KR20110042610A - Method for manufacturing polishing-pad containing nano-diamonds, polishing-pad manufactured by the method, and polishing method using the polishing-pad - Google Patents

Abstract

PURPOSE: A method for manufacturing a polishing pad with nano diamonds, a polishing pad manufactured thereby, and a polishing method using the polishing pad are provided to reduce the amount of polishing slurry because polishing particles and nano diamonds are mixed with polyurethane resin. CONSTITUTION: A method for manufacturing a polishing pad with nano diamonds is as follows. Polishing particles and nano diamonds are uniformly scattered and mixed with polyurethane resin. The mixed materials are injected into a mold and are molded in a specific shape. The molded products are dried in a drying machine. A polishing pad is manufactured by thinly slicing the dried products. The polishing surface of the polishing pad is uniformly trimmed by rapidly rotating a buff. The polishing pad is cut with a specific size.

Description

A method for manufacturing a polishing pad comprising nanodiamonds, and a polishing pad manufactured by the method, and a polishing method using the polishing pad `` Method for manufacturing polishing-pad containing nano-diamonds, Polishing-pad manufactured by the method, and Polishing method using the polishing-pad}

The present invention provides a method for manufacturing a polishing pad for securing high polishing speed, flatness and surface roughness in a substrate polishing process for polishing a substrate surface such as a single crystal wafer or glass plate, and the polishing pad produced by the method, and the polishing It relates to a polishing method using a pad.

Recently, the use of gallium nitride-based LEDs are used for high-brightness white LEDs for LCDs, LCD backlight units, signals, and the like, and are used for backlight sources of TFT-LCDs, cell phone backlight sources, and keypads.

In addition, lighting LEDs can significantly improve energy consumption efficiency through power consumption of about 10 to 20%, semi-permanent life of more than 100,000 hours, and environmentally friendly characteristics, compared to conventional lighting fixtures represented by fluorescent and incandescent lamps. Therefore, it is attracting attention as the next generation technology to replace general lighting fixtures.

In the manufacture of such LEDs, an essential material is a sapphire wafer in which a semiconductor epitaxial layer is formed of a gallium nitride compound such as GaN or GaAlN.

However, when performing a workpiece polishing process including a sapphire wafer using a conventional polishing pad, when the polishing slurry supplied to the surface is not fine and contains unevenly large particles, large particles of the polishing slurry are removed. There is a problem in that scratches are generated in a wafer or the like which is collected and requires high-precision polishing.

In addition, when the polishing pad of the prior art is used, the amount of the polishing slurry is used, and the support surface of the work surface is weak, and the life span is short, so the economic efficiency is low. In particular, the high flattening and high roughening processing required for ultra-precision polishing of semiconductor wafers There is a limiting problem in realizing this.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and by constituting a polymer polishing pad containing nanodiamonds, the amount of polishing slurry used in the polishing process is reduced, and structurally sufficient elastic force and work surface support force during polishing work A method of manufacturing a polishing pad comprising nanodiamonds, and a polishing pad manufactured by the method, and the polishing pad, which can be used for a long time and can be used stably for a long time, and can reduce the occurrence of scratches on the polishing surface and enable high-precision polishing. It is an object to provide a polishing method using.

A polishing pad manufacturing method including nanodiamonds according to the present invention for realizing the above object comprises: a mixing process of uniformly dispersing and mixing abrasive particles and nanodiamonds in an appropriate ratio in a polyurethane resin; A molding process of injecting the materials uniformly dispersed and mixed through the mixing process into a mold and molding them into a predetermined shape; A curing step of drying the molded article molded in the molding step in a dryer; A slicing process of manufacturing a polishing pad by thinly cutting a molded product dried by the curing process to a predetermined thickness; A buffing step of smoothing the surface to be polished in the polishing pad manufactured by the slicing process by a method of rotating the buff at a high speed; It characterized in that it comprises a cutting process for cutting to match the size of the polishing pad to be produced after the buffing process.

Between the buffing process and the cutting process may include a taping process for attaching the adhesive member on the back surface of the polishing surface of the polishing pad.

The abrasive particles may be composed of one or more of boron carbide (B ₄ C), cesium trioxide (CeO ₃ ), silicon carbide (SiC), silica (SiO ₂ ) particles are mixed.

When the nanodiamonds are agglomerated in air, it is preferable to have a particle size of 30 to 40 nm.

It is preferable to use the nanodiamond having a high purity of 90% or more.

The amount of the abrasive grains is added in the range of 30 to 50% wt relative to the amount of the polyurethane resin (wt), and the amount of nanodiamonds is added in the range of 0.1 to 5% wt relative to the amount of the abrasive grains (wt). It is desirable to.

More preferably, the amount of the abrasive grains is added in the range of 40-50% wt relative to the amount of the polyurethane resin (wt), and the amount of nanodiamonds is 1-2% of the amount of the abrasive grains (wt). It can be added in the wt range.

Next, the polishing pad comprising the nanodiamond according to the present invention for realizing the above object is characterized in that it is manufactured by the manufacturing method of the polishing pad comprising the nanodiamond as described above.

Next, a polishing method using a polishing pad containing nanodiamonds according to the present invention for realizing the above object is a workpiece polishing method using the polishing pad containing the nanodiamonds, the polishing pad is fixed on a polishing platen. A first step of positioning and fixing the workpiece on the polishing pad; When the workpiece is fixed on the polishing pad in the first step, the polishing platen and the polishing pad are rotated while providing a surface abrasive and a lubricant including nanodiamonds on the polishing pad, thereby rotating the workpiece with the polishing pad and the abrasive. A second step of grinding and processing; When the polishing of the workpiece is finished through the second step, cleaning the workpiece, and then inspecting the polished surface of the workpiece.

The polishing pad manufacturing method including the nanodiamond according to the present invention, the polishing pad manufactured by the method, and the polishing method using the polishing pad have the following effects.

The present invention can significantly reduce the amount of polishing slurry used by using a polymer polishing pad containing nanodiamonds, which are abrasive fine particles, and have a strong support on the working surface so that it can be used for a long time, thereby contributing to economic efficiency. have.

In addition, the present invention has the effect of enabling high-precision polishing while reducing the occurrence of scratches on the polishing surface, thereby contributing to the improvement of polishing quality. That is, the polishing pad according to the present invention can be expected to improve the polishing efficiency during the grinding operation by containing nano-diamond particles of a uniform size, there is an effect that can increase the amount of the polishing pad by increasing the polishing speed.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a schematic view showing a chemical mechanical polishing (CMP) for polishing a workpiece using a polishing pad including nanodiamonds according to the present invention.

Reference numeral 10 denotes a polishing plate, which is rotatably formed, and preferably made of a metal body having a disc structure.

On the upper portion of the polishing plate 10, a polishing pad 15 including nanodiamonds according to the present invention is fixed. The specific configuration of the polishing pad 15 and the like will be described in detail below.

When the workpiece S is fixed on the polishing pad 15, the upper surface 20 made of a ceramic block is lowered to apply the pressure to the workpiece S such as a wafer and the polishing plate 10 and the polishing pad ( The surface of the workpiece S is polished and rotated while rotating 15).

In this case, the polishing slurry P is provided on the polishing pad 15. As the polishing slurry P, a mixed or composite slurry polishing agent P made of nanodiamonds and silica (SiO ₂ ) can be used.

On the other hand, the workpiece S is made of any one or more materials selected from the group consisting of silicon carbide, silicon carbide, gallium nitride, indium gallium nitride, sapphire, quartz, lithium tantalate, lithium borate (borate) and silicon Can be.

Now, a method of manufacturing the polishing pad 15 including the nanodiamonds will be described with reference to FIG. 2.

First, a mixing process of uniformly dispersing and mixing abrasive particles and nanodiamonds in an appropriate ratio in a polyurethane resin is performed. In the mixing process, it is preferable to mix the abrasive particles and the nanodiamond particles together with the polyurethane resin using a mixer or a vacuum degassing machine so that the nanodiamond particles and the abrasive particles can be uniformly dispersed and mixed in the polyurethane resin. .

It is preferable that the mixing ratio of the main body and the curing agent is approximately 2: 1, but the polyurethane resin is not limited thereto and may be appropriately mixed with the curing agent according to the hardness to be carried out.

The abrasive particles are preferably composed of one or more particles of boron carbide (B ₄ C), cesium trioxide (CeO ₃ ), silicon carbide (SiC), silica (SiO ₂ ), and the like. In addition, it is also possible to include the particles of other known components commonly used as abrasive particles, or to constitute alone.

Nanodiamonds generally have the property of electrostatic attraction to easily aggregate. For example, even though the particle size of the nanodiamond particles is 4 nm, the particle size is easily aggregated in the air, and thus the particle size may be aggregated up to 30 to 40 nm. In addition, if physical shaking occurs when the nanodiamonds are stored, the electrostatic attraction between particles and particles is largely acted on, and thus the nanodiamonds may have a condensed shape up to a size of 20 to 50 μm. Such nanodiamonds should be at least 90% high purity, and the high purity crystal measure involves carbon bonding. When there is only a single bond between carbons and no other impurities, it can be considered as high purity.

Therefore, it is preferable that the nanodiamonds used in the present invention have a particle size of 4 to 6 nm and have a particle size of 30 to 40 nm when agglomerated at room temperature (in air) and have a high purity of 90% or more. If the particle size of the nanodiamonds are agglomerated to a size of 40 nm or more, it will adversely affect the polishing quality.

Polishing pad 15 according to the present invention is produced using a polyurethane resin, abrasive particles, nano diamond, the abrasive particles, 30 to 50% wt in the amount compared to the polyurethane resin amount (wt) Preferably, the amount of the abrasive particles is more preferably 40 to 50% wt relative to the polyurethane resin.

The ratio of nanodiamond input (mixed) to the abrasive grains is in the range of 0.1 to 5% wt relative to the amount of abrasive grains (wt), and more preferably, the nanodiamond input amount is about 1 to 2% wt relative to the abrasive grains (wt).

Next, a mold injection process of injecting uniformly dispersed and mixed materials into the mold through the mixing process is performed, and a molding process of molding into a predetermined shape (pattern) is performed. Herein, the molding shape is preferably formed in a shape having a constant size for slicing in a slicing process to be carried out later.

Next, a curing process of drying the molded article molded in the molding process at about 60 to 80 ℃ in a dryer for about 40 to 60 minutes is performed.

Next, the slicing process is performed by slicing the dried molded product thinly to a predetermined thickness through a curing process to produce a polishing pad, and then, the surface to be polished from the polishing pad produced by the slicing process is buffed. A smooth buffing process is performed by highway rotation.

Next, a taping process of attaching an adhesive member such as a double-sided tape to the back surface of the polishing pad of the polishing pad is performed. At this time, by attaching a double-sided tape to the polishing pad, it can also be used directly attached to the polishing surface 10 of the polishing equipment as illustrated in Figure 1, if necessary, a pad having a predetermined thickness attached to the back of the polishing pad In one state, it is also possible to use the polishing pad 15 by attaching the pads on the polishing surface 10 of the polishing equipment.

Next, when the taping process as described above is completed, the polishing pad 15 is manufactured by performing a cutting process of cutting according to the size of the polishing pad to be manufactured.

Of course, it is also possible to omit the taping step, and to perform the cutting step immediately after the buffing step.

The polishing pad 15 according to the present invention manufactured by the above method is formed by polishing particles of SiC, B ₄ C, CeO ₃ , SiO _2, etc., nanodiamond, polyurethane resin components, and then molded to a certain thickness. It consists of a configuration attached to the surface plate (10).

Thus, the functions and roles of the main components constituting the polishing pad 15 according to the present invention are as follows.

Polyurethane resin serves to have a certain shape so that this state can be maintained in a state where the nano diamond and abrasive particles are evenly dispersed. In addition, the polishing pad provides sufficient elastic force and support when the workpiece is polished or ground, thereby increasing polishing efficiency and extending the life of the polishing pad.

When the abrasive grains are formed by mixing only nanodiamond particles to form a polishing pad, the abrasive grains may cause scratches on a wafer requiring high precision polishing, and serve to compensate for a problem that the polishing precision may be degraded. In addition, when the abrasive particles are supplied only in the form of abrasive slurry, when the abrasive slurry supplied to the surface is not fine and contains non-uniformly large particles, the abrasive particles are collected as in the conventional polishing pads, and the scratch Since it hinders the polishing force in the process requiring high precision, it directly configures the polishing pad to solve the polishing imbalance and increase the polishing precision.

In case of using only abrasive particles, nanodiamonds may have poor flatness and roughness due to the delay of the polishing time and the delayed time. Therefore, the nanodiamonds are mixed with the abrasive particles to increase the overall polishing power and to shorten the polishing time. .

The workpiece polishing method using the polishing pad 15 including the nanodiamond according to the present invention as described above will be described.

First, the polishing pad 15 according to the present invention is fixed on the polishing plate 10, and the workpiece S is positioned and fixed on the polishing pad 15.

When the workpiece S is fixed on the polishing pad 15, the polishing plate 10 and the polishing pad are provided on the polishing plate 10 and the polishing pad 15 while providing surface abrasives and lubricants including nanodiamonds. (15) is rotated, and the to-be-processed object S is grind | polished with the said polishing pad 15 and an abrasive | polishing agent, and is processed.

Here, the surface abrasive containing nano diamond, may be composed of colloidal silica (SiO ₂ ) 60 ~ 72wt%, 0.5 ~ 3wt% diamond having a nanoparticle diameter, 27.5 ~ 37 wt% of ethylene glycol (Ethylene glycol) have. In this case, it is preferable to use SiO 2 abrasive grains having an average particle size of 50 to 80 nm in an alkaline solution including potassium hydroxide (KOH) and amine series (NH ₄ OH). And it is preferable to use a nanodiamond whose particle diameter is 10 nm-50 nm.

In this manner, when the polishing of the workpiece S is finished, the workpiece S is washed, and then the polished surface of the workpiece S is inspected.

When the workpiece S is polished using the polishing pad 15 and the surface abrasive including such a nanodiamond, the workpiece has a surface roughness of 3 kPa or less and a flatness of 3 μm or less. Thus, the workpiece S excellent in both surface roughness and flatness characteristics can be manufactured.

In addition, the workpiece polishing method according to the present invention can achieve a result of improving the polishing performance while simplifying the conventional two-step polishing process into one one-step polishing process. That is, conventionally, the workpiece is polished while spraying the microdiamond abrasive in the first step, then cleaned and inspected, and then the workpiece is polished again using the colloidal silica abrasive in the second step, and then cleaned and inspected. Was carried out. However, in the above-described workpiece polishing method of the present invention, after polishing the workpiece S by using the polishing pad 15 and the surface abrasive included in the nanodiamond, the workpiece S is cleaned and inspected. As a result, the polishing performance can be improved while simplifying the process.

Hereinafter, an actual polishing test example using a polishing pad including nanodiamond according to the present invention as described above will be described.

Sapphire wafers and silicon carbide wafers were used as the workpieces of this test example.

In addition, the conditions of the polishing equipment is a polishing rate of 30 ~ 50rpm, the amount of polishing per hour varies depending on the workpiece, it is approximately 2 ~ 4μm.

Flatness (GBIR) analysis after polishing the workpiece was performed by Nidex FT-17, which is a flatness measuring instrument, and surface roughness (RA) measurement was performed by AFM (Atomic Force Microscope).

[Processing Example 1]

Comparing the flatness and surface roughness by polishing the sapphire wafer with the conventional polishing pad described above and polishing with a polishing pad including nanodiamonds, as shown in Table 1 and FIGS. 3A to 4B, respectively.

TABLE 1

Conventional Polishing Method Polishing method of the present invention flatness
(Flatness) 1.25 μm 1.00 μm Surface roughness
(Surface Roughness) 1.08Å 0.93Å

Figure 3a is a view showing the flatness (flatness 1.25㎛) of the sapphire wafer processed using a conventional polishing pad, Figure 3b is a flatness (flatness 1.00 of the sapphire wafer processed using a polishing pad according to the present invention) Μm).

Figure 4a is a view showing the surface roughness (Ra 1.08Å) of the sapphire wafer processed using a conventional polishing pad, Figure 4b is a surface roughness (Ra 0.93Å) of a sapphire wafer processed using a polishing pad according to the present invention Figure showing.

As described above, as shown in Table 1 and FIGS. 3A, 3B, and 4A, 4B, the surface of the polishing pad including nanodiamond according to the present invention is reduced in flatness and surface roughness than the conventional polishing pad. It can be seen that the processing state is improved.

[Processing Example 2]

Comparing the flatness and the surface roughness by polishing the silicon carbide wafer with a conventional polishing pad and polishing with a polishing pad containing nanodiamonds, as shown in Table 2 and Figures 5a to 6b below.

TABLE 2

Conventional Polishing Method Polishing method of the present invention flatness
(Flatness) 1.70 μm 1.60 μm Surface roughness
(Surface Roughness) 1.25Å 1.01Å

Figure 5a is a view showing the flatness (flatness 1.70㎛) of a silicon carbide wafer processed using a conventional polishing pad, Figure 5b is a flatness (flatness) of a silicon carbide wafer processed using a polishing pad according to the present invention 1.60 μm).

6A illustrates a surface roughness (Ra 1.25 1.) of a silicon carbide wafer processed using a conventional polishing pad, and FIG. 6B illustrates a surface roughness (Ra 1.01) of a silicon carbide wafer processed using a polishing pad according to the present invention. Iii) is a diagram showing.

In the experimental results of the silicon carbide wafer as described above, as shown in Table 2 and FIGS. 5A and 5B and 6A and 6B, the polishing pad including nanodiamond according to the present invention has a flatness and surface roughness than that of the conventional polishing pad. It can be seen that the numerical value is reduced to improve the surface finish.

1 is a schematic diagram showing a polishing apparatus for polishing a workpiece using a polishing pad according to the present invention.

2 is a flowchart illustrating a method of manufacturing a polishing pad including nanodiamonds according to the present invention.

Figure 3a is a view showing the flatness of the sapphire wafer processed using a conventional polishing pad,

Figure 3b is a view showing the flatness of the sapphire wafer processed using the polishing pad according to the present invention.

Figure 4a is a view showing the surface roughness of the sapphire wafer processed using a conventional polishing pad,

Figure 4b is a view showing the surface roughness of the sapphire wafer processed using the polishing pad according to the present invention.

5A is a view showing the flatness of a silicon carbide wafer processed using a conventional polishing pad,

5B is a view showing the flatness of the silicon carbide wafer processed using the polishing pad according to the present invention.

6a is a view showing the surface roughness of a silicon carbide wafer processed using a conventional polishing pad,

6b is a view showing the surface roughness of the silicon carbide wafer processed using the polishing pad according to the present invention.

Claims (9)

A mixing process of uniformly dispersing and mixing the abrasive particles and the nanodiamonds in an appropriate ratio in a polyurethane resin; A molding process of injecting the materials uniformly dispersed and mixed through the mixing process into a mold and molding them into a predetermined shape; A curing step of drying the molded article molded in the molding step in a dryer; A slicing process of manufacturing a polishing pad by thinly cutting a molded product dried by the curing process to a predetermined thickness; A buffing step of smoothing the surface to be polished in the polishing pad manufactured by the slicing process by a method of rotating the buff at a high speed; After the buffing process polishing pad manufacturing method comprising a nano-diamond comprising a cutting process for cutting to match the size of the polishing pad to be produced. The method according to claim 1, Between the buffing process and the cutting process polishing pad manufacturing method comprising a nano-diamond comprising a taping process for attaching the adhesive member on the back surface of the polishing surface of the polishing pad. The method according to claim 1, The abrasive grains include abrasives comprising nanodiamonds, characterized in that boron carbide (B ₄ C), cesium trioxide (CeO ₃ ), silicon carbide (SiC), silica (SiO ₂ ) particles are formed by mixing one or more of them. Pad manufacturing method. The method according to claim 1, The nano-diamond is a polishing pad manufacturing method comprising a nano-diamond, characterized in that having a particle size of 30 ~ 40nm when aggregated in the air. The method according to claim 1, The nano diamond is a polishing pad manufacturing method comprising a nano diamond, characterized in that using a high purity of 90% or more. The method according to claim 1, The amount of the abrasive grains is added in the range of 30 to 50% wt relative to the amount of the polyurethane resin (wt), and the amount of nanodiamonds is added in the range of 0.1 to 5% wt relative to the amount of the abrasive grains (wt). Polishing pad manufacturing method comprising a nano-diamond characterized in that. The method according to claim 1, The amount of the abrasive grains is added in the range of 40-50% wt relative to the amount of the polyurethane resin (wt), and the amount of nanodiamonds is in the range of 1-2% wt relative to the amount of the abrasive grains (wt). Polishing pad manufacturing method comprising a nano-diamond characterized in that. The polishing pad containing nanodiamond manufactured by the manufacturing method of the polishing pad containing the nanodiamond in any one of Claims 1-7. A workpiece polishing method using a polishing pad containing nanodiamonds according to claim 8, A first step of fixing the polishing pad on a polishing plate and positioning and fixing a workpiece on the polishing pad; When the workpiece is fixed on the polishing pad in the first step, the polishing platen and the polishing pad are rotated while providing a surface abrasive and a lubricant including nanodiamonds on the polishing pad, thereby rotating the workpiece with the polishing pad and the abrasive. A second step of grinding and processing; When the polishing of the workpiece is finished through the second step, cleaning the workpiece, and then inspecting the polished surface of the workpiece.

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