KR20090020199A

KR20090020199A - Polishing pad and method of manufacturing the same

Info

Publication number: KR20090020199A
Application number: KR1020070084748A
Authority: KR
Inventors: 원 준 김; 영 남 황
Original assignee: 주식회사 코오롱
Priority date: 2007-08-23
Filing date: 2007-08-23
Publication date: 2009-02-26

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing pad used in a CMP process such as a silicon wafer, a plate glass for display, and a manufacturing method thereof. The present invention relates to a nonwoven fabric in which microfibers having a fineness of 0.001 to 0.3 denier are entangled with each other and a polymer elastic body impregnated with the nonwoven fabric. It is composed, the surface is characterized in that the ultrafine fibers are in the hair of an average length of 2 mm or less.

According to the present invention, pores are formed between microfibers and microfibers, and microfibers and polymer elastomers have excellent polishing performance, manufacturing process is simple, and microfiber yarns are present on the surface, so that the occurrence rate of scratches during polishing is low, and the service life is extended. It has the advantage of being.

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

1: microfibers on the surface of the polishing pad

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

B: coating layer of polymer elastomer

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 solves the conventional problems as described above, it is possible to omit the step of forming a separate polymer elastomer layer (B) to simplify the manufacturing process, the pores (Pore) between microfiber and / or polymer elastomers Is formed to have excellent polishing performance, and to provide a polishing pad to minimize the occurrence of scratches when the microfiber is arranged on the surface.

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

First, the polishing pad according to the present invention is composed of a nonwoven fabric in which microfibers having a fineness of 0.001 to 0.3 denier are entangled with each other, and a polymer elastic body impregnated in the nonwoven fabric, as shown in FIG. It is characterized by having the hair in the following average length.

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

Polyurethane resin, polyurea resin and the like may be used as the polymer elastomer, but a polyurethane resin is most preferable in view of processability.

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

In addition, the surface of the polishing pad according to the present invention has some of the microfine fibers in the average length of 2mm or less, and when the average length of the ultrafine fibers is 2mm or more, the fluidity of the polishing liquid during polishing It worsens and polishing efficiency falls.

Next, a method of manufacturing the polishing pad according to the present invention will be described in detail.

First, in the present invention, as shown in FIG. 1, 10 to 1000 island components (I) dispersed in the sea component (S) which is an alkali-soluble copolyester and the sea component (S) have a single yarn fineness of 0.001 to 0.3 denier (I). Non-woven fabric is made of island-in-the-sea composite fiber consisting of

Next, after impregnating the polymer elastic body in the nonwoven fabric and treating it with an aqueous alkali solution to elute the sea component (S) and then buffing it into the fine fibers having an average length of 2mm or less on the surface of the cross section as shown in FIG. A polishing pad having a schematic diagram is prepared.

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

On the other hand, in the present invention, the nonwoven fabric prepared as described above may be first treated with an aqueous alkali solution to elute the sea component (S), and then impregnated with a polymer elastic body to prepare a polishing pad.

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 the polymer elastomer may impregnate and / or apply an organic solvent solution or an aqueous dispersion of the polymer elastomer to the nonwoven fabric and then attach it by wet coagulation or dry coagulation. 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.

In the polishing pad of the present invention, the surface of the polishing surface is napped.

Adherence of the surface of a grinding | polishing surface can be performed by a method known per se.

What is necessary is just to raise the pad A obtained by filling a nonwoven fabric with a polymeric elastic body, for example in order to obtain the polishing pad with the surface adhered. At this time, it is preferable to increase the raising effect of the fiber by treating the pad (A) with an organosilicon compound. This organosilicon compound should just be generally used in order to improve the activity of a fiber in the fiber treatment of a fiber bubble normally.

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 made of ultrafine fibers and then a polymer elastomer After impregnating and brushing to prepare a polishing pad in which ultrafine fibers with an average length of 2 mm or less are embedded on the surface.

As a result, the process of forming a separate polyurethane coating layer (B) can be omitted, thereby simplifying the manufacturing process and effectively preventing the surface of the wafer being polished from being damaged when the microfiber is arranged on the surface of the polishing pad.

The voids formed between the microfibers and the microfibers serve as a polishing layer pattern.

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 the present invention, the surface roughness and scratch incidence 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 (%)

The number of scratches generated when scratching a silicon wafer with 100 square inch area by polishing pad 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) is cut into 50 mm in length, short fiberized, and the laminated web of the island-in-the-sea composite short fiber is manufactured by carding and cross-wrapper process, and then needle punched to produce a nonwoven fabric of the island-in-the-sea composite fiber. Prepared.

Next, the prepared nonwoven fabric was impregnated with 40% by weight of the polyurethane resin relative to the nonwoven fabric, and then wet coagulated, and then eluted with seawater (S) in an island-in-sea composite fiber by treating with an aqueous alkali solution (caustic soda solution). The brush was manufactured by brushing with a brush to form microfiber hairs having an average length of 1.5 mm on the surface.

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

The nonwoven fabric prepared in Example 1 was first treated with an aqueous alkali solution to elute the sea component (S) in the island-in-the-sea composite fiber, and then, except that the polyurethane resin was impregnated with 40% by weight of the nonwoven fabric and wet-coagulated. A polishing pad was manufactured by the same process and method as in Example 1, 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

Instead of the island-in-the-sea composite fiber used in Example 1, polyamide short fibers having a single denier fineness of 3 denier were manufactured through a carding and cross-wrapper process to manufacture their laminated webs, and then needle punched 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 13.88 13.89 14.32 Scratch Rate (%) 0.11 0.10 0.15

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.

According to the present invention, pores are formed between microfibers and microfibers and between microfibers and a polymer elastic body, so that the polishing performance is excellent and the manufacturing process is simple. In addition, the service life is extended.

Claims

Microfibers having a fineness of 0.001 to 0.3 denier are composed of a nonwoven fabric interwoven with each other and a polymer elastic body impregnated with the nonwoven fabric, and the surface is ground with the microfibers having an average length of 2 mm or less. pad.

The polishing pad of claim 1, wherein the polymer elastomer is one selected from a polyurethane resin and a polyurea resin.

The nonwoven fabric is made of a sea-island composite fiber composed of 10 to 1000 island components (I) having a single yarn fineness of 0.001 to 0.3 denier, dispersed in the sea component (S) which is an alkali-soluble copolyester and the sea component (S). Then, the polymer is impregnated with the nonwoven fabric and then treated with an aqueous alkali solution to elute the sea component (S), and then buffed to form the hair of the ultrafine fibers having an average length of 2 mm or less on the surface. Method for producing a polishing pad.

The method for manufacturing a polishing pad according to claim 3, wherein the prepared nonwoven fabric is first treated with an aqueous alkali solution to elute the sea component (S), and then the polymer elastic body is impregnated therein.