than 0 N / m and less than 0.07 N / m, and the surface roughness of the adsorption layer is greater than 0 nm and less than 0.4 nm. The restoring adhesive force and surface roughness are the same as those of the post-CMP cleaning composition described above. The details of the methods for measuring the restoring adhesive force and the surface roughness will be described in the Examples below. [Example]

[0058] Examples and comparative examples of the present invention will be described below, but the present invention is not limited to the examples shown below. Unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass," respectively. In the following examples, unless otherwise specified, operations were carried out at room temperature (25°C) and at a relative humidity of 40% RH or higher and 50% RH or lower.

[0059] Preparation of Post-CMP Cleaning Composition Example 1 The post-CMP cleaning composition of Example 1 was prepared by mixing and stirring for 5 minutes polyvinyl alcohol (PVA, weight-average molecular weight (Mw): 10,000) as a water-soluble polymer, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid as a surfactant, 1-hydroxyethane-1,1-diphosphonic acid (HEDP) as a pH adjuster, and water (deionized water) as a solvent. The concentration of the water-soluble polymer in the post-CMP cleaning composition was 1.5 g / L, and the concentration of the surfactant was 0.5 g / L.

[0060] (Examples 2 to 12 and Comparative Examples 4 and 5) Post-CMP cleaning compositions of Examples 2 to 12 and Comparative Examples 4 and 5 were prepared in the same manner as in Example 1, except that the types of water-soluble polymer and surfactant were changed to those listed in Table 1. Among the water-soluble polymers listed in Table 1, "PVP" represents polyvinylpyrrolidone with a weight-average molecular weight of 45,000, and "HEC" represents hydroxyethyl cellulose with a weight-average molecular weight of 1,400,000.

[0061] (Comparative Examples 1 to 3) Post-CMP cleaning compositions of Comparative Examples 1 to 3 were prepared in the same manner as in Example 1, except that the type of water-soluble polymer was changed to one listed in Table 1 and no surfactant was added. (Comparative Examples 6 and 7) Post-CMP cleaning compositions of Comparative Examples 6 and 7 were prepared in the same manner as in Example 1, except that the type of surfactant was changed to one listed in Table 1 and no water-soluble polymer was added. (Comparative Example 8) Deionized water served as the post-CMP cleaning composition for Comparative Example 8.

[0062] (Measurement of pH of post-CMP cleaning compositions) The pH of the post-CMP cleaning compositions of Examples 1 to 12 and Comparative Examples 1 to 8 was confirmed using a pH meter (manufactured by Horiba, Ltd., product name: LAQUA (registered trademark)).

[0063] <Preparing the polished object> A polished object was prepared after being polished by the following CMP process. (CMP process) A silicon wafer with a diameter of 300 mm and a silicon nitride (SiN) film with a thickness of 10,000 Å was prepared as the object to be polished. The silicon nitride film-coated silicon wafer prepared above was polished using a polishing composition (composition: 4% colloidal silica (average primary particle size 30 nm, average secondary particle size 60 nm) and 0.018% aqueous maleic acid solution with a concentration of 30%, solvent: water) with the following equipment and conditions. After polishing the surface of the silicon nitride film-coated silicon wafer, the resulting polished object was removed from the polishing platen.

[0064] Polishing equipment: Ebara Corporation 300mm CMP single-sided polishing equipment FREX300E Polishing pad: Fujibo Holdings Co., Ltd. H800 foam polyurethane pad Polishing pressure: 2.0 psi (1 psi = 6894.76 Pa) Polishing platen rotation speed: 80 rpm Head rotation speed: 80 rpm Polishing compound supply: free-flowing ·Polishing composition supply amount: 200mL / min Polishing time: 30 seconds

[0065] (Rinse polishing process) The obtained polished object was placed on another polishing platen in the same polishing apparatus, and the surface of the polished object was subjected to a rinse polishing treatment using the post-CMP cleaning compositions of Examples 1 to 12 and Comparative Examples 1 to 4 under the following conditions and with the following apparatus. Polishing equipment: Ebara Corporation 300mm CMP single-sided polishing equipment FREX300E Polishing pad: Fujibo Holdings Co., Ltd. H800 foam polyurethane pad Polishing pressure: 2.0 psi (1 psi = 6894.76 Pa) Polishing platen rotation speed: 60 rpm Head rotation speed: 60 rpm Post-CMP cleaning composition supply: flow-through Post-CMP cleaning composition supply rate: 300 mL / min Rinse polishing time: 10 seconds

[0066] <Evaluation> (Measurement of restoring adhesive force) After the rinse-polished polishing process, the rinse-polished polished objects were cut into 30mm squares. The recovery adhesive force acting between the probe of an atomic force microscope and the surfactant contained in the CMP cleaning composition was measured for the cut-out rinse-polished polished objects. The measurement results are shown in Table 1.

[0067] The recovery adhesion force was measured using an atomic force microscope (AFM) in PeakForceQNM and Ringing modes. In this mode, the AFM probe was first pressed into the surface of the rinsed and polished workpiece and then rapidly removed. By controlling the cantilever deflection, the probe was released from the surface of the rinsed and polished workpiece, but not adhered to the surfactant. As the probe then released from the surface of the rinsed and polished workpiece, the surfactant also separated from the probe. The recovery adhesion force, or the adhesion force between the probe and the surfactant, was measured by analyzing the cantilever's damped oscillation signal from the state where only the probe and surfactant were adhered to the surface to the state where the probe and surfactant were separated. Furthermore, by using a probe made of the same material as the residue, the probe could be considered as the residue. Therefore, the measured recovery adhesion force represents the adhesion force between the residue and the surfactant. The smaller the recovery adhesion force, the easier it is for the residue to detach from the surfactant.

[0068] The measurement device and conditions for measuring the restoring adhesive force are as follows: The measurement was carried out in water adjusted to the same pH as in each example and comparative example. Measurement equipment: AFM-IR Dimension icon-IR manufactured by Bruker Japan Co., Ltd. Probe:SCANASYST-FRUID+ Probe tip material: Si Tip curvature radius: 2nm Scanning frequency: 0.5Hz Scanning range: 100×100nm

[0069] [Table 1]

[0070] (Surface roughness measurement of adsorption layer surface) The rinse-polished polished specimens were each cut into 30mm squares, and the surface roughness of each was evaluated using an atomic force microscope. Specifically, a 100nm square area on the substrate was scanned with the atomic force microscope, and the arithmetic mean roughness (Ra) was measured. The measurement results are shown in Table 1.

[0071] The surface roughness was measured using the following equipment and under the following conditions: The measurements were carried out in water adjusted to the same pH as in each example and comparative example. Measurement equipment: AFM-IR Dimension icon-IR manufactured by Bruker Japan Co., Ltd. Probe:SCANASYST-FRUID+ Probe tip material: Si Tip curvature radius: 2nm Scanning frequency: 0.5Hz Scanning range: 100×100nm

[0072] (residue count measurement) Using a Surfscan® SP5 optical inspection machine manufactured by KLA-Tencor Corporation, the number of residues with a diameter of 65 nm or more remaining on the surface of the rinsed and polished workpieces that had been cleaned in the above cleaning process was measured. Note that a 5 mm section around the periphery of the rinsed and polished workpieces after cleaning was not included in the measurement. The results are shown in Table 1.

[0073] As shown in Table 1, in all of Examples 1 to 12, the number of residues remaining on the surface of the rinsed and polished object after cleaning was less than 200, while in all of Comparative Examples 1 to 8, the number was 200 or more. This indicates that the post-CMP cleaning compositions of Examples 1 to 12 have a higher ability to remove residues than the post-CMP cleaning compositions of Comparative Examples 1 to 8.

[0074] The results of Examples 1 to 12 and Comparative Examples 1 to 8 show that when a post-CMP cleaning composition contains both a water-soluble polymer and a surfactant, has a recovery adhesion force of more than 0 N / m and not more than 0.07 N / m, and has a surface roughness of more than 0 nm and not more than 0.40 nm, it can effectively remove residues remaining on the surface of a polished object.

[0075] Furthermore, for example, the present invention can have the following configuration. [1] A post-CMP cleaning composition used to clean a polished object that has been subjected to chemical mechanical polishing (CMP), comprising: Contains water, a water-soluble polymer, and a surfactant, When the surface of the polished object is covered with the post-CMP cleaning composition, when observed using an atomic force microscope, a restoring adhesion force acting between the surfactant and a probe having a tip curvature radius of 2 nm or more and 12 nm or less of the atomic force microscope is greater than 0 N / m and 0.07 N / m or less, A post-CMP cleaning composition in which the surface roughness of an adsorption layer formed by adsorption of the surfactant onto the surface of the polished object is greater than 0 nm and not greater than 0.4 nm.

[0076] [2] The post-CMP cleaning composition according to [1], further comprising a pH adjuster. [3] The post-CMP cleaning composition according to [1] or [2], wherein the water-soluble polymer is at least one selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, and hydroxyethyl cellulose.

[0077] [4] The post-CMP cleaning composition according to any one of [1] to [3], wherein the surfactant is at least one selected from the group consisting of 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid, dodecyldimethyl(3-sulfopropyl)ammonium hydroxide, domiphen bromide, decyltrimethylammonium bromide, 1-dodecylpyridinium chloride, benzyldodecyldimethylammonium bromide, hexaethylene glycol monododecyl ether, polyethylene glycol mono-4-nonylphenyl ether, monopalmitin, sodium bis(2-ethylhexyl)sulfosuccinate, sodium monododecyl phosphate, and sodium N-lauroylsarcosinate.

[0078] [5] A method for post-CMP cleaning of a polished object having a layer containing a silicon-containing material, using the post-CMP cleaning composition according to any one of [1] to [4], comprising: The post-CMP cleaning method includes: contacting the surface of a polished object having a layer containing a silicon-containing material with the post-CMP cleaning composition to form a surface treatment layer containing the water, the water-soluble polymer, and the surfactant on the surface of the polished object having a layer containing a silicon-containing material; the surface treatment layer has an adsorption layer formed by adsorption of the surfactant on a surface of the polished object having a layer containing the silicon-containing material, when observed using the atomic force microscope, a restoring adhesion force acting between a probe of the atomic force microscope, the tip of which has a curvature radius of 2 nm or more and 12 nm or less, and the surfactant in the surface treatment layer is greater than 0 N / m and 0.07 N / m or less, A post-CMP cleaning method, wherein the surface roughness of the surface of the adsorption layer is greater than 0 nm and not greater than 0.4 nm.

Claims

1. A post-CMP cleaning composition used to clean a polished object that has been subjected to chemical mechanical polishing (CMP), comprising: Contains water, a water-soluble polymer, and a surfactant, When the surface of the polished object is covered with the post-CMP cleaning composition, when observed using an atomic force microscope, a restoring adhesion force acting between the surfactant and a probe provided on the atomic force microscope, the probe having a tip curvature radius of 2 nm or more and 12 nm or less, is greater than 0 N / m and 0.07 N / m or less; A post-CMP cleaning composition in which the surface roughness of an adsorption layer formed by adsorption of the surfactant onto the surface of the polished object is greater than 0 nm and not greater than 0.40 nm.

2. The post-CMP cleaning composition of claim 1 further comprising a pH adjuster.

3. 3. The post-CMP cleaning composition according to claim 1, wherein the water-soluble polymer is at least one selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, and hydroxyethyl cellulose.

4. The post-CMP cleaning composition according to claim 1 or 2, wherein the surfactant is at least one selected from the group consisting of 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid, dodecyldimethyl(3-sulfopropyl)ammonium hydroxide, domiphen bromide, decyltrimethylammonium bromide, 1-dodecylpyridinium chloride, benzyldodecyldimethylammonium bromide, hexaethylene glycol monododecyl ether, polyethylene glycol mono-4-nonylphenyl ether, monopalmitin, sodium bis(2-ethylhexyl)sulfosuccinate, sodium monododecyl phosphate, and sodium N-lauroylsarcosinate.

5. A method for post-CMP cleaning of a polished object having a layer containing a silicon-containing material using the post-CMP cleaning composition according to claim 1 or 2, comprising: The post-CMP cleaning method includes: contacting the surface of a polished object having a layer containing a silicon-containing material with the post-CMP cleaning composition to form a surface treatment layer containing the water, the water-soluble polymer, and the surfactant on the surface of the polished object having a layer containing a silicon-containing material; the surface treatment layer has an adsorption layer formed by adsorption of the surfactant on a surface of the polished object having a layer containing the silicon-containing material, when observed using the atomic force microscope, a restoring adhesion force acting between a probe having a tip curvature radius of 2 nm or more and 12 nm or less and the surfactant in the surface treatment layer is greater than 0 N / m and 0.07 N / m or less, A post-CMP cleaning method, wherein the surface roughness of the surface of the adsorption layer is greater than 0 nm and not greater than 0.4 nm.

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