KR20090020725A

KR20090020725A - Polishing pad and method of manufacturing the same

Info

Publication number: KR20090020725A
Application number: KR1020070085236A
Authority: KR
Inventors: 원 준 김; 영 남 황
Original assignee: 주식회사 코오롱
Priority date: 2007-08-24
Filing date: 2007-08-24
Publication date: 2009-02-27

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 method for manufacturing the same. And the surface of the microfiber is arranged at an orientation angle θ of 0 to 30 ° with respect to the longitudinal direction of the polishing pad.

In the present invention, the orientation angle (θ) of the microfine fibers arranged on the surface is small, so that the surface is uniform and pores are formed between the microfine fibers, so that the polishing performance is excellent without the process of forming the pores separately, and scratches during polishing Low incidence

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.

2 is a schematic view of the surface 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

F: Ultrafine fibers arranged on the surface of the polishing pad

X: longitudinal axis of polishing pad Y: longitudinal axis of microfiber

θ: angle of orientation of microfibers

A: Nonwoven Fabric Impregnated with Polymer Elastomer

B: polymer elastomer layer

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.

As another conventional polishing pad, Japanese Patent Laid-Open No. 9-59395 proposes a polishing pad in which a polyurethane resin is impregnated into a nonwoven fabric composed of about 1 to 5 denier synthetic short fibers. However, the conventional polishing pad has a high modulus value because of the high single yarn fineness of the synthetic short fibers constituting the nonwoven fabric, so that the synthetic short fibers arranged on the surface of the polishing pad form the longitudinal direction of the polishing pad, that is, the orientation angle θ. Is as large as 30 ~ 50 °.

Therefore, the conventional polishing pad has a problem in that the surface becomes uneven and the short fibers arranged on the surface are thick so that there is a lack of voids formed therebetween, resulting in a decrease in polishing performance.

In order to solve the above problems, the present invention is dispersed in the sea component (S) which is an alkali-soluble copolyester and the sea component (S), and has a single yarn fineness of 10 to 1000 island components having 0.001 to 0.3 denier. The nonwoven fabric is made of an island-in-the-sea composite fiber composed of (I) to provide a polishing pad in which microfibers are uniformly arranged at a low orientation angle θ 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 interwoven with microfibers having a fineness of 0.001 to 0.3 denier and a polymer elastic body impregnated in the nonwoven fabric, and the surface of the microfiber is 0 to the longitudinal direction of the polishing pad. It is characterized by arrange | positioning at the orientation angle (theta) of 30 degrees.

Figure 2 is a schematic diagram of the surface of the polishing pad according to the present invention shows the meaning of the orientation angle (θ).

The orientation angle θ means an angle θ formed between the longitudinal axis Y of the ultrafine fibers arranged on the surface of the polishing pad and the longitudinal axis X of the polishing pad.

The smaller the orientation angle θ, the more uniformly the fibers are arranged on the surface.

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.

The ultrafine fibers are preferably polyamide fibers in consideration of affinity with polyamide fibers, polyester fibers, and the polishing liquid.

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 ultrafine fiber strength and the strength of the polishing cloth are lowered. If the single yarn fineness is more than 0.3 denier, the fibers are arranged at an excessively large orientation angle (θ) on the surface of the polishing pad, resulting in uneven surface and porosity. It does not form well and polishing uniformity falls.

In addition, the surface of the polishing pad of the present invention has some of the microfibers in the hair.

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, the nonwoven fabric is impregnated with a polymer elastomer, and then treated with an aqueous alkali solution to elute the sea component (S), and then buffed to prepare microfibers on the surface to prepare a polishing pad.

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 which is the above-mentioned sea component has polyethylene terephthalate as a main component, and as an additional component, molecular weight 400-20000, most preferably 1000-4000 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.

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.

It is preferable that the weight ratio of the fiber base material which consists of a polymer elastic body / microfine fiber is 30/70-90/10.

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 a microfine fiber having a single yarn fineness of 0.001 to 0.3 denier After preparing to impregnate the high-strength polymer elastomer thereon and brushed to prepare a polishing pad.

As a result, the process of forming a separate polyurethane coating layer (B) can be omitted, which simplifies the manufacturing process and makes the surface uniform by arranging the microfibers on the surface of the polishing pad at an orientation angle (θ) of 30 ° or less. As a result, it is easy to uniformly adjust fine pores.

In the present invention, the method for measuring the orientation angle θ of the ultrafine fibers arranged on the surface of the polishing pad is as follows.

After scanning electron micrograph of the longitudinal side surface of the polishing pad, the original image is taken and more than 10 fibers are collected in the longitudinal direction using i-Soution software, an image analysis program of IMT Technology, in Korea. Measure the angle of and set the average value to the orientation angle (θ) of the ultrafine fibers.

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 with a three-dimensional profile while scanning the surface area range (100 μm × 1000 μm) of the polished silicon wafer 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 Incidence (%)

The number of scratches that scratch defects occur when polishing 100 square inches of silicon wafer with a polishing pad is calculated 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 One

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 also cut to 50 mm in length, short fibers, carded and cross-wrapper process to produce a laminated web of the island-in-the-sea composite short fibers, then needle punched to produce a non-woven fabric of island-in-the-sea composite fibers 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 then brushed with a brush to form microfiber hairs on the surface to prepare a polishing pad.

The orientation angle θ of the ultrafine fibers arranged on the surface of the prepared polishing pad was 20 °.

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.

The orientation angle θ of the ultrafine fibers arranged on the surface of the prepared polishing pad was 23 °.

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 single densities of 3 deniers were manufactured through a carding and cross-wrapping process to produce laminated webs thereof, and then needle punched to prepare nonwoven fabrics.

Next, the prepared nonwoven fabric was impregnated with 40% by weight of the polyurethane resin relative to the nonwoven fabric, and then wet coagulated to prepare a polishing pad.

The orientation angle θ of the fibers arranged on the surface of the prepared polishing pad was 45 °.

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 14.40 14.54 13.98 Scratch Rate (%) 0.11 0.12 0.18

In Examples 1 and 2, microfibers on the surface were arranged at an orientation angle (θ) smaller than that of Comparative Example 1, and scratch rate and polishing performance (surface average roughness of the polished wafer) were better than Comparative Example 1.

According to the present invention, the orientation angle (θ) of the microfine fibers arranged on the surface is smaller than that of the conventional polishing pad, so that the surface is uniform and the pores are formed between the microfine fibers so that the polishing performance is not required. It is excellent and has low scratch rate during polishing.

Claims

Microfibers with 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 on the surface of the microfine fibers at an orientation angle (θ) of 0 to 30 ° with respect to the longitudinal direction of the polishing pad. Polishing pads, characterized in that arranged.

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

The polishing pad according to claim 1, wherein the ultrafine fibers are made of polyamide 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, impregnating the polymer elastic body in the nonwoven fabric and then treating it with an aqueous alkali solution to elute the sea component (S), and then buffing it to form a microfiber on the surface of the polishing pad manufacturing method characterized in that .

The method for manufacturing a polishing pad according to claim 4, 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.