JP4251516B2 - Polishing liquid composition - Google Patents

Description

【００４２】
本発明の粒径分布を有する研磨液組成物を得るために、表２に示す割合で、研磨材濃度が２５重量％となるように配合し、さらに研磨促進剤としてＥＤＴＡ−Ｆe 塩（キレスト（株）製、商品名：キレストＦｅ）３重量％、及び残部イオン交換水をそれぞれ添加混合して、研磨液組成物を調製した。
【００４３】
【表２】

【００４４】
被研磨基板として、Ｎｉ−Ｐメッキされた表面粗さＲａ＝１５Å、厚さ：０．８ｍｍの直径３．５インチサイズのアルミニウム合金基板を用いて、得られた研磨液組成物の研磨特性の評価を行った。研磨条件及び評価方法は以下の通りである。
【００４５】
＜両面研磨機の設定条件＞
研磨試験機：スピードファム社製 ９Ｂ型両面研磨機
研磨パッド：ロデール・ニッタ社製 ポリテックスＤＧ−Ｈ
定盤回転数：５０r/min
スラリー供給量：２０ml/min
研磨時間：４分
研磨荷重：７．８ｋＰａ
投入した基板の枚数：１０枚
【００４６】
＜研磨速度＞
研磨前後のアルミニウム合金基板の重量変化より研磨速度を求め、平均粒径（Ｄ５０）が１０５ｎｍのコロイダルシリカで研磨した比較例２の研磨液組成物の研磨速度を基準とした相対値（相対研磨速度）を求めた。その結果を併せて表３に示す。
【００４７】
＜表面粗さの測定＞
ランク・テーラーホブソン社製 タリーステップを用いて、以下の条件で中心線表面粗さ（Ｒａ）を測定した。その結果を表３に示す。
触針先端サイズ：２．５μｍ×２．５μｍ
ハイパスフィルター：８０μｍ
測定長さ：０．６４ｍｍ
【００４８】
＜スクラッチの測定＞
光学顕微鏡観察（微分干渉顕微鏡）を用いて倍率２００倍で各基板の表面を６０度おきに６カ所測定した。スクラッチの深さは原子間力顕微鏡（ＡＦＭ：デジタルインスツルメント社製 ＮａｎｏｓｃｏｐｅIII ）によって測定した。その結果を表３に示す。
【００４９】
＜ピットの測定＞
光学顕微鏡観察（微分干渉顕微鏡）を用いて倍率200 倍で各基板の表面を３０度おきに１２カ所測定し、１２視野あたりのピット数を数えた。その結果を表３に示す。
【００５０】
評価基準
表３に記載の研磨液組成物により研磨された基板について、各項目の平均値を求め下記の基準により評価を行った。
表面粗さ（Ｒａ） ◎：２Å以下 ○：３Å以下 ×：３Åを越える
スクラッチ ○：０．５本以下 ×：０．５本を越える
ピット ○：３個／面以下 ×：３個／面を越える
【００５１】
【表３】

【００５２】
表３の結果より、実施例１〜５で得られた研磨液組成物は、比較例１〜５で得られた研磨液組成物に比べ、研磨速度が向上し、得られた被研磨物の表面平滑性にも優れ、スクラッチ、ピット等の表面欠陥もないものであることがわかる。
【００５３】
【発明の効果】
本発明により、突起や研磨傷等の表面欠陥が少なく、表面粗さに代表される表面平滑性が向上したメモリーハードディスク、半導体素子等の精密部品用基板を効率よく製造することができる。
【図面の簡単な説明】
【図１】図１は、実施例１で用いた研磨材の走査型電子顕微鏡写真を示す図である。
【図２】図２は、比較例１で用いた研磨材の走査型電子顕微鏡写真を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing liquid composition, a polishing method for a substrate to be polished using the polishing liquid composition, and a method for manufacturing a substrate using the polishing liquid composition.
[0002]
[Prior art]
With the recent increase in magnetic recording density, the flying height of the magnetic head on the memory magnetic disk when reading and writing magnetic information is becoming increasingly lower. As a result, the surface polishing process in the manufacturing process of the magnetic disk substrate is excellent in surface smoothness [for example, surface roughness (Ra) and waviness (wa)], and there are no surface defects such as protrusions, scratches, pits, etc. There is a demand for manufacturing a highly accurate disk surface that can cause a low flying height of the head without causing an error in writing / reading magnetic information due to surface defects.
[0003]
Also in the semiconductor field, the miniaturization of wiring is progressing along with higher integration of circuits and higher operating frequency. Also in the manufacturing process of a semiconductor device, when the photoresist is exposed, the depth of focus becomes shallow with the miniaturization of the wiring, so that further smoothing of the pattern forming surface is desired.
[0004]
However, the abrasives produced by pulverization that have been used in the past have polishing scratches on the surface to be polished due to coarse particles remaining in the abrasive, so that the surface quality excellent in surface smoothness as described above is obtained. There is a drawback that it is difficult to polish while maintaining.
[0005]
For this reason, colloidal silica with a narrow particle size distribution and less coarse particles is used. However, in polishing with colloidal silica, it is relatively easy to achieve the required high surface accuracy, but because the particle size is fine, the polishing rate is slow and the desired surface accuracy cannot be obtained in a short time. There are drawbacks.
[0006]
Therefore, as a method for improving the polishing rate, improvement of the polishing rate by using various additives has been proposed, but all of them have been insufficient to achieve a satisfactory polishing rate.
[0007]
[Problems to be solved by the invention]
An object of the present invention is excellent in surface smoothness of a polished object after polishing and for generating surface defects such as protrusions and polishing scratches for economical polishing of a memory hard disk and for polishing a semiconductor element, and is economical. An object of the present invention is to provide a polishing composition capable of polishing at a high speed, a polishing method for a substrate to be polished using the polishing composition, and a method for producing a substrate using the polishing composition.
[0008]
[Means for Solving the Problems]
That is, the gist of the present invention is as follows.
[1] A polishing composition comprising a mixture of two or more colloidal silicas having different particle diameters (D50) with an integrated particle diameter distribution (number basis) from the small particle diameter side of 50% and water. The ratio (D50L / D50S) of D50 (D50L) of the abrasive material (B) having the largest D50 to D50 (D50S) of the abrasive material (A) having the smallest D50 is 1.1 to 3.0, and A polishing liquid composition having a blending ratio with B (A / B (weight ratio)) of 90/10 to 10/90,
[2] The polishing method of a substrate to be polished polishing the substrate by using the polishing composition of the above [1] Symbol mounting, and (3) by using the polishing composition of the above [1] Symbol placement, the The present invention relates to a substrate manufacturing method including a step of polishing a polishing substrate.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
As the polishing liquid composition of the present invention, as described above,
(Aspect 1) A polishing composition comprising a mixture of an abrasive and water, wherein the cumulative particle size distribution (number basis) from the small particle size side is 50% in the particle size distribution of the abrasive. The ratio (D90 / D50) of the particle size (D90) at which the cumulative particle size distribution (number basis) from the small particle size side to the particle size (D50) becomes 90% is 1.3 to 3.0, and (2) A polishing composition having a D50 of 10 to 600 nm, and (Aspect 2) A polishing composition comprising a mixture of two or more kinds of abrasives having different D50 and water, and having the smallest polishing D50 The ratio (D50L / D50S) of D50 (D50L) of the abrasive (B) having the largest D50 to D50 (D50S) of the material (A) is 1.1 to 3.0, and the blending ratio of A and B ( Two embodiments of the polishing composition having A / B (weight ratio) of 90/10 to 10/90 And the like.
[0010]
In the polishing composition of aspect 1, (1) the ratio of D90 to D50 (D90 / D50) is 1.3 to 3.0, and (2) the abrasive having a particle size distribution in which D50 is 10 to 600 nm. The surface roughness of the substrate to be polished after polishing is small, and the substrate to be polished can be polished at an economical speed without generating surface defects such as protrusions and polishing scratches. The effect is expressed.
[0011]
Regarding the particle size distribution of the abrasive of this embodiment, from the viewpoint of achieving a smoother and better surface quality, such as prevention of scratching and reduction of surface roughness (Ra), and from the viewpoint of achieving a high polishing rate, D90 / D50. Is 1.3 to 3.0, preferably 1.3 to 2.0. Further, D90 / D50 is 1.3 or more from the viewpoint of achieving a high polishing rate, and 3.0 or less from the viewpoint of maintaining a high polishing rate and obtaining good surface smoothness.
[0012]
D50 of the abrasive | polishing material used for this aspect is 10-600 nm, Preferably it is 30-200 nm, Most preferably, it is 40-100 nm. The D50 is 10 nm or more from the viewpoint of obtaining a high polishing rate, and is 600 nm or less from the viewpoint of preventing occurrence of surface defects such as scratches and obtaining good surface smoothness.
[0013]
In this embodiment, in order to obtain a substrate to be polished having a high polishing rate and excellent surface smoothness, the particle size (D10) at which the integrated particle size distribution serving as an index of distribution on the small particle size side is 10%. Is preferably 5 to 100 nm, more preferably 15 to 85 nm, still more preferably 35 to 70 nm, and particularly preferably 40 to 60 nm. D10 is preferably 5 nm or more from the viewpoint of obtaining a high polishing rate, and is preferably 100 nm or less from the viewpoint of maintaining good surface smoothness.
[0014]
In this embodiment, two or more kinds of abrasives may be used in combination. In this case, the particle size distributions (D10, D50, D90) are all measured for the mixed abrasive.
[0015]
Next, in the polishing liquid composition of aspect 2, two or more kinds of abrasives having different D50 are contained, and the abrasive having the largest D50 with respect to D50 (D50S) of the abrasive having the smallest D50 (A) (B ) D50 (D50L) ratio (D50L / D50S) is 1.1 to 3.0, and the blending ratio of A and B (A / B (weight ratio)) is 90/10 to 10/90. There is one major feature in this point. By using such an abrasive, the surface roughness of the substrate to be polished after polishing is small, and the surface of the substrate to be polished is polished without generating surface defects such as protrusions and polishing scratches. There is an advantage that a particularly excellent polishing rate can be obtained. Here, when three or more kinds of abrasives having different D50s are used, D50 of the abrasive having the smallest D50 is defined as “D50S”, and D50 of the abrasive having the largest D50 is defined as “D50L”.
[0016]
D50L / D50S of this aspect is 1.1-3.0, Preferably it is 1.5-3.0. D50L / D50S is 1.1 or more from the viewpoint of improving the polishing rate, and also maintains a high polishing rate and maintains good surface smoothness without generating surface defects such as scratches. 3.0 or less. In the polishing composition of this aspect, the mixing ratio of two or more kinds of abrasives preferably satisfies the ratio of D90 and D50 in the particle size distribution after blending, 1.3 to 3.0, It is preferable that D50 is 10 to 600 nm. Furthermore, it is preferable that D10 is 5 to 100 nm. In addition, the compounding ratio (A / B: weight ratio) of the abrasive (A) having the smallest D50 and the abrasive (B) having the largest D50 is 90/10 to 10/90, preferably 90/10 to 20 / 80, more preferably 85/15 to 35/65.
[0017]
In this embodiment, if there are two or more kinds of abrasives used, the kind of each abrasive may be the same or different. The above D50L and D50S are both before mixing.
[0018]
In addition, the particle size of the abrasive in modes 1 and 2 can be determined by the following method using a scanning electron microscope (hereinafter referred to as SEM). That is, the polishing composition containing the abrasive is diluted with ethanol so that the abrasive concentration is 0.5% by weight. This diluted solution is uniformly applied to a sample stage for SEM heated to about 50 ° C. Thereafter, the excess solution is blotted with a filter paper and uniformly dried naturally so that the solution does not aggregate.
[0019]
Pt-Pd is vapor-deposited on a naturally-dried abrasive, and about 500 abrasives in the field of view 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 particles can be observed, and two points are observed on one sample stage, and a photograph is taken. The photographed photograph (4 inches × 5 inches) is enlarged to A4 size by a copying machine or the like, and the particle diameters of all photographed abrasives are measured and counted by calipers or the like. This operation is repeated several times so that the number of abrasives to be measured 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 aggregated, and the frequency (%) is added in order from the smallest particle diameter, the particle diameter at which the value is 10% is D10, the particle diameter at 50% is D50, the particle diameter at 90% D90 can be used to determine the number-based particle size distribution in the present invention. In addition, the particle size distribution here is calculated | required as a particle size distribution of a primary particle. However, when there are secondary particles in which primary particles such as aluminum oxide, cerium oxide, and fumed silica are fused, the particle size distribution can be obtained based on the particle size of the secondary particles. .
[0020]
Further, the method for adjusting the particle size distribution of the abrasive is not particularly limited. For example, when the abrasive is colloidal silica, the final particle is added by adding new core particles during the particle growth process in the production stage. It can also be achieved by a method of giving the product a particle size distribution or a method of mixing two or more abrasives having different particle size distributions.
[0021]
The abrasive used in the polishing composition of the present invention shown in the first aspect and the second aspect may be an abrasive generally used for polishing. Examples of the abrasive include metal; metal or metalloid carbide, nitride, oxide, boride; diamond and the like. The metal or metalloid element is derived from the 2A, 2B, 3A, 3B, 4A, 4B, 5A, 6A, 7A or 8A group of the periodic table (long period type). Specific examples of the abrasive include aluminum oxide, silicon carbide, diamond, magnesium oxide, zinc oxide, titanium oxide, cerium oxide, zirconium oxide, colloidal silica, and fumed silica. Among these, aluminum oxide, colloidal silica, fumed silica, cerium oxide, zirconium oxide, titanium oxide, and the like are suitable for polishing precision component substrates such as semiconductor wafers, semiconductor elements, and magnetic recording medium substrates. As for aluminum oxide, various crystal systems such as α and γ are known, but can be appropriately selected and used depending on the application. Among these, colloidal silica is particularly preferable because it is suitable for the final polishing application of a high recording density memory magnetic disk substrate requiring higher smoothness and the polishing application of a semiconductor substrate.
[0022]
The content of the abrasive in the polishing composition is preferably 0.5% by weight or more, more preferably 1% by weight or more, still more preferably 3% by weight or more, and particularly preferably 5% from the viewpoint of improving the polishing rate. It is 50% by weight or less, more preferably 40% by weight or less, still more preferably 30% by weight or less, and particularly preferably 25% by weight or less from the viewpoint of improving the surface quality and economical efficiency. That is, the content is preferably 0.5 to 50% by weight, more preferably 1 to 40% by weight, still more preferably 3 to 30% by weight, and particularly preferably 5 to 25% by weight.
[0023]
Water in the polishing composition is used as a medium, and the content thereof is preferably 50 to 99.5% by weight, more preferably 60 to 99% by weight from the viewpoint of efficiently polishing the object to be polished. %, More preferably 70 to 97% by weight, particularly preferably 75 to 95% by weight.
[0024]
Moreover, other components can be mix | blended with the polishing liquid composition of this invention as needed. Examples of the other components include metal salts, ammonium salts or amine salts of monomeric acid compounds, peroxides, thickeners, dispersants, rust inhibitors, basic substances, and surfactants. Specific examples of monomeric acid compound metal salts, ammonium salts, amine salts and peroxides are disclosed in JP-A 62-25187, page 2, right upper column, lines 3 to 11, JP-A 63-251163. Japanese Laid-Open Patent Publication No. 2-lower left column 6 lines to 13 lines, Japanese Patent Laid-Open No. 1-205973, page 3, upper left column 4 lines to upper right column 2 lines, Japanese Patent Application Laid-Open No. 3-115383, page 2 lower right column 16 lines to page 3 upper left column 11 No. 4, JP-A-4-275387, page 2, right column, line 27 to page 3, left column, line 12 and lines 17 to 23.
[0025]
Further, as a polishing accelerator, a chelate compound having a multidentate ligand capable of binding to a metal ion to form a complex can be blended. Specific examples of the chelate compound include those described in JP-A-4-363385, page 2, right column, lines 21 to 29. Among these, iron (III) salts are preferable, and ethylenediaminetetraacetic acid-iron salts and diethylenetriaminepentaacetic acid-iron salts are particularly preferable.
[0026]
These components may be used alone or in combination of two or more. Further, the content is preferably 0.05 to 20% by weight, more preferably 0.05 in the polishing composition from the viewpoint of improving the polishing rate, the viewpoint of developing each function, and the viewpoint of economy. -10 wt%, more preferably 0.05-5 wt%.
[0027]
The concentration of each component in the polishing liquid composition may be any of the concentration during production of the composition and the concentration during use. Usually, the composition is produced as a concentrated liquid, and it is often used after being diluted at the time of use.
[0028]
The pH of the polishing composition is preferably determined as appropriate according to the type of the object to be polished and the required quality. For example, the pH of the polishing composition is preferably 2 to 12 from the viewpoints of substrate cleaning properties, corrosion resistance of processing machines, and operator safety. In addition, when the object to be polished is a precision component substrate mainly made of a metal such as a Ni-P plated aluminum alloy substrate, 2 to 9 is more preferable from the viewpoint of improving the polishing rate and improving the surface quality. 3 to 8 are particularly preferable. Further, when used for polishing a semiconductor wafer, a semiconductor element, etc., particularly for polishing a silicon substrate, a polysilicon film, a SiO ₂ film, etc., 7 to 12 are preferable from the viewpoint of improving the polishing rate and improving the surface quality. ~ 12 are more preferable, and 9-11 are particularly preferable. The pH can be adjusted by blending a basic substance such as an inorganic acid such as nitric acid or sulfuric acid, an organic acid, ammonia, sodium hydroxide, or potassium hydroxide in a desired amount as necessary.
[0029]
The polishing method of the substrate to be polished according to the present invention is prepared by using the polishing liquid composition of the present invention or by mixing each component so as to be the composition of the polishing liquid composition of the present invention to prepare a polishing liquid. A step of polishing the substrate. As an example of the polishing method, the substrate is sandwiched by a polishing machine with a non-woven organic polymer polishing cloth or the like attached thereto, the polishing composition is supplied to the polishing surface, and the polishing machine or substrate is applied while applying a certain pressure. For example, a method of polishing by moving. In the polishing method of the present invention, by using the polishing liquid composition of the present invention, the polishing rate can be improved, the occurrence of surface defects such as scratches and pits can be suppressed, and the surface roughness (Ra) can be reduced. In particular, a substrate for precision parts can be preferably manufactured.
[0030]
Moreover, the manufacturing method of the board | substrate of this invention has the process of grind | polishing a to-be-polished liquid board | substrate using the polishing liquid composition of this invention.
[0031]
The material of the object to be polished typified by the substrate to be polished is, for example, a metal or semi-metal such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, an alloy mainly composed of these metals, 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 nitride, and resins such as polyimide resin. Of these, a substrate made of a Ni—P plated aluminum alloy or a glass substrate such as crystallized glass or tempered glass is more preferred, and a substrate made of a Ni—P plated aluminum alloy is particularly preferred.
[0032]
The shape of these objects to be polished is not particularly limited. For example, a shape having a flat portion such as a disk shape, a plate shape, a slab shape, or a prism shape, or a shape having a curved surface portion such as a lens can be polished according to the present invention. It becomes the object of polishing using the liquid composition. Among these, it is particularly excellent for polishing a disk-shaped workpiece.
[0033]
The polishing composition of the present invention is suitably used for polishing precision component substrates. For example, it is suitable for polishing a substrate of a magnetic recording medium such as a magnetic disk, an optical disk, and a magneto-optical disk, a photomask substrate, an optical lens, an optical mirror, an optical prism, and a semiconductor substrate. Polishing of a semiconductor substrate includes polishing performed in a silicon wafer (bare wafer) polishing process, a buried element isolation film forming process, an interlayer insulating film flattening process, a buried metal wiring forming process, a buried capacitor forming process, and the like. The polishing composition of the present invention is particularly suitable for polishing a magnetic disk substrate. Furthermore, it is suitable for obtaining a magnetic disk substrate having a surface roughness (Ra) of 3 mm or less. In the present specification, the surface roughness (Ra) is obtained as a generally-described centerline roughness, and the centerline average roughness obtained from a roughness curve having a wavelength component of 80 μm or less is represented by Ra. This can be measured as follows.
[0034]
Centerline average roughness (Ra)
Using a tally step manufactured by Rank Taylor Hobson, measure under the following conditions.
Tip size of stylus: 2.5 μm × 2.5 μm
High-pass filter: 80 μm
Measurement length: 0.64mm
[0035]
The method for producing a substrate of the present invention includes 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 preferred that For example, a substrate made of a Ni—P plated aluminum alloy having a surface roughness (Ra) adjusted to 5 to 15 mm by a one-step or two-step polishing step is polished using the polishing composition of the present invention. By polishing according to the process, a magnetic disk substrate having a surface roughness (Ra) of 3 mm or less, preferably a magnetic disk substrate having a surface roughness (Ra) of 2.5 mm or less can be produced.
[0036]
In particular, the polishing composition of the present invention can be used to produce a magnetic disk substrate having a surface roughness (Ra) of 3 mm or less, preferably a magnetic disk substrate having a surface roughness (Ra) of 2.5 mm or less by two-step polishing. It is suitable for being used in the second step.
[0037]
The manufactured substrate is excellent in surface smoothness. For example, in the case of a magnetic disk substrate, as its surface smoothness, the surface roughness (Ra) is desirably 3 mm or less, preferably 2.5 mm or less. Further, the substrate is substantially free from surface defects.
[0038]
As described above, the use of the polishing composition of the present invention improves the polishing rate, reduces surface defects such as scratches and pits, and improves the smoothness such as surface roughness (Ra). High-quality magnetic disk substrates excellent in production can be produced with high production efficiency.
[0039]
The polishing composition of the present invention is particularly effective in the polishing process, but can be similarly applied to other polishing processes such as a lapping process.
[0040]
【Example】
Examples 1-5 and Comparative Examples 1-5
As an abrasive, a scanning electron microscope (S-4000 model manufactured by Hitachi, Ltd.) was used, and the cumulative particle diameter (D10, calculated by the method described in the detailed description of the invention (particle diameter measured with calipers)) Colloidal silica (D50 and D90) having the characteristics shown in Table 1 (shown as abrasives A to E in Tables 1 and 2) was used. A scanning electron micrograph (magnification 50000 times) of the abrasive used in Example 1 is shown in FIG. 1, and a scanning electron micrograph (magnification 50000 times) of the abrasive used in Comparative Example 1 is shown in FIG. Show.
[0041]
[Table 1]

[0042]
In order to obtain the polishing composition having the particle size distribution of the present invention, it was blended at a ratio shown in Table 2 so that the abrasive concentration was 25% by weight, and EDTA-Fe salt (Cyrest ( Co., Ltd., trade name: Kirest Fe) 3% by weight, and the remaining ion-exchanged water were added and mixed to prepare a polishing composition.
[0043]
[Table 2]

[0044]
As the substrate to be polished, a Ni—P plated surface roughness Ra = 15 mm, a thickness: 0.8 mm, and a 3.5 inch diameter aluminum alloy substrate, the polishing characteristics of the obtained polishing composition were used. Evaluation was performed. Polishing conditions and evaluation methods are as follows.
[0045]
<Setting conditions of double-side polishing machine>
Polishing test machine: 9B type double-side polishing machine made by Speed Fam Co., Ltd. Polishing pad: Polytex DG-H made by Rodel Nitta
Plate rotation speed: 50r / min
Slurry supply amount: 20 ml / min
Polishing time: 4 minutes Polishing load: 7.8 kPa
Number of substrates loaded: 10 [0046]
<Polishing speed>
The polishing rate was determined from the change in weight of the aluminum alloy substrate before and after polishing, and the relative value (relative polishing rate) based on the polishing rate of the polishing composition of Comparative Example 2 polished with colloidal silica having an average particle size (D50) of 105 nm. ) The results are also shown in Table 3.
[0047]
<Measurement of surface roughness>
Using a tally step manufactured by Rank Taylor Hobson, the centerline surface roughness (Ra) was measured under the following conditions. The results are shown in Table 3.
Tip size of stylus: 2.5 μm × 2.5 μm
High-pass filter: 80 μm
Measurement length: 0.64mm
[0048]
<Measurement of scratch>
Using an optical microscope observation (differential interference microscope), the surface of each substrate was measured at 60 points every 60 degrees at a magnification of 200 times. The depth of the scratch was measured by an atomic force microscope (AFM: Nanoscope III manufactured by Digital Instruments). The results are shown in Table 3.
[0049]
<Measurement of pits>
Using an optical microscope observation (differential interference microscope), the surface of each substrate was measured at 30 positions every 200 degrees at a magnification of 200 times, and the number of pits per 12 fields of view was counted. The results are shown in Table 3.
[0050]
For the substrates polished with the polishing composition described in Evaluation Criteria 3, the average value of each item was determined and evaluated according to the following criteria.
Surface roughness (Ra) ◎: 2 mm or less ○: 3 mm or less ×: Scratch exceeding 3 mm ○: 0.5 or less ×: Pit exceeding 0.5 ×: 3 / surface or less ×: 3 / surface [0051]
[Table 3]

[0052]
From the results of Table 3, the polishing liquid compositions obtained in Examples 1 to 5 were improved in polishing rate as compared with the polishing liquid compositions obtained in Comparative Examples 1 to 5, and It can be seen that it is excellent in surface smoothness and has no surface defects such as scratches and pits.
[0053]
【The invention's effect】
According to the present invention, it is possible to efficiently manufacture a substrate for precision parts such as a memory hard disk and a semiconductor element having few surface defects such as protrusions and polishing scratches and improved surface smoothness represented by surface roughness.
[Brief description of the drawings]
FIG. 1 is a view showing a scanning electron micrograph of an abrasive used in Example 1. FIG.
2 is a scanning electron micrograph of the abrasive used in Comparative Example 1. FIG.

Claims (3)

A polishing composition comprising a mixture of two or more colloidal silicas having different particle diameters (D50) with an integrated particle size distribution (number basis) from the small particle diameter side of 50% and water, The ratio (D50L / D50S) of D50 (D50L) of the abrasive (B) having the largest D50 to D50 (D50S) of the smallest abrasive (A) is 1.5 to 3.0, and A polishing composition having a blending ratio (A / B (weight ratio)) of 90/10 to 10/90. Polished substrate polishing method for polishing a substrate to be polished by using the polishing composition according to claim 1 Symbol placement. By using the polishing composition according to claim 1 Symbol mounting method of manufacturing a substrate having a step of polishing the substrate.

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