JP7019379B2 - Composite abrasive grains - Google Patents

Description

The present invention relates to composite abrasive grains, a polishing liquid composition using the composite abrasive grains, and a method for manufacturing a semiconductor substrate, a polishing method, and a method for manufacturing a semiconductor device using the polishing liquid composition.

Chemical mechanical polishing (CMP) technology is a method in which the surface of the substrate to be polished and the polishing pad are in contact with each other, and the polishing liquid is supplied to these contact points while the substrate to be polished and the polishing pad are relatively. By moving the surface uneven portion of the substrate to be polished is chemically reacted and mechanically removed to flatten it.

The performance of CMP technology is determined by the process conditions of CMP, the type of polishing liquid, the type of polishing pad, and the like. Among these, the polishing liquid is a factor that has the greatest influence on the performance of the CMP process. Silica (SiO ₂ ) and ceria (CeO ₂ ) are widely used as the polishing particles contained in this polishing liquid.

For example, Patent Document 1 proposes a composite oxide containing CeO ₂ and SiO ₂ having specific reducing properties as a composite oxide that can be used as an abrasive.

Currently, in the manufacturing process of semiconductor devices such as semiconductor devices, when flattening the interlayer insulating film, forming a shallow trench element separation structure (hereinafter also referred to as "element separation structure"), forming plugs and embedded metal wiring, etc. This CMP technology has become an indispensable technology. In recent years, the number of layers and high definition of semiconductor devices has dramatically increased, and there is a demand for further improvement in the yield and throughput (yield) of semiconductor devices. Along with this, in the CMP process as well, polishing scratch-free and higher speed polishing has been desired.

In particular, in the field of memory used for general purposes, improvement of throughput is an important issue, and improvement of abrasives is also progressing toward improvement of throughput. For example, when ceria is used as the polishing particles, it is generally known to increase the particle size of the polishing particles in order to improve the polishing speed of the film to be polished (silicon oxide film). If the size is increased, the quality becomes inferior due to the increase in polishing scratches, resulting in a decrease in yield.

Patent Document 2 discloses abrasive particles having polishing performance suitable for precision polishing, high polishing speed, and high monodispersity, and the abrasive particles have an average aspect ratio of 1.00 to 1.00 or more. Abrasive particles containing a predetermined amount of cerium, which are spherical particles in the range of 1.15 and have a particle diameter D ₅₀ in the range of 50 to 1500 nm.

Patent Document 3 discloses a polishing liquid containing cerium oxide particles having an average aspect ratio of 1.5 to 6.0 for the purpose of improving flatness after polishing, and Patent Document 4 discloses a short polishing solution. A polishing liquid composition containing composite oxide particles containing cerium and zirconium is disclosed for the purpose of obtaining a polished surface having high surface flatness by polishing for a long time.

Patent Document 5 describes a conditioner for a CMP polishing pad of a metal film in which superabrasive grains are fixed to the surface of a base metal by a single layer with a binder, and the superabrasive grains have a crystal face of {100}. A conditioner is disclosed in which 40% by weight or more of superabrasive grains forming a disdyakis dodecahedron composed of both {111} planes and {111} planes are contained.

International Publication No. 2012/165362 International Publication No. 2015/0198888 Japanese Unexamined Patent Publication No. 2015-224276 Japanese Unexamined Patent Publication No. 2008-277735 Japanese Unexamined Patent Publication No. 2009-136926

In the semiconductor field in recent years, high integration has progressed, and there is a demand for further complexity and miniaturization of wiring. Therefore, there is an increasing demand for faster polishing of objects to be polished such as silicon oxide films.

An object of the present invention is to provide a composite abrasive grain capable of improving the polishing speed, a polishing liquid composition using the composite abrasive grain, a method for manufacturing a semiconductor substrate, a polishing method, and a method for manufacturing a semiconductor device.

The present invention is a composite abrasive grain in which a part of the cerium atom in the cerium oxide particles is replaced with a tetravalent metal atom other than the cerium atom, and the content of the metal atom in the composite abrasive grain is the cerium. The present invention relates to composite abrasive grains having an aspect ratio of 2.0 or more and 100 or less and 8 mol% or more and 37 mol% or less with respect to the total amount of atoms and the metal atoms.

The present invention relates to a polishing liquid composition containing the composite abrasive grains of the present invention and an aqueous medium.

The present invention relates to a method for manufacturing a semiconductor substrate, which comprises a step of polishing the substrate to be polished using the polishing liquid composition of the present invention.

The present invention relates to a method for polishing a substrate, which comprises a step of polishing the substrate to be polished using the polishing liquid composition of the present invention.

The present invention relates to a method for manufacturing a semiconductor device, which comprises a step of polishing a substrate to be polished using the polishing liquid composition of the present invention.

The present invention comprises a step of mixing an aqueous solution containing cerium, an aqueous solution containing a tetravalent metal atom other than a cerium atom, and an aqueous solution containing an alkaline agent to form a precipitate, and the above-mentioned precipitate having a temperature of 100 ° C. or higher and 300 ° C. or higher. The content of the metal atom in the composite abrasive grains is 8 mol with respect to the total amount of the cerium atom and the metal atom, including the step of performing hydrothermal treatment at ° C. or lower for 6 hours or more and 120 hours or less. The present invention relates to a method for producing a composite abrasive grain, which is% or more and 37 mol% or less and has an aspect ratio of 2.0 or more and 100 or less.

According to the present invention, it is possible to provide a composite abrasive grain that can improve the polishing speed. Therefore, in the method of manufacturing a semiconductor substrate, the method of polishing a substrate, and the method of manufacturing a semiconductor device using the polishing liquid composition containing the composite abrasive grains of the present invention, it is possible to achieve the effect of increasing productivity.

The present invention is a composite abrasive grain in which a part of the cerium atom in the cerium oxide particles is replaced with a tetravalent metal atom other than the cerium atom (hereinafter, may be abbreviated as "metal atom A"). It is based on the finding that the polishing speed is remarkably improved when the aspect ratio of the composite abrasive grains is within a predetermined range.

In the present invention, the details of the mechanism for improving the polishing rate are not clear, but it is inferred as follows.

For example, the cerium oxide particles can be obtained by a build-up process as described in JP-A-2010-505735, and the obtained cerium oxide particles have a crystal structure according to the production conditions. The composite abrasive grain of the present invention is a composite oxide particle in which a cerium atom in the crystal structure is replaced with a tetravalent metal atom A having an ion radius different from that of the cerium atom, and the metal atom in the composite oxide particle is described. The content of A is 8 mol% or more and 37 mol% or less with respect to the total amount (100 mol%) of the cerium atom and the metal atom, and the aspect ratio is 2.0 or more and 100 or less. Compared with cerium oxide particles, the crystal structure is distorted and oxygen defects (pores) are increased. Therefore, due to the temperature rise that occurs during polishing, friction due to external force, etc., the valence decreases due to oxygen defects in the crystal structure, and the metal element with the reduced valence causes the surface to be polished such as a silicon oxide film. It is presumed that the movement of electrons to the surface contributes to the weakening of the surface to be polished and to the improvement of the polishing speed. However, the present invention is not construed as being limited to these mechanisms.

In the present invention, the "aspect ratio" is the ratio (long side / short side) of the "long side" and the "short side" of the composite abrasive grain, and the "long side" is an electric field emission type scanning electron microscope ( FE-SEM) The average of the maximum lengths of the composite abrasive grains (primary particles) in the observation image, and the "short side" is the average of the maximum lengths in the direction orthogonal to the "long side". Specifically, the "aspect ratio" can be obtained by the method described in Examples described later. The shape of the composite abrasive grains of the present invention is preferably rod-shaped from the viewpoint of improving the polishing speed.

The aspect ratio of the composite abrasive grains of the present invention is 2.0 or more, preferably 2.5 or more, more preferably 3 or more, further preferably 6 or more, and even more preferably 7 or more, from the viewpoint of improving the polishing speed. And, from the same viewpoint, it is 100 or less, preferably 20 or less, and more preferably 13 or less. The aspect ratio can be measured by the method described in Examples.

The short side of the composite abrasive grain of the present invention is preferably 10 nm or more, more preferably 15 nm or more, further preferably 20 nm or more, further preferably 22 nm or more, and 50 nm from the same viewpoint from the viewpoint of improving the polishing speed. Less than is preferable, 45 nm or less is more preferable, 40 nm or less is further preferable, 38 nm or less is further preferable, and 28 nm or less is further preferable. The short side of the composite abrasive grains of the present invention can be measured by the method described in Examples.

The long side of the composite abrasive grain of the present invention is preferably 60 nm or more, more preferably 100 nm or more, further preferably 200 nm or more, and from the same viewpoint, 1000 nm or less, preferably 500 nm or less, from the viewpoint of improving the polishing speed. More preferably, it is more preferably 300 nm or less. The long side of the composite abrasive grains of the present invention can be measured by the method described in Examples.

The composite abrasive grain of the present invention is a composite oxide particle in which a part of the cerium atom in the cerium oxide particle is replaced by the metal atom A. As the metal atom A, at least one selected from manganese, titanium and zirconium is preferable from the viewpoint of improving the polishing speed, but at least one selected from titanium and zirconium is more preferable from the viewpoint of ionic radius, and zirconium is more preferable. More preferred.

The content (mol%) of the metal atom A in the composite abrasive grains of the present invention is 8 mol% or more with respect to the total amount (100 mol%) of Ce and the metal atom A from the viewpoint of improving the polishing speed. Yes, 10 mol% or more is preferable, 13 mol% or more is more preferable, 18 mol% or more is preferable, and from the same viewpoint, 37 mol% or less, 30 mol% or less is preferable, and 27 mol% or less is preferable. More preferably, 22 mol% or less is further preferable.

In one embodiment, the composite abrasive grains of the present invention are substantially free of silicon (Si). Here, "substantially free" means that the Si content in the composite abrasive grains is 1% by mass or less in terms of SiO ₂ .

It is generally known that when cerium oxide particles are synthesized by a build-up method, crystal planes such as {111} plane, {100} plane, and {110} plane are exposed on the surface. From the viewpoint of improving the polishing speed, it is preferable that the surface of the composite abrasive grains in contact with the object to be polished contains a {100} surface. In the composite oxide particles in which some of the cerium atoms in the cerium oxide particles are replaced by the metal atom A, the exposure amount of the {100} surface on the surface of the composite oxide particles is 3% or more from the viewpoint of improving the polishing rate. Is preferable, 3.5% or more is more preferable, 4% or more is further preferable, and from the same viewpoint, 90% or less is preferable, 50% or less is more preferable, 30% or less is further preferable, and 20% or less is further more preferable. It is preferable, and even more preferably 14% or less. In the present invention, the {100} plane corresponds to the {200} plane corresponding to the peak appearing near 33 ° detected by the X-ray diffraction measurement of cerium oxide.

In the present invention, the exposure amount of the {100} surface can be calculated by, for example, image analysis by FE-SEM observation or the like, and specifically, one or a plurality of randomly selected particles can be calculated by FE-SEM or the like. It can be calculated from the average value of the ratio of the area of the square portion to the surface area of one particle in the observed image or the ratio of the area of the square portion to the surface area of each of the plurality of particles, and more specifically. , Can be measured by the method described in Examples. In the present invention, the square portion of the particles in the image obtained by FE-SEM observation or the like can be regarded as a {100} plane.

Examples of the method for controlling the exposure amount of the {100} surface are described in J.Phys.Chem.B 2005, 109, p24380-24385 and Crystal Growth & Design, Vol.9, No.12, p5297-5303, 2009. Method can be adopted. For example, a method for producing cerium oxide having a specific crystal shape by hydrothermal treatment under high concentration and strong alkaline conditions, or a hydroxide previously produced from a cerium raw material and an alkali under supercritical conditions (for example, 400 ° C., 38 MPa). A method of producing cerium oxide by crystallizing at the above method can be mentioned. At least one selected from monocarboxylic acids such as decanoic acid and dodecanoic acid, dicarboxylic acids such as adipic acid and pimelic acid, carboxylic acid-based polymers such as polyacrylic acid, and phosphoric acid compounds such as trisodium phosphate in the crystal growth process. By appropriately adding the seed compounds, these compounds are adsorbed on the specific crystal surface. Therefore, in the shape of the finally obtained crystal, the surface on which these compounds are adsorbed is selectively protected and remains, and the crystal shape is formed. It is thought that it will be possible to control.

The composite abrasive grain having an exposure amount of the {100} surface on the particle surface of 3% or more and 90% or less has a predetermined reduction characteristic in one embodiment, and the reduction characteristic makes it possible to improve the polishing rate. The reduction characteristics can be evaluated by the amount of water produced at 300 ° C. or lower measured by the temperature-reducing method (Temperature-Programmed-Reaction; hereinafter, also referred to as “TPR”). 8 mmol / m ² or more is preferable per unit surface area of the composite abrasive grains.

From the viewpoint of improving the polishing speed, the composite abrasive grain of the present invention preferably has a water production amount of 300 ° C. or lower measured by TPR of 8 mmol / m ² or more per unit surface area of the cerium oxide particles, preferably 10 mmol / m ² or more. Is more preferable, 12 mmol / m ² or more is further preferable, and from the same viewpoint, 200 mmol / m ² or less is preferable, 100 mmol / m ² or less is more preferable, 80 mmol / m ² or less is further preferable, and 65 mmol / m ² is more preferable. The following is even more preferable, 50 mmol / m ² or less is even more preferable, 30 mmol / m ² or less is even more preferable, 20 mmol / m ² or less is even more preferable, and 15 mmol / m ² or less is even more preferable. In the present invention, the amount of water produced by the ceria abrasive grains can be measured by the method described in Examples.

The amount of water produced can be controlled, for example, by the method described in J.Phys.Chem.B 2005, 109, p24380-24385. For example, by changing the time and reaction temperature of the hydrothermal treatment and the amount of the alkaline agent added in the crystal growth process of the method for producing cerium oxide having a specific crystal shape by hydrothermal treatment under high concentration and strong alkaline conditions. The reduction characteristics can be changed and the amount of water produced can be controlled.

The BET specific surface area calculated by the nitrogen adsorption (BET) method of the composite abrasive grains of the present invention is preferably 10 m ² / g or more, more preferably 20 m ² / g or more, and more preferably 30 m ² / g from the viewpoint of improving the polishing speed. The above is more preferable, and from the same viewpoint, 80 m ² / g or less is preferable, 70 m ² / g or less is more preferable, and 60 m ² / g or less is further preferable. In the present invention, the BET specific surface area can be measured by the method described in Examples.

[Manufacturing method of composite abrasive grains]
Next, an example of the method for producing the composite abrasive grains of the present invention will be described.
In an example of the method for producing composite abrasive grains of the present invention, first, a cerium compound having an oxidation number of 4 (hereinafter, also referred to as a cerium (IV) compound) and a zirconium compound having an oxidation number of 4 (hereinafter, zirconium (IV) compound). ) A solution containing (also referred to as a compound) and a precipitant are mixed to produce a slurry containing a precipitate. Next, the slurry containing the precipitate is hydroheat-treated at a predetermined temperature for a predetermined time in an autoclave, cooled to room temperature, and the precipitate is repeatedly washed and dried to obtain the composite abrasive grains of the present invention.

The solution containing the cerium (IV) compound and the zirconium (IV) compound is, for example, a water-soluble cerium (IV) compound such as cerium nitrate and a water-soluble zirconium (IV) compound such as zirconium nitrate in water or the like. After dissolving in the solvent of, it may be mixed and prepared.

If a precipitating agent (base solution) is added to the solution containing the cerium (IV) compound and the zirconium (IV) compound, the cerium (IV) compound and the zirconium (IV) compound are hydrolyzed to form a precipitate. Generated. It is preferable to add the precipitating agent while stirring the solution containing the cerium (IV) compound and the zirconium (IV) compound.

Examples of the precipitant include an aqueous solution containing an alkaline agent, and more specifically, an aqueous ammonia solution; an alkaline hydroxide solution such as a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution; carbonic acid of sodium, potassium, or ammonia. Salt solution; examples include a bicarbonate solution. The precipitating agent is preferably an aqueous sodium hydroxide solution, and the precipitating agent is specified because a solution containing a cerium (IV) compound and a zirconium (IV) compound can be easily set to strong alkaline conditions. , It is preferably about 2 to 10 N, and more preferably about 4 to 8 N.

The mixing time of the solution containing the cerium (IV) compound and the zirconium (IV) compound and the precipitant is preferably 10 minutes or more, and more preferably 20 minutes or more. The reaction of the solution containing the cerium (IV) compound and the zirconium (IV) compound with the precipitant can be carried out at any suitable temperature such as room temperature.

Hydrothermal treatment can be performed, for example, in an autoclave. The hydrothermal treatment temperature is preferably 100 ° C. or higher, more preferably 170 ° C. or higher, and preferably 300 ° C. or lower, from the viewpoint of obtaining composite oxide particles in which cerium oxide and zirconium oxide are highly dissolved. It is preferably 190 ° C. or lower. From the same viewpoint, the hydrothermal treatment time is preferably 6 hours or more, more preferably 23 hours or more, and preferably 120 hours or less, more preferably 25 hours or less.

Therefore, an example of the method for producing composite abrasive grains of the present invention is a step of mixing a solution in which a cerium compound and a compound containing a metal atom A are dissolved in water and an aqueous solution containing an alkaline agent to form a precipitate. The deposit is subjected to a hydrothermal treatment at 100 ° C. or higher and 300 ° C. or lower for 6 hours or more and 120 hours or less, and the content of the metal atom in the composite abrasive grains is the cerium atom and the metal. It is a method for producing composite abrasive grains, which is 8 mol% or more and 37 mol% or less and has an aspect ratio of 2.0 or more and 100 or less with respect to the total amount of atoms.

[Abrasive liquid composition]
The present invention relates to a polishing liquid composition (hereinafter, also referred to as "polishing liquid composition of the present invention") containing the composite abrasive grains of the present invention and an aqueous medium.

The content of the composite abrasive grains of the present invention in the polishing liquid composition of the present invention is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and 0.2% by mass from the viewpoint of improving the polishing speed. % Or more is more preferable, and from the same viewpoint, 5% by mass or less is preferable, 2.5% by mass or less is more preferable, and 1% by mass or less is further preferable.

Examples of the aqueous medium contained in the polishing liquid composition of the present invention include water and a mixture of water and a solvent soluble in water. Examples of the solvent soluble in water include lower alcohols such as methanol, ethanol and isopropanol, and ethanol is preferable from the viewpoint of safety in the polishing step. The water-based medium is more preferably composed of water such as ion-exchanged water, distilled water, and ultrapure water from the viewpoint of improving the quality of the semiconductor substrate. As for the content of the aqueous medium in the polishing liquid composition of the present invention, assuming that the total mass of the composite abrasive grains of the present invention, the following optional components and the aqueous medium is 100% by mass, the composite abrasive grains of the present invention and the optional components described later are used. Can be the remainder excluding.

The polishing liquid composition of the present invention has, as optional components, a pH adjuster, a polishing aid, an acid, an oxidizing agent, a heterocyclic aromatic compound, an aliphatic amine compound, an alicyclic amine compound, a saccharide compound, and a nonionic interface. An activator, a thickener, a dispersant, a rust preventive, and the like may be contained, but from the viewpoint of improving the polishing rate, it is preferable that the compound having an anionic group is not contained. Examples of the anionic group include a carboxylic acid group, a sulfonic acid group, a sulfate ester group, a phosphoric acid ester group, a phosphonic acid group and the like.

Examples of the pH adjuster include acidic compounds and alkaline compounds. Examples of the acidic compound include inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid; organic acids such as acetic acid, oxalic acid, citric acid and malic acid; and the like. Among them, at least one selected from hydrochloric acid, nitric acid and acetic acid is preferable, and at least one selected from hydrochloric acid and acetic acid is more preferable from the viewpoint of versatility. Examples of the alkaline compound include inorganic alkaline compounds such as ammonia and potassium hydroxide; organic alkaline compounds such as alkylamine and alkanolamine; and the like. Among them, at least one selected from ammonia and alkylamine is preferable, and ammonia is more preferable, from the viewpoint of improving the quality of the semiconductor substrate.

Examples of the nonionic surfactant include nonionic polymers such as polyacrylamide, polyoxyalkylene alkyl ether, polyoxyethylene distyrene phenyl ether and the like.

The polishing liquid composition of the present invention can be produced by a production method including a step of blending the composite abrasive grains of the present invention, an aqueous medium, and an arbitrary component by a known method. For example, the polishing liquid composition of the present invention may be made by blending at least the composite abrasive grains of the present invention and an aqueous medium. In the present invention, "blending" includes mixing the composite abrasive grains of the present invention, an aqueous medium, and optionally the above-mentioned optional components at the same time or in order. The order of mixing is not particularly limited. The formulation can be performed using, for example, a mixer such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill. The blending amount of each component in the method for producing the polishing liquid composition of the present invention can be the same as the content of each component in the polishing liquid composition of the present invention described above.

The embodiment of the polishing liquid composition of the present invention may be a so-called one-component type in which all the components are premixed and supplied to the market, or a so-called two-component type in which all the components are mixed at the time of use. There may be.

From the viewpoint of improving the polishing speed, the pH of the polishing liquid composition of the present invention is preferably 3.5 or more, more preferably 4 or more, further preferably 4.5 or more, preferably 10 or less, and more preferably 9 or less. It is preferable, and 8 or less is more preferable. In the present invention, the pH of the polishing liquid composition is a value at 25 ° C., which is a value measured using a pH meter. Specifically, the pH of the polishing liquid composition of the present invention can be measured by the method described in Examples.

The "content of each component in the polishing liquid composition" of the present invention means the content of each component at the time when the polishing liquid composition is used for polishing. The polishing liquid composition of the present invention may be stored and supplied in a concentrated state as long as its stability is not impaired. In this case, it is preferable in that the manufacturing / transportation cost can be reduced. Then, this concentrated liquid can be appropriately diluted with the above-mentioned aqueous medium and used in the polishing step, if necessary. The dilution ratio is preferably 5 to 100 times.

Examples of the polishing target of the polishing liquid composition of the present invention include a silicon oxide film. Therefore, the polishing liquid composition of the present invention can be suitably used for polishing a substrate to be polished containing a silicon oxide film to be polished, for example, a silicon oxide film performed in a step of forming an element separation structure of a semiconductor substrate. Can be suitably used for polishing.

[Abrasive liquid kit]
The present invention relates to a kit for producing a polishing liquid composition, which comprises a composite abrasive grain dispersion liquid in a container in which a dispersion liquid containing the composite abrasive grains of the present invention is stored in a container. According to the polishing liquid kit of the present invention, it is possible to provide a polishing liquid kit capable of obtaining a polishing liquid composition capable of improving the polishing speed.

As one embodiment of the polishing liquid kit of the present invention, for example, an abrasive grain slurry (first liquid) in which the composite abrasive grains of the present invention are dispersed in an aqueous medium, and a solution containing an additive and an aqueous medium (second liquid). ) In a state where they are not mixed with each other, and these are mixed at the time of use and diluted with an aqueous medium if necessary, and examples thereof include a polishing liquid kit (two-component polishing liquid composition). Examples of the additive include a polishing aid, an acid, an oxidizing agent, a heterocyclic aromatic compound, an aliphatic amine compound, an alicyclic amine compound, a saccharide compound and the like. The first liquid and the second liquid may each contain a pH adjuster, a thickener, a dispersant, a rust preventive, a basic substance, a polishing rate improver and the like, if necessary. The first liquid and the second liquid may be mixed before being supplied to the surface to be polished, or may be separately supplied and mixed on the surface of the substrate to be polished.

[Manufacturing method of semiconductor substrate]
The present invention is a method for manufacturing a semiconductor substrate, which comprises a step of polishing a substrate to be polished using the polishing liquid composition of the present invention (hereinafter, also referred to as a “polishing step using the polishing liquid composition of the present invention”). Hereinafter, it is also referred to as “a method for manufacturing a semiconductor substrate of the present invention”). According to the method for manufacturing a semiconductor substrate of the present invention, by using the polishing liquid composition of the present invention, the polishing speed in the polishing step can be improved, so that the effect that the semiconductor substrate can be efficiently manufactured can be achieved.

As a specific example of the method for manufacturing a semiconductor substrate of the present invention, first, a silicon nitride layer is grown on the surface of a silicon substrate by exposing it to oxygen in an oxidation furnace, and then silicon nitride (Si) is placed on the silicon dioxide layer. ₃ N ₄ ) A polishing stopper film such as a film or a polysilicon film is formed by, for example, a CVD method (chemical vapor deposition method). Next, a photolithography technique is applied to a substrate including a silicon substrate and a polishing stopper film arranged on one main surface side of the silicon substrate, for example, a substrate in which a polishing stopper film is formed on a silicon dioxide layer of a silicon substrate. Is used to form a trench. Next, for example, a silicon oxide (SiO ₂ ) film, which is a film to be polished for trench embedding, is formed by a CVD method using silane gas and oxygen gas, and the polishing stopper film is covered with the film to be polished (silicon oxide film). Obtain a substrate to be polished. By forming the silicon oxide film, the trench is filled with silicon oxide of the silicon oxide film, and the opposite surface of the polishing stopper film on the silicon substrate side is covered with the silicon oxide film. The opposite surface of the surface of the silicon oxide film thus formed on the silicon substrate side has a step formed corresponding to the unevenness of the lower layer. Next, the silicon oxide film is polished by the CMP method until at least the opposite surface of the surface of the polishing stopper film on the silicon substrate side is exposed, and more preferably, the surface of the silicon oxide film and the surface of the polishing stopper film are flush with each other. Polish the silicon oxide film until it becomes. The polishing liquid composition of the present invention can be used in the step of performing polishing by this CMP method.

In polishing by the CMP method, the surface of the substrate to be polished and the polishing pad are in contact with each other, and the polishing liquid composition of the present invention is supplied to these contact portions while the substrate to be polished and the polishing pad are relatively moved. This flattens the uneven portion of the surface of the substrate to be polished. In the method for manufacturing a semiconductor substrate of the present invention, another insulating film may be formed between the silicon dioxide layer of the silicon substrate and the polishing stopper film, or the film to be polished (for example, a silicon oxide film) and the polishing stopper. Another insulating film may be formed between the film (for example, a silicon nitride film).

In the polishing step using the polishing liquid composition of the present invention, the polishing pad was provided with a polishing pad having a polishing pad rotation speed of, for example, 30 to 200 r / min, and a polishing substrate rotation speed of, for example, 30 to 200 r / min. The polishing load set in the polishing apparatus can be set to, for example, 20 to 500 g weight / cm ² , and the supply rate of the polishing liquid composition can be set to, for example, 10 to 500 mL / min or less. When the polishing liquid composition is a two-component polishing liquid composition, the polishing speed of each of the film to be polished and the polishing stopper film can be adjusted by adjusting the supply speed (or supply amount) of each of the first liquid and the second liquid. In addition, the polishing speed ratio (polishing selectivity) between the film to be polished and the polishing stopper film can be adjusted.

In the polishing step using the polishing liquid composition of the present invention, the polishing rate of the film to be polished (for example, silicon oxide film) is preferably 1000 Å / min or more, more preferably 3000 Å / min or more from the viewpoint of improving productivity. More preferably, it is 5000 Å / min or more.

In the polishing step using the polishing liquid composition of the present invention, the polishing speed of the polishing stopper film (for example, silicon nitride film) is preferably 500 Å / min or less from the viewpoint of improving polishing selectivity and shortening the polishing time. It is more preferably 300 Å / min or less, still more preferably 150 Å / min or less.

In the polishing process using the polishing liquid composition of the present invention, the polishing rate ratio (polishing rate of the film to be polished / polishing rate of the polishing stopper film) is preferably 5 or more, preferably 10 or more, from the viewpoint of shortening the polishing time. Is more preferable, 20 or more is further preferable, and 40 or more is even more preferable. In the present disclosure, the polishing selectivity can be evaluated by the ratio of the polishing rate of the film to be polished to the polishing rate of the polishing stopper film (polishing rate of the film to be polished / polishing rate of the polishing stopper film), and the polishing selectivity is high. Means that the polishing rate ratio is large.

[Polishing method]
The present invention relates to a substrate polishing method (hereinafter, also referred to as the polishing method of the present invention) including a polishing step using the polishing liquid composition of the present invention, and preferably to a substrate polishing method for manufacturing a semiconductor substrate. .. By using the polishing method of the present invention, the polishing speed in the polishing process can be improved, so that the effect that the semiconductor substrate can be efficiently manufactured can be achieved. The specific polishing method and conditions can be the same as the above-described method for manufacturing the semiconductor substrate of the present invention.

[Manufacturing method of semiconductor devices]
The present invention relates to, in one aspect, a method for manufacturing a semiconductor device, which comprises a polishing step using the polishing liquid composition of the present invention. According to the method for manufacturing a semiconductor device of the present invention, the effect of efficiently obtaining a semiconductor substrate and improving the productivity of the semiconductor device can be achieved. The specific polishing method and conditions of the polishing step can be the same as the above-mentioned method for manufacturing the semiconductor substrate of the present invention.

In one aspect, the method for manufacturing a semiconductor device of the present invention includes a step of polishing an uneven stepped surface of a silicon oxide film using the polishing liquid composition of the present invention. The semiconductor device is a semiconductor storage device in which recording elements are three-dimensionally arranged, and includes a step of forming the silicon oxide film between horizontally adjacent recording elements and so as to cover the recording elements. The uneven step surface of the silicon oxide film formed in the step has an uneven step corresponding to the unevenness of the surface covered by the silicon oxide film. The width of the convex portion of the silicon oxide film is, for example, 0.5 μm or more and 5000 μm or less, preferably 10 μm or more and 3500 μm or less, and the width of the concave portion is, for example, 0.5 μm or more and 10000 μm or less, preferably 10 μm. It is 6000 μm or less.

Hereinafter, the present disclosure will be described in more detail by way of examples, but these are exemplary and the present disclosure is not limited to these examples.

1. 1. Measurement of each parameter [Aspect ratio of abrasive grains, long side and short side]
The aspect ratio of the abrasive grains was measured by the following method. A dispersed slurry in which abrasive grains were dispersed in ion-exchanged water so that the abrasive grain concentration was 0.01% by mass was dropped onto a grid and air-dried. It was observed with a scanning electron microscope (FE-SEM). The maximum length of the particles in the obtained image is defined as the "long side", the maximum length in the direction orthogonal to the "long side" is measured as the "short side", and the ratio (long side / short side) is calculated. The average values for each of 100 pieces are shown in Table 1 as the aspect ratio, the long side, and the short side.

[Exposure amount of {100} surface]
The exposure amount of the {100} surface of the abrasive grains was measured by the following method. A dispersed slurry in which abrasive grains were dispersed in ion-exchanged water so that the abrasive grain concentration was 0.01% by mass was dropped onto a grid and air-dried. It was observed with a scanning electron microscope (FE-SEM). With the square portion of the particle surface in the obtained image as the {100} plane, the ratio of the area of the square portion to the surface area of each of the 100 particles in the FE-SEM observation image was calculated, and the average value was {100}. } Calculated as the amount of surface exposure and shown in Table 1.
The shape of the particles in the FE-SEM observation image is a shape observed from only one direction, but here, the shape of the particles is assumed to be a symmetrical shape, that is, the shape is observed from only one direction by the FE-SEM. The above exposure amount was calculated on the assumption that the shape of the particles (front surface shape) and the shape of the particles observed from the opposite direction to the one direction (back surface shape) are the same.

[Amount of water produced by abrasive grains]
The amount of water produced by the abrasive grains at 300 ° C. or lower as measured by the temperature rise reduction method (TPR) is calculated as follows.
<Preparation of measurement sample>
The abrasive grain water dispersion in which the abrasive grains are dispersed in ion-exchanged water is dried with hot air at 120 ° C. for 3 hours, and if necessary, crushed in an agate mortar to obtain a powdery composite abrasive grain sample. The obtained sample is dried at 80 ° C. for 3 hours, immediately after that, 0.1 g is weighed and placed in a sample tube (reaction chamber).
Then, pure argon gas is supplied to the reaction chamber at a flow rate of 50 cc / min. With pure argon gas supplied, 0.1 g of the sample placed in the reaction chamber was heated from 25 ° C to 300 ° C over 50 minutes at a constant heating rate, kept at 300 ° C for 60 minutes, and up to 100 ° C. Allow to cool naturally and hold at 100 ° C. for 10 minutes.
<Measurement of water production by temperature reduction method (TPR)>
The amount of water produced by TPR is measured under the following conditions using a temperature raising reduction device (“BELCAT-B” manufactured by Nippon Bell Co., Ltd.).
While supplying a mixed gas of 5% by volume hydrogen gas and 95% by volume argon gas to the reaction chamber at a flow rate of 30 cc / min, the temperature rise rate was set to 5 ° C./min, and the sample was sampled from 100 ° C. to 950. The temperature rises to ° C. Then, during this temperature rise, the amount of water produced per unit weight A (mmol) generated by the reduction of tetravalent cerium to trivalent cerium in the temperature range up to 300 ° C. by the gas analyzer "BELMass". / G) is detected. Here, in the detection of the amount of water produced A, the amount of water produced (mmol / g) having a continuous series of peaks of 5 mmol / g or more when the relationship of the amount of water produced A (mmol / g) with respect to the measured temperature is taken. Detected as g), the amount of water produced A (mmol / g) derived from the baseline shall be treated as 0 mmol / g. Due to the measurement principle, a plurality of water production amounts A (mmol / g) may be observed at the same temperature. In this case, the average value of the plurality of water production amounts A (mmol / g) at the same temperature is used. The amount of water produced with respect to the measured temperature is A (mmol / g).
Then, by dividing the detected water production amount A (mmol / g) by the BET specific surface area B (m ² / g) measured by the following BET method, the water production amount A / B (mmol) per unit surface area is obtained. / M ² )), that is, the amount of water produced at 300 ° C. or lower as measured by TPR is determined.

[BET specific surface area of abrasive grains]
The abrasive grain dispersion liquid in which the abrasive grains are dispersed in ion-exchanged water is dried with hot air at 120 ° C. for 3 hours, and if necessary, crushed in an agate mortar to obtain a powdery cerium oxide particle sample. Immediately before measuring the BET specific surface area, the obtained sample was dried at 120 ° C. for 15 minutes, and the BET specific surface area (m) was measured by the BET method using a micromeric automatic specific surface area measuring device "Flowsorb III2305" (manufactured by Shimadzu Corporation). ² / g) is measured.

[PH of polishing liquid composition]
The pH value of the polishing liquid composition at 25 ° C. is a value measured using a pH meter (“HM-30G” manufactured by Toa Denpa Kogyo Co., Ltd.), and the electrode of the pH meter is immersed in the polishing liquid composition. It is a numerical value after minutes.

2. 2. Manufacturing Method of Composite Abrasive Grains or Details thereof [Manufacturing Method of Composite Abrasive Grains of Example 2]
1.560 g (3.6 mmol) of cerium nitrate (III) hexahydrate and 0.213 g (0.4 mmol) of zirconium oxynitrate dihydrate were dissolved in ion-exchanged water: 5 mL, respectively. Next, 17.0 g (0.425 mol) of sodium hydroxide was dissolved in 70 mL of ion-exchanged water (about 6 mol / L). The above aqueous solution containing cerium nitrate and zirconium oxynitrite was added to the aqueous sodium hydroxide solution with stirring, and the stirring was continued for 30 minutes or more to form a precipitate. After that, the slurry containing the precipitate is transferred to a 100 mL Teflon container, the Teflon container is placed in a stainless steel reaction container (autoclave manufactured by San-Ai Kagaku), sealed, and the stainless steel container is placed in a blower dryer at 180 ° C. for 24 hours. Hydrothermal treatment was performed. After the completion of the hydrothermal treatment, the precipitate was cooled to room temperature, the precipitate was thoroughly washed with ion-exchanged water, and then dried in a blower dryer at 100 ° C. to obtain a powder (Zr-containing ceria abrasive grains of Example 1). ..
As a result of analyzing the obtained dry powder of the Zr-containing ceria abrasive grains of Example 1 by X-ray diffraction, the peak of zirconia alone near 33 ° was not observed, and the peak was shifted to a higher angle side than the theoretical peak of ceria. A peak was observed. Moreover, as a result of investigating the composition ratio of Ce and Zr using X-ray photoelectron spectroscopy (XPS), the composition ratio of Ce and Zr was 90:10 (mol ratio).

[Manufacturing method of composite abrasive grains of Example 1]
Except for changing the amounts of cerium nitrate (III) hexahydrate and zirconium oxynitrate dihydrate used so that the Ce: Zr ratio is 75:25 (mol ratio), [Example 2] Method for producing composite abrasive grains], Zr-containing cerium abrasive grains of Example 1 were obtained.

[Manufacturing method of composite abrasive grains of Example 3]
Except for changing the amounts of cerium nitrate (III) hexahydrate and zirconium oxynitrate dihydrate used so that the Ce: Zr ratio is 85:15 (mol ratio), [Example 2] Method for producing composite abrasive grains], Zr-containing ceria abrasive grains of Example 3 were obtained.

[Method for manufacturing composite abrasive grains of Example 4]
Except for changing the amounts of cerium nitrate (III) hexahydrate and zirconium oxynitrate dihydrate used so that the Ce: Zr ratio is 80:20 (mol ratio), [Example 2] Method for producing composite abrasive grains], Zr-containing ceria abrasive grains of Example 4 were obtained.

[Method for manufacturing composite abrasive grains of Example 5]
Except for changing the amounts of cerium nitrate (III) hexahydrate and zirconium oxynitrate dihydrate used so that the Ce: Zr ratio is 70:30 (mol ratio), [Example 2] Method for producing composite abrasive grains], Zr-containing ceria abrasive grains of Example 5 were obtained.

[Manufacturing method of composite abrasive grains of Comparative Example 1]
Except for changing the amounts of cerium nitrate (III) hexahydrate and zirconium oxynitrate dihydrate used so that the Ce: Zr ratio is 50:50 (mol ratio), [Example 2] Method for producing composite abrasive grains], Zr-containing ceria abrasive grains of Comparative Example 1 were obtained.

[Manufacturing method of composite abrasive grains of Comparative Example 2]
Except for changing the amounts of cerium nitrate (III) hexahydrate and zirconium oxynitrate dihydrate used so that the Ce: Zr ratio is 60:40 (mol ratio), [Example 2] Method for producing composite abrasive grains], Zr-containing ceria abrasive grains of Comparative Example 2 were obtained.

[Manufacturing method of composite abrasive grains of Comparative Example 3]
Except that the amounts of cerium nitrate (III) hexahydrate and zirconium oxynitrate dihydrate used were changed so that the Ce: Zr ratio was 97.6: 2.4 (mol ratio). Method for producing composite abrasive grains of Example 2], Zr-containing cerium abrasive grains of Comparative Example 3 were obtained.

[Manufacturing method of composite abrasive grains of Comparative Example 4]
The medium volume diameter obtained by wet pulverizing the calcined product A (Ce _0.75 Zr _0.25 O ₂ particles) with a bead mill in water to which a dispersant (ammonium polyacrylate, weight average molecular weight 6000) was added. A slurry (Ce _0.75 Zr _0.25 O ₂ particles: 25% by weight) of 150 nm Ce _0.75 Zr _0.25 O ₂ particles (crushed Zr-containing ceria abrasive grains) was prepared. The fired product A was obtained by firing unfired Ce _0.75 Zr _0.25 O ₂ particles (trade name: Actaries9320, manufactured by Rhodia) at 1160 ° C. for 6 hours in a continuous firing furnace. The fired product A was obtained by using a cerium (IV) compound and a zirconium (IV) compound as raw materials.

[Manufacturing method of abrasive grains of Comparative Example 5]
The abrasive grains of Comparative Example 5 were treated with 2 kg of commercially available cerium carbonate hydrate in an oven at 100 ° C. humidified with steam of pure water for 8 hours, placed in an alumina container, and placed in an alumina container at 830 ° C. for 2 hours in the air. Ceria abrasive grains adjusted by baking were used.

[Manufacturing method of abrasive grains of Comparative Example 6]
Except that the amount of zirconium oxynitrate dihydrate used was changed without using cerium (III) nitrate hexahydrate so that the ratio of Ce: Zr was 0: 100 (mol ratio). Similar to [Method for producing composite abrasive grains of Example 2], Zr abrasive grains of Comparative Example 6 were obtained.

3. 3. Preparation of polishing liquid composition (Examples 1 to 5 and Comparative Examples 1 to 6)
Abrasive grains (0.5% by mass) of Examples 1 to 5 and Comparative Examples 1 to 6, a pH adjuster (small amount) and an aqueous medium (ultrapure water) (remaining portion) were mixed, if necessary. Polishing solution compositions of Examples 1 to 5 and Comparative Examples 1 to 6 having a pH of 4.5 at 25 ° C. were obtained. Ammonia or hydrochloric acid was used as the pH adjuster.

4. Evaluation of Polishing Liquid Compositions (Examples 1 to 5 and Comparative Examples 1 to 6) [Preparation of Test Pieces]
A 40 mm × 40 mm square piece was cut out from a silicon wafer having a silicon oxide film having a thickness of 2,000 nm formed on one side of the silicon wafer by the TEOS-plasma CVD method to obtain a silicon oxide film test piece.

[Measurement of polishing speed of silicon oxide film (film to be polished)]
As a polishing device, "TR15M-TRK1" manufactured by Technorise Co., Ltd. having a surface plate diameter of 380 mm was used. As the polishing pad, a rigid urethane pad "IC-1000 / Suba400" manufactured by Nitta Haas Co., Ltd. was used. The polishing pad was attached to the surface plate of the polishing device. The test piece was set on the holder, and the holder was placed on the polishing pad so that the surface of the test piece on which the silicon oxide film was formed was facing down (so that the silicon oxide film faced the polishing pad). Further, the weight was placed on the holder so that the load applied to the test piece was 300 g weight / cm ² . While dropping the polishing liquid composition at a rate of 50 mL / min on the center of the surface plate to which the polishing pad is attached, rotate each of the surface plate and the holder in the same rotation direction at 90 r / min for 1 minute to make silicon oxide. The membrane test piece was polished. After polishing, it was washed with ultrapure water and dried, and the silicon oxide film test piece was used as a measurement target by the optical interferometry film thickness measuring device described later.

Before and after polishing, the film thickness of the silicon oxide film was measured using a light interferometry film thickness measuring device (“Lambda Ace VM-1000” manufactured by Dainippon Screen Co., Ltd.). The polishing rate of the silicon oxide film was calculated by the following formula, and is a relative value when the polishing rate of Comparative Example 4 was 100, and is shown in Table 1 below.
Polishing speed of silicon oxide film (Å / min)
= [Silicon oxide film thickness before polishing (Å) -Silicon oxide film thickness after polishing (Å)] / Polishing time (minutes)

As shown in Table 1, the content of the metal atom A in the composite abrasive grains is 8 mol% or more and 37 mol% or less with respect to the total amount (100 mol%) of the cerium atom and the metal atom A. When the polishing liquid compositions of Examples 1 to 5 containing the composite abrasive grains having an aspect ratio of the composite abrasive grains of 2.0 or more and 100 or less are used, when the polishing liquid compositions of Comparative Examples 1 to 6 are used. Compared with, the polishing speed was improved.

The composite abrasive grains of the present invention are useful in a method for manufacturing a semiconductor substrate for high density or high integration.

Claims (10)

It is a composite abrasive grain in which a part of the cerium atom in the cerium oxide particles is replaced with a tetravalent metal atom other than the cerium atom.
The content of the metal atom in the composite abrasive grains is 8 mol% or more and 37 mol% or less with respect to the total amount of the cerium atom and the metal atom.
The aspect ratio is 3 or more and 20 or less ,
The amount of water produced at 300 ° C. or lower as measured by the temperature-reducing method (Temperature-Programmed-Reaction) is 8 mmol / m ² or more per unit surface area of the composite abrasive grains.
Composite abrasive grains. The composite abrasive grain according to claim 1, wherein the short side of the composite abrasive grain is 10 nm or more and less than 50 nm. The composite abrasive grain according to claim 1 or 2, wherein the long side of the composite abrasive grain is 60 nm or more and 1000 nm or less. The composite abrasive grain according to any one of claims 1 to 3, wherein the metal atom is at least one atom selected from manganese, titanium and zirconium. The composite abrasive grain according to any one of claims 1 to 4, wherein the exposure amount of the {100} surface on the composite abrasive grain surface is 3% or more and 90% or less. A polishing liquid composition containing the composite abrasive grains according to any one of claims 1 to 5 and an aqueous medium. A method for manufacturing a semiconductor substrate, which comprises a step of polishing the substrate to be polished using the polishing liquid composition according to claim 6 . A method for polishing a substrate, which comprises a step of polishing the substrate to be polished using the polishing liquid composition according to claim 6 . A method for manufacturing a semiconductor device, which comprises a step of polishing a substrate to be polished using the polishing liquid composition according to claim 6 . A step of mixing an aqueous solution containing cerium, an aqueous solution containing a tetravalent metal atom other than a cerium atom, and an aqueous solution containing an alkaline agent to form a precipitate.
Next, the step of hydrothermally treating the produced precipitate at 100 ° C. or higher and 300 ° C. or lower for 6 hours or longer and 120 hours or lower is included.
The content of the metal atom in the composite abrasive grain is 8 mol% or more and 37 mol% or less, and the aspect ratio is 3 or more and 20 or less with respect to the total amount of the cerium atom and the metal atom.
A method for producing composite abrasive grains, wherein the amount of water produced at 300 ° C. or lower measured by the temperature-heating reduction method (Temperature-Programmed-Reaction) is 8 mmol / m ² or more per unit surface area of the composite abrasive grains.