JP2001308044A - Oxide cerium polishing agent and polishing method for substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxide cerium polishing agent, which has a proper dispersing property, suppresses generation of polishing damage and can flatly polish a surface to be polished of such an oxide silicon insulating film and so on, and a polishing method for a substrate in which the substrate for a semiconductor, having a high quality and a high reliability can be obtained easily and at a proper yield ratio. SOLUTION: The polishing method for a substrate has the feature of providing with an oxide cerium polishing agent made of a slurry having a range of weight ratio of oxide cerium and a dispersing agent which attaches with oxide cerium which is in the range of 1 to 0.002 or 1 to 0.005 and polishing the prescribed substrate by the oxide cerium polishing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a cerium oxide abrasive and a method for polishing a substrate.

[0002]

2. Description of the Related Art Conventionally, in the manufacturing process of a semiconductor device,
As a chemical mechanical polishing agent for flattening an inorganic insulating film layer such as a silicon oxide 2 insulating film formed by a method such as plasma-CVD or low pressure-CVD, a fumed silica-based polishing agent is generally studied. I have. Fumed silica-based abrasives are produced by growing silica particles by a method such as thermal decomposition of silicic acid tetrachloride and adjusting the pH with an alkaline solution containing no alkali metal such as ammonia. However, such a polishing agent does not have a sufficient polishing rate for the inorganic insulating film, and there is a technical problem of a low polishing rate for practical use.

On the other hand, cerium oxide abrasives have been used for polishing the glass surface for photomasks. Cerium oxide particles have lower hardness than silica particles and alumina particles,
Therefore, it is useful for finish mirror polishing because the polishing surface is hardly damaged. Cerium oxide also has chemically active properties, as is known as a strong oxidizing agent. Taking advantage of this advantage, application to a chemical mechanical polishing agent for an insulating film is useful.

However, when a cerium oxide abrasive for polishing a glass surface for a photomask is used as it is for polishing an inorganic insulating film, the primary particle diameter is large, and polishing scratches that can be visually observed are formed on the surface of the insulating film. Further, the cerium oxide particles have a large theoretical specific gravity of 7.2, and thus easily settle. As a result, the abrasive supply concentration unevenness during polishing,
Problems such as clogging in the supply pipe occur.

[0005]

The invention according to claims 1 to 5 has good dispersibility, suppresses the occurrence of polishing scratches, and makes it possible to flatten a surface to be polished such as a silicon oxide insulating film. A cerium abrasive is provided. The invention according to claims 6 to 7 provides a substrate polishing method capable of easily obtaining a high-quality and high-reliability semiconductor substrate with good yield.

[0006]

According to the present invention, a weight ratio of cerium oxide to a dispersant attached to cerium oxide is 1 to 0.0.
Cerium oxide abrasive comprising a slurry ranging from 02 to 1 to 0.005. The present invention also relates to the cerium oxide abrasive, wherein the slurry contains a dispersant that is not attached to cerium oxide. The present invention also relates to the cerium oxide abrasive, wherein the slurry contains water as a medium.

Further, in the present invention, the dispersant is at least one compound selected from a water-soluble organic polymer, a water-soluble anionic surfactant, a water-soluble nonionic surfactant and a water-soluble amine. Cerium oxide abrasive. The present invention also relates to the cerium oxide abrasive having a pH of 7 to 10.

The present invention also relates to a method for polishing a substrate, comprising polishing a predetermined substrate with the cerium oxide abrasive. The present invention also relates to the above-mentioned substrate polishing method, wherein the predetermined substrate is a semiconductor element having a silicon oxide insulating film formed thereon.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Generally, cerium oxide is a carbonate,
It is obtained by calcining cerium compounds such as sulfates and oxalates. The silicon oxide insulating film formed by a TEOS-CVD method or the like has a large primary particle diameter and a small crystal distortion, that is, a high crystallinity, so that high-speed polishing can be performed, but polishing scratches tend to occur. . Therefore, the cerium oxide particles used in the present invention are produced without increasing crystallinity. Further, since it is used for polishing a semiconductor chip, the content of alkali metals and halogens is preferably suppressed to 1 ppm or less.

The abrasive of the present invention is of high purity, and contains Na,
K, Si, Mg, Ca, Zr, Ti, Ni, Cr, Fe
Is 1 ppm or less, and Al is 10 ppm or less.

In the present invention, a firing method can be used as a method for producing cerium oxide particles. However, in order to produce particles that do not cause polishing scratches, low-temperature firing that does not increase the crystallinity as much as possible is preferable. Since the oxidation temperature of the cerium compound is 300 ° C., the firing temperature is 600 ° C. or more and 9 ° C.
00 ° C or lower is preferred. Cerium carbonate over 600 ℃ 9
It is preferable to bake in air at a temperature of 00 ° C. or lower for 60 to 120 minutes.

The calcined cerium oxide can be pulverized by dry pulverization such as a jet mill or wet pulverization such as a bead mill. The jet mill is described, for example, in Chemical Industry Transactions, Vol. 6, No. 5, (1980), pp. 527-532.

The cerium oxide particles obtained by pulverizing the calcined cerium oxide by dry pulverization such as a jet mill or the like include particles having a small primary particle (crystallite) size and polycrystals not pulverized to the primary particle (crystallite) size. This polycrystal is different from an aggregate in which primary particles (crystallites) are re-agglomerated, and is composed of two or more primary particles (crystallites) and has a crystal grain boundary. When polishing is performed with an abrasive containing a polycrystal having a crystal grain boundary, it is presumed that the surface is destroyed due to stress during polishing and an active surface is generated, and the surface to be polished such as a silicon oxide insulating film is polished at high speed without damage. It is thought that it contributes to doing.

[0014] The cerium oxide slurry in the present invention comprises:
It is obtained by dispersing an aqueous solution containing cerium oxide particles produced by the above method or a composition comprising cerium oxide particles recovered from this aqueous solution, water and, if necessary, a dispersant. Here, the concentration of the cerium oxide particles is not limited, but is preferably in the range of 0.5 to 10% by weight from the viewpoint of easy handling of the suspension (abrasive). further,
In order to obtain storage stability, a range of 1 to 5% by weight is preferable.

As the dispersant, a water-soluble organic polymer,
There are water-soluble anionic surfactants, water-soluble nonionic surfactants and water-soluble amines. For example, there is a copolymer of ammonium acrylate and methyl acrylate, particularly a copolymer of ammonium acrylate and methyl acrylate having a weight average molecular weight of 1,000 to 20,000. The weight average molecular weight is a value measured by gel permeation chromatography and converted to standard polystyrene.

The amount of the dispersant added is preferably in the range of 0.01 to 5 parts by weight based on 100 parts by weight of the cerium oxide particles in view of the dispersibility of the particles in the slurry and the anti-settling property. In order to increase the particle size, it is preferable to put the particles into a disperser at the same time as the particles are dispersed.

As a method for dispersing these cerium oxide particles in water, an ultrasonic disperser, a homogenizer, a ball mill or the like can be used in addition to the usual dispersion treatment using a stirrer. In order to disperse cerium oxide particles on the order of submicron, it is preferable to use a wet disperser such as a ball mill, a vibrating ball mill, a planetary ball mill, and a medium stirring mill. When it is desired to increase the alkalinity of the slurry, an alkaline substance not containing metal ions such as aqueous ammonia can be added during or after the dispersion treatment.

When a copolymer of ammonium acrylate and methyl acrylate is used as the dispersant contained in the slurry of the present invention, the dispersant is used in an amount of 0.01 to 5.00 parts by weight based on 100 parts by weight of the cerium oxide particles. It is preferably added, and its weight average molecular weight is preferably from 1,000 to 20,000. The molar ratio of ammonium acrylate to methyl acrylate is preferably from 0.1 to 0.9. If the copolymer of ammonium acrylate and methyl acrylate is less than 0.01 part by weight with respect to 100 parts by weight of cerium oxide particles, sedimentation is easy, and if it is more than 5 parts by weight, the particle size distribution due to reagglomeration tends to change over time. . Further, the weight average molecular weight is 200
If it exceeds 00, the particle size distribution tends to change with time due to re-aggregation.

The median diameter of the cerium oxide particles having crystal grain boundaries dispersed in the slurry of the present invention is 60 to 1500 nm.
Are preferable, and the median value of the primary particle (crystallite) diameter is 30 to 2
50 nm is preferred.

If the median diameter of cerium oxide particles having crystal grain boundaries is less than 60 nm, or the median diameter of primary particles (crystallites) is less than 30 nm, a surface to be polished such as a silicon oxide insulating film is polished at high speed. When the median diameter of cerium oxide particles having crystal grain boundaries exceeds 1500 nm, or the median diameter of primary particles (crystallites) exceeds 250 nm, it is difficult to cover silicon oxide insulating films and the like. Scratches are likely to occur on the polished surface. If the maximum value of the diameter of the cerium oxide particles having a crystal grain boundary exceeds 3000 nm, a surface to be polished such as a silicon oxide insulating film is likely to be damaged. The content of the cerium oxide particles having a crystal grain boundary is preferably 5 to 100% by volume of the total cerium oxide particles, and when the content is less than 5% by volume, a surface to be polished such as a silicon oxide insulating film is easily damaged.

In the above cerium oxide particles, the maximum diameter of the primary particles (crystallites) is preferably 600 nm or less, and the diameter of the primary particles (crystallites) is preferably 10 to 600 nm. If the primary particles (crystallites) exceed 600 nm, scratches tend to occur, and if it is less than 10 nm, the polishing rate tends to decrease.

The pH of the slurry of the present invention is preferably from 7 to 10 and more preferably from 8 to 9.

The amount of cerium oxide attached to the dispersant in the present invention is determined, for example, by the difference between the amount of dispersant in the slurry and the amount of dispersant not attached to cerium oxide in the slurry. The amount of the dispersant in the slurry can be determined by the difference between the amount of solid content obtained by removing water in the slurry by heating or vacuum drying and the weight of cerium oxide. The amount of the dispersing agent not adhering to the cerium oxide in the slurry is obtained by first separating the slurry into cerium oxide and the supernatant by a method such as centrifugation, and removing the water in the supernatant by a method such as heating or vacuum drying. It is a quantity.

The weight ratio of cerium oxide to the dispersant adhered to cerium oxide in the slurry of the present invention is in the range of 1: 0.002 to 1: 0.005. , Flatness, productivity, workability, etc. are inferior. This weight ratio is preferably in the range of 1: 0.0023 to 1: 0.049.

As a method for forming an inorganic insulating film using the cerium oxide abrasive of the present invention, there are a constant pressure CVD method, a plasma CVD method and the like. In forming a silicon oxide insulating film by a constant-pressure CVD method, monosilane: SiH _{4 is} used as a Si source, and oxygen: O ₂ is used as an oxygen source. This SiH ₄ —O ₂ -based oxidation reaction is obtained by performing the reaction at a low temperature of about 400 ° C. or less. When doping phosphorus: P in order to planarize the surface by high-temperature reflow, SiH ₄ —O ₂ —P
It is preferable to use an H ₃ -based reaction gas.

The plasma CD method has an advantage that a chemical reaction requiring a high temperature can be performed at a low temperature under normal thermal equilibrium.
The plasma generation method includes two types, a capacitive coupling type and an inductive coupling type. As a reaction gas, Si is used as a Si source.
H ₄ , a SiH ₄ —N ₂ O-based gas using N ₂ O as an oxygen source and tetraethoxysilane (TEOS) are used as a TEOS-O ₂ -based gas (TEOS-plasma CVD) used as a Si source.
Method). The substrate temperature is preferably in the range of 250 ° C. to 400 ° C., and the reaction pressure is preferably in the range of 67 to 400 Pa. As described above, the silicon oxide insulating film of the present invention may be doped with elements such as phosphorus and boron.

As a predetermined substrate, a silicon oxide insulating film layer is formed on a semiconductor substrate such as a semiconductor substrate in which circuit elements and aluminum wiring are formed, and a semiconductor substrate in which circuit elements are formed. A substrate or the like can be used. By polishing the silicon oxide insulating film layer formed on such a semiconductor substrate with the cerium oxide abrasive, unevenness on the surface of the silicon oxide insulating film layer is eliminated, and a smooth surface is formed over the entire semiconductor substrate. I do.

Here, as an apparatus for polishing, a general polishing machine having a holder for holding a semiconductor substrate and a surface plate to which a polishing cloth (pad) is attached (a motor or the like whose rotation speed can be changed) is attached. The device can be used. As the polishing cloth, general nonwoven fabric, foamed polyurethane, porous fluororesin and the like can be used, and there is no particular limitation. Further, it is preferable that the polishing cloth is subjected to a groove processing for storing the slurry.

The polishing conditions are not limited, but the rotation speeds of the holder and the platen are preferably low rotations of 100 min ^-1 or less so that the semiconductor substrate does not pop out. 100kPa so that no
The following is preferred. During polishing, the slurry is continuously supplied to the polishing cloth by a pump or the like. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with the slurry.

It is preferable that the semiconductor substrate after polishing is thoroughly washed in running water, and then water drops adhering to the semiconductor substrate are wiped off using a spin drier or the like, and then dried. A second layer of aluminum wiring is formed on the silicon oxide insulating film layer thus planarized, and a silicon oxide insulating film is formed between the wirings and on the wiring again by the above-described method. By polishing using a cerium abrasive, unevenness on the surface of the insulating film is eliminated, and a smooth surface is formed over the entire surface of the semiconductor substrate. By repeating this process a predetermined number of times, a semiconductor having a desired number of layers is manufactured.

The cerium oxide abrasive of the present invention can be used not only for a silicon oxide insulating film formed on a semiconductor substrate but also for a silicon oxide insulating film formed on a wiring board having predetermined wiring, glass,
Inorganic insulating films such as silicon nitride, optical glasses such as photomasks, lenses, and prisms; inorganic conductive films such as ITO; optical integrated circuits, optical switching elements, optical waveguides, and optical fibers composed of glass and crystalline materials. End face, single crystal for optical such as scintillator, single crystal for solid laser, L for blue laser
It is used for polishing ED sapphire substrates, semiconductor single crystals such as SiC, GaP, and GaAs, glass substrates for magnetic disks, and magnetic heads.

As described above, in the present invention, the predetermined substrate is a semiconductor substrate on which a silicon oxide insulating film is formed, a wiring board on which a silicon oxide insulating film is formed, glass, an inorganic insulating film such as silicon nitride, a photomask or the like. Optical glasses such as lenses and prisms, inorganic conductive films such as ITO, optical integrated circuits, optical switching elements, optical waveguides composed of glass and crystalline materials, optical fiber end faces, optical single crystals such as scintillators , A solid laser single crystal, a blue laser LED sapphire substrate, a semiconductor single crystal such as SiC, GaP, GaAs, a magnetic disk glass substrate, a magnetic head, and the like.

[0033]

Next, the present invention will be described by way of examples.

Example 1 (Preparation of Cerium Oxide Particles) 2 kg of cerium carbonate hydrate was placed in a platinum container and calcined at 800 ° C. for 2 hours in the air to obtain about 1 kg of yellowish white powder. When this powder was subjected to phase identification by an X-ray diffraction method, it was confirmed that the powder was cerium oxide. The particle diameter of the calcined powder was 30 to 100 μm. When the surface of the fired powder particles was observed with a scanning electron microscope, grain boundaries of cerium oxide were observed. When the diameter of primary particles (crystallite) of cerium oxide surrounded by the grain boundaries was measured, the median of the distribution was 190 nm and the maximum was 500 nm.

1 kg of cerium oxide powder was dry-pulverized using a jet mill. Observation of this polycrystal with a scanning electron microscope revealed that in addition to the small particles having the same size as the primary particles (crystallites), a large polycrystal of 1 μm to 3 μm and a polycrystal of 0.5 to 1 μm were obtained. It was mixed. These polycrystals are different from aggregates in which primary particles (crystallites) are re-agglomerated, and two or more primary particles (crystallites)
, And has a crystal grain boundary. Further, the specific surface area of the polycrystal was measured by the BET method and found to be 17 m ² / g.

(Preparation of Cerium Oxide Slurry) The cerium oxide particles 10 prepared in the above-described preparation of cerium oxide particles
23 g of an aqueous solution of polyacrylic acid ammonium salt (40% by weight) having a molecular weight of 10,000 obtained by copolymerizing 00 g with acrylic acid and methyl acrylate at a ratio of 3: 1 and deionized water 8977
g were mixed and ultrasonically dispersed while stirring. Dispersion was performed at an ultrasonic frequency of 40 kHz and a dispersion time of 10 minutes. The resulting slurry was filtered through a 30 micron filter, and 5.0 wt% was added by adding deionized water.
Of cerium oxide slurry was obtained. The pH of the cerium oxide slurry was 8.5. When the particle size distribution of the cerium oxide slurry was examined with a laser diffraction type particle size distribution meter,
The average particle size was 1.29 μm.

The abrasive was stored at 5 ° C. to 40 ° C. for 6 months. Thereafter, the slurry was returned to a cerium oxide slurry having a uniform concentration distribution by stirring, and a laser diffraction particle size distribution measurement was performed. As a result, it was confirmed that the particle size distribution was the same as that immediately after the preparation. Further, by stirring during the polishing, there was no concentration unevenness in the cerium oxide slurry. The concentration of the cerium oxide slurry was determined from the ratio of the weight of the cerium oxide particles to the weight of the slurry. The weight of the cerium oxide particles was determined as the weight of the solid content remaining after the slurry was heated at 150 ° C. to evaporate water.

(Measurement of Weight Ratio of Cerium Oxide and Dispersant Attached to Cerium Oxide) 10 g of the cerium oxide slurry prepared in the preparation of the cerium oxide slurry was heated at 150 ° C.
For 1 hour to evaporate all the water. The solid content is 0.542 g and the amount of dispersant in the slurry is 0.042 g.
It became. Separately, 10 g of the cerium oxide slurry prepared in the preparation of the cerium oxide slurry was separately separated into a cerium oxide and a supernatant by a centrifugal separator.
Heating was performed for a period of time to evaporate all water. The solid content weight was 0.0305 g, and the amount of the dispersant attached to cerium oxide in 10 g of the cerium oxide slurry was determined to be 0.0115 g from the difference between 0.042 g and 0.0305 g.
Since the weight of cerium oxide in 10 g of cerium oxide slurry is 0.5 g, the weight ratio of cerium oxide and the dispersant attached to cerium oxide in the cerium oxide slurry prepared in the preparation of cerium oxide slurry is determined to be 1: 0.0023. Was.

(Polishing of Insulating Film Layer) TEOS-Plasma C
The Si wafer on which the silicon oxide insulating film formed by the VD method was formed was set, and the holder was placed with the insulating film face down on a surface plate on which a polishing pad made of a porous urethane resin was attached. Was set to 30 kPa. A slurry (solid content: 1% by weight) obtained by diluting the above cerium oxide slurry by 5 times with deionized water is put in a container,
It was possible to supply the solution onto the surface plate through a pipe with a pump while stirring. At this time, no sedimentation was observed in both the container and the piping.

While the slurry was dropped on the platen at a rate of 50 cc / min, the platen was rotated at 30 min ^-1 for 2 minutes to polish the insulating film. After polishing, the wafer is removed from the holder, washed well with running water, and then further cleaned with an ultrasonic cleaner.
Washed for minutes. After the cleaning, water droplets were removed from the wafer with a spin dryer, and the wafer was dried with a dryer at 120 ° C. for 10 minutes.
As a result of measuring the change in film thickness before and after polishing using an optical interference type film thickness measuring device, the insulating film of each 400 nm (polishing rate: 400 nm / min) was removed by this polishing, and the uniform thickness was obtained over the entire surface of the wafer. It turned out to be. Also,
When the surface of the insulating film was observed using an optical microscope, no clear scratch was found.

Example 2 (Preparation of Cerium Oxide Particles) 2 kg of cerium carbonate hydrate was put in a platinum container and calcined at 800 ° C. for 2 hours in the air to obtain about 1 kg of yellowish white powder. When this powder was subjected to phase identification by an X-ray diffraction method, it was confirmed that the powder was cerium oxide. The particle diameter of the calcined powder was 30 to 100 μm. When the surface of the fired powder particles was observed with a scanning electron microscope, grain boundaries of cerium oxide were observed. When the diameter of primary particles (crystallite) of cerium oxide surrounded by the grain boundaries was measured, the median of the distribution was 190 nm and the maximum was 500 nm.

1 kg of cerium oxide powder was dry-pulverized using a jet mill. Observation of this polycrystal with a scanning electron microscope revealed that in addition to the small particles having the same size as the primary particles (crystallites), a large polycrystal of 1 μm to 3 μm and a polycrystal of 0.5 to 1 μm were obtained. It was mixed. These polycrystals are different from aggregates in which primary particles (crystallites) are re-agglomerated, and two or more primary particles (crystallites)
, And has a crystal grain boundary. Further, the specific surface area of the polycrystal was measured by the BET method and found to be 17 m ² / g.

(Preparation of Cerium Oxide Slurry) The cerium oxide particles 10 prepared in the above-described preparation of cerium oxide particles
23 g of an aqueous solution of polyacrylic acid ammonium salt (40% by weight) having a molecular weight of 10,000 obtained by copolymerizing 00 g with acrylic acid and methyl acrylate at a ratio of 3: 1 and deionized water 8977
g were mixed and ultrasonically dispersed while stirring. Dispersion was performed at an ultrasonic frequency of 40 kHz and a dispersion time of 10 minutes. The resulting slurry was filtered through a 0.3 micron filter, and further deionized water was added to obtain a 5.0% by weight cerium oxide slurry abrasive. The pH of the cerium oxide slurry was 8.5. When the particle size distribution of the cerium oxide slurry was examined with a laser diffraction type particle size distribution analyzer, the average particle size was 0.16 μm.

The abrasive was stored at 5 ° C. to 40 ° C. for 6 months. Thereafter, the slurry was returned to a cerium oxide slurry having a uniform concentration distribution by stirring, and a laser diffraction particle size distribution measurement was performed. As a result, it was confirmed that the particle size distribution was the same as that immediately after the preparation. Further, by stirring during the polishing, there was no concentration unevenness in the cerium oxide slurry. The concentration of the cerium oxide slurry was determined from the ratio of the weight of the cerium oxide particles to the weight of the slurry. The weight of the cerium oxide particles was determined as the weight of the solid content remaining after the slurry was heated at 150 ° C. to evaporate water.

(Measurement of Weight Ratio of Cerium Oxide and Dispersant Attached to Cerium Oxide) 10 g of the cerium oxide slurry prepared in the preparation of the cerium oxide slurry was heated at 150 ° C.
For 1 hour to evaporate all the water. The solid weight is 0.616 g and the amount of dispersant in the slurry is 0.116 g.
It became. Separately, 10 g of the cerium oxide slurry prepared in the preparation of the cerium oxide slurry was separately separated into a cerium oxide and a supernatant by a centrifugal separator.
Heating was performed for a period of time to evaporate all water. The solid content weight was 0.0915 g, and the amount of the dispersant attached to cerium oxide in 10 g of the cerium oxide slurry was determined to be 0.0245 g from the difference between 0.116 g and 0.0915 g.
Since the weight of cerium oxide in 10 g of cerium oxide slurry is 0.5 g, the weight ratio of cerium oxide to the dispersant attached to cerium oxide in the cerium oxide slurry prepared in the preparation of the cerium oxide slurry is determined to be 1: 0.0049. Was.

(Polishing of Insulating Film Layer) TEOS-Plasma C
The Si wafer on which the silicon oxide insulating film formed by the VD method was formed was set, and the holder was placed with the insulating film face down on a surface plate on which a polishing pad made of a porous urethane resin was attached. Was set to 30 kPa. A slurry (solid content: 1% by weight) obtained by diluting the above cerium oxide slurry by 5 times with deionized water is put in a container,
It was possible to supply the solution onto the surface plate through a pipe with a pump while stirring. At this time, no sedimentation was observed in both the container and the piping.

While the slurry was dropped on the platen at a rate of 50 cc / min, the platen was rotated at 30 min ^-1 for 2 minutes to polish the insulating film. After polishing, the wafer is removed from the holder, washed well with running water, and then further cleaned with an ultrasonic cleaner.
Washed for minutes. After the cleaning, water droplets were removed from the wafer with a spin dryer, and the wafer was dried with a dryer at 120 ° C. for 10 minutes.
As a result of measuring the change in film thickness before and after polishing using an optical interference type film thickness measuring device, the insulating film of 160 nm (polishing rate: 80 nm / min) was respectively removed by this polishing, and the uniform thickness was obtained over the entire surface of the wafer. It turned out to be. When the surface of the insulating film was observed using an optical microscope, no clear damage was found.

[0048]

The cerium oxide abrasive according to any one of claims 1 to 5 has a good dispersibility, can suppress the occurrence of polishing scratches, and can polish a surface to be polished such as a silicon oxide insulating film flat. is there. The method for polishing a substrate according to the sixth and seventh aspects is capable of easily obtaining a high-quality, high-reliability semiconductor substrate with good yield.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 3/14 550 C09K 3/14 550Z

Claims (7)

[Claims] 1. A cerium oxide abrasive comprising a slurry having a weight ratio of cerium oxide to a dispersant attached to cerium oxide in the range of 1: 0.002 to 1: 0.005. 2. The cerium oxide abrasive according to claim 1, wherein the slurry contains a dispersant that is not attached to cerium oxide. 3. The slurry according to claim 1, wherein the slurry contains water as a medium.
Or the cerium oxide abrasive according to 2. 4. The dispersant is at least one compound selected from the group consisting of a water-soluble organic polymer, a water-soluble anionic surfactant, a water-soluble nonionic surfactant and a water-soluble amine. Or the cerium oxide abrasive according to 3. 5. The cerium oxide abrasive according to claim 1, wherein the pH is 7 to 10. 6. A method for polishing a substrate, comprising polishing a predetermined substrate with the cerium oxide abrasive according to claim 1. 7. The method according to claim 6, wherein the predetermined substrate is a semiconductor device having a silicon oxide insulating film formed thereon.