JP7139299B2 - Polishing pad, manufacturing method thereof, and polishing method using same - Google Patents

Description

Embodiments relate to a polishing pad that reduces the number of defects in a polished substrate, a method of manufacturing the same, and a method of polishing using the same.

Polishing pads are used in chemical mechanical planarization (CMP) to enable easy industrial fine surface processing, and are used in silicon wafers for semiconductor devices, memory disks, magnetic disks, and optical lenses. , optical materials such as reflective mirrors, glass plates, metals, and other materials that require a high degree of surface flatness.

With the miniaturization of semiconductor circuits, the importance of the CMP process is increasing. A CMP pad is one of the essential raw materials and auxiliary materials in the CMP process in the semiconductor manufacturing process, and plays an important role in realizing CMP performance.

Various performances are required for the CMP pad, and the number of defects in the material after planarization is a factor that greatly affects the yield, so it is very important to distinguish the merits and demerits of the CMP pad. can be said to be a factor.

Korean Patent No. 10-2016-0132882, Polishing Pad and Manufacturing Method thereof Korean Patent No. 10-0892924, polishing pad

SUMMARY OF THE INVENTION It is an object of embodiments to provide a polishing pad, a method of manufacturing the same, and a method of polishing using the same that reduce the number of defects on a polished substrate.

To achieve the above objects, a polishing pad according to an embodiment includes polyurethane, the polyurethane includes a silane-based repeating unit represented by the following chemical formula 1 in the main chain, and the polishing pad and a fumed silica slurry: It has low defect characteristics such that the number of defects on the polished substrate is 40 or less.

In Chemical Formula 1, R ₁₁ and R ₁₂ are each independently hydrogen or an alkyl group having 1-10 carbon atoms, and n is an integer of 1-30.

The polyurethane may include a repeating unit represented by the following chemical formula 2-1 or chemical formula 2-2 in its main chain.

In Chemical Formula 2-1 or Chemical Formula 2-2, R ₁₁ and R ₁₂ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ₂₁ is —Si(R ₁₃ )(R ₁₄ )(R ₂₂ )—, wherein R ₁₃ and R ₁₄ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ₂₂ is —(CH ₂ ) _m1 - or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 - (provided that m1, m2 and m3 are each independently an integer of 1 to 20), said n is 1 to 30 is an integer.

The polishing pad may have a contact angle difference value (Ad _(p−f) , %) of 1.5 to 5 according to Formula 1 below.

[Formula 1]
Ad _(p−f) = [100×(Ap−Af)]/Ap

In Equation 1, Ap is the contact angle measured with pure water, and Af is the contact angle measured with fumed silica slurry.

The polyurethane may be in foam form.

The foam may have an average pore size of 10-30 μm.

The polyurethane may have a Shore D hardness of 55-65.

The polishing pad may include a top pad and a sub-pad located on one side of the top pad.

The top pad can include the polyurethane.

The subpad may be a nonwoven or suede type material.

A polishing pad according to another embodiment includes a top pad, which is a polyurethane-based polishing layer, and includes a foam of the polyurethane-based urethane composition, wherein the urethane composition includes a urethane-based prepolymer and a curing agent. , and blowing agents.

The urethane-based prepolymer is a copolymer of a prepolymer composition, the prepolymer composition includes an isocyanate compound, an alcohol compound, and a silane-based compound, and the silane-based compound includes a silane-based repeating unit, and The silane-based repeating unit has a hydroxyl group, an amine group, or an epoxy group on at least one terminal, and is represented by Formula 1 above.

The silane-based compound may be included in an amount of 0.1-5% by weight based on the entire prepolymer composition.

The top pad can reduce the degree of defects of the polished silicon wafer by 80% or more compared to the foam-type polyurethane containing no silane-based repeating unit represented by Chemical Formula 1.

The silane-based compound may be a compound represented by Chemical Formula 3 below.

In Chemical Formula 3, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ₂₂ is —(CH ₂ ) _m1 — or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 - (where m1, m2, and m3 are each independently an integer of 1 to 20), and R ₃₁ has 1 to 20 carbon atoms; wherein R ₄₁ and R ₄₂ are each independently a hydroxy group, an amine group or an epoxy group, and n is an integer of 1-30.

The prepolymer may have an NCO % of 8-12% by weight.

A method of manufacturing a polishing pad according to yet another embodiment comprises: i) a polyurethane forming step of polymerizing a urethane composition to form a polyurethane in the form of a foam; ii) manufacturing a top pad comprising the polyurethane. and iii) a lamination process of bonding the top pad with a sub pad to produce a polishing pad.

The urethane composition includes a urethane prepolymer, a curing agent and a foaming agent, and the main chain of the polyurethane includes silane-based repeating units represented by Formula 1 above.

The urethane prepolymer may be produced by a method for producing a urethane prepolymer.

The method for producing the urethane prepolymer includes reacting a prepolymer composition containing an isocyanate compound, an alcohol compound and a silane compound at 50 to 120° C. to produce a urethane prepolymer having an NCO% of 8 to 12% by weight. a prepolymer manufacturing step of:

The silane-based compound includes the silane-based repeating unit of Formula 1, and at least one terminal thereof includes a hydroxyl group, an amine group, or an epoxy group.

The prepolymer manufacturing step includes a first process of mixing a first composition containing the isocyanate compound and the alcohol compound and reacting the first composition at 60 to 100° C. for 1 to 5 hours to form a first polymer; a second step of mixing a polymer and a second composition comprising the silane-based compound and reacting at 60-100° C. for 0.5-3 hours to form a second polymer;

A method of manufacturing a polished wafer according to yet another embodiment includes the steps of: preparing to mount the polishing pad and the wafer before polishing in a CMP polishing apparatus; a polishing step of polishing a wafer before polishing using the polishing pad to produce a polished wafer;

A polishing pad according to an embodiment, a method for manufacturing the same, and a polishing method using the same are capable of maintaining a polishing rate and a cutting rate at the same level as the conventional polishing pad, and manufacturing the polishing pad with a significantly reduced number of defects. A method and a method of polishing a wafer using the same can be provided.

1 is a conceptual diagram illustrating a cross section of a polishing pad including a top pad according to an embodiment; FIG. 1 is a result of electron microscopic observation of pores of top pads of Example 1(a), Example 2(b) and Comparative Example 1(c) manufactured in an embodiment. 4 is a graph comparing polishing rate (top) and cutting rate (bottom) of polishing pads manufactured according to an embodiment; 5 is a graph comparing results of measuring the number of defects (#defect) of silicon wafers polished using the polishing pad manufactured in the embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. Embodiments may, however, be embodied in many different forms and are not limited to the illustrative embodiments set forth herein.

As used herein, the terms "about," "substantially," etc., are defined at or near the numerical value when manufacturing and material tolerances inherent in the referenced meaning are presented. and to prevent unscrupulous infringers from exploiting disclosures in which exact or absolute numerical values are referred to to aid understanding of the invention.

Throughout this specification, the term "a combination thereof" included in a Markush-form expression means a mixture or combination of one or more selected from the group consisting of the components set forth in the Markush-form expression. comprising one or more selected from the group consisting of the aforementioned constituents.

Throughout this specification, references to "A and/or B" mean "A, B, or A and B."

Throughout this specification, terms such as "first", "second" or "A", "B" are used to distinguish the same terms from each other unless otherwise stated.

As used herein, B positioned on A means that B is positioned directly on A, or B is positioned on A with another layer positioned between them. , and is not to be construed as being limited to B being positioned abutting the surface of A.

In this specification, singular expressions are to be interpreted to include the singular or plural, as the context dictates, unless otherwise stated.

As used herein, defects refer to polishing defects such as micro-scratches or chatter marks.

A polishing pad used in the chemical mechanical polishing technology should polish the substrate quickly and accurately, and at the same time, polish the surface of the substrate free from scratches. The inventors have been researching methods for reducing the number of defects while maintaining other properties of the polishing pad at a comparable level or better, and discovered that the slurry solution contains A polishing pad having a high contact angle, however, has been manufactured and used to confirm that the number of defects on a polished wafer can be significantly reduced, thus completing the embodiment.

FIG. 1 is a conceptual diagram illustrating a cross section of a polishing pad according to an embodiment. 1, the polishing pad 100 includes polyurethane, and the polyurethane includes a silane-based repeating unit represented by Formula 1 below.

In Chemical Formula 1, R ₁₁ and R ₁₂ are each independently hydrogen or an alkyl group having 1-10 carbon atoms, and n is an integer of 1-30.

Specifically, in Formula 1, R ₁₁ and R ₁₂ may each independently be hydrogen or an alkyl group having 1 to 5 carbon atoms, and n may be an integer of 8 to 28. .

The polishing pad 100 can perform stable polishing during the chemical mechanical polishing process due to the influence of silane-based repeating units included in the main chain of polyurethane, and can reduce the occurrence of defects on the polished substrate. can. Especially when the polishing pad 100 is applied to fumed silica slurry, the effect of suppressing the generation of defects in the polished substrate is great.

The polyurethane may include a repeating unit represented by Formula 2-1 or Formula 2-2 below.

In Chemical Formula 2-1 or Chemical Formula 2-2, R ₁₁ and R ₁₂ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ₂₁ is —Si(R ₁₃ ). (R ₁₄ )(R ₂₂ )—, wherein R ₁₃ and R ₁₄ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ₂₂ is —(CH ₂ ) _m1 - or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 - (where m1, m2, and m3 are each independently an integer of 1 to 20), and said n is 1 to 30; is an integer.

Specifically, in Chemical Formula 2-1 or Chemical Formula 2-2, R ₁₁ and R ₁₂ are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms, and R ₂₁ is - Si(R ₁₃ )(R ₁₄ )(R ₂₂ )—, wherein R ₁₃ and R ₁₄ are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms, and R ₂₂ is — (CH ₂ ) _m1 — or —(CH ₂ ) _m2 — (OCH ₂ CH ₂ ) _m3 — (provided that m1, m2, and m3 are each independently an integer of 2 to 12), and said n is It is an integer from 8 to 28.

The polishing pad 100 may contain 0.1 to 5% by weight of the silane-based repeating unit represented by Chemical Formula 2-1 or Chemical Formula 2-2. In this case, it is possible to appropriately and efficiently suppress the phenomenon of the slurry particles sticking to the surface or pores of the polishing pad, which is intended in the embodiment.

Specifically, the chemical formula 2-1 or chemical formula 2-2 may be the following chemical formula 2-3 or 2-4, respectively.

In Formula 2-3 or 2-4, n is an integer of 8-28, and p is an integer of 1-10. Specifically, in Formula 2-3 or 2-4, n may be an integer of 10-25, and p may be an integer of 1-5.

The polyurethane having the above characteristics may be applied to the entire polishing pad 100 or to the top pad 10 in a polishing pad structure including the top pad 10 and the subpad 30 .

The polyurethane may be in the form of a foam.

The foam-type polyurethane may be produced by mixing a foaming agent into the composition during the production of the polyurethane. The foaming agent may be formed by mixing any one foaming agent selected from the group consisting of a gas phase foaming agent, a solid phase foaming agent, a liquid phase foaming agent and a combination thereof.

The polishing pad 100 can reduce the number of defects on the polished silicon oxide film by applying the polishing pad 100 including the top pad 10 and a fumed silica slurry. The number of reduced defects may be 40 or less, 25 or less, 10 or less, or 0 or more. The substrate may be disc-shaped with a diameter of about 300 mm or more. The substrate can have a surface area of about 70685.83 mm ² or greater. The number of defects is based on the surface area measurement.

The defects are the result of cleaning and drying the silicon wafer polished using the CMP polishing equipment and evaluating it using a defect measurement equipment (manufacturer: Tencor, model name: XP+).

The polishing was carried out by placing a 300 mm silicon wafer on which silicon oxide was deposited in a CMP polishing apparatus, and placing the silicon oxide layer of the silicon wafer in contact with the surface plate to which the polishing pad 100 was attached. After that, it was polished while being rotated at a polishing load of 4.0 psi and 150 rpm for 60 seconds. At this time, the slurry can be applied, for example, fumed silica slurry or ceria slurry.

Specifically, the fumed silica slurry may be a slurry having a pH of 10.5 and 12% by weight of fumed silica having an average particle size of 150 nm dispersed therein.

KLA-Tencor
Specifically, the fumed silica slurry can be produced by the following method.

A base solution, which is a pH 10.5 solution containing the first pH adjuster and ultrapure water, is prepared. At this time, ammonia, potassium hydroxide, sodium hydroxide, etc. may be applied as the first pH adjuster. 12% by weight of fumed silica (manufactured by OCI) was added to the base solution by adding little by little while mixing at a speed of 9000 rpm using an ultra sonicator to disperse silica. Prepare the base solution. After about 4 hours of dispersion, additional dispersion was performed using a high-pressure disperser, 0.5-2% by weight of an ammonium-based additive was added, and additional stirring was performed for 1 hour. After that, 0.01 to 0.1% by weight of a nonionic surfactant (eg, polyethylene glycol) and a second pH adjuster are added to prepare a mixed slurry solution of pH 10.5. Ammonia, potassium hydroxide, sodium hydroxide, nitric acid, sulfonic acid, etc. can be used as the second pH adjuster. The mixed slurry solution was filtered by applying a slurry filter (manufactured by Micropore Co., Ltd.) having pore sizes of 3.5 μm and 1 μm to obtain a final fumed silica slurry. The final fumed silica slurry had a pH of 10.5 and dispersed 12% by weight of fumed silica with an average particle size of 150 nm (measurement: nano-ZS 90, Malvern). The slurry thus produced is then applied as the fumed silica slurry standard solution when measuring contact angles.

When the polishing pad 100 is applied at a cutting rate of 45 to 55 μm/hr, the number of silicon wafer defects is 40 or less, and the number of defects is 25 or less. , or 10 or less.

When the polishing pad 100 is applied at a polishing rate of 2600 to 2900 Å/min, the number of silicon wafer defects is 40 or less, and the number of defects is 25 or less. , or 10 or less.

The polishing pad 100 may have a contact angle difference value (Ad _(p−f) , %) of 1.5 to 5, preferably 2 to 4, according to Formula 1 below. may be

[Formula 1]
Ad _(p−f) = [100×(Ap−Af)]/Ap

In the formula 1, the Ap is the contact angle measured with pure water, the Af is the contact angle measured with the fumed silica slurry, and Ad _(pf) is the formula 1 is the contact angle difference value.

When the difference value of the contact angle has the above value, when polishing the substrate by applying the fumed silica slurry, the cutting rate, polishing rate, etc. are maintained at substantially the same or higher level than in the existing case, The degree of defects can be significantly reduced.

The contact angle measurements are performed at room temperature. The fumed silica slurry has a pH of 10.5 and is based on 12% by weight dispersion of fumed silica with an average particle size of 150 nm. Further, since the specific composition and manufacturing method of the fumed silica slurry, which is the standard for measuring the contact angle, overlaps with the above description, the description thereof is omitted.

The contact angle measured with the fumed silica slurry of the polishing pad 100 may be 85-120°.

The polishing pad 100 may have a contact angle of 85 to 125 degrees with respect to pure water.

In the polishing pad 100, the difference between the contact angle with respect to pure water and the contact angle measured with the fumed silica slurry may be 1.5° or more, 1.8° or more, or 2°. or more.

In the polishing pad 100, the difference between the contact angle to pure water and the contact angle measured with the fumed silica slurry may be 1.2 to 5°, or 1.5 to 4°.

As described above, the polishing pad 100 having a relatively large difference between the contact angle with respect to pure water and the contact angle with respect to fumed silica slurry has a repulsive force between the surface of the polishing pad and the slurry particles when in contact with the polishing slurry. can grow. Therefore, the phenomenon of slurry particles sticking on the surface or pores of the polishing pad can be significantly reduced, which makes it possible to obtain excellent polishing quality.

The polishing pad 100 having a relatively large difference between the contact angle for pure water and the contact angle for slurry has a greater effect of reducing defects when it is a foam pad. This is because the particles contained in the slurry may flow into and adhere to fine pores located on the surface of the foamed polishing pad, and in this case, defects may occur on the surface of the polished substrate. be. Since the configuration of the embodiment can significantly reduce such phenomena, it is believed that the defect reduction effect is great.

The polishing pad 100 includes silane-based repeating units on the main chain of polyurethane to induce greater repulsive force between the silica particles and the surface of the polyurethane. Through this, the polishing pad can significantly reduce the degree of defect generation while maintaining the polishing rate and cutting rate of the polishing pad using the slurry at substantially the same level or higher.

The polishing pad 100 includes a top pad 10 , a first adhesive layer 15 located on one side of the top pad, and a sub pad 30 located on one side of the first adhesive layer 15 .

The top pad 10 may be made of polyurethane in foam form having the characteristics described above. The top pad may be a foam with an average pore size of 10-30 mm. Applying a top pad having such an average pore size is good for improving the polishing efficiency of the polishing pad.

The top pad 10 may be polyurethane in the form of a foam with an area ratio of 36-44%. The top pad 10 may be a polyurethane foam having 350-500 pores per unit area. When the polyurethane top pad 10 in foam form with such characteristics is applied, efficient wafer polishing is possible.

The top pad 10 may have a Shore D hardness of 55 to 65, in which case polishing efficiency can be improved.

The top pad 10 may have a thickness of 1.5-3 mm, in which case polishing efficiency can be enhanced.

The sub pad 30 may have an Asker C hardness of 60-90.

The subpad 30 may be of non-woven fabric type or suede type.

The sub-pad 30 may have a thickness of 0.5-1 mm.

The top pad 10 and the subpad 30 can be attached via a hot melt adhesive layer 15 .

A rubber-based adhesive 35 (second adhesive layer) may be applied to the other surface of the sub-pad 30 .

A second adhesive layer of rubber-based adhesive 35 positioned on the other surface of the sub pad 30 may have a film 50 such as a PET film positioned on the other surface of the second adhesive layer. A rubber-based adhesive layer 55 (third adhesive layer) may be positioned on the film 50 .

The other surface of the sub-pad 30 can be adhered to the surface plate of the polishing machine via a rubber-based adhesive 35 (second adhesive layer).

A polishing pad 100 according to another embodiment includes a top pad 10 that is a polyurethane-based polishing layer.

The polyurethane-based polishing layer includes a foamed urethane composition containing a urethane-based prepolymer, a curing agent, and a foaming agent.

The urethane-based prepolymer is a copolymer of a prepolymer composition containing an isocyanate compound, an alcohol compound, and a compound containing a silane-based repeating unit.

As the silane-based compound, a compound capable of reacting with isocyanate to introduce a silane-based repeating unit into the main chain of urethane, such as silane-modified polyol and silane-modified amine, is applied.

Specifically, the silane-based compound may be a silane-based compound including a silane-based repeating unit represented by Chemical Formula 1 below and having at least one end of a hydroxyl group, an amine group, or an epoxy group.

Detailed descriptions of R ₁₁ , R ₁₂ , n, etc. in Chemical Formula 1 are the same as those described above, so descriptions thereof will be omitted.

The silane-based compound may be included in an amount of 0.1-5% by weight based on the entire prepolymer composition. The silane-based compound may be included in an amount of 1-3% by weight, or 1.5-2.5% by weight, based on the entire prepolymer composition.

When the silane-based compound is contained in an amount of less than 0.1% by weight based on the entire prepolymer composition, the defect reduction effect due to the inclusion of the silane-based compound is slight, and when it is contained in an amount exceeding 5% by weight However, gelation occurs during the synthesis process, and it is sometimes difficult to progress the synthesis so as to have the intended physical properties. When the silane-based compound is contained in the above amount, it is possible to provide a polyurethane polishing pad having an excellent effect of reducing defects.

Specifically, the top pad 10 reduces the degree of defects of the polished silicon wafer by 80% or more compared to the polyurethane foam that does not contain the silane-based repeating unit represented by Formula 1. or can be reduced by 85% or more. In addition, the top pad 10 can reduce the degree of defects of the polished silicon wafer by 90% or more compared to the polyurethane foam that does not contain the silane-based repeating unit represented by Chemical Formula 1. .

The degree of defect reduction is equivalent to the existing cutting rate, polishing rate, etc., and can significantly reduce the defect rate of silicon wafers due to defects.

The silane-based compound may be a compound represented by Chemical Formula 3 below.

In Chemical Formula 3, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ₂₂ is —(CH ₂ ) _m1 — or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 - (provided that m1, m2 and m3 are each independently an integer of 1 to 20), and R ₃₁ has 1 to 20 carbon atoms; an alkylene group, R ₄₁ and R ₄₂ are each independently a hydroxy group, an amine group, or an epoxy group; n is an integer of 1-30;

Specifically, in Chemical Formula 3, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms, and R ₂₂ is -( CH ₂ ) _m1 — or —(CH ₂ ) _m2 —(OCH ₂ CH ₂ ) _m3 — (provided that m1, m2, and m3 are each independently an integer of 2 to 12), and R ₃₁ is It is an alkylene group having 1 to 10 carbon atoms, R ₄₁ and R ₄₂ are each independently a hydroxy group, an amine group or an epoxy group, and n is an integer of 8 to 28.

More specifically, in Formula 3, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen, a methyl group, or an ethyl group, and R ₂₂ is —(CH ₂ ) _m1 - or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 - (provided that m1, m2, and m3 are each independently an integer of 2 to 12), and the R ₃₁ has a carbon number It is an alkylene group of 1 to 5, R ₄₁ and R ₄₂ are each independently a hydroxy group, an amine group or an epoxy group, and n is an integer of 10 to 25.

The isocyanate compound is selected from the group consisting of p-phenylene diisocyanate, 1,6-hexamethylene diisocyanate, toluene diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, 4,4-diphenylmethane diisocyanate, cyclohexylmethane diisocyanate and combinations thereof. any one of the above may apply, but is not limited thereto.

The alcohol compound may include one or more polyol compounds or monomolecular alcohol compounds.

The polyol compound may be any one selected from the group consisting of polyester polyol, polyether polyol, polycarbonate polyol, polycaprolactone polyol, and combinations thereof, but is not limited thereto.

The monomolecular alcohol compound may be any one selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, methylpropanediol, and combinations thereof, but is limited thereto. is not.

The urethane-based prepolymer may be a copolymer of the isocyanate compound, the alcohol compound, and the silane-based compound.

The prepolymer composition may contain 0.7 to 1.3 parts by weight of the alcohol compound and 0.05 to 7 parts by weight of the silane compound based on 1 part by weight of the isocyanate compound. can.

Specifically, the prepolymer composition may contain 0.8 to 1.2 parts by weight of the alcohol compound and 0.1 to 5 parts by weight of the silane compound based on 1 part by weight of the isocyanate compound. parts by weight.

More specifically, the prepolymer composition may contain 0.85 to 1.15 parts by weight of the alcohol compound and 1.6 to 1.6 parts by weight of the silane compound based on 1 part by weight of the isocyanate compound. 2.5 parts by weight.

When the prepolymer composition is composed within such a range, it is possible to produce a polyurethane having physical properties more suitable for a polishing pad.

The prepolymer may have an NCO % of 8-12% by weight. When the NCO % is within this range, a foam-type porous polyurethane pad having appropriate hardness can be produced.

The curing agent may be applied, for example, an amine curing agent.

Specifically, the amine curing agent is any one selected from the group consisting of 4,4′-methylenebis(2-chloroaniline), m-phenylenediamine, diethyltoluenediamine, hexamethylenediamine and combinations thereof. can be one.

The foaming agent may be a gas phase foaming agent, a solid phase foaming agent, a liquid phase foaming agent, or a combination thereof.

As the gas phase foaming agent, an inert gas can be specifically applied, for example, nitrogen gas, carbon dioxide gas, etc. may be applied.

Organic hollow spheres and/or inorganic hollow spheres can be applied as the solid-phase blowing agent, and for example, microspheres obtained by encapsulating a hydrocarbon gas with a polymer may be applied.

As the liquid foaming agent, a Galden solution (Triperfluoropropylamine), liquid carbon dioxide, liquid hydrofluorocarbon, etc. may be applied, but not limited thereto.

The urethane composition may further contain a surfactant. A nonionic surfactant or an ionic surfactant may be applied as the surfactant. Specifically, silicone surfactants such as copolymers containing at least one block containing polydimethylsiloxane and at least one other block containing polyether, polyester, polyamide, or polycarbonate segments. may apply, but is not limited to this.

The urethane composition contains 10 to 60 parts by weight of the curing agent, 0.1 to 10 parts by weight of the foaming agent, and 0.1 part of the surfactant based on 100 parts by weight of the urethane prepolymer. ~2 parts by weight.

Further, when a gas phase foaming agent is used as the foaming agent, the ejection speed can be applied at 0.1 to 2.0 L/min. When the urethane composition is composed in such a ratio, it is possible to form a foam-type polyurethane having physical properties suitable for a polishing pad.

A method for producing a urethane prepolymer for a polishing pad according to another embodiment includes an isocyanate compound, an alcohol compound, and a silane-based repeating unit represented by Chemical Formula 1, and at least one terminal thereof includes a hydroxyl group, an amine group, or an epoxy group. a prepolymer production step of reacting a prepolymer composition containing a silane-based compound at 50-120° C. to produce a urethane prepolymer having an NCO % of 8-12% by weight;

The prepolymer manufacturing step includes a first process of mixing a first composition containing the isocyanate compound and the alcohol compound and reacting the first composition at 60 to 100° C. for 1 to 5 hours to form a first polymer; a second step of mixing a polymer and a second composition comprising the silane-based compound and reacting at 60-100° C. for 0.5-3 hours to form a second polymer;

Specific descriptions of the isocyanate compound, the alcohol compound, the silane-based compound, the prepolymer composition, and the like overlap with the description above, and are therefore omitted.

In yet another embodiment of the method for manufacturing the polishing pad 100, i) the urethane composition is mixed and then polymerized to form a polyurethane foam containing silane-based repeating units represented by Formula 1 above. ii) a top pad manufacturing process for manufacturing a top pad 10 comprising said polyurethane; iii) a lamination process for bonding said top pad with a sub pad to manufacture a polishing pad; to manufacture a polyurethane polishing pad 100 containing the silane-based repeating unit represented by Formula 1 in the main chain.

The urethane composition contains a urethane prepolymer for polishing pads, a curing agent, and a foaming agent.

Specific descriptions of the isocyanate compound, the alcohol compound, the silane-based compound, the prepolymer composition, the urethane composition, etc. overlap with the above description, and are therefore omitted.

A method for manufacturing a polished wafer according to still another embodiment includes the preparation steps of mounting the polishing pad 100 and the wafer before polishing in a CMP polishing apparatus; and a polishing step of polishing the wafer before polishing using the polishing pad to manufacture a polished wafer.

The wafer before polishing may specifically be a silicon wafer, for example, a silicon wafer deposited with silicon oxide.

The polishing slurry may be a polishing slurry containing fumed silica, colloidal silica, ceria, or the like.

The polishing may be performed under pressure such that the wafer before polishing and/or the polishing pad are in contact with each other, and the pressure may be applied at 1-7 psi.

The polishing may be performed while rotating the wafer and/or the polishing pad before polishing, and the rotation speed may be 10 to 400 rpm.

The polishing can be performed for a polishing time of 1 to 10 minutes, and such polishing time can be adjusted as needed.

The polished wafer manufacturing method may further include a cleaning step after the polishing step.

The cleaning step includes separating the polished wafer from the CMP polishing apparatus and cleaning it with purified water and an inert gas (eg, nitrogen gas).

By applying the polishing pad of the embodiment, the method for manufacturing a polished wafer can manufacture a polishing pad having excellent polishing rate, cutting rate, etc., and at the same time, having a low number of defects.

Hereinafter, implementation examples will be described in more detail.

1. Manufacture of polishing pads

Production of top pad sheet of Example 1

TDI (Toluene Diisocyanate) as an isocyanate compound, and PTMEG (Polytetramethylene ether glycol) and diethylene glycol as a polyol compound were put into a four-necked flask and reacted at 80° C. for 3 hours to obtain a primary reactant. Obtained. The primary reactant and silane-modified polyol (Wacker (R) IM11, Mw: 1000) were placed in a four-necked flask and reacted at 80°C for 2 hours to form a prepolymer having an NCO% of 8 to 12% by weight. ) was manufactured. At this time, the silane-modified polyol was applied in an amount of 2% by weight based on the entire prepolymer.

In a casting machine equipped with a prepolymer tank, a curing agent tank, and an inert gas injection line, the prepolymer tank is filled with the prepolymer produced above, and screws (4- Amino-3-chlorophenyl)methane [Bis(4-amino-3-chlorophenyl)methane, manufactured by Ishihara] was charged. Nitrogen gas (N ₂ ) was prepared as the inert gas. A solid phase blowing agent (manufactured by Akzonobel) and a silicone-based surfactant (manufactured by Evonik) were mixed through a separate line or mixed with the prepolymer before application.

In the casting machine thus prepared, the equivalent ratio of prepolymer and curing agent was adjusted to 1:1, and casting was carried out while extruding at a rate of 10 kg per minute. At this time, the amount of nitrogen (N ₂ ), which is an inert gas, was injected at a rate shown in Table 1 below with respect to the volume of the total flow rate.

After mixing each raw material injected at high speed with a mixing head, it is injected into a mold of 1000 mm wide, 1000 mm long, and 3 mm high by adjusting the injection amount of inert gas, and the specific gravity is 0.8 to 0.9 g. /cc and the top pad sheet 10 of Example 1 having pores was obtained.

Production of top pad sheet of Example 2

TDI (Toluene Diisocyanate) as an isocyanate compound, and PTMEG (Polytetramethylene ether glycol) and diethylene glycol as a polyol compound were added to a four-necked flask and reacted at 80° C. for 3 hours to obtain a primary reaction product. rice field. The primary reactant and silane-modified polyol (Wacker (R) IM22, Mw: 2000) were placed in a four-necked flask and reacted at 80°C for 2 hours to obtain a prepolymer having an NCO% of 8 to 12% by weight. ) was manufactured. At this time, the silane-modified polyol was applied in an amount of 2% by weight based on the entire prepolymer.

A top pad sheet 10 of Example 2 was produced in the same manner as in Example 1, except that the prepolymer produced in Example 2 was used.

Production of sheet for top pad of Comparative Example 1

TDI (Toluene Diisocyanate) as an isocyanate compound, and PTMEG (Polytetramethylene ether glycol) and diethylene glycol as a polyol compound were put into a four-necked flask and reacted at 80° C. to obtain an NCO% of 8 to 12 wt. %, was prepared and subjected to the following process.

A top pad sheet of Comparative Example 1 was produced in the same manner as in Example 1, except that the prepolymer produced in Comparative Example 1 was used.

Manufacture of polishing pads

The top pad sheet 10 manufactured as described above was sequentially subjected to surface milling and grooving processes in a conventional manner, and laminated to the sub-pad 30, thereby manufacturing the polishing pad 100 having the structure shown in FIG.

2. Evaluation of physical properties of polishing pads

Evaluation of strength and contact angle

Using the polishing pads of Example 1, Example 2, and Comparative Example 1 manufactured above, the contact angle to fumed silica slurry was measured, the CMP polishing performance was evaluated, and the number of defects in the wafer was measured. Physical property evaluation such as measurement was performed.

The contact angle was obtained by sampling the central portion of the manufactured polishing pad with no groove in a width of 2 x 2 cm, and measuring this sample with a contact angle analyzer (Dynamic Contact Angle Analyzer, model name: DCA-312). , manufacturer: CAHN) was used to measure the contact angle.

After the specimens of Examples 1 and 2 and Comparative Example were mounted on the measuring machine, the syringes were filled with pure water (H ₂ O) and fumed silica slurry, and then tested. An appropriate amount was injected onto the test piece, and the shape of the water droplet placed on the test piece was evaluated by measuring the shape using a contact angle measuring device. The composition and manufacturing process of the fumed silica slurry will be described in a separate section.

Production of fumed silica slurry

A first pH adjusting agent (ammonia, potassium hydroxide, sodium hydroxide, etc.) and a pH 10.5 solution consisting of ultrapure water were prepared. About 12% by weight of fumed silica (manufactured by OCI) was dispersed using an ultra sonicator at a speed of 9000 rpm while adding little by little. After about 4 hours of dispersing, additional dispersing work was done through a high pressure disperser.

After a sufficient dispersion process, 0.5-2% by weight of an ammonium-based additive was added and further stirred for 1 hour. Then add 0.01 to 0.1% by weight of a nonionic surfactant, and use a second pH adjuster (ammonia, potassium hydroxide, sodium hydroxide, nitric acid, sulfonic acid, etc.) to adjust the pH of the solution. was adjusted to a level of 10.5.

The final fumed silica slurry was obtained by filtration using a slurry filter (micropore) with pore sizes of 3.5 μm and 1 μm. The physical properties of the final slurry are pH 10.5 and average particle size 150 nm (nano-ZS 90, manufactured by Malvern).

The physical properties of the top pad prepared above and the physical properties of the entire subpad and polishing pad are also shown in Table 2 below.

* The contact angle difference value (Ad _(pf) , %) is a value calculated by Ad _(pf) = [100 × (Ap-Af)] / Ap, where Ap is pure water (pure water), and Af is the contact angle measured with a fumed silica slurry. Measurements are taken at the same room temperature.

Referring to the results of Table 2, Comparative Example 1 and Examples 1 and 2 have almost the same characteristics such as hardness, average pore size, and specific gravity. It was confirmed that there is a considerable difference in the contact angle to silica slurry).

Physical property evaluation of top pad pores

The pores of the top pad were photographed at 100× by SEM (manufactured by JEOL), and then measured for number, size, area ratio, etc. The results are shown in FIG. 2 and Table 3 below.

Evaluation of polishing properties

Using the polishing pads of Example 1, Example 2, and Comparative Example 1 manufactured above, the removal rate, the pad cut-rate (μm/hr), and the thickness of the polished wafer Defects were measured by the following method.

1) Measurement of polishing rate

Using CMP polishing equipment, a silicon wafer with a diameter of 300 mm on which silicon oxide is deposited by a CVD process is installed, and then the porous polyurethane polishing pad is attached with the silicon oxide layer of the silicon wafer facing down. It was set on the surface plate. After that, the polishing load was adjusted to 4.0 psi, and while rotating the polishing pad at 150 rpm, the calcined ceria slurry was added onto the polishing pad at a rate of 250 ml/min, and the platen was rotated at 150 rpm for 60 seconds. The silicon oxide film was polished by rotating. After polishing, the silicon wafer was removed from the carrier, mounted in a spin dryer, washed with DIW, and dried with nitrogen for 15 seconds. A change in film thickness of the dried silicon wafer before and after polishing was measured using an optical interference thickness measuring device (manufacturer: Kyence, model name: SI-F80R).

The polish rate was calculated using Equation 2 below.

[Formula 2]
Polishing rate = polishing thickness of silicon wafer (Å) / polishing time (60 seconds)

2) Measurement of cutting rate

Each of the manufactured polishing pads was preconditioned with deionized water for an initial period of 10 minutes and then conditioned with deionized water spray for 1 hour. At this time, the change in thickness was measured during one hour of conditioning.

The equipment used for conditioning is CTS AP-300HM, the conditioning pressure is 6 lbf, the rotation speed is 100-110 rpm, and the disk used for conditioning is LPX-DS2 manufactured by Sesol Diamond Industry Co., Ltd. there were.

3) Defect measurement

Using CMP polishing equipment, polishing was performed in the same manner as in the method for measuring the polishing rate in 1) above.

After polishing, the silicon wafer was moved to a cleaner and cleaned for 10 seconds each using 1 wt % HF and purified water (DIW), 1 wt % H ₂ NO ₃ and purified water (DIW). Then, it was moved to a spin dryer, washed with purified water (DIW), and dried with nitrogen for 15 seconds.

The change in defects of the dried silicon wafer before and after polishing was measured using a defect measurement device (manufacturer: Tencor, model name: XP+).

The measurement results of polishing rate, cutting rate and number of defects (based on the surface of a disc-shaped wafer with a diameter of about 300 mm) are shown in Table 4, FIGS. 3 and 4 below.

* Defect reduction rate (%) is a value obtained by calculating "[(number of defects in comparative example−number of defects in example)×100]/number of defects in comparative example".

Referring to the measurement results, it was confirmed that the polishing pads of Examples 1 and 2 had similar polishing rates and cutting rates to those of the comparative example, and significantly reduced the number of defects in the polished wafers. .

Although the embodiments have been described in detail above, the scope of the invention is not limited thereto, and various modifications can be made by those skilled in the art using the basic concept of the embodiments defined in the appended claims. Any variations and modifications are also within the scope of the present invention.

REFERENCE SIGNS LIST 100 polishing pad 10 top pad, polishing layer 15 first adhesive layer 30 bottom pad, subpad 35 second adhesive layer 50 film 55 third adhesive layer

Claims (13)

A polishing pad comprising polyurethane,
The polyurethane includes a silane-based repeating unit represented by the following chemical formula 1 in the main chain,
The polishing pad has a contact angle difference value (Ad _(p−f) , %) of 1.5 to 5 according to the following formula 1.

In the chemical formula 1,
R ₁₁ and R ₁₂ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms,
The n is an integer of 1 to 30 ,
[Formula 1]
Ad _(p−f) = [100×(Ap−Af)]/Ap
In the above formula 1,
The Ap is the contact angle measured with pure water,
The Af is the contact angle measured with the fumed silica slurry . 2. The polishing pad of claim 1, wherein said polyurethane is in foam form, and said foam has an average pore size of 10-30 μm. The polishing pad according to claim 1, wherein the polyurethane has a Shore D hardness of 55-65. including a top pad and a sub-pad located on one surface of the top pad;
the top pad comprises the polyurethane;
2. The polishing pad of claim 1, wherein said subpad is of non-woven or suede type. A top pad, which is a polyurethane polishing layer containing a foam of a urethane composition containing a urethane prepolymer, a curing agent, and a foaming agent,
The urethane-based prepolymer is a copolymer of a prepolymer composition,
The prepolymer composition contains an isocyanate compound, an alcohol compound and a silane compound,
The silane-based compound includes a silane-based repeating unit and a hydroxyl group, an amine group, or an epoxy group at least at one end,
The polishing pad, wherein the silane-based repeating unit is represented by Chemical Formula 1 below.

In the chemical formula 1,
R ₁₁ and R ₁₂ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms,
Said n is an integer of 1-30. 6. The polishing pad according to claim 5, wherein the silane compound is contained in an amount of 0.1-5% by weight based on the entire prepolymer composition. 6. The top pad according to claim 5, wherein the top pad reduces the degree of defects of the polished silicon wafer by 80% or more compared to the foam-type polyurethane containing no silane-based repeating unit represented by Chemical Formula 1. polishing pad. 6. The polishing pad according to claim 5, wherein the silane-based compound is a compound represented by Chemical Formula 3 below.

In the chemical formula 3,
R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms,
R ₂₂ is -(CH ₂ ) _m1 - or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 - (provided that m1, m2 and m3 are each independently an integer of 1 to 20); ,
R ₃₁ is an alkylene group having 1 to 20 carbon atoms,
R ₄₁ and R ₄₂ are each independently a hydroxy group, an amine group, or an epoxy group;
Said n is an integer of 1-30. 6. The polishing pad of claim 5, wherein the prepolymer has an NCO % of 8-12 wt%. i) a polyurethane forming process in which the urethane composition is polymerized to form a polyurethane in foam form;
ii) a top pad manufacturing process for manufacturing a top pad comprising said polyurethane;
iii) a lamination step of fixing the top pad to a sub pad to produce a polishing pad;
The urethane composition contains a urethane prepolymer, a curing agent and a foaming agent,
A method for producing a polishing pad, wherein the main chain of the polyurethane includes a silane-based repeating unit represented by Chemical Formula 1 below.

In the chemical formula 1,
R ₁₁ and R ₁₂ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms,
Said n is an integer of 1-30. The urethane prepolymer is produced by a method for producing a urethane prepolymer,
The method for producing the urethane prepolymer includes reacting a prepolymer composition containing an isocyanate compound, an alcohol compound and a silane compound at 50 to 120° C. to produce a urethane prepolymer having an NCO% of 8 to 12% by weight. a prepolymer manufacturing step for
The method for manufacturing a polishing pad according to claim 10 , wherein the silane-based compound includes the silane-based repeating unit of Formula 1, and at least one terminal thereof includes a hydroxyl group, an amine group, or an epoxy group. The step of producing the urethane prepolymer includes a first step of mixing a first composition containing the isocyanate compound and the alcohol compound and reacting the first composition at 60 to 100° C. for 1 to 5 hours to form a first polymer;
and a second step of mixing the first polymer and the second composition containing the silane - based compound and reacting at 60-100° C. for 0.5-3 hours to form a second polymer. 12. The method for producing a polishing pad according to 11 . A preparation step of mounting the polishing pad according to claim 1 and a wafer before polishing to a CMP polishing apparatus, and polishing the wafer before polishing using the polishing pad while supplying polishing slurry to the CMP polishing apparatus. to produce a polished wafer.

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