KR102608960B1 - Method of manufacturing polishing pad for manufacturing integrated circuit device - Google Patents

Abstract

To manufacture a polishing pad, a urethane prepolymer is formed. The reactant is formed by reacting the urethane prepolymer and the curing agent. A physical foaming agent and an inert gas are sequentially applied to the reactants, and the reactants are mixed to form a crude polyurethane product. While suppressing vaporization of the physical foaming agent by the inert gas, the physical foaming agent is vaporized using the reaction heat generated from the crude polyurethane product. The crude polyurethane product is gelled. The crude gelled polyurethane product is cured to form a porous polyurethane polishing layer including a plurality of pores.

Description

{Method of manufacturing polishing pad for manufacturing integrated circuit device}

The technical idea of the present invention relates to a method of manufacturing a polishing pad, and particularly to a polishing pad used in manufacturing an integrated circuit device and a method of manufacturing the same.

In the manufacture of integrated circuit devices, a CMP (chemical mechanical polishing) process is used to secure the required global flatness on the surface of a substrate such as a semiconductor wafer, glass, etc., and the surfaces of various films formed thereon. As wafers become larger in diameter, integrated circuit devices become more integrated, line widths become smaller, and wiring structures become more multilayered, there is a growing demand for the development of technology that can produce polishing pads that can improve polishing speed and flatness in the CMP process. .

The technical problem to be achieved by the technical idea of the present invention is to provide a method of manufacturing a polishing pad that can maximize polishing performance and planarization performance by collecting polishing slurry in a uniform and fine size during the CMP process for manufacturing integrated circuit devices. .

In a method of manufacturing a polishing pad for manufacturing an integrated circuit device according to an aspect according to the technical idea of the present invention, a urethane prepolymer is formed. The reactant is formed by reacting the urethane prepolymer and the curing agent. A physical foaming agent and an inert gas are sequentially applied to the reactants, and the reactants are mixed to form a crude polyurethane product. While suppressing vaporization of the physical foaming agent by the inert gas, the physical foaming agent is vaporized using the reaction heat generated from the crude polyurethane product. The crude polyurethane product is gelled. The crude gelled polyurethane product is cured to form a porous polyurethane polishing layer including a plurality of pores.

In a method of manufacturing a polishing pad for manufacturing an integrated circuit device according to another aspect according to the technical spirit of the present invention, a urethane prepolymer having a viscosity of 20,000 to 40,000 cps at 25° C. is formed. A crude polyurethane product is formed using the urethane prepolymer, a curing agent, a foaming agent with a boiling point of 60 to 150° C., and an inert gas. While suppressing vaporization of the physical foaming agent by the inert gas, the physical foaming agent is vaporized using the reaction heat generated from the crude polyurethane product. The crude polyurethane product is gelled. The crude gelled polyurethane product is cured to form a porous polyurethane polishing layer including a plurality of pores.

According to the method of manufacturing a polishing pad for manufacturing integrated circuit elements according to the technical idea of the present invention, the average size of the plurality of pores formed in the polishing pad is relatively small, the size deviation of each of the plurality of pores is small, and the plurality of pores are formed in the polishing pad. It can be distributed relatively evenly within. Additionally, the life time of the polishing pad can be increased and the cost of replacing the polishing pad can be reduced. Accordingly, the reliability of the CMP process can be improved in the manufacturing process of miniaturized integrated circuit devices by maximizing polishing performance and planarization performance by collecting the polishing slurry in a uniform and fine size during the CMP process for manufacturing integrated circuit devices. The manufacturing cost of integrated circuit devices can be reduced.

1 is a flowchart for explaining a method of manufacturing a polishing pad according to embodiments of the present invention.
Figure 2 is a cross-sectional view of a polishing pad manufactured according to a method of manufacturing a polishing pad according to embodiments of the present invention.
Figure 3 is a partially cut away perspective view schematically showing main parts of a polishing device that polishes a substrate using a polishing pad according to an embodiment of the technical idea of the present invention.
4A and 4B are images of a plurality of pores on the polished surface of a polishing layer obtained according to embodiments of the technical idea of the present invention.
5A and 5B respectively show the polished surface before the CMP process (PRE-CMP) and the polished surface after the CMP process (POST-CMP) using the polishing layer obtained according to the embodiments according to the technical idea of the present invention. This diagram shows enlarged photos comparing the condition of the polished surface.
Figure 6 is a photograph of the polished surface of a polishing layer obtained according to embodiments of the technical idea of the present invention, and is a view showing the state of a plurality of open pores exposed on each polished surface.
Figure 7 is a graph showing the results of evaluating the average pore size change in the polishing layer obtained according to embodiments of the technical idea of the present invention according to the viscosity of the urethane prepolymer.
Figure 8 is a graph evaluating the average pore size change in the polishing layer obtained according to embodiments of the technical idea of the present invention according to the boiling point of the physical foaming agent.
Figure 9 is a graph evaluating the average pore size change of a plurality of pores in a polishing layer obtained according to embodiments of the technical idea of the present invention formed in the polishing layer according to the content of an inert gas and the content of a physical foaming agent.
Figure 10a is a graph evaluating the polishing speed of a tungsten (W) film when the tungsten (W) film was polished for about 1 hour using a polishing layer obtained according to embodiments according to the technical idea of the present invention.
Figure 10b is a graph evaluating the lifetime characteristics when polishing a tungsten film using a polishing layer obtained according to embodiments of the technical idea of the present invention.
Figure 11a is a graph evaluating the polishing speed of the silicon oxide film when the silicon oxide film was polished for about 1 hour using a polishing layer obtained according to embodiments of the technical idea of the present invention.
Figure 11b is a graph evaluating the lifetime characteristics when polishing a silicon oxide film using a polishing layer obtained according to embodiments of the technical idea of the present invention.
Figure 12a shows the surface roughness on the polished surface of each polishing layer after performing a CMP process using the polishing layer obtained according to the embodiments according to the technical idea of the present invention, and the average length of the roughness curve element of the corresponding polishing surface. This is a graph showing the results of evaluation using (Rsm: mean width of profile elements).
Figure 12b is an average of polishing pad debris separated from the polishing surface of the polishing layer during the CMP process after performing a CMP process using a polishing layer obtained according to embodiments of the present invention. This is a graph showing the results of evaluating the size.
Figure 12c is a graph showing the results of evaluating the number of scratches formed on the surface of the film to be polished remaining on the wafer after performing a CMP process using a polishing layer obtained according to embodiments of the technical idea of the present invention. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same components in the drawings, and duplicate descriptions thereof are omitted.

1 is a flowchart for explaining a method of manufacturing a polishing pad according to embodiments of the present invention.

Referring to Figure 1, in process P10, a urethane prepolymer (prepolymer) is formed.

To form the urethane prepolymer, a plurality of polyols having different structures and an isocyanate compound can be reacted. As used herein, the term “polyol” refers to a compound having two or more -OH groups in one molecule.

A plurality of polyols used in the method of manufacturing a polishing pad according to embodiments of the present invention include at least one polyol having at least four, for example, 4 to 8 -OH groups at the terminal of the urethane prepolymer. It may be included in an amount of about 1 to 30% by weight based on the total weight. Each of the plurality of polyols may have a number average molecular weight (Mn) of about 500 to 10,000. Unless otherwise defined herein, molecular weight means number average molecular weight (Mn). The plurality of polyols are polypropylene glycol, polyurethane, polyether, polyester, polysulfone, polyacrylic, polycarbonate, polyethylene, polymethyl methacrylate, polyvinyl acetate, polyvinyl chloride, polyethylene imine, and polyether sulfone. , polyether imide, polyketone, melamine, nylon, and fluorinated hydrocarbon compounds, but the technical idea of the present invention is not limited thereto.

In step P10, in forming the urethane prepolymer, a plurality of polyols having different structures may be reacted with an isocyanate compound to form a urethane prepolymer containing unreacted -NCO groups. The unreacted -NCO group in the urethane prepolymer may react with the curing agent in the subsequent process P20 to form a reactant.

The isocyanate compound may be an isocyanate compound having two or more isocyanate groups, for example, 2 to 5 isocyanate groups. The isocyanate compound may be comprised of an aromatic isocyanate compound and/or an aliphatic isocyanate compound. The isocyanate compounds include toluene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), and hexamethylene diisocyanate (HMDI). , isophorone diisocyanate (IPDI), p-phenylene diisocyanate, or a combination thereof.

In process P10, the urethane prepolymer may be formed to have a viscosity of about 20,000 to 40,000 cps at 25°C.

The viscosity of the urethane prepolymer, along with the physical foaming agent and inert gas described later in process P30, may contribute to determining the size of each of the plurality of pores included in the polishing pad. A more detailed description of this will be provided later with reference to FIGS. 2 and 3.

In step P20, the urethane prepolymer obtained in step P10 and the curing agent are reacted to form a reactant.

A crosslink is formed by the reaction between the urethane prepolymer and the curing agent, and as a result, polyurethane with a three-dimensional network structure may be formed.

In some embodiments, an amine compound may be used as the curing agent. For example, the curing agent may be composed of an aliphatic or aromatic amine compound. For example, the curing agent may be ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, or 4,4'-(methylenebis-o-chloroaniline) (MOCA ), but is not limited to the above examples.

In step P30, a physical foaming agent and an inert gas are sequentially applied to the reactants obtained in step P20 while the reactants are mixed to form a crude polyurethane product.

The term "physical foaming agent" used herein refers to a foaming agent that does not vaporize at room temperature but has a relatively low boiling point, unlike a chemical foaming agent that causes foaming by a chemical reaction. It vaporizes through a urethane reaction and causes physical foaming. It is used to mean.

The physical foaming agent can be mixed with the crude polyurethane product to generate a large amount of bubbles through vaporization by heat. The physical blowing agent may not participate in chemical reactions within the crude polyurethane product.

In some embodiments, the physical blowing agent may be composed of a compound containing a halogen element. In some embodiments, the physical blowing agent may be comprised of freon, a hydrocarbon compound, a perfluorinated compound, or a combination thereof. Examples of the freon include CCl ₃ F (boiling point 23.8°C), CHCl ₂ CF ₃ (boiling point 28.7°C), and CH ₃ CCl ₂ F (boiling point 32°C). As the hydrocarbon compounds, n-pentane (boiling point 36.1°C), c-pentane (boiling point 49°C), methyl cellosolve (boiling point 124°C), ethyl cellosolve (boiling point 136°C), cyclo Hexanone (cyclohexanone) (boiling point 154°C), etc. can be mentioned. As the above-mentioned perfluorinated compounds, PF-5056 (boiling point: 60°C), PF-5058 (boiling point: 80°C), etc. (PF-5056 and PF-5058 are brand names of products sold by 3M Company, St. Paul, Minnesota). perfluorinated compounds; perfluoromorpholine compounds such as C ₄ F ₉ NO (boiling point 95° C.) and its isomers; Novec 1230 (perfluoro(2-methyl-3-pentanone: C ₆ F ₁₂ O) (boiling point 49°C), etc.

In some embodiments, the physical foaming agent may have a boiling point lower than the temperature obtained by the heat of reaction of the urethane reaction. In some embodiments, a material having a boiling point of about 60 to 150° C. may be used as the physical foaming agent.

In some embodiments, the physical foaming agent may be in a liquid phase at room temperature. The term “room temperature” used in this specification is about 20 to 28° C. and may vary depending on the season.

In some embodiments, the inert gas does not participate in the urethane reaction and has a valence of '0', so it may be in a chemically stable state. For example, the inert gas may be He, Ne, Ar, Kr, Xe, Rn, N ₂ , or a combination thereof.

In some embodiments, in order to form the crude polyurethane product in step P30, a liquid physical foaming agent may be mixed with the reactant obtained by reacting the urethane prepolymer and the curing agent in step P20 to form a preliminary blend. Thereafter, the preliminary blend can be mixed while applying an inert gas to the preliminary blend.

To form the crude polyurethane product in process P30, the physical blowing agent may be applied to the reactant in an amount of about 0.1 to 10% by weight based on the total weight of the crude polyurethane product. The inert gas may be applied to the reactant in an amount of about 5 to 30% by volume based on the total volume of the crude polyurethane product.

The physical foaming agent and the inert gas induce the creation of a plurality of pores contained in the polishing pad. When other conditions are the same, the size of the plurality of pores can be controlled using the mixing ratio of the physical foaming agent and the inert gas. .

In step P40, the physical foaming agent is vaporized using the reaction heat generated from the crude polyurethane product while suppressing vaporization of the physical foaming agent with the inert gas.

In some embodiments, the temperature obtained by the heat of reaction generated from the crude polyurethane product may be about 120 to 150 ° C, and the physical blowing agent is lower than the temperature obtained by the heat of reaction and within the range of about 60 to 150 ° C. It can have a boiling point of choice.

In some embodiments, the crude polyurethane product may be provided with a tack free time (TFT) of about 10 seconds to about 30 minutes. If a reaction occurs within the crude polyurethane product during the TFT to generate heat of reaction that provides a temperature above the boiling point of the physical blowing agent, the physical blowing agent may be vaporized during the TFT. At this time, the inert gas may play a role in controlling excessive vaporization of the physical foaming agent. At this time, the equilibrium is broken by the heat of reaction of the crude polyurethane product, and a crosslinking reaction occurs between the reactive groups constituting the crude polyurethane product, so that the crude polyurethane product may have a more dense and fine three-dimensional network structure.

In step P50, the crude polyurethane product is gelled.

The gelation process may be performed for about 5 to 30 minutes at a temperature of about 80 to 90 ° C., but the technical idea of the present invention is not limited thereto, and the specific gelation temperature and gelation time may be adjusted to optimal conditions depending on the case. It can be changed in various ways.

In step P60, the gelled polyurethane crude product is cured to form a porous polyurethane polishing layer including a plurality of pores.

The crude gelled polyurethane product may be solidified by the curing. The curing may be performed for about 20 to 24 hours at a temperature of about 80 to 120 ℃, but the technical idea of the present invention is not limited thereto, and the specific curing temperature and curing time may be adjusted to meet optimal conditions depending on the case. It can change in various ways.

In step P70, the porous polyurethane polishing layer obtained in step P60 is processed to form a polishing surface where a plurality of pores are exposed. For example, the polishing surface may correspond to the polishing surface 128, which will be described later with reference to FIG. 2.

The process of processing a porous polyurethane polishing layer according to process P70 includes cutting the porous polyurethane polishing layer into a sheet shape to have a predetermined thickness and a predetermined planar shape, and cleaning the cut porous polyurethane polishing layer. It may include a process of forming grooves of various shapes on the polishing surface of the cleaned porous polyurethane polishing layer so that the polishing slurry can be evenly supplied to the polishing surface. In some embodiments, the groove forming process can be omitted.

In some embodiments, a polishing pad may be completed using only the porous polyurethane polishing layer obtained through the above processes. In some other embodiments, the polishing pad may be completed by combining a porous polyurethane polishing layer with a support layer, for example, the support layer 110 as illustrated in FIG. 2.

The polishing pad manufactured by the method according to the technical idea of the present invention described with reference to FIG. 1 may include a plurality of pores of fine and uniform size, and the plurality of pores may be relatively uniformly distributed within the polishing pad. there is.

Figure 2 is a cross-sectional view of a polishing pad 100 manufactured according to a method of manufacturing a polishing pad according to embodiments of the present invention.

Referring to FIG. 2, the polishing pad 100 includes a support layer 110 and a polishing layer 120.

FIG. 3 is a partial cutaway perspective view schematically showing main parts of the polishing device 200 that polishes the substrate W using the polishing pad 100. Although the rotary polishing device 200 is illustrated in FIG. 3, the technical idea of the present invention is not limited to the rotary polishing device.

Referring to FIGS. 2 and 3 , the support layer 110 may serve to support the polishing pad 100 so that it can be attached to the platen 202 of the polishing device 200 . The support layer 110 is made of a material that has resilience against the force pressing the substrate W, which is the polishing target, loaded on the head 204 facing the platen 202, so that the polishing layer 120 formed thereon ) can play the role of supporting the substrate (W) with uniform elastic force. The support layer 110 may be made of a non-porous solid uniform elastic material. The support layer 110 may have a lower hardness than the hardness of the polishing layer 120. At least a portion of the support layer 110 may be made of a transparent or translucent material. In some embodiments, support layer 110 can be omitted.

In FIG. 3 , the substrate W may be, for example, a wafer on which a polishing target film, such as a metal or an insulating layer, is formed. The substrate W may be made of various substrates, such as a substrate for forming a semiconductor device, a substrate for forming a TFT-LCD, a glass substrate, a ceramic substrate, or a polymer substrate.

Although FIG. 3 illustrates the case where the polishing pad 100 has a circular planar shape, it can be modified into various shapes such as rectangular or square depending on the shape of the polishing device 200.

The polishing layer 120 may be in direct contact with the substrate W to be polished. The polishing layer 120 may be manufactured by the polishing pad manufacturing method as described with reference to FIG. 1 .

The polishing layer 120 can be obtained by processing the porous polyurethane polishing layer formed in process P60 of FIG. 1 into a predetermined shape according to process P70. For example, the cured porous polyurethane polishing layer obtained in process P60 is processed. After being cut into a sheet shape to have a predetermined thickness and a predetermined plane shape according to P70 and cleaned, grooves of various shapes are formed on the polishing surface 128 so that the polishing slurry can be evenly supplied to the polishing surface 128. It may be the result of forming (not shown).

The polishing layer 120 may include a polymer matrix 122 and a plurality of pores 126 dispersed within the polymer matrix 122.

The polishing layer 120 made of a porous polyurethane polishing layer may be insoluble in the polishing slurry 214, which is a chemical solution used to perform the CMP process. Additionally, as illustrated in FIG. 3, the polishing slurry 214 supplied through the nozzle 216 of the polishing device 200 may not penetrate into the interior of the polishing layer 120 made of a porous polyurethane polishing layer.

In the method of manufacturing a polishing pad according to embodiments of the technical idea of the present invention, as described in process P10 of FIG. 1, a plurality of polyols having different structures and an isocyanate compound are reacted to form a urethane prepolymer. Here, the plurality of polyols may include at least one polyol having at least 4 -OH groups.

For example, when a plurality of polyols include polypropylene glycol having at least 4 -OH groups, the resulting polishing pad ( 100) characteristics can be improved. More specifically, when the polishing layer 120 is made of polyurethane, there are many repetitive two-dimensional bonds of the -C-O- structure in the polyurethane structure obtained by using only a polyol having a divalent or trivalent -OH group as the polyol. It can exhibit relatively flexible characteristics. On the other hand, as in the method of manufacturing a polishing pad according to embodiments of the technical idea of the present invention, when polyurethane is formed using a plurality of polyols containing a polyol having a tetravalent or more -OH group, the resulting product is The polyurethane structure can provide a dense and fine three-dimensional network structure by having a relatively high degree of cross-linking. Therefore, it can exhibit rigid characteristics compared to the case of using only a polyol having a divalent or trivalent functional group.

In the method of manufacturing a polishing pad according to embodiments of the technical idea of the present invention, at least one polyol having at least 4 -OH groups may be included in an amount of about 1 to 30% by weight based on the total weight of the urethane prepolymer. You can. For example, when forming a urethane prepolymer using a plurality of polyols mixed with a polyol having a divalent -OH group, a polyol having a trivalent -OH group, and a polyol having at least a tetravalent -OH group, the polyol is included in the plurality of polyols. The content of the polyol having at least tetravalent -OH groups may be about 1 to 30% by weight based on the total weight of the resulting urethane prepolymer. When the content of the polyol having at least a tetravalent -OH group is lower than 1% by weight based on the total weight of the urethane prepolymer, the possibility of bonding to form a three-dimensional network structure induced by the polyol having a tetravalent -OH group increases rapidly. Otherwise, crosslinking may not have a significant effect on improvement. If the content of polyol having a tetravalent -OH group is higher than 30% by weight based on the total weight of the urethane prepolymer, the flexibility of the resulting polishing pad is significantly reduced, so that the urethane prepolymer is removed during the manufacturing process of the polishing pad. It may become difficult to physically control.

The polishing pad 100 manufactured by the method according to the embodiments according to the technical idea of the present invention may have a polyurethane structure having a dense and fine three-dimensional network structure by having a relatively high degree of cross-linking. Accordingly, while performing a CMP process using the polishing device 200 illustrated in FIG. 3, a plurality of pores 126 dispersed in the polymer matrix 122 of the polishing pad 100 are formed on the polishing surface 128. It includes an exposed open pore 126A. As the polymer matrix 122 defining the open pores 126A is made of a polyurethane structure with a dense and fine three-dimensional network structure, the open pores 126A exposed from the polishing surface 128 are exposed as the CMP process progresses. Accordingly, even if high pressure and friction force are applied, the glazing phenomenon in which the surrounding area of the open pore 126A is worn away and the open pore 126A is crushed does not occur.

During the CMP process, polishing performance must be maintained constant during the life time during which the polishing pad 100 is used. However, if the open pores 126A exposed on the polishing surface 128 of the polishing pad 100 are clogged or a glazing phenomenon occurs, polishing performance will gradually deteriorate, and eventually the use time of the polishing pad 100 will be limited. You can. The polishing pad 100 manufactured by the method according to the embodiments according to the technical idea of the present invention is the lifetime of the polishing pad 100 during which the CMP process is performed, for example, the open pores 126A for about 20 hours. The shape can remain constant. Accordingly, the polishing performance of the polishing pad 100 can be maintained constant without deterioration. As a result, the life time of the polishing pad 100 can be increased, and the replacement cost of the polishing pad 100 can be reduced.

The viscosity of the urethane prepolymer formed in process P10 of FIG. 1 can determine the size of the plurality of pores 126 included in the polishing layer 120 along with the inert gas and low boiling point foaming agent used in process P30. In addition, the inert gas and low boiling point foaming agent applied to form the crude polyurethane product in process P30 of FIG. 1 induce the creation of a plurality of pores 126 included in the polishing pad 100, and the inert gas and low boiling point foaming agent are applied to form the crude polyurethane product. The size of the plurality of pores 126 dispersed in the polishing layer 120 can be controlled depending on the content of each foaming agent. In some embodiments, the size of the plurality of pores may be controlled using a mixing ratio of the physical foaming agent and the inert gas when other conditions are the same.

A fine average pore in the micrometer (μm) unit can be used to perform a fine process to manufacture a highly integrated fine integrated circuit device while ensuring that the plurality of pores 126 distributed within the polishing layer 120 have a relatively uniform size. A plurality of pores 126 may be required in size, for example, with an average pore size of about 31 μm or less. To this end, in step P10 of FIG. 1, the urethane prepolymer is formed to have a viscosity of about 20,000 to 40,000 cps at 25°C, and to form the crude polyurethane product in step P30 of FIG. 1, the physical foaming agent is used as the above. It is applied to the reactant in an amount of about 0.1 to 10% by weight based on the total weight of the crude polyurethane product, and the inert gas is added to the reactant in an amount of about 5 to 30% by volume based on the total volume of the crude polyurethane product. It can be applied to the reactant.

Among the polishing layers 120 of the polishing pad 100, some of the plurality of pores 126 are opened as open pores 126A on the polishing surface 128 that is in direct contact with the substrate W during the CMP process. In this way, the open pores 126A opened on the polishing surface 128 remain as open pores 126A as the pore area created by the inert gas and low boiling point foaming agent contained in the polishing layer 120 is exposed to the outside. , certain substances from the outside can be captured in the open pores 126A.

While performing a CMP process using the polishing pad 100, as the polishing layer 120 is gradually worn away from the polishing surface 128, a plurality of pores 126 dispersed in the polishing layer 120 are continuously formed in the polishing layer. A new open pore 126A is created by being exposed on the new polishing surface 128 of 120, and the interior of the newly created open pore 126A may be filled with the polishing slurry 214. Therefore, only the polymer matrix 122, which is the material of the polishing layer 120, can be exposed on the polishing surface 128, and the substrate W, which is the polishing target, can be polished uniformly without uneven wear of the polishing pad 100. there is.

Hereinafter, specific examples and comparative examples according to the present invention will be described. The following examples are presented to more clearly explain the method of manufacturing a polishing pad according to the technical idea of the present invention through specific examples, and the technical idea of the present invention is not limited by the following examples and comparative examples. .

<Example 1>

Into a 200 kg reactor, 70 kg of polytetramethylene glycol (molecular weight 1000), 30 kg of polypropylene glycol (molecular weight 1000, functionality (f)=4), and 60 kg of toluene diisocyanate were added, and the mixture was reacted at a temperature of 70 to 80°C for 4 to 40 kg. The reaction was conducted for 5 hours to prepare a urethane prepolymer with a -NCO group content of the final reactant of 9.0%. The viscosity of the prepared urethane prepolymer was 35,000 cps (25°C).

<Example 2>

In a 200 kg reactor, 80 kg of polytetramethylene glycol (the result of mixing polytetramethylene glycol with a molecular weight of 1000 and polytetramethylene glycol with a molecular weight of 800 in a weight ratio of 8:2, i.e. molecular weight 1000/800 = 8/2), polypropylene 20 kg of glycol (molecular weight 1000/2000 = 5/5, functionality (f) = 4) and 67 kg of toluene diisocyanate were added, reacted at a temperature of 70 to 80 ℃ for 4 to 5 hours, and -NCO group of the final reactant was added. A urethane prepolymer with a content of 9.0% was prepared. The viscosity of the prepared urethane prepolymer was 30,000 cps (25°C).

<Example 3>

Using a casting machine, 100 kg of the urethane prepolymer of Example 1, 29 kg of MOCA, and N ₂ gas, an inert gas, were discharged through a mixing head rotating at 5000 rpm. At this time, N ₂ gas was applied in an amount of 30% by volume based on the total volume of the crude polyurethane product to be formed using an MFC (mass flow controller).

Thereafter, the obtained crude polyurethane product was injected into a square mold, and a TFT (tack free time) of 1 minute was provided. Afterwards, it was gelled for 30 minutes and then cured in an oven at 100°C for 20 hours.

The prepared cured material was processed to produce a polishing layer constituting a polishing pad. The average pore size on the polished surface of the polishing layer was 32 μm.

<Example 4>

Using a casting machine, 100 kg of the urethane prepolymer of Example 2, 29 kg of MOCA, N ₂ gas as an inert gas, and a physical foaming agent with a boiling point of 95° C. were discharged through a mixing head rotating at 5000 rpm. At this time, N ₂ gas was applied in an amount of 10% by volume based on the total volume of the crude polyurethane product to be formed using MFC, and the physical foaming agent was applied in an amount of 8% based on the total weight of the crude polyurethane product to be formed. It was applied as weight percent.

Thereafter, the obtained crude polyurethane product was injected into a square mold and subjected to TFT for 1 minute. Afterwards, it was gelled for 30 minutes and then cured in an oven at 100°C for 20 hours.

The prepared cured material was processed to produce a polishing layer constituting a polishing pad. The average pore size on the polished surface of the polishing layer was 29 μm.

<Example 5>

A crude polyurethane product was obtained in a similar manner to Example 4. However, in this example, N ₂ gas was applied in an amount of 15% by volume based on the total volume of the crude polyurethane product to be formed, and the physical foaming agent was applied in an amount of 6% by weight based on the total weight of the crude polyurethane product to be formed. Approved as %.

Thereafter, the obtained crude polyurethane product was treated in the same manner as in Example 4 to prepare a polishing layer. The average pore size on the polished surface of the polishing layer was 27 μm.

<Example 6>

A crude polyurethane product was obtained in a similar manner to Example 4. However, in this example, N ₂ gas was applied in an amount of 18% by volume based on the total volume of the crude polyurethane product to be formed, and the physical foaming agent was applied in an amount of 4% by weight based on the total weight of the crude polyurethane product to be formed. Approved as %.

Thereafter, the obtained crude polyurethane product was treated in the same manner as in Example 4 to prepare a polishing layer. The average pore size on the polished surface of the polishing layer was 24 μm.

<Example 7>

A crude polyurethane product was obtained in a similar manner to Example 4. However, in this example, N ₂ gas was applied in an amount of 20% by volume based on the total volume of the crude polyurethane product to be formed, and the physical foaming agent was applied in an amount of 2.0% by weight based on the total weight of the crude polyurethane product to be formed. Approved as %.

Thereafter, the obtained crude polyurethane product was treated in the same manner as in Example 4 to prepare a polishing layer. The average pore size on the polished surface of the polishing layer was 21 μm.

FIG. 4A is an image of a plurality of pores on the polished surface of the polishing layer obtained in Example 3, and FIG. 4B is an image of a plurality of pores on the polished surface of the polishing layer obtained in Example 4.

Comparing the images of FIGS. 4A and 4B, it can be seen that the average size of the plurality of pores on the polished surface of the polishing layer obtained in Example 4 is smaller and the size of the plurality of pores is more uniform.

Figure 5a is a view showing enlarged photographs comparing the states of the polished surface before the CMP process (PRE-CMP) and the polished surface after the CMP process (POST-CMP) using the polishing layer obtained in Example 3. , Figure 5b is a view showing enlarged photographs comparing the states of the polished surface before (PRE-CMP) and the polished surface after the CMP process (POST-CMP) using the polishing layer obtained in Example 4. am.

Comparing FIGS. 5A and 5B, in the case where polyurethane is formed by mixing polypropylene glycol with a functional group of 4 or more as in Example 4, the polishing layer is polished even after the CMP process compared to the case of Example 3. It can be confirmed that the shape of the open pores exposed from the surface is maintained well, and that no glazing phenomenon occurs in the open pores. Polishing performance needs to remain constant during the lifetime of the polishing layer in the CMP process. If a plurality of open pores exposed on the polishing surface of the polishing layer of the polishing pad are clogged and a glazing phenomenon occurs, polishing performance gradually deteriorates as the CMP process progresses, causing the problem that the usable time of the polishing pad is shortened. As illustrated in FIG. 5B, the shape of the open pores in the polishing layer obtained in Example 3 is continuously maintained, so that the polishing performance of the polishing pad can be kept constant without deterioration. Accordingly, the life time of the polishing pad can be increased and the replacement cost of the polishing pad can be reduced.

Figure 6 is a photograph of the polished surface of each polishing layer obtained according to Examples 4 to 7 before using it in a polishing process, and is a view showing the state of a plurality of open pores exposed on each polished surface.

Figure 7 shows that after preparing urethane prepolymers with various viscosities, an inert gas is applied to them in an amount of 5% by volume based on the total volume of the crude polyurethane product to be formed, and the boiling point is 60 ° C. as a physical foaming agent. The average pore size change in the polishing layer obtained as a result of manufacturing the polishing layer in a similar manner as in Example 4, except that 10% by weight was applied based on the total weight of the crude polyurethane product to form the phosphorus foaming agent. This is a graph showing the results evaluated according to the viscosity of the prepolymer.

From the results in Figure 7, it can be seen that when the viscosity of the urethane prepolymer is higher than 20,000 cps (25°C), pores of about 30 μm or less are formed. However, when the viscosity of the urethane prepolymer is more than 40,000 cps (25°C), there may be a problem that it is practically difficult to handle and control due to excessive viscosity. To prevent such problems, urethane prepolymer with a viscosity of 40,000 cps (25°C) or less can be used to manufacture the polishing layer.

Figure 8 is a graph evaluating the change in average pore size in the polishing layer according to the boiling point of the physical foaming agent.

For the evaluation of FIG. 8, the average pore size in the polishing layers obtained in a similar manner as in Example 4 was measured, except that physical foaming agents (A to E) having different boiling points were used, and the average pore size was measured according to the boiling point of the physical foaming agent. The average pore size change was evaluated. In Figure 8, A is n-pentane (boiling point 36.1°C), B is PF-5056 (boiling point 60°C), C is PF-5058 (boiling point 80°C), D is C ₄ F ₉ NO (boiling point 95°C), E is methyl cellosolve (boiling point 124°C), and F is cyclohexanone (boiling point 154°C).

From the results of FIG. 8, when the boiling point of the foaming agent is about 60°C or higher, a plurality of pores having an average pore size of about 30 μm or less can be formed, and the average size of the plurality of pores formed in the polishing layer is up to about 21 μm. It can be seen that it can be reduced. If the boiling point of the foaming agent exceeds 150°C, the reaction time becomes significantly longer due to a decrease in the foaming rate, and the number of pores generated by foaming decreases, which may result in a decrease in the slurry collection efficiency of the polishing pad. To prevent such problems, a foaming agent having a boiling point of about 150°C or lower can be used as a physical foaming agent.

Figure 9 is a graph evaluating the change in average pore size of a plurality of pores formed in the polishing layer depending on the content of the inert gas and the content of the physical foaming agent.

In the evaluation of Figure 9, the content of the inert gas represents the volume percent based on the total volume of the crude polyurethane product obtained during the manufacturing process of the polishing layer, and the content of the physical foaming agent represents the crude polyurethane product obtained during the manufacturing process of the polishing layer. It represents weight percent based on the total weight.

From the results in FIG. 9, it can be seen that the average pore size of a plurality of pores formed in the polishing layer changes as the ratio of the inert gas and the low boiling point foaming agent changes. In particular, it can be seen that when the content of the inert gas is about 5% by volume or more and the content of the physical blowing agent is about 10% by weight or less, a plurality of pores having an average pore size of about 31 μm or less can be formed.

If the content of the inert gas exceeds 30% by volume, the specific gravity of the polishing pad may decrease and the polishing efficiency of the polishing pad may decrease. Therefore, the content of inert gas can be set to 30% by volume or less. When the content of the physical foaming agent is less than 0.1% by weight, the influence of the physical foaming agent is minimal, so it is difficult to form a plurality of uniformly and finely distributed pores, and pores with a size exceeding about 31 μm may be mainly formed. Therefore, the content of the physical foaming agent can be set to at least 0.1% by weight.

FIG. 10A is a graph evaluating the polishing rate of the tungsten (W) film when the tungsten (W) film was polished for about 1 hour using the polishing layers obtained in Examples 3 and 4, respectively, and FIG. 10B is a graph evaluating the polishing rate of the tungsten (W) film obtained in Examples 3 and 4, respectively. This is a graph evaluating the lifetime characteristics when polishing a tungsten film using a polishing layer.

FIG. 11A is a graph evaluating the polishing rate of the silicon oxide film when the silicon oxide film was polished for about 1 hour using the polishing layers obtained in Examples 3 and 4, respectively, and FIG. 11B is a graph evaluating the polishing rate of the silicon oxide film obtained in Examples 3 and 4, respectively. This is a graph evaluating the lifetime characteristics when polishing a silicon oxide film using layers.

From the results of FIGS. 10A to 11B, when the tungsten film and the silicon oxide film were respectively polished using a polishing layer prepared by mixing a physical foaming agent and an inert gas as in Example 4, the physical foaming agent and an inert gas were used as in Example 3. It can be seen that it exhibits excellent polishing characteristics and excellent lifetime characteristics compared to the case where only a medium inert gas is used.

Figure 12a shows the surface roughness on the polished surface of each polished layer after performing a CMP process using the polished layers obtained in Examples 3 and 4, respectively, as the average length (Rsm: mean width) of the roughness curve elements of the corresponding polished surface. This is a graph showing the results of evaluation using profile elements.

For the evaluation of FIG. 12A, a silicon oxide film was formed as a polishing stop film on the wafer, a tungsten film was formed on the polishing stop film, and then the polishing layer and the tungsten polishing slurry obtained in Examples 3 and 4 were used, respectively. A CMP process is performed on the tungsten film for about 1 hour, and the polishing stop film exposed as the tungsten film is removed by the CMP process is continuously performed using the polishing layer and the tungsten polishing slurry. After that, the surface roughness on the polished surface of each polishing layer was evaluated.

Figure 12b shows the results of evaluating the average size of polishing pad debris separated from the polishing surface of the polishing layer during the CMP process after performing a CMP process using the polishing layers obtained in Examples 3 and 4, respectively. This is a graph showing .

For the evaluation of Figure 12b, the surfaces of the polishing layers obtained in Examples 3 and 4 were conditioned using deionized water, and a CMP process was performed on the silicon oxide film on the wafer for about 1 hour. , the average size of the polishing pad debris separated from the polishing surface of each polishing layer during the CMP process was measured.

Figure 12c is a graph showing the results of evaluating the number of scratches formed on the surface of the film to be polished remaining on the wafer after performing the CMP process using the polishing layers obtained in Examples 3 and 4, respectively.

For the evaluation of FIG. 12C, a CMP process was performed for about 1 hour on the silicon oxide film formed on each of the 60 wafers using the polishing layers obtained in Examples 3 and 4, respectively, and then a CMP process was performed on the 60 wafers. The average value of the number of scratches formed on the polished surface of the remaining silicon oxide film was calculated.

From the results of FIGS. 12A to 12C, it can be seen that when the polishing layer obtained in Example 4 was used, the efficiency of the CMP process was more excellent than when the polishing layer obtained in Example 3 was used. In particular, as shown in the results of FIG. 12a, when the Rsm value obtained on the polished surface of the polishing layer is small after polishing using the polishing layer obtained in Example 4, as illustrated in FIG. 12b, wear of the polishing pad during the CMP process occurs. It can be seen that the size of the polishing pad debris generated by the polishing pad is reduced, and the number of scratches is also reduced on the polished surface of the polishing object, as illustrated in FIG. 12C.

As in Example 4, when each tungsten film is polished using a polishing layer prepared by mixing a physical foaming agent and an inert gas, the average size of the plurality of pores formed in the polishing layer is small and relatively uniform in size, so that there is a gap between the pores. The distance may be shortened. Therefore, compared to Example 3, where the polishing layer was manufactured using only an inert gas among the physical foaming agent and the inert gas, the Rsm value can be lowered to improve the surface roughness. Accordingly, as can be seen in FIGS. 12A to 12C, the result of increasing the efficiency of the CMP process can be obtained.

When manufacturing an integrated circuit device using a polishing pad manufactured by a method according to the embodiments of the present invention, the polishing slurry is collected in a relatively uniform and fine size during the CMP process to improve polishing performance and planarization performance. By maximizing it, the reliability of the CMP process can be improved in the manufacturing process of miniaturized integrated circuit devices, and the manufacturing cost of integrated circuit devices can be lowered by increasing the life time of the polishing pad and reducing polishing pad replacement costs. Accordingly, the productivity of integrated circuit devices can be improved by performing a CMP process using a polishing pad manufactured by the method according to the embodiments of the present invention.

Above, the present invention has been described in detail with preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications and changes can be made by those skilled in the art within the technical spirit and scope of the present invention. This is possible.

100: polishing pad, 110: support layer, 120: polishing layer, 122: polymer matrix, 126: pore, 126A: open pore, 128: polishing surface, 200: polishing device, 202: platen, 204: head.

Claims (20)

forming a urethane prepolymer,
reacting a urethane prepolymer and a curing agent to form a reactant;
sequentially applying a physical blowing agent and an inert gas to the reactants and mixing the reactants to form a crude polyurethane product;
vaporizing the physical foaming agent using reaction heat generated from the crude polyurethane product while suppressing vaporization of the physical foaming agent with the inert gas;
gelling the crude polyurethane product;
Curing the gelled crude polyurethane product to form a porous polyurethane polishing layer including a plurality of pores,
The physical foaming agent is characterized in that it consists of cyclohexanone, perfluoromorpholine compounds, Novec 1230 (perfluoro(2-methyl-3-pentanone: C ₆ F ₁₂ O), or a combination thereof. A method of manufacturing a polishing pad for manufacturing integrated circuit elements. According to paragraph 1,
In the step of forming the urethane prepolymer, the urethane prepolymer is formed to have a viscosity of 20,000 to 40,000 cps at 25°C. According to paragraph 1,
The step of forming the urethane prepolymer includes reacting a plurality of polyols having different structures with an isocyanate compound,
A method of manufacturing a polishing pad for manufacturing an integrated circuit device, wherein the plurality of polyols include at least one polyol having at least 4 -OH groups. According to paragraph 3,
A method of manufacturing a polishing pad for manufacturing an integrated circuit device, wherein the plurality of polyols each have a number average molecular weight (Mn) of 500 to 10,000. According to paragraph 3,
The plurality of polyols are polypropylene glycol, polyurethane, polyether, polyester, polysulfone, polyacrylic, polycarbonate, polyethylene, polymethyl methacrylate, polyvinyl acetate, polyvinyl chloride, polyethylene imine, and polyether sulfone. A method of manufacturing a polishing pad for manufacturing an integrated circuit device, characterized in that the polishing pad is selected from polyether imide, polyketone, melamine, nylon, and fluorohydrocarbon compounds. According to paragraph 1,
The step of forming the urethane prepolymer includes reacting a plurality of polyols having different structures with an isocyanate compound to form the urethane prepolymer having an unreacted -NCO group,
The step of forming the reactant includes reacting the unreacted -NCO group of the urethane prepolymer with the curing agent. According to paragraph 1,
A method of manufacturing a polishing pad for manufacturing an integrated circuit device, characterized in that the physical foaming agent has a boiling point of 60 to 150 ° C. delete delete According to paragraph 1,
A method of manufacturing a polishing pad for manufacturing an integrated circuit device, characterized in that the inert gas is made of He, Ne, Ar, Kr, Xe, Rn, N ₂ , or a combination thereof. According to paragraph 1,
The step of forming the crude polyurethane product is
mixing the physical foaming agent in liquid phase with the reactant to form a preliminary blend;
A method of manufacturing a polishing pad for manufacturing an integrated circuit device, comprising the step of mixing the preliminary blend while applying the inert gas to the preliminary blend. According to clause 11,
In the step of forming the preliminary blend, the physical foaming agent is applied to the reactant in an amount of 0.1 to 10% by weight based on the total weight of the crude polyurethane product. Method for producing a polishing pad for manufacturing an integrated circuit device, characterized in that . delete According to paragraph 1,
The step of forming the urethane prepolymer includes reacting a plurality of polyols having different structures with an isocyanate compound,
A method of manufacturing a polishing pad for manufacturing an integrated circuit device, wherein the plurality of polyols include at least one polyol having at least 4 -OH groups in an amount of 1 to 30% by weight based on the total weight of the urethane prepolymer. According to paragraph 1,
The step of forming the reactant includes forming a polyurethane with a three-dimensional network structure by cross-linking following a reaction between the urethane prepolymer and the curing agent. According to paragraph 1,
A method of manufacturing a polishing pad for manufacturing an integrated circuit device, further comprising processing the porous polyurethane polishing layer to form a polishing surface where a plurality of pores are exposed. forming a urethane prepolymer having a viscosity of 20,000 to 40,000 cps at 25°C;
forming a crude polyurethane product using the urethane prepolymer, a curing agent, a physical foaming agent having a boiling point of 60 to 150° C., and an inert gas;
vaporizing the physical foaming agent using reaction heat generated from the crude polyurethane product while suppressing vaporization of the physical foaming agent with the inert gas;
gelling the crude polyurethane product;
Curing the gelled crude polyurethane product to form a porous polyurethane polishing layer including a plurality of pores,
The physical foaming agent is characterized in that it consists of cyclohexanone, perfluoromorpholine compounds, Novec 1230 (perfluoro(2-methyl-3-pentanone: C ₆ F ₁₂ O), or a combination thereof. A method of manufacturing a polishing pad for manufacturing integrated circuit elements. According to clause 17,
The step of forming the urethane prepolymer is
Comprising the step of reacting a plurality of polyols having different structures with an isocyanate compound,
A method of manufacturing a polishing pad for manufacturing an integrated circuit device, wherein the plurality of polyols include at least one polyol having at least 4 -OH groups. delete According to clause 17,
A method of manufacturing a polishing pad for manufacturing an integrated circuit device, characterized in that the inert gas is made of He, Ne, Ar, Kr, Xe, Rn, N ₂ , or a combination thereof.

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