KR101009610B1 - Polishing pad and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a polishing pad used in a CMP process such as a silicon wafer, a plate glass for display, a nonwoven fabric in which an island-in-the-sea composite fiber (F ₁ ) and an alkali-soluble co-polyester fiber (F ₂ ) are mixed. After impregnating the polymer elastic body to the treated with an aqueous alkali solution to prepare a polishing pad.

The present invention has the advantage of a simple process for forming a pore (Pore) in the polishing pad, the presence of ultrafine fibers on the surface, low scratch rate during polishing, and excellent polishing efficiency.

In addition, the present invention can form a large number of voids in the polishing pad whose angle (θ) formed by the longitudinal direction (y) of the voids and the longitudinal direction (x) of the polishing pad is 5 ° or more.

Polishing, Pads, CMP, Wafers, Air gaps, Sea island

Description

Polishing pad and method of manufacturing the same

1 is a cross-sectional view of the island-in-the-sea composite fiber used for manufacturing the polishing pad of the present invention.

Figure 2 is a schematic cross-sectional view of the polishing pad according to the present invention.

Figure 3 is a schematic cross-sectional view of a conventional polishing pad.

* Code description for main parts of the drawings

S: Sea component I: Island component

A: Pad impregnated with a polymer elastomer in a nonwoven fabric composed of ultrafine fibers

B: coating layer of polymer elastomer

R: Polishing Pad

P: Pore

x: Polishing pad longitudinal axis

y: void longitudinal axis

θ: the angle between x and y

The present invention is useful for chemical mechanical polishing (CMP), particularly for CMP methods of planarizing flat glass or other substrates for silicon wafers or displays used in the manufacture of integrated circuit chips or the like. A polishing pad and a method of manufacturing the same.

The silicon wafer and the like are smoothly processed by the CMP polishing apparatus, and the CMP polishing apparatus includes a lower board having a circular rotating plate on which the polishing pad is mounted, an upper board which adheres the silicon wafer to the polishing pad, and a device for supplying slurry to the polishing pad. do.

Chemical-mechanical polishing, a CMP operation, pushes the surface of the semiconductor wafer on which the integrated circuit will be fabricated in the opposite direction to remove oxides, including deposited Si-based oxides, and creates a very smooth and flat surface on the wafer. As an operation, deionized water and / or chemically active reagents are applied along with the polishing liquid to the interface between the wafer and the polishing pad during the CMP operation.

As a polishing pad used in a conventional CMP method, Japanese Laid-Open Patent Publication No. 2005-329491 discloses a pad impregnated with a polyurethane resin, which is a polymer elastomer in a nonwoven fabric composed of nylon short fibers of about 1 to 5 denier as shown in FIG. ), A polishing pad having a structure in which the coating layer (B) of the polymer elastomer is formed.

However, the conventional polishing pad is manufactured by manufacturing the pad (A) by impregnating a polyurethane resin in a nonwoven fabric and then coating the polyurethane resin on it to form a coating layer, which is very complicated. There was a problem that it is difficult to uniformly control the size of the pores formed in the polymer elastomer coating layer B.

In addition, the conventional polishing pad has a short service life and a serious waste of materials since it cannot be used even if the pad A positioned below the wear is not worn at all when the polymer elastomer coating layer (B) having voids is worn out. there was.

The present invention is to solve the conventional problems as described above, instead of forming a separate polymer elastomer layer (B) on the pad (A) impregnated with a polymer elastomer in the nonwoven fabric and the island-like composite fibers (F ₁ ) Impregnating the polymer elastomer in the nonwoven fabric containing the alkali-soluble co-polyester fiber (F ₂ ) and then treating it with an aqueous alkali solution to remove the sea component (S) in the island-in-the-sea composite fiber and the alkali-soluble co-polyester fiber in the nonwoven fabric ( It is intended to provide a method for producing a polishing pad in which fine pores are formed by eluting F ₂ ), and a polishing pad manufactured therefrom.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, the manufacturing method of the polishing pad according to the present invention is an island-in-the-sea composite fiber composed of sea component (S) which is an alkali-soluble polyester and island component (I) having a single yarn fineness of 0.001 to 0.3 denier as shown in FIG. (F ₁ ) A nonwoven fabric containing 20 to 80% by weight and 80 to 20% by weight of an alkali-soluble co-polyester fiber (F ₂ ) having a single yarn fineness of 5 to 10 deniers was prepared. After impregnation, it is treated with an aqueous alkali solution to elute the sea component (S) and the alkali-soluble co-polyester fiber (F ₂ ) in the island-in-the-sea composite fiber (F ₁ ).

1 is a cross-sectional view of an island-in-the-sea composite fiber used for manufacturing a polishing pad according to the present invention.

First, as shown in FIG. 1, the island-in-the-sea composite fiber (F ₁ ) 20 to 80 made of sea component (S), which is an alkali-soluble polyester, and island component (I) having a single yarn fineness of 0.001 to 0.3 denier. A nonwoven fabric is prepared in which 80 to 20% by weight of alkali-soluble co-polyester fiber (F ₂ ) having 5% by weight and single yarn fineness is mixed.

Typically, the weight ratio of sea component (S) to island component (I) in island-in-the-sea composite fiber (F ₁ ) is 7: 3 to 5: 5.
When the weight ratio of the island-in-the-sea composite fiber (F ₁ ) and the alkali-soluble co-polyester fiber (F ₂ ) is out of the above range, the content of the ultrafine fibers in the polishing pad is too low to increase the scratch occurrence rate during polishing, or Pore is formed in too small a problem that the polishing performance is poor.

The total fineness of the island-in-the-sea composite fiber (F ₁ ) is preferably 2 to 4 denier.

Next, the polymer is impregnated into the nonwoven fabric and then treated with an aqueous alkali solution to elute and polish the sea component (S) and the alkali-soluble co-polyester fiber (F ₂ ) in the island-in-the-sea composite fiber (F ₁ ). Prepare the pads.

Alkali-soluble copolyester as the sea component has polyethylene terephthalate as a main component, and is an additional component with a molecular weight of 400 to 20000, most preferably 1000 to 4000 polyethylene glycol, polypropylene glycol, 1,4-cyclohexanedicar Acids, 1,4-cyclohexanedimethanol, 1,4-cyclohexanedicarboxylate, 2,2-dimethyl-1,3-propanediol, 2,2-dimethyl-1,4-butanediol, 2, 2,4-trimethyl 1,3-propanediol and copolyester obtained by copolymerizing 25% by weight or less of one or two or more selected from adipic acid.

Moreover, it is preferable that a island component is a polyester resin or a polyamide resin.

Polyurethane resins, polyurea resins, polyacrylic acid resins, and the like may be used as the polymer elastomer, but polyurethane resins are preferable in terms of processed tablets, abrasion resistance, and hydrolysis resistance.

The weight ratio of the fibrous base composed of the polymer elastomer / microfiber is preferably 30/70 to 90/10.

If the weight ratio of the polymer elastomer is less than 30% by weight, the hardness of the polishing pad is too low, and if it exceeds 90% by weight, the hardness of the polishing pad may be too high.

The method of filling a polymer elastomer may impregnate and / or apply an organic solvent solution or an aqueous dispersion of the polymer elastomer to a nonwoven fabric and then attach it by wet coagulation or dry coagulation.However, the polymer elastomer may form voids between fiber bundles in a nonwoven fabric. It is necessary to attach it uniformly in a substantially filling form, and solidifying the polymer elastomer in a porous shape is preferable for polishing without causing defects such as scratching due to slurry agglomeration or polishing residues. After filling the polymer elastomer by the wet coagulation method, the method of increasing the density of the polymer elastomer by the second dry coagulation method is most suitable.

As an organic solvent of a high molecular elastic body, toluene, acetone, methyl ethyl ketone, etc. other than polar solvents, such as dimethylformamide, dimethylacetamide, and dimethyl sulfoxide, can be used.

The polishing pad of the present invention manufactured by the above method is composed of a nonwoven fabric in which microfibers having a fineness of 0.001 to 0.3 deniers intersect with each other and a polymer elastic body impregnated in the nonwoven fabric, so that micropores are formed on both sides and the inside thereof. have.

Single yarn fineness of the ultrafine fibers is 0.001 ~ 0.3 denier.

If the single yarn fineness is less than 0.001 denier, the fine fiber strength and the strength of the polishing cloth are lowered. If the single yarn fineness is greater than 0.3 denier, the polishing uniformity is lowered. Becomes lower.

The microfiber is composed of polyester resin, polyamide resin and the like, but is composed of polyamide resin is advantageous for improving affinity with the polishing liquid.

In the present invention, instead of forming a polyurethane coating layer (B) having a separate void on the pad (A) impregnated with a polyurethane resin on a conventional nonwoven fabric, the nonwoven fabric is an island-in-the-sea composite fiber (F ₁ ) and an alkali It is prepared by using the water-soluble copolymer polyester fiber (F ₂ ) and then impregnated with a polymer elastic body and then treated with an aqueous alkali solution to the sea component (S) in the nonwoven fabric and the alkali-soluble copolymer copolymer polyester fiber (F ₂ ) Elution to prepare a polishing pad.

Therefore, the process of forming a separate polyurethane coating layer (B) can be omitted, which simplifies the manufacturing process and makes it easy to uniformly adjust the pore site formed in the polishing pad.

In addition, in the present invention, since voids of a predetermined size are formed over the entire thickness of the polishing pad, the surface of the polishing pad can be used continuously even if the surface is worn by the polishing process, thereby increasing its service life.

In addition, since the single yarn fineness of the alkali-soluble co-polyester fiber (F ₂ ) is greater than that of the island-in-the-sea composite fiber (F ₁ ), the modulus of the water-soluble co-polyester fiber (F ₂ ) is an island-in-the-sea composite fiber (F ₁ ). Greater than the modulus of F ₁ ).

Thus, in the polishing pad, the alkali-soluble copolyester fiber (F ₂ ) is arranged at an angle closer to the vertical direction with respect to the longitudinal direction (x) of the polishing pad than the island-in-the-sea composite fiber (F ₁ ), and the aqueous alkali solution. As the fiber F ₂ is eluted by the treatment, as shown in FIG. 2, a plurality of voids having an angle θ of at least 5 ° formed by the longitudinal axis y of the void with the longitudinal axis x of the polishing pad are formed in the polishing pad. do.
As described above, since the alkali-soluble copolyester fiber (F ₂ ) has a larger modulus than the island-in-the-sea composite fiber (F ₁ ), that is, because the fiber hardness is high, the alkali-soluble co-polyester fiber (F ₂ ) When the non-woven fabric for polishing pad is interwoven with the island-in-the-sea composite fiber (F ₁ ), alkali-soluble co-polyester fibers (F ₂ ) having high fiber hardness are directed in a direction more perpendicular to the longitudinal direction (x) of the polishing pad. It is arranged naturally.
In addition, when the angle between the longitudinal axis x of the polishing pad and the longitudinal axis y of the void is less than 5 °, the voids are in a state lying in the longitudinal direction of the polishing pad, and thus the inherent characteristics of the voids retaining the polishing slurry are present. You can't really play a role.

In the present invention, the surface roughness and scratch occurrence rate of the polished silicon wafer were evaluated as follows.

Surface Average Roughness of Silicon Wafers

Measured using Carl Zeiss' product LSM 5 PASCAL, a type of confocal laser scanning microscope (LSM) facility, and a software package that is a topography for LSM. do.

Specifically, the surface average roughness of the polished silicon wafer is expressed by expressing the irregularities formed on the surface in a three-dimensional profile while scanning the surface area range of the polished silicon wafer (width 1,000 μm × length 1,000 μm) with a laser. Obtain

More specifically, surface average roughness Sa is calculated | required by applying the arithmetic mean of 10 measured values based on JISB0601.

Scratch Rate (%)

When the silicon wafer is polished to 100 square inches by polishing pad, the number of scratches that are caused by scratch defects is identified and substituted into the following equation.

Scratch Rate (%) = (Scratch Count / 100 Sq Inch) x 100

However, if the number of scratches exceeds 100, leave it at 100.

The scratch reading is judged by visual judgment by a skilled expert, and in the case of a faint defect that is difficult to read whether it is scratched with the naked eye, it may rely on the additional measurement of an optical microscope equipped with dark field illumination and image analysis software.

In addition, the scratch judges the scratch that the ratio of the length in the longitudinal direction and the width direction to be 10 to 1 or more.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

However, the present invention is not particularly limited by the following examples.

Example 1

As shown in FIG. 1, island-in-the-sea composite fiber composed of sea component (S) of alkali-soluble copolyester and 300 island component (L) of polyester resin dispersedly arranged in the sea component (S) Single yarn fineness: 0.05 denier) 70% by weight of short fiber (F ₁ ) cut into 50 mm length and 30% by weight of alkali-soluble copolyester short fiber (F ₂ ) of 50 mm in length, carding and cross wrapper After manufacturing the laminated web through the process, needle punching it to produce a nonwoven fabric.

Next, the prepared nonwoven fabric was impregnated with 40% by weight of the polyurethane resin relative to the nonwoven fabric, followed by wet coagulation. Ester fiber (F ₂ ) was eluted to prepare a polishing pad.

100 square inches of the silicon wafer was polished under the following conditions using the prepared polishing pad.

Polishing condition

-Polishing machine: GNP Technology's Poli-500 Polisher

-Polishing time: 10 minutes

Down force: 250g / cm2 (3.5psi) on the wafer surface

-Polishing Table Speed: 120rpm

Wafer Carrier Speed: 120rpm

Slurry flow rate: 700 ml / min

-Slurry type: Nalco 2731, silica slurry diluted with DIW and slurry at 15: 1

Table 1 shows the results of measuring surface average roughness and scratch rate of the polished (polished) silicon wafer.

Example 2

Process and conditions similar to those of Example 1, except that the weight of the island-in-the-sea composite fiber (F1) and the alkali-soluble co-polyester fiber (F ₂ ) was changed to 60% by weight and 40% by weight, respectively, in the production of the nonwoven fabric. A polishing pad was prepared, and 100 square inches of the silicon wafer was polished using the same polishing process as in Example 1.

Table 1 shows the results of measuring the surface average roughness and scratch rate of the polished silicon wafer.

Comparative Example  One

Polyamide short fibers having a single yarn fineness of 3 denier were manufactured by laminating their webs through a carding and cross wrapper process and then needle punching them to prepare a nonwoven fabric.

Next, the pad (A) impregnated with a polyurethane resin in the nonwoven fabric was first prepared by impregnating 40 wt% of the nonwoven fabric with a polyurethane resin, followed by wet coagulation.

Next, by coating a polyurethane resin on the pad (A) to form a coating layer (B) to prepare a polishing pad having a cross section as shown in FIG.

100 square inches of the silicon wafer was polished under the same polishing conditions as in Example 1 using the prepared polishing pad.

Table 1 shows the results of measuring the surface average roughness and scratch rate of the polished (polished) silicon wafer as described above.

Measurement results of polished wafer properties division Example 1 Example 2 Comparative Example 1 Surface Average Roughness of Polished Wafers 13.86 13.89 14.40 Scratch Rate (%) 0.11 0.10 0.17

In Examples 1 and 2, microfibers were arranged on the surface, and scratch rate and polishing performance (surface average roughness of the polished wafer) were better than those of Comparative Example 1.

In addition, in Example 1 and Example 2, the manufacturing process of the polishing pad was simplified compared with Comparative Example 1.

The present invention has the advantage of a simple process for forming a pore (Pore) in the polishing pad, the presence of ultrafine fibers on the surface, low scratch rate during polishing, and excellent polishing efficiency.

In addition, the present invention can form a large number of voids in the polishing pad whose angle (θ) formed by the longitudinal direction (y) of the voids and the longitudinal direction (x) of the polishing pad is 5 ° or more.

Claims (5)

Alkali-soluble polyester (F ₁ ) consisting of sea component (S) which is an alkali-soluble polyester and island component (I) having a single yarn fineness of 0.001 to 0.3 denier, and an alkali having a single yarn fineness of 5 to 10 denier A nonwoven fabric containing 80 to 20% by weight of a water-soluble copolymerized polyester fiber (F ₂ ) is prepared, and then impregnated with a polymer elastomer in the nonwoven fabric, and then treated with an aqueous alkali solution to form the island-in-the-sea composite fiber (F ₁ ). A method for producing a polishing pad, wherein the sea component (S) and the alkali-soluble copolyester fiber (F ₂ ) are eluted. The method of manufacturing a polishing pad according to claim 1, wherein a polymer elastic body is impregnated so that the fibers (F ₁ , F ₂ ) constituting the nonwoven fabric do not blow out to the surface of the nonwoven fabric. The method for producing a polishing pad according to claim 1, wherein the island component (I) is one selected from polyester resins and polyamide resins. The method of manufacturing a polishing pad according to claim 1, wherein the island-in-the-sea composite fiber (F ₁ ) has a total fineness of 2 to 4 deniers. The microfibers produced by the method of claim 1 and composed of microfibers having a fineness of 0.001 to 0.3 denier are composed of a nonwoven fabric impregnated with each other and a polymer elastic body impregnated in the nonwoven fabric, so that pores are formed on both sides and the inside thereof. Polishing pad.

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