JP2003155471A - Polishing liquid composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polishing liquid composition used for finish-polishing a memory hard disk or polishing a semiconductor element, which gives after polishing a polished matter having a small surface roughness and remarkably reduced in surface defects such as projections, polishing flaws, and particularly in micro-scratches having a depth of at least 0.1 nm and less than 5 nm, a width of at least 10 μm and less than 50 μm and a length of at least 10 μm and less than 1 mm and yet permits economical polishing, to provide a method for decreasing micro-scratches using the polishing liquid composition, and a method for manufacturing a substrate using the polishing liquid composition. SOLUTION: The polishing liquid composition comprises a polishing material having an average primary particle size of 200 nm or less, an antioxidant, an acid having a pK1 of 2 or less and/or a salt thereof, and water, where the acid value (Y) of the polishing liquid composition is 20 mg KOH/g or less and at least 0.2 mg KOH/g. The method for reducing micro-scratches on a substrate comprises using this polishing liquid composition. The method for manufacturing a substrate comprises using this polishing liquid composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polishing composition, a method for reducing micro scratches using the polishing composition, and a method for manufacturing a substrate using the polishing composition.

[0002]

2. Description of the Related Art In recent years, memory hard disk drives are required to have a high capacity and a small diameter, and in order to increase the recording density, it is required to reduce the flying height of a magnetic head or reduce the unit recording area. Along with this, the surface quality required after polishing in the manufacturing process of magnetic disk substrates has become stricter year by year, and in response to low head flying, surface roughness, minute waviness, roll-off, reduction of protrusions and The size and depth of scratches and pits that are permissible corresponding to the decrease in the unit recording area are becoming smaller and smaller.

Also in the semiconductor field, high integration,
The wiring is becoming finer with the increase in speed. In the semiconductor device manufacturing process as well, when the photoresist is exposed, the depth of focus becomes shallower as the wiring becomes finer. Therefore, further smoothing of the pattern formation surface is desired.

In order to meet such requirements, surface roughness Ra, Rm
Polishing liquid compositions having improved surface smoothness of ax, scratches, pits, protrusions, etc. have been proposed (JP-A-9-204657, JP-A-11-167715, JP-A-11-246849). . However, as a result of such improved surface smoothness, minute scratches (depth: 0.1 nm or more and less than 5 nm, width: 10 μm or more, which have not been detected until now,
It has been newly discovered that the length is less than 50 μm and the length is 10 μm or more and less than 1 mm), and it is a problem to reduce the occurrence. Further, conventionally, it is known to further add a polishing step using a slurry of colloidal silica in order to reduce scratches. However, when such a process is performed, the number of processes increases, so that the polishing rate becomes slow and productivity is reduced.

[0005]

DISCLOSURE OF THE INVENTION The object of the present invention is, for finish polishing of a memory hard disk and polishing of semiconductor elements, the surface roughness of an object to be polished after polishing is small and surface defects such as protrusions and polishing scratches. , Especially depth of 0.1nm or more,
Polishing liquid composition capable of significantly reducing fine scratches having a width of less than 5 nm, a width of 10 μm or more and less than 50 μm, and a length of 10 μm or more and less than 1 mm, and capable of polishing economically, and the polishing liquid composition It is an object of the present invention to provide a method for reducing micro scratches using the above method and a method for manufacturing a substrate using the polishing composition.

[0006]

The summary of the present invention is as follows.
[1] Abrasive having an average primary particle size of 200 nm or less, an oxidizing agent, an acid having a pK1 of 2 or less, and / or a salt thereof,
And a water, wherein the polishing composition has an acid value (Y) of 20 mgKOH / g or less, 0.2
A polishing liquid composition having a mgKOH / g or more, [2] A method for reducing micro scratches on a substrate using the polishing liquid composition according to [1], and [3] The polishing liquid composition according to [1] above. The present invention relates to a method of manufacturing a substrate using.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the polishing composition of the present invention comprises an abrasive having an average primary particle diameter of 200 nm or less, an oxidizing agent, an acid having a pK1 of 2 or less, and / or a salt thereof,
And water.

As the abrasive used in the present invention, an abrasive generally used for polishing can be used.
Examples of the abrasive include metal; metal or metalloid carbide, nitride, oxide, boride; diamond and the like.
Metal or metalloid elements are 2A of the periodic table (long period type),
It is derived from 2B, 3A, 3B, 4A, 4B, 5A, 6A, 7A or 8A group. Specific examples of the abrasive include aluminum oxide, silicon carbide, diamond, magnesium oxide, zinc oxide, titanium oxide, cerium oxide, zirconium oxide, silica, and the like, and the use of one or more of these improves the polishing rate. It is preferable from the viewpoint. Among them, aluminum oxide, silica, cerium oxide, zirconium oxide, titanium oxide and the like are suitable for polishing precision wafers such as semiconductor wafers, semiconductor elements and magnetic recording medium substrates. For aluminum oxide, α, θ, γ
Various crystal systems are known, and they can be appropriately selected and used according to the application. Among them, silica, particularly colloidal silica, is suitable for final finishing polishing of substrates for high recording density memory magnetic disks and polishing for semiconductor device substrates which require higher smoothness.

The average particle diameter of the primary particles of the abrasive is 200n.
m or less, and from the viewpoint of improving the polishing rate, preferably 1 nm or more, more preferably 10 nm or more, further preferably 20 nm or more, and the surface roughness (Ra, Rm
200n from the viewpoint of reducing ax) and waviness (Wa)
m or less, preferably 150 nm or less, more preferably 1
It is 20 nm or less, and particularly preferably 100 nm or less.
The average particle size of the primary particles is preferably 1 to 200 nm,
More preferably from 1 to 150 nm, even more preferably 10
-120 nm, especially preferably 20-100 nm. Furthermore, when the primary particles are aggregated to form secondary particles, the average particle diameter of the secondary particles is the same from the viewpoint of improving the polishing rate and reducing the surface roughness of the object to be polished. , Preferably 50 to 3000 nm, more preferably 100 to 1500 nm, and particularly preferably 200 to
It is 1200 nm. The average particle size of the primary particles of the abrasive is
Analyze the image observed with a scanning electron microscope (preferably 3000 to 100,000 times) and measure the particle size (D50) at which the cumulative particle size distribution (number basis) from the small particle size side of the primary particles is 50% It can be obtained by doing. Here, as the particle size of one primary particle, a biaxial average (average of major axis and minor axis) particle diameter is used. The average particle diameter of the secondary particles can be measured as a volume average particle diameter by using a laser light diffraction method.

In the present invention, the surface roughness (Ra,
From the viewpoint of reducing Rmax), waviness (Wa), surface defects such as scratches, and improving the surface quality, it is more preferable to use silica particles as the abrasive. Examples of the silica particles include colloidal silica particles, fumed silica particles, surface-modified silica particles, and the like. Among them, colloidal silica particles are preferable. The colloidal silica particles can be obtained, for example, by a production method in which an aqueous solution of silicic acid is used.

In the present invention, by using the polishing composition containing the silica particles having the above-mentioned particle size distribution, the surface roughness of the substrate to be polished after polishing is small, and the projections, polishing scratches, etc. The effect that the substrate to be polished can be polished at an economical rate without the occurrence of surface defects is exhibited.

The particle size of silica particles in the above particle size distribution can be determined by the following method using a scanning electron microscope (hereinafter referred to as SEM). That is, the polishing liquid composition containing silica particles had a silica particle concentration of 0.5% by weight.
Dilute with ethanol to make The diluted solution is uniformly applied to a sample stage for SEM heated to about 50 ° C. Then, the excess solution is sucked with a filter paper and air-dried uniformly so that the solution does not aggregate.

Pt-Pd was vapor-deposited on naturally dried silica particles, and about 500 particles were observed in the visual field by using a field effect scanning electron microscope (FE-SEM: S-4000 type) manufactured by Hitachi, Ltd. The magnification is adjusted to 3000 times to 100,000 times so that the silica particles of (1) are observed, and two points are observed on one sample stage to take a photograph. Photo taken (10.16)
cm x 12.7 cm) with A4 size (210
(mm × 297 mm), and measure the particle size of all the imaged silica particles with calipers and add up. This operation is repeated several times so that the number of measured silica particles is 2000 or more. Increasing the number of measurement points by SEM is more preferable from the viewpoint of obtaining an accurate particle size distribution.
The measured particle diameters are totaled, and the frequency (%) is added in order from the smallest particle diameter, and the particle diameter distribution based on the number in the present invention can be obtained by setting the particle diameter at which the value becomes 50% as D50. The particle size distribution mentioned here is obtained as the particle size distribution of primary particles. For abrasives other than silica particles, when the abrasive is in the form of a slurry dispersed in a solvent such as water or alcohol, the particle size distribution can be determined by the same method as the above silica particles. Specific examples thereof include aluminum oxide, titanium oxide, zirconium oxide, zinc oxide and the like produced by a growth (build-up) method. On the other hand, when the abrasive is in powder form, a conductive tape is attached to the SEM sample stand, the abrasive powder is directly sprinkled on the tape, and then Pt-Pd is vapor-deposited to prepare a sample. The particle size distribution can be obtained in the same manner as in the case of particles. Specific examples thereof include silicon carbide, diamond, aluminum oxide, and cerium oxide produced by a pulverization method. Further, when there are particles in which primary particles such as aluminum oxide, cerium oxide, and fumed silica are fused, the fused particles can be regarded as primary particles, and the particle size distribution can be obtained.

The method for adjusting the particle size distribution of the silica particles is not particularly limited. For example, when the silica particles are colloidal silica, particles that become new nuclei in the growth process of the particles in the manufacturing stage are added. Therefore, it can be achieved by a method of giving the final product a particle size distribution, a method of mixing two or more silica particles having different particle size distributions, or the like.

The content of the abrasive in the abrasive composition is preferably 0.5% by weight or more, more preferably 1% by weight or more, further preferably 3% by weight or more, particularly preferably from the viewpoint of improving the polishing rate. 5% by weight or more, and from the viewpoint of improving the surface quality and economical efficiency, preferably 20% by weight or less, more preferably 15% by weight or less, further preferably 13% by weight or less, particularly preferably 10% by weight or less. It is less than or equal to weight%.

That is, the content is preferably 0.5 to
It is 20% by weight, more preferably 1 to 15% by weight, further preferably 3 to 13% by weight, particularly preferably 5 to 10% by weight.

The oxidizing agent used in the present invention includes peroxide, permanganic acid or a salt thereof, chromic acid or a salt thereof,
Examples thereof include nitric acid or a salt thereof, peroxo acid or a salt thereof, oxygen acid or a salt thereof, metal salts, sulfuric acid and the like. In the present invention, the use of such an oxidizing agent has an advantage that the polishing rate can be improved.

The above-mentioned peroxides include hydrogen peroxide, sodium peroxide, barium peroxide, etc .; permanganate or its salts, such as potassium permanganate; chromic acid or its salts, metal chromates. , Dichromic acid metal salt, etc .; nitric acid or its salt, nitric acid, iron (III) nitrate, ammonium nitrate, etc .; peroxo acid or its salt,
Peroxodisulfate, ammonium peroxodisulfate, peroxodisulfate metal salt, peroxophosphoric acid, peroxosulfate, sodium peroxoborate, performic acid, peracetic acid,
Perbenzoic acid, perphthalic acid, etc .; Oxygen acids or salts thereof include hypochlorous acid, hypobromic acid, hypoiodic acid, chloric acid,
Bromic acid, iodic acid, sodium hypochlorite, calcium hypochlorite, etc .; as metal salts, iron (III) chloride, iron (III) sulfate, iron (III) citrate, iron iron sulfate (II)
I) and the like. Preferred oxidizing agents include hydrogen peroxide, iron (III) nitrate, peracetic acid, ammonium peroxodisulfate, iron (III) sulfate and ammonium iron (III) sulfate. In particular, hydrogen peroxide is preferable from the viewpoint that metal ions do not adhere to the surface and it is used widely and is inexpensive. You may use these oxidizing agents individually or in mixture of 2 or more types. Among these oxidizing agents, nitric acid or a salt thereof can also be used as an acid having a pK1 of 2 or less described later or a salt thereof.

From the viewpoint of improving the polishing rate, the content of the oxidizing agent in the polishing composition is preferably 0.002% by weight or more, more preferably 0.005% by weight or more, further preferably 0.007% by weight or more, particularly preferably It is 0.01% by weight or more, preferably 20% by weight or less, more preferably from the viewpoint of improving surface quality by reducing surface roughness and waviness, reducing surface defects such as pits and scratches, and economical efficiency. It is 15% by weight or less, more preferably 10% by weight or less, and particularly preferably 5% by weight or less. The content is
Preferably 0.002 to 20% by weight, more preferably 0.005 to
15% by weight, more preferably 0.007 to 10% by weight, particularly preferably 0.01 to 5% by weight.

The acid and / or salt thereof used in the present invention is preferably a compound having a pK1 of 2 or less,
From the viewpoint of reducing micro scratches, a compound having a pK1 of 1.5 or less, more preferably 1 or less, and most preferably a strong acidity that cannot be represented by pK1 is desirable. Examples thereof include nitric acid, sulfuric acid, sulfurous acid, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, phosphonic acid, phosphinic acid, pyrophosphoric acid,
Inorganic acids such as tripolyphosphoric acid and amidosulfuric acid and salts thereof, 2
-Aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), ethane-1,1, -diphosphonic acid , Ethane-1,
1,2-triphosphonic acid, ethane-1-hydroxy-
1,1-diphosphonic acid, ethane-1-hydroxy-1,
1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-
Organic phosphonic acids such as phosphonobutane-2,3,4-tricarboxylic acid and α-methylphosphonosuccinic acid and salts thereof,
Examples thereof include aminocarboxylic acids such as glutamic acid, picolinic acid, and aspartic acid, and salts thereof, carboxylic acids such as oxalic acid, nitroacetic acid, maleic acid, oxaloacetic acid, and salts thereof, and the like. Above all, from the viewpoint of reducing minute scratches,
Inorganic acids, organic phosphonic acids and salts thereof are preferred. Also,
Among the inorganic acids and salts thereof, nitric acid, sulfuric acid, hydrochloric acid, perchloric acid and salts thereof are more preferable. Among organic phosphonic acids and their salts, 1-hydroxyethylidene-1,1-
Diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and salts thereof are more preferable. These acids and salts thereof may be used alone or in combination of two or more. Where pK1
Is the acid dissociation constant (25
The logarithm of the reciprocal of (° C.) is usually expressed as PKa, and the logarithm of the reciprocal of the primary acid dissociation constant is defined as pK1. The pK1 of each compound is, for example, the revised 4th edition Chemical Manual (Basic) II,
pp316-325 (edited by the Chemical Society of Japan) and the like. In the present invention, it is particularly preferable to use an acid having a pK1 of 2 or less and / or a salt thereof, from the viewpoint of achieving both a fine scratch reduction and a polishing rate.

The salts of these acids are not particularly limited, and specific examples thereof include salts with metals, ammonium, alkylammonium, organic amines and the like. Specific examples of the metal include periodic table (long period type) 1A, 1B, 2A,
Examples thereof include metals belonging to 2B, 3A, 3B, 4A, 6A, 7A or 8 groups. Among these, a salt with a metal belonging to Group 1A or ammonium is preferable from the viewpoint of reducing minute scratches.

The content of an acid having a pK1 of 2 or less and a salt thereof in the polishing composition is preferably 0.0001 to 5% by weight, more preferably from the viewpoint of exhibiting a sufficient polishing rate and improving the surface quality. Is 0.0003 to 3% by weight, more preferably 0.001 to 2% by weight, and particularly preferably 0.0025 to 1% by weight.

The water in the polishing composition of the present invention is used as a medium, and the content thereof is preferably 55% by weight or more from the viewpoint of efficiently polishing an object to be polished, It is preferably 67% by weight or more, more preferably 75% by weight or more, particularly preferably 84% by weight or more, preferably 99.4979% by weight or less, more preferably 98.9947% by weight or less, further preferably 96.992.
It is preferably not more than 9% by weight, particularly preferably not more than 94.9875% by weight. The content is preferably 55 to 99.4979% by weight, more preferably 67 to 98.9947% by weight, further preferably 75 to 99.4979% by weight.
96.992% by weight, particularly preferably 84-94.9875% by weight.

The concentration of each component in the polishing composition may be either the concentration at the time of producing the composition or the concentration at the time of use. Usually, a polishing composition is produced as a concentrated solution, and it is often used by diluting it.

Further, the polishing composition of the present invention may contain other components, if necessary. Examples of the other components include thickeners, dispersants, rust preventives, basic substances, surfactants and the like.

The polishing composition of the present invention comprises an abrasive having an average primary particle size of 200 nm or less, an oxidizer, an acid having a pK1 of 2 or less, and / or a salt thereof, water, and other components as necessary. And the like can be prepared by mixing them by a known method.

The acid value (Y) of the polishing composition of the present invention is 2
It is 0 mgKOH / g or less and 0.2 mgKOH / g or more. Especially, when the polishing liquid composition contains an organic phosphonic acid as an acid having a pK1 of 2 or less, the acid value (Y) is 15 mg from the viewpoint of reducing fine scratches.
KOH / g or less is preferable, 10 mgKOH / g or less is more preferable, 7 mgKOH / g or less is particularly preferable,
Most preferred is 3 mg KOH / g or less. When an inorganic acid is contained as an acid having a pK1 of 2 or less, it is preferably 5 mgKOH / g or less, more preferably 3 mgKOH / g or less, and 1.8 mg from the viewpoint of reducing minute scratches.
KOH / g or less is particularly preferable, 1.5 mg KOH / g
The following are the most preferable.

From the viewpoint of improving the polishing rate, the acid value (Y) is preferably 0.2 mgKOH / g or more, more preferably 0.25 mgKOH / g or more, and 0.1.
3 mgKOH / g or more is more preferable, 0.35 mgK
OH / g or more is more preferable, 0.4 mgKOH / g or more is more preferable, 0.45 mgKOH / g or more is more preferable, 0.5 mgKOH / g or more is further preferable,
0.75 mg KOH / g or more is particularly preferable, 1.0 m
Most preferably gKOH / g or more.

The acid value (Y) is measured according to JIS K 1557, and is determined as the amount of potassium hydroxide (mg) required for neutralization per 1 g of the polishing liquid composition.

The acid value (Y) of the polishing composition of the present invention
From the viewpoint of reducing minute scratches, the formula (1): Y (mgKOH / g) ≤ 5.7 × 10 ^-17 × X (pieces / g) + 19.45 (1) (where X is a polishing liquid It represents the number concentration of the abrasive in the composition).

As described above, minute scratches are surface defects that have not been noticed until now, and nothing has been clarified about the mechanism of their occurrence. Therefore, as a result of diligent studies by the present inventors, surprisingly, the occurrence of micro scratches is the degree of corrosiveness of the polishing composition and the degree of direct contact between the polishing pad and the object to be polished during polishing. Newly discovered that it depends on the balance of.
Specifically, the relationship of the above formula (1) is shown, in which the degree of corrosiveness of the polishing composition is represented by an acid value, and the degree of direct contact between the polishing pad and the object to be polished is represented by the number concentration of the abrasive. It has been discovered that micro scratches can be significantly reduced by using a polishing composition.

In the present invention, when the acid value (Y) of the polishing composition and the number concentration of the polishing agent satisfy the relationship of the formula (1), a mechanical factor (direct contact between the pad and the polishing object) with respect to the polishing object. And the chemical factor (corrosiveness) are balanced, the effect of significantly reducing micro scratches is exhibited. Here, the equation (1) shows the relationship between the number concentration (X) of the abrasive which is the mechanical factor and the acid value (Y) which is the chemical factor, and the acid value (Y) is the concentration of the abrasive on the right side. Being less than or equal to the value derived from the linear function of the above, corrosiveness that can significantly reduce micro scratches when the condition of direct contact between the pad and the object to be polished is determined at the number concentration (X) of a specific abrasive. Means that the upper limit of the strength (acid value (Y)) is determined. In particular, by polishing the substrate with a polishing composition that satisfies the relationship of the above formula (1), the minute scratches are “large” or “medium” according to the depth degree thereof, as in Examples described later. , And “small”, the effect of reducing three types of minute scratches from the substrate to the extent that there is no practical effect is exhibited.

The number concentration (number / g): X of the abrasive in the polishing composition is calculated by the following equation (2).

[0034]

[Equation 1]

The true specific gravity of the polishing material is, for example, "The Chemistry Of Silica" in the case of silica.
(Iler, Ralph K., 1979 John Wiley & Sons, In
From c.) 2.2 g / cm ³ of amorphous silica can be used. If there is no literature value, it can be determined from the experimental value of the average particle size of the primary particles and the specific surface area by the BET method, and the average particle size of the primary particles used at that time can be observed with a scanning electron microscope as described above. (Preferably 3000 to 100,000
The doubled image is analyzed, and the integrated particle size distribution (number basis) from the small particle size side of the primary particles is 50% (D50)
Can be used.

As a method of adjusting Y so as to satisfy the formula (1), for example, the upper limit of the acid value (Y), which is previously calculated from the number concentration of the abrasive, is divided by the weight 56110 mg of 1 mol of KOH, and It is converted to [mol / g], the obtained converted value is multiplied by the molecular weight of the acid [nitric acid, etc.] to be used, and the value is converted to [% by weight], and the obtained value is used as the upper limit of the acid addition amount. Examples thereof include a method of preparing a polishing composition.

When the polishing composition contains an inorganic acid and / or its salt, Y (mgKOH / g) ≦ 5.7 × 10 ⁻¹⁷ × X (pieces / piece) from the viewpoint of reducing minute scratches.
g) +3.00 is preferred, and Y (mgKOH / g
) ≦ 5.7 × 10 ⁻¹⁷ × X (pieces / g) +1.77 is more preferable, and Y (mgKOH / g) ≦ 5.7 × 1
It is particularly preferable that 0 ⁻¹⁷ × X (pieces / g) +1.67 is satisfied, and Y (mgKOH / g) ≦ 5.7 × 10 ⁻¹⁷ × X (pieces
/g)+1.47 is most preferable.

When the polishing composition contains an acid having a pK1 of 2 or less other than an inorganic acid and / or a salt thereof, particularly an organic phosphonic acid and / or a salt thereof, Y (mgKOH / g) ≤ 5.7 x 10 ^-17 x X
(Pieces / g) +14.45 is more preferable, and Y
(MgKOH / g) ≦ 5.7 × 10 ⁻¹⁷ × X (pieces / g) +9.
45 is more preferable, and Y (mgKOH / g) ≦ 5.
It is particularly preferable that 7 × 10 ⁻¹⁷ × X (pieces / g) +6.45 is satisfied, and Y (mgKOH / g) ≦ 5.7 × 10 ⁻¹⁷ ×
Most preferably, X (pieces / g) +2.45 is satisfied.

The pH of the polishing composition of the present invention is preferably determined as appropriate according to the type of work piece and required performance. Although it cannot be unequivocally limited depending on the material to be polished, generally, in the case of a metal material, the pH is preferably acidic, preferably less than 7.0, and more preferably from the viewpoint of improving the polishing rate.
6.0 or less, more preferably 5.0 or less, particularly preferably
It is preferably 4.0 or less. Further, from the viewpoint of the effect on the human body and the corrosiveness of the machine, the pH is preferably 1.0 or more, more preferably 1.2 or more, and further preferably
It is 1.4 or more, particularly preferably 1.6 or more. Particularly in the case of precision component substrates mainly intended for metals such as nickel-phosphorus (Ni-P) plated aluminum alloy substrates, the pH is preferably acidified from the viewpoint of polishing rate,
From the viewpoint of improving the polishing rate, the pH is preferably 4.5 or less, more preferably 4.0 or less, further preferably 3.5 or less, and particularly preferably 3.0 or less. Therefore, it suffices to set the pH according to the purpose of importance, but especially Ni-P
For precision component substrates targeting metals such as plated aluminum alloy substrates, the
Is preferably 1.0 to 4.5, more preferably 1.2 to 4.0,
More preferably 1.4 to 3.5, and particularly preferably 1.6 to 3.0.
Is. The pH may be selected from inorganic acids such as nitric acid and sulfuric acid, organic acids such as oxalic acid, ammonium salts, aqueous ammonia, potassium hydroxide, sodium hydroxide, and basic substances such as amines.
It can be adjusted by blending in a desired amount.

As a method of reducing the minute scratches of the present invention, there is a method of using the polishing composition of the present invention when polishing a substrate to be polished. As a method for polishing a substrate to be polished, the polishing liquid composition of the present invention is used, or each component is mixed so as to have the composition of the polishing liquid composition of the present invention to prepare a polishing liquid composition to be polished. The method has a step of polishing the substrate, and in particular, the substrate for precision parts can be suitably manufactured. Further, the polishing composition of the present invention has surface defects,
In particular, the generation of minute scratches can be significantly reduced and a high polishing rate can be exhibited.

Materials to be polished which are intended for the polishing composition of the present invention include, for example, metals such as silicon, aluminum, nickel, tungsten, copper, tantalum and titanium, metalloids and alloys thereof, and glass. Examples thereof include glassy substances such as glassy carbon and amorphous carbon, ceramic materials such as alumina, silicon dioxide, silicon nitride, tantalum nitride and titanium carbide, and resins such as polyimide resin. Among these, metals such as aluminum, nickel, tungsten, and copper, and alloys containing these metals as the main components are the objects to be polished, or such as semiconductor substrates such as semiconductor elements, they contain metal. It is preferably an object to be polished, for example, a Ni-P plated aluminum alloy substrate or a glass substrate such as crystallized glass or tempered glass is more preferable, and a Ni-P plated aluminum alloy substrate is particularly preferable.

The shape of the object to be polished is not particularly limited, and for example, a shape having a flat surface portion such as a disk shape, a plate shape, a slab shape, a prism shape, or a shape having a curved surface portion such as a lens is used for the polishing of the present invention. It becomes the object of polishing using the liquid composition.
Among them, it is particularly excellent in polishing a disk-shaped object to be polished.

The polishing composition of the present invention is suitable for polishing precision component substrates. For example, it is suitable for polishing substrates for magnetic recording media such as magnetic disks, optical disks, magneto-optical disks, photomask substrates, optical lenses, optical mirrors, optical prisms, precision component substrates such as semiconductor substrates.
The polishing of a semiconductor substrate includes a silicon wafer (bare wafer) polishing step, a buried element isolation film forming step, an interlayer insulating film flattening step, a buried metal wiring forming step,
This is performed in the embedded capacitor forming process and the like. The polishing composition of the present invention is particularly suitable for polishing a magnetic disk substrate. Further, it is suitable for obtaining a magnetic disk substrate having a surface roughness (Ra) of 0.3 nm or less and a waviness (Wa) of 0.3 nm or less.

In the present specification, the surface roughness (Ra) and the waviness (Wa) are obtained as generally called center line roughness, and the center line average roughness obtained from a roughness curve having a wavelength component of 80 μm or less. Is referred to as Ra, and the centerline average roughness of the roughness curve having a wavelength component of 0.4 to 5 mm is represented as Wa as the centerline average minute waviness. These can be measured as follows.

Centerline average roughness: Measured under the following conditions using Tally Step (Taridata 2000) manufactured by Ra Rank Taylor Hobson. Stylus tip size: 2.5 μm × 2.5 μm High-pass filter: 80 μm Measurement length: 0.64 mm

Center line average minute waviness: Measured under the following conditions using New View 200 manufactured by Wa Zygo. Objective lens: 2.5 times ImageZoom: 0.5 times Filter: Band Pass Filter type: FFT Fixed Filter High Wavelength: 0.4 mm Filter Low Wavelength: 5.0 mm Remover: Cylinder

As a polishing method using the polishing composition of the present invention, for example, the substrate is sandwiched by a polishing plate having a non-woven organic polymer polishing cloth attached thereto, and the polishing composition is supplied to the polishing surface. Examples include a method of polishing by moving a polishing disk or a substrate while applying a constant pressure. In the method, by using the polishing composition of the present invention, the generation of minute scratches is significantly suppressed, and the polishing rate is improved, the generation of surface defects such as scratches and pits is suppressed, and the surface roughness ( Surface smoothness such as Ra) and waviness (Wa) can be improved. That is, the polishing method is a method for reducing minute scratches on the substrate.

The method for producing a substrate of the present invention has a polishing step using the polishing composition, and the polishing step is preferably performed after the second step among a plurality of polishing steps.
It is particularly preferable to perform the final polishing step. For example, 1
Surface roughness (Ra) by one step or two-step polishing step
A Ni-P-plated aluminum alloy substrate having a undulation (Wa) of 0.5 to 1.5 nm and a waviness (Wa) of 0.5 to 1 nm is polished by a polishing step using the polishing composition of the present invention to obtain surface roughness. (Ra) 0.3 nm or less, waviness (Wa)
A magnetic disk substrate having a thickness of 0.3 nm or less is preferably used with a surface roughness (Ra) of 0.25 nm or less and a waviness (Wa) of 0.
A magnetic disk substrate of 25 nm or less can be manufactured. In particular, the polishing composition of the present invention has a surface roughness (Ra) of 0.3 nm or less and a waviness (Wa) of 0.
A magnetic disk substrate having a thickness of 3 nm or less is preferably used with a surface roughness (Ra) of 0.25 nm or less and a waviness (Wa) of 0.25.
It is suitable for use in the second step when manufacturing a magnetic disk substrate having a thickness of nm or less.

The manufactured substrate is excellent in surface smoothness in addition to the remarkable reduction of minute scratches. As the surface smoothness, a surface roughness (Ra) of 0.
3 nm or less, preferably 0.25 nm or less is desirable.
The waviness (Wa) is 0.3 nm or less, preferably 0.25 nm or less.

As described above, the use of the polishing composition of the present invention remarkably reduces the generation of minute scratches,
While improving the polishing rate, surface defects such as scratches and pits are small, and surface roughness (Ra) and waviness (W)
It is possible to manufacture a high-quality substrate having excellent surface properties such as a) having improved smoothness with high production efficiency.

The polishing composition of the present invention is particularly effective in the polishing step, but can be similarly applied to other polishing steps such as lapping.

[0052]

Example (Substance to be Polished) As a substrate to be polished, a substrate plated with Ni-P was rough-polished in advance with a polishing liquid containing an alumina polishing material to have a substrate surface roughness (Ra) of 1 nm and a thickness of 0.8. Polishing evaluation was performed using an aluminum alloy substrate having a diameter of 95 mm and a diameter of 95 mm.

Examples 1 to 18 As shown in Table 1, commercially available colloidal silica (A (average particle size 50 nm): manufactured by Nippon Kagaku Kogyo, B (average particle size 80 nm): manufactured by Stark Vuitc Co., Ltd., C ( Average particle size 20 nm): DuPont Co., Ltd.), 35 wt% hydrogen peroxide (Asahi Denka Co., Ltd.), 60 wt% nitric acid (Wako Pure Chemical Industries, Ltd., pK1 is 0 or less),
Each component such as 98% by weight sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd., pK1 is 0 or less) and the rest were water so that the total amount was 100% by weight. The order of mixing was such that first, hydrogen peroxide was mixed with an aqueous solution of nitric acid or sulfuric acid diluted with water, then the remaining components were mixed, and finally the colloidal silica slurry was rapidly added while stirring so as not to gel. In the table, HEDP is 1-hydroxyethylidene-1,1-diphosphonic acid (manufactured by Solusia Japan),
ATMP means aminotri (methylenephosphonic acid) (manufactured by Solusia Japan).

[0054]

[Table 1]

Comparative Examples 1 to 7 As shown in Table 2, commercially available colloidal silica (A (average particle size 50 nm): manufactured by Nippon Kagaku Kogyo, B (average particle size 80 nm): manufactured by Stark Vuitc Co., Ltd., C) (Average particle size 20 nm): DuPont Co., Ltd., 35 wt% hydrogen peroxide (Asahi Denka Kogyo), 60 wt% nitric acid (Wako Pure Chemical Industries, Ltd.), aluminum nitrate nonahydrate ( Special grade: Wako Pure Chemical Industries, Ltd.
And a predetermined amount of the other components and the rest as water, so that the total amount was 100% by weight. The order of mixing is as follows. First, hydrogen peroxide and aluminum nitrate nonahydrate are mixed with an aqueous solution of nitric acid diluted with water, then the remaining components are mixed, and finally while stirring the colloidal silica slurry so as not to gel. It was quickly added and prepared. In the table, ammonium persulfate and succinic acid are those produced by Wako Pure Chemical Industries, Ltd., and special grades are used, and Al nitrate is aluminum nitrate nonahydrate (produced by Wako Pure Chemical Industries, Ltd., special grade).

[0056]

[Table 2]

With respect to the polishing liquid compositions obtained in Examples 1 to 18 and Comparative Examples 1 to 7, the acid value, the number concentration of the abrasive, the polishing rate and the minute scratches, surface roughness, minute waviness,
The presence or absence of surface defects and scratches was measured and evaluated based on the following method. The obtained results are shown in Tables 1 to 4.

(Polishing condition) Polishing tester: Double-sided 9B polisher manufactured by Speed Fam Polishing pad: Belltrix N0058 Plate rotation speed: 35r / min Slurry supply rate: 40 ml / min Polishing time: 4 minutes Polishing load: 7.8 kPa Number of substrates loaded: 10

(Measurement of Acid Value) About 50 g of the polishing composition was weighed in a 100-ml collection vial (BP221S Sartorius).
(Manufactured by Mfg. Co., Ltd.) was used to record up to 4 digits after the decimal point.
Next, while stirring with a Teflon (registered trademark) stirrer, a 3-point calibration (pH = 4.01 (25 ° C .: phthalate pH standard solution (Toa Denpa Kogyo)), pH = 6.86 (25 ° C .: medium) Phosphate (manufactured by Toa Denpa Kogyo), pH = 9.18 (25 ° C: borate p
H standard solution (Katayama Chemical Co., Ltd.)) pH meter (HM-3
The pH was measured with 0G (manufactured by Toa Denpa Kogyo KK), electrode: GST-5721C. Using a 10 ml titration tube, 0.1 mol / L potassium hydroxide aqueous solution (factor 1.000; manufactured by Sigma-Aldrich Japan) was added dropwise, and the amount (ml) showing pH 7.00 was obtained (usually 4 points around pH 7.00). Calculated by interpolation from the data). Amount of polishing liquid (g) and required amount of potassium hydroxide (ml)
The amount of potassium hydroxide required to neutralize the polishing composition per 1 g was calculated from, and this was calculated as the acid value (measured value) (mg
KOH / g). In the table, the acid value (calculated value) means a value obtained by substituting the number concentration of the abrasive obtained as described later into the linear function of the right side of the above formula (1).

(Calculation of Number Concentration of Abrasive Material) In the above formula (2), specific gravity was calculated as 2.2 g / cm ³ of amorphous silica.

(Polishing speed) Difference in substrate weight before and after polishing test
The amount of double-sided polishing per unit time is calculated by dividing (g) by the specific gravity (8.4 g / cm ³ ) and then by the disk surface area (65.97 cm ² ) and the polishing time.

(Small scratch) Differential interference microscope system (metallurgical microscope: BX60M (manufactured by Olympus Optical Co., Ltd.),
Objective lens: UMPlan FI 5 × / 0.15 BD P, CCD Color camera: ICD-500AC (manufactured by Ikegami Tsushinki), Color monitor: UCM-1000 REV.8 (manufactured by Ikegami Tsushinki)) to cover the entire surface of 10 substrates to be polished. Observed, micro scratches (depth 0.1 nm or more, less than 5 nm, width 10 μm or more,
The number of sheets having a length of less than 50 μm and a length of 10 μm or more and less than 1 mm) was counted by visually categorizing the degree of occurrence of micro scratches into large / medium / small. The evaluation criteria for large, medium and small are as follows. "Large": (depth) 1.0 nm or more and less than 5.0 nm,
(Width) 10 μm or more and less than 50 μm, (Length) 10 μm or more and less than 1 mm, “Medium”: (depth) 0.5 nm or more and less than 1.0 nm,
(Width) 10 μm or more and less than 50 μm, (length) 10 μm or more and less than 1 mm, “small”: (depth) 0.1 nm or more and less than 0.5 nm,
(Width) 10 μm or more and less than 50 μm, (Length) 10 μm or more and less than 1 mm In the present invention, “large” is 0 sheets and “medium” is 5 sheets or less out of 10 sheets, and it is regarded as a passing product.

(Surface Roughness (Ra, Rmax)) Atomic force microscope (Nanoscope III manufactured by Digital Instruments Co., Ltd.) was used, and a total of 6 points were set at 3 points for each 120 ° on the front and back of the substrate to be polished.
, Dimension3000) and scan rate 2 at 1.0Hz.
The average value was taken when measuring the range of μm × 2 μm.
(Ra) ○: less than 0.35 nm, ×: 0.35 nm or more, (Rma
x) ⊚: less than 3 nm, ◯: 3 nm or more and less than 5 nm, Δ: 5 nm or more and less than 10 nm, x: 10 nm or more are shown in Tables 3 and 4. In addition, "Ra" is the center line average roughness, and "Rmax" is PV.
The value (Peak-to-Valley value) is shown.

(Micro waviness (Wa)) The measurement was carried out by an optical surface profile measuring device (NewView200: manufactured by Zygo) under the above conditions. ◯: less than 0.45 nm, x: 0.45 nm or more are shown in Tables 3 and 4.

(Surface defect) Differential interference microscope observation (metallurgical microscope BX60M (manufactured by Olympus Corporation) Eyepiece x 1
The number of pits and protrusions per 12 fields of view was counted by measuring the surface of each substrate at 30 positions every 30 ° by using 0, the objective lens × 20). ◯: 0, x: 1 or more are shown in Tables 3 and 4.

(Scratch) High intensity lamp (HPS-250:
The surface of 10 substrates was visually observed by observation and the number of scratches per substrate was counted. It was not possible to observe the minute scratches with this high-intensity lamp. ○: (depth 5 nm or more, length 1
Scratches of mm or more) 5 or less, x: 6 or more are shown in Tables 3 and 4.

[0067]

[Table 3]

[0068]

[Table 4]

From the results shown in Tables 3 and 4, the polishing liquid compositions obtained in Examples 1 to 18 are all more effective in reducing micro scratches than the polishing liquid compositions obtained in Comparative Examples 1 to 7. It turns out that it is remarkably excellent. In addition, Examples 1 to 1
It can be seen that the polishing liquid compositions obtained in 18 all have a high polishing rate and are excellent in surface quality such as surface roughness, minute waviness, surface defects and scratches.

[0070]

EFFECTS OF THE INVENTION By using the polishing composition of the present invention, the surface roughness is small and the surface defects such as protrusions and polishing scratches, particularly the depth is 0.1 nm or more and less than 5 nm and the width is 10 nm.
μm or more, less than 50 μm, length 10 μm or more, 1 mm
It is possible to economically manufacture a substrate for a memory hard disk, a semiconductor element, or the like in which the minute scratches below are significantly reduced.

Continued front page    F term (reference) 3C058 AA07 AC04 CB01 DA17                 5D112 AA02 AA03 BA06 BA09 BD06                       GA09

Claims (9)

[Claims] 1. A polishing composition comprising an abrasive having an average primary particle size of 200 nm or less, an oxidizing agent, an acid and / or salt thereof having a pK1 of 2 or less, and water, The acid value (Y) of the polishing composition is 20 mgKOH / g or less,
A polishing composition containing 0.2 mgKOH / g or more. 2. The polishing composition according to claim 1, wherein the acid having a pK1 of 2 or less and / or a salt thereof is an organic phosphonic acid and / or a salt thereof. 3. The acid value (Y) of the polishing composition is 15 mgK.
The polishing composition according to claim 2, which has an OH / g ratio of 0.2 mgKOH / g or more. 4. The polishing composition according to claim 1, wherein the acid having a pK1 of 2 or less and / or its salt is an inorganic acid and / or its salt. 5. The acid value (Y) of the polishing composition is 5 mgKO.
H / g or less, 0.2 mgKOH / g or more.
The polishing composition described. 6. The polishing composition according to claim 1, wherein the polishing composition has an acid value (Y) represented by the formula (1): Y (mgKOH / g) ≦ 5.7 ×. 10 ^-17 × X (pieces / g) + 19.45 (1) (where X represents the number concentration of the abrasive in the polishing composition), and the polishing composition. 7. The polishing liquid composition according to claim 1, which is used for polishing a magnetic disk substrate. 8. A method for reducing minute scratches on a substrate using the polishing composition according to claim 1. 9. A method for producing a substrate using the polishing composition according to claim 1.