JP2003306669A - Polishing slurry - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new polishing slurry by which the surface of a polishing object comprising an oxide single crystal or silicon dioxide is polished to the smooth and flat surface within a shorter time. <P>SOLUTION: The polishing slurry is constituted of water, polishing particles and a polishing accelerator, and acidity or alkalinity of the slurry is the acidity. The pH of the slurry is 2-5. An organic acid or an organic acid salt is used as the polishing accelerator. Phthalic acid is used as the organic acid, and phthalic acid salt is used as the organic acid salt. Preferably, potassium hydrogen phthalate is suitably used. The polishing of the polishing object W is carried out by holding the polishing object W by a holder 13, and pushing the surface of the polishing object W held by the holder 13 to the surface of a pad 11 of a level block 12 while rotating the level block 12 and the holder 13 in the directions of R and r respectively, and feeding the polishing slurry through a nozzle 14 to the surface of the pad 11 on the level plate 12. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silicon wafer,
The present invention relates to a polishing slurry suitable for polishing the surface of an object to be polished such as a ferroelectric wafer, a glass substrate for a magnetic hard disk or a liquid crystal color filter, which requires high smoothness and flatness.

[0002]

2. Description of the Related Art Telephones,
Parts such as a semiconductor device, a magnetic disk, and a liquid crystal display (LCD) are widely used in electronic devices such as cameras and computers for controlling functions and storing and displaying information.

Surfaces of semiconductor wafers, magnetic hard disk substrates, glass substrates for TFT liquid crystal panels, color filters, etc., which are substrates for such components, are subjected to a polishing process, then a multilayer wiring process, a coating process, etc. It is commercialized through various processes required in the manufacturing process and further inspection process.

The various processes required in the manufacturing stage, such as the wiring and the coating applied to the surface of the substrate, bring out the performance and function of the parts planned in the design stage, so that the accuracy in nanometer units is required. For this reason,
High precision is required for each process, and even in the polishing process,
It is required to polish the surface of the substrate to a smooth and flat surface.

For example, although a silicon wafer is widely used as a semiconductor wafer which is a substrate of a semiconductor device,
In recent years, surface acoustic wave devices and electro-optical devices have come to be used in wireless communication devices such as mobile phones and car phones and optical devices such as digital cameras. As a substrate for such components, lithium tantalate, A ferroelectric wafer made of an oxide single crystal such as lithium niobate is used.

A magnetic hard disk is widely used as a storage medium for computers. In this magnetic hard disk, the surface of a non-magnetic substrate is polished to be smooth and flat, and then electroless plating is performed on the Ni-P film to form a Ni-P film, which is then textured and further sputtered. The magnetic film and the protective film are formed by using the film forming technique of. As a non-magnetic substrate, a glass substrate made of silicon dioxide (quartz glass or quartz glass) is widely used in addition to an aluminum alloy. This is because the glass substrate has excellent flatness and parallelism.

Further, in a liquid crystal display device such as a computer and a mobile phone, a TFT liquid crystal panel in which electrodes and transistors are formed on a glass substrate, an alignment film is formed on the electrodes and transistors, and the surface of the alignment film is rubbed is used. Also, a color filter is used in which a pigment resist is coated on a glass substrate, exposure, development and resist removal are repeated to form three colors, and an alignment film is formed on it, and the surface of this alignment film is rubbed. Has been done. As described above, a glass substrate made of silicon dioxide (quartz glass or quartz glass) is used as a substrate for a TFT liquid crystal panel or a color filter.

As described above, the surface of the substrate of each of the above-mentioned components (hereinafter referred to as the object to be polished) is required to have high smoothness and flatness. Generally, loose abrasive grains are used. The polishing with the loose abrasive grains is roughly classified into tape polishing and pad polishing.

In tape polishing, an object to be polished is rotated, a polishing slurry is supplied to the surface of the object to be polished, and a suede, a woven sheet, a non-woven sheet, a flocked sheet or a foam sheet is formed into a tape. This is performed by pressing the cut abrasive tape and feeding it continuously or intermittently.

For pad polishing, a surface plate having a polishing pad formed by cutting a suede cloth, a woven sheet, a non-woven sheet, a flocked sheet or a foam sheet into a pad shape is rotated, and the polishing slurry is applied to the surface of the polishing pad. Supply,
The surface of the object to be polished is pressed onto this, and this is rotated.

As the polishing slurry, one or more kinds of polishing particles selected from silica, alumina, ceria, manganese oxide, and zirconia are dispersed in water or an aqueous solution containing glycols, alcohols and the like. Stuff used.

Here, in order to polish the surface of the object to be polished to a smooth and flat surface, the average particle size of the polishing particles is about 10
nm to 300 nm.

In order to reduce the time required to polish the surface of the object to be polished, a polishing slurry to which a polishing accelerator that reacts with the surface of the object to be polished is added is used. Are chemically and mechanically polished (for example, JP-A-2000-73049 and JP-A-2001).
-93866).

Such a polishing accelerator can be appropriately selected according to the material constituting the surface of the object to be polished.

For example, when the material forming the surface of the object to be polished is silicon dioxide, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, hydrofluoric acid,
Fluoride or the like is used. Further, when the surface of the object to be polished is an oxide single crystal, salts such as carbonic acid, boric acid, phosphoric acid, citric acid, oxalic acid, tartaric acid and potassium fluoride, potassium nitrate, potassium hydroxide, sodium hydroxide, tetra Methyl ammonium, ethylenediamine tetrairon acetate 2 ammonium, etc. are used.

The liquidity of the polishing slurry to which such a polishing accelerator has been added is neutral to pH 6-11 and alkaline.

However, with such a conventional polishing slurry, the surface of the object to be polished can be polished to a substantially smooth and flat surface, but the present situation is that the polishing time cannot be sufficiently shortened.

Therefore, in the field of polishing technology,
The development of a new polishing technique capable of polishing the surface of an object to be polished made of an oxide single crystal or silicon dioxide into a smooth and flat surface in a shorter time is a technical issue.

The present invention has been made to solve such a technical problem, and therefore, an object of the present invention is to improve the surface of an object to be polished made of an oxide single crystal or silicon dioxide. It is to provide a novel polishing slurry capable of polishing a smooth and flat surface in a short time.

[0020]

DISCLOSURE OF THE INVENTION The present invention is directed to a polishing object such as a silicon wafer, a ferroelectric wafer, a glass substrate for a magnetic hard disk or a liquid crystal display device, the surface of which is required to have high smoothness and flatness. A polishing slurry suitable for polishing the surface with loose abrasive grains.

The polishing slurry of the present invention contains water, abrasive particles,
In order to achieve the above object, in the present invention, an organic acid or an organic acid salt is used as the polishing accelerator, and the liquidity of the polishing slurry of the present invention is acidic (pH 2 to 5). Is.

As the organic acid, phthalic acid, lactic acid, acetic acid, malic acid, succinic acid, benzoic acid, quinaldic acid and glycine are used.

Phthalate is used as the organic acid salt. Here, as the phthalate, disodium phthalate, potassium hydrogen phthalate, potassium sodium phthalate, diammonium phthalate, ammonium hydrogen phthalate, disodium phthalate, or sodium hydrogen phthalate is used. Preferably potassium hydrogen phthalate is used.

As the abrasive particles, one or more kinds of particles selected from silica, alumina, ceria, manganese oxide, and zirconia are used. Suitably, the average particle size of the particles is selected from the range of 10 nm to 100 nm.

The concentration of abrasive particles in the polishing slurry is 3%.
The concentration of the polishing accelerator in the polishing slurry is in the range of 0.01% to 10%.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, the surface of an object to be polished such as a silicon wafer, a ferroelectric wafer, a glass substrate for a magnetic hard disk or a liquid crystal display device, which is required to have high smoothness and flatness, is used. It is a polishing slurry suitable for polishing.

The polishing slurry of the present invention contains water, abrasive particles,
And a polishing accelerator, and an organic acid or an organic acid salt is used as the polishing accelerator. The liquidity of the polishing slurry of the present invention is acidic (pH 2 to 5).

As the organic acid, phthalic acid, lactic acid, acetic acid, malic acid, succinic acid, benzoic acid, quinaldic acid, glycine are used.

Phthalates are used as organic acid salts. Here, as the phthalate, disodium phthalate, potassium hydrogen phthalate, potassium sodium phthalate, diammonium phthalate, ammonium hydrogen phthalate, disodium phthalate, or sodium hydrogen phthalate is used. Preferably potassium hydrogen phthalate is used.

As the abrasive particles, one or more kinds of particles selected from silica, alumina, ceria, manganese oxide, and zirconia are used. The average particle size of the particles is selected from the range of 1 nm to 300 nm, and preferably,
It is selected from the range of 10 nm to 100 nm.

The concentration of abrasive particles in the polishing slurry is 3%.
The concentration of the polishing accelerator in the polishing slurry is in the range of 0.01% to 10%.

<Polishing Method> The polishing according to the present invention is performed by free abrasive grains, and is performed by tape polishing or pad polishing. Pad polishing is preferably performed using the polishing apparatus shown in FIG. 1 for polishing the pad.

The illustrated polishing apparatus 10 has a pad 11 on the surface.
Surface plate 12 to which is attached, a holding tool 13 for holding the polishing object W and pressing the polishing object W against the surface of the pad 11 of the surface plate 12, and the polishing slurry for the pad 1 of the surface plate 12.
It is composed of a nozzle 14 for supplying to the surface of 1.

To polish the object W to be polished, the object W to be polished is held on the holder 13, and the surface plate 12 and the holder 13 are rotated in the same direction (the directions of arrows R and r in the drawing) while the nozzle 14 is being rotated. While the polishing slurry of the present invention is supplied to the surface of the pad 11 on the surface plate 12 through the above, the surface of the polishing object W held by the holder 13 is pressed against the surface of the pad 11 on the surface plate 12.

<Example> A polishing slurry of the present invention was produced. The polishing slurries of the examples had an average particle size of 8
Colloidal silica in which spherical silica particles of 0 nm were dispersed was added to pure water, and potassium hydrogen phthalate was further added to manufacture. The composition of the polishing slurry of the example is as shown in Table 1 below. The liquid properties of the polishing slurries of Examples were pH 4.0 (acidic) as shown in Table 1 below.

[Table 1]

Comparative Example 1 The polishing slurry of Comparative Example 1 was prepared by adding colloidal silica prepared by previously dispersing spherical silica particles having an average particle size of 80 nm in water to water, and further adding ethylenediamine tetrairon acetate 2 ammonium. Manufactured. The composition of the polishing slurry of Comparative Example 1 is as shown in Table 2 below. The liquidity of the polishing slurry of Comparative Example 1 was pH 8.0 (weakly alkaline) as shown in Table 2 below.

[Table 2]

Comparative Example 2 The polishing slurry of Comparative Example 2 was produced by adding colloidal silica prepared by previously dispersing spherical silica particles having an average particle size of 80 nm in water to water, and further adding 3 potassium citrate. . The composition of the polishing slurry of Comparative Example 2 is as shown in Table 3 below. The liquid properties of the polishing slurry of Comparative Example 2 are as shown in Table 3 below.
The pH was 10.0 (alkaline).

[Table 3]

<Comparative Example 3> As the polishing slurry of Comparative Example 3, a commercially available polishing slurry (trade name: Compol 80, which is obtained by adding sodium hydroxide to a colloidal silica slurry in which spherical silica particles having an average particle diameter of 80 nm are dispersed) is used.
Fujimi Co., Ltd. was used. Comparative Example 3
The composition of the polishing slurry is as shown in Table 4 below, and the ratio of each constituent is unknown because it is a commercial product. Comparative Example 3
As shown in Table 4 below, the liquid properties of the polishing slurry of
It was H10.0 (alkaline).

[Table 4]

<Comparative Example 4> The polishing slurry of Comparative Example 4 was produced by adding colloidal silica in which spherical silica particles having an average particle diameter of 80 nm were previously dispersed in water to water, and further adding potassium fluoride. The composition of the polishing slurry of Comparative Example 4 is as shown in Table 5 below. The liquid properties of the polishing slurry of Comparative Example 4 were determined as shown in Table 5 below.
It was 9.0 (alkaline).

[Table 5]

<Comparative Example 5> The polishing slurry of Comparative Example 5 was produced by adding colloidal silica in which spherical silica particles having an average particle diameter of 80 nm were previously dispersed in water to water, and further adding potassium nitrate. The composition of the polishing slurry of Comparative Example 5 is as shown in Table 6 below. The liquid properties of the polishing slurry of Comparative Example 5 are as shown in Table 3 below.
It was 9.0 (alkaline).

[Table 6]

Comparative Example 6 The polishing slurry of Comparative Example 6 was produced by adding colloidal silica in which spherical silica particles having an average particle size of 80 nm were previously dispersed in water to water and further adding tetramethylammonium. The composition of the polishing slurry of Comparative Example 6 is as shown in Table 7 below.
The liquid property of the polishing slurry of Comparative Example 6 was pH 10.0 (alkaline) as shown in Table 7 below.

[Table 7]

<Comparative Test> Lithium niobate chips (size: length 21.7 mm, width 29.) were prepared using the polishing slurries of the above Examples and the polishing slurries of Comparative Examples 1 to 7.
7 mm) was polished, and a comparative test was performed on the surface roughness after polishing and the polishing rate. Also, using a microscope,
The presence or absence of scratches on the surface after polishing was also examined.

The comparative test was carried out by using a polishing apparatus (product name: SPL-15, Okamoto Machine Tool Mfg. Co., Ltd.) as shown in FIG. 1, and a non-woven pad ( Product name: SUBA600, RODEL
Company) was used. The wafer (lithium niobate chip) was attached to the holder using wax. The polishing conditions were as shown in Table 8 below.

[Table 8]

[Table 9]

As shown in the test results of Table 9 above, when the polishing slurry of the example is used, the surface of the hard lithium niobate chip is smooth and flat as in the case of using the polishing slurry of the comparative example. The surface could be polished, and polishing could be performed at a higher polishing rate than when the polishing slurry of the comparative example was used.

[0045]

Since the present invention is constructed as described above,
The surface of an object to be polished made of an oxide single crystal or silicon dioxide can be polished into a smooth and flat surface in a shorter time.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a polishing apparatus.

[Explanation of symbols]

10 ... Polishing device 11 ... Pad 12: surface plate 13 ... holding tool 14 ... Nozzle R: surface rotation direction r ・ ・ ・ Rotating direction of holder

Claims (9)

[Claims] 1. A polishing slurry used for polishing the surface of an object to be polished with free abrasive grains, which comprises water, abrasive particles, and a polishing accelerator, wherein the polishing accelerator is an organic acid or an organic compound. A polishing slurry in which an acid salt is used and the liquidity of the polishing slurry is acidic. 2. The polishing slurry according to claim 1, wherein phthalic acid, lactic acid, acetic acid, malic acid, succinic acid, benzoic acid, quinaldic acid, or glycine is used as the organic acid. 3. The polishing slurry according to claim 1, wherein a phthalate is used as the organic acid salt. 4. As the phthalate salt, disodium phthalate, potassium hydrogen phthalate, potassium sodium phthalate, diammonium phthalate, ammonium hydrogen phthalate, disodium phthalate, or sodium hydrogen phthalate is used. The polishing slurry according to claim 3. 5. The polishing slurry according to claim 1, wherein one or more particles selected from silica, alumina, ceria, manganese oxide, and zirconia are used as the polishing particles. 6. The average particle diameter of the particles is 10 nm to 10 nm.
The polishing slurry of claim 5, selected from the range of 0 nm. 7. The concentration of the polishing particles in the polishing slurry is in the range of 3% to 60%, and the concentration of the polishing accelerator in the polishing slurry is in the range of 0.01% to 10%. The polishing slurry of claim 1, wherein: 8. The polishing slurry according to claim 1, wherein the pH of the polishing slurry is in the range of 2-5. 9. The surface of the object to be polished is an oxide crystal,
Alternatively, the polishing slurry of claim 1, which is silicon dioxide.