KR101863801B1 - Method for preparing porous polyurethane polishing pad - Google Patents

Abstract

The present invention relates to a method of manufacturing a porous polyurethane polishing pad for use in a chemical mechanical planarization (CMP) process of semiconductors, wherein the porous polyurethane polishing pad produced according to the manufacturing method of the embodiment comprises a large pore ) And a small pore (fine pores), thereby increasing the polishing efficiency through the fine pores and increasing the flow rate of the slurry through the mesopores, thereby enhancing the overall polishing efficiency.

Description

METHOD FOR PREPARING POROUS POLYURETHANE POLISHING PAD [0002]

Embodiments relate to a method of making a porous polyurethane polishing pad for use in a chemical mechanical planarization (CMP) process of semiconductors.

A chemical mechanical planarization (CMP) process during a semiconductor manufacturing process is a process in which a wafer is chemically treated by supplying a slurry, with the wafer being attached to the head and contacting the surface of the polishing pad formed on the platen And the platen and the head are relatively moved while reacting, thereby mechanically flattening the uneven portion of the wafer surface.

The polishing pad is an essential raw material that plays an important role in the CMP process. The polishing pad is generally made of a polyurethane resin and has grooves on the surface for a large flow of the slurry and pores for supporting a fine flow pore.

The pores in the polishing pad can be formed by using a solid phase foam having a void, an inert gas, a liquid material, fiber, or the like, or by generating a gas by a chemical reaction (Korean Patent No. 10-0495404 10-0804275). The pores are the microfluidic channels of the slurry supplied onto the polishing pad and play an important role in the interaction between the slurry and the wafer. A polishing pad having a relatively large pore is rich in the amount of slurry flow, but the amount of reaction abrasive that rubs against the wafer is small and a low polishing rate may arise. On the other hand, a polishing pad having a relatively small pore has a relatively small amount of slurry flow, but an abundant amount of reactive abrasive material abrading the wafer can increase the polishing efficiency. That is, in a chemical and physical polishing process, the pores perform various roles depending on their respective sizes.

Korean Patent No. 10-0495404 Korean Patent No. 10-0804275

Therefore, it is an object of the present invention to provide a porous polyurethane polishing pad having a mesopore having a relatively large particle diameter and a fine pore having a relatively small particle size by using two or more volatile liquid phase foaming agents having different boiling points in the production of a polyurethane polishing pad And a method for manufacturing the same.

In order to achieve the above object,

And a step of molding while forming pores by injecting a liquid foaming agent when the urethane-based prepolymer and the curing agent are mixed,

Wherein the liquid foam blowing agent comprises two or more volatile liquid foam blowing agents having different boiling points.

The porous polyurethane polishing pad produced according to the manufacturing method of the present example uniformly possessed multiple pores such as a large pore (mesopore) and a small pore (fine pore), thereby improving the polishing efficiency through the fine pores, The flow amount of the slurry is increased through the pores, thereby enhancing the overall polishing efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view of a polyurethane produced using a polyurethane produced using a low boiling point blowing agent, a polyurethane produced using a high boiling point foaming agent, and two types of foaming agents having different boiling points.
2 is a graph showing the distribution of the particle diameter of the polishing pad prepared in Example 1 and Comparative Examples 1 and 2.

The method of manufacturing a porous polyurethane polishing pad of one embodiment includes forming a pore while forming a pore by injecting a liquid foaming agent when the urethane prepolymer and the curing agent are mixed,

The liquid blowing agent includes two or more volatile liquid phase blowing agents having different boiling points.

The term "prepolymer" generally means a polymer having a relatively low molecular weight in which a degree of polymerization is interrupted at an intermediate stage in order to easily form a final molded product. The prepolymer can be molded on its own or after reacting with another polymerizable compound, for example, by reacting an isocyanate compound with a polyol to prepare a prepolymer.

The urethane-based prepolymer may be a compound having an isocyanate terminal group of 5 to 15%, which is polymerized by the reaction of an isocyanate and a polyol.

Examples of the isocyanate compound used for preparing the urethane-based prepolymer include toluene diisocyanate (TDI), naphthalene-1,5-diisocyanate, paraphenylene diisocyanate p-phenylene diisocyanate, tolylene diisocyanate, 4,4'-diphenyl methane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, May be at least one isocyanate selected from the group consisting of dicyclohexylmethane diisocyanate and isoporone diisocyanate.

The polyol used in the production of the urethane-based prepolymer may be, for example, a polyether polyol, a polyester polyol, a polycarbonate polyol, and an acryl polyol Lt; RTI ID = 0.0 > polyol. ≪ / RTI > The polyol may have a weight average molecular weight (Mw) of 300 to 3,000 g / mol.

The urethane prepolymer may have a weight average molecular weight (Mw) of 500 to 3,000 g / mol. Specifically, the urethane-based prepolymer may have a weight average molecular weight of 600 to 2,000 g / mol, or 800 to 1,000 g / mol.

The urethane-based prepolymer may be prepared by reacting an isocyanate compound and a chain extender of low molecular weight together with a polyol. That is, the urethane-based prepolymer may be a polymer compound having an NCO end, which is polymerized by the reaction of an isocyanate as described above with a polyol and a chain extender having a low molecular weight. At this time, the low molecular weight chain extender may be an alcohol compound or an amine compound having a molecular weight of 50 to 300 g / mol.

The curing agent may include at least one compound selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols. Specifically, the curing agent is selected from the group consisting of 4,4'-methylenebis (2-chloroaniline) (MOCA), diethyltoluenediamine, diaminodiphenyl methane, diaminodiphenylsulphone, m-xylylene diamine, isophorone diamine, ethylenediamine, diethylenetriamine, triethylenetetramine, polypropylenediamine, and the like. Polypropylenetriamine, ethylene glycol, diethyleneglycol, dipropyleneglycol, butanediol, hexanediol, glycerine, and trimethylolpropane (also referred to as " trimethylolpropane). < / RTI >

As an example, the urethane-based prepolymer may be prepared by reacting 4,4'-diphenylmethane diisocyanate as an isocyanate compound, polytetramethylene ether glycol as a polyol, 1,4-butanediol as a chain extender, g / mol weight average molecular weight (Mw). At this time, at least one of 4,4'-methylenebis (2-chloroaniline) and diethyltoluene diamine may be used as a curing agent.

The liquid foam blowing agent is added to the reaction between the prepolymer and the curing agent to form a pore, and does not participate in the reaction between the prepolymer and the curing agent. In addition, the liquid phase foaming agent is physically vaporized by the heat generated during mixing and reaction of the prepolymer and the curing agent to form pores.

The liquid blowing agent includes two or more volatile liquid phase blowing agents having different boiling points. Specifically, the volatile liquid phase foaming agent may include at least one low boiling point liquid phase foaming agent and at least one high boiling point liquid phase foaming agent.

The volatile liquid phase foaming agent does not react with an isocyanate group, an amide group and an alcohol group, and may be in a liquid state at 25 ° C. Specifically, the volatile liquid foam blowing agent may be selected from the group consisting of 2,2-dichloro-1,1,1-trifluoroethane, 1,1-dichloro-1-fluoro But are not limited to, 1,1-dichloro-1-fluoroethane, cyclopentane, n-pentane, cyclohexane, n-butyl acetate, Butyl (trifluoromethyl) amine (bis (nonafluorobutyl) (trifluoromethyl) amine); And perfluoro compounds such as perfluorotributylamine, perfluoro-N-methylmorpholine, perfluorotripentylamine, and perfluorohexane. ≪ / RTI >

FC-70 (3M), FC-70 (3M), FC-70 (3M), FC-770 -3283 (3M Company), FC-3284 (3M Company), and the like.

The low boiling point liquid blowing agent is vaporized at the beginning of the reaction to form a mesopore having an average particle diameter of 45 to 90 탆. Specifically, the low boiling point liquid foam blowing agent may have a boiling point of 30 to 100 ° C at 1 atm. More specifically, the low boiling point liquid foam blowing agent may have a boiling point of 40 to 70 ° C at 1 atm. More specifically, the low boiling point liquid blowing agent is selected from the group consisting of 2,2-dichloro-1,1,1-trifluoroethane, 1,1-dichloro-1-fluoroethane, cyclopentane, cyclohexane, N-methylmorpholine, perfluorohexane, and the like.

Commercially available products of the low boiling point liquid blowing agent include FC-72 (3M Company), FC-770 (3M Company) and FC-3284 (3M Company).

The high-boiling point liquid phase blowing agent is retarded to form fine pores having an average particle diameter of 20 to 50 mu m. Specifically, the high boiling point liquid foam blowing agent may have a boiling point of 100 to 250 ° C at 1 atm. More specifically, the high boiling point liquid foam blowing agent may have a boiling point of 100 to 200 ° C at 1 atm. More specifically, the high boiling point liquid blowing agent may be at least one selected from the group consisting of n-butyl acetate, bis (nonafluorobutyl) (trifluoromethyl) amine, perfluorotributylamine and perfluorotripentylamine have.

Examples of commercial products of the high boiling point liquid blowing agent include FC-40 (3M Company), FC-43 (3M Company), FC-70 (3M Company), FC-3283 (3M Company)

The liquid phase foaming agent having a low boiling point and the liquid phase foaming agent having a high boiling point may have a boiling point difference of 20 to 80 캜, specifically, 50 to 80 캜. Specifically, a combination of cyclopentane and n-butyl acetate may be mentioned as a combination of a low-boiling-point liquid-phase blowing agent and a high boiling-point liquid-phase blowing agent.

The volatile liquid phase foaming agent may include a low boiling point liquid phase foaming agent and a high boiling point liquid phase foaming agent in a molar ratio of 1: 0.5 to 2. [ Specifically, the volatile liquid phase foaming agent may include a low boiling point liquid phase foaming agent and a high boiling point liquid phase foaming agent at a molar ratio of 1: 0.8 to 1.2.

The liquid foam blowing agent may be added in an amount of 1 to 10 parts by weight based on 100 parts by weight of the urethane prepolymer. Specifically, the liquid foaming agent may be added in an amount of 2 to 8 parts by weight based on 100 parts by weight of the urethane prepolymer.

The surfactant may be further mixed with the curing agent when the urethane-based prepolymer is mixed with the curing agent.

The surfactant serves to enhance the stability of pores when forming pores, and for example, a silicone surfactant may be used. Wherein the silicone surfactant comprises a block comprising dimethyl siloxane; And copolymers containing blocks comprising at least one segment selected from the group consisting of ethers, esters, amides and carbonates.

Commercially available surfactants include L-7500, L-5614, L-1580 of Niax (trademark) of Momentive Performance Materials; DC-193, DC-5604 and DC-5164 from Air Products and Chemicals; DC-309, 5098EU and Q2-5211 from Dow Corning Corporation; B-8407, B-8409, B-8418, B-8423, B-8433, B-8444, B-8450, B-8453 and B-8460 of Evonik Co., , B-8461, B-8462, B-8465, B-8466, B-8467 and B-8470.

The surfactant may be contained in an amount of 0.3 to 5 parts by weight based on 100 parts by weight of the urethane prepolymer. Specifically, the surfactant may be contained in an amount of 2 to 4 parts by weight based on 100 parts by weight of the urethane prepolymer.

The urethane-based prepolymer, the curing agent and the liquid foaming agent are put into the mixing process substantially at the same time. As an example, the raw materials including the urethane-based prepolymer, the curing agent and the liquid foaming agent may be added together into a mixing head made of aluminum, Stanisstile or the like. The urethane prepolymer and the curing agent are mixed with each other by stirring in the mixing head to initiate the reaction. The liquid foaming agent is dispersed evenly in the raw material. When the temperature in the mixing head rises as the reaction proceeds, the liquid foaming agent vaporizes to form pores .

The stirring may be performed at 100 to 10,000 rpm, or 100 to 7,000 rpm. When the stirring speed is within the above range, it is more advantageous that the liquid foaming agent is uniformly dispersed in the raw material.

The urethane-based prepolymer, the curing agent and the liquid foaming agent can be put into the mixing process at a constant rate.

The urethane-based prepolymer and the curing agent may be mixed in a molar equivalent ratio of 1: 0.8 to 1.2, or a molar equivalent ratio of 1: 0.9 to 1.1, based on the molar amount of the respective reactive groups. Here, the "molar number basis of each reactor" means, for example, based on the molar number of isocyanate group of the urethane prepolymer and the molar number of the reactive group (amine group, alcohol group, etc.) of the curing agent. Therefore, the urethane-based prepolymer and the curing agent can be supplied at a constant rate in the mixing process by controlling the charging rate so as to be charged per unit time in an amount satisfying the molar equivalent ratio exemplified above.

The urethane-based prepolymer and the curing agent react with each other after mixing to form a solid polyurethane, which is then formed into a sheet or the like. Specifically, the isocyanate terminal group of the urethane-based prepolymer may react with an amine group, an alcohol group, water, or the like of the curing agent.

At this time, the liquid foaming agent vaporizes in the raw material to form pores without participating in the reaction between the urethane prepolymer and the curing agent.

The molding may be performed using a mold. Specifically, raw materials (urethane type prepolymer, curing agent and liquid blowing agent) sufficiently stirred in a mixing head or the like are discharged into a mold to fill the inside of the mold. Further, the reaction between the urethane-based prepolymer and the curing agent is completed in the mold, so that a molded article in the form of a cake in the form of a solid state can be obtained in the shape of the mold.

After molding, the molded body obtained from the mold can be appropriately sliced or cut into a sheet for the production of a polishing pad.

As an example, a plurality of sheets for polishing pads can be manufactured at once by molding using a mold having a height of 5 to 50 times the thickness of the polishing pad to be finally produced, and then slicing the molded body at equal thickness intervals. Accordingly, the height of the mold is made to be about 5 to 50 times the thickness of the polishing pad to be finally produced, and the sheet can be produced by molding. However, the sliced sheets may have pores of different average particle diameters depending on the molded position in the mold. That is, in the case of a sheet formed at the lower part of the mold, the sheet formed at the upper part of the mold has pores having a larger particle size than the sheet formed at the lower part, while having pores with a minute particle diameter.

Therefore, in order to have uniform pore size per sheet, it is preferable to use a mold capable of producing one sheet by one molding. For this purpose, the height of the mold should not significantly differ from the thickness of the porous polyurethane polishing pad to be produced. For example, the forming can be performed using a mold having a height corresponding to one to three times the thickness of the porous polyurethane polishing pad to be finally produced. Specifically, the mold may have a height of 1.1 to 2.5 times, or 1.2 to 2 times the thickness of the porous polyurethane polishing pad to be finally produced.

After molding, the molded body obtained from the mold can be appropriately sliced or cut into a sheet for the production of a polishing pad. Specifically, a step of cutting each of the upper and lower ends of the molded body obtained from the mold after the molding may be further performed. More specifically, after the molding, each of the upper and lower ends of the molded body obtained from the mold can be cut. By thus partially removing upper and lower portions having a relatively large deviation of the particle diameter after the production of the molded article, it is possible to further reduce the deviation of the particle diameter. More specifically, each of the upper and lower ends of the molded body may be cut by 1/22 to 3/10, or 1/12 to 1/4 of the total thickness of the molded body.

As a specific example, the mold has a height corresponding to 1.2 to 2 times the thickness of the porous polyurethane polishing pad to be finally manufactured, and the upper and lower ends of the molded body obtained from the mold after the molding are respectively set to 1 / 12 to 1/4.

The manufacturing method may further include a step of machining a groove on the surface after the surface cutting, a bonding step with a lower layer portion, an inspection step, a packaging step, and the like. These processes can be carried out in the manner of a conventional polishing pad manufacturing method.

The size of the pores in the polishing pad can be controlled through the reaction temperature of the urethane prepolymer and the curing agent, and the type of the liquid foaming agent. In addition, the number of pores in the polishing pad and the density of the pores can be controlled through the content of the liquid foamable agent and the molding temperature.

The porous polyurethane polishing pad manufactured according to the manufacturing method of the embodiment has a uniform pore (mesopore 200) and a small pore (fine pore 100), uniformly having multiple pores (see FIG. 1) The polishing efficiency is increased and the flow amount of the slurry is increased through the mesopore, thereby improving the overall polishing efficiency.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[ Example ]

Example  One. Of the polishing pad  Produce

In a casting apparatus equipped with a urethane-based prepolymer (SKC Company, SKSH-600D, weight average molecular weight: 900 g / mol, NCO%: 9.1), a curing agent and a liquid blowing agent injection line, a urethane prepolymer and a surfactant B8404 Ltd.), and the hardener tank was filled with diethyltoluene diamine (manufactured by Lonza). The surfactant was added in an amount of 3 parts by weight based on 100 parts by weight of the urethane prepolymer.

Thereafter, 46.5 g (0.4 mol, 4.65 parts by weight based on 100 parts by weight of the urethane prepolymer) of n-butyl acetate (boiling point at 1 atm: 126.1 캜) and 28 g (0.4 mol, urethane 2.8 parts by weight based on 100 parts by weight of the prepolymer) was injected with cyclopentane (boiling point at 1 atm: 49.2 DEG C), stirred at 200 rpm, and discharged at a rate of 10 kg / min. The discharged material was injected into a mold having a width of 1,000 mm, a length of 1,000 mm and a height of 3 mm and solidified to obtain a solid-cake-shaped molded article. Then, the upper and lower ends of the molded body were cut to obtain one polishing pad having a thickness of 2 mm.

Comparative Example  One

A polishing pad was prepared in the same manner as in Example 1, except that 93 g (0.8 mol) of n-butyl acetate was added as a volatile liquid phase blowing agent.

Comparative Example  2

A polishing pad was produced in the same manner as in Example 1 except that only 56 g (0.8 mol) of cyclopentane was added as a volatile liquid phase blowing agent.

Test Example

The properties of the polishing pads prepared in the above Examples and Comparative Examples were measured according to the following conditions and procedures and are shown in Table 1 below. Fig. 2 shows the distribution of the fore-ground particle size.

(1) Hardness: Shore D hardness was measured, and the polishing pad was cut into a size of 2 cm × 2 cm (thickness: 2 mm) and allowed to stand in an environment of 23 ± 2 ° C. and a humidity of 50 ± 5% for 16 hours. The pads were superimposed to a thickness of 6 mm and the hardness of the polishing pad was measured using a hardness meter (D-type hardness meter).

(2) Specific gravity: The polishing pad was cut into a rectangle (thickness: 2 mm) having a size of 4 cm x 8.5 cm, and then allowed to stand for 16 hours in an environment of temperature 23 ± 2 ° C. and humidity 50 ± 5%. The specific gravity of the polishing pad was measured using a hydrometer.

(3) Pore average particle diameter: The polishing pad was cut parallel to a thickness of 1 mm or less with a microtome cutter as thin as possible, the sample was fixed on a slide glass, and observed with a scanning electron microscope (SEM) at 100 times. The total pore size was measured from the image obtained using the image analysis software, and the pore average particle size and the pore size distribution were calculated.

(4) Pore density: Data were used for the analysis of the pore diameter, and the pore density value was obtained from the ratio of the area occupied by the total pores to the total area of the photograph of the square.

Comparative Example 1 Comparative Example 2 Example 1 Hardness (Shore D) 51.4 52.3 52.0 Specific gravity (g / cm3) 0.78 0.79 0.77 Pore average particle diameter (占 퐉) 44 66 55 Pore density (%) 38 39 39

As shown in Table 1 and FIG. 2, it was confirmed that the polishing pad of Example 1 using two kinds of volatile liquid phase foaming agents having different boiling points contained both mesopores and micropores uniformly.

100: fine pore 200: mesophore

Claims (12)

And a step of molding while forming pores by injecting a liquid foaming agent when the urethane-based prepolymer and the curing agent are mixed,
Wherein the liquid phase foaming agent comprises two or more kinds of volatile liquid phase foaming agents having different boiling points,
Wherein the volatile liquid blowing agent comprises at least one low boiling point liquid blowing agent and at least one high boiling point liquid blowing agent,
The low boiling point liquid foam blowing agent has a boiling point of 30 to 100 DEG C at 1 atm,
Wherein the high boiling point liquid foam blowing agent has a boiling point of 100 to 250 DEG C at 1 atm,
A method for producing a porous polyurethane polishing pad having a boiling point of 20 to 80 占 폚 between a liquid phase foaming agent having a low boiling point and a liquid phase foaming agent having a high boiling point.
delete delete The method according to claim 1,
Wherein the volatile liquid phase foaming agent comprises a low boiling point liquid phase foaming agent and a high boiling point liquid phase foaming agent in a molar ratio of 1: 0.5 to 2. [
The method according to claim 1,
Wherein said volatile liquid blowing agent is liquid at 25 占 폚 without reacting with isocyanate, amide and alcohol groups.
6. The method of claim 5,
Wherein said volatile liquid blowing agent is selected from the group consisting of 2,2-dichloro-1,1,1-trifluoroethane, 1,1-dichloro-1-fluoroethane, cyclopentane, n-pentane, cyclohexane, n- (Nonafluorobutyl) (trifluoromethyl) amine, perfluorotributylamine, perfluoro-N-methylmorpholine, perfluorotripentylamine and perfluorohexane, ≪ / RTI >
The method according to claim 1,
Wherein the liquid foaming agent is added in an amount of 1 to 10 parts by weight based on 100 parts by weight of the urethane prepolymer.
The method according to claim 1,
Wherein the urethane-based prepolymer is a compound having an isocyanate terminal group of 5 to 15%, which is polymerized by the reaction of an isocyanate and a polyol.
The method according to claim 1,
Wherein the curing agent comprises at least one compound selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols and aliphatic alcohols.
The method according to claim 1,
Wherein the surfactant is further mixed when mixing the urethane-based prepolymer and the curing agent.
The method according to claim 1,
Further comprising the step of cutting said upper and lower ends of a molded body obtained from said mold after said molding is performed using a mold.
12. The method of claim 11,
The mold having a height corresponding to 1.2 to 2 times the thickness of the porous polyurethane polishing pad to be finally produced,
Wherein the cutting cuts each of the upper and lower ends of the formed body by 1/12 to 1/4 of the total thickness of the formed body.

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