JP2017149798A - Polishing liquid, polishing liquid set and method for polishing substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing liquid capable of improving the polishing selectivity of an insulation material for a stopper material.SOLUTION: There is provided a polishing liquid which contains a liquid medium, abrasive grains, a peptide compound having a phenylalanine skeleton and a polymer, wherein the polymer has a first molecular chain to which a functional group is directly bonded and a second molecular chain branched from the first molecular chain and the functional group is at least one selected from the group consisting of a carboxyl group, a carboxylate group, a hydroxyl group, a sulfo group and a sulfonate group.SELECTED DRAWING: None

Description

  The present invention relates to a polishing liquid, a polishing liquid set, and a method for polishing a substrate. In particular, the present invention relates to a polishing liquid, a polishing liquid set, and a substrate polishing method that can be used in a planarization process of a substrate surface, which is a technique for manufacturing a semiconductor element. More specifically, the present invention can be used in a planarization process of shallow trench isolation (shallow trench isolation, hereinafter referred to as “STI” in some cases) insulating material, premetal insulating material, interlayer insulating material, and the like. The present invention relates to a polishing liquid, a polishing liquid set, and a method for polishing a substrate.

  In recent semiconductor device manufacturing processes, the importance of processing technology for higher density and miniaturization is increasing. CMP (Chemical Mechanical Polishing), which is one of the processing techniques, is used to form STI, planarize premetal insulating material or interlayer insulating material, plug or embedded metal wiring in the manufacturing process of semiconductor devices. This technology is essential for formation.

  The most frequently used polishing liquid is a silica-based polishing liquid containing silica (silicon oxide) particles such as fumed silica and colloidal silica as abrasive grains. Silica-based polishing liquid is characterized by high versatility, and it can polish a wide variety of materials regardless of insulating materials and conductive materials by appropriately selecting the abrasive content, pH, type of additives, etc. it can.

  On the other hand, the demand for polishing liquids mainly containing insulating materials such as silicon oxide and containing cerium compound particles as abrasive grains is also expanding. For example, a cerium oxide-based polishing liquid containing cerium oxide (ceria) particles as abrasive grains can polish silicon oxide at high speed even with a lower abrasive grain content than a silica-based polishing liquid (see, for example, Patent Documents 1 and 2 below). .

  By the way, in recent years, in the manufacturing process of a semiconductor element, it has been required to achieve further miniaturization of wiring, and polishing scratches generated during polishing have become a problem. That is, even if a fine polishing flaw occurs when polishing using a conventional cerium oxide-based polishing liquid, there is no problem if the size of the polishing flaw is smaller than the conventional wiring width. However, when trying to achieve further miniaturization of the wiring, there is a problem even if the polishing scratches are minute.

  For this problem, polishing liquids using hydroxide particles of tetravalent metal elements have been studied (for example, see Patent Documents 3 to 5 below). Further, a method for producing hydroxide particles of a tetravalent metal element has been studied (for example, see Patent Documents 6 and 7 below). These techniques try to reduce polishing scratches caused by particles by making the mechanical action as small as possible while taking advantage of the chemical action of the hydroxide particles of the tetravalent metal element.

  Further, in a CMP process or the like for forming the STI, a stopper (a polishing stop layer including a stopper material) disposed on the convex portion of the substrate having the concavo-convex pattern, and the substrate and the stopper so as to fill the concave portion of the concavo-convex pattern. A laminated body having an insulating material (e.g., silicon oxide) disposed on the substrate is polished. In such polishing, the polishing of the insulating material is stopped by a stopper. That is, the polishing of the insulating material is stopped when the stopper is exposed. This is because it is difficult to artificially control the amount of polishing of the insulating material (the amount of removal of the insulating material), and the degree of polishing is controlled by polishing the insulating material until the stopper is exposed. In this case, it is necessary to increase the polishing selectivity of the insulating material with respect to the stopper material (polishing speed ratio: polishing speed of the insulating material / polishing speed of the stopper material). In response to this problem, the following Patent Document 8 uses a polishing liquid containing hydroxide particles of a tetravalent metal element and at least one of a cationic polymer and a polysaccharide, and using silicon nitride as a stopper material. Used to polish an insulating material. Further, Patent Document 9 below discloses an insulating material using a polishing liquid containing hydroxide particles of a tetravalent metal element and polyvinyl alcohol having a saponification degree of 95 mol% or less, and using polysilicon as a stopper material. Polishing is disclosed.

Japanese Patent Laid-Open No. 10-106994 Japanese Patent Application Laid-Open No. 08-022970 International Publication No. 2002/067309 International Publication No. 2012/070541 International Publication No. 2012/070542 JP 2006-249129 A International Publication No. 2012/070544 International Publication No. 2009/131133 International Publication No. 2010/143579

  By the way, in recent years, in the CMP process or the like for forming the STI, the polishing selectivity of the insulating material with respect to the stopper material is increased for the purpose of improving flatness and suppressing erosion (overpolishing of the stopper material). There is a need to increase it further.

  The present invention is intended to solve the above-described problems, and an object of the present invention is to provide a polishing liquid, a polishing liquid set, and a substrate polishing method capable of improving the polishing selectivity of an insulating material with respect to a stopper material. .

  The present inventors have found that by using a peptide compound having a phenylalanine skeleton in combination with a specific polymer, an effect of further increasing the polishing selectivity of the insulating material with respect to the stopper material can be obtained.

  The polishing liquid according to the present invention contains a liquid medium, abrasive grains, a peptide compound having a phenylalanine skeleton, and a polymer, and the polymer includes a first molecular chain having a functional group directly bonded thereto, A second molecular chain branched from one molecular chain, and the functional group is at least one selected from the group consisting of a carboxyl group, a carboxylate group, a hydroxyl group, a sulfo group, and a sulfonate group .

  According to the polishing liquid of the present invention, the polishing selectivity of the insulating material with respect to the stopper material (insulating material polishing rate / stopper material polishing rate) can be improved. Further, according to the polishing liquid according to the present invention, when a peptide compound having a phenylalanine skeleton and the polymer are used in combination, an insulating material of a substrate having a concavo-convex pattern is polished using a stopper. It is possible to suppress the polishing speed of the convex stopper material, and it is possible to polish a substrate having an uneven pattern with good flatness. According to the polishing liquid of the present invention, it is possible to polish an insulating material (for example, silicon oxide) at a high polishing rate and sufficiently suppress the polishing rate of a stopper material (for example, silicon nitride and polysilicon). According to the polishing liquid of the present invention, these insulating materials can be highly planarized in the CMP technique for planarizing the shallow trench isolation insulating material, the premetal insulating material, the interlayer insulating material, and the like. According to the polishing liquid of the present invention, the insulating material can be polished with low polishing scratches while the insulating material is highly planarized.

  By the way, in the conventional polishing liquid using silica particles, ceria particles, etc. as abrasive grains, anionic polymers (polycarboxylic acid, polysulfonic acid, etc.) are used to suppress the polishing rate of the stopper material while increasing the polishing rate of the insulating material. ) Is widely used. However, when the anionic polymer is used in a polishing liquid using hydroxide particles of tetravalent metal elements, the effect of suppressing the occurrence of polishing flaws due to the aggregation of the particles and the polishing of the insulating material The effect of increasing the speed may not be obtained. On the other hand, according to the polishing liquid of the present invention, the insulating material can be polished at a high polishing rate while suppressing the aggregation of abrasive grains (while maintaining dispersion stability), and the polishing rate of the stopper material can be sufficiently suppressed. be able to.

  The first molecular chain includes a structural unit derived from styrene, a structural unit derived from olefin, a structural unit derived from acrylic acid, a structural unit derived from methacrylic acid, a structural unit derived from maleic acid, and a structural unit derived from vinyl acetate. It is preferable to include at least one selected from the group consisting of: As a result, the insulating material can be easily polished at a high polishing rate, and the polishing rate of the stopper material can be sufficiently suppressed.

  The first molecular chain preferably includes at least one selected from the group consisting of a polyester chain, a polyurethane chain, and a polyamide chain. As a result, the insulating material can be easily polished at a high polishing rate, and the polishing rate of the stopper material can be sufficiently suppressed.

  The second molecular chain preferably includes at least one selected from the group consisting of a hydrophilic molecular chain and a hydrophobic molecular chain. This makes it easy to polish the insulating material at a high polishing rate while suppressing the aggregation of abrasive grains, and sufficiently suppresses the polishing rate of the stopper material.

  The second molecular chain preferably includes at least one selected from the group consisting of a polyether chain, a polyvinyl alcohol chain, and a polyvinylpyrrolidone chain. This makes it easy to polish the insulating material at a high polishing rate while suppressing the aggregation of abrasive grains, and sufficiently suppresses the polishing rate of the stopper material.

  The second molecular chain includes a structural unit derived from styrene, a structural unit derived from olefin, a structural unit derived from acrylic acid, a structural unit derived from methacrylic acid, a structural unit derived from maleic acid, a structural unit derived from vinyl acetate, and a polyester chain. It is preferable to contain at least one selected from the group consisting of a polyurethane chain and a polyamide chain. This makes it easy to polish the insulating material at a high polishing rate while suppressing the aggregation of abrasive grains, and sufficiently suppresses the polishing rate of the stopper material.

  The abrasive preferably contains at least one selected from the group consisting of ceria, silica, alumina, zirconia, yttria, and a hydroxide of a tetravalent metal element, and preferably contains a hydroxide of a tetravalent metal element. More preferred. Thereby, the insulating material can be polished at a higher polishing rate.

  The tetravalent metal element hydroxide is preferably at least one selected from the group consisting of rare earth metal hydroxides and zirconium hydroxides. Thereby, generation | occurrence | production of the grinding | polishing damage | wound in a to-be-polished surface can further be suppressed, grind | polishing an insulating material at a still higher grinding | polishing rate.

  The content of the polymer is preferably 0.001% by mass or more and 0.5% by mass or less based on the total mass of the polishing liquid. This makes it easy to polish the insulating material at a high polishing rate while suppressing the aggregation of abrasive grains, and to easily suppress the polishing rate of the stopper material. Moreover, it is possible to further suppress the occurrence of polishing scratches on the surface to be polished.

  Another aspect of the present invention relates to the use of the polishing liquid for polishing a surface to be polished containing silicon oxide. That is, the polishing liquid according to the present invention is preferably used for polishing a surface to be polished containing silicon oxide.

  In the polishing liquid set according to the present invention, the constituents of the polishing liquid are stored separately as a first liquid and a second liquid, and the first liquid includes the abrasive grains and a liquid medium, Two liquids contain the peptide compound, the polymer and a liquid medium. According to the polishing liquid set concerning the present invention, the same effect as the polishing liquid concerning the present invention can be acquired.

  The substrate polishing method according to one aspect of the present invention may include a step of polishing a surface to be polished of the substrate using the polishing liquid, and the first liquid and the second liquid in the polishing liquid set. You may provide the process of grind | polishing the to-be-polished surface of a base | substrate using the polishing liquid obtained by mixing with a liquid. According to these polishing methods, the same effect as the polishing liquid according to the present invention can be obtained by using the polishing liquid or the polishing liquid set.

  Further, a method for polishing a substrate according to another aspect of the present invention is a method for polishing a substrate having an insulating material and silicon nitride, wherein the insulating material is selectively polished with respect to silicon nitride using the polishing liquid. A step of selectively polishing the insulating material with respect to silicon nitride using a polishing liquid obtained by mixing the first liquid and the second liquid in the polishing liquid set May be provided. According to these polishing methods, by using the polishing liquid or the polishing liquid set, the same effect as the polishing liquid according to the present invention is obtained when the insulating material is selectively polished with respect to silicon nitride. be able to.

  A substrate polishing method according to another aspect of the present invention is a method for polishing a substrate having an insulating material and polysilicon, and the insulating material is selectively polished with respect to polysilicon using the polishing liquid. A step of selectively polishing the insulating material with respect to polysilicon using a polishing liquid obtained by mixing the first liquid and the second liquid in the polishing liquid set. It may be. According to these polishing methods, by using the polishing liquid or the polishing liquid set, the same effect as the polishing liquid according to the present invention can be obtained when the insulating material is selectively polished with respect to polysilicon. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, the polishing liquid which can improve the polish selectivity (polishing speed of an insulating material / polishing speed of a stopper material) of the insulating material with respect to a stopper material can be provided. Moreover, according to this invention, the polishing liquid set for obtaining the said polishing liquid can be provided. Furthermore, according to this invention, the grinding | polishing method of the base | substrate using the said polishing liquid or polishing liquid set can be provided. According to the present invention, when polishing an insulating material of a substrate having a concavo-convex pattern using a stopper, it is possible to suppress the polishing rate of the stopper material of the convex portion of the concavo-convex pattern. Polishes with good flatness. According to the present invention, the insulating material (for example, silicon oxide) can be polished at a high polishing rate, and the polishing rate for the stopper material (for example, silicon nitride and polysilicon) can be sufficiently suppressed.

  According to the present invention, polishing can be sufficiently stopped on the stopper regardless of whether silicon nitride or polysilicon is used as the stopper material. In particular, when silicon nitride is used as the stopper material, the insulating material can be polished at a high polishing rate, and the polishing rate of silicon nitride can be sufficiently suppressed. According to the present invention, in the polishing of the insulating material using silicon nitride as the stopper material, when the stopper is exposed, the stopper and the insulating material embedded in the recess are excessively polished. Can be suppressed.

  Furthermore, according to the present invention, these insulating materials can be highly planarized in the CMP technique for planarizing the shallow trench isolation insulating material, the premetal insulating material, the interlayer insulating material, and the like. In addition, according to the present invention, the insulating material can be polished with low polishing scratches while the insulating material is highly planarized.

  ADVANTAGE OF THE INVENTION According to this invention, use of the polishing liquid or polishing liquid set for the planarization process of a base surface can be provided. ADVANTAGE OF THE INVENTION According to this invention, use of the polishing liquid or polishing liquid set for the planarization process of a shallow trench isolation | separation insulating material, a premetal insulating material, or an interlayer insulating material can be provided. ADVANTAGE OF THE INVENTION According to this invention, use of the polishing liquid or polishing liquid set for the grinding | polishing process which grind | polishes an insulating material selectively with respect to a stopper material can be provided.

It is a schematic diagram which shows a mode that an abrasive grain aggregates when an additive is added. It is a schematic diagram which shows a mode that an abrasive grain aggregates when an additive is added. It is a schematic cross section which shows the pattern wafer used in the Example.

  Hereinafter, a polishing liquid, a polishing liquid set, and a substrate polishing method using the same according to embodiments of the present invention will be described in detail.

<Definition>
In this specification, “abrasive liquid” is defined as a composition that touches a surface to be polished during polishing. The phrase “polishing liquid” itself does not limit the components contained in the polishing liquid. As will be described later, the polishing liquid according to the present embodiment contains abrasive grains. Abrasive grains are also referred to as “abrasive particles”, but are referred to herein as “abrasive grains”. Abrasive grains are generally solid particles, and the object to be removed is removed during polishing by the mechanical action of the abrasive grains and the chemical action of the abrasive grains (mainly the surface of the abrasive grains). However, it is not limited to this.

<Polishing liquid>
The polishing liquid according to this embodiment is, for example, a polishing liquid for CMP. Specifically, the polishing liquid according to the present embodiment includes a liquid medium, abrasive grains, a peptide compound having a phenylalanine skeleton, and a polymer, and the polymer has a first functional group directly bonded thereto. A molecular chain and a second molecular chain branched from the first molecular chain, wherein the functional group is selected from the group consisting of a carboxyl group, a carboxylate group, a hydroxyl group, a sulfo group, and a sulfonate group Is at least one kind.

  The essential components and components that can be optionally added are described below.

(Abrasive grains)
The abrasive preferably contains at least one selected from the group consisting of ceria, silica, alumina, zirconia, yttria and a hydroxide of a tetravalent metal element, and more preferably contains a hydroxide of a tetravalent metal element. preferable. The “tetravalent metal element hydroxide” as used herein is a compound containing a tetravalent metal (M ⁴⁺ ) and at least one hydroxide ion (OH ⁻ ). The hydroxide of a tetravalent metal element may contain anions other than hydroxide ions (for example, nitrate ions NO ₃ ⁻ and sulfate ions SO ₄ ²⁻ ). For example, the hydroxide of a tetravalent metal element may contain an anion (for example, nitrate ion NO ₃ ⁻ and sulfate ion SO ₄ ²⁻ ) bonded to the tetravalent metal element.

  Abrasive grains containing a hydroxide of a tetravalent metal element are more reactive with an insulating material (eg, silicon oxide) than abrasive grains made of silica, ceria, etc., and polish the insulating material at a higher polishing rate. can do. An abrasive can be used individually by 1 type or in combination of 2 or more types. Examples of abrasive grains other than abrasive grains containing a hydroxide of a tetravalent metal element include particles containing ceria, silica, alumina, zirconia, yttria and the like. Further, as the abrasive grains containing a tetravalent metal element hydroxide, composite particles containing a tetravalent metal element hydroxide and silica can be used.

  The tetravalent metal element hydroxide is preferably at least one selected from the group consisting of rare earth metal hydroxides and zirconium hydroxides. From the viewpoint of further improving the polishing rate of the insulating material, the tetravalent metal element hydroxide is more preferably a rare earth metal element hydroxide. Examples of rare earth metal elements that can be tetravalent include lanthanoids such as cerium, praseodymium, and terbium. Among these, lanthanoids are preferable and cerium is more preferable from the viewpoint of further improving the polishing rate of the insulating material. A rare earth metal hydroxide and a zirconium hydroxide may be used in combination, or two or more rare earth metal hydroxides may be selected and used.

  When the abrasive grain contains a hydroxide of a tetravalent metal element, the content of the hydroxide of the tetravalent metal element is preferably 80% by mass or more, more preferably 90% by mass or more, based on the whole abrasive grain. 95 mass% or more is still more preferable, 98 mass% or more is especially preferable, and 99 mass% or more is very preferable. From the viewpoint of easy preparation of the polishing liquid and further excellent polishing characteristics, the abrasive grains are composed of hydroxides of tetravalent metal elements (100% by mass of the abrasive grains are hydroxide particles of tetravalent metal elements). Most preferred).

  From the viewpoint of further improving the polishing rate of the insulating material, the lower limit of the average particle size of the abrasive grains in the slurry in the polishing liquid or the polishing liquid set described below is preferably 1 nm or more, more preferably 2 nm or more, and 3 nm or more. Further preferred is 5 nm or more. The upper limit of the average particle size of the abrasive grains is preferably 300 nm or less, more preferably 250 nm or less, further preferably 200 nm or less, particularly preferably 100 nm or less, and particularly preferably 50 nm or less, from the viewpoint of further suppressing the surface to be polished from being scratched. Is very preferred. From the above viewpoint, the average grain size of the abrasive grains is more preferably 1 nm or more and 300 nm or less.

  The “average particle diameter” of the abrasive grains means the average secondary particle diameter of the abrasive grains. The average particle size of the abrasive grains is, for example, a light diffraction scattering type particle size distribution meter (for example, product name: N5 manufactured by Beckman Coulter, Inc., or Malvern Instruments Co., Ltd.) for a slurry in a polishing liquid or a polishing liquid set described later. Manufactured, trade name: Zetasizer 3000HSA).

  In the constituents of the polishing liquid according to this embodiment, the hydroxide of a tetravalent metal element is considered to have a great influence on the polishing characteristics. Therefore, by adjusting the content of the hydroxide of the tetravalent metal element, the chemical interaction between the abrasive grains and the surface to be polished can be improved, and the polishing rate can be further improved. Accordingly, the content of the hydroxide of the tetravalent metal element is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and 0.03% by mass based on the total mass of the polishing liquid. The above is more preferable, and 0.05% by mass or more is particularly preferable. The hydroxide content of the tetravalent metal element makes it easy to avoid agglomeration of the abrasive grains and improves the chemical interaction with the surface to be polished, effectively utilizing the characteristics of the abrasive grains. From the viewpoint of being able to do so, it is preferably 8% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less, particularly preferably 1% by mass or less, and 0.5% by mass or less, based on the total mass of the polishing liquid. Is very preferable, and 0.3% by mass or less is very preferable.

  The lower limit of the abrasive content is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, based on the total mass of the polishing liquid, from the viewpoint of further improving the polishing rate of the insulating material. 0.02% by mass or more is more preferable, 0.03% by mass or more is particularly preferable, 0.04% by mass or more is extremely preferable, and 0.05% by mass or more is very preferable. The upper limit of the content of the abrasive grains is preferably 20% by mass or less, more preferably 15% by mass or less, and more preferably 10% by mass or less, based on the total mass of the polishing liquid, from the viewpoint of increasing the storage stability of the polishing liquid. Further preferred. From the above viewpoint, the content of the abrasive grains is more preferably 0.005% by mass or more and 20% by mass or less based on the total mass of the polishing liquid.

  Further, it is preferable in that the cost and polishing scratches can be further reduced by further reducing the content of abrasive grains. When the content of abrasive grains decreases, the polishing rate of insulating materials and the like also tends to decrease. On the other hand, abrasive grains containing a hydroxide of a tetravalent metal element can obtain a predetermined polishing rate even with a small amount, so that the balance between the polishing rate and the advantage of reducing the content of abrasive grains is balanced. Further, the content of abrasive grains can be further reduced. From such a viewpoint, the content of the abrasive grains is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, particularly preferably 0.5% by mass or less, and 0.3% by mass. % Or less is very preferable.

[Absorbance]
The abrasive preferably contains a hydroxide of a tetravalent metal element and satisfies at least one of the following conditions (a) and (b). The “aqueous dispersion” in which the content of abrasive grains is adjusted to a predetermined amount means a liquid containing a predetermined amount of abrasive grains and water.
(A) Abrasive grains give an absorbance of 1.00 or more to light having a wavelength of 400 nm in an aqueous dispersion in which the content of the abrasive grains is adjusted to 1.0 mass%.
(B) The abrasive gives an absorbance of 1.000 or more to light having a wavelength of 290 nm in an aqueous dispersion in which the content of the abrasive is adjusted to 0.0065% by mass.

Regarding the condition (a), the polishing rate is further improved by using abrasive grains that give an absorbance of 1.00 or more with respect to light having a wavelength of 400 nm in an aqueous dispersion in which the content of abrasive grains is adjusted to 1.0 mass%. be able to. Although this reason is not necessarily clear, this inventor thinks as follows. That is, depending on the production conditions of the tetravalent metal element hydroxide, the tetravalent metal (M ⁴⁺ ), 1 to 3 hydroxide ions (OH ⁻ ), and 1 to 3 anions (X ^c- ) containing M (OH) _a X _b (where a + b × c = 4) is considered to be produced as part of the abrasive grains (note that such particles are also “4”). Abrasive grains containing a hydroxide of a valent metal element). In M (OH) _a X _b , electron-withdrawing anions (X ^c− ) act to improve the reactivity of hydroxide ions, and the amount of M (OH) _a X _b increases. It is considered that the polishing rate is improved along with this. And since the particle | grains containing M (OH) _{a Xb} absorb the light of wavelength 400nm, since the abundance of M (OH) _{a Xb} increases and the light absorbency with respect to the light of wavelength 400nm becomes high, polishing rate Is thought to improve.

It is considered that abrasive grains containing a tetravalent metal element hydroxide may contain not only M (OH) _{a Xb} but also M (OH) ₄ , MO _{2 and the} like. Examples of the anion (X ^c− ) include NO ₃ ⁻ and SO ₄ ²⁻ .

The fact that the abrasive grains containing a hydroxide of a tetravalent metal element contain M (OH) _{a Xb} is that the abrasive grains are thoroughly washed with pure water and then subjected to FT-IR ATR (Fourier transform Infrared Spectrometer Attenuated Total). This can be confirmed by a method of detecting a peak corresponding to an anion (X ^c− ) by a reflection method or a Fourier transform infrared spectrophotometer total reflection measurement method. The presence of an anion (X ^c− ) can also be confirmed by XPS (X-ray Photoelectron Spectroscopy, X-ray photoelectron spectroscopy).

Here, it has been confirmed that the absorption peak at a wavelength of 400 nm of M (OH) _a X _b (for example, M (OH) ₃ X) is much smaller than the absorption peak at a wavelength of 290 nm described later. On the other hand, the present inventor examined the magnitude of the absorbance using an aqueous dispersion having an abrasive content of 1.0% by mass, which has a relatively large abrasive content and is easily detected with a large absorbance. It has been found that when an abrasive that gives an absorbance of 1.00 or more with respect to light having a wavelength of 400 nm is used in an aqueous dispersion, the effect of improving the polishing rate is excellent. In addition, since it is thought that the light absorbency with respect to the light of wavelength 400nm originates in an abrasive grain as above-mentioned, it replaces with the abrasive grain which gives the light absorbency 1.00 or more with respect to the light of wavelength 400nm, and with respect to the light of wavelength 400nm. In the polishing liquid containing a substance that gives an absorbance of 1.00 or more (for example, a yellow pigment component), it is difficult to obtain the above-described improvement effect of the polishing rate.

  The absorbance with respect to light having a wavelength of 400 nm is preferably 1.50 or more, more preferably 1.55 or more, and even more preferably 1.60 or more from the viewpoint of facilitating polishing of the insulating material at a further excellent polishing rate.

Regarding the condition (b), the polishing rate is further improved by using abrasive grains that give an absorbance of 1.000 or more with respect to light having a wavelength of 290 nm in an aqueous dispersion in which the content of abrasive grains is adjusted to 0.0065% by mass. be able to. Although this reason is not necessarily clear, this inventor thinks as follows. That is, a particle containing M (OH) _a X _b (for example, M (OH) ₃ X) generated according to the production conditions of a tetravalent metal element hydroxide has an absorption peak near the wavelength of 290 nm. For example, particles made of Ce ⁴⁺ (OH ⁻ ) ₃ NO ₃ ⁻ have an absorption peak at a wavelength of 290 nm. Therefore, it is considered that the polishing rate is improved as the abundance of M (OH) _{a Xb} increases and the absorbance to light having a wavelength of 290 nm increases.

  Here, the absorbance with respect to light in the vicinity of a wavelength of 290 nm tends to be detected as it exceeds the measurement limit. On the other hand, the present inventors examined the magnitude of absorbance using an aqueous dispersion having an abrasive content of 0.0065% by mass with a relatively small abrasive content and a low absorbance that is easily detected. It has been found that when an abrasive that gives an absorbance of 1.000 or more with respect to light having a wavelength of 290 nm is used in the aqueous dispersion, the effect of improving the polishing rate is excellent. Further, the present inventor has found that the higher the absorbance of abrasive grains with respect to light near a wavelength of 290 nm, the higher the absorbance of the abrasive grains is, apart from light near a wavelength of 400 nm, where the light-absorbing material tends to exhibit a yellow color. It has been found that the yellowness of the polishing liquid and the slurry using the abrasive grains becomes deeper, and that the polishing rate is improved as the yellowness of the polishing liquid and the slurry becomes darker. And this inventor is the light absorbency with respect to the light of wavelength 290nm in the aqueous dispersion whose abrasive grain content is 0.0065 mass%, and the light absorbency with respect to the light of wavelength 400nm in the aqueous dispersion whose abrasive grain content is 1.0 mass%. Was found to correlate.

  The lower limit of the absorbance with respect to light having a wavelength of 290 nm is more preferably 1.050 or more, further preferably 1.100 or more, particularly preferably 1.130 or more, from the viewpoint of polishing the insulating material at a further excellent polishing rate. 150 or more is very preferable. The upper limit of absorbance for light having a wavelength of 290 nm is not particularly limited, but is preferably 10.00, for example.

  When the abrasive that gives an absorbance of 1.00 or more with respect to light having a wavelength of 400 nm gives an absorbance of 1.000 or more with respect to light with a wavelength of 290 nm in an aqueous dispersion in which the content of the abrasive grains is adjusted to 0.0065% by mass. Can polish the insulating material at a further excellent polishing rate.

Further, a hydroxide of a tetravalent metal element (for example, M (OH) _a X _b ) tends not to absorb light having a wavelength of 450 nm or more (particularly, a wavelength of 450 to 600 nm). Accordingly, from the viewpoint of polishing the insulating material at a further excellent polishing rate by suppressing the adverse effect on polishing due to containing impurities, the abrasive grains have a content of the abrasive grains of 0.0065% by mass ( In an aqueous dispersion adjusted to 65 ppm, it is preferable to give an absorbance of 0.010 or less to light having a wavelength of 450 to 600 nm. That is, it is preferable that the light absorbency with respect to all the light in the wavelength range of 450-600 nm does not exceed 0.010 in the water dispersion liquid which adjusted content of the abrasive grain to 0.0065 mass%. The upper limit of absorbance for light having a wavelength of 450 to 600 nm is more preferably less than 0.010. The lower limit of the absorbance with respect to light having a wavelength of 450 to 600 nm is preferably 0.

  The absorbance in the aqueous dispersion can be measured using, for example, a spectrophotometer (device name: U3310) manufactured by Hitachi, Ltd. Specifically, for example, an aqueous dispersion in which the content of abrasive grains is adjusted to 1.0 mass% or 0.0065 mass% is prepared as a measurement sample. About 4 mL of this measurement sample is put into a 1 cm square cell, and the cell is set in the apparatus. Next, the absorbance is measured in the wavelength range of 200 to 600 nm, and the absorbance is determined from the obtained chart.

  If the absorbance is 1.00 or more when the absorbance for light with a wavelength of 400 nm is measured after being diluted excessively so that the content of the abrasive is less than 1.0% by mass, the content of the abrasive is The absorbance may be screened on the assumption that the absorbance is 1.00 or more even when the content is 1.0 mass%. If the absorbance is 1.000 or more when the absorbance for light having a wavelength of 290 nm is measured after being diluted excessively so that the content of the abrasive is less than 0.0065% by mass, the content of the abrasive is Even when the amount is 0.0065% by mass, the absorbance may be screened on the assumption that the absorbance is 1.000 or more. If the absorbance is 0.010 or less when the absorbance for light having a wavelength of 450 to 600 nm is measured by diluting the abrasive grain content to be greater than 0.0065% by mass, the abrasive grains are contained. Even when the amount is 0.0065% by mass, the absorbance may be screened on the assumption that the absorbance is 0.010 or less.

[Light transmittance]
The polishing liquid according to this embodiment preferably has high transparency to visible light (transparent or nearly transparent by visual observation). Specifically, the abrasive contained in the polishing liquid according to this embodiment has a light transmittance of 50% with respect to light having a wavelength of 500 nm in an aqueous dispersion in which the content of the abrasive is adjusted to 1.0 mass%. / Cm or more is preferable. Thereby, since the fall of the grinding | polishing rate resulting from addition of an additive can be further suppressed, it becomes easy to acquire another characteristic, maintaining a grinding | polishing rate. From this viewpoint, the lower limit of the light transmittance is more preferably 60% / cm or more, further preferably 70% / cm or more, particularly preferably 80% / cm or more, extremely preferably 90% / cm or more, 92% / Cm or more is very preferable. The upper limit of the light transmittance is 100% / cm.

  The reason why the decrease in the polishing rate can be suppressed by adjusting the light transmittance of the abrasive grains in this way is not known in detail, but the present inventor thinks as follows. In abrasive grains containing a hydroxide of a tetravalent metal element (cerium or the like), it is considered that the chemical action is more dominant than the mechanical action. Therefore, it is considered that the number of abrasive grains contributes more to the polishing rate than the size of the abrasive grains.

  When the light transmittance is low in an aqueous dispersion having an abrasive grain content of 1.0 mass%, the abrasive grains present in the aqueous dispersion are particles having a large particle diameter (hereinafter referred to as “coarse particles”). It is considered that there are relatively many. When an additive (for example, polyvinyl alcohol (PVA)) is added to a polishing liquid containing such abrasive grains, as shown in FIG. 1, other particles aggregate with coarse particles as nuclei. As a result, the number of abrasive grains acting on the surface to be polished per unit area (the number of effective abrasive grains) is reduced, and the specific surface area of the abrasive grains in contact with the surface to be polished is reduced. Conceivable.

  On the other hand, when the light transmittance is high in an aqueous dispersion having an abrasive grain content of 1.0 mass%, it is considered that the abrasive grains present in the aqueous dispersion are in a state of less “coarse particles”. When the abundance of coarse particles is small in this way, as shown in FIG. 2, even if an additive (for example, polyvinyl alcohol) is added to the polishing liquid, there are few coarse particles that become the core of aggregation. Aggregation between the grains is suppressed, or the size of the aggregated particles is smaller than that of the aggregated particles shown in FIG. As a result, the number of abrasive grains (number of effective abrasive grains) acting on the surface to be polished per unit area is maintained, and the specific surface area of the abrasive grains in contact with the surface to be polished is maintained. It is considered to be.

  According to the inventor's study, even if the polishing liquid has the same particle size measured by a general particle size measuring apparatus, it is visually transparent (high light transmittance) and visually turbid. It has been found that there can be (low light transmittance). From this, it is considered that the coarse particles capable of causing the above-described action contribute to the reduction of the polishing rate even if the amount is so small that it cannot be detected by a general particle size measuring apparatus.

  In addition, even if filtration is repeated a plurality of times to reduce coarse particles, the phenomenon that the polishing rate decreases due to the additive does not improve so much, and the improvement effect of the polishing rate due to absorbance may not be sufficiently exhibited. I know. Then, this inventor discovered that the said problem can be solved by devising the manufacturing method of an abrasive grain etc. and using an abrasive grain with a high light transmittance in an aqueous dispersion.

  The light transmittance is a transmittance for light having a wavelength of 500 nm. The light transmittance can be measured with a spectrophotometer. Specifically, for example, it can be measured with a spectrophotometer U3310 (device name) manufactured by Hitachi, Ltd.

  As a more specific measurement method, an aqueous dispersion in which the content of abrasive grains is adjusted to 1.0% by mass is prepared as a measurement sample. About 4 mL of this measurement sample is put into a 1 cm square cell, and the measurement is performed after setting the cell in the apparatus. In addition, when the content of the abrasive grains is 50% / cm or more in an aqueous dispersion having a content of greater than 1.0% by mass, the light transmittance is also obtained when this is diluted to 1.0% by mass. Is apparently 50% / cm or more. Therefore, the light transmittance can be screened by a simple method by using an aqueous dispersion having an abrasive content greater than 1.0% by mass.

  The absorbance and light transmittance that the abrasive grains contained in the polishing liquid give in the aqueous dispersion are obtained by removing the solid components other than the abrasive grains and the liquid components other than water, and then the aqueous dispersion having a predetermined abrasive grain content. It can be prepared and measured using the aqueous dispersion. Although it depends on the components contained in the polishing liquid, the solid component or liquid component is removed by, for example, centrifugation using a centrifuge capable of applying a gravitational acceleration of several thousand G or less, or applying a gravitational acceleration of tens of thousands G or more. Such as ultracentrifugation using an ultracentrifuge; chromatography methods such as partition chromatography, adsorption chromatography, gel permeation chromatography, ion exchange chromatography; natural filtration, vacuum filtration, pressure filtration, limiting Filtration methods such as external filtration; distillation methods such as vacuum distillation and atmospheric distillation can be used, and these may be combined as appropriate.

  For example, when a compound having a weight average molecular weight of tens of thousands or more (for example, 50,000 or more) is included, a chromatography method, a filtration method and the like can be mentioned, and among these, gel permeation chromatography and ultrafiltration are preferable. When using the filtration method, the abrasive grains contained in the polishing liquid can pass through the filter by setting appropriate conditions. When a compound having a weight average molecular weight of tens of thousands or less (for example, less than 50,000) is used, examples thereof include a chromatography method, a filtration method, and a distillation method, and gel permeation chromatography, ultrafiltration, and vacuum distillation are preferable. When multiple types of abrasive grains are included, filtration methods, centrifugal separation methods and the like can be mentioned. In the case of filtration, in the filtrate, in the liquid phase, abrasive grains containing a hydroxide of a tetravalent metal element are included. More included.

As a method for separating abrasive grains by a chromatography method, for example, an abrasive component can be fractionated and / or other components can be fractionated under the following conditions.
Sample solution: 100 μL of polishing liquid
Detector: manufactured by Hitachi, Ltd., UV-VIS detector, trade name “L-4200”
Wavelength: 400nm
Integrator: Hitachi, Ltd., GPC integrator, product name “D-2500”
Pump: Hitachi, Ltd., trade name “L-7100”
Column: Hitachi Chemical Co., Ltd., packed column for water-based HPLC, trade name “GL-W550S”
Eluent: Deionized water Measurement temperature: 23 ° C
Flow rate: 1 mL / min (pressure is about 40-50 kg / cm ² )
Measurement time: 60 minutes

  In addition, it is preferable to deaerate the eluent using a deaeration device before performing chromatography. When the deaerator cannot be used, it is preferable to deaerate the eluent in advance with ultrasonic waves or the like.

  Depending on the components contained in the polishing liquid, it may not be possible to separate the abrasive components even under the above conditions.In that case, by optimizing the amount of sample solution, column type, eluent type, measurement temperature, flow rate, etc. Can be separated. Further, by adjusting the pH of the polishing liquid, there is a possibility that the distillation time of the components contained in the polishing liquid can be adjusted and separated from the abrasive grains. When there are insoluble components in the polishing liquid, it is preferable to remove the insoluble components by filtration, centrifugation, or the like, if necessary.

[Production method of abrasive grains]
A hydroxide of a tetravalent metal element can be produced by reacting a salt (metal salt) of a tetravalent metal element with an alkali source (base). The hydroxide of the tetravalent metal element is preferably prepared by mixing a salt of the tetravalent metal element and an alkali solution (for example, an alkaline aqueous solution). Thereby, particles having an extremely fine particle diameter can be obtained, and a polishing liquid further excellent in the effect of reducing polishing scratches can be obtained. Such a technique is disclosed in Patent Document 6, for example. A hydroxide of a tetravalent metal element can be obtained by mixing a metal salt solution of a salt of a tetravalent metal element (for example, an aqueous metal salt solution) and an alkali solution. In addition, when supplying at least one of the salt of a tetravalent metal element and an alkali source to a reaction system in a liquid state, the means to stir a liquid mixture is not limited. For example, a method of stirring a mixed solution using a bar-like, plate-like or propeller-like stirrer or a stirring blade that rotates around a rotation axis, a magnetic stirrer that transmits power from the outside of a container, and a rotating magnetic field A method of stirring the liquid mixture by rotating the stirrer, a method of stirring the liquid mixture with a pump installed outside the tank, and a method of stirring the liquid mixture by pressurizing the outside air and blowing it into the tank vigorously It is done. As a salt of a tetravalent metal element, a conventionally known salt can be used without particular limitation, and M (NO ₃ ) ₄ , M (SO ₄ ) ₂ , M (NH ₄ ) ₂ (NO ₃ ) ₆ , M (NH _4). ) ₄ (SO ₄ ) ₄ (M represents a rare earth metal element), Zr (SO ₄ ) ₂ .4H ₂ O, and the like. M is preferably chemically active cerium (Ce).

  Examples of means for adjusting the absorbance and light transmittance include optimization of a method for producing a hydroxide of a tetravalent metal element. Specific examples of the method for changing the absorbance with respect to light having a wavelength of 400 nm and the absorbance with respect to light having a wavelength of 290 nm include selection of an alkali source in an alkali solution, adjustment of a raw material concentration in the metal salt solution and the alkali solution, and metal salt Adjustment of the mixing speed of a solution and an alkali liquid and adjustment of the liquid temperature of the liquid mixture obtained by mixing the salt of a tetravalent metal element and an alkali source are mentioned. Further, as a method of changing the light transmittance for light having a wavelength of 500 nm, specifically, for example, adjustment of the raw material concentration in the metal salt solution and the alkali liquid, adjustment of the mixing speed of the metal salt solution and the alkali liquid, and mixing Adjustment of the stirring speed when performing and adjustment of the liquid temperature of a liquid mixture are mentioned.

  In order to increase the absorbance with respect to light with a wavelength of 400 nm, the absorbance with respect to light with a wavelength of 290 nm, and the light transmittance with respect to light with a wavelength of 500 nm, the method for producing a hydroxide of a tetravalent metal element is made more “gradual”. It is preferable. Here, “slow” means that the increase in pH when the pH of the reaction system increases as the reaction proceeds is moderated (slowed). Conversely, in order to reduce the absorbance for light with a wavelength of 400 nm, the absorbance for light with a wavelength of 290 nm, and the light transmittance for light with a wavelength of 500 nm, the method for producing a hydroxide of a tetravalent metal element is more “violently”. Is preferred. Here, “violently” means that the increase in pH when the pH of the reaction system increases as the reaction progresses is increased (accelerated). In order to adjust these values of absorbance and light transmittance to a predetermined range, it is preferable to optimize the method for producing a hydroxide of a tetravalent metal element with reference to the above tendency. Hereinafter, a method for controlling absorbance and light transmittance will be described in more detail.

{Alkali source}
As the alkali source in the alkali solution, conventionally known ones can be used without particular limitation. Examples of the alkali source include organic bases and inorganic bases. Organic bases include nitrogen-containing organic bases such as guanidine, triethylamine and chitosan; nitrogen-containing heterocyclic organic bases such as pyridine, piperidine, pyrrolidine and imidazole; ammonium carbonate, ammonium hydrogen carbonate, tetramethylammonium hydroxide (TMAH), water Examples thereof include ammonium salts such as tetraethylammonium oxide, tetramethylammonium chloride, and tetraethylammonium chloride. Examples of inorganic bases include inorganic salts of alkali metals such as ammonia, lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate. Etc. An alkali source can be used individually by 1 type or in combination of 2 or more types.

  As the alkali source, ammonia and imidazole are preferable and imidazole is more preferable from the viewpoint of further improving the polishing rate of the insulating material. In order to increase the absorbance with respect to light having a wavelength of 400 nm and the absorbance with respect to light having a wavelength of 290 nm, it is preferable to use an alkali source exhibiting weak basicity as the alkali source. Among the alkali sources, nitrogen-containing heterocyclic organic base is preferable, at least one selected from the group consisting of pyridine, piperidine, pyrrolidine and imidazole is more preferable, at least one selected from the group consisting of pyridine and imidazole is more preferable, Imidazole is particularly preferred.

{concentration}
By controlling the raw material concentrations in the metal salt solution and the alkali solution, the absorbance with respect to light having a wavelength of 400 nm, the absorbance with respect to light with a wavelength of 290 nm, and the light transmittance with respect to light with a wavelength of 500 nm can be changed. Specifically, the absorbance tends to increase by increasing the metal salt concentration of the metal salt solution, and the absorbance tends to increase by decreasing the alkali concentration (base concentration, alkali source concentration) of the alkali solution. There is. In addition, the light transmittance tends to increase by increasing the metal salt concentration, and the light transmittance tends to increase by decreasing the alkali concentration.

  The upper limit of the metal salt concentration in the metal salt solution is preferably 1.000 mol / L or less on the basis of the entire metal salt solution, from the viewpoint of easily achieving both excellent polishing rate and excellent abrasive stability. 0.500 mol / L or less is more preferable, 0.300 mol / L or less is still more preferable, and 0.200 mol / L or less is particularly preferable. The lower limit of the metal salt concentration can suppress the rapid reaction (can moderate the rise in pH), absorbs light with a wavelength of 400 nm, absorbs light with a wavelength of 290 nm, and transmits light with a wavelength of 500 nm. From the viewpoint of increasing the rate, 0.010 mol / L or more is preferable, 0.020 mol / L or more is more preferable, and 0.030 mol / L or more is still more preferable based on the entire metal salt solution.

  The upper limit of the alkali concentration in the alkali solution is preferably 15.0 mol / L or less, more preferably 12.0 mol / L or less, based on the whole alkali solution, from the viewpoint of suppressing a rapid reaction. 0 mol / L or less is more preferable, and 5.0 mol / L or less is particularly preferable. The lower limit of the alkali concentration is not particularly limited, but is preferably 0.001 mol / L or more on the basis of the entire alkali solution from the viewpoint of excellent productivity.

  It is preferable that the alkali concentration in the alkaline solution is appropriately adjusted depending on the selected alkali source. For example, in the case of an alkali source in which the pKa of the conjugate acid of the alkali source is 20 or more, the upper limit of the alkali concentration is 0.10 mol / L on the basis of the entire alkali solution from the viewpoint of suppressing a rapid reaction. The following is preferable, 0.05 mol / L or less is more preferable, and 0.01 mol / L or less is still more preferable. The lower limit of the alkali concentration is not particularly limited, but from the viewpoint of suppressing the amount of the solution used for obtaining a predetermined amount of tetravalent metal element hydroxide, 0.001 mol / L or more based on the entire alkali solution is used. preferable.

  In the case of an alkali source in which the pKa of the conjugate acid of the alkali source is 12 or more and less than 20, the upper limit of the alkali concentration is 1.0 mol / L on the basis of the entire alkali solution from the viewpoint of suppressing rapid reaction. The following is preferable, 0.50 mol / L or less is more preferable, and 0.10 mol / L or less is more preferable. The lower limit of the alkali concentration is not particularly limited, but from the viewpoint of suppressing the amount of the solution used for obtaining a predetermined amount of tetravalent metal element hydroxide, 0.01 mol / L or more based on the entire alkali solution is used. preferable.

  In the case of an alkali source in which the pKa of the conjugate acid of the alkali source is less than 12, the upper limit of the alkali concentration is 15.0 mol / L or less on the basis of the whole alkali solution from the viewpoint of suppressing a rapid reaction. Preferably, 10.0 mol / L or less is more preferable, and 5.0 mol / L or less is still more preferable. The lower limit of the alkali concentration is not particularly limited, but from the viewpoint of suppressing the amount of the solution used for obtaining a predetermined amount of the hydroxide of the tetravalent metal element, it is 0.10 mol / L or more based on the total amount of the alkali solution. preferable.

  Examples of the alkali source in which the pKa of the conjugate acid of the alkali source is 20 or more include 1,8-diazabicyclo [5.4.0] undec-7-ene (pKa: 25). Examples of the alkali source in which the pKa of the conjugate acid of the alkali source is 12 or more and less than 20 include potassium hydroxide (pKa: 16) and sodium hydroxide (pKa: 13). Examples of the alkali source in which the pKa of the conjugate acid of the alkali source is less than 12 include ammonia (pKa: 9) and imidazole (pKa: 7). The pKa value of the conjugate acid of the alkali source used is not particularly limited as long as the alkali concentration is appropriately adjusted, but the pKa of the conjugate acid of the alkali source is preferably less than 20, preferably less than 12. Is more preferably less than 10, and particularly preferably less than 8.

{Mixing speed}
By controlling the mixing speed of the metal salt solution and the alkali solution, the absorbance with respect to light with a wavelength of 400 nm, the absorbance with respect to light with a wavelength of 290 nm, and the light transmittance with respect to light with a wavelength of 500 nm can be changed. As a tendency, the absorbance and the light transmittance are increased by making the increase in pH gentle (slow). More specifically, the absorbance tends to increase by reducing the mixing speed, and the absorbance tends to decrease by increasing the mixing speed. Moreover, there exists a tendency for the light transmittance to become high by making a mixing speed slow, and there exists a tendency for the light transmittance to become low by making a mixing speed fast.

The upper limit of the mixing speed is preferably 5.00 × 10 ⁻³ m ³ / min (5 L / min) or less from the viewpoint of further suppressing the rapid progress of the reaction and further suppressing the local reaction bias. 1.00 × 10 ⁻³ m ³ / min (1 L / min) or less, more preferably 5.00 × 10 ⁻⁴ m ³ / min (500 mL / min) or less, and 1.00 × 10 ^−4. m ³ / min (100 mL / min) or less is particularly preferable. The lower limit of the mixing speed is not particularly limited, but is preferably 1.00 × 10 ⁻⁷ m ³ / min (0.1 mL / min) or more from the viewpoint of excellent productivity.

{Stirring speed}
By controlling the stirring speed when mixing the metal salt solution and the alkali solution, the light transmittance with respect to light having a wavelength of 500 nm can be changed. Specifically, the light transmittance tends to increase by increasing the stirring speed, and the light transmittance tends to decrease by decreasing the stirring speed.

The lower limit of the stirring speed can further suppress the deviation of the response in the local, and, from the viewpoint of excellent mixing efficiency, preferably 30min ^-1 or more, more preferably 50min ^-1 or more, 80min ^-1 or more is more preferable. The upper limit of the stirring speed is not particularly limited and needs to be appropriately adjusted depending on the size and shape of the stirring blade, but is preferably 1000 min ⁻¹ or less from the viewpoint of suppressing liquid splashing.

{Liquid temperature (synthesis temperature)}
By controlling the liquid temperature of the mixture obtained by mixing a salt of a tetravalent metal element and an alkali source, the absorbance for light with a wavelength of 400 nm, the absorbance for light with a wavelength of 290 nm, and the light transmittance for light with a wavelength of 500 nm are obtained. It is possible to obtain an abrasive that can be changed and can achieve a desired polishing rate and storage stability. Specifically, the absorbance tends to increase by lowering the liquid temperature, and the absorbance tends to decrease by increasing the liquid temperature. Moreover, the light transmittance tends to increase by lowering the liquid temperature, and the light transmittance tends to decrease by increasing the liquid temperature.

  Liquid temperature is the temperature in the liquid mixture which can be read, for example by installing a thermometer in a liquid mixture, and it is preferable that it is 0-100 degreeC. The upper limit of the liquid temperature is preferably 100 ° C. or less, more preferably 60 ° C. or less, still more preferably 55 ° C. or less, particularly preferably 50 ° C. or less, and particularly preferably 45 ° C. or less, from the viewpoint of suppressing rapid reaction. preferable. The lower limit of the liquid temperature is preferably 0 ° C. or higher, more preferably 10 ° C. or higher, and still more preferably 20 ° C. or higher, from the viewpoint of allowing the reaction to proceed easily.

  The tetravalent metal element hydroxide synthesized by the above method may contain impurities (for example, metal impurities), but the impurities can be removed by washing. For washing the tetravalent metal element hydroxide, a method of repeating solid-liquid separation several times by centrifugation or the like can be used. Moreover, it can also wash | clean by centrifugation, dialysis, ultrafiltration, the removal of the ion by an ion exchange resin, etc. By removing the impurities, the absorbance with respect to light having a wavelength of 450 to 600 nm can be adjusted.

  When the abrasive grains obtained above are agglomerated, they can be dispersed in water by an appropriate method. As a method for dispersing abrasive grains in water, which is the main dispersion medium, mechanical dispersion treatment using a homogenizer, an ultrasonic disperser, a wet ball mill, or the like may be used in addition to the dispersion treatment using a stirrer. For the dispersion method and the particle size control method, for example, the method described in Non-Patent Document 1 can be used. The dispersibility of the abrasive grains can also be improved by performing the above-described cleaning treatment to lower the electrical conductivity of the dispersion liquid containing abrasive grains (for example, 500 mS / m or less). Therefore, the cleaning process may be applied as a dispersion process, and the cleaning process and the dispersion process may be used in combination.

(Additive)
The polishing liquid according to this embodiment contains an additive. Here, “additive” means polishing other than the liquid medium and abrasive grains in order to adjust polishing characteristics such as polishing rate and polishing selectivity; polishing liquid characteristics such as abrasive dispersibility and storage stability. It refers to the substance contained in the liquid.

[Essential additive: Peptide compound]
The polishing liquid according to this embodiment contains a peptide compound having a phenylalanine skeleton as an essential additive. The peptide compound having a phenylalanine skeleton has an effect of suppressing the polishing rate of the stopper material (for example, silicon nitride) from becoming excessively high (effect as a polishing inhibitor). This is because the polishing rate of the stopper material (for example, silicon nitride) is suppressed by the amide bond (peptide bond etc.) portion (—CONH—) in the peptide compound acting as an adsorbing group for the stopper material (for example, silicon nitride). Presumed to be. Further, by using a peptide compound having a phenylalanine skeleton, high flatness can be obtained by suppressing polishing of an insulating material (eg, silicon oxide) after exposure of a stopper material (eg, silicon nitride). This is because the amide bond (peptide bond, etc.) part in the peptide compound is adsorbed and coated on the insulating material, and the aromatic ring in the phenylalanine skeleton covers the surface of the insulating material. It is presumed that the progress of polishing by the above is moderated and the polishing rate is prevented from becoming excessively high.

  A peptide compound having a phenylalanine skeleton is a compound having a phenylalanine skeleton (a skeleton (structure) derived from phenylalanine) and an amide bond (such as a peptide bond), and can also be interpreted as a phenylalanine derivative. The peptide compound having a phenylalanine skeleton only needs to have at least one phenylalanine skeleton and an amide bond (such as a peptide bond). The aromatic ring in the phenylalanine skeleton may have a substituent. As a peptide compound having a phenylalanine skeleton, a dipeptide compound having a phenylalanine skeleton is preferable, and a compound in which a phenylalanine skeleton and an amino acid-derived structure are bonded via a peptide bond is more preferable. Examples of the dipeptide compound having a phenylalanine skeleton include glycyl-DL-phenylalanine, DL-alanyl-DL-phenylalanine, and NL-α-aspartyl-L-phenylalanine-1-methyl.

  The said peptide compound can be used individually by 1 type or in combination of 2 or more types in order to adjust polishing characteristics, such as flatness.

  The lower limit of the content of the peptide compound is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, based on the total mass of the polishing liquid, from the viewpoint of further improving polishing selectivity and flatness. 0.01% by mass or more is more preferable, and 0.1% by mass or more is particularly preferable. The upper limit of the content of the peptide compound is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, based on the total mass of the polishing liquid, from the viewpoint of easily obtaining an appropriate polishing rate. 5 mass% or less is still more preferable, and 0.3 mass% or less is especially preferable. In addition, when using a some compound as said peptide compound, it is preferable that the sum total of content of each compound satisfy | fills the said range.

[Essential additive: Branched polymer]
The polishing liquid according to this embodiment includes, as essential additives, a branched polymer having a first molecular chain to which a functional group is directly bonded and a second molecular chain branched from the first molecular chain ( A compound corresponding to the peptide compound is excluded). The functional group is at least one selected from the group consisting of a carboxyl group, a carboxylate group, a hydroxyl group, a sulfo group, and a sulfonate group. Examples of salts of carboxylate groups and sulfonate groups include sodium salts, potassium salts, ammonium salts, and amine salts. The branched polymer has an effect of suppressing the polishing rate of the stopper material (for example, silicon nitride) from becoming excessively high (effect as a polishing inhibitor). Further, by using the branched polymer, high flatness can be obtained by suppressing polishing of the insulating material (for example, silicon oxide) after the stopper is exposed. When the specific functional group directly bonded to the first molecular chain is adsorbed and coated on the insulating material and the stopper material, the progress of polishing by the abrasive grains is alleviated and the polishing rate is prevented from becoming excessively high. Presumed to be.

  The branched polymer is not particularly limited as long as it is a polymer having a first molecular chain directly bound to the specific functional group and a second molecular chain branched from the first molecular chain. be able to. Examples of the branched polymer include so-called comb polymers. An atom constituting a functional group directly bonded to the first molecular chain does not correspond to an atom constituting the second molecular chain. The phrase “functional group is directly bonded to the first molecular chain” means that the functional group is bonded to the atoms constituting the first molecular chain without any other atoms. The first molecular chain may be the longest molecular chain among the molecular chains constituting the branched polymer. The second molecular chain is a side chain of the first molecular chain. The first molecular chain and / or the second molecular chain may be a carbon chain.

  The first molecular chain of the branched polymer is easy to polish the insulating material at a high polishing rate, and from the viewpoint of easily suppressing the polishing rate of the stopper material. It is preferable to include at least one selected from the group consisting of a structural unit, a structural unit derived from acrylic acid, a structural unit derived from methacrylic acid, a structural unit derived from maleic acid, and a structural unit derived from vinyl acetate. Examples of the olefin include ethylene and propylene. In addition, the first molecular chain of the branched polymer is easy to polish the insulating material at a high polishing rate, and from the viewpoint of easily suppressing the polishing rate of the stopper material, the polyester chain, the polyurethane chain, and the polyamide chain. It is preferable to include at least one selected from the group consisting of The first molecular chain of the branched polymer facilitates polishing of the insulating material at a high polishing rate, and from the viewpoint of easily suppressing the polishing rate of the stopper material, a polystyrene chain, a polyolefin chain (polyethylene chain, Polypropylene chain, etc.), polyester chain, polyurethane chain, polyamide chain, polyacrylic acid chain (polyacrylic chain), polymethacrylic acid chain (polymethacrylic chain), polymaleic acid chain, polyvinyl acetate chain, and these polymer chains More preferably, it contains at least one selected from the group consisting of copolymer chains having structural units.

  In the copolymer chain, the arrangement of the structural units is arbitrary. As the copolymer chain, for example, (a) a block copolymer chain in which the same type of structural units are continuous, (b) a random copolymer chain in which the structural units A and B are particularly ordered, and (C) An alternating copolymer chain in which structural units A and B are alternately arranged can be mentioned.

  The branched polymer may have at least one selected from the group consisting of a hydrophilic molecular chain and a hydrophobic molecular chain in the first molecular chain and / or the second molecular chain. The branched polymer may have a hydrophilic structural unit and / or a hydrophilic polymer chain in the first molecular chain and / or the second molecular chain, and may have a hydrophobic structural unit and / or a hydrophobic structural unit. It may have a sex polymer chain. Examples of the hydrophilic structural unit include a structural unit derived from vinyl alcohol, a structural unit derived from vinyl pyrrolidone, a structural unit derived from acrylic acid, a structural unit derived from methacrylic acid, and a structural unit derived from maleic acid. Examples of the hydrophilic polymer chain include a polyether chain, a polyvinyl alcohol chain, and a polyvinyl pyrrolidone chain. Examples of the hydrophobic structural unit include a structural unit derived from styrene, a structural unit derived from olefin, and a structural unit derived from vinyl acetate. Examples of the hydrophobic polymer chain include a polyester chain, a polyurethane chain, and a polyamide chain.

  From the viewpoint that the first molecular chain of the branched polymer makes it easy to polish the insulating material at a high polishing rate while suppressing aggregation of abrasive grains, and also makes it easy to sufficiently suppress the polishing rate of the stopper material. It is preferable to include at least one selected from the group consisting of a polymaleic acid chain and a copolymer chain having a hydrophobic structural unit and a hydrophilic structural unit. As a copolymer chain having a hydrophobic structural unit and a hydrophilic structural unit, it is easy to polish an insulating material at a high polishing rate while suppressing aggregation of abrasive grains, and a polishing rate of a stopper material is sufficient. From the viewpoint of being easily suppressed, at least one selected from the group consisting of a styrene-acrylic acid copolymer chain, a styrene-methacrylic acid copolymer chain, and a styrene-maleic acid copolymer chain is preferable.

  The second molecular chain preferably contains at least one selected from the group consisting of a hydrophilic molecular chain and a hydrophobic molecular chain from the viewpoint of easily maintaining the dispersion stability of the abrasive grains. Thereby, polishing selectivity and flatness can be further improved while suppressing aggregation of abrasive grains (for example, abrasive grains containing a hydroxide of a tetravalent metal element).

  The hydrophilic molecular chain suppresses the aggregation of abrasive grains and facilitates polishing of the insulating material at a high polishing rate, and from the viewpoint of sufficiently suppressing the polishing rate of the stopper material, a polyether chain, polyvinyl alcohol. It preferably contains at least one selected from the group consisting of a chain and a polyvinylpyrrolidone chain, and more preferably contains a polyether chain. The polyether chain may contain a polyoxyalkylene chain from the viewpoint of easily polishing the insulating material at a high polishing rate while suppressing aggregation of abrasive grains and easily suppressing the polishing rate of the stopper material. Preferably, it contains a polyoxyethylene chain, a polyoxypropylene chain, or a polyoxyethylene-polyoxypropylene chain.

  Hydrophobic molecular chain is a structural unit derived from styrene from the viewpoint of easily polishing the insulating material at a high polishing rate while suppressing aggregation of abrasive grains, and easily suppressing the polishing rate of the stopper material. At least selected from the group consisting of structural units derived from olefins, structural units derived from acrylic acid, structural units derived from methacrylic acid, structural units derived from maleic acid, structural units derived from vinyl acetate, polyester chains, polyurethane chains and polyamide chains. 1 type is preferably included, and at least one selected from the group consisting of polystyrene chain, polyolefin chain (for example, polyethylene chain and polypropylene chain), polyvinyl acetate chain, polyester chain, polyurethane chain and polyamide chain is more preferable. Selected from the group consisting of polystyrene chains and polyolefin chains More preferably contains at least one member, it is particularly preferred to include a polystyrene chain.

  As the branched polymer, those having the above-described structure can be used from those generally used as a dispersing agent for particles and the like. For example, “DISPERBYK-190” (manufactured by BYK-Chemie GmbH, polyalkylene glycol-modified styrene-maleic acid copolymer), “TEGO Dispers 755W” (manufactured by Evonik Industries, polyethylene glycol-modified styrene-maleic acid copolymer), etc. Commercially available wetting and dispersing agents can be used. DISPERBYK-190 and TEGO Dispers 755W are polymers having a branched (comb-type) structure, having a styrene-maleic acid copolymer chain, and having a functional group directly bonded to the copolymer chain. It has a carboxyl group, and has a hydrophilic polyoxyalkylene chain branched from the copolymer chain (TEGO Dispers 755W is a polyoxyethylene chain).

  The branched polymer can be used singly or in combination of two or more for the purpose of adjusting polishing properties such as polishing selectivity and flatness.

The upper limit of the weight average molecular weight of the branched polymer is not particularly limited, but is preferably 200000 or less, more preferably 150,000 or less, and even more preferably 100000 or less, from the viewpoint that appropriate workability and foamability are easily obtained. 80000 or less is particularly preferable, 70000 or less is very preferable, 50000 or less is very preferable, and 30000 or less is even more preferable. From the viewpoint of further improving polishing selectivity and flatness, the lower limit of the weight average molecular weight of the branched polymer is preferably 200 or more, more preferably 400 or more, still more preferably 500 or more, particularly preferably 1000 or more, and 2000 or more. Is very preferred. In addition, a weight average molecular weight can be measured on condition of the following by the gel permeation chromatography method (GPC) using the calibration curve of a standard polystyrene, for example.
Equipment used: ACQUITY APC system [manufactured by Waters]
Column: Waters ACQUITY APC XT 200 + Waters ACQUITY APC XT 45 + Waters ACQUITY APC XT 45 [trade name, manufactured by Waters, 3 in total]
Eluent: Tetrahydrofuran Column temperature: 45 ° C
Detector: ACQUITY Differential refractometer (RI) detector [manufactured by Waters]
RI temperature: 45 ° C
Data processing: Empower 3 [manufactured by Waters]
Injection volume: 10 μL
Standard materials: polystyrene, Shodex STANDARD SM-105 [manufactured by Showa Denko KK]

  The lower limit of the content of the branched polymer is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, based on the total mass of the polishing liquid, from the viewpoint of further improving polishing selectivity and flatness. Preferably, 0.01 mass% or more is further more preferable, and 0.03 mass% or more is particularly preferable. The upper limit of the content of the branched polymer is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, based on the total mass of the polishing liquid, from the viewpoint of easily obtaining an appropriate polishing rate. .1% by mass or less is more preferable, and 0.05% by mass or less is particularly preferable. In addition, when using a some compound as said branched polymer, it is preferable that the sum total of content of each compound satisfy | fills the said range.

[Optional additives]
The polishing liquid according to the present embodiment further contains an optional additive (excluding the peptide compound or the compound corresponding to the branched polymer) in addition to the essential additive for the purpose of adjusting the polishing characteristics. May be. Examples of optional additives include polyoxyalkylene compounds, cationic polymers, carboxylic acids, amino acids, water-soluble polymers, oxidizing agents (for example, hydrogen peroxide), and the like. Each of these additives can be used alone or in combination of two or more.

  The optional additive has an effect of further suppressing an excessive increase in the polishing rate of the stopper material (for example, silicon nitride). Further, by using an optional additive, it is possible to obtain higher flatness by suppressing polishing of the insulating material (for example, silicon oxide) after the exposure of the stopper. It is presumed that when the optional additive covers the insulating material and the stopper material, the progress of polishing by the abrasive grains is alleviated and the polishing rate is prevented from becoming excessively high.

  Examples of the polyoxyalkylene compound include polyalkylene glycol and polyoxyalkylene derivatives.

  Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polybutylene glycol and the like. The polyalkylene glycol is preferably at least one selected from the group consisting of polyethylene glycol and polypropylene glycol, and more preferably polyethylene glycol.

  The polyoxyalkylene derivative is, for example, a compound obtained by introducing a functional group or a substituent into polyalkylene glycol, or a compound obtained by adding polyalkylene oxide to an organic compound. Examples of the functional group or substituent include an alkyl ether group, an alkyl phenyl ether group, a phenyl ether group, a styrenated phenyl ether group, a glyceryl ether group, an alkyl amine group, a fatty acid ester group, and a glycol ester group. Examples of the polyoxyalkylene derivative include polyoxyethylene alkyl ether, polyoxyethylene bisphenol ether (for example, BA glycol series manufactured by Nippon Emulsifier Co., Ltd.), polyoxyethylene styrenated phenyl ether (for example, manufactured by Kao Corporation, Emulgen Series), polyoxyethylene alkyl phenyl ether (for example, Neugen EA series manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), polyoxyalkylene polyglyceryl ether (for example, SC-E series and SC-P series manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) , Polyoxyethylene sorbitan fatty acid ester (for example, Daiichi Kogyo Seiyaku Co., Ltd., Sorgen TW series), polyoxyethylene fatty acid ester (for example, Kao Corporation, Emanon series), Reoxyethylene alkylamine (for example, Amiradin D manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and other polyalkylene oxide-added compounds (for example, Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd. and Nippon Emulsifier Co., Ltd.) Manufactured, TMP series).

The upper limit of the weight average molecular weight of the polyoxyalkylene compound is not particularly limited, but is preferably 100000 or less, more preferably 50000 or less, and still more preferably 20000 or less, from the viewpoint that appropriate workability and foamability are easily obtained. 10000 or less is particularly preferable, and 5000 or less is very preferable. The lower limit of the weight average molecular weight of the polyoxyalkylene compound is preferably 200 or more, more preferably 400 or more, and still more preferably 500 or more, from the viewpoint of further improving polishing selectivity and flatness. In addition, a weight average molecular weight can be measured on condition of the following by the gel permeation chromatography method (GPC) using the calibration curve of a standard polystyrene, for example.
Equipment used: Hitachi L-6000 type [manufactured by Hitachi, Ltd.]
Column: Gel pack GL-R420 + Gel pack GL-R430 + Gel pack GL-R440 [Hitachi Chemical Co., Ltd., trade name, total of 3]
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 1.75 mL / min Detector: L-3300RI [manufactured by Hitachi, Ltd.]

  The lower limit of the content of the polyoxyalkylene compound is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, based on the total mass of the polishing liquid, from the viewpoint of further improving polishing selectivity and flatness. Preferably, 0.1% by mass or more is more preferable, and 0.3% by mass or more is particularly preferable. The upper limit of the content of the polyoxyalkylene compound is preferably 5% by mass or less, more preferably 2% by mass or less, and more preferably 1% by mass or less, based on the total mass of the polishing liquid, from the viewpoint of easily obtaining an appropriate polishing rate. Further preferred. In addition, when using a some compound as a polyoxyalkylene compound, it is preferable that the sum total of content of each compound satisfy | fills the said range.

  The cationic polymer is defined as a polymer having a cationic group or a group that can be ionized into a cationic group in the main chain or the side chain. Examples of the cationic group include an amino group, an imino group, and a cyano group.

  The cationic polymer has an effect of further suppressing an excessive increase in the polishing rate of the stopper material when used in combination with the polyoxyalkylene compound. In addition, the cationic polymer can suppress the decrease in the polishing rate of the insulating material due to the polyoxyalkylene compound covering the insulating material excessively in addition to the stopper material, and improves the polishing rate of the insulating material. There is also an effect. Therefore, when the polyoxyalkylene compound and the cationic polymer are used in combination, the cationic polymer interacts with the polyoxyalkylene compound, so that the polishing rate of the stopper material can be further suppressed, and the insulating material It is considered that the polishing rate can be improved.

  The cationic polymer can be obtained, for example, by polymerizing at least one monomer component selected from the group consisting of allylamine, diallylamine, vinylamine, ethyleneimine, and derivatives thereof. The cationic polymer is, for example, at least one selected from the group consisting of an allylamine polymer, a diallylamine polymer, a vinylamine polymer, and an ethyleneimine polymer.

  The allylamine polymer is a polymer obtained by polymerizing allylamine or a derivative thereof. Examples of the allylamine derivative include alkoxycarbonylated allylamine, methylcarbonylated allylamine, aminocarbonylated allylamine, ureated allylamine and the like.

  A diallylamine polymer is a polymer obtained by polymerizing diallylamine or a derivative thereof. Examples of diallylamine derivatives include methyl diallylamine, diallyldimethylammonium salt, diallylmethylethylammonium salt, acylated diallylamine, aminocarbonylated diallylamine, alkoxycarbonylated diallylamine, aminothiocarbonylated diallylamine, hydroxyalkylated diallylamine, and the like. Examples of the ammonium salt include ammonium chloride and ammonium alkyl sulfate (for example, ammonium ethyl sulfate).

  The vinylamine polymer is a polymer obtained by polymerizing vinylamine or a derivative thereof. Examples of the vinylamine derivative include alkylated vinylamine, amidated vinylamine, ethylene oxideated vinylamine, propylene oxided vinylamine, alkoxylated vinylamine, carboxymethylated vinylamine, acylated vinylamine, and ureaated vinylamine.

  The ethyleneimine polymer is a polymer obtained by polymerizing ethyleneimine or a derivative thereof. Examples of the ethyleneimine derivative include aminoethylated acrylic polymer, alkylated ethyleneimine, ureaated ethyleneimine, propylene oxideated ethyleneimine and the like.

  The cationic polymer may have structural units derived from monomer components other than allylamine, diallylamine, vinylamine, ethyleneimine, and derivatives thereof, such as acrylamide, dimethylacrylamide, diethylacrylamide, hydroxyethylacrylamide, acrylic acid. And may have a structural unit derived from methyl acrylate, methacrylic acid, maleic acid, sulfur dioxide or the like.

  The cationic polymer may be a homopolymer of allylamine, diallylamine, vinylamine or ethyleneimine (polyallylamine, polydiallylamine, polyvinylamine or polyethyleneimine), derived from allylamine, diallylamine, vinylamine, ethyleneimine or derivatives thereof. A copolymer having the following structural unit may also be used. In the copolymer, the arrangement of structural units is arbitrary. Examples of the copolymer include (a) a block copolymer in which the same type of structural units are continuous, (b) a random copolymer in which the structural units A and B are particularly ordered, and (c) structural units. Examples thereof include an alternating copolymer in which A and structural units B are alternately arranged.

  The lower limit of the weight average molecular weight of the cationic polymer is preferably 100 or more, more preferably 300 or more, and even more preferably 500 or more, from the viewpoint of further improving the polishing selectivity of the insulating material with respect to the stopper material. The upper limit of the weight average molecular weight of the cationic polymer is preferably 1000000 or less, more preferably 600000 or less, and even more preferably 300000 or less, from the viewpoint of further improving the polishing selectivity of the insulating material with respect to the stopper material.

In addition, the weight average molecular weight of a cationic polymer can be measured on condition of the following by the gel permeation chromatography method (GPC) using the calibration curve of a standard polystyrene, for example.
Equipment used: Hitachi L-6000 type [manufactured by Hitachi, Ltd.]
Column: Gel pack GL-R420 + Gel pack GL-R430 + Gel pack GL-R440 [trade name, manufactured by Hitachi Chemical Co., Ltd., total of 3]
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 1.75 mL / min Detector: L-3300RI [manufactured by Hitachi, Ltd.]

  From the viewpoint of further improving the polishing selectivity and flatness, the lower limit of the content of the cationic polymer is preferably 0.0001% by mass or more, more preferably 0.0002% by mass or more, based on the total mass of the polishing liquid. Preferably, 0.0005 mass% or more is more preferable. From the viewpoint of further improving the polishing selectivity, the upper limit of the content of the cationic polymer is preferably 5% by mass or less, more preferably 3% by mass or less, and more preferably 1% by mass or less, based on the total mass of the polishing liquid. More preferably, 0.5% by mass or less is particularly preferable, 0.1% by mass or less is very preferable, 0.05% by mass or less is very preferable, and 0.01% by mass or less is even more preferable. In addition, when using a some compound as a cationic polymer, it is preferable that the sum total of content of each compound satisfy | fills the said range. The content of the cationic polymer depends on the insulating material production method (type and filming conditions) from the viewpoint of further improving the polishing speed of the insulating material, the polishing selectivity of the insulating material with respect to the stopper material, and the flatness. It is preferable to adjust appropriately.

  When using a carboxylic acid, an amino acid, a water-soluble polymer or an oxidizing agent, the content is 0 on the basis of the total mass of the polishing liquid from the viewpoint of obtaining the additive effect while suppressing the precipitation of the abrasive grains. It is preferably 0.0001% by mass or more and 10% by mass or less. In addition, when using a some compound as these additives, it is preferable that the sum total of content of each compound satisfy | fills the said range.

  Carboxylic acid has the effect of stabilizing the pH and further improving the polishing rate of the insulating material. Examples of the carboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, cyclohexanecarboxylic acid, caproic acid, and lactic acid.

  Amino acids have the effect of improving the dispersibility of abrasive grains (for example, abrasive grains containing a hydroxide of a tetravalent metal element) and further improving the polishing rate of the insulating material. Amino acids include arginine, lysine, aspartic acid, glutamic acid, asparagine, glutamine, histidine, proline, tyrosine, tryptophan, serine, threonine, glycine, alanine, β-alanine, methionine, cysteine, phenylalanine, leucine, valine, isoleucine, etc. Can be mentioned.

  The water-soluble polymer has flatness, in-plane uniformity, polishing selectivity of silicon oxide with respect to silicon nitride (silicon oxide polishing rate / silicon nitride polishing rate), polishing selectivity of silicon oxide with respect to polysilicon (of silicon oxide) This has the effect of adjusting polishing characteristics such as (polishing rate / polysilicon polishing rate). Here, the “water-soluble polymer” is defined as a polymer that dissolves 0.1 g or more in 100 g of water. The polymer corresponding to the branched polymer, polyoxyalkylene compound or cationic polymer is not included in the “water-soluble polymer”.

  The water-soluble polymer is not particularly limited, and is an acrylic polymer such as polyacrylamide and polydimethylacrylamide; polysaccharides such as alginic acid, pectic acid, carboxymethylcellulose, agar, curdlan, dextrin, cyclodextrin, and pullulan; polyvinyl alcohol Vinyl polymers such as polyvinylpyrrolidone and polyacrolein; glycerin polymers such as polyglycerol and polyglycerol derivatives; polyethylene glycol and the like. A water-soluble polymer can be used individually by 1 type or in combination of 2 or more types.

  When using a water-soluble polymer, the lower limit of the content of the water-soluble polymer is based on the total mass of the polishing liquid from the viewpoint of obtaining the effect of adding the water-soluble polymer while suppressing sedimentation of abrasive grains. 0.0001 mass% or more is preferable, 0.001 mass% or more is more preferable, and 0.01 mass% or more is still more preferable. The upper limit of the content of the water-soluble polymer is preferably 10% by mass or less, preferably 5% by mass based on the total mass of the polishing liquid from the viewpoint of obtaining the effect of adding the water-soluble polymer while suppressing sedimentation of the abrasive grains. % Or less is more preferable, 1 mass% or less is further more preferable, and 0.5 mass% or less is particularly preferable. When using a some compound as water-soluble polymer, it is preferable that the sum total of content of each compound satisfy | fills the said range.

(Liquid medium)
The liquid medium in the polishing liquid according to this embodiment is not particularly limited, but water such as deionized water or ultrapure water is preferable. The content of the liquid medium may be the remainder of the polishing liquid excluding the content of other components and is not particularly limited.

(Polishing liquid characteristics)
The pH (25 ° C.) of the polishing liquid according to this embodiment is preferably 2.0 to 8.0 from the viewpoint of further excellent storage stability of the polishing liquid and polishing suppression effect of the stopper material. The pH of the polishing liquid mainly affects the polishing rate. The lower limit of the pH is more preferably 2.5 or more, further preferably 3.0 or more, particularly preferably 3.5 or more, and extremely preferably 4.0 or more from the viewpoint of further improving the polishing rate of the insulating material. The upper limit of pH is more preferably 7.5 or less, and even more preferably 7.0 or less, from the viewpoint of further improving the polishing suppression effect of the stopper material.

  The pH of the polishing liquid can be adjusted by an acid component such as an inorganic acid or an organic acid; an alkali component such as ammonia, sodium hydroxide, tetramethylammonium hydroxide (TMAH), or imidazole (for example, 2-methylimidazole). A buffer may be added to stabilize the pH. Moreover, you may add a buffer as a buffer (liquid containing a buffer). Examples of such a buffer include acetate buffer and phthalate buffer.

  The pH of the polishing liquid according to this embodiment can be measured with a pH meter (for example, model number PHL-40 manufactured by Electrochemical Instrument Co., Ltd.). Specifically, for example, after calibrating two pH meters using a phthalate pH buffer solution (pH: 4.01) and a neutral phosphate pH buffer solution (pH: 6.86) as standard buffers, Then, the pH meter electrode is put in the polishing liquid, and the value after 2 minutes has passed and stabilized is measured. At this time, both the standard buffer solution and the polishing solution are set to 25 ° C.

  The polishing liquid according to this embodiment may be stored as a one-part polishing liquid containing at least abrasive grains, the peptide compound, the branched polymer, and a liquid medium, and a slurry (first liquid). Mixing the additive liquid (second liquid) and storing it as a polishing liquid set of multiple liquid type (for example, two liquid type) in which the constituents of the polishing liquid are divided into slurry and additive liquid so as to become the polishing liquid May be. The slurry includes at least abrasive grains and a liquid medium, for example. The additive liquid includes, for example, at least the peptide compound, the branched polymer, and a liquid medium. It is preferable that the peptide compound, the branched polymer, an arbitrary additive, and a buffering agent are included in the additive liquid among the slurry and the additive liquid. The constituents of the polishing liquid may be stored as a polishing liquid set divided into three or more liquids.

  In the polishing liquid set, slurry and additive liquid are mixed immediately before polishing or at the time of polishing to prepare a polishing liquid. Further, the one-component polishing liquid may be stored as a polishing liquid storage liquid in which the content of the liquid medium is reduced, and may be diluted with the liquid medium during polishing. The multi-liquid type polishing liquid set may be stored as a slurry storage liquid and an additive liquid storage liquid with a reduced content of the liquid medium, and may be diluted with the liquid medium during polishing.

  In the case of a one-component polishing liquid, the polishing liquid is supplied onto the polishing surface plate by directly supplying the polishing liquid; supplying the polishing liquid storage liquid and the liquid medium through separate pipes. , A method of supplying these by mixing and mixing them; a method of supplying the polishing liquid stock solution and the liquid medium after mixing them in advance.

  When storing as a multi-liquid type polishing liquid set divided into slurry and additive liquid, the polishing rate can be adjusted by arbitrarily changing the composition of these liquids. In the case of polishing using a polishing liquid set, there are the following methods for supplying the polishing liquid onto the polishing surface plate. For example, a method in which slurry and additive liquid are fed through separate pipes, and these pipes are combined, mixed and supplied; a slurry storage liquid, an additive liquid storage liquid, and a liquid medium are fed through separate pipes. , A method in which these are merged and mixed; a method in which slurry and additive liquid are mixed and supplied in advance; a method in which slurry storage liquid, storage liquid for additive liquid, and liquid medium are mixed in advance and supplied Can be used. Further, it is possible to use a method of supplying the slurry and the additive liquid in the polishing liquid set onto the polishing surface plate, respectively. In this case, the surface to be polished is polished using a polishing liquid obtained by mixing the slurry and the additive liquid on the polishing surface plate.

  The polishing liquid set according to the present embodiment may be divided into a polishing liquid containing at least the essential component and an additive liquid containing at least an optional component such as an oxidizing agent (for example, hydrogen peroxide). . In this case, polishing is performed using a mixed liquid obtained by mixing the polishing liquid and the additive liquid (the mixed liquid also corresponds to the “polishing liquid”). Moreover, the polishing liquid set according to the present embodiment is a polishing liquid set divided into three or more liquids, a liquid containing at least a part of the essential components, a liquid containing at least the remainder of the essential components, and an optional component. The mode may be divided into the additive solution containing at least. Each liquid constituting the polishing liquid set may be stored as a storage liquid in which the content of the liquid medium is reduced.

<Polishing method of substrate>
The substrate polishing method according to the present embodiment may include a polishing step of polishing the surface to be polished of the substrate using the one-component polishing liquid, and the slurry and the additive liquid in the polishing liquid set are mixed. A polishing step of polishing the surface to be polished of the substrate using the polishing liquid obtained in this manner may be provided.

  In addition, the substrate polishing method according to the present embodiment may be a method for polishing a substrate having an insulating material and silicon nitride. For example, the one-part polishing liquid or the slurry and additive liquid in the polishing liquid set A polishing step of selectively polishing the insulating material with respect to silicon nitride may be provided using a polishing liquid obtained by mixing the above. In this case, the base may have, for example, a member containing an insulating material and a member containing silicon nitride. Note that “selectively polishing material A with respect to material B” means that the polishing rate of material A is higher than the polishing rate of material B under the same polishing conditions. More specifically, for example, the material A is polished at a polishing rate ratio of the polishing rate of the material A to the polishing rate of the material B of 30 or more.

  The substrate polishing method according to this embodiment may be a method for polishing a substrate having an insulating material and polysilicon. For example, the one-part polishing liquid, or the slurry and additive liquid in the polishing liquid set. And a polishing step of selectively polishing the insulating material with respect to polysilicon using a polishing liquid obtained by mixing the above and the like. In this case, the base may have, for example, a member containing an insulating material and a member containing polysilicon.

  In the polishing step, for example, the polishing liquid is supplied between the material to be polished and the polishing pad in a state where the material to be polished of the substrate having the material to be polished is pressed against the polishing pad (polishing cloth) of the polishing surface plate. The surface to be polished of the material to be polished is polished by relatively moving the substrate and the polishing surface plate. In the polishing step, for example, at least a part of the material to be polished is removed by polishing.

  Examples of the substrate to be polished include a substrate. For example, a material to be polished is formed on a substrate for manufacturing a semiconductor element (for example, a semiconductor substrate on which an STI pattern, a gate pattern, a wiring pattern, etc. are formed). A substrate is mentioned. Examples of materials to be polished include insulating materials such as silicon oxide; stopper materials such as polysilicon and silicon nitride. The material to be polished may be a single material or a plurality of materials. When a plurality of materials are exposed on the surface to be polished, they can be regarded as materials to be polished. The material to be polished may be in the form of a film, and may be a silicon oxide film, a polysilicon film, a silicon nitride film, or the like.

  A material to be polished (such as an insulating material such as silicon oxide) formed on such a substrate is polished with the polishing liquid, and an excess portion is removed to eliminate unevenness on the surface of the material to be polished, It can be a smooth surface over the entire surface of the abrasive material. The polishing liquid according to this embodiment is preferably used for polishing a surface to be polished containing silicon oxide.

  In this embodiment, an insulating material in a base body having an insulating material containing at least silicon oxide on the surface, a stopper (polishing stop layer) disposed under the insulating material, and a semiconductor substrate disposed under the stopper is polished. can do. The stopper material constituting the stopper is a material whose polishing rate is lower than that of the insulating material, and polysilicon, silicon nitride and the like are preferable. In such a base, since the polishing is stopped when the stopper is exposed, the insulating material can be prevented from being excessively polished, so that the flatness of the insulating material after polishing can be improved.

  Examples of a method for producing a material to be polished by the polishing liquid according to this embodiment include a low pressure CVD method, a quasi-atmospheric pressure CVD method, a plasma CVD method, and other CVD methods; a spin coating method in which a liquid material is applied to a rotating substrate Etc.

Silicon oxide can be obtained, for example, by thermally reacting monosilane (SiH ₄ ) and oxygen (O ₂ ) using a low pressure CVD method. Silicon oxide can be obtained, for example, by thermally reacting tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ) and ozone (O ₃ ) using a quasi-atmospheric pressure CVD method. As another example, silicon oxide can be similarly obtained by causing a plasma reaction between tetraethoxysilane and oxygen.

  Silicon oxide is obtained, for example, by applying a liquid raw material containing inorganic polysilazane, inorganic siloxane or the like on a substrate using a spin coating method and performing a thermosetting reaction in a furnace body or the like.

  Examples of the method for producing polysilicon include a low pressure CVD method in which monosilane is thermally reacted, a plasma CVD method in which monosilane is subjected to plasma reaction, and the like.

  As a method for producing silicon nitride, for example, a low pressure CVD method in which dichlorosilane and ammonia are thermally reacted, a plasma CVD method in which monosilane, ammonia and nitrogen are subjected to plasma reaction, and the like can be given. The silicon nitride obtained by the above method may contain elements other than silicon and nitrogen, such as carbon and hydrogen, in order to adjust the material.

  In order to stabilize materials such as silicon oxide, polysilicon, and silicon nitride obtained by the above method, heat treatment may be performed at a temperature of 200 to 1000 ° C. as necessary. Further, the silicon oxide obtained by the above method may contain a small amount of boron (B), phosphorus (P), carbon (C) or the like in order to improve the embedding property.

  Hereinafter, the polishing method according to this embodiment will be described by taking a polishing method of a semiconductor substrate on which an insulating material is formed as an example. In the polishing method according to the present embodiment, as a polishing apparatus, a general polishing apparatus having a holder capable of holding a substrate such as a semiconductor substrate having a surface to be polished and a polishing surface plate to which a polishing pad can be attached. Can be used. Each of the holder and the polishing surface plate is provided with a motor capable of changing the rotation speed. As the polishing apparatus, for example, a polishing apparatus manufactured by Ebara Manufacturing Co., Ltd .: F-REX300, or a polishing apparatus manufactured by APPLIED MATERIALS: Reflexion can be used.

  As the polishing pad, a general nonwoven fabric, foam, non-foam, or the like can be used. The material of the polishing pad is polyurethane, acrylic resin, polyester, acrylic-ester copolymer, polytetrafluoroethylene, polypropylene, polyethylene, poly-4-methylpentene, cellulose, cellulose ester, polyamide (for example, nylon (trade name)) And aramid), polyimide, polyimide amide, polysiloxane copolymer, oxirane compound, phenol resin, polystyrene, polycarbonate, epoxy resin and the like. As the material of the polishing pad, foamed polyurethane and non-foamed polyurethane are particularly preferable from the viewpoint of further excellent polishing speed and flatness. It is preferable that the polishing pad is grooved so that the polishing liquid accumulates.

Although there is no limitation on the polishing conditions, the rotation speed of the polishing platen is preferably 200 min ⁻¹ or less so that the semiconductor substrate does not pop out, and the polishing pressure (processing load) applied to the semiconductor substrate is such that polishing flaws occur. From the viewpoint of sufficiently suppressing, 100 kPa or less is preferable. During polishing, it is preferable to continuously supply the polishing liquid to the polishing pad with a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of a polishing pad is always covered with polishing liquid.

  The semiconductor substrate after the polishing is preferably washed well under running water to remove particles adhering to the substrate. For cleaning, dilute hydrofluoric acid or ammonia water may be used in addition to pure water, and a brush may be used in combination to increase cleaning efficiency. In addition, after cleaning, it is preferable to dry the semiconductor substrate after removing water droplets attached to the semiconductor substrate using a spin dryer or the like.

  The polishing liquid, the polishing liquid set, and the polishing method according to this embodiment can be suitably used for forming STI. In order to form the STI, the polishing rate ratio of the insulating material (for example, silicon oxide) to the stopper material (for example, silicon nitride) is preferably 10 or more. When the polishing rate ratio is less than 10, the polishing rate of the insulating material relative to the polishing rate of the stopper material is small, and it tends to be difficult to stop polishing at a predetermined position when forming the STI. On the other hand, when the polishing rate ratio is 10 or more, the polishing can be easily stopped, which is more suitable for the formation of STI. The polishing rate of the insulating material (for example, silicon oxide) is preferably 70 nm / min or more, more preferably 100 nm / min or more, and further preferably 130 nm / min or more. The polishing rate of the stopper material (for example, silicon nitride) is preferably 5 nm / min or less, more preferably 3 nm / min or less, and further preferably 2 nm / min or less.

  The polishing liquid, the polishing liquid set, and the polishing method according to this embodiment can also be used for polishing a premetal insulating material. As the premetal insulating material, in addition to silicon oxide, for example, phosphorus-silicate glass, boron-phosphorus-silicate glass is used, and silicon oxyfluoride, fluorinated amorphous carbon, and the like can also be used.

  The polishing liquid, the polishing liquid set, and the polishing method according to this embodiment can be applied to materials other than insulating materials such as silicon oxide. Such materials include high dielectric constant materials such as Hf-based, Ti-based, and Ta-based oxides; semiconductor materials such as silicon, amorphous silicon, SiC, SiGe, Ge, GaN, GaP, GaAs, and organic semiconductors; GeSbTe Inorganic conductive materials such as ITO; Polymer resins such as polyimides, polybenzoxazoles, acrylics, epoxies, and phenols.

  The polishing liquid, the polishing liquid set, and the polishing method according to the present embodiment are not only film-like objects to be polished, but also various types composed of glass, silicon, SiC, SiGe, Ge, GaN, GaP, GaAs, sapphire, plastic, or the like. It can also be applied to substrates.

  The polishing liquid, the polishing liquid set, and the polishing method according to the present embodiment are not only for manufacturing semiconductor elements, but also for image display devices such as TFTs and organic ELs; optical parts such as photomasks, lenses, prisms, optical fibers, and single crystal scintillators Optical elements such as optical switching elements and optical waveguides; light emitting elements such as solid lasers and blue laser LEDs; and magnetic storage devices such as magnetic disks and magnetic heads.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to this.

<Synthesis of hydroxides of tetravalent metal elements>
350 g of Ce (NH ₄ ) ₂ (NO ₃ ) ₆ 50% by mass aqueous solution (manufactured by Nippon Chemical Industry Co., Ltd., trade name: CAN50 liquid) was mixed with 7825 g of pure water to obtain a solution. Next, while stirring this solution, 750 g of an imidazole aqueous solution (10 mass% aqueous solution, 1.47 mol / L) was added dropwise at a mixing rate of 5 mL / min to obtain a precipitate containing cerium hydroxide. The synthesis of cerium hydroxide was performed at a temperature of 25 ° C. and a stirring speed of 400 min ⁻¹ . Stirring was carried out using a three-blade pitch paddle with a total blade length of 5 cm.

The obtained precipitate containing cerium hydroxide was centrifuged (4000 min ⁻¹ , 5 minutes) and then subjected to solid-liquid separation by removing the liquid phase by decantation. 10 g of particles obtained by solid-liquid separation and 990 g of water are mixed, and the particles are dispersed in water using an ultrasonic cleaner, and a cerium hydroxide slurry storage liquid (particle content: 1.0 mass) %) Was prepared.

<Measurement of average particle size>
It was 25 nm when the average particle diameter of the cerium hydroxide particle | grains in the stock solution for cerium hydroxide slurries was measured using the Beckman Coulter Co., Ltd. brand name: N5. The measuring method is as follows. First, about 1 mL of a measurement sample (aqueous dispersion) containing 1.0% by mass of cerium hydroxide particles was placed in a 1 cm square cell, and the cell was placed in N5. The refractive index of the measurement sample information of N5 software was set to 1.333, the viscosity was set to 0.887 mPa · s, the measurement was performed at 25 ° C., and the value displayed as the Unimodal Size Mean was read.

<Structural analysis of abrasive grains>
An appropriate amount of a cerium hydroxide slurry stock solution was collected, vacuum dried to isolate the abrasive grains, and then thoroughly washed with pure water to obtain a sample. When the obtained sample was measured by the FT-IR ATR method, a peak based on nitrate ion (NO ₃ ⁻ ) was observed in addition to a peak based on hydroxide ion (OH ⁻ ). Further, when XPS (N-XPS) measurement was performed on the sample, a peak based on NH ₄ ⁺ was not observed, and a peak based on nitrate ions was observed. From these results, it was confirmed that the abrasive grains contained in the cerium hydroxide slurry stock solution contained at least some particles having nitrate ions bonded to the cerium element. In addition, it was confirmed that the abrasive grains contained cerium hydroxide because they contained at least part of particles having hydroxide ions bonded to cerium element. From these results, it was confirmed that the hydroxide of cerium contains hydroxide ions bonded to the cerium element.

<Measurement of absorbance and light transmittance>
An appropriate amount of the cerium hydroxide slurry stock solution was collected and diluted with water so that the abrasive grain content was 0.0065% by mass (65 ppm) to obtain a measurement sample (aqueous dispersion). About 4 mL of this measurement sample was placed in a 1 cm square cell, and the cell was installed in a spectrophotometer (device name: U3310) manufactured by Hitachi, Ltd. Absorbance was measured in the wavelength range of 200 to 600 nm, and the absorbance to light having a wavelength of 290 nm and the absorbance to light having a wavelength of 450 to 600 nm were measured. Absorbance with respect to light having a wavelength of 290 nm was 1.192, and absorbance with respect to light having a wavelength of 450 to 600 nm was less than 0.010.

  About 4 mL of a cerium hydroxide slurry storage solution (particle content: 1.0 mass%) is placed in a 1 cm square cell, and the cell is placed in a spectrophotometer (device name: U3310) manufactured by Hitachi, Ltd. did. Absorbance was measured in the wavelength range of 200 to 600 nm, and the absorbance with respect to light with a wavelength of 400 nm and the light transmittance with respect to light with a wavelength of 500 nm were measured. Absorbance with respect to light with a wavelength of 400 nm was 2.25, and light transmittance with respect to light with a wavelength of 500 nm was 92% / cm.

<Preparation of polishing liquid for CMP>
Example 1
Glycyl-DL-phenylalanine [manufactured by Tokyo Chemical Industry Co., Ltd.] 2.0 mass%, branched polymer [manufactured by BYK-Chemie GmbH, product name: DISPERBYK-190, nonvolatile content: 40 mass%, acid value: 10 mgKOH / g, Weight average molecular weight: 23000] 0.5% by mass, polyoxyethylene bisphenol ether [manufactured by Nippon Emulsifier Co., Ltd., trade name: BA17-glycol, ethylene oxide 17 mol adduct] 5.0% by mass, polydiallyldimethylammonium chloride [ Senka Co., Ltd.] 0.02% by mass, 2-methylimidazole [pH adjuster] 0.08% by mass, acetic acid 0.05% by mass and water 92.35% by mass, 100 g of an additive stock solution, Mixing 850 g of water and 50 g of the cerium hydroxide slurry stock solution obtained above. To 0.05% by weight of abrasive grains containing cerium hydroxide, 0.2% by weight of glycyl-DL-phenylalanine, 0.05% by weight of branched polymer, and 0.5% by weight of polyoxyethylene bisphenol ether A polishing slurry for CMP having a pH of 6.0 and containing 0.002% by mass of polydiallyldimethylammonium chloride was prepared. The weight average molecular weight of the branched polymer was measured under the following conditions.

[Molecular weight measurement conditions]
Equipment used: ACQUITY APC system [manufactured by Waters]
Column: Waters ACQUITY APC XT 200 + Waters ACQUITY APC XT 45 + Waters ACQUITY APC XT 45 [trade name, manufactured by Waters, 3 in total]
Eluent: Tetrahydrofuran Column temperature: 45 ° C
Detector: ACQUITY Differential refractometer (RI) detector [manufactured by Waters]
RI temperature: 45 ° C
Data processing: Empower 3 [manufactured by Waters]
Injection volume: 10 μL
Standard materials: polystyrene, Shodex STANDARD SM-105 [manufactured by Showa Denko KK]

(Example 2)
Except having changed glycyl-DL-phenylalanine into DL-alanyl-DL-phenylalanine [manufactured by Tokyo Chemical Industry Co., Ltd.] in the same manner as in Example 1, 0.05% by mass of abrasive grains containing cerium hydroxide, PH 6 containing 0.2% by mass of DL-alanyl-DL-phenylalanine, 0.05% by mass of branched polymer, 0.5% by mass of polyoxyethylene bisphenol ether, and 0.002% by mass of polydiallyldimethylammonium chloride. 0.0 polishing slurry for CMP was prepared.

(Example 3)
An abrasive containing cerium hydroxide in the same manner as in Example 1 except that glycyl-DL-phenylalanine was changed to NL-α-aspartyl-L-phenylalanine-1-methyl [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.05% by mass of grains, 0.2% by mass of NL-α-aspartyl-L-phenylalanine-1-methyl, 0.05% by mass of branched polymer, and 0.5% by mass of polyoxyethylene bisphenol ether %, And a polishing slurry for CMP having a pH of 6.0 containing 0.002% by mass of polydiallyldimethylammonium chloride.

Example 4
Except not using polydiallyldimethylammonium chloride, it carries out similarly to Example 3, 0.05 mass% of abrasive grains containing a cerium hydroxide, NL-α-aspartyl-L-phenylalanine-1-methyl A polishing slurry for CMP having a pH of 6.0 containing 0.2% by mass, 0.05% by mass of branched polymer, and 0.5% by mass of polyoxyethylene bisphenol ether was prepared.

(Comparative Example 1)
Except not using glycyl-DL-phenylalanine, the same as in Example 1, 0.05% by weight of abrasive grains containing cerium hydroxide, 0.05% by weight of branched polymer, and polyoxyethylene bisphenol ether A polishing slurry for CMP having a pH of 6.0 containing 0.5% by mass and 0.002% by mass of polydiallyldimethylammonium chloride was prepared.

(Comparative Example 2)
Except for changing glycyl-DL-phenylalanine to glycine [manufactured by Tokyo Chemical Industry Co., Ltd.], in the same manner as in Example 1, 0.05% by mass of abrasive grains containing cerium hydroxide and 0.2% by mass of glycine %, A polishing slurry for CMP having a pH of 6.0 containing 0.05% by mass of branched polymer, 0.5% by mass of polyoxyethylene bisphenol ether and 0.002% by mass of polydiallyldimethylammonium chloride.

(Comparative Example 3)
Except that glycyl-DL-phenylalanine was changed to glycylglycine [manufactured by Tokyo Chemical Industry Co., Ltd.], in the same manner as in Example 1, 0.05% by mass of abrasive grains containing cerium hydroxide and glycylglycine were used. A polishing slurry for CMP having a pH of 6.0 containing 0.2% by mass, 0.05% by mass of branched polymer, 0.5% by mass of polyoxyethylene bisphenol ether, and 0.002% by mass of polydiallyldimethylammonium chloride. Prepared.

<Evaluation of polishing fluid properties>
(PH measurement)
The pH of the CMP polishing liquid was evaluated under the following conditions.
Measurement temperature: 25 ± 5 ° C
Measuring device: manufactured by Electrochemical Instrument Co., Ltd., model number PHL-40
Measurement method: Two-point calibration using a standard buffer (phthalate pH buffer, pH: 4.01 (25 ° C.); neutral phosphate pH buffer, pH: 6.86 (25 ° C.)) Thereafter, the electrode was placed in a polishing slurry for CMP, and the pH after being stabilized for 2 minutes or more was measured with the measuring device.

(Abrasive grain size measurement)
The average particle size (average secondary particle size) of the abrasive grains (abrasive grains containing cerium hydroxide) in the CMP polishing liquid was evaluated under the following conditions.
Measurement temperature: 25 ± 5 ° C
Measuring device: Beckman Coulter, product name: N5
Measuring method: About 1 mL of a stock solution of CMP polishing liquid was placed in a 1 cm square measuring cell, and the cell was placed in N5. Measurement was performed with the refractive index of the measurement sample information in N5 software set to 1.33 and the viscosity set to 0.887 mPa · s, and the value displayed as Unimodal Size Mean was read.

<CMP evaluation>
The substrate to be polished was polished under the following polishing conditions using the polishing liquids for CMP of Examples and Comparative Examples.

(CMP polishing conditions)
Polishing device: F-REX300 (manufactured by Ebara Corporation)
-Polishing liquid flow rate for CMP: 200 mL / min-Substrate to be polished: Blanket wafer and pattern wafer described below-Polishing pad: Foam polyurethane resin having closed cells (Rohm and Haas Japan Co., Ltd., model number IC1010)
Polishing pressure: 20 kPa (3.0 psi)
・ Number of rotations of substrate and polishing surface plate: (substrate) / (polishing surface plate) = 93/87 rpm
Polishing time (blanket wafer): 1 minute Polishing time (pattern wafer): Polishing was performed at the polishing time A until the silicon nitride film was exposed, and further polishing was performed at the same time as the polishing time A.
-Cleaning: After CMP treatment, cleaning with ultrasonic water was performed, followed by drying with a spin dryer.

(Blanket wafer)
As a blanket wafer without pattern (wafer without pattern), a silicon oxide film having a thickness of 1 μm is formed on the silicon substrate by plasma CVD, and a silicon nitride film having a thickness of 0.2 μm is formed on the silicon substrate. A substrate formed by a CVD method was used.

(Pattern wafer)
As a pattern wafer on which a simulated pattern was formed, a 764 wafer (trade name, diameter: 300 mm) manufactured by SEMATECH was used. In the patterned wafer, a silicon nitride film is stacked on a silicon substrate as a stopper film, and then a trench is formed in an exposure process to fill the silicon nitride film and the trench, and a silicon oxide film as an insulating film on the silicon substrate and the silicon nitride film. It was a wafer obtained by laminating (SiO ₂ film). The silicon oxide film was formed by the HDP (High Density Plasma) method.

  The pattern wafer has a portion where lines (convex portions) & spaces (concave portions) are 200 μm pitch and 100 μm pitch and the convex pattern density is 50%. The line & space is a simulated pattern having an active part masked with a silicon nitride film that is a convex part and a trench part in which grooves that are concave parts are formed. Yes. For example, “the line and space has a pitch of 100 μm” means that the total width of the line portion and the space portion is 100 μm. For example, “the line and space is 100 μm pitch and the convex pattern density is 50%” means a pattern in which convex widths 50 μm and concave widths 50 μm are alternately arranged.

  In the patterned wafer, the thickness of the silicon oxide film was 600 nm on both the silicon substrate and the silicon nitride film. Specifically, as shown in FIG. 3, the thickness of the silicon nitride film 2 on the silicon substrate 1 is 150 nm, the thickness of the convex portion of the silicon oxide film 3 is 600 nm, and the concave portion of the silicon oxide film 3 is formed. The thickness of the concave portion of the silicon oxide film 3 was 500 nm (trench depth 350 nm + silicon nitride film thickness 150 nm).

  In polishing evaluation of a patterned wafer, the wafer is polished using a known CMP polishing liquid that provides a self-stopping property (a characteristic that the polishing rate decreases when the remaining step of the simulated pattern decreases), and the remaining step is about 30 nm. The wafer in the state was used. Specifically, using a polishing liquid in which Hitachi Chemical Co., Ltd. HS-8005-D4, Hitachi Chemical Co., Ltd. HS-7303GP, and water were blended in a ratio of 2: 1.2: 6.8, A wafer in which the thickness of the silicon oxide film on the convex portion in the portion having a convex pattern density of 50% was polished to 50 nm at a pitch of 200 μm was used.

<Polished product evaluation>
[Blanket wafer polishing speed]
With respect to the substrate to be polished polished and cleaned under the above conditions, the polishing rate of the film to be polished (silicon nitride film and silicon oxide film) (silicon nitride film polishing rate: SiNRR and silicon oxide film polishing rate: SiO ₂ RR) Was obtained from the following equation. In addition, the film thickness difference of the to-be-polished film before and behind the polishing was determined using an optical interference type film thickness measuring apparatus (manufactured by Filmetrics, trade name: F80). Further, the polishing selectivity (SiO ₂ RR / SiNRR) was calculated using the polishing rate of the film to be polished.
(Polishing rate: RR) = (Thickness difference of the film to be polished before and after polishing (nm)) / (Polishing time (min))

[Pattern wafer evaluation]
Residual step amount (dishing) by measuring the remaining film thickness of the silicon nitride film on the convex portions of the 200 μm pitch and 100 μm pitch of the patterned wafer polished and cleaned under the above conditions and the residual film thickness of the silicon oxide film in the concave portions (dishing) Was obtained from the following equation. In addition, the film thickness of each to-be-polished film | membrane before and behind grinding | polishing was calculated | required using the optical interference type film thickness measuring apparatus (Nanometrics company make, brand name: Nanospec AFT-5100).
Residual step (dishing) = (350 nm + residual film thickness of silicon nitride film (nm)) − (residual film thickness of recessed silicon oxide film (nm))

  Table 1 shows the measurement results obtained in the examples and comparative examples.

  Hereinafter, the results shown in Table 1 will be described in detail.

In Example 1, the SiO ₂ RR was 205 nm / min, the SiNRR was 2 nm / min, and the polishing rate ratio SiO ₂ RR / SiNRR was 103. In the pattern wafer evaluation, the remaining steps when the silicon nitride film is exposed are 15 nm (200 μm pitch) and 8 nm (100 μm pitch), respectively, and the remaining steps are 20 nm and 15 nm, respectively, even if they are further etched for 15 seconds. The example showed that dishing was suppressed.

In Example 2, the SiO ₂ RR was 202 nm / min, the SiNRR was 1 nm / min, and the polishing rate ratio SiO ₂ RR / SiNRR was 202. In the pattern wafer evaluation, the remaining steps when the silicon nitride film is exposed are 17 nm (200 μm pitch) and 7 nm (100 μm pitch), respectively, and the remaining steps are 25 nm and 13 nm, respectively, even if they are further etched for 15 seconds. The example showed that dishing was suppressed.

In Example 3, SiO ₂ RR was 197 nm / min, SiNRR was 1 nm / min, and polishing rate ratio SiO ₂ RR / SiNRR was 197. In the pattern wafer evaluation, the remaining steps when the silicon nitride film is exposed are 12 nm (200 μm pitch) and 5 nm (100 μm pitch), respectively. The example showed that dishing was suppressed.

In Example 4, the SiO ₂ RR was 158 nm / min, the SiNRR was 3 nm / min, and the polishing rate ratio SiO ₂ RR / SiNRR was 53. In the pattern wafer evaluation, the remaining steps when the silicon nitride film is exposed are 11 nm (200 μm pitch) and 5 nm (100 μm pitch), respectively, and the remaining steps are 17 nm and 11 nm, respectively, even if they are further etched for 19 seconds. The example showed that dishing was suppressed.

In Comparative Example 1, the SiO ₂ RR was 210 nm / min, the SiNRR was 8 nm / min, and the polishing rate ratio SiO ₂ RR / SiNRR was 26. In the pattern wafer evaluation, the remaining steps at the time when the silicon nitride film was exposed were 22 nm (200 μm pitch) and 14 nm (100 μm pitch), respectively, and when remaining for 14 seconds, the remaining steps were 31 nm and 23 nm, respectively.

In Comparative Example 2, the SiO ₂ RR was 240 nm / min, the SiNRR was 10 nm / min, and the polishing rate ratio SiO ₂ RR / SiNRR was 24. In the pattern wafer evaluation, the remaining steps when the silicon nitride film was exposed were 27 nm (200 μm pitch) and 18 nm (100 μm pitch), respectively, and when remaining for 13 seconds, the remaining steps were 39 nm and 27 nm, respectively.

In Comparative Example 3, the SiO ₂ RR was 228 nm / min, the SiNRR was 8 nm / min, and the polishing rate ratio SiO ₂ RR / SiNRR was 29. In the pattern wafer evaluation, the remaining steps at the time when the silicon nitride film was exposed were 24 nm (200 μm pitch) and 15 nm (100 μm pitch), respectively, and when remaining for 13 seconds, the remaining steps were 33 nm and 24 nm, respectively.

  DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Silicon nitride film, 3 ... Silicon oxide film.

Claims (18)

A liquid medium, abrasive grains, a peptide compound having a phenylalanine skeleton, and a polymer,
The polymer has a first molecular chain having a functional group directly bonded thereto, and a second molecular chain branched from the first molecular chain,
A polishing liquid, wherein the functional group is at least one selected from the group consisting of a carboxyl group, a carboxylate group, a hydroxyl group, a sulfo group, and a sulfonate group.   From the structural unit derived from styrene, the structural unit derived from olefin, the structural unit derived from acrylic acid, the structural unit derived from methacrylic acid, the structural unit derived from maleic acid, and the structural unit derived from vinyl acetate. The polishing liquid according to claim 1, comprising at least one selected from the group consisting of:   The polishing liquid according to claim 1 or 2, wherein the first molecular chain includes at least one selected from the group consisting of a polyester chain, a polyurethane chain, and a polyamide chain.   The polishing liquid according to claim 1, wherein the second molecular chain contains at least one selected from the group consisting of a hydrophilic molecular chain and a hydrophobic molecular chain.   The polishing liquid according to claim 1, wherein the second molecular chain includes at least one selected from the group consisting of a polyether chain, a polyvinyl alcohol chain, and a polyvinylpyrrolidone chain.   The second molecular chain is a structural unit derived from styrene, a structural unit derived from olefin, a structural unit derived from acrylic acid, a structural unit derived from methacrylic acid, a structural unit derived from maleic acid, a structural unit derived from vinyl acetate, or a polyester chain. The polishing liquid according to claim 1, comprising at least one selected from the group consisting of polyurethane chains and polyamide chains.   The polishing liquid according to claim 1, wherein the abrasive grains include at least one selected from the group consisting of ceria, silica, alumina, zirconia, yttria, and a hydroxide of a tetravalent metal element. .   The polishing liquid according to claim 7, wherein the abrasive grains contain a hydroxide of a tetravalent metal element.   9. The polishing liquid according to claim 7, wherein the tetravalent metal element hydroxide is at least one selected from the group consisting of rare earth metal hydroxides and zirconium hydroxides.   The polishing liquid according to claim 1, wherein the content of the polymer is 0.001% by mass or more and 0.5% by mass or less based on the total mass of the polishing liquid.   The polishing liquid as described in any one of Claims 1-10 used in order to grind | polish the to-be-polished surface containing a silicon oxide.   The constituents of the polishing liquid according to any one of claims 1 to 11 are stored separately in a first liquid and a second liquid, and the first liquid includes the abrasive grains and a liquid medium. The polishing liquid set, wherein the second liquid includes the peptide compound, the polymer, and a liquid medium.   A method for polishing a substrate, comprising a step of polishing a surface to be polished of the substrate using the polishing liquid according to claim 1.   A polishing method for a substrate, comprising a step of polishing a surface to be polished of a substrate using a polishing liquid obtained by mixing the first liquid and the second liquid in the polishing liquid set according to claim 12. A method for polishing a substrate comprising an insulating material and silicon nitride,
A method for polishing a substrate, comprising: a step of selectively polishing the insulating material with respect to the silicon nitride using the polishing liquid according to claim 1. A method for polishing a substrate comprising an insulating material and silicon nitride,
A step of selectively polishing the insulating material with respect to the silicon nitride using a polishing liquid obtained by mixing the first liquid and the second liquid in the polishing liquid set according to claim 12. A method for polishing a substrate. A method for polishing a substrate comprising an insulating material and polysilicon,
A method for polishing a substrate, comprising: a step of selectively polishing the insulating material with respect to the polysilicon using the polishing liquid according to claim 1. A method for polishing a substrate comprising an insulating material and polysilicon,
A step of selectively polishing the insulating material with respect to the polysilicon using a polishing liquid obtained by mixing the first liquid and the second liquid in the polishing liquid set according to claim 12. A method for polishing a substrate.

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