WO2016035346A1 - Slurry composition, rinse composition, substrate polishing method and rinsing method - Google Patents

Slurry composition, rinse composition, substrate polishing method and rinsing method Download PDF

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Publication number
WO2016035346A1
WO2016035346A1 PCT/JP2015/004504 JP2015004504W WO2016035346A1 WO 2016035346 A1 WO2016035346 A1 WO 2016035346A1 JP 2015004504 W JP2015004504 W JP 2015004504W WO 2016035346 A1 WO2016035346 A1 WO 2016035346A1
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Prior art keywords
water
polishing
soluble polymer
present
slurry composition
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PCT/JP2015/004504
Other languages
French (fr)
Inventor
Tsuyoshi Masuda
Hiroshi Kitamura
Yoshiyuki Matsumura
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Nihon Cabot Microelectronics K.K.
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Application filed by Nihon Cabot Microelectronics K.K. filed Critical Nihon Cabot Microelectronics K.K.
Priority to KR1020177008862A priority Critical patent/KR102524838B1/en
Priority to CN201580047704.7A priority patent/CN107075309B/en
Publication of WO2016035346A1 publication Critical patent/WO2016035346A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09G—POLISHING COMPOSITIONS; SKI WAXES
    • C09G1/00—Polishing compositions
    • C09G1/02—Polishing compositions containing abrasives or grinding agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
    • B08B3/04—Cleaning involving contact with liquid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09G—POLISHING COMPOSITIONS; SKI WAXES
    • C09G1/00—Polishing compositions
    • C09G1/04—Aqueous dispersions
    • C—CHEMISTRY; METALLURGY
    • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
    • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
    • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
    • C11D3/16—Organic compounds
    • C11D3/37—Polymers
    • C11D3/3746—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • C11D3/3753—Polyvinylalcohol; Ethers or esters thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting

Definitions

  • the present invention relates to a technology for polishing semiconductor substrates, and more particularly, relates to a slurry composition, a rinse composition, a substrate polishing method and a rinsing method used in chemical mechanical polishing (CMP) and the like.
  • CMP chemical mechanical polishing
  • Semiconductor substrates in the form of silicon wafers used in the production of semiconductor devices are used to supply semiconductor devices after being subjected to various types of photolithography, deposition treatment, polishing treatment and the like. Numerous processing steps are applied to silicon wafers in order to fabricate semiconductor devices, and since it also necessary to improve the yield of semiconductor devices, the surface quality of silicon wafers is subject to strict requirements. Chemical mechanical polishing (CMP) has been conventionally used to ensure surface quality by mirror-polishing silicon wafers.
  • CMP Chemical mechanical polishing
  • the silicon wafer When using CMP to polish silicon wafers, the silicon wafer is typically held on a carrier for immobilizing the silicon wafer, the silicon wafer is then interposed between upper and lower surface plates having abrasive cloths affixed thereto that contain synthetic resin foam or suede-like artificial leather and the like, and the silicon wafer is then polished while being pressed and rotated while supplying an aqueous composition comprising a dispersion of silica, alumina, ceria, zirconia or other colloidal particles (to be subsequently referred to as a slurry composition).
  • an aqueous composition comprising a dispersion of silica, alumina, ceria, zirconia or other colloidal particles (to be subsequently referred to as a slurry composition).
  • Japanese Unexamined Patent Publication No. 2014-38906 (PTL 1) describes a polishing composition that comprises a polyvinyl alcohol for the backbone structure for the purpose of inhibiting adherence of particles to the polished surface of a polishing target.
  • Japanese Unexamined Patent Publication No. H11-140427 (PTL 2) describes a polishing liquid, containing a linear hydrocarbon-based polymer having a carbon long chain backbone and hydroxy-lower alkylene groups in a side chain thereof, and a polishing method using the same.
  • an object of the present invention is to provide a slurry composition, rinse composition, substrate polishing method and rinsing method that make it possible to improve the surface state of semiconductor substrates.
  • a slurry composition for chemical mechanical polishing comprises water, abrasive grains and one or more water-soluble polymer containing a polyvinyl alcohol structural unit.
  • the aforementioned water-soluble polymer can be a one or more a water-soluble polymer respectively containing a polyoxyalkylene oxide structural unit or polyvinyl alcohol structural unit.
  • the polyoxyalkylene oxide structural unit or the polyvinyl alcohol structural unit thereof is able to form a backbone or side chain of the water-soluble polymer.
  • the water-soluble polymer preferably contains a pH adjuster.
  • the present invention can contain a water-soluble polymer selected from a cellulose-based polymer and polyalkylene oxide-based polymer.
  • the present invention can also contain a haze improver.
  • the water-soluble polymer is preferably contained at 1 ppm to 5000 ppm.
  • a rinse composition for a polishing substrate comprises water and one or more water-soluble polymer containing a polyvinyl alcohol structural unit.
  • the aforementioned water-soluble polymer can be one or more a water-soluble polymer respectively containing a polyalkylene oxide structural unit or polyvinyl alcohol structural unit.
  • the aforementioned polyalkylene oxide structural unit and polyvinyl alcohol structural unit thereof can form a backbone or side chain of the water-soluble polymer.
  • the present invention can contain a water-soluble polymer selected from a cellulose-based polymer and polyalkylene oxide-based polymer.
  • the present invention can further contain a haze improver.
  • the water-soluble polymer is preferably contained at 1 ppm to 5000 ppm.
  • a substrate polishing method comprises a step for adhering the previously described slurry composition to a polishing substrate, and a step for polishing the polishing substrate with a polishing pad using the slurry composition.
  • a polishing substrate rinsing method comprises a step for rinsing a polishing substrate with the previously described rinse composition.
  • a slurry composition, rinse composition, substrate polishing method and rinsing method are provided that make it possible to improve microscopic surface irregularities, or in other words, nanoscale polishing defects, referred to as, for example, light point defects (LPD), haze, haze scratches or haze lines and the like.
  • LPD light point defects
  • haze haze scratches or haze lines and the like.
  • the slurry composition or rinse composition of the present invention comprises one or more water-soluble polymer respectively containing a polyalkylene oxide structural unit and a polyvinyl alcohol structural unit.
  • the slurry composition or rinse composition of the present invention comprises one or more water-soluble polymer respectively containing a polyalkylene oxide structural unit and a polyvinyl alcohol structural unit.
  • two different polyoxyalkylene oxide and polyvinyl alcohol water-soluble polymers may be contained and formed in each composition.
  • the polyalkylene structural unit or the polyvinyl alcohol structural unit may be present in each composition in the form of a graft polymer that composes a backbone chain or side chain.
  • a portion of the hydroxyl groups may be substituted with an acyloxy group.
  • Acyloxy groups having two or more carbon atoms can be preferably used for the acyloxy group, and a (CH 3 COO-) group is particularly preferable.
  • the polyoxyalkylene oxide in the polyalkylene oxide structural unit can be polyethylene oxide, polypropylene oxide or an (ethylene oxide-propylene oxide) copolymer, and the copolymer may be a random copolymer or block copolymer.
  • the repeating chain length of the alkylene oxide of the polyalkylene oxide is 1 to 1000, more preferably 2 to 300 and even more preferably about 3 to 200.
  • the abundance ratio thereof in terms of mol% is preferably 5:95 to 40:60, and from the viewpoint of improving nanoscale polishing defects, can be within the range of 10:90 to 30:70.
  • the molecular weight of the polyalkylene oxide and polyvinyl alcohol can be within the range of 1,000 to 10,000,000.
  • the molecular weight of the graft polymer can be such that the weight average molecular weight is 5,000 to 500,000, and in consideration of the rheological properties of a solution such as a slurry solution, the weight average molecular weight can be preferably within the range of 10,000 to 300,000 and more preferably within the range of 10,000 to 200,000.
  • the abundance ratio of the polyalkylene oxide backbone to the polyvinyl alcohol backbone in a graft polymer of the present embodiment in terms of mol% is preferably 5:95 to 40:60, and from the viewpoint of improving nanoscale polishing defects, is preferably within the range of 10:90 to 30:70.
  • the alkylene oxide backbone of the present embodiment can be ethylene oxide, propylene oxide or can form a chain by random polymerization or block polymerization thereof.
  • the alkylene oxide is most preferably ethylene oxide.
  • a specific example of the water-soluble polymer may be a water-soluble polymer having the general formula (1) indicated below.
  • R represents a hydroxyl group or acyloxy group having two or more carbon atoms
  • a represents an integer of 1 to 10,000
  • M1, M2, N1 and N2 represent a real number of 0 or more (grating rate).
  • R 1 represents a hydrogen atom or acyl group.
  • R 2 and R 3 may be the same or different and represent a linear or branched alkyl group having two or more carbon atoms
  • b represents an integer of 2 to 10,000.
  • R in the aforementioned general formulas (1) and (1') may have a mixed structure in which both a hydroxyl group and acyloxy group are present, namely, a structure in which an acyloxy group has been saponified to a hydroxyl group.
  • preferable water-soluble polymers in the present embodiment include water-soluble polymers having the structural formulas (2) and (3) indicated below. Furthermore, a portion or terminal hydroxyl group of the hydroxyl groups of the following general formulas (2) and (3) may be substituted with an acyloxy group.
  • the aforementioned water-soluble polymer can be present in the slurry composition within a range of 1 ppm (0.001% by weight) to 5000 ppm (0.5% by weight).
  • the water-soluble polymer is preferably added within the range of 10 ppm to 1000 ppm from the viewpoint of maintaining a polishing speed that enables realistic production throughput.
  • the slurry composition of the present embodiment can contain a polymer having a tertiary amine structure in the main chain structure thereof for use as a haze improver for improving LPD and haze on a semiconductor substrate surface.
  • the aforementioned polymer used in the present invention can be produced by addition polymerization of an alkylene oxide at least containing ethylene oxide with an active hydrogen of a polyamine compound having two or more primary amino groups and/or a secondary amino groups and containing 4 to 100 N atoms in a molecule thereof.
  • the weight average molecular weight of the polymer can be within the range of 5,000 to 100,000.
  • the number of N atoms contained in the polymer of the present embodiment is preferably 2 to 10,000 or less from the viewpoint of providing water solubility in order to apply to a CMP process, and the number of N atoms is preferably within the range of 2 to 1,000 from the viewpoint of providing adequate CMP process compatibility while improving haze.
  • this polymer is referred to as an alkylene-polyalkylene oxide amine polymer (APOA).
  • polyamine compounds that impart a main chain structure in the present embodiment may include polyethylene polyamines such as triethylene tetraamine, tetraethylene pentamine, pentaethylene hexamine or hexaethylene heptamine, and polyalkylene imines such as polyethylene imine obtained by polymerization of ethylene imine.
  • polyethylene polyamines such as triethylene tetraamine, tetraethylene pentamine, pentaethylene hexamine or hexaethylene heptamine
  • polyalkylene imines such as polyethylene imine obtained by polymerization of ethylene imine.
  • the aforementioned compounds can be used alone or two or more can be used in combination to form a polyamine main chain structure of the present embodiment.
  • alkylene oxides added to the aforementioned main chain structure include ethylene oxide, propylene oxide and butylene oxide, and these alkylene oxides can be used alone or as a mixture of a plurality thereof.
  • the alkylene oxide backbone able to be used in the present embodiment is preferably selected from an ethylene oxide backbone and/or a polypropylene backbone.
  • the ratio of ethylene oxide in the alkylene oxide added to the polymer of the present embodiment is 5% or more and preferably 10% or more, and by making this ratio of be 50% to 90%, preferable CMP process compatibility can be imparted.
  • containing a propylene oxide backbone in the present embodiment containing within a range of 10% to 20% is similarly preferable in terms of widening the process margin.
  • the polymer of the present embodiment can be easily produced by an ordinary method.
  • the polymer of the present embodiment can be produced by addition polymerization (graft polymerization) of an alkylene oxide with a starting substance in the form of the aforementioned polyamine compound at a temperature of 100°C to 180°C and atmospheric pressure of 1 atm to 10 atm in the presence of an alkaline catalyst.
  • the addition mode of the alkylene oxide to the main chain structure in the form of the polyamine compound there are no particular limitations on the addition mode of the alkylene oxide to the main chain structure in the form of the polyamine compound, and in the case of a mode in which two or more alkylene oxides are added, the addition mode may be in the form of block addition or random addition.
  • the weight average molecular weight of the polymer of the present embodiment can be 5,000 or more and preferably 10,000 or more, and can be made to be within the range of 100,000 or less and 80,000 or less. In the case the weight average molecular weight is excessively low, haze cannot be adequately improved, while in the case weight average molecular weight is excessively high, the dependency of each property on the added amount increases, thereby narrowing the process margin and making this undesirable.
  • the main chain structure in the present specification refers to a structure containing two or more repeating structural units that contain a tertiary amine that causes graft polymerization of a polyalkylene oxide group.
  • the tertiary amine that composes the main chain structure of the present embodiment preferably contains an N-alkylene group.
  • N-alkylene group There are no particular limitations on the number of C atoms that compose the N-alkylene group, and a linear or branched alkylene group can be selected that has a number of C atoms within the range of 2 to 10.
  • a specific example of the polymer of the present embodiment may be exemplified as a polymer represented by the following general formula (4) that is formed by addition polymerization of an alkylene oxide with a polyethylene polyamine, and at least contains a tertiary amine structure in the main chain structure thereof.
  • x and y represent positive integers and R 4 represents an alkylene group.
  • R 3 and R 4 represent linear or branched alkylene groups having two or more carbon atoms, and are most preferably ethylene groups from the viewpoints of improving productivity, cost performance and haze.
  • x can be within the range of 2 to 1,000 and preferably within the range of 2 to 20, while y can be within the range of 2 to 10,000 and preferably within the range of 2 to 500. If the chain length of the R 4 O chain is excessively long, the effect of improving surface properties decreases, while if y is 10,000 or more, the dependency of each property on the added amount increases, thereby having a detrimental effect on process margin.
  • R 4 O can be formed using two or more alkylene oxides, and in the case of the present embodiment, different alkylene oxide groups may be in block form or random form.
  • solubility parameter of those compounds given in the aforementioned formulas (1) to (4) in the present invention is preferably made to be within the range of 9 to 16.
  • solubility parameter (SP) refers to the SP value of a water-soluble polymer based on the SP value of the monomer as determined according to the method of Fedors described in Ueda, et al., "Research on Coatings", No. 152, October 2010, pp. 41-46.
  • water-soluble polymers can be used in combination in the present invention.
  • water-soluble polymers may include homopolymers or copolymers formed by polymerizing a vinyl monomer.
  • vinyl monomers include water-soluble polymers or copolymers that are homopolymers and arbitrary combinations of copolymers of styrene, chlorostyrene, ⁇ -methylstyrene, divinylbenzene; vinyl carboxylates such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl stearate, vinyl adipate, vinyl (meth)acrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate or vinyl cinnamate, acrylonitrile, limonene, cyclohexene; N-vinyl compounds such as 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, N-vinyl
  • cellulose derivatives such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose or hydroxypropylmethyl cellulose can be used in the present invention.
  • Cellulose derivatives having an average molecular weight of 50,000 to 2,000,000 can be used.
  • water-soluble polymers that can be used in combination may include poly-N-vinylpyrrolidone, poly-N-vinylacetoamide, polyglycerin, PEG/PEO having a molecular weight of 1,000 to 1,000,000, PEG-PPG block copolymers, alkylene oxide ethylenediamine adducts (EO weight ratio: 35%, PPG molecular weight: 4400, reverse type), poly-(2-ethyloxazoline) (average molecular weight: 500,000), polyvinyl alcohol (average molecular weight: 200,000), polyacrylic acid (average molecular weight: 25,000) and polyacrylate (average molecular weight: 5,000).
  • PEG/PEO having a molecular weight of 1,000 to 1,000,000
  • PEG-PPG block copolymers alkylene oxide ethylenediamine adducts (EO weight ratio: 35%, PPG molecular weight: 4400, reverse type
  • poly-(2-ethyloxazoline) average molecular weight:
  • the added amount thereof can be within the range of 1 ppm (0.001% by weight) to 5000 ppm (0.5% by weight).
  • the added amount is preferably within the range of 5 ppm to 1000 ppm from the viewpoint of maintaining a silicon wafer polishing speed that enables realistic production throughput, and is more preferably within the range of 5 ppm to 500 ppm from the viewpoint of not requiring other adjustments of the slurry composition.
  • the slurry composition of the present invention can contain polishing components such as abrasive grain, acid or base, buffer, catalyst or various types of salts.
  • polishing components such as abrasive grain, acid or base, buffer, catalyst or various types of salts.
  • Abrasive grain typically used for polishing can be used for the abrasive grain used in the present invention.
  • abrasive grain may include metals, metallic or semi-metallic carbides, nitrides, oxides, borides and diamonds.
  • the abrasive grain able to be used in the present invention is preferably a metal oxide capable of polishing a substrate surface without introducing harmful scratches (marks) or other defects on the substrate surface.
  • metal oxide abrasive grain may include alumina, silica, titania, ceria, zirconia, magnesia, products co-formed therefrom, mixtures thereof, and chemical mixtures thereof.
  • the abrasive grain is typically selected from the group consisting of alumina, ceria, silica, zirconia and combinations thereof. Silica, and particularly colloidal silica and ceria, are preferable abrasive grains, while colloidal silica is more preferable.
  • the abrasive grain of the slurry composition of the present invention can be formed in the form of a dispersion or suspension by dispersing the abrasive grain in a preferable liquid carrier and adding various types of additives such as a water-soluble polymer.
  • the slurry composition is produced at a higher concentration than the concentration at which it is used for polishing for the purpose of reducing transport cost.
  • all locations describing the concentration of the slurry composition refer to the concentration after it has been diluted as a polishing liquid used for polishing.
  • preferable liquid carriers may include polar solvents, and preferably water or an aqueous solvent, and in the case the abrasive grain is contained in a slurry, the slurry preferably contains the abrasive grain at a concentration at the time of polishing of 0.1% by weight or more and more preferably 0.1% by weight to 50% by weight, and even more preferably, abrasive grain in the form of colloidal silica can be added to the slurry composition at 0.1% by weight to 10% by weight.
  • the pH of the slurry composition of the present invention can be suitably adjusted in consideration of polishing speed.
  • the pH of the slurry composition is preferably within the range of 5 to 12, and more preferably within the range of 7 to 12 in the case of carrying out polishing treatment on a silicon wafer.
  • the average particle diameter of primary particles of the abrasive grain is preferably 0.01 ⁇ m to 3 ⁇ m, more preferably 0.01 ⁇ m to 0.8 ⁇ m and particularly preferably 0.02 ⁇ m to 0.5 ⁇ m from the viewpoint of improving polishing speed.
  • the average particle diameter of the secondary particles can be preferably 0.02 ⁇ m to 3 ⁇ m, more preferably 0.05 ⁇ m to 1 ⁇ m and particularly preferably 0.03 ⁇ m to 0.15 ⁇ m from similar viewpoints of improving polishing speed and reducing surface roughness of the polished object.
  • the average particle diameter of primary particles of the abrasive grain can be determined by observing with a scanning electron microscope or transmission electron microscope, analyzing the resulting images and measuring particle diameter.
  • the average particle diameter of secondary particles can be measured as volume average particle diameter using the laser light scattering method.
  • additives can be used corresponding to the polishing substrate.
  • additives that can be present in the polishing system may include amines, ammonium salts, alkaline metal ions, film forming agents, complexing agents, surfactants, rheology control agents, polymeric stabilizers or dispersions and/or halide ions.
  • Additives can be present in the polishing system at an arbitrary preferable concentration.
  • an amine compound can be added to the slurry composition, and the amine compound can be selected from aliphatic amines, cyclic amines, heterocyclic amines, aromatic amines, polyamines and combinations thereof.
  • the amine compound can contain at least one oxygen atom and at least one polar moiety such as an amino acid or amino alcohol, and specific examples thereof may include dimethylpropanol amine, (also known as 2-dimethylamino-2-methyl-1-propanol or DMAMP), 2-amino-2-methyl-1-propanol (AMP), 2-(2-aminoethylamino)ethanol, 2-(isopropylamino)ethanol, 2-(methylamino)ethanol, 2-(diethylamino)ethanol, 2-(2-(dimethylamino)ethoxy)ethanol, 1,1'-[[3-(dimethylamino)propyl]imino]-bis-2-propanol, 2-(butylamino
  • an ammonium salt can be added in addition to an amine compound, and, for example, hydroxylated amines (such as tetramethylammonium hydroxide (TMAH)) and quaternary ammonium compounds can be used.
  • hydroxylated amines such as tetramethylammonium hydroxide (TMAH)
  • quaternary ammonium compounds can be used.
  • Alkaline metal ions may also be present in the slurry composition in the form of counter ions of various types of salts.
  • Preferable examples of alkaline metal ions may include monovalent base metals belonging to group 1 of the periodic table.
  • Specific examples of alkaline metal ions that can be used may include sodium ions, potassium ions, rubidium ions and cesium ions. Potassium ions and cesium ions are preferable, while potassium ions are more preferable.
  • an anticorrosive agent can be used together with the polishing system, and examples of anticorrosive agents may include alkylamines, alkanolamines, hydroxylamines, phosphate esters, sodium lauryl sulfate, fatty acids, polyacrylates, polymethacrylates, polyvinyl phosphonates, polymalates, polystyrene sulfonates, polyvinyl sulfonates, benzotriazole, triazole, benzimidazole and mixtures thereof.
  • a chelating agent and the like can be arbitrarily added to the slurry composition.
  • chelating agents may include carbonyl compounds such as acetylacetonate, carboxylates such as acetates or aryl carboxylate, carboxylates containing at least one hydroxyl group such as glycolates, lactates, glyconates or gallic acid and salts thereof, dicarboxylates, tricarboxylates and polycarboxylates such as oxalates, phthalates, citrates, succinates, tartrates, malates, edetates such as disodium EDTA, and mixtures thereof.
  • Preferable examples of chelating agents may include dialcohols, trialcohols or polyvalent alcohols such as ethylene glycol, pyrocatechol, pyrogallol or tannic acid, and phosphate-containing compounds.
  • a surfactant, viscosity modifier or coagulant can be arbitrarily used together with the polishing system.
  • viscosity modifiers may include urethane polymers and acrylates containing at least one acrylic unit.
  • Specific examples of viscosity modifiers may include low molecular weight carboxylates and high molecular weight polyacrylamide compounds, while preferable examples of surfactants may include cationic surfactants, anionic surfactants, anionic polyelectrolytes, nonionic surfactants, amphoteric surfactants, fluorinated surfactants and mixtures thereof.
  • a substrate can be polished with a polishing system provided with a suitable polishing pad.
  • a woven or non-woven polishing pad for example, can be preferably used for the polishing pad.
  • a specific example of a preferable polishing pad that can be used may be a synthetic resin polishing pad, and preferable examples of polymers used may include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, hydrogen fluoride, polycarbonate, polyester, polyacrylate, polyether, polyethylene, polyamide, polyurethane, polystyrene, polypropylene and co-formed products and mixtures thereof.
  • the slurry composition and substrate polishing method of the present invention can be applied to not only silicon substrates, but also to substrates to which polishing treatment can be applied, such as silicon substrates, sapphire substrates, SiC substrates, GaAs substrates, GaN substrates or TSV substrates having a polysilicon film, SiO 2 film or metal wiring film formed thereon.
  • the present invention can be applied to not only a method in which the slurry composition is prepared in advance followed by polishing with a polishing pad while supplying the prepared slurry composition to a polishing substrate, but also to a polishing method in which so-called on-platen formulation and preparation are carried out comprising supplying a diluent and undiluted slurry onto a polishing pad and preparing the slurry composition for substrate polishing in the vicinity of the polishing pad.
  • an aqueous solution containing water and a water-soluble polymer represented by general formula (1) can be used as a rinsing solution used to rinse a polishing substrate following polishing treatment.
  • the rinse composition of the present embodiment can be used after adding, in addition to water and the water-soluble polymer represented by general formula (1), various types of additives, excluding abrasive grain, such as a cellulose-based polymer, polyalkylene oxide polymer, other water-soluble polymers or a pH adjuster such as an acid or base.
  • the slurry composition of the present invention was fabricated by adding an additive having the following structural formula to a slurry solution followed by measurement of LPD and surface clouding (DWO haze) thereof. Preparation of the slurry composition and silicon wafer polishing conditions are as indicated below.
  • Polishing treatment under the conditions indicated below was applied to a 12-inch p-type silicon wafer having resistivity of 0.1 ⁇ cm to 100 ⁇ cm and crystal orientation of ⁇ 100> using the slurry compositions prepared in 1 above after removing the natural oxide film by rinsing with hydrogen fluoride (0.5%) for 2 minutes at 23°C and using concentrates of the slurry compositions as polishing liquid after diluting 20-fold with water.
  • Polishing apparatus 12-inch single-side polishing machine, Model SPP800S manufactured by Okamoto Machine Tool Works Ltd.
  • Wafer head Template type
  • Polishing pad SPM3100 manufactured by Dow Corp.
  • the silicon wafer was batch-rinsed with SC-1 (solution comprising ammonia (29% by weight aqueous solution), hydrogen peroxide (31% by weight aqueous solution) and pure water at a ratio of 1:1:4 (volume ratio)) for 20 minutes at 23°C, followed by further scrubbing with a PVA brush using the Model SC-200S Brush Scrubber manufactured by Shibaura Mechatronics Corp. with SC-1 (solution comprising ammonia (29% by weight aqueous solution), hydrogen peroxide (31% by weight aqueous solution) and pure water at a ratio of 1:4:20 (volume ratio)) at 23°C, and rinsing with pure water.
  • SC-1 solution comprising ammonia (29% by weight aqueous solution), hydrogen peroxide (31% by weight aqueous solution) and pure water at a ratio of 1:4:20 (volume ratio)
  • the DWO haze value as measured in the dark-field wide channel with oblique incident (DWO) mode using the Surfscan SP2 manufactured by KLA-Tencor Ltd. was used to evaluate surface roughness (haze) of the silicon wafer surface after polishing.
  • LPD values used were similarly determined in the dark-field wide channel with oblique incident (DCO) mode using the Surfscan SP2 manufactured by KLA-Tencor Ltd.
  • Nanoscale polishing defects were defined as the number of signals having intensity that is lower than the intensity of LPD signals and for which scatter intensity from the surface is locally stronger than baseline intensity. More specifically, in the present example, evaluations were made by counting the number of those signals observed in a set region. Each measured value was measured at least twice under the same conditions for the same additive, and relative evaluations of superior (A), good (B), average (C) or poor (E) were made using the average values thereof.
  • a slurry composition and substrate polishing method can be provided that make it possible to simultaneously improve haze, LPD and nanoscale polishing defects.

Abstract

Provided is a slurry composition, a rinse composition, a substrate polishing method and a rinsing method for chemical mechanical polishing. The slurry composition of the present invention is a slurry composition for chemical mechanical polishing comprising water, abrasive grains, and one or more a water-soluble polymer containing a polyvinyl alcohol structural unit. In the case one the water-soluble polymer is present in the slurry composition, a polyoxyalkylene oxide structural unit and polyvinyl alcohol structural unit thereof are able to form a backbone or side chain of the water-soluble polymer. The slurry composition of the present invention can contain a pH adjuster, a water-soluble polymer selected from a cellulose-based polymer and a polyalkylene oxide-based polymer, and a haze improver. The water-soluble polymer can be present in the slurry composition at 1 ppm to 5000 ppm.

Description

SLURRY COMPOSITION, RINSE COMPOSITION, SUBSTRATE POLISHING METHOD AND RINSING METHOD
The present invention relates to a technology for polishing semiconductor substrates, and more particularly, relates to a slurry composition, a rinse composition, a substrate polishing method and a rinsing method used in chemical mechanical polishing (CMP) and the like.
Semiconductor substrates in the form of silicon wafers used in the production of semiconductor devices are used to supply semiconductor devices after being subjected to various types of photolithography, deposition treatment, polishing treatment and the like. Numerous processing steps are applied to silicon wafers in order to fabricate semiconductor devices, and since it also necessary to improve the yield of semiconductor devices, the surface quality of silicon wafers is subject to strict requirements. Chemical mechanical polishing (CMP) has been conventionally used to ensure surface quality by mirror-polishing silicon wafers.
When using CMP to polish silicon wafers, the silicon wafer is typically held on a carrier for immobilizing the silicon wafer, the silicon wafer is then interposed between upper and lower surface plates having abrasive cloths affixed thereto that contain synthetic resin foam or suede-like artificial leather and the like, and the silicon wafer is then polished while being pressed and rotated while supplying an aqueous composition comprising a dispersion of silica, alumina, ceria, zirconia or other colloidal particles (to be subsequently referred to as a slurry composition).
When carrying out CMP on a silicon wafer, since there have been increasingly pressing needs for improvement of productivity and surface quality accompanying increased demand, higher semiconductor device performance levels and higher integration densities in recent years, attempts have been to improve polishing speed, surface roughness, haze (surface clouding), flatness (including roll-off (end face sagging), SFQR and ESFQR) and reduction of scratching.
Technologies for improving surface properties of semiconductor substrates have been proposed in the past, and for example, Japanese Unexamined Patent Publication No. 2014-38906 (PTL 1) describes a polishing composition that comprises a polyvinyl alcohol for the backbone structure for the purpose of inhibiting adherence of particles to the polished surface of a polishing target. Moreover, Japanese Unexamined Patent Publication No. H11-140427 (PTL 2) describes a polishing liquid, containing a linear hydrocarbon-based polymer having a carbon long chain backbone and hydroxy-lower alkylene groups in a side chain thereof, and a polishing method using the same.
Although these technologies are known, accompanying demands for higher levels of semiconductor device integration, device size is being required to be reduced even further, thereby requiring further improvement of the surface status of semiconductor substrates in order to improve the yield and other parameters of integrated circuit products.
Japanese Unexamined Patent Publication No. 2014-38906 Japanese Unexamined Patent Publication No. H11-140427
With the foregoing in view, an object of the present invention is to provide a slurry composition, rinse composition, substrate polishing method and rinsing method that make it possible to improve the surface state of semiconductor substrates.
According to the present invention, a slurry composition for chemical mechanical polishing is provided that comprises
water,
abrasive grains and
one or more water-soluble polymer containing a polyvinyl alcohol structural unit.
In the present invention, the aforementioned water-soluble polymer can be a one or more a water-soluble polymer respectively containing a polyoxyalkylene oxide structural unit or polyvinyl alcohol structural unit. In the case one the aforementioned water-soluble polymer is present in the aforementioned slurry composition, the polyoxyalkylene oxide structural unit or the polyvinyl alcohol structural unit thereof is able to form a backbone or side chain of the water-soluble polymer. Moreover, the water-soluble polymer preferably contains a pH adjuster. In addition, the present invention can contain a water-soluble polymer selected from a cellulose-based polymer and polyalkylene oxide-based polymer. The present invention can also contain a haze improver. In the present invention, the water-soluble polymer is preferably contained at 1 ppm to 5000 ppm.
Moreover, according to a second configuration of the present invention, a rinse composition for a polishing substrate is provided that comprises
water and
one or more water-soluble polymer containing a polyvinyl alcohol structural unit.
In the present invention, the aforementioned water-soluble polymer can be one or more a water-soluble polymer respectively containing a polyalkylene oxide structural unit or polyvinyl alcohol structural unit. Moreover, in the case one the water-soluble polymer is contained in the aforementioned slurry composition, the aforementioned polyalkylene oxide structural unit and polyvinyl alcohol structural unit thereof can form a backbone or side chain of the water-soluble polymer. In addition, the present invention can contain a water-soluble polymer selected from a cellulose-based polymer and polyalkylene oxide-based polymer. The present invention can further contain a haze improver. In addition, the water-soluble polymer is preferably contained at 1 ppm to 5000 ppm.
Moreover, in a third configuration of the present invention, a substrate polishing method is provided that comprises
a step for adhering the previously described slurry composition to a polishing substrate, and
a step for polishing the polishing substrate with a polishing pad using the slurry composition.
In addition, according to a fourth configuration of the present invention, a polishing substrate rinsing method is provided that comprises a step for rinsing a polishing substrate with the previously described rinse composition.
According to the present invention, a slurry composition, rinse composition, substrate polishing method and rinsing method are provided that make it possible to improve microscopic surface irregularities, or in other words, nanoscale polishing defects, referred to as, for example, light point defects (LPD), haze, haze scratches or haze lines and the like.
Although the following provides an explanation of the present invention through an embodiment thereof, the present invention is not limited to the embodiment to be subsequently described. Furthermore, in the present embodiment, nanoscale polishing defects are referred to as nanoscratches. The slurry composition or rinse composition of the present invention comprises one or more water-soluble polymer respectively containing a polyalkylene oxide structural unit and a polyvinyl alcohol structural unit. In a first aspect of the water-soluble polymer of the present embodiment, two different polyoxyalkylene oxide and polyvinyl alcohol water-soluble polymers may be contained and formed in each composition. In a second aspect of the present invention, the polyalkylene structural unit or the polyvinyl alcohol structural unit may be present in each composition in the form of a graft polymer that composes a backbone chain or side chain. In the case the polyvinyl alcohol structural unit in the present invention is present in a backbone chain or side chain, a portion of the hydroxyl groups may be substituted with an acyloxy group. Acyloxy groups having two or more carbon atoms can be preferably used for the acyloxy group, and a (CH3COO-) group is particularly preferable.
The polyoxyalkylene oxide in the polyalkylene oxide structural unit can be polyethylene oxide, polypropylene oxide or an (ethylene oxide-propylene oxide) copolymer, and the copolymer may be a random copolymer or block copolymer. The repeating chain length of the alkylene oxide of the polyalkylene oxide is 1 to 1000, more preferably 2 to 300 and even more preferably about 3 to 200.
In the case the water-soluble polymer of the present embodiment respectively composes an independent water-soluble polymer in the manner of polyalkylene oxide or polyvinyl alcohol, the abundance ratio thereof in terms of mol% is preferably 5:95 to 40:60, and from the viewpoint of improving nanoscale polishing defects, can be within the range of 10:90 to 30:70. In addition, the molecular weight of the polyalkylene oxide and polyvinyl alcohol can be within the range of 1,000 to 10,000,000.
In addition, in the case the polyalkylene oxide and polyvinyl alcohol form a graft polymer in the present embodiment, the molecular weight of the graft polymer can be such that the weight average molecular weight is 5,000 to 500,000, and in consideration of the rheological properties of a solution such as a slurry solution, the weight average molecular weight can be preferably within the range of 10,000 to 300,000 and more preferably within the range of 10,000 to 200,000.
The abundance ratio of the polyalkylene oxide backbone to the polyvinyl alcohol backbone in a graft polymer of the present embodiment in terms of mol% is preferably 5:95 to 40:60, and from the viewpoint of improving nanoscale polishing defects, is preferably within the range of 10:90 to 30:70.
The alkylene oxide backbone of the present embodiment can be ethylene oxide, propylene oxide or can form a chain by random polymerization or block polymerization thereof. Among these, the alkylene oxide is most preferably ethylene oxide.
In the case of adding the previously described water-soluble polymer in the form of a graft polymer, a specific example of the water-soluble polymer may be a water-soluble polymer having the general formula (1) indicated below.
Figure JPOXMLDOC01-appb-C000001
 or
Figure JPOXMLDOC01-appb-I000001
In the aforementioned general formulas (1) and (1'), R represents a hydroxyl group or acyloxy group having two or more carbon atoms, a represents an integer of 1 to 10,000, and M1, M2, N1 and N2 represent a real number of 0 or more (grating rate). In general formula (1), R1 represents a hydrogen atom or acyl group. In addition, R2 and R3 may be the same or different and represent a linear or branched alkyl group having two or more carbon atoms, and b represents an integer of 2 to 10,000. Furthermore, R in the aforementioned general formulas (1) and (1') may have a mixed structure in which both a hydroxyl group and acyloxy group are present, namely, a structure in which an acyloxy group has been saponified to a hydroxyl group.
Specific examples of preferable water-soluble polymers in the present embodiment include water-soluble polymers having the structural formulas (2) and (3) indicated below. Furthermore, a portion or terminal hydroxyl group of the hydroxyl groups of the following general formulas (2) and (3) may be substituted with an acyloxy group.
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000003
In the present embodiment, the aforementioned water-soluble polymer can be present in the slurry composition within a range of 1 ppm (0.001% by weight) to 5000 ppm (0.5% by weight). In addition, the water-soluble polymer is preferably added within the range of 10 ppm to 1000 ppm from the viewpoint of maintaining a polishing speed that enables realistic production throughput.
The slurry composition of the present embodiment can contain a polymer having a tertiary amine structure in the main chain structure thereof for use as a haze improver for improving LPD and haze on a semiconductor substrate surface.
The aforementioned polymer used in the present invention can be produced by addition polymerization of an alkylene oxide at least containing ethylene oxide with an active hydrogen of a polyamine compound having two or more primary amino groups and/or a secondary amino groups and containing 4 to 100 N atoms in a molecule thereof. The weight average molecular weight of the polymer can be within the range of 5,000 to 100,000. In addition, the number of N atoms contained in the polymer of the present embodiment is preferably 2 to 10,000 or less from the viewpoint of providing water solubility in order to apply to a CMP process, and the number of N atoms is preferably within the range of 2 to 1,000 from the viewpoint of providing adequate CMP process compatibility while improving haze. In the following explanation of the present embodiment, this polymer is referred to as an alkylene-polyalkylene oxide amine polymer (APOA).
Examples of polyamine compounds that impart a main chain structure in the present embodiment may include polyethylene polyamines such as triethylene tetraamine, tetraethylene pentamine, pentaethylene hexamine or hexaethylene heptamine, and polyalkylene imines such as polyethylene imine obtained by polymerization of ethylene imine. The aforementioned compounds can be used alone or two or more can be used in combination to form a polyamine main chain structure of the present embodiment.
Examples of alkylene oxides added to the aforementioned main chain structure include ethylene oxide, propylene oxide and butylene oxide, and these alkylene oxides can be used alone or as a mixture of a plurality thereof.
The alkylene oxide backbone able to be used in the present embodiment is preferably selected from an ethylene oxide backbone and/or a polypropylene backbone. The ratio of ethylene oxide in the alkylene oxide added to the polymer of the present embodiment is 5% or more and preferably 10% or more, and by making this ratio of be 50% to 90%, preferable CMP process compatibility can be imparted. In addition, in the case of containing a propylene oxide backbone in the present embodiment, containing within a range of 10% to 20% is similarly preferable in terms of widening the process margin.
The polymer of the present embodiment can be easily produced by an ordinary method. For example, the polymer of the present embodiment can be produced by addition polymerization (graft polymerization) of an alkylene oxide with a starting substance in the form of the aforementioned polyamine compound at a temperature of 100°C to 180°C and atmospheric pressure of 1 atm to 10 atm in the presence of an alkaline catalyst.
There are no particular limitations on the addition mode of the alkylene oxide to the main chain structure in the form of the polyamine compound, and in the case of a mode in which two or more alkylene oxides are added, the addition mode may be in the form of block addition or random addition. The weight average molecular weight of the polymer of the present embodiment can be 5,000 or more and preferably 10,000 or more, and can be made to be within the range of 100,000 or less and 80,000 or less. In the case the weight average molecular weight is excessively low, haze cannot be adequately improved, while in the case weight average molecular weight is excessively high, the dependency of each property on the added amount increases, thereby narrowing the process margin and making this undesirable.
The main chain structure in the present specification refers to a structure containing two or more repeating structural units that contain a tertiary amine that causes graft polymerization of a polyalkylene oxide group. Moreover, the tertiary amine that composes the main chain structure of the present embodiment preferably contains an N-alkylene group. There are no particular limitations on the number of C atoms that compose the N-alkylene group, and a linear or branched alkylene group can be selected that has a number of C atoms within the range of 2 to 10.
A specific example of the polymer of the present embodiment may be exemplified as a polymer represented by the following general formula (4) that is formed by addition polymerization of an alkylene oxide with a polyethylene polyamine, and at least contains a tertiary amine structure in the main chain structure thereof.
Figure JPOXMLDOC01-appb-C000004
In the aforementioned general formula (4), x and y represent positive integers and R4 represents an alkylene group. R3 and R4 represent linear or branched alkylene groups having two or more carbon atoms, and are most preferably ethylene groups from the viewpoints of improving productivity, cost performance and haze. In the present embodiment, x can be within the range of 2 to 1,000 and preferably within the range of 2 to 20, while y can be within the range of 2 to 10,000 and preferably within the range of 2 to 500. If the chain length of the R4O chain is excessively long, the effect of improving surface properties decreases, while if y is 10,000 or more, the dependency of each property on the added amount increases, thereby having a detrimental effect on process margin. R4O can be formed using two or more alkylene oxides, and in the case of the present embodiment, different alkylene oxide groups may be in block form or random form.
The solubility parameter of those compounds given in the aforementioned formulas (1) to (4) in the present invention is preferably made to be within the range of 9 to 16. Furthermore, in the present specification, solubility parameter (SP) refers to the SP value of a water-soluble polymer based on the SP value of the monomer as determined according to the method of Fedors described in Ueda, et al., "Research on Coatings", No. 152, October 2010, pp. 41-46.
Moreover, other water-soluble polymers can be used in combination in the present invention. Examples of such water-soluble polymers may include homopolymers or copolymers formed by polymerizing a vinyl monomer. Examples of such vinyl monomers include water-soluble polymers or copolymers that are homopolymers and arbitrary combinations of copolymers of styrene, chlorostyrene, α-methylstyrene, divinylbenzene; vinyl carboxylates such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl stearate, vinyl adipate, vinyl (meth)acrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate or vinyl cinnamate, acrylonitrile, limonene, cyclohexene; N-vinyl compounds such as 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, N-vinylpyrrolidone, N-vinylacetoamide or N-vinylmethylacetoamide, cyclic ether vinyl compounds such as vinylfuran or 2-vinyloxytetrahydropyran, monovinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, amyl vinyl ether, 2-ethylhexyl vinyl ether, octyl vinyl ether, nonyl vinyl ether, dodecyl vinyl ether, hexadecyl vinyl ether, octadecyl vinyl ether, butoxyethyl vinyl ether, cetyl vinyl ether, phenoxyethyl vinyl ether, allyl vinyl ether, methallyl vinyl ether, glycidyl vinyl ether, 2-chloroethyl vinyl ether or cyclohexyl vinyl ether, ethylene glycol monovinyl ether, polyethylene glycol monovinyl ether, propylene glycol monovinyl ether, polypropylene glycol monovinyl ether, 1,3-butylene glycol monovinyl ether, tetramethylene glycol monovinyl ether, hexamethylene glycol monovinyl ether, neopentyl glycol monovinyl ether, trimethylolpropane monovinyl ether, glycerin monovinyl ether, pentaerythritol monovinyl ether or 1,4-cyclohexanedimethanol monovinyl ether, and the degree of saponification thereof can be suitably adjusted in order to improve water solubility.
In addition to the aforementioned acrylic resins, cellulose derivatives such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose or hydroxypropylmethyl cellulose can be used in the present invention. Cellulose derivatives having an average molecular weight of 50,000 to 2,000,000 can be used.
Specific examples of water-soluble polymers that can be used in combination may include poly-N-vinylpyrrolidone, poly-N-vinylacetoamide, polyglycerin, PEG/PEO having a molecular weight of 1,000 to 1,000,000, PEG-PPG block copolymers, alkylene oxide ethylenediamine adducts (EO weight ratio: 35%, PPG molecular weight: 4400, reverse type), poly-(2-ethyloxazoline) (average molecular weight: 500,000), polyvinyl alcohol (average molecular weight: 200,000), polyacrylic acid (average molecular weight: 25,000) and polyacrylate (average molecular weight: 5,000).
In the case an alkylene-polyalkylene oxide amine polymer is present in the slurry composition of the present invention, the added amount thereof can be within the range of 1 ppm (0.001% by weight) to 5000 ppm (0.5% by weight). In addition, the added amount is preferably within the range of 5 ppm to 1000 ppm from the viewpoint of maintaining a silicon wafer polishing speed that enables realistic production throughput, and is more preferably within the range of 5 ppm to 500 ppm from the viewpoint of not requiring other adjustments of the slurry composition.
In addition to the previously described water-soluble polymer, the slurry composition of the present invention can contain polishing components such as abrasive grain, acid or base, buffer, catalyst or various types of salts. Abrasive grain typically used for polishing can be used for the abrasive grain used in the present invention. Examples of abrasive grain may include metals, metallic or semi-metallic carbides, nitrides, oxides, borides and diamonds.
The abrasive grain able to be used in the present invention is preferably a metal oxide capable of polishing a substrate surface without introducing harmful scratches (marks) or other defects on the substrate surface. Preferable examples of metal oxide abrasive grain may include alumina, silica, titania, ceria, zirconia, magnesia, products co-formed therefrom, mixtures thereof, and chemical mixtures thereof. The abrasive grain is typically selected from the group consisting of alumina, ceria, silica, zirconia and combinations thereof. Silica, and particularly colloidal silica and ceria, are preferable abrasive grains, while colloidal silica is more preferable.
The abrasive grain of the slurry composition of the present invention can be formed in the form of a dispersion or suspension by dispersing the abrasive grain in a preferable liquid carrier and adding various types of additives such as a water-soluble polymer. In many cases, the slurry composition is produced at a higher concentration than the concentration at which it is used for polishing for the purpose of reducing transport cost. In the following description, all locations describing the concentration of the slurry composition refer to the concentration after it has been diluted as a polishing liquid used for polishing. Examples of preferable liquid carriers may include polar solvents, and preferably water or an aqueous solvent, and in the case the abrasive grain is contained in a slurry, the slurry preferably contains the abrasive grain at a concentration at the time of polishing of 0.1% by weight or more and more preferably 0.1% by weight to 50% by weight, and even more preferably, abrasive grain in the form of colloidal silica can be added to the slurry composition at 0.1% by weight to 10% by weight.
The pH of the slurry composition of the present invention can be suitably adjusted in consideration of polishing speed. In the present invention, the pH of the slurry composition is preferably within the range of 5 to 12, and more preferably within the range of 7 to 12 in the case of carrying out polishing treatment on a silicon wafer.
The average particle diameter of primary particles of the abrasive grain is preferably 0.01 μm to 3 μm, more preferably 0.01 μm to 0.8 μm and particularly preferably 0.02 μm to 0.5 μm from the viewpoint of improving polishing speed. Moreover, in the case the primary particles aggregate to form secondary particles, the average particle diameter of the secondary particles can be preferably 0.02 μm to 3 μm, more preferably 0.05 μm to 1 μm and particularly preferably 0.03 μm to 0.15 μm from similar viewpoints of improving polishing speed and reducing surface roughness of the polished object. Furthermore, the average particle diameter of primary particles of the abrasive grain can be determined by observing with a scanning electron microscope or transmission electron microscope, analyzing the resulting images and measuring particle diameter. In addition, the average particle diameter of secondary particles can be measured as volume average particle diameter using the laser light scattering method.
In the present invention, various other additives can be used corresponding to the polishing substrate. Preferable examples of additives that can be present in the polishing system may include amines, ammonium salts, alkaline metal ions, film forming agents, complexing agents, surfactants, rheology control agents, polymeric stabilizers or dispersions and/or halide ions. Additives can be present in the polishing system at an arbitrary preferable concentration.
In addition, an amine compound can be added to the slurry composition, and the amine compound can be selected from aliphatic amines, cyclic amines, heterocyclic amines, aromatic amines, polyamines and combinations thereof. In a preferred embodiment, the amine compound can contain at least one oxygen atom and at least one polar moiety such as an amino acid or amino alcohol, and specific examples thereof may include dimethylpropanol amine, (also known as 2-dimethylamino-2-methyl-1-propanol or DMAMP), 2-amino-2-methyl-1-propanol (AMP), 2-(2-aminoethylamino)ethanol, 2-(isopropylamino)ethanol, 2-(methylamino)ethanol, 2-(diethylamino)ethanol, 2-(2-(dimethylamino)ethoxy)ethanol, 1,1'-[[3-(dimethylamino)propyl]imino]-bis-2-propanol, 2-(butylamino)ethanol, 2-(tert-butylamino)ethanol, 2-(diisopropylamino)ethanol, N-(3-aminopropyl)morpholine and mixtures thereof.
In the present invention, an ammonium salt can be added in addition to an amine compound, and, for example, hydroxylated amines (such as tetramethylammonium hydroxide (TMAH)) and quaternary ammonium compounds can be used.
Alkaline metal ions may also be present in the slurry composition in the form of counter ions of various types of salts. Preferable examples of alkaline metal ions may include monovalent base metals belonging to group 1 of the periodic table. Specific examples of alkaline metal ions that can be used may include sodium ions, potassium ions, rubidium ions and cesium ions. Potassium ions and cesium ions are preferable, while potassium ions are more preferable.
Furthermore, in the present invention, an anticorrosive agent can be used together with the polishing system, and examples of anticorrosive agents may include alkylamines, alkanolamines, hydroxylamines, phosphate esters, sodium lauryl sulfate, fatty acids, polyacrylates, polymethacrylates, polyvinyl phosphonates, polymalates, polystyrene sulfonates, polyvinyl sulfonates, benzotriazole, triazole, benzimidazole and mixtures thereof.
Moreover, in the present invention, a chelating agent and the like can be arbitrarily added to the slurry composition. Examples of chelating agents may include carbonyl compounds such as acetylacetonate, carboxylates such as acetates or aryl carboxylate, carboxylates containing at least one hydroxyl group such as glycolates, lactates, glyconates or gallic acid and salts thereof, dicarboxylates, tricarboxylates and polycarboxylates such as oxalates, phthalates, citrates, succinates, tartrates, malates, edetates such as disodium EDTA, and mixtures thereof. Preferable examples of chelating agents may include dialcohols, trialcohols or polyvalent alcohols such as ethylene glycol, pyrocatechol, pyrogallol or tannic acid, and phosphate-containing compounds.
In the present invention, a surfactant, viscosity modifier or coagulant can be arbitrarily used together with the polishing system. Preferable examples of viscosity modifiers may include urethane polymers and acrylates containing at least one acrylic unit. Specific examples of viscosity modifiers may include low molecular weight carboxylates and high molecular weight polyacrylamide compounds, while preferable examples of surfactants may include cationic surfactants, anionic surfactants, anionic polyelectrolytes, nonionic surfactants, amphoteric surfactants, fluorinated surfactants and mixtures thereof.
A substrate can be polished with a polishing system provided with a suitable polishing pad. A woven or non-woven polishing pad, for example, can be preferably used for the polishing pad. A specific example of a preferable polishing pad that can be used may be a synthetic resin polishing pad, and preferable examples of polymers used may include, for example, polyvinyl chloride, polyvinyl fluoride, nylon, hydrogen fluoride, polycarbonate, polyester, polyacrylate, polyether, polyethylene, polyamide, polyurethane, polystyrene, polypropylene and co-formed products and mixtures thereof.
In addition, the slurry composition and substrate polishing method of the present invention can be applied to not only silicon substrates, but also to substrates to which polishing treatment can be applied, such as silicon substrates, sapphire substrates, SiC substrates, GaAs substrates, GaN substrates or TSV substrates having a polysilicon film, SiO2 film or metal wiring film formed thereon. In addition, the present invention can be applied to not only a method in which the slurry composition is prepared in advance followed by polishing with a polishing pad while supplying the prepared slurry composition to a polishing substrate, but also to a polishing method in which so-called on-platen formulation and preparation are carried out comprising supplying a diluent and undiluted slurry onto a polishing pad and preparing the slurry composition for substrate polishing in the vicinity of the polishing pad.
Moreover, in the present invention, an aqueous solution containing water and a water-soluble polymer represented by general formula (1) can be used as a rinsing solution used to rinse a polishing substrate following polishing treatment. The rinse composition of the present embodiment can be used after adding, in addition to water and the water-soluble polymer represented by general formula (1), various types of additives, excluding abrasive grain, such as a cellulose-based polymer, polyalkylene oxide polymer, other water-soluble polymers or a pH adjuster such as an acid or base.
Although the previous description has provided a detailed explanation of the present invention through an embodiment thereof, the following provides an explanation of the present invention using specific examples. Furthermore, the following examples are indicated for the purpose of facilitating understanding of the present invention and are not intended to limit the present invention in any way.
The slurry composition of the present invention was fabricated by adding an additive having the following structural formula to a slurry solution followed by measurement of LPD and surface clouding (DWO haze) thereof. Preparation of the slurry composition and silicon wafer polishing conditions are as indicated below.
1. Preparation of Slurry Composition (Polishing Liquid Concentrate)
Slurry compositions having the compositions shown in the following Table 1 were respectively prepared by adding an exemplifiable compound of structural formula (2) in the form of a polyvinyl alcohol-polyethylene oxide graft copolymer (80:20 mol%, Mw = 93,600, degree of gelation: 98.5%, main chain: polyvinyl alcohol, side chain: polyethylene oxide), an exemplifiable compound of structural formula (3) in the form of a polyethylene oxide-polyvinyl alcohol graft copolymer (25:75 mol%, Mw = 45,000, degree of gelation: 92% to 99%, main chain: polyethylene oxide, side chain: polyvinyl alcohol), and/or an exemplifiable compound of structural formula (4) in the form of an alkylene-polyalkylene oxide polyamine polymer (EO:PO = 8:2, average number of nitrogen atoms: 5, Mw = 46,000). Furthermore, Examples 1 to 3 are examples of the present invention, while Example 4 is a comparative example.
Figure JPOXMLDOC01-appb-T000001
2. Polishing Conditions
Polishing treatment under the conditions indicated below was applied to a 12-inch p-type silicon wafer having resistivity of 0.1 Ω・cm to 100 Ω・cm and crystal orientation of <100> using the slurry compositions prepared in 1 above after removing the natural oxide film by rinsing with hydrogen fluoride (0.5%) for 2 minutes at 23°C and using concentrates of the slurry compositions as polishing liquid after diluting 20-fold with water.
(1) Polishing apparatus: 12-inch single-side polishing machine, Model SPP800S manufactured by Okamoto Machine Tool Works Ltd.
(2) Wafer head: Template type
(3) Polishing pad: SPM3100 manufactured by Dow Corp.
(4) Surface plate rotating speed: 31 rpm
(5) Polishing pad rotating speed: 33 rpm
(6) Polishing pressure: 3 psi = 210 g/cm2 = 20.7 kPa
(7) Slurry supply rate: 500 mL/min (free flow)
After polishing, the silicon wafer was batch-rinsed with SC-1 (solution comprising ammonia (29% by weight aqueous solution), hydrogen peroxide (31% by weight aqueous solution) and pure water at a ratio of 1:1:4 (volume ratio)) for 20 minutes at 23°C, followed by further scrubbing with a PVA brush using the Model SC-200S Brush Scrubber manufactured by Shibaura Mechatronics Corp. with SC-1 (solution comprising ammonia (29% by weight aqueous solution), hydrogen peroxide (31% by weight aqueous solution) and pure water at a ratio of 1:4:20 (volume ratio)) at 23°C, and rinsing with pure water.
3. Measurement Methods
The DWO haze value as measured in the dark-field wide channel with oblique incident (DWO) mode using the Surfscan SP2 manufactured by KLA-Tencor Ltd. was used to evaluate surface roughness (haze) of the silicon wafer surface after polishing. LPD values used were similarly determined in the dark-field wide channel with oblique incident (DCO) mode using the Surfscan SP2 manufactured by KLA-Tencor Ltd. Nanoscale polishing defects were defined as the number of signals having intensity that is lower than the intensity of LPD signals and for which scatter intensity from the surface is locally stronger than baseline intensity. More specifically, in the present example, evaluations were made by counting the number of those signals observed in a set region. Each measured value was measured at least twice under the same conditions for the same additive, and relative evaluations of superior (A), good (B), average (C) or poor (E) were made using the average values thereof.
4. Results
Evaluation results are shown in the following Table 2.
Figure JPOXMLDOC01-appb-T000002
Moreover, when a rinse composition was produced that did not contain abrasive grains, and the polishing substrates of Examples 1 and 2 were rinsed by brush-scrubbing with the rinse composition following the aforementioned polishing while similarly evaluating LPD, haze (DWO) and nanoscale polishing defects, favorable results were obtained.
As has been described above, according to the present invention, a slurry composition and substrate polishing method can be provided that make it possible to simultaneously improve haze, LPD and nanoscale polishing defects.
Although the previous description has provided an explanation of the present invention using an embodiment thereof, the present invention is not limited to the present embodiment, it can be modified within a range that can be conceived by a person with ordinary skill in the art, such as in the form of other embodiments, additions, alterations or omissions, and any of those aspects are included within the scope of the present invention provided they demonstrate the operation and effects of the present invention.

Claims (15)

  1. A slurry composition for chemical mechanical polishing, comprising:
    water,
    abrasive grains, and
    one or more a water-soluble polymer containing a polyvinyl alcohol structural unit.
  2. The slurry composition according to claim 1, wherein the water-soluble polymer is one or more water-soluble polymer respectively containing a polyoxyalkylene oxide structural unit or polyvinyl alcohol structural unit.
  3. The slurry composition according to claim 1 or 2, wherein, in the case one the water-soluble polymer is present in the slurry composition, the polyoxyalkylene oxide structural unit or the polyvinyl alcohol structural unit thereof forms a backbone or side chain of the water-soluble polymer.
  4. The slurry composition according to any of claims 1 to 3, further comprising a pH adjuster.
  5. The slurry composition according to any of claims 1 to 4, comprising a water-soluble polymer selected from a cellulose-based polymer and a polyalkylene oxide-based polymer.
  6. The slurry composition according to any of claims 1 to 5, further comprising a haze improver.
  7. The slurry composition according to any of claims 1 to 6, comprising 1 ppm to 5000 ppm of the water-soluble polymer.
  8. A rinse composition for a polishing substrate, comprising:
    water, and
    one or more a polyvinyl alcohol structural unit.
  9. The rinse composition according to claim 8, wherein the water-soluble polymer is one or more water-soluble polymer respectively containing a polyoxyalkylene oxide structural unit or polyvinyl alcohol structural unit.
  10. The rinse composition according to claim 8 or 9, wherein, in the case one the water-soluble polymer is present in the rinse composition, the polyoxyalkylene oxide structural unit or the polyvinyl alcohol structural unit thereof forms a backbone or side chain of the water-soluble polymer.
  11. The rinse composition according to any of claims 8 to 10, comprising a water-soluble polymer selected from a cellulose-based polymer and a polyalkylene oxide-based polymer.
  12. The rinse composition according to any of claims 8 to 11, further comprising a haze improver.
  13. The rinse composition according to any of claims 8 to 12, comprising 1 ppm to 5000 ppm of the water-soluble polymer.
  14. A substrate polishing method, comprising:
    a step for adhering the slurry composition according to any of claims 1 to 7 to a polishing substrate, and
    a step for polishing the polishing substrate with a polishing pad using the slurry composition.
  15. A polishing substrate rinsing method, comprising:
    a step for rinsing a polishing substrate with the rinse composition according to any of claims 8 to 13.
PCT/JP2015/004504 2014-09-05 2015-09-04 Slurry composition, rinse composition, substrate polishing method and rinsing method WO2016035346A1 (en)

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