JP4156174B2 - Polishing liquid composition - Google Patents

Description

【００４５】
表１の結果より、実施例１〜５で得られた研磨液組成物は、いずれも比較例１〜２で得られた研磨液組成物より研磨速度が速く、研磨材の残留がなく、得られる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。
【００４６】
【発明の効果】
本発明により、研磨・洗浄後の被研磨基板上に研磨材の残留がなく、さらにスクラッチ、ピット等の表面欠陥が少なく、表面粗さ（Ｒａ）等の表面平滑性が向上したメモリー磁気ディスク基板等の被研磨基板を効率よく製造することができるという効果が奏される。
【図面の簡単な説明】
【図１】図１は、実施例２に用いた研磨材のＦＥ−ＳＥＭ像である。
【図２】図２は、比較例１に用いた研磨材のＦＥ−ＳＥＭ像である。
【図３】図３は、実施例３に用いた研磨材の粒径分布である。
【図４】図４は、比較例１に用いた研磨材の粒径分布である。
【図５】図５は、実施例３の研磨液組成物を用いて研磨した被研磨基板の洗浄した後のＡＦＭ像である。
【図６】図６は、比較例１の研磨液組成物を用いて研磨した被研磨基板の洗浄した後のＡＦＭ像である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing composition, a polishing method for a substrate to be polished using the polishing composition, and a method for manufacturing a substrate.
[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. However, because the particle size is fine, colloidal silica adhering to the plate to be polished in the cleaning process after polishing is easy. However, there is a drawback that it cannot be removed. The abrasive remaining on the substrate to be polished may cause uneven thickness of the magnetic recording layer, and as a result, the magnetic characteristics may become unstable. Further, unstable magnetic characteristics are not preferable because it may cause read / write errors.
[0006]
In order to solve this drawback, various cleaning methods for completely removing the remaining abrasive material have been tried in the cleaning process, but it is still not sufficient. In addition, since it is thought that the atomization of abrasives will further progress in the future, the removal thereof has become an increasingly important issue.
[0007]
[Problems to be solved by the invention]
It is an object of the present invention to maintain the surface smoothness of the substrate to be polished without causing any abrasive material to remain on the substrate to be polished in the cleaning step after polishing, and to generate a surface defect without being economical. An object of the present invention is to provide a polishing liquid composition that can be polished at a high speed, 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.
[0008]
[Means for Solving the Problems]
That is, the gist of the present invention is as follows.
[1] A polishing composition comprising water and an abrasive, and in the particle size distribution of the abrasive, (1) the cumulative particle size distribution (number basis) from the small particle size side at a particle size of 40 nm is 25. %, And (2) a polishing liquid composition having a particle size (D50) of 50 to 600 nm at which the cumulative particle size distribution (number basis) from the small particle size side is 50%,
[2] A polishing method for a substrate to be polished using the polishing liquid composition according to [1], and [3] a substrate to be polished using the polishing liquid composition according to [1]. It is related with the manufacturing method of the board | substrate which has the process of grinding | polishing.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The abrasive used in the present invention 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. Of these, colloidal silica particles are particularly suitable for final polishing applications of high recording density memory magnetic disk substrates and semiconductor substrate polishing applications that require higher smoothness. These abrasives can be used alone or in combination of two or more.
[0010]
With respect to the abrasive, from the viewpoint of reducing the residual amount of abrasive on the substrate to be polished, the cumulative particle size distribution from the small particle size side at a particle size of 40 nm is 25% or less, preferably 15% or less, more preferably It is 10% or less, more preferably 5% or less, and particularly preferably 3% or less. In order to reduce the cumulative particle size distribution from the small particle size side to 25% or less, for example, the content of an abrasive having a particle size of 40 nm or less may be lowered. As a method for reducing the content of abrasives having a particle size of 40 nm or less, colloidal silica containing a small particle size is controlled by controlling the rate of addition of the active sol in the synthesis of colloidal silica grown using silica sol as a nucleus. Can be adjusted. Further, there is no problem in using colloidal silica containing a small particle size product by classification with a centrifuge, for example.
[0011]
On the other hand, from the viewpoint of achieving an economical polishing rate and excellent surface smoothness and achieving a good surface quality free from surface defects, a particle diameter (the cumulative particle diameter distribution from the small particle diameter side becomes 50% ( (Hereinafter also referred to as D50) is 50 to 600 nm, preferably 50 to 200 nm, and more preferably 50 to 150 nm.
[0012]
In the present invention, as described above, in the particle size distribution of the abrasive, (1) the cumulative particle size distribution from the small particle size side in the particle size of 40 nm is 25% or less, and (2) D50 is 50 to 600 nm. There is one big feature in the point, and by using an abrasive having such a particle size distribution, an effect that the abrasive can be easily cleaned from the surface of the object to be polished by normal cleaning is exhibited.
[0013]
Further, from the viewpoint of achieving a good surface quality with a high polishing rate, excellent surface smoothness, and no surface defects, a particle size (hereinafter also referred to as D90) having an integrated particle size distribution of 90% from the small particle size side. The ratio of D50 to D50 (D90 / D50) is preferably 1.3 to 3.0, more preferably 1.3 to 2.0.
[0014]
In addition, the method for adjusting the particle size distribution of the abrasive within the above range is not particularly limited. For example, when the abrasive is colloidal silica, particles that become new nuclei in the process of particle growth in the production stage are used. There is a method of giving the final product a particle size distribution by adding. It can also be achieved by a method of mixing at least two abrasives having different particle size distributions. In this case, it is not necessary that the abrasives are of the same type, and there is no problem in mixing different types of abrasives.
[0015]
The particle size of the abrasive 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.
[0016]
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. .
[0017]
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.
[0018]
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.
[0019]
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.
[0020]
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.
[0021]
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 economical viewpoint. -10 wt%, more preferably 0.05-5 wt%.
[0022]
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.
[0023]
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.
[0024]
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.
[0025]
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.
[0026]
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.
[0027]
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.
[0028]
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.
[0029]
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
[0030]
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.
[0031]
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.
[0032]
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.
[0033]
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.
[0034]
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.
[0035]
【Example】
Examples 1 to 5 and Comparative Examples 1 and 2 (However, Examples 4 and 5 are reference examples)
As the abrasive, a scanning electron microscope (S-4000 model manufactured by Hitachi, Ltd.) was used, and the cumulative particle diameter D50 calculated by the method described in the detailed description of the invention (particle diameter measured with calipers) Using a colloidal silica of 25 to 160 nm, an abrasive having a particle size distribution (integrated particle size distribution at 40 nm, D50, D90 and D50 / D90) shown in Table 1 was prepared as appropriate. After adding and mixing 25 parts by weight of the obtained abrasive and 72 parts by weight of ion-exchanged water, 3 parts by weight of EDTA-Fe salt (manufactured by Kirest Co., Ltd., trade name: Kirest Fe) was further added as a polishing accelerator. A polishing composition was prepared. Further, in Example 2, the abrasive of Comparative Example 2 was subjected to polishing by classifying and removing the abrasive having a small particle diameter using a centrifuge. FIG. 1 shows an FE-SEM image (magnification 50000 times) of the abrasive used in Example 2. FIG. 2 shows an FE-SEM image (50000 times magnification) of the abrasive used in Comparative Example 1. FIG. 3 shows the particle size distribution of the abrasive used in Example 3. FIG. 4 shows the particle size distribution of the abrasive used in Comparative Example 1.
[0036]
Polishing evaluation was performed using a Ni—P plated surface roughness Ra = 15 mm and a thickness: 0.8 mm of an aluminum alloy substrate having a diameter of 3.5 inches as a substrate to be polished. The polishing conditions are as follows.
[0037]
<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 loaded substrates: 10 [0038]
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) was determined based on the polishing rate of Comparative Example 2 polished with colloidal silica having an average particle diameter D50 of 100 nm. The results are also shown in Table 1.
[0039]
<Measurement of polishing material remaining on substrate to be polished>
The polishing material remaining on the substrate to be polished was measured in an area of 2 μm × 2 μm at each of the three sides of the substrate to be polished with Scan rate = 1 Hz using an atomic force microscope (AFM: Nanoscope III manufactured by Digital Instruments). The presence or absence of the remaining abrasive (residual abrasive grains) was measured and confirmed. The results are shown in Table 1. FIG. 5 shows an AFM image after the substrate to be polished polished using the polishing composition of Example 3 is cleaned. FIG. 6 shows an AFM image after the substrate to be polished polished with the polishing composition of Comparative Example 1 was cleaned.
[0040]
<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 1.
Tip size of stylus: 2.5 μm × 2.5 μm
High-pass filter: 80 μm
Measurement length: 0.64mm
[0041]
<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 results are shown in Table 1.
[0042]
<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 1.
[0043]
Evaluation Criteria For the substrates polished with the polishing liquid shown in Table 1, the average value of each item was determined and evaluated according to the following criteria.
Remaining abrasive ○: 5 or less / 2 μm × 2 μm
×: five more than / 2 μm × 2 μm
Surface roughness (Ra) ○: 3 mm or less ×: Scratch exceeding 3 mm ○: 0.5 or less ×: 0.5 or more pits ○: 3 or less or less ×: 3 or more or more [0044]
[Table 1]

[0045]
From the results in Table 1, the polishing liquid compositions obtained in Examples 1 to 5 were faster in polishing rate than the polishing liquid compositions obtained in Comparative Examples 1 and 2, and there was no residual abrasive. It can be seen that the surface to be polished is excellent in surface smoothness and has no surface defects such as scratches and pits.
[0046]
【The invention's effect】
According to the present invention, a memory magnetic disk substrate in which no polishing material remains on the substrate to be polished after polishing and cleaning, surface defects such as scratches and pits are small, and surface smoothness such as surface roughness (Ra) is improved. The effect that the substrate to be polished such as can be efficiently manufactured is exhibited.
[Brief description of the drawings]
FIG. 1 is an FE-SEM image of an abrasive used in Example 2. FIG.
FIG. 2 is an FE-SEM image of an abrasive used in Comparative Example 1.
FIG. 3 is a particle size distribution of an abrasive used in Example 3.
4 is a particle size distribution of an abrasive used in Comparative Example 1. FIG.
5 is an AFM image after cleaning of a substrate to be polished polished with the polishing composition of Example 3. FIG.
6 is an AFM image after cleaning of a substrate to be polished polished with the polishing composition of Comparative Example 1. FIG.

Claims (4)

A polishing composition for a substrate comprising a Ni-P plated aluminum alloy comprising water, colloidal silica and a chelate compound, wherein (1) the particle size distribution of colloidal silica is as follows: The cumulative particle size distribution (number basis) is 3 % or less, and (2) the particle size (D50) at which the cumulative particle size distribution (number basis) from the small particle size side is 50% is 50 to 150 nm. A polishing composition for substrates comprising a Ni-P plated aluminum alloy , characterized in that: 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. Method using the polishing liquid composition of claim 1 Symbol mounting, characterized by polishing the substrate, to produce a reduced substrate of residual abrasives.

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