JP5551042B2 - Chemical mechanical polishing method and slurry used therefor - Google Patents

Description

  The present invention relates to a slurry for chemical mechanical polishing (hereinafter sometimes abbreviated as “CMP”) that can be suitably used for manufacturing a semiconductor device, and a chemical mechanical polishing method using the slurry. About. The CMP slurry of the present invention can be suitably used particularly in the step of forming a shallow trench isolation region.

  The high performance of semiconductor circuits has been achieved by miniaturizing transistors, resistors, wirings, etc. constituting the circuits, and achieving high density and high speed response at the same time. In addition, higher wiring density and higher integration became possible by stacking wiring. Semiconductor device manufacturing technologies that enable these include shallow trench isolation, metal plugs, damascene processes, and the like. Shallow trench isolation is one type of element isolation, and CMP is an indispensable technique for the process of forming the shallow trench isolation region. Fine patterns such as shallow trench isolation regions are formed by photolithography, but as the miniaturization progresses, the depth of focus of the projection lens used for photolithography becomes shallower, and the unevenness of the wafer must be within that range. Therefore, the required flatness is increased. By flattening the processed surface by CMP, a flat surface at the nano-order level can be obtained, and high performance can be achieved by three-dimensional wiring, that is, lamination.

  In the process of forming the shallow trench isolation region, CMP is used to remove excess insulating film (such as silicon oxide) formed on the substrate, and a stopper is provided under the insulating film for the purpose of stopping polishing. A membrane is used. In general, silicon nitride is used for the stopper film, and the polishing end point is set by increasing the polishing rate ratio between the insulating film (silicon oxide, etc.) and the stopper film (silicon nitride, etc.). Becomes easier.

Conventionally, a slurry for chemical mechanical polishing containing a water-soluble polymer (polyacrylic acid or the like), β-cyclodextrin, colloidal silica, and water is known (see Patent Document 1). The document describes that the slurry is used to remove the second insulating film (high dielectric constant material such as SiO ₂ ) on the first insulating film (low dielectric constant material such as SiOC). Yes.

  Furthermore, a polishing liquid containing an acid (such as an organic acid having a carboxy group) and an inclusion compound (such as cyclodextrin) is also known (see Patent Document 2). This document describes the use of the polishing liquid for chemical mechanical polishing of a barrier layer and an interlayer insulating film of a semiconductor integrated circuit.

  A polishing composition for polishing a semiconductor device containing water, cerium oxide (abrasive fine particles) and a chelating agent (such as ethylenediaminetetraacetic acid) is also known (see Patent Document 3). This document describes chemical mechanical polishing using the composition in order to planarize a substrate surface having an element isolation structure.

JP 2009-158810 A JP 2009-302255 A International Publication No. WO01 / 080296

The shallow trench isolation region is generally formed through the following processes.
1 to 5 are schematic cross-sectional views showing steps of forming a shallow trench isolation region in a semiconductor device manufacturing process. 1 to 5 show that a part of one semiconductor device is formed in the substrate (wafer) 1, but in reality, a shallow trench isolation region is formed on one substrate. A plurality of semiconductor devices are produced and separated into individual semiconductor devices (chips) by dicing. In addition, the dimensions of each part in the drawing are set for easy understanding, and the dimensional ratio between each part does not necessarily match the actual one.

  First, the stopper film 3 is laminated on the oxide insulating film 2 (such as silicon oxide) on the surface of the substrate 1. Next, a resist film (not shown) is laminated by photolithography on the substrate 1 on which the oxide insulating film 2 and the stopper film 3 are laminated, and after etching, the resist film is removed to form the groove 4 (etched portion). Formed (FIG. 1). An insulating film 5 (silicon oxide or the like) is laminated by CVD or the like so as to fill the groove 4 (FIG. 2). In polishing of the substrate 1 on which the insulating film 5 is laminated by CMP, the stopper film 3 and the insulating film 5 are ideally polished to form a flat shallow trench isolation region 6 (FIG. 3).

  However, since there is a difference in height between the stopper film 3 and the groove 4 (FIG. 1), the insulating film 5 having the initial step D1 is formed by CVD or the like (FIG. 2). Therefore, the subsequent polishing by CMP has a problem that a step D2 (FIG. 4) is formed between the stopper film 3 and the insulating film 5.

  Furthermore, since the substrate has waviness, it is practically difficult to polish uniformly over the entire substrate. Therefore, if the polishing is performed until all the stopper films 3 on the substrate are completely exposed, the insulating film 5 filled in the grooves 4 is further polished in the portion where the stopper film 3 is exposed at an early stage. Problem (excessive polishing) occurs. In this excessively polished portion, the step becomes even larger (FIG. 5). D3 in FIG. 5 is the amount of increase in level difference due to excessive polishing.

  In this regard, in Patent Documents 1 to 3, there is no description or suggestion about reducing the step D2 between the stopper film 3 and the insulating film 5 between the stopper film and the insulating film in CMP. As a result of confirmation by the present inventors, in CMP using the slurry or the like described in the document, the step D2 between the step stopper film 3 and the insulating film 5 between the stopper film and the insulating film is reduced. could not. Patent Documents 1 to 3 do not describe any increase in the level difference due to excessive polishing.

  Accordingly, the present invention provides a CMP slurry (in particular, a step of forming a shallow trench isolation region) that is excellent in the performance of planarizing a film to be polished (hereinafter, sometimes referred to as “planarization performance”). It is an object of the present invention to provide a CMP slurry) in which a step between the insulating film and the insulating film can be made extremely small, and an increase in the step due to excessive polishing can be suppressed.

  As a result of intensive research to solve the above problems, the present inventors have found that a CMP slurry having a specific composition is excellent in flattening performance, and if this is used, the step difference between the stopper film and the insulating film is extremely reduced. The present invention has been completed by finding that it can be made smaller. The present invention is as follows.

[1] A chelating agent (a) having 3 to 8 acidic groups and 4 to 12 atoms between the most distant acidic groups, an oligosaccharide and / or a derivative thereof (b), Containing cerium oxide abrasive grains (c) and water (d),
The content of the chelating agent (a) is 0.02 to 2.0% by mass in the total amount of the slurry,
Content of the said oligosaccharide and / or its derivative (b) is 0.02-2.0 mass% in the slurry whole quantity,
Chemical mechanical polishing slurry.
[2] The slurry for chemical mechanical polishing according to the above [1], wherein a mass ratio of the chelating agent (a) to the oligosaccharide and / or derivative (b) thereof is 1/10 to 10/1. .
[3] The chemical mechanical polishing slurry according to the above [1] or [2], wherein the oligosaccharide and / or derivative (b) thereof is a cyclic oligosaccharide and / or derivative thereof.
[4] The slurry for chemical mechanical polishing according to the above [3], wherein the cyclic oligosaccharide is one or more selected from the group consisting of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin. .
[5] The chelating agent (a) is ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetra (methylenephosphonic acid) (EDTMP), N- (2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA), 1,3-propanediamine. Any one of the above [1] to [4], which is one or more selected from the group consisting of tetraacetic acid (PDTA), diethylenetriaminepentaacetic acid (DTPA), and triethylenetetraminehexaacetic acid (TTHA) The slurry for chemical mechanical polishing described in 1.
[6] The slurry for chemical mechanical polishing according to any one of the above [1] to [5], wherein the pH is 3.0 to 12.5.
[7] A chemical mechanical polishing method using the chemical mechanical polishing slurry according to any one of [1] to [6].
[8] The chemical mechanical polishing method according to the above [7], which is used in the step of forming the shallow trench isolation region.

  If the slurry for CMP of the present invention is used, the step between the stopper film and the insulating film can be made extremely small. Therefore, the CMP slurry of the present invention can be particularly suitably used in the step of forming the shallow trench isolation region.

It is a schematic cross section of the board | substrate which formed the groove | channel by the etching. It is a schematic cross section of the board | substrate which laminated | stacked the insulating film by CVD. It is a schematic cross section of a substrate whose insulating film is polished by ideal CMP. It is a schematic cross section of the board | substrate which polished the insulating film by actual CMP. It is a schematic cross section of the substrate which carried out overpolishing.

  The CMP slurry of the present invention contains a chelating agent (a), an oligosaccharide and / or its derivative (b), cerium oxide abrasive grains (c) and water (d). The CMP slurry of the present invention selectively polishes the convex portion of the film to be polished by using the chelating agent (a), the oligosaccharide and / or its derivative (b) and the cerium oxide abrasive (c) in combination. As a result, the step D2 (FIG. 4) between the stopper film 3 and the insulating film 5 can be reduced.

  Although the reason why the step D2 between the stopper film 3 and the insulating film 5 can be reduced by using the CMP slurry of the present invention is not clear, the chelating agent (a) as an additive, the oligosaccharide and / or its derivative ( The present inventors presume that this is because b) forms a composite and the adsorbability of the additive to the stopper film 3 and the insulating film 5 is improved. More specifically, it is considered that the adsorbed additive functions as a protective film because the pressure applied to the concave portion of the insulating film 5 is low at the initial stage of polishing. Since the applied pressure is high at the convex portion of the insulating film 5, the additive is peeled off, the protective function as described above is not exhibited, and the initial step D 1 is reduced. After that, polishing proceeds, and after the stopper film 3 is exposed, polishing does not proceed in the stopper film 3, and the additive functions as a protective film also in the insulating film 5, and the step increase amount D3 is suppressed. However, the present invention is not limited to such an estimation mechanism.

  Hereinafter, the chelating agent (a), oligosaccharide or derivative thereof (b), cerium oxide abrasive (c) and water (d) used in the present invention will be described in order.

  The chelating agent (a) has 3 or more and 8 or less acidic groups, and the number of atoms between the most distant acidic groups is 4 to 12. A chelating agent (a) may be used individually by 1 type, and may use 2 or more types together. Content of a chelating agent (a) exists in the range of 0.02-2.0 mass% in the slurry whole quantity. If the amount of the chelating agent (a) is less than 0.02% by mass in the total amount of the slurry, the step between the stopper film and the insulating film becomes large, and the amount of increase in the step may become large during excessive polishing. On the other hand, when the content of the chelating agent (a) exceeds 2.0 mass% in the total amount of the slurry, the cerium oxide abrasive grains (c) in the CMP slurry tend to aggregate. From the viewpoint of reducing the level difference between the stopper film and the insulating film, reducing the level difference when overpolishing, and suppressing aggregation of cerium oxide abrasive grains in the abrasive, the content of the chelating agent (a) is the total amount of the slurry. It is preferable that it exists in the range of 0.03-1.0 mass%, and it is more preferable that it exists in the range of 0.04-0.5 mass%.

  The chelating agent (a) has 3 or more and 8 or less acidic groups. When the chelating agent (a) has less than 3 acidic groups, the step between the stopper film and the insulating film cannot be sufficiently suppressed. The reason is presumed that when the number of acidic groups is less than 3, a complex is not sufficiently formed between the chelating agent (a) and the oligosaccharide and / or its derivative (b). In order to sufficiently secure the step-suppressing effect, the chelating agent (a) preferably has 4 or more acidic groups. On the other hand, from the viewpoint of easy availability of the chelating agent (a), the number of acidic groups is more preferably 7 or less, and even more preferably 6 or less.

Examples of the acidic group include a carboxy group (—COOH) and a phosphono group (—P (O) (OH) ₂ ), and a carboxy group is preferable. The acidic group may be in the form of a salt (eg, —COONa) as well as a free acid form. Examples of the cation contained in the salt-form acidic group include alkali metal ions (for example, sodium ions and potassium ions), alkali metal ions (for example, calcium ions), ammonium ions, and the like. In order to avoid metal contamination during the production of a semiconductor device, the acidic group is preferably in the form of a free acid, or in the form of an ammonium salt or an amine salt.

  In the chelating agent (a), it is also necessary that the number of atoms between the most distant acidic groups (for example, a carboxy group or a phosphono group) is 4 to 12. If the number of atoms is less than 4, the step between the stopper film and the insulating film cannot be sufficiently suppressed. On the other hand, it is difficult to obtain a chelating agent (a) having more than 12 atoms. The number of atoms is preferably 4 to 10, more preferably 4 to 8.

  Examples of the chelating agent (a) include ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetra (methylenephosphonic acid) (EDTMP), N- (2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA), and 1,3-propanediaminetetraacetic acid. (PDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), 2-hydroxypropane-1,3-diaminetetraacetic acid (DPTA), glycol ether diamine-N, N, N ′, N′— Examples include tetraacetic acid (GEDTA), (S, S) -ethylenediamine disuccinic acid, L-aspartic acid-N, N-diacetic acid, dicarboxymethyl glutamic acid, and the like. From the viewpoints of reducing the step between the stopper film and the insulating film, reducing the amount of step increase during excessive polishing, industrial availability, etc., ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetra (methylenephosphonic acid) (EDTMP) ), N- (2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA), 1,3-propanediaminetetraacetic acid (PDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), 2-hydroxypropane- 1,3-diaminetetraacetic acid (DPTA) is more preferred, ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetra (methylenephosphonic acid) (EDTMP), N- (2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA), 1,3 -Propanediaminetetraacetic acid (PDTA) Diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA) is more preferred.

  Next, oligosaccharide and / or its derivative (b) will be described. In the present invention, the term “oligosaccharide” refers to a compound in which monosaccharides are bonded at 2 or more and 20 or less regardless of the bonding position.

  The monosaccharide may be either D-form or L-form. Examples of monosaccharides include allose, talose, growth, glucose, altrose, mannose, galactose, idose, rhamnose, erythrose, threose, ribose, lyxose, xylose, arabinose and the like.

  Oligosaccharide and / or its derivative (b) may be used alone or in combination of two or more. Content of oligosaccharide and / or its derivative (b) exists in the range of 0.02-2.0 mass% in the whole slurry quantity. If the oligosaccharide and / or its derivative (b) is less than 0.02% by mass in the total amount of the slurry, the level difference between the stopper film and the insulating film becomes large, and the level difference increase at the time of excessive polishing is increased. growing. On the other hand, when the content of the oligosaccharide and / or its derivative (b) exceeds 2.0% by mass in the total amount of the slurry, the cerium oxide abrasive grains (c) in the CMP slurry aggregate. Oligosaccharides and / or derivatives thereof from the viewpoint of reducing the level difference between the stopper film and the insulating film, reducing the level of increase in level during excessive polishing, and suppressing aggregation of the cerium oxide abrasive grains (c) in the abrasive. The content of (b) is more preferably in the range of 0.03 to 1.0% by mass and more preferably in the range of 0.04 to 0.5% by mass in the total amount of the slurry.

  In order for oligosaccharide and / or its derivative (b) to form a good complex with chelating agent (a) and exhibit a sufficient level difference-suppressing effect, a cyclic oligosaccharide in which oligosaccharide is cyclized and / or A derivative thereof is preferred.

  Examples of the cyclic oligosaccharide include cyclodextrin, cyclomannin, cycloawadolin, isocyclomaltopentaose, isocyclomaltohexaose, cyclic nigerosyl nigerose, and cyclic nigerosyl trisaccharide. From the viewpoint of industrial availability and water solubility, α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are preferred.

As oligosaccharide or cyclic oligosaccharide derivatives,
(A) The hydrogen atom of the hydroxy group of the oligosaccharide or cyclic oligosaccharide has 1 carbon atom such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, etc. Alkoxylated derivatives substituted with -20 linear or branched alkyl groups,
(B) a hydroxy group possessed by an oligosaccharide or a cyclic oligosaccharide and a carboxylic acid (for example, monocarboxylic acid such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid) Acids, oxalic acid, malonic acid, succinic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid and other dicarboxylic acids, tartaric acid, citric acid, And esterified derivatives obtained by reacting with a carboxy group of a hydroxycarboxylic acid such as isocitric acid.

  The mass ratio of the chelating agent (a) to the oligosaccharide and / or derivative (b) (that is, [chelating agent (a)] / [oligosaccharide and / or derivative (b)]) is 1/10 to 10/10. 10/1 is preferable. Even if the mass ratio is smaller than 1/10 or exceeds 10/1, the step suppression effect tends to decrease. From the viewpoint of the step suppression effect, the mass ratio is more preferably 1/7 to 7/1, and further preferably 1/4 to 4/1.

  Next, the cerium oxide abrasive (c) will be described. The average particle size of the cerium oxide abrasive (c) is preferably in the range of 0.5 to 1,000 nm. If the average particle size is less than 0.5 nm, the polishing rate may decrease. On the other hand, if the average particle diameter is larger than 1,000 nm, polishing flaws tend to occur. From the viewpoint of polishing rate and suppression of polishing scratches, the average particle size is more preferably in the range of 1 to 700 nm, and still more preferably in the range of 5 to 500 nm.

  The average particle size of the cerium oxide abrasive grains (c) can be measured using a particle size measuring device “ELSZ-2” manufactured by Otsuka Electronics Co., Ltd. Specifically, the dispersion water of the cerium oxide abrasive grains (c) was measured twice by the dynamic light scattering method at a temperature of 25 ° C. (with a pinhole diameter of 50 μm and a refractive index of water of 25 ° C. 33, setting of viscosity of dispersed water 0.89 cP and relative dielectric constant 78.3), and cumulant analysis, the average particle size and particle size distribution of the cerium oxide abrasive grains (c) can be obtained, respectively.

  It is preferable that content of a cerium oxide abrasive grain (c) exists in the range of 0.1-3.0 mass% in the slurry whole quantity. When this content is less than 0.1% by mass, the polishing rate may be reduced, and when it exceeds 3.0% by mass, the cerium oxide abrasive grains (c) tend to aggregate. From the viewpoint of securing the polishing rate and suppressing aggregation, the content is more preferably in the range of 0.2 to 2.0 mass%, and further preferably in the range of 0.3 to 1.5 mass%. preferable.

  The CMP slurry of the present invention may contain abrasive grains other than the cerium oxide abrasive grains (c) within a range not impairing the effects of the present invention. Examples of the abrasive grains other than the cerium oxide abrasive grains (c) include fumed silica, colloidal silica, alumina, titania, and zirconia.

  The CMP slurry of the present invention can contain a known dispersant as long as the effects of the present invention are not impaired in order to prevent aggregation of the cerium oxide abrasive grains (c).

  Examples of the dispersant include a water-soluble anionic dispersant, a water-soluble nonionic dispersant, a water-soluble cationic dispersant, and a water-soluble amphoteric dispersant. Examples of the water-soluble anionic dispersant include polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polysulfonic acid and salts thereof. Examples of the water-soluble nonionic dispersant include polyvinyl alcohol, polyvinyl butyral, polyethylene glycol, polyvinyl pyrrolidone, polyacrylamide, polymethacrylamide, N-substituted polyacrylamide, N, N-substituted polyacrylamide and the like. Examples of the water-soluble cationic dispersant include polyethyleneimine and polyallylamine salts. Examples of the water-soluble amphoteric dispersant include a polymer obtained by copolymerizing a monomer having a cationic or anionic unsaturated double bond, a betaine having an anion and a cation at each end.

  The dispersant is suitable for stably dispersing the cerium oxide abrasive grains (c) in a dispersion medium such as water.

  The CMP slurry of the present invention may contain an anionic polymer compound, a nonionic polymer compound, a cationic polymer compound, an amphoteric polymer compound, and a polysaccharide as long as the characteristics of the present invention are not impaired. . Examples of the anionic polymer compound include polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, and a salt of polysulfonic acid. Examples of the nonionic polymer compound include polyvinyl alcohol, polyvinyl butyral, polyethylene glycol, polyvinyl pyrrolidone, polyacrylamide, polymethacrylamide, N-substituted polyacrylamide, N, N-substituted polyacrylamide, polyoxyethylene lauryl ether, polyoxy Examples include ethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether. Examples of the cationic polymer compound include salts of polyethyleneimine and polyallylamine. Examples of the amphoteric polymer compound include a copolymer obtained by copolymerizing a monomer having a cationic and an anionic unsaturated double bond. Examples of the polysaccharide include dextran, glycogen, amylose, amylopectin, heparin, and agarose.

  Furthermore, the CMP slurry of the present invention may contain a low molecular weight compound having a molecular weight of 10 to 1,000 as long as the characteristics of the present invention are not impaired. Examples of the low molecular weight compounds include amines such as ethylamine, diethylamine, triethylamine, pyridine, piperazine, imidazole, butylamine, dibutylamine, isopropylamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, and aminoethylethanolamine. Alcohols such as methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol; formic acid, acetic acid, butyric acid, propionic acid, malonic acid, succinic acid, fumaric acid, maleic acid, phthalic acid, salicylic acid, acrylic acid, Carboxylic acids such as methacrylic acid; amino acids such as glycine, alanine, phenylalanine, glutamic acid, aspartic acid, histidine; dioxane, dimethyl ether, dimethyl ether, methyl ethyl ether Ethers; acetone, diethyl ketone and methyl ethyl ketone; hydrogen peroxide, an oxidizing agent such as ammonium persulfate; benzotriazoles, and the like complexing agents such as thiabendazole.

  The CMP slurry of the present invention includes, for example, three solutions each separately storing three aqueous solutions or slurries each containing a chelating agent (a), an oligosaccharide and / or derivative thereof (b), and a cerium oxide abrasive (c). It may be stored as a slurry for CMP of the formula. Further, the slurry containing the cerium oxide abrasive grains (c) and the mixed solution of the chelating agent (a) and the oligosaccharide and / or its derivative (b) are separately stored as a two-component CMP slurry. May be. In addition, the slurry in which the oligosaccharide and / or its derivative (b) and the cerium oxide abrasive (c) are mixed and the aqueous solution of the chelating agent (a) is stored as a two-component CMP slurry. Also good. Moreover, the slurry which mixed the chelating agent (a) and the cerium oxide abrasive grain (c) and the aqueous solution of the oligosaccharide and / or its derivative (b) are stored as a two-component CMP slurry. Also good. Alternatively, it may be stored as a one-component CMP slurry in which the chelating agent (a), oligosaccharide and / or derivative (b), and cerium oxide abrasive (c) are mixed.

  By appropriately adjusting the composition of the aqueous solution or slurry of the two-component or three-component CMP slurry, it is possible to adjust the polishing rate, the step difference suppressing effect, and the like. As a method using a two-component CMP slurry, for example, (1) a mixed aqueous solution of a slurry containing cerium oxide abrasive grains (c), a chelating agent (a), an oligosaccharide and / or a derivative thereof (b) And by feeding these pipes together, mixing these pipes and mixing them immediately before the outlet of the supply pipe, and supplying them onto the polishing pad. (2) Immediately before polishing, cerium oxide abrasive grains (c) Examples thereof include a method of mixing the slurry to be contained with a mixed aqueous solution of the chelating agent (a) and the oligosaccharide and / or derivative (b) thereof. Further, as described above, when mixing the slurry and the aqueous solution of the two-component CMP slurry in the pipe, or when mixing just before polishing, deionized water is added as necessary for the CMP. The polishing characteristics of the slurry can also be adjusted. The above method can be applied to a method using another two-component CMP slurry or a three-component CMP slurry.

  The pH of the CMP slurry of the present invention is preferably in the range of 3.0 to 12.5. When the pH is less than 3.0, the polishing rate may decrease, and when the pH exceeds 12.5, the flatness of the film to be polished tends to decrease. From the viewpoint of the polishing rate and the flatness of the film to be polished, the pH is more preferably in the range of 3.3 to 12.0, and still more preferably in the range of 3.5 to 11.7.

  The pH of the CMP slurry can be measured using a pH meter. Specifically, the pH can be measured by the method described in Examples described later.

  In order to adjust the pH of the slurry for CMP of the present invention, a pH adjuster (acid or base) may be used. When a base is used as the pH adjuster, the base is preferably an organic amine or aqueous ammonia in order to prevent metal contamination in semiconductor device manufacture.

  The CMP slurry of the present invention contains water (d). Water (d) is a dispersion medium for the slurry for CMP, and deionized water is preferable, distilled water is more preferable, and ultrapure water is more preferable in order to prevent contamination in semiconductor device manufacture. The content of water (d) is an essential component from the slurry for CMP (chelating agent (a), oligosaccharide and / or derivative thereof (b), cerium oxide abrasive (c)) and optional component (for example, dispersing agent). This is the remaining amount excluding the content of.

  The CMP slurry of the present invention can be used in various semiconductor devices, manufacturing processes for MEMS, and the like. For example, an insulating film such as a silicon oxide film or glass formed on a wiring board having a predetermined wiring; a film mainly containing polysilicon, Al, Cu, Ti, TiN, W, Ta, TaN or the like; a photomask lens Optical glass such as prism; Inorganic conductive film such as ITO; Optical integrated circuit composed of glass and crystalline material; Optical switching element; Optical waveguide; End face of optical fiber; Single crystal for optical such as scintillator; Solid laser single crystal Sapphire substrate for blue laser LED; semiconductor single crystal such as SiC, GaP and GaAs; glass substrate for magnetic disk; magnetic head and the like; synthetic resin such as methacrylic resin and polycarbonate resin; In particular, the CMP slurry of the present invention is preferably used for CMP in the step of forming the shallow trench isolation region.

  The present invention also provides a CMP method. The CMP method of the present invention is characterized by using the above-described CMP slurry of the present invention. The CMP method of the present invention is preferably used in a step of forming a shallow trench isolation region.

  A substrate on which a film to be polished is pressed against a polishing pad fixed on a polishing surface plate, and while the slurry for CMP of the present invention is supplied between the substrate and the polishing pad, the substrate and the polishing pad are relatively One embodiment of the present invention is a CMP method that moves and polishes a film to be polished on a substrate. Hereinafter, for illustrative purposes, one embodiment of the present invention will be described using a substrate (FIG. 2) in which an insulating film 5 (such as silicon oxide) is stacked over a stopper film 3 (such as silicon nitride).

  In the CMP method of the present invention, a general polishing apparatus can be used. A general polishing apparatus usually holds a polishing pad, a polishing surface plate for fixing the polishing pad, a motor for rotating the polishing surface plate, a controller for adjusting the rotation speed of the motor, and a substrate. And a holder. The polishing pad is fixed to the polishing surface plate using, for example, a double-sided tape.

  There is no restriction | limiting in particular as a polishing pad, For example, a general synthetic resin, a nonwoven fabric, a woven fabric, artificial leather etc. can be used.

  Examples of the synthetic resin include thermosetting polyurethane resins, thermoplastic polyurethane resins, epoxy resins, fluororesins, polyethylene resins, polyolefin resins such as polypropylene resins, cross-linked rubbers such as polybutadiene resins, polyacrylic resins, polymethacrylic resins, poly Examples include methyl methacrylate resin, polyvinyl alcohol resin, polyvinyl butyral resin, and ethylene-vinyl acetate copolymer resin. The said synthetic resin may be used individually by 1 type, and may use 2 or more types together. Furthermore, the synthetic resin can be used in combination with an additive or the like. From the viewpoint of wear resistance, a polyurethane resin is preferred.

  The synthetic resin may have a foam structure. Examples of the method for producing a synthetic resin having a foam structure include (1) a method of dispersing a minute hollow body in a synthetic resin; (2) dispersing one or more water-soluble polymer compounds in the synthetic resin. Thereafter, a method of eluting the water-soluble polymer compound; (3) a method using supercritical foaming; and (4) a method of sintering polymer compound fine particles to form a communicating hole structure.

  The polishing pad may contain abrasive grains in the polishing pad.

  It is preferable that the polishing pad is subjected to hole processing and / or groove processing so that a slurry for CMP is accumulated. Although not particularly limited, examples of the groove structure include a lattice shape, a radial shape, a spiral shape, and a concentric shape. There may be only one kind of groove structure and hole structure, or two or more kinds. The polishing pad may have a single layer structure or a laminated structure having a cushion layer or the like.

  A conditioner may be used to adjust the surface roughness of the polishing pad to a range suitable for polishing the film to be polished. Examples of the conditioner include those in which diamond particles are fixed on the support surface by nickel electrodeposition or the like. Examples of the method for adjusting the surface roughness include a method of attaching the conditioner to a polishing apparatus and pressing the conditioner on the polishing pad.

  There are no particular limitations on the polishing conditions. However, in order to polish efficiently, the rotation speed of each of the polishing platen and the substrate is preferably 300 rpm or less, and the pressure applied to the substrate is preferably 150 kPa or less so as not to cause scratches after polishing. During polishing, it is preferable to continuously supply the CMP slurry to the polishing pad with a pump or the like. Although the supply amount is not limited, it is preferable that the surface of the polishing layer is always covered with the slurry for CMP.

  The substrate after polishing is preferably washed well with running water and then dried using a spin dryer or the like. Thus, by polishing with the CMP slurry of the present invention, a flat shallow trench isolation region 6 in which the step D2 between the stopper film 3 and the insulating film 5 is suppressed can be formed, and the entire surface of the substrate can be formed. A smooth surface can be obtained. A tungsten wiring, a copper wiring, and the like are further formed on the substrate. By repeating such steps, a semiconductor device having a stacked structure can be manufactured.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by these Examples.

(1) pH measurement of slurry for CMP Standard buffer (phthalate pH buffer: pH 4.00 (25 ° C.), neutral phosphate pH buffer: pH 7.00 (25 ° C.), borate pH buffer Liquid: pH 9.00 (25 ° C.)), calibrating the pH meter (“pH meter F22” manufactured by Horiba, Ltd.) at three points, and then putting the electrode of the pH meter into the slurry for CMP for 2 minutes After the pH value was stabilized after the above, the value was measured.

(2) Preparation of slurry for CMP [Example 1]
1. Slurry of cerium oxide abrasive (Showa Denko Co., Ltd. abrasive “GPL-C1010”, cerium oxide abrasive content in slurry: 10 mass%) 50 g, ethylenediaminetetraacetic acid (EDTA) (manufactured by Kyrest Co., Ltd.) 0 g, 2.0 g of α-cyclodextrin (manufactured by Nippon Food Processing Co., Ltd.) and distilled water were mixed in a 1 L graduated cylinder and stirred with a magnetic stirrer. Co.) or 0.1M hydrochloric acid (Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 5.0, and the total amount was adjusted to 1,000 g with distilled water, and the cerium oxide abrasive content was 0.5 mass. %, A slurry for CMP having an EDTA content of 0.1% by mass and an α-cyclodextrin content of 0.2% by mass was obtained.

[Example 2]
A slurry for CMP was prepared in the same manner as in Example 1 except that the EDTA content was 0.05% by mass.

[Example 3]
A slurry for CMP was prepared in the same manner as in Example 1 except that the α-cyclodextrin content was 0.3% by mass.

[Example 4]
A slurry for CMP was prepared in the same manner as in Example 1 except that the α-cyclodextrin content was 0.1% by mass.

[Example 5]
A slurry for CMP was prepared in the same manner as in Example 1 except that γ-cyclodextrin (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of α-cyclodextrin (containing γ-cyclodextrin in the total amount of the slurry) Amount 0.2% by weight).

[Example 6]
A slurry for CMP was prepared in the same manner as in Example 1 except that trehalose (manufactured by Hayashibara Biochemical Laboratories) was used instead of α-cyclodextrin (the content of trehalose in the total amount of slurry was 0.3). mass%).

[Example 7]
A slurry for CMP was prepared in the same manner as in Example 1 except that ethylenediaminetetra (methylenephosphonic acid) (EDTMP) (manufactured by Kirest Co., Ltd.) was used instead of EDTA.

[Example 8]
A slurry for CMP was prepared in the same manner as in Example 1 except that N- (2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA) (manufactured by Dojindo Laboratories) was used instead of EDTA.

[Example 9]
A slurry for CMP was prepared in the same manner as in Example 1 except that 1,3-propanediaminetetraacetic acid (PDTA) (manufactured by Kirest Co., Ltd.) was used instead of EDTA (content of PDTA in the total amount of slurry) 0.12% by mass).

[Example 10]
A slurry for CMP was prepared in the same manner as in Example 1 except that diethylenetriaminepentaacetic acid (DTPA) (manufactured by Dojindo Laboratories) was used instead of EDTA (the content of DTPA in the total amount of slurry was 0.00). 15% by mass).

[Example 11]
A slurry for CMP was prepared in the same manner as in Example 1 except that triethylenetetramine hexaacetic acid (TTHA) (manufactured by Dojindo Laboratories) was used instead of EDTA (content of TTHA in the total amount of slurry) 0.17% by mass).

[Comparative Example 1]
50 g of cerium oxide abrasive grains, 1.0 g of EDTA, and distilled water were mixed in a 1 L graduated cylinder, and while stirring with a magnetic stirrer, hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 5.0. Thereafter, the total amount was made 1,000 g with distilled water to obtain a slurry for CMP having a cerium oxide abrasive content of 0.5 mass% and an EDTA content of 0.1 mass%.

[Comparative Example 2]
50 g of cerium oxide abrasive grains, 2.0 g of α-cyclodextrin, and distilled water were mixed in a 1 L graduated cylinder, hydrochloric acid was added to pH 8.0 while stirring with a magnetic stirrer, and then with distilled water. The total amount was 1,000 g to obtain a slurry for CMP having a cerium oxide abrasive content of 0.5% by mass and an α-cyclodextrin content of 0.2% by mass.

[Comparative Example 3]
A slurry for CMP was prepared in the same manner as in Example 1 except that the EDTA content was 0.01% by mass and the α-cyclodextrin content was 0.3% by mass.

[Comparative Example 4]
A slurry for CMP was prepared in the same manner as in Example 1 except that the α-cyclodextrin content was 0.005% by mass.

[Comparative Example 5]
A slurry for CMP was prepared in the same manner as in Example 1 except that the α-cyclodextrin content was 3.0% by mass.

[Comparative Example 6]
A slurry for CMP was prepared in the same manner as in Example 1 except that the EDTA content was 3.0% by mass and the α-cyclodextrin content was 0.1% by mass.

[Comparative Example 7]
50 g of cerium oxide abrasive grains, 1.0 g of succinic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 2.0 g of α-cyclodextrin, and distilled water are mixed in a 1 L graduated cylinder, and hydrochloric acid is added while stirring with a magnetic stirrer. In addition, after adjusting the pH to 5.0, the total amount was adjusted to 1,000 g with distilled water, the succinic acid content was 0.1 mass%, the cerium oxide abrasive content was 0.5 mass%, and the α-cyclodextrin content was 0 A 2% by weight slurry for CMP was obtained.

[Comparative Example 8]
CMP was carried out in the same manner as in Example 1 except that fumed silica abrasive “Semi-Sperse 25” (manufactured by Cabot Microelectronics) was used instead of cerium oxide abrasive and the pH of the slurry was 6.5. Slurry was prepared (the content of fumed silica abrasive grains in the total amount of the slurry was 5% by mass).

[Comparative Example 9]
A slurry for CMP was prepared in the same manner as in Example 1 except that nitrilotriacetic acid (NTA) (manufactured by Dojindo Laboratories Co., Ltd.) was used instead of EDTA (NTA content 0.1% in the total amount of slurry) mass%).

(Insulation film polishing test)
A SKW pattern wafer “SKW3-2” was used as a test substrate. As shown in FIG. 2, the wafer is formed with an oxide insulating film 2 (silicon oxide), a stopper film 3 (silicon nitride), a groove 4 and an insulating film 5 (silicon oxide) (oxide insulating film 2). Thickness: 10 nm, thickness of stopper film 3: 150 nm, width of stopper film 3: 100 μm, depth of groove 4 (distance from the surface of stopper film 3 to the bottom of groove 4): 500 nm, width of groove 4 : 100 μm, average thickness of insulating film 5: 600 nm). The wafer was fixed to a substrate holding portion of a polishing apparatus (“BC-15” manufactured by MAT). On the other hand, a non-foamed polyurethane polishing pad with a diameter of 380 mm was attached to the polishing surface plate with a double-sided tape. Using a conditioner (made by Allied Material Co., Ltd., diameter: 19.0 cm), rotating in the same direction at a pressure of 3.48 kPa, a platen rotation speed of 100 rpm, and a conditioner rotation speed of 140 rpm, pure water is metered in by a liquid feed pump (Tokyo Science Instruments). The polishing pad was conditioned for 60 minutes while being supplied at 150 mL / min. The wafer was polished while supplying the CMP slurry prepared as described above onto the polishing pad at 120 mL / min (a polishing platen rotating speed of 100 rpm, a wafer rotating speed of 99 rpm, and a load on the wafer of 23). .4 kPa). When the insulating film 5 (silicon oxide) on the stopper film 3 (silicon nitride) disappeared and the stopper film 3 was exposed, the polishing was finished as just polishing, and the wafer was washed with distilled water and dried. The level difference D2 (FIG. 4) between the stopper film 3 and the insulating film 5 after just polishing was measured using a surface roughness measuring machine. Specifically, using a surface roughness measuring machine (small surface roughness measuring machine “SJ-400” manufactured by Mitutoyo Corporation), standard stylus, measurement range: 80 μm, JIS2001, GAUSS filter, cutoff value λc: 2.5 mm, The wafer after just polishing was measured with a cutoff value λs: 8.0 μm, and the step D2 was calculated from the cross-sectional curve. The results are shown in Tables 1 to 4 below.

  The just-polished wafer was further excessively polished as shown in FIG. 5, and the step height increase D3 was measured. Specifically, the wafer after just polishing is further polished for a time corresponding to 15% of the polishing time from the start of polishing to just polishing, and the step increase amount D3 (FIG. 5) is calculated in the same manner as in the case of the step D2. . The results are shown in Tables 1 to 4 below.

  As is clear from the results of Examples 1 to 11 and Comparative Examples 1 to 9 shown in Tables 1 to 4 above, if the CMP slurry of the present invention is used, the level difference after just polishing and the level difference increase after excessive polishing can be increased. Efficient polishing is possible while suppressing.

1 Substrate 2 Oxide insulating film (silicon oxide, etc.)
3 Stopper film (silicon nitride, etc.)
4 Groove (etched part)
5 Insulating film (silicon oxide, etc.)
6 Shallow trench isolation region D1 Initial step D2 Step D3 Step increment

Claims (5)

Chelating agent (a), oligosaccharide and / or derivative (b) having 3 to 8 acidic groups and 4 to 12 atoms between the most distant acidic groups, cerium oxide abrasive Containing grains (c) as well as water (d),
The content of the chelating agent (a) is 0.02 to 2.0% by mass in the total amount of the slurry,
The content of oligosaccharides and / or derivatives thereof (b) is, in the slurry total amount Ri 0.02 to 2.0% by mass,
The oligosaccharide is one or more selected from the group consisting of α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin;
Ru is used in the step of forming a shallow trench isolation region,
Chemical mechanical polishing slurry.   The slurry for chemical mechanical polishing according to claim 1, wherein a mass ratio of the chelating agent (a) to the oligosaccharide and / or derivative (b) thereof is 1/10 to 10/1. The chelating agent (a) is ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetra (methylenephosphonic acid) (EDTMP), N- (2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA), 1,3-propanediaminetetraacetic acid ( The slurry for chemical mechanical polishing according to claim 1 or 2 , which is one or more selected from the group consisting of PDTA), diethylenetriaminepentaacetic acid (DTPA), and triethylenetetraminehexaacetic acid (TTHA). The slurry for chemical mechanical polishing according to any one of claims 1 to 3 , which has a pH of 3.0 to 12.5. A chemical mechanical polishing method using the slurry for chemical mechanical polishing according to any one of claims 1 to 4 in a step of forming a shallow trench isolation region .

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