WO2015052988A1

WO2015052988A1 - Polishing agent, polishing agent set and method for polishing base

Info

Publication number: WO2015052988A1
Application number: PCT/JP2014/071232
Authority: WO
Inventors: 友洋岩野; 知里吉川; 利明阿久津; 久貴南
Original assignee: 日立化成株式会社
Priority date: 2013-10-10
Filing date: 2014-08-11
Publication date: 2015-04-16
Also published as: TW201518489A

Abstract

A polishing agent which contains water, abrasive grains containing a hydroxide of a tetravalent metal element, a polymerization product of α-glucose and a cationic polymer, and wherein the polymerization product of α-glucose has a weight average molecular weight of 20.0 × 10³ or less.

Description

Abrasive, abrasive set, and substrate polishing method

The present invention relates to an abrasive, an abrasive set, and a method for polishing a substrate. In particular, the present invention relates to a polishing agent, a polishing agent set, and a substrate polishing method used in a substrate surface flattening step, which is a semiconductor element manufacturing technique. More particularly, the present invention relates to a polishing agent, a polishing agent set, and a substrate polishing method used in a flattening process of a shallow trench isolation (STI) insulating material, a premetal insulating material, an interlayer insulating material, and the like.

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 abrasive is a silica-based abrasive containing silica (silicon oxide) particles such as fumed silica and colloidal silica as abrasive grains. Silica-based abrasives are characterized by high versatility, and a wide variety of materials can be polished regardless of insulating materials and conductive materials by appropriately selecting the abrasive content, pH, additives, and the like.

On the other hand, there is an increasing demand for abrasives containing cerium compound particles as abrasive grains mainly for insulating materials such as silicon oxide. For example, a cerium oxide-based abrasive 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 abrasive (see, for example, Patent Documents 1 and 2 below). .

By the way, in recent years, in the manufacturing process of semiconductor elements, 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 abrasive, 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, an abrasive using a hydroxide particle of a tetravalent metal element has 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, Patent Document 8 listed below uses an abrasive containing hydroxide particles of a tetravalent metal element and at least one of a cationic polymer and a polysaccharide, using silicon nitride as a stopper material. Polishing the insulating material is disclosed. Further, in Patent Document 9 below, an insulating material is polished using polysilicon as a stopper material by using an abrasive containing hydroxide particles of a tetravalent metal element and polyvinyl alcohol having a saponification degree of 95 mol% or less. Is disclosed.

JP-A-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

In recent years, in a CMP process or the like for forming an STI, in order to improve flatness and to suppress erosion (overpolishing of the stopper material), the polishing selectivity of the insulating material with respect to the stopper material is further increased. There is a need.

The present invention is intended to solve these problems, and an object thereof is to provide an abrasive, an abrasive set, and a substrate polishing method that can improve the polishing selectivity of an insulating material with respect to a stopper material. .

On the other hand, the present inventor uses a combination of abrasive grains containing a hydroxide of a tetravalent metal element, an α-glucose polymer having a specific weight average molecular weight, and a cationic polymer to insulate the stopper material. It has been found that the polishing selectivity of the material is further increased as compared with the prior art.

The abrasive according to the present invention contains water, abrasive grains containing a hydroxide of a tetravalent metal element, an α-glucose polymer, and a cationic polymer, and the weight of the α-glucose polymer The average molecular weight is 20.0 × 10 ³ or less.

Here, “weight average molecular weight” is defined as the weight average molecular weight determined by gel permeation chromatography (GPC) analysis.

The polishing agent according to the present invention can improve the polishing selectivity of the insulating material with respect to the stopper material.

By the way, as the stopper material, silicon nitride has been used for many years, but in recent years, processes using polysilicon have been increasing. In this case, it is necessary to suppress the polishing rate of polysilicon from the viewpoint of increasing the polishing selectivity of the insulating material with respect to polysilicon. However, conventional abrasives do not have sufficient polishing selectivity for insulating materials relative to both silicon nitride and polysilicon, and there is room for improvement.

On the other hand, according to the abrasive according to the present invention, the polishing selectivity of the insulating material with respect to the stopper material can be improved regardless of whether silicon nitride or polysilicon is used as the stopper material.

Further, according to the polishing agent according to the present invention, in the CMP technology for flattening the shallow trench isolation insulating material, the premetal insulating material, the interlayer insulating material, etc., the insulating material can be reduced with low polishing scratches while highly flattening the insulating material. It can also be polished.

Incidentally, dishing may occur in the CMP process or the like for forming STI conventionally. Dishing is a phenomenon in which an insulating material embedded in a recess is excessively removed, and a part of the surface to be polished is recessed like a dish. Therefore, in order to improve flatness, it is necessary to suppress the progress of dishing. On the other hand, the present inventor uses a combination of an abrasive containing a hydroxide of a tetravalent metal element, a specific α-glucose polymer, a cationic polymer, and an amino group-containing sulfonic acid compound as a stopper. It has been found that the polishing selectivity of the insulating material with respect to the material is further enhanced as compared with the conventional material and the progress of dishing can be suppressed.

The abrasive according to the present invention may further include an amino group-containing sulfonic acid compound, and the degree of polymerization of α-glucose in the α-glucose polymer may be 3 or more. In this case, the polishing selectivity of the insulating material with respect to the stopper material can be improved and the progress of dishing can be suppressed. Further, when a substrate having irregularities is polished, the surface to be polished can be flattened by suppressing the progress of dishing while maintaining the polishing selectivity of the insulating material with respect to the stopper material.

The α-glucose polymer preferably has at least one selected from the group consisting of a structural unit represented by the following formula (IA) and a structural unit represented by the following formula (IB). . Thereby, the polishing selectivity of the insulating material with respect to the stopper material can be further enhanced.

The tetravalent metal element hydroxide preferably contains a cerium hydroxide. Thereby, generation | occurrence | production of the grinding | polishing damage | wound in a to-be-polished surface can be suppressed, further improving the grinding | polishing selectivity of the insulating material with respect to a stopper material.

The pH of the abrasive according to the present invention is preferably 3.0 or more and 7.0 or less. Thereby, the insulating material can be polished at a suitable polishing rate, and the polishing selectivity of the insulating material to the stopper material can be further increased.

One embodiment of the present invention relates to the use of the abrasive for polishing a surface to be polished containing silicon oxide. That is, one embodiment of the abrasive according to the present invention is preferably used for polishing a surface to be polished containing silicon oxide.

In the abrasive set according to the present invention, the constituents of the abrasive are stored separately in a first liquid and a second liquid, the first liquid contains abrasive grains and water, and the second liquid is α. -Contains glucose polymer, cationic polymer and water. According to the abrasive | polishing agent set which concerns on this invention, the said effect similar to the abrasive | polishing agent which concerns on this invention can be acquired. The second liquid may contain an amino group-containing sulfonic acid compound.

The method for polishing a substrate according to the present invention may comprise a step of polishing the surface to be polished of the substrate using the abrasive. According to such a method for polishing a substrate, the same effects as those of the abrasive according to the present invention can be obtained.

The substrate polishing method according to the present invention includes a step of polishing a surface to be polished of the substrate using an abrasive obtained by mixing the first liquid and the second liquid in the abrasive set. May be. According to such a method for polishing a substrate, the same effects as those of the abrasive according to the present invention can be obtained.

According to the present invention, it is possible to provide a polishing agent, a polishing agent set and a substrate polishing method capable of improving the polishing selectivity of the insulating material with respect to the stopper material. According to one embodiment of the present invention, it is possible to provide a polishing agent, a polishing agent set, and a substrate polishing method capable of improving the polishing selectivity of an insulating material with respect to a stopper material and suppressing the progress of dishing.

According to the present invention, the polishing selectivity of the insulating material with respect to the stopper material can be improved in the polishing of the insulating material using the stopper. According to one embodiment of the present invention, in polishing of an insulating material using a stopper, the polishing selectivity of the insulating material with respect to the stopper material can be improved and the progress of dishing can be suppressed. In addition, according to the present invention, in CMP technology for flattening an STI insulating material, a pre-metal insulating material, an interlayer insulating material, etc., when the insulating material is polished using a stopper, the polishing selectivity of the insulating material with respect to the stopper material is improved. Can be made. According to one embodiment of the present invention, in CMP technology for planarizing an STI insulating material, a premetal insulating material, an interlayer insulating material, etc., when polishing an insulating material using a stopper, the polishing selectivity of the insulating material with respect to the stopper material is increased. It is possible to improve and suppress the progress of dishing.

According to the present invention, it is possible to provide use of an abrasive or an abrasive set for polishing an insulating material using a stopper. In addition, according to the present invention, it is possible to provide the use of an abrasive or a set of abrasives for polishing STI insulating material, premetal insulating material, interlayer insulating material and the like using a stopper. Furthermore, according to the present invention, it is possible to provide use of an abrasive or an abrasive set for polishing an insulating material using a stopper containing silicon nitride or polysilicon.

Hereinafter, an abrasive, an abrasive set, and a method for polishing a substrate using the abrasive or the abrasive set according to an embodiment of the present invention will be described in detail.

<Definition>
In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended action of the process is achieved even when it cannot be clearly distinguished from other processes. It is.

In this specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.

In this specification, “polishing rate” means a rate at which material is removed per unit time (removal rate = removal rate).

In the present specification, the phrase “this embodiment” includes the first embodiment and the second embodiment.

<Abrasive>
The abrasive | polishing agent which concerns on this embodiment is a composition which touches a to-be-polished surface at the time of grinding | polishing, for example, is an abrasive | polishing agent for CMP. Specifically, the abrasive according to the first embodiment contains at least water, abrasive grains containing a hydroxide of a tetravalent metal element, an α-glucose polymer, and a cationic polymer. The abrasive according to the second embodiment includes water, abrasive grains containing a hydroxide of a tetravalent metal element, an α-glucose polymer having a degree of polymerization of α-glucose of 3 or more, a cationic polymer, And at least an amino group-containing sulfonic acid compound. The essential components and components that can be optionally added are described below.

(Abrasive grains)
The abrasive | polishing agent which concerns on this embodiment contains the abrasive grain containing the hydroxide of a tetravalent metal element. The “tetravalent metal element hydroxide” is a compound containing a tetravalent metal (M ⁴⁺ ) and at least one hydroxide ion (OH ⁻ ). The hydroxide of the tetravalent metal element may contain an anion other than the hydroxide ion (for example, nitrate ion NO ₃ ⁻ , sulfate ion SO ₄ ²⁻ ). For example, a hydroxide of a tetravalent metal element may contain an anion (for example, nitrate ion NO ₃ ⁻ , sulfate ion SO ₄ ²⁻ ) bonded to the tetravalent metal element.

The abrasive grains containing a hydroxide of the tetravalent metal element are more reactive with an insulating material (for example, silicon oxide) than conventional abrasive grains made of silica or ceria, and the insulating material can be removed at a high polishing rate. Can be polished. In the abrasive according to the present embodiment, examples of other abrasive grains that can be used in combination with the abrasive grains containing a hydroxide of a tetravalent metal element include silica particles, alumina particles, and ceria particles. In addition, as abrasive grains containing a tetravalent metal element hydroxide, composite particles of tetravalent metal element hydroxide particles and silica particles can be used.

The lower limit of the content of the tetravalent metal element hydroxide in the abrasive is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more based on the total mass of the abrasive grains. 98 mass% or more is especially preferable, and 99 mass% or more is very preferable. The abrasive grains are composed of hydroxide particles of the tetravalent metal element from the viewpoint of easy preparation of an abrasive and further excellent polishing properties (substantially 100% by mass of the abrasive grains is the tetravalent metal). Elemental hydroxide particles).

Tetravalent metal element hydroxides are rare earth element hydroxides and zirconium hydroxides from the viewpoint of suppressing the generation of polishing scratches on the surface to be polished while further improving the polishing selectivity of the insulating material with respect to the stopper material. It is preferable to include at least one selected from the group consisting of The tetravalent metal element is preferably a rare earth element from the viewpoint of further improving the polishing rate of the insulating material. Examples of rare earth elements that can be tetravalent include lanthanoids such as cerium, praseodymium, and terbium, and cerium is more preferable from the viewpoint of easy availability and excellent polishing rate. A rare earth element hydroxide and a zirconium hydroxide may be used in combination, and two or more rare earth elements may be selected and used.

As a method for producing abrasive grains containing a hydroxide of a tetravalent metal element, a technique of mixing a salt containing a tetravalent metal element and an alkali solution can be used. This method is described in, for example, “Science of rare earths” [edited by Adiya Ginya, Kagaku Dojin, 1999], pages 304-305. A method for producing abrasive grains containing a hydroxide of a tetravalent metal element that is most suitable for the abrasive according to this embodiment is described in Patent Document 7. The descriptions of these documents are incorporated herein by reference.

As the salt containing a tetravalent metal element, a conventionally known salt can be used without particular limitation, and M (SO ₄ ) ₂ , M (NH ₄ ) ₂ (NO ₃ ) ₆ , M (NH ₄ ) ₄ (SO ₄ ) ₄ (M represents a rare earth element), Zr (SO ₄ ) ₂ .4H ₂ O, and the like. M is preferably chemically active cerium (Ce).

As the alkali solution, a conventionally known one can be used without particular limitation. Basic compounds in the alkaline solution include organic bases such as imidazole, tetramethylammonium hydroxide (TMAH), guanidine, triethylamine, pyridine, piperidine, pyrrolidine, chitosan; ammonia, potassium hydroxide, sodium hydroxide, calcium hydroxide. Inorganic bases such as Among these, from the viewpoint of further improving the polishing rate of the insulating material, at least one selected from the group consisting of ammonia and imidazole is preferable, and imidazole is more preferable. Abrasive grains containing a hydroxide of a tetravalent metal element synthesized by the above method can be washed to remove metal impurities. As a method for cleaning the abrasive grains, a method of repeating solid-liquid separation several times by centrifugation or the like can be used. In addition, the abrasive grains can be washed in steps such as centrifugation, dialysis, ultrafiltration, and ion removal using an ion exchange resin.

When the abrasive grains obtained above are aggregated, it is preferable to disperse them 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 can be used in addition to the dispersion treatment using a normal stirrer. Regarding the dispersion method and the particle size control method, for example, the method described in Chapter 3 “Latest Development Trends and Selection Criteria of Various Dispersers” in “Dispersion Technology Complete Collection” [Information Organization, July 2005] Can be used. Further, the water content of the tetravalent metal element can also be reduced by reducing the electrical conductivity (for example, 500 mS / m or less) of the dispersion containing abrasive grains containing a hydroxide of the tetravalent metal element by performing the above-described cleaning treatment. The dispersibility of the abrasive grains containing the oxide can be increased. Therefore, the cleaning process may be applied as a dispersion process, and the cleaning process and the dispersion process may be used in combination.

The lower limit of the average grain size of the abrasive grains is preferably 1 nm or more, more preferably 2 nm or more, and further preferably 3 nm or more from the viewpoint of obtaining a more suitable polishing rate for the insulating material. The upper limit of the average grain size of the abrasive grains is preferably 300 nm or less, more preferably 250 nm or less, and even more preferably 200 nm or less, from the viewpoint of further suppressing scratches on the surface to be polished. 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 diameter of the abrasive grains can be measured, for example, by a photon correlation method for a slurry or a slurry in a polishing agent set described later. Specifically, the average particle size of the abrasive grains can be measured by, for example, device name: Zetasizer 3000HS manufactured by Malvern Instruments, device name: N5 manufactured by Beckman Coulter, and the like. The measuring method using N5 can be performed as follows. Specifically, for example, an aqueous dispersion in which the content of abrasive grains is adjusted to 0.2% by mass is prepared, and this aqueous dispersion is about 4 mL (L is “liter” in a 1 cm square cell. ) Put the cell in the device. The value obtained by setting the refractive index of the dispersion medium to 1.33, the viscosity to 0.887 mPa · s, and measuring at 25 ° C. can be adopted as the average particle diameter of the abrasive grains.

The lower limit of the content of the abrasive grains is preferably 0.01% by mass or more and more preferably 0.02% by mass or more based on the total mass of the abrasive from the viewpoint of obtaining a more suitable polishing rate for the insulating material. The upper limit of the content of the abrasive is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less, based on the total mass of the abrasive, from the viewpoint of increasing the storage stability of the abrasive. Preferably, 5 mass% or less is particularly preferable, 1 mass% or less is very preferable, and 0.5 mass% or less is very preferable. From the above viewpoint, the content of the abrasive grains is more preferably 0.01% by mass or more and 20% by mass or less based on the total mass of the abrasive.

(Additive)
The abrasive | polishing agent which concerns on this embodiment contains an additive. Here, the “additive” refers to a polishing agent other than water and abrasive grains in order to adjust polishing characteristics such as polishing rate and polishing selectivity; abrasive characteristics such as abrasive dispersibility and storage stability. Refers to the substance contained.

[First additive: α-glucose polymer]
The abrasive according to this embodiment contains an α-glucose polymer as the first additive. In the present specification, “α-glucose polymer” is defined as a polymer (for example, sugar) having a degree of polymerization of α-glucose of 2 or more unless otherwise specified. In the second embodiment, a polymer (for example, sugar) having a degree of polymerization of α-glucose of 3 or more is used. The first additive has an effect of suppressing an excessive increase in the polishing rate of the stopper material (for example, silicon nitride and polysilicon). Regarding the reason why this effect is obtained, it is presumed that the first additive covers the stopper, thereby suppressing the progress of polishing by the abrasive grains and suppressing the polishing rate from becoming excessively high.

Examples of α-glucose polymer include amylose; amylopectin; dextran; dextrin; maltodextrin; cyclodextrins such as α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin; maltose, isomaltose, maltotriose, stachyose, etc. Examples include oligosaccharides. The α-glucose polymer used in the second embodiment includes amylose; amylopectin; dextran; dextrin; maltodextrin; cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin; maltotriose, stachyose And oligosaccharides. The DE value of the α-glucose polymer (for example, the value according to the “LANE-EYNON method”) is preferably 13 to 50 from the viewpoint of further enhancing the polishing selectivity of the insulating material with respect to the stopper material.

As the above dextrin, dextrin having an aldehyde group at the end of the decomposition product obtained by decomposition of starch (referred to as “general dextrin” for distinction from other dextrins); difficult to be partially decomposed in the process of starch decomposition Examples include indigestible dextrin collected by purifying the product; reduced dextrin in which the aldehyde end is reduced by hydrogenation and changed to a hydroxyl group. Any of these compounds can be used as the dextrin.

As the α-glucose polymer, the “NSD” series manufactured by Sanei Saccharification Co., Ltd .; “Sun Mart-S”, “Sandeck” series manufactured by Sanwa Starch Co., Ltd .; “H-PDX”, “Max” manufactured by Matsutani Chemical 1000 ”,“ TK-16 ”,“ Fiber Sol 2 ”,“ Fiber Sol 2H ”and the like. The α-glucose polymer used in the second embodiment includes “NSD” series manufactured by Sanei Saccharification Co., Ltd .; “Sandek” series manufactured by Sanwa Starch Co., Ltd .; “H-PDX” manufactured by Matsutani Chemical Co. “Max 1000”, “TK-16”, “Fiber Sol 2”, “Fiber Sol 2H” and the like.

As the α-glucose polymer, from the viewpoint of effectively obtaining an effect of suppressing an excessive increase in the polishing rate of the stopper material, the structural unit represented by the following formula (IA) and the following formula ( It is preferable to have at least one selected from the group consisting of structural units represented by IB), more preferably at least one selected from the group consisting of dextrin and maltose (dextrin is more preferable in the second embodiment) ). In the case of including both the structural unit represented by the formula (IA) and the structural unit represented by the formula (IB), the arrangement thereof is not limited and may be regular or random. The α-glucose polymer is preferably at least one selected from the group consisting of dextrin and maltose from the viewpoint of excellent versatility (dextrin is more preferred in the second embodiment).

The α-glucose polymer preferably has at least one structural unit represented by the following formulas (II) to (VII), and more preferably has a structural unit represented by the formula (III). Thereby, the polishing selectivity of the insulating material with respect to the stopper material can be further enhanced.

In the first embodiment, the lower limit of the degree of polymerization of α-glucose is 2 or more, preferably 3 or more, and more preferably 5 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 degree of polymerization of α-glucose is preferably 120 or less, more preferably 90 or less, and even more preferably 60 or less, from the viewpoint that a good polishing rate of the insulating material can be easily obtained.

In the second embodiment, the lower limit of the polymerization degree of α-glucose is 3 or more, preferably 5 or more, more preferably 7 or more from the viewpoint of further enhancing the polishing selectivity of the insulating material with respect to the stopper material and suppressing the progress of dishing. More preferred is 10 or more. The upper limit of the degree of polymerization of α-glucose is preferably 120 or less, more preferably 90 or less, and even more preferably 60 or less, from the viewpoint that a good polishing rate of the insulating material can be easily obtained.

In the present specification, the “degree of polymerization of α-glucose” is defined as the number of structural units derived from α-glucose in one molecule. For example, the formula (IA) and the formula (I— B) is the total number of structural units represented by the formulas (II) to (VII) in one molecule.

In the abrasive according to this embodiment, the α-glucose polymer can be used alone or in combination of two or more for the purpose of adjusting polishing characteristics such as polishing selectivity.

The upper limit of the weight average molecular weight of the first additive is 20.0 × 10 ³ from the viewpoint of obtaining a good polishing rate of the insulating material (for example, silicon oxide) and improving the polishing selectivity of the insulating material with respect to the stopper material. It is as follows. The upper limit of the weight average molecular weight of the first additive is 20.0 × from the viewpoint of obtaining a better polishing rate of the insulating material (for example, silicon oxide) and further improving the polishing selectivity of the insulating material with respect to the stopper material. is preferably less than 10 ^3, more preferably 18.0 × 10 ³ or less, more preferably 15.0 × 10 ³ or less, particularly preferably 12.0 × 10 ³ or less, very preferably 10.0 × 10 ³ or less. The lower limit of the weight average molecular weight of the first additive in the first embodiment is preferably 250 or more, more preferably 350 or more, still more preferably 500 or more, from the viewpoint of further improving polishing selectivity and flatness. 0 × 10 ³ or more is particularly preferable, and 1.5 × 10 ³ or more is extremely preferable. From the above viewpoint, the weight average molecular weight of the first additive in the first embodiment is more preferably 250 or more and 20.0 × 10 ³ or less. From the viewpoint of further improving polishing selectivity and flatness, the lower limit of the weight average molecular weight of the first additive in the second embodiment is preferably 350 or more, more preferably 500 or more, still more preferably 800 or more. 0 × 10 ³ or more is particularly preferable, and 1.5 × 10 ³ or more is extremely preferable. From the above viewpoint, the weight average molecular weight of the first additive in the second embodiment is more preferably 350 or more and 20.0 × 10 ³ or less. 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.

(conditions)
Equipment used: LC-20AD (manufactured by Shimadzu Corporation)
Column: Gelpack GL-W540 + 550
Eluent: 0.1M NaCl aqueous solution Measurement temperature: 40 ° C
Column size: 10.7 mmI. D. × 300mm
Flow rate: 1.0 mL / min
Sample concentration: 0.2% by mass
Detector: RID-10A (manufactured by Shimadzu Corporation)

The lower limit of the content of the first additive is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, based on the total mass of the abrasive, from the viewpoint of further improving polishing selectivity and flatness. Preferably, 0.3% by mass or more is more preferable, and 0.5% by mass or more is particularly preferable. The upper limit of the content of the first additive is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, based on the total mass of the abrasive, from the viewpoint of obtaining an appropriate polishing rate of the insulating material. 2.0 mass% or less is still more preferable. From the above viewpoint, the content of the first additive is more preferably 0.01% by mass or more and 5.0% by mass or less based on the total mass of the abrasive. In addition, when using a some compound as a 1st additive, it is preferable that the sum total of content of each compound satisfy | fills the said range.

[Second additive: cationic polymer]
The abrasive | polishing agent which concerns on this embodiment contains a cationic polymer as a 2nd additive other than said 1st additive. The “cationic polymer” is a polymer having a cationic group or a group that can be ionized into a cationic group in a main chain or a side chain. The cationic polymer has an effect of suppressing an excessive increase in the polishing rate of the stopper material (for example, silicon nitride and polysilicon) when used in combination with the first additive. Also, there is an effect of increasing the polishing rate of the insulating material (for example, silicon oxide) without deteriorating the flatness. When the cationic polymer interacts with the first additive, the polishing rate of the stopper material can be suppressed, and the first additive excessively covers the insulating material to reduce the polishing rate of the insulating material. It is considered that the polishing rate of the insulating material can be improved by suppressing this. In addition, the cationic polymer interacts with the first additive so that the first additive appropriately coats the insulating material, thereby improving the polishing rate of the convex portion of the insulating material and insulating. In order to suppress the polishing rate of the concave portions of the material, it is considered that high flatness can be maintained.

The cationic polymer is at least one selected from the group consisting of an allylamine polymer, a diallylamine polymer, a vinylamine polymer, and an ethyleneimine polymer from the viewpoint of obtaining further excellent polishing selectivity of the insulating material with respect to the stopper material. preferable. These polymers can be obtained by polymerizing at least one monomer component selected from the group consisting of allylamine, diallylamine, vinylamine, ethyleneimine, and derivatives thereof. The polymer may have a structural unit derived from a monomer component other than allylamine, diallylamine, vinylamine, ethyleneimine and derivatives thereof, acrylamide, dimethylacrylamide, diethylacrylamide, hydroxyethylacrylamide, acrylic acid, It may have a structural unit derived from methyl acrylate, methacrylic acid, maleic acid, sulfur dioxide or the like.

Cationic polymers include allylamine, diallylamine, vinylamine, ethyleneimine homopolymer (polyallylamine, polydiallylamine, polyvinylamine, polyethyleneimine); homopolymers of derivatives of these monomer components; allylamine, diallylamine, Examples thereof include a copolymer having a structural unit derived from vinylamine, ethyleneimine or a derivative thereof. In the copolymer, the arrangement of structural units is arbitrary. For example, (a) a form of block copolymer in which the same type of structural units are continuous, (b) a form of random copolymerization in which the structural units A and B are particularly ordered, (c) structural units A and structural units It can take any form, including alternating copolymerization forms in which B are arranged alternately. The cationic polymer may form a salt. Examples of such salts include organic acid salts such as acetic acid; halogen acid salts such as hydrochloride and bromate; inorganic acid salts such as phosphate, sulfate, nitrate, and carbonate.

The allylamine polymer is a polymer having a structure obtained by polymerizing allylamine or a derivative thereof, and examples thereof include a polymer having a structural unit represented by the following formula (VIII) or (IX). Examples of the allylamine derivative include alkoxycarbonylated allylamine, methylcarbonylated allylamine, aminocarbonylated allylamine, ureated allylamine and the like.

[In the formula, each R independently represents a hydrogen atom or a monovalent organic group, and X ⁻ represents an anion.]

The diallylamine polymer is a polymer having a structure obtained by polymerizing diallylamine or a derivative thereof, and examples thereof include a polymer having a structural unit represented by the following formula (X) or (XI). 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 ammonium salts include ammonium chloride.

[In the formula, each R independently represents a hydrogen atom or a monovalent organic group, and X ⁻ represents an anion. ]

The vinylamine polymer is a polymer having a structure obtained by polymerizing vinylamine or a derivative thereof, and examples thereof include a polymer having a structural unit represented by the following formula (XII). 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.

[In formula, R shows a hydrogen atom or a monovalent organic group each independently. ]

The ethyleneimine polymer is a polymer having a structure obtained by polymerizing ethyleneimine or a derivative thereof, and examples thereof include a polymer having a structural unit represented by the following formula (XIII). Examples of the ethyleneimine derivative include aminoethylated acrylic polymer, alkylated ethyleneimine, ureaated ethyleneimine, propylene oxideated ethyleneimine and the like.

[Wherein, R represents a hydrogen atom or a monovalent organic group. ]

Examples of the monovalent organic group represented by R in formulas (VIII) to (XIII) include an alkyl group such as a methyl group, an ethyl group, and a propyl group; and an amino group such as a primary amino group, a secondary amino group, and a tertiary amino group An amide group and the like. X ⁻ in formula (IX) and formula (XI) is an organic acid ion such as acetate ion; halide ion such as chloride ion or bromide ion; inorganic such as phosphate ion, sulfate ion, nitrate ion or carbonate ion An acid ion etc. are mentioned.

Examples of cationic polymers include acrylic polymers such as cation-modified polyacrylamide and cation-modified polydimethylacrylamide; copolymers of dialkylenetriamines such as diethylenetriamine and other monomers (dicyandiamide / diethylenetriamine copolymer, etc.) Dicyandiamide / dialkylenetriamine copolymer, etc.); polysaccharides such as chitosan, chitosan derivatives, cation-modified cellulose, cation-modified dextran; obtained by polymerizing monomers derived from structural units constituting these compounds A copolymer or the like may be used.

Among the cationic polymers, from the viewpoint of further improving the polishing selectivity of the insulating material (for example, silicon oxide) with respect to the stopper material (for example, silicon nitride and polysilicon), and from the viewpoint of further improving the polishing rate of the insulating material, Preferred are at least one selected from the group consisting of homopolymers of allylamine, homopolymers of allylamine derivatives, polymers having structural units derived from diallyldimethylammonium salts, and dicyandiamide / diethylenetriamine copolymers. More preferred is at least one selected from the group consisting of diallyldimethylammonium chloride. Cationic polymers can be used alone or in combination of two or more for the purpose of adjusting polishing properties such as polishing selectivity and flatness.

The lower limit of the weight average molecular weight of the cationic polymer is preferably 100 or more, more preferably 300 or more from the viewpoint of further improving the polishing selectivity of the insulating material (for example, silicon oxide) with respect to the stopper material (for example, silicon nitride and polysilicon). 500 or more is more preferable. The upper limit of the weight average molecular weight of the cationic polymer is preferably 1000 × 10 ³ or less from the viewpoint of further improving the polishing selectivity of the insulating material (eg, silicon oxide) with respect to the stopper material (eg, silicon nitride and polysilicon), and 800 × 10 ³ or less is more preferable, and 500 × 10 ³ or less is more preferable. From the above viewpoint, the weight average molecular weight of the cationic polymer is more preferably 100 or more and 1000 × 10 ³ or less. The weight average molecular weight of the cationic polymer can be measured by the same method as the weight average molecular weight of the first additive.

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 abrasive, from the viewpoint of further improving polishing selectivity and flatness. 0.0005% by mass or more is more preferable, and 0.001% by mass or more is particularly preferable. The upper limit of the content of the cationic polymer is preferably 1% by mass or less, more preferably 0.5% by mass or less, more preferably 0.1% by mass, based on the total mass of the abrasive, from the viewpoint of further excellent polishing selectivity. The following is more preferable, 0.05% by mass or less is particularly preferable, 0.03% by mass or less is extremely preferable, and 0.01% by mass or less is very preferable. From the above viewpoint, the content of the cationic polymer is more preferably 0.0001% by mass or more and 1% by mass or less based on the total mass of the abrasive. 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. From the viewpoint of further improving the polishing rate of the insulating material, the polishing selectivity of the insulating material with respect to the stopper material (for example, silicon nitride and polysilicon), and the flatness, the content of the cationic polymer can be improved. It is preferable to adjust appropriately according to the type or filming conditions.

[Third additive]
The abrasive according to this embodiment includes the first additive and the second additive for the purpose of adjusting polishing characteristics such as polishing speed; abrasive characteristics such as abrasive dispersibility and storage stability. In addition, a third additive may be further contained. The amino group-containing sulfonic acid compound described later is not included in the third additive referred to here.

Examples of the third additive include carboxylic acid and amino acid. These may be used alone or in combination of two or more. By using these compounds, the balance between abrasive dispersibility and polishing characteristics is improved. In addition, although an amino acid has a carboxyl group, the compound corresponding to an amino acid is excluded as carboxylic acid.

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, caproic acid, and lactic acid.

Amino acids have the effect of improving the dispersibility of abrasive grains containing a hydroxide of a tetravalent metal element and further improving the polishing rate of the insulating material. As amino acids, arginine, lysine, aspartic acid, glutamic acid, asparagine, glutamine, histidine, proline, tyrosine, tryptophan, serine, threonine, glycine, α-alanine, β-alanine, methionine, cysteine, phenylalanine, leucine, valine, isoleucine Etc.

When using the third additive, the content of the third additive is based on the total mass of the abrasive from the viewpoint of obtaining the additive effect of the third additive while suppressing sedimentation of the abrasive grains. 0.001 mass% or more and 10 mass% or less are preferable. In addition, when using a some compound as a 3rd additive, it is preferable that the sum total of content of each compound satisfy | fills the said range.

[Amino group-containing sulfonic acid compound]
The polishing agent according to the second embodiment contains an amino group-containing sulfonic acid compound as another additive different from the first additive and the second additive. In addition, the abrasive according to the first embodiment may contain an amino group-containing sulfonic acid compound as another additive different from the first additive and the second additive. The “amino group-containing sulfonic acid compound” means at least one selected from the group consisting of a sulfonic acid group (sulfo group, —SO ₃ H) and a sulfonic acid group (—SO ₃ M: M is a metal atom), an amino group (—NH ₂ ) in one molecule. Examples of the metal atom M of the sulfonate group include alkali metals such as Na and K, and alkaline earth metals such as Mg and Ca. By using the amino group-containing sulfonic acid in combination with the first additive and the second additive, polishing of the insulating material after exposure to the stopper (for example, the insulating material embedded in the recess) is suppressed, and the dishing progresses. Therefore, high flatness can be obtained. Amino group-containing sulfonic acid compounds may be used alone or in combination of two or more for the purpose of adjusting polishing properties such as polishing selectivity and flatness.

The mechanism by which the amino group-containing sulfonic acid compound suppresses the progress of dishing is presumed as follows. The sulfonyl group (—S (═O) ₂ —) is considered to form a protective layer on the surface of the insulating material by forming a hydrogen bond with a hydroxyl group (—OH) on the surface of the insulating material (eg, silicon oxide). . Thereby, it is considered that overpolishing of the insulating material is suppressed and the progress of dishing is suppressed. At this time, the amino group also has hydrogen bonding ability, but it is considered that a highly polar sulfonyl group acts preferentially. The reason why the amino group-containing sulfonic acid compound selectively protects only the concave portion is that the adsorption force to the material to be polished is weak and the amino group-containing sulfonic acid compound is detached at the convex portion where a higher load is applied. Is considered to progress.

From this point of view, the amino group-containing sulfonic acid compound preferably has a small number of sulfonic acid groups and sulfonic acid groups and amino groups present in one molecule. The total of sulfonic acid groups and sulfonic acid groups present in one molecule is preferably 5 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1. Further, the amino group present in one molecule is preferably 5 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1.

Further, from the same viewpoint, the upper limit of the molecular weight of the amino group-containing sulfonic acid compound is preferably 1000 or less, more preferably 800 or less, and even more preferably 500 or less. The lower limit of the molecular weight of the amino group-containing sulfonic acid compound is, for example, 97 or more.

The amino group-containing sulfonic acid compound is preferably a compound having one amino group and one sulfonic acid group or one sulfonic acid group in one molecule, specifically, sulfamic acid (also known as amidosulfuric acid); Aminomethanesulfonic acid, aminoethanesulfonic acid (1-aminoethanesulfonic acid, 2-aminoethanesulfonic acid (also known as taurine), etc.), aminoalkylsulfonic acid such as aminopropanesulfonic acid; aminobenzenesulfonic acid (alternic acid (also known as alternative acid) 2-aminobenzenesulfonic acid), metanilic acid (also known as 3-aminobenzenesulfonic acid), sulfanilic acid (also known as 4-aminobenzenesulfonic acid)), aminonaphthalenesulfonic acid and the like; salts thereof; Etc.

As the amino group-containing sulfonic acid compound, aminoalkyl sulfonic acid and fragrance are used from the viewpoint of further improving the flatness by further suppressing the polishing of the insulating material after exposure to the stopper (for example, the insulating material embedded in the recess). At least one selected from the group consisting of group aminosulfonic acids is preferred, at least one selected from the group consisting of aminoethanesulfonic acid, alternic acid, metanilic acid and sulfanilic acid is more preferred, from aminoethanesulfonic acid and sulfanilic acid More preferably, at least one selected from the group consisting of

From the viewpoint of further improving the flatness, the lower limit of the content of the amino group-containing sulfonic acid compound is preferably 0.0005% by mass or more, more preferably 0.001% by mass or more, based on the total mass of the abrasive. 0.002% by mass or more is more preferable, and 0.005% by mass or more is particularly preferable. The upper limit of the content of the amino group-containing sulfonic acid compound is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, based on the total mass of the abrasive, from the viewpoint of further improving the polishing rate of the insulating material. 0.09% by mass or less is more preferable, 0.08% by mass or less is particularly preferable, 0.07% by mass or less is extremely preferable, and 0.06% by mass or less is very preferable. From the above viewpoint, the content of the amino group-containing sulfonic acid compound is more preferably 0.0005% by mass or more and 0.2% by mass or less based on the total mass of the abrasive. In addition, when using a some compound as an amino group containing sulfonic acid compound, it is preferable that the sum total of content of each compound satisfy | fills the said range. The content of the amino group-containing sulfonic acid compound is determined from the viewpoint of further improving the polishing rate of the insulating material, the polishing selectivity of the insulating material with respect to the stopper material, and the flatness (kind or filming conditions). It is preferable to adjust appropriately according to.

(Water-soluble polymer)
The polishing agent according to this embodiment has flatness, in-plane uniformity, polishing selectivity of silicon oxide with respect to silicon nitride (silicon oxide polishing rate / silicon nitride polishing rate), and polishing selectivity of silicon oxide with respect to polysilicon ( A water-soluble polymer may be contained for the purpose of adjusting polishing characteristics such as (silicon oxide 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 at 25 ° C. The first additive and the second additive are not included in the “water-soluble polymer”.

The water-soluble polymer is not particularly limited, and is a polysaccharide such as alginic acid, pectinic acid, carboxymethylcellulose, agar, curdlan, guar gum, or the like; a vinyl polymer such as polyvinyl alcohol, polyvinyl pyrrolidone, or polyacrolein; Examples thereof include glycerin polymers such as glycerin derivatives. The water-soluble polymers can be used alone or in combination of two or more.

When the water-soluble polymer is used, the lower limit of the content of the water-soluble polymer is 0 on the basis of the total mass of the abrasive from the viewpoint of obtaining the effect of adding the water-soluble polymer while suppressing sedimentation of the 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 5% by mass or less, preferably 1% by mass based on the total mass of the abrasive, from the viewpoint of obtaining the effect of adding the water-soluble polymer while suppressing sedimentation of the abrasive grains. The following is more preferable, and 0.5% by mass or less is still more preferable. From the above viewpoint, the content of the water-soluble polymer is more preferably 0.0001% by mass or more and 5% by mass or less based on the total mass of the abrasive. 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.

(Abrasive properties)
The lower limit of the pH of the abrasive according to the first embodiment is preferably 3.0 or more, more preferably 3.5 or more, still more preferably 3.8 or more, from the viewpoint of further improving the polishing rate of the insulating material. 0.0 or more is particularly preferable. The upper limit of the pH is preferably 7.0 or less, more preferably 6.5 or less, and even more preferably 6.0 or less from the viewpoint of further improving the polishing rate of the insulating material. From the above viewpoint, the pH of the abrasive is more preferably 3.0 or more and 7.0 or less. The pH is defined as the pH at a liquid temperature of 25 ° C.

The lower limit of the pH of the abrasive according to the second embodiment is preferably 3.0 or more, more preferably 3.5 or more, still more preferably 4.0 or more, from the viewpoint of further improving the polishing rate of the insulating material. .5 or more is particularly preferable. The upper limit of the pH is preferably 7.0 or less, more preferably 6.5 or less, still more preferably 6.0 or less, and particularly preferably 5.5 or less from the viewpoint of further improving the polishing rate of the insulating material. From the above viewpoint, the pH of the abrasive is more preferably 3.0 or more and 7.0 or less. The pH is defined as the pH at a liquid temperature of 25 ° C.

The pH of the polishing agent can be adjusted with an acid component such as an inorganic acid or an organic acid; an alkali component such as ammonia, sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide (TMAH), imidazole, or 2-methylimidazole. A buffer may be added to stabilize the pH. Examples of such a buffer include acetate buffer and phthalate buffer.

The pH of the abrasive 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, The value is measured after the electrode is placed in an abrasive and stabilized after 2 minutes or more. At this time, the liquid temperature of the standard buffer and the abrasive is both 25 ° C.

The abrasive according to this embodiment may be stored as a one-component abrasive containing at least abrasive grains, a first additive, a second additive, and water. ) And an additive liquid (second liquid) are mixed into a slurry and an additive liquid so that the composition of the abrasive is divided into a slurry and an additive liquid so as to become the abrasive. Set). The slurry includes at least abrasive grains and water, for example. The additive liquid includes, for example, at least a first additive, a second additive, and water. The first additive, the second additive, the third additive, the amino group-containing sulfonic acid compound, the water-soluble polymer, and the buffer solution are preferably included in the additive solution among the slurry and the additive solution. For example, in the abrasive set, the constituents of the abrasive are stored separately in a slurry (first liquid) and an additive liquid (second liquid), and the slurry contains abrasive grains and water, and the additive liquid May be an embodiment containing the first additive, the second additive, the amino group-containing sulfonic acid compound and water. The constituents of the abrasive may be stored as an abrasive set divided into three or more liquids.

In the abrasive set, slurry and additive liquid are mixed immediately before or during polishing to prepare an abrasive. In addition, the one-component abrasive is stored as an abrasive stock solution with a reduced water content, and may be diluted with water immediately before or during polishing. The two-component abrasive set is stored as a slurry storage solution and an additive storage solution with a reduced water content, and may be diluted with water immediately before or during polishing.

In the case of a one-pack type abrasive, as a method of supplying the abrasive onto the polishing surface plate, a method of feeding and supplying the abrasive directly; a storage solution for abrasive and water are sent through separate pipes, A method in which these are combined, mixed and supplied; a method in which an abrasive stock solution and water are mixed and supplied in advance can be used.

When storing as a two-component abrasive set divided into slurry and additive solution, the polishing rate can be adjusted by arbitrarily changing the combination of these two components. In the case of polishing using an abrasive set, methods for supplying the abrasive onto the polishing surface plate include the following methods. For example, the slurry and the additive liquid are sent through separate pipes, and these pipes are combined, mixed and supplied; the slurry storage liquid, the additive liquid storage liquid and water are sent through separate pipes, A method in which these are combined and mixed and supplied; a method in which slurry and additive solution are mixed and supplied in advance; and a method in which slurry storage solution, additive solution storage solution and water are mixed in advance and supplied it can. Moreover, the method of supplying the slurry and additive liquid in the said abrasive | polishing agent set on a polishing surface plate, respectively can also be used. In this case, the surface to be polished is polished using an abrasive obtained by mixing the slurry and the additive liquid on the polishing platen.

<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-part polishing agent, and the slurry and additive liquid in the polishing agent set are mixed. You may provide the grinding | polishing process of grind | polishing the to-be-polished surface of a base | substrate using the obtained abrasive | polishing agent. In addition, the substrate polishing method according to the present embodiment may be a substrate polishing method having an insulating material and a stopper material. For example, the one-part abrasive or the slurry and additive liquid in the abrasive set A polishing step of selectively polishing the insulating material with respect to the stopper material may be provided using an abrasive obtained by mixing the above. In this case, the base body may have, for example, a member containing an insulating material and a member (stopper) containing a stopper material. The stopper material is preferably at least one selected from the group consisting of polysilicon and silicon nitride. In the polishing method using the abrasive according to the first embodiment, the stopper material is more preferably polysilicon. In the polishing method using the abrasive according to the second embodiment, silicon nitride is more preferable as the stopper material.

In the polishing step, for example, the abrasive 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 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 (film to be polished), and may be a silicon oxide film, a polysilicon film, a silicon nitride film, or the like.

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

In the present embodiment, a base having an insulating material (for example, silicon oxide) 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 The insulating material in can be polished. 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, and thus the flatness of the insulating material after polishing can be improved.

Hereinafter, the polishing method according to this embodiment will be further described by taking as an example a polishing method for a semiconductor substrate on which an insulating material is formed. 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. For example, a motor or the like whose rotation speed can be changed is attached to each of the holder and the polishing surface plate. Examples of the polishing apparatus include an APPLIED MATERIALS polishing apparatus (trade name: Mira-3400, Reflexion LK) and a polishing apparatus manufactured by Ebara Corporation (trade name: F REX-300).

As the polishing pad, general nonwoven fabric, foam, non-foam, etc. can be used. Examples of the material of the polishing pad include polyurethane, acrylic, 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 can be used. As the material of the polishing pad, foamed polyurethane and non-foamed polyurethane are particularly preferable from the viewpoint of obtaining a further excellent polishing rate and flatness. The polishing pad may be grooved so that the abrasive is collected.

Although there are no restrictions on the polishing conditions, the rotation speed of the polishing platen is preferably 200 min ⁻¹ (rpm) or less so that the semiconductor substrate does not pop out, and the polishing pressure (processing load) applied to the semiconductor substrate causes polishing scratches. From the viewpoint of sufficiently suppressing this, 100 kPa or less is preferable. During polishing, it is preferable to continuously supply the polishing agent 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 the abrasive | polishing agent.

The semiconductor substrate after 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 to improve cleaning efficiency. Further, after cleaning, it is preferable to dry the semiconductor substrate after water droplets adhering to the semiconductor substrate are removed using a spin dryer or the like.

The abrasive, the abrasive set and the polishing method according to this embodiment can be suitably used for forming STI. The lower limit of the polishing selection ratio of the insulating material (eg, silicon oxide) to the stopper material (eg, silicon nitride and polysilicon) is preferably 50 or more, more preferably 120 or more, still more preferably 180 or more, and particularly preferably 200 or more. When using the abrasive | polishing agent which concerns on one Embodiment, 210 or more are very preferable. When the polishing selection ratio is less than 50, the polishing rate of the insulating material with respect to the polishing rate of the stopper material is small, and it is difficult to stop polishing at a predetermined position when forming the STI. On the other hand, when the polishing selection ratio is 50 or more, the polishing can be easily stopped, which is more suitable for the formation of STI.

The abrasive, the abrasive 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 or boron-phosphorus-silicate glass is used, and further, silicon oxyfluoride, fluorinated amorphous carbon, and the like can be used.

The abrasive, the abrasive set and the polishing method according to this embodiment can be applied to materials other than insulating materials such as silicon oxide. Examples of 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 agent, the polishing agent 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, and the like. It can also be applied to substrates.

The polishing agent, the polishing agent 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.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

(1) Synthesis of Tetravalent Metal Element Hydroxide 7.603 [L] of water was placed in a container, and then a 50% by weight aqueous cerium ammonium nitrate solution (chemical formula Ce (NH ₄ ) ₂ (NO ₃ ) ₆ , Formula amount 548.2 g / mol, manufactured by Nippon Chemical Industry Co., Ltd., product name 50% CAN solution) was added and mixed in an amount of 0.715 [L]. Thereafter, the liquid temperature was adjusted to 40 [° C.] to obtain a metal salt aqueous solution (metal salt concentration: 0.114 mol / L).

Next, after imidazole was dissolved in water to prepare an aqueous solution having a concentration of 0.7 [mol / L] for 4.566 [L], the liquid temperature was adjusted to 40 [° C.] to obtain an alkaline solution.

The container containing the metal salt aqueous solution was placed in a water tank filled with water. The water temperature of the water tank was adjusted to 40 [° C.] using an external circulation device COOLNICS circulator (manufactured by Tokyo Rika Kikai Co., Ltd. (EYELA), product name cooling thermopump CTP101). While maintaining the water temperature at 40 [° C.], while stirring the aqueous metal salt solution at a stirring speed of 400 [min ⁻¹ ], the alkali solution was mixed in the container at a mixing speed of 8.5 × 10 ⁻⁶ [m ³ / min]. In addition, a slurry precursor 1 containing abrasive grains containing tetravalent cerium hydroxide was obtained. The pH of the slurry precursor 1 was 2.2. The aqueous metal salt solution was stirred using a three-blade pitch paddle with a total length of 5 cm.

Using a hollow fiber filter with a molecular weight cut off of 50000, the obtained slurry precursor 1 was ultrafiltered while being circulated, and the ion content was removed until the conductivity was 50 mS / m or less. 2 was obtained. The ultrafiltration was performed using a liquid level sensor while adding water so that the water level of the tank containing the slurry precursor 1 was kept constant. By taking an appropriate amount of the obtained slurry precursor 2 and measuring the mass before and after drying, the nonvolatile content of the slurry precursor 2 (content of abrasive grains containing tetravalent cerium hydroxide) was calculated. In addition, when the non-volatile content was less than 1.0% by mass at this stage, it was further concentrated to an extent exceeding 1.1% by performing ultrafiltration. Finally, an appropriate amount of water was added to prepare a cerium hydroxide slurry stock solution (particle content: 1.0 mass%). The cerium hydroxide slurry stock solution was used in Experiment A and Experiment B below.

An appropriate amount of a cerium hydroxide slurry stock solution was collected and diluted with water so that the abrasive grain content was 0.2% by mass to obtain a measurement sample (aqueous dispersion). About 4 mL of the measurement sample was placed in a 1 cm square cell, and the cell was installed in a device name: N5 manufactured by Beckman Coulter. The dispersion medium was set to have a refractive index of 1.33 and a viscosity of 0.887 mPa · s, measured at 25 ° C., and the displayed average particle size value was defined as the average secondary particle size of the abrasive grains. The result was 21 nm.

(2) Experiment A
<Preparation of abrasive for CMP>
[Example A1]
100 g of an additive stock solution containing 10% by weight of maltose [manufactured by Sanwa Starch Co., Ltd., Sanmalto-S], 0.08% by weight of 2-methylimidazole, 0.06% by weight of acetic acid and 89.86% by weight of water Then, 50 g of a cerium hydroxide slurry storage solution, 820 g of water, and 30 g of an aqueous solution containing 0.1% by mass of polydiallyldimethylammonium chloride [Senka Co., Ltd., Unisense FPA1000L] as a cationic polymer are mixed. Thus, an abrasive for CMP (1000 g) having the composition shown in Table 1 was prepared. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of maltose, and 0.003% by mass of polydiallyldimethylammonium chloride. In addition, when the weight average molecular weight of the said maltose was measured on condition of the following, it was 259 (theoretical value from a chemical structure is 342).

[Example A2]
Maltose as a dextrin [Sandek # 300, manufactured by Sanwa Starch Co., Ltd. DE value (Dextrose Equivalent value): 31 to 36 (value according to “LANE-EYNON method”, the same shall apply hereinafter), moisture: 4% by mass or less. A polishing slurry for CMP having the composition shown in Table 1 was prepared in the same manner as in Example A1 except that all were changed to the manufacturer's nominal values. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of dextrin, and 0.003% by mass of polydiallyldimethylammonium chloride. When the weight average molecular weight of the dextrin was measured in the same manner as in Example A1, it was 2.1 × 10 ³ . The dextrin has at least one selected from the group consisting of a structural unit represented by the formula (IA) and a structural unit represented by the formula (IB).

[Example A3]
Maltose as a dextrin [Sandek # 180, manufactured by Sanwa Starch Co., Ltd. DE value: 22 to 25, moisture: 5% by mass or less. A polishing slurry for CMP having the composition shown in Table 1 was prepared in the same manner as in Example A1 except that all were changed to the manufacturer's nominal values. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of dextrin, and 0.003% by mass of polydiallyldimethylammonium chloride. When the weight average molecular weight of the dextrin was measured in the same manner as in Example A1, it was 5.4 × 10 ³ . The dextrin has at least one selected from the group consisting of a structural unit represented by the formula (IA) and a structural unit represented by the formula (IB).

[Example A4]
Maltose as a dextrin [Sandek # 100, manufactured by Sanwa Starch Co., Ltd. DE value: 13 to 16, water content: 5% by mass or less. A polishing slurry for CMP having the composition shown in Table 1 was prepared in the same manner as in Example A1 except that all were changed to the manufacturer's nominal values. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of dextrin, and 0.003% by mass of polydiallyldimethylammonium chloride. When the weight average molecular weight of the dextrin was measured in the same manner as in Example A1, it was 18.4 × 10 ³ . The dextrin has at least one selected from the group consisting of a structural unit represented by the formula (IA) and a structural unit represented by the formula (IB).

[Example A5]
Maltose as dextrin [manufactured by Sanei Saccharification Co., Ltd., NSD # 700 (powder type). A polishing slurry for CMP having the composition shown in Table 1 was prepared in the same manner as in Example A1, except that the DE value was changed to 17 to 21 (manufacturer nominal value). The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of dextrin, and 0.003% by mass of polydiallyldimethylammonium chloride. When the weight average molecular weight of the dextrin was measured in the same manner as in Example A1, it was 7.9 × 10 ³ . The dextrin has at least one selected from the group consisting of a structural unit represented by the formula (IA) and a structural unit represented by the formula (IB).

[Example A6]
A polishing slurry for CMP having the composition shown in Table 1 was prepared in the same manner as in Example A5 except that polydiallyldimethylammonium chloride was changed to a dicyandiamide / diethylenetriamine copolymer [Senka Co., Ltd., Unisense KHP10L]. The abrasive for CMP contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of dextrin, and 0.003% by mass of a dicyandiamide / diethylenetriamine copolymer.

[Example A7]
When preparing 100 g of the stock solution for additive solution, the amount of acetic acid added was changed to 0.1% by mass, and the amount of water increased by acetic acid was reduced. A polishing slurry for CMP having the following composition was prepared. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of dextrin, and 0.003% by mass of polydiallyldimethylammonium chloride.

[Example A8]
Maltose reduced dextrin [Matsuya Chemical Co., Ltd., H-PDX. The water content is 5% by mass or less. ] A polishing slurry for CMP having the composition shown in Table 1 was prepared in the same manner as in Example A1 except that the above was changed. The abrasive for CMP contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of reduced dextrin, and 0.003% by mass of polydiallyldimethylammonium chloride. When the weight average molecular weight of the reduced dextrin was measured by the same method as in Example A1, it was 2.0 × 10 ³ . The reduced dextrin has at least one selected from the group consisting of a structural unit represented by the formula (IA) and a structural unit represented by the formula (IB).

[Comparative Example A1]
Glucose [Wako Pure Chemical Industries, Ltd., Wako first grade D (+)-glucose. Molecular weight: 130] 100 g of additive solution containing 10% by mass, 0.08% by mass of 2-methylimidazole, 0.06% by mass of acetic acid and 89.86% by mass of water, and a storage solution for cerium hydroxide slurry By mixing 50 g and 850 g of water, an abrasive for CMP (1000 g) having the composition described in Table 2 was prepared. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide and 1.0% by mass of glucose.

[Comparative Example A2]
Glucose [Wako Pure Chemical Industries, Ltd., Wako first grade D (+)-glucose. Molecular weight: 130] 100 g of additive solution containing 10% by mass, 0.08% by mass of 2-methylimidazole, 0.06% by mass of acetic acid and 89.86% by mass of water, and a storage solution for cerium hydroxide slurry 50 g, 820 g of water, and 30 g of an aqueous solution containing 0.1% by mass of polydiallyldimethylammonium chloride [manufactured by Senka Co., Ltd., Unisense FPA1000L] as a cationic polymer, are described in Table 2. An abrasive for CMP (1000 g) was prepared. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of glucose, and 0.003% by mass of polydiallyldimethylammonium chloride.

[Comparative Example A3]
A polishing slurry for CMP having the composition described in Table 2 was prepared in the same manner as in Comparative Example A1, except that glucose was changed to dextrin (Sandex # 300, manufactured by Sanwa Starch Co., Ltd.). The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide and 1.0% by mass of dextrin.

[Comparative Example A4]
A polishing slurry for CMP having the composition shown in Table 2 was prepared in the same manner as in Comparative Example A1, except that glucose was changed to dextrin [Sandek # 180, manufactured by Sanwa Starch Co., Ltd.]. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide and 1.0% by mass of dextrin.

[Comparative Example A5]
A polishing slurry for CMP having the composition shown in Table 2 was prepared in the same manner as in Comparative Example A1 except that glucose was changed to dextrin [manufactured by Sanei Saccharification Co., Ltd., NSD # 700]. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide and 1.0% by mass of dextrin.

[Comparative Example A6]
Glucose dextrin [Sandex # 30, manufactured by Sanwa Starch Co., Ltd. DE value: 3 to 7, moisture: 5% by mass or less. A CMP polishing slurry having the composition shown in Table 2 was prepared in the same manner as in Comparative Example A2 except that all were changed to the manufacturer's nominal values. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of dextrin, and 0.003% by mass of polydiallyldimethylammonium chloride. The weight average molecular weight of the dextrin was measured by the same method as in Example A1, and found to be 147 × 10 ³ .

[Comparative Example A7]
Glucose was dextrin [NSD # 300, manufactured by Sanei Saccharification Co., Ltd. A polishing slurry for CMP having the composition shown in Table 2 was prepared in the same manner as in Comparative Example A2, except that the DE value was changed to 10 to 12 (manufacturer nominal value). The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of dextrin, and 0.003% by mass of polydiallyldimethylammonium chloride. In addition, it was 20.4 * 10 < ³ > when the weight average molecular weight of the said dextrin was measured by the method similar to Example A1.

<Liquid property evaluation>
The pH of the CMP polishing slurry obtained above and the average particle size of the abrasive grains were evaluated under the following conditions.

(PH)
Measurement temperature: 25 ± 5 ° C
Measuring device: manufactured by Electrochemical Instrument Co., Ltd., model number PHL-40
Measurement method: After calibrating two points using a standard buffer (phthalate pH buffer, pH: 4.01 (25 ° C.); neutral phosphate pH buffer, pH 6.86 (25 ° C.)), The electrode was placed in a CMP abrasive and the pH after the passage of 2 minutes or more and stabilized was measured with the measuring device. The results are shown in Tables 1 and 2.

(Average grain size of abrasive grains)
An appropriate amount of an abrasive for CMP was collected and diluted with water so that the abrasive grain content was 0.2% by mass to obtain a measurement sample (aqueous dispersion). About 4 mL of the measurement sample was placed in a 1 cm square cell, and the cell was installed in a device name: N5 manufactured by Beckman Coulter. The dispersion medium was set to have a refractive index of 1.33 and a viscosity of 0.887 mPa · s, measured at 25 ° C., and the displayed average particle size value was defined as the average particle size (average secondary particle size). As a result, the average particle diameter was in the range of 14 to 16 nm in both Examples and Comparative Examples.

<CMP evaluation>
The substrate to be polished was polished under the following polishing conditions using each of the CMP polishing agents.

(CMP conditions)
・ Polishing device: Mirra-3400 (manufactured by APPLIED MATERIALS)
・ CMP abrasive flow rate: 200 mL / min
Substrate to be polished: a blanket wafer on which a pattern is not formed, a substrate in which a silicon oxide film having a thickness of 1 μm (1000 nm) is formed on a silicon substrate by a plasma CVD method, and polysilicon having a thickness of 0.2 μm (200 nm) A substrate in which a film was formed on a silicon substrate by a CVD method and a substrate in which a silicon nitride film having a thickness of 0.2 μm (200 nm) was formed on a silicon substrate by a CVD method were used. However, the polishing of the polysilicon film was performed only for some examples and comparative examples.
Polishing pad: foamed polyurethane resin having closed cells (Rohm and Haas Japan, model number IC1010), Shore D hardness: 60
Polishing pressure: 20 kPa (3.0 psi)
・ Number of rotations of substrate and polishing surface plate: Substrate / polishing surface plate = 93/87 min ⁻¹ (rpm)
・ Polishing time: 1 min
-Cleaning and drying of wafer: After CMP treatment, cleaning with a PVA brush (polyvinyl alcohol brush) was performed, followed by drying with a spin dryer.

<Evaluation items for polished products>
[Blanket wafer polishing speed]
Polishing rate of each film to be polished (silicon oxide film, silicon nitride film and polysilicon film) polished and cleaned under the above conditions (silicon oxide film polishing rate: SiO ₂ RR, silicon nitride film polishing rate: SiNRR, polysilicon The film polishing rate: p-SiRR) was determined from the following formula. Further, polishing selection ratios SiO ₂ RR / SiNRR and SiO ₂ RR / p-SiRR were determined. In addition, the film thickness difference of each to-be-polished film | membrane before and behind grinding | polishing was calculated | required using the optical interference type | formula film thickness apparatus (Filmetrics company make, brand name: F80).
(Polishing rate: RR) = (Thickness difference of each film to be polished before and after polishing (nm)) / (Polishing time (min))

Tables 1 and 2 show the measurement results obtained in Examples A1 to A8 and Comparative Examples A1 to A7.

The symbols in the above table are as follows.
A1: San Marto-S (Maltos)
A2: Sandeck # 300 (dextrin)
A3: Sandeck # 180 (dextrin)
A4: Sandeck # 100 (dextrin)
A5: NSD # 700 (dextrin)
A6: H-PDX (reduced dextrin)
A7: D (+)-glucose A8: Sandeck # 30 (dextrin)
A9: NSD # 300 (dextrin)
P1: Polydiallyldimethylammonium chloride P2: Dicyandiamide / diethylenetriamine copolymer

Hereinafter, the results shown in Tables 1 and 2 will be described in detail.

In Example A1, SiO ₂ RR is 478 nm / min, SiNRR is 1.4 nm / min, p-SiRR is 1.0 nm / min, polishing selectivity SiO ₂ RR / SiNRR is 341, and polishing selectivity SiO ₂ RR / p -SiRR was 478, and the polishing selectivity ratio of the insulating material to the silicon nitride film and the polysilicon film was higher than those of Comparative Examples A1 to A7.

In Example A2, the SiO ₂ RR was 438 nm / min, the SiNRR was 0.5 nm / min, the polishing selection ratio SiO ₂ RR / SiNRR was 876, and the polishing selection ratio was higher than those of Comparative Examples A1 to A7.

In Example A3, SiO ₂ RR was 355 nm / min, SiNRR was 0.6 nm / min, p-SiRR was 0.8 nm / min, polishing selectivity SiO ₂ RR / SiNRR was 592, and polishing selectivity SiO ₂ RR / p -SiRR was 444, and the polishing selectivity ratio of the insulating material to the silicon nitride film and the polysilicon film was higher than those of Comparative Examples A1 to A7.

In Example A4, SiO ₂ RR was 316 nm / min, SiNRR was 1.8 nm / min, p-SiRR was 0.5 nm / min, polishing selectivity SiO ₂ RR / SiNRR was 176, polishing selectivity SiO ₂ RR / p -SiRR was 632, and the polishing selectivity ratio of the insulating material to the silicon nitride film and the polysilicon film was higher than those of Comparative Examples A1 to A7.

In Example A5, SiO ₂ RR was 356 nm / min, SiNRR was 0.6 nm / min, p-SiRR was 0.4 nm / min, polishing selectivity SiO ₂ RR / SiNRR was 593, and polishing selectivity SiO ₂ RR / p -SiRR was 890, and the polishing selectivity ratio of the insulating material to the silicon nitride film and the polysilicon film was higher than those of Comparative Examples A1 to A7.

In Example A6, SiO ₂ RR was 316 nm / min, SiNRR was 1.2 nm / min, polishing selectivity SiO ₂ RR / SiNRR was 263, and the polishing selectivity was higher than those of Comparative Examples A1 to A7.

In Example A7, SiO ₂ RR was 203 nm / min, SiNRR was 0.8 nm / min, polishing selectivity SiO ₂ RR / SiNRR was 254, and the polishing selectivity was higher than those of Comparative Examples A1 to A7.

In Example A8, SiO ₂ RR was 383 nm / min, SiNRR was 0.5 nm / min, polishing selectivity SiO ₂ RR / SiNRR was 766, and the polishing selectivity was higher than those of Comparative Examples A1 to A7.

In Comparative Example A1, the SiO ₂ RR was 11 nm / min, the SiNRR was 77 nm / min, and the polishing selection ratio SiO ₂ RR / SiNRR was 0.1.

In Comparative Example A2, SiO ₂ RR was 429 nm / min, SiNRR was 45 nm / min, p-SiRR was 2.1 nm / min, polishing selectivity SiO ₂ RR / SiNRR was 10, and polishing selectivity SiO ₂ RR / p-SiRR. Was 204.

In Comparative Example A3, SiO ₂ RR was 128 nm / min, SiNRR was 33 nm / min, and polishing selectivity SiO ₂ RR / SiNRR was 3.9.

In Comparative Example A4, the SiO ₂ RR was 159 nm / min, the SiNRR was 17 nm / min, and the polishing selectivity ratio SiO ₂ RR / SiNRR was 9.4.

In Comparative Example A5, SiO ₂ RR was 119 nm / min, SiNRR was 14 nm / min, p-SiRR was 4.0 nm / min, polishing selectivity SiO ₂ RR / SiNRR was 8.5, and polishing selectivity SiO ₂ RR / p -SiRR was 30.

In Comparative Example A6, SiO ₂ RR was 3.9 nm / min, SiNRR was 1.4 nm / min, and polishing selectivity SiO ₂ RR / SiNRR was 2.8.

In Comparative Example A7, the SiO ₂ RR was 2.1 nm / min, the SiNRR was 0.8 nm / min, and the polishing selectivity ratio SiO ₂ RR / SiNRR was 2.6.

(3) Experiment B
<Preparation of abrasive for CMP>
[Example B1]
Reduced dextrin [Matsuya Chemical Co., Ltd., H-PDX. The water content is 5% by mass or less. A storage solution for additive solution containing 10% by mass, 0.18% by mass of 2-methylimidazole, 0.06% by mass of acetic acid and 89.76% by mass of water, 50g of a storage solution for cerium hydroxide slurry, Aqueous solution containing 830 g of water and 0.15% by mass of polydiallyldimethylammonium chloride [manufactured by Senka Co., Ltd., Unisense FPA1000L] as a cationic polymer and 1.0% by mass of sulfanilic acid as an amino group-containing sulfonic acid compound By mixing 20 g, an abrasive for CMP (1000 g) having the composition shown in Table 3 was prepared. The abrasive for CMP includes 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of reduced dextrin, 0.003% by mass of polydiallyldimethylammonium chloride, and 0.02% of sulfanilic acid. Contains by mass%. It was 2.0 * 10 < ³ > when the weight average molecular weight of the said reduced dextrin was measured on condition of the following. The reduced dextrin has at least one selected from the group consisting of a structural unit represented by the formula (IA) and a structural unit represented by the formula (IB).

[Example B2]
Example B1 except that the content of sulfanilic acid was changed to 0.03% by mass, the content of 2-methylimidazole was changed to 0.02% by mass, and the content of acetic acid was changed to 0.005% by mass In the same manner as above, an abrasive for CMP having the composition shown in Table 3 was prepared. The abrasive for CMP includes 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of reduced dextrin, 0.003% by mass of polydiallyldimethylammonium chloride, and 0.03% of sulfanilic acid. Contains by mass%.

[Example B3]
Reduced dextrin is resistant to digestion [Miyagen Co., Ltd., Fiber Sol 2H. Moisture: 5% by mass or less. Manufacturer's nominal value], sulfanilic acid content changed to 0.01 mass%, 2-methylimidazole content changed to 0.012 mass%, and acetic acid content changed to 0.005 mass% A polishing slurry for CMP having the composition shown in Table 3 was prepared in the same manner as in Example B1 except that the above was changed. The CMP polishing slurry was 0.05% by weight of abrasive grains containing cerium hydroxide, 1.0% by weight of indigestible dextrin, 0.003% by weight of polydiallyldimethylammonium chloride, and 0.02% of sulfanilic acid. Contains 01% by mass. The indigestible dextrin has at least one selected from the group consisting of a structural unit represented by the formula (IA) and a structural unit represented by the formula (IB). In addition, it was 2.5 * 10 < ³ > when the weight average molecular weight of the said indigestible dextrin was measured by the method similar to Example B1.

[Example B4]
CMP of the composition described in Table 3 was carried out in the same manner as in Example B3 except that the content of sulfanilic acid was changed to 0.02% by mass and the content of 2-methylimidazole was changed to 0.018% by mass. A polishing slurry was prepared. The CMP polishing slurry was 0.05% by weight of abrasive grains containing cerium hydroxide, 1.0% by weight of indigestible dextrin, 0.003% by weight of polydiallyldimethylammonium chloride, and 0.02% of sulfanilic acid. Contains 02% by mass.

[Example B5]
Example B3 except that 0.01% by mass of sulfanilic acid was changed to 0.02% by mass of 2-aminoethanesulfonic acid (taurine) and the content of 2-methylimidazole was changed to 0.08% by mass. Similarly, an abrasive for CMP having the composition shown in Table 3 was prepared. The abrasive for CMP includes 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of indigestible dextrin, 0.003% by mass of polydiallyldimethylammonium chloride, 2-aminoethanesulfone. Contains 0.02% by weight of acid.

[Example B6]
The abrasive content was changed to 0.02 mass%, the sulfanilic acid content was changed to 0.06 mass%, the 2-methylimidazole content was changed to 0.033 mass%, and the acetic acid content was changed. A polishing slurry for CMP having the composition shown in Table 3 was prepared in the same manner as in Example B1, except that the amount was changed to 0.005% by mass. The abrasive for CMP is 0.02% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of reduced dextrin, 0.003% by mass of polydiallyldimethylammonium chloride, and 0.06% of sulfanilic acid. Contains by mass%.

[Comparative Example B1]
Glucose [Wako Pure Chemical Industries, Ltd., Wako first grade D (+)-glucose. Molecular weight: 130] 100 g of additive solution containing 10% by mass, 0.08% by mass of 2-methylimidazole, 0.06% by mass of acetic acid and 89.86% by mass of water, and a storage solution for cerium hydroxide slurry By mixing 50 g, 820 g of water, and 30 g of an aqueous solution containing 0.1% by mass of polydiallyldimethylammonium chloride [manufactured by Senka Co., Ltd., Unisense FPA1000L] as a cationic polymer, the composition described in Table 4 An abrasive for CMP (1000 g) was prepared. The abrasive for CMP contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of D (+)-glucose, and 0.003% by mass of polydiallyldimethylammonium chloride.

[Example B7]
For CMP having the composition shown in Table 4 in the same manner as in Example B1, except that sulfanilic acid was changed to 2-acrylamido-2-methylpropanesulfonic acid and the acetic acid content was changed to 0.005% by mass. An abrasive was prepared. The CMP abrasive is 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of reduced dextrin, 0.003% by mass of polydiallyldimethylammonium chloride, 2-acrylamido-2- It contains 0.02% by mass of methylpropanesulfonic acid.

[Example B8]
Example B1 except that the content of 2-methylimidazole was changed to 0.08% by mass, the content of acetic acid was changed to 0.005% by mass, and an abrasive for CMP was prepared without using sulfanilic acid. Similarly, an abrasive for CMP having the composition shown in Table 4 was prepared. The abrasive for CMP contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of reduced dextrin, and 0.003% by mass of polydiallyldimethylammonium chloride.

[Comparative Example B2]
A polishing slurry for CMP having the composition shown in Table 4 was prepared in the same manner as in Example B8 except that the reduced dextrin was changed to polyoxyethylene styrenated phenyl ether [Daiichi Kogyo Seiyaku Co., Ltd., Neugen EA207D]. did. The abrasive for CMP contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of polyoxyethylene styrenated phenyl ether, and 0.003% by mass of polydiallyldimethylammonium chloride.

[Comparative Example B3]
Without using a cationic polymer, the sulfanilic acid content was changed to 0.01% by mass, the acetic acid content was changed to 0.005% by mass, and the 2-methylimidazole content was 0.013% by mass. A polishing slurry for CMP having the composition shown in Table 4 was prepared in the same manner as in Example B1, except that the percentage was changed to%. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of reduced dextrin, and 0.01% by mass of sulfanilic acid.

[Comparative Example B4]
A polishing slurry for CMP having the composition shown in Table 5 was prepared in the same manner as in Example B1, except that the content of acetic acid was changed to 0.005% by mass without using reduced dextrin and cationic polymer. did. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide and 0.02% by mass of sulfanilic acid.

[Comparative Example B5]
A CMP abrasive having the composition shown in Table 5 was prepared in the same manner as in Example B8 except that the abrasive for CMP was prepared without using reduced dextrin. The CMP abrasive contains 0.05% by mass of abrasive grains containing cerium hydroxide and 0.003% by mass of polydiallyldimethylammonium chloride.

[Comparative Example B6]
A polishing slurry for CMP having the composition shown in Table 5 in the same manner as in Comparative Example B2, except that the content of 2-methylimidazole was changed to 0.017% by mass and 0.02% by mass of sulfanilic acid was added. Was prepared. The abrasive for CMP includes 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of polyoxyethylene styrenated phenyl ether, 0.003% by mass of polydiallyldimethylammonium chloride, sulfanilic acid Is contained in an amount of 0.02% by mass.

[Example B9]
CMP of the composition described in Table 5 was performed in the same manner as in Example B8 except that 0.02% by mass of p-toluenesulfonic acid was added and the content of 2-methylimidazole was changed to 0.017% by mass. A polishing slurry was prepared. The CMP polishing slurry comprises 0.05% by weight abrasive grains containing cerium hydroxide, 1.0% by weight reduced dextrin, 0.003% by weight polydiallyldimethylammonium chloride, and p-toluenesulfonic acid. Contains 0.02% by mass.

[Example B10]
The same procedure as in Example B9 except that p-toluenesulfonic acid was changed to glycine (the content was not changed and was 0.02% by mass), and the content of 2-methylimidazole was changed to 0.008% by mass. Thus, an abrasive for CMP having the composition shown in Table 5 was prepared. The CMP abrasive is 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of reduced dextrin, 0.003% by mass of polydiallyldimethylammonium chloride, and 0.02% by mass of glycine. %contains.

[Example B11]
Table 5 shows the same as in Example B2, except that the reduced dextrin was changed to maltose [Sanmalto-S, manufactured by Sanwa Starch Co., Ltd.] (content is 1.0% by mass without change). An abrasive for CMP having the composition described above was prepared. The abrasive for CMP includes 0.05% by mass of abrasive grains containing cerium hydroxide, 1.0% by mass of maltose, 0.003% by mass of polydiallyldimethylammonium chloride, and 0.03% by mass of sulfanilic acid. contains. In addition, although the theoretical value of the molecular weight of maltose is 342.30, it was 259 when the weight average molecular weight of the said maltose was measured by the method similar to Example B1.

(PH)
Measurement temperature: 25 ± 5 ° C
Measuring device: manufactured by Electrochemical Instrument Co., Ltd., model number PHL-40
Measurement method: After calibrating two points using a standard buffer (phthalate pH buffer, pH: 4.01 (25 ° C.); neutral phosphate pH buffer, pH 6.86 (25 ° C.)), The electrode was placed in a CMP abrasive and the pH after the passage of 2 minutes or more and stabilized was measured with the measuring device. The results are shown in Tables 3-5.

(Average grain size of abrasive grains)
An appropriate amount of an abrasive for CMP was collected and diluted with water so that the abrasive grain content was 0.2% by mass to obtain a measurement sample (aqueous dispersion). About 4 mL of the measurement sample was placed in a 1 cm square cell, and the cell was installed in a device name: N5 manufactured by Beckman Coulter. The dispersion medium was set to have a refractive index of 1.33 and a viscosity of 0.887 mPa · s, measured at 25 ° C., and the displayed average particle size value was defined as the average particle size (average secondary particle size). As a result, in both the examples and the comparative examples, the average particle size was in the range of 10 to 30 nm.

<CMP evaluation>
[Blanket wafer evaluation]
The substrate to be polished was polished under the following polishing conditions using each of the CMP polishing agents.

(CMP conditions)
Polishing apparatus: In Example B6, Reflexion LK (manufactured by APPLIED MATERIALS) was used, and in other examples and comparative examples, FREX-300 (manufactured by Ebara Corporation) was used.
・ CMP abrasive flow rate: 200 mL / min
Substrate to be polished: a blanket wafer on which a pattern is not formed, a substrate in which a silicon oxide film having a thickness of 1 μm (1000 nm) is formed on a silicon substrate by a plasma CVD method, and a silicon nitride having a thickness of 0.2 μm (200 nm) A substrate in which a film was formed on a silicon substrate by a CVD method was used.
Polishing pad: foamed polyurethane resin having closed cells (Rohm and Haas Japan, model number IC1010), Shore D hardness: 60
Polishing pressure: 20 kPa (3.0 psi)
・ Number of rotations of substrate and polishing surface plate: Substrate / polishing surface plate = 93/87 min ⁻¹ (rpm)
・ Polishing time: 1 min
-Cleaning and drying of wafer: After CMP treatment, cleaning with a PVA brush was performed, followed by drying with a spin dryer.

(Blanket wafer polishing speed)
The polishing rate (silicon oxide film polishing rate: SiO ₂ RR, silicon nitride film polishing rate: SiNRR) of each film to be polished (silicon oxide film, silicon nitride film) polished and cleaned under the above conditions was obtained from the following formula. . Further, the polishing selection ratio SiO ₂ RR / SiNRR was determined. In addition, the film thickness difference of each to-be-polished film | membrane before and behind grinding | polishing was calculated | required using the optical interference type | formula film thickness apparatus (Filmetrics company make, brand name: F80).
(Polishing rate: RR) = (Thickness difference of each film to be polished before and after polishing (nm)) / (Polishing time (min))

[Pattern wafer evaluation 1]
The substrate to be polished was polished under the following polishing conditions using a CMP abrasive. However, in Comparative Examples B2 to B6, the pattern wafer was not polished because the polishing selection ratio SiO ₂ RR / SiNRR on the blanket wafer was low.

(CMP conditions)
Polishing apparatus: The same polishing apparatus as that used for polishing the blanket wafer 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, a trench is formed in an exposure process, and a silicon oxide film is formed as an insulating film on the silicon substrate and the silicon nitride film so as to fill the silicon nitride film and the trench. It was a wafer obtained by laminating (SiO ₂ film). The silicon oxide film was formed by the HDP (High Density Plasma) method.
Polishing pad: foamed polyurethane resin having closed cells (Rohm and Haas Japan, model number IC1010), Shore D hardness: 60
Polishing pressure: 14 kPa (2.0 psi)
・ Number of rotations of substrate and polishing platen: substrate / polishing platen = 100/107 min ⁻¹ (rpm)
Polishing time: Polishing was performed until the silicon nitride film as a stopper was exposed. Further, the progress of dishing was confirmed by performing further polishing (performing 100% overpolishing) for the same time as the polishing time required until the silicon nitride film was exposed.
-Cleaning and drying of wafer: After CMP treatment, cleaning with a PVA brush was performed, followed by drying with a spin dryer.

The pattern wafer has a line (convex portion) & space (concave portion) width of 1000 μm pitch, 200 μm pitch, 100 μm pitch, and a convex pattern density of 50%. The line and space is a simulated pattern in which an active portion masked with a silicon nitride film that is a convex portion and a trench portion in which a groove that is a concave portion is formed are alternately arranged. 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 pattern wafer, the thickness of the silicon oxide film was 600 nm on both the silicon substrate and the silicon nitride film. Specifically, the thickness of the silicon nitride film on the silicon substrate is 150 nm, the thickness of the convex portion of the silicon oxide film is 600 nm, the thickness of the concave portion of the silicon oxide film is 600 nm, and the silicon oxide film The recess depth was 500 nm (trench depth 350 nm + silicon nitride film thickness 150 nm).

When polishing a pattern wafer, the remaining step is 100 nm or less by polishing the wafer using a known CMP abrasive having self-stopping properties (the polishing rate decreases when the remaining step of the simulated pattern decreases). The wafer in a state was used. Specifically, using an abrasive in which HS-8005-D4 manufactured by Hitachi Chemical Co., Ltd., HS-7303GP manufactured by Hitachi Chemical Co., Ltd., and water are mixed at a ratio of 2: 1.2: 6.8, A wafer in which the film thickness of the convex silicon oxide film in a 1000 μm pitch 50% density pattern was polished to 130 nm was used.

By measuring the remaining film thickness of the silicon nitride film or silicon oxide film on the convex part of the patterned wafer polished and cleaned under the above conditions and the residual film thickness of the silicon oxide film in the concave part, the amount of residual step (dishing) is obtained from the following equation: Asked. The film thickness of the film to be polished before and after polishing was determined using an optical interference film thickness apparatus (manufactured by Nanometrics, trade name: Nanospec AFT-5100).
Remaining step (dishing) = (350 nm + silicon nitride film thickness (nm)) − (recessed silicon oxide film remaining film thickness (nm))

Tables 3 to 5 show the measurement results obtained in Examples B1 to B11 and Comparative Examples B1 to B6.

The symbols in the above table are as follows.
B1: H-PDX (reduced dextrin)
B2: Fibersol 2H (digestible dextrin)
B3: D (+)-glucose B4: Neugen EA207D (polyoxyethylene styrenated phenyl ether)
B5: San Marto-S (Maltos)
P1: polydiallyldimethylammonium chloride S1: 2-acrylamido-2-methylpropanesulfonic acid

Hereinafter, the results shown in Tables 3 to 5 will be described in detail.

In Example B1, the SiO ₂ RR is 478 nm / min, the SiNRR is 0.9 nm / min, the polishing selectivity ratio SiO ₂ RR / SiNRR is 531, SiNRR is smaller than the comparative example, and the polishing selectivity ratio is the comparative example. It showed a higher value. In the pattern wafer evaluation, the remaining steps when the silicon nitride film was exposed (polishing time 13 seconds) were 11 nm, 4 nm, and 1 nm (1000 μm pitch, 200 μm pitch, and 100 μm pitch), respectively. Further, even if the polishing was further continued for 13 seconds (100% overpolishing), the remaining steps were 16 nm, 9 nm, and 2 nm, respectively. As a result, it was confirmed that the result was that the remaining step was small and the progress of dishing was suppressed both before and after over-polishing while showing a high polishing selectivity. Also, it was confirmed that good results were obtained in Examples B2 to B6 as well.

In Comparative Example B1, since the α-glucose polymer was not used, it was confirmed that the polishing selectivity was low. Moreover, in comparative example B1, since the amino group containing sulfonic acid compound was not used, it was confirmed that the progress of dishing is not suppressed.
In Examples B7 to B10, since the amino group-containing sulfonic acid compound was not used, the progress of dishing was not suppressed, but it was confirmed that the polishing selectivity was higher than that of the comparative example.
In Comparative Examples B2 and B5, it was confirmed that the polishing selectivity was low because no α-glucose polymer was used.
In Comparative Example B3, since no cationic polymer was used, it was confirmed that the polishing selection ratio was low.
In Comparative Example B4, it was confirmed that the polishing selectivity was low because α-glucose polymer and cationic polymer were not used.
In Comparative Example B6, it was confirmed that the polishing selectivity was low because no α-glucose polymer was used.
In Example B11, since α-glucose polymer having a degree of polymerization of α-glucose of 3 or more was not used, it was confirmed that although the progress of dishing was not suppressed, the polishing selectivity was higher than that of the comparative example. It was done.

[Pattern wafer evaluation 2]
A pattern wafer similar to the pattern wafer evaluation 1 was prepared except that a polysilicon film was formed instead of the silicon nitride film. When polishing was performed using the polishing agent described in Examples B1 to B6 under the same conditions as in the pattern wafer evaluation 1, the remaining step was small before and after overpolishing, and the progress of dishing was suppressed. It was confirmed that it was obtained. From this, it was confirmed that even when the stopper material is polysilicon, the polishing selectivity of the insulating material with respect to the stopper material can be improved and the progress of dishing can be suppressed.

According to the present invention, it is possible to provide a polishing agent, a polishing agent set, and a polishing method capable of improving the polishing selectivity of the insulating material with respect to the stopper material in polishing of the insulating material using the stopper. In addition, according to the present invention, in CMP technology for flattening an STI insulating material, a pre-metal insulating material, an interlayer insulating material, etc., when the insulating material is polished using a stopper, the polishing selectivity of the insulating material with respect to the stopper material is improved. A polishing agent, a polishing agent set and a polishing method that can be provided.

According to one embodiment of the present invention, it is possible to provide a polishing agent, a polishing agent set, and a polishing method capable of improving the polishing selectivity of the insulating material with respect to the stopper material and suppressing the progress of dishing in polishing of the insulating material using the stopper. . Further, according to one embodiment of the present invention, when polishing an insulating material using a stopper in CMP technology for planarizing an STI insulating material, a premetal insulating material, an interlayer insulating material, and the like, polishing selection of the insulating material with respect to the stopper material It is possible to provide a polishing agent, a polishing agent set and a polishing method capable of improving the performance and suppressing the progress of dishing.

As a stopper material, a process using polysilicon in addition to silicon nitride is also increasing. However, according to one embodiment of the present invention, even if either silicon nitride or polysilicon is used as a stopper material, insulation against the stopper material is achieved. The polishing selectivity of the material can be improved and the progress of dishing can be suppressed.

Claims

Containing water, abrasive grains containing a hydroxide of a tetravalent metal element, an α-glucose polymer, and a cationic polymer,
A polishing agent, wherein the α-glucose polymer has a weight average molecular weight of 20.0 × 10 3 or less.
Further containing an amino group-containing sulfonic acid compound,
The abrasive according to claim 1, wherein the degree of polymerization of α-glucose in the α-glucose polymer is 3 or more.
The α-glucose polymer has at least one selected from the group consisting of a structural unit represented by the following formula (IA) and a structural unit represented by the following formula (IB). The abrasive | polishing agent of 1 or 2.
The abrasive according to any one of claims 1 to 3, wherein the hydroxide of the tetravalent metal element contains a hydroxide of cerium.
The abrasive according to any one of claims 1 to 4, having a pH of 3.0 or more and 7.0 or less.
The abrasive according to any one of claims 1 to 5, which is used for polishing a surface to be polished containing silicon oxide.
The constituents of the abrasive according to any one of claims 1 to 6 are stored separately in a first liquid and a second liquid, and the first liquid contains the abrasive grains and water, An abrasive set, wherein a second liquid comprises the α-glucose polymer, the cationic polymer, and water.
The abrasive set according to claim 7, wherein the second liquid contains an amino group-containing sulfonic acid compound.
A substrate polishing method comprising a step of polishing a surface to be polished of the substrate using the abrasive according to any one of claims 1 to 6.
Polishing a substrate, comprising a step of polishing a surface to be polished of the substrate using an abrasive obtained by mixing the first liquid and the second liquid in the abrasive set according to claim 7 or 8. Method.