TW202112916A - Polishing pad, preparation method thereof, and polishing method applying the same - Google Patents

Abstract

The present invention relates to a polishing pad, a method for manufacturing the polishing pad, and a polishing method using the polishing pad, wherein the number of defects on a substrate after polishing with the polishing pad and a fumed silica slurry is about 40 or less.

Description

Grinding pad, preparation method thereof, and grinding method using the same

The present invention relates to a polishing pad that reduces the number of defects of a polishing substrate, a manufacturing method of the polishing pad, and a polishing method using the polishing pad.

The polishing pad is used for chemical mechanical polishing (Chemical Mechanical Planarization, CMP). It is easy to perform surface micro-processing in industry. It can be widely used in silicon wafers for semiconductor equipment, memory disks, magnetic sheets, optical materials such as optical lenses or mirrors, etc. Flattening processing of materials that require high surface flatness, such as glass plates and metals.

With the miniaturization of semiconductor circuits, the importance of the CMP process has become more apparent. The CMP pad is one of the indispensable raw materials in the CMP process of the semiconductor manufacturing process, and it plays an important role in the realization of CMP performance.

CMP pads need to have various properties, but the number of defects (Defect) of the material after the planarization process is a factor that has a great influence on the yield of the material, so it can be considered as an extremely important factor to distinguish the quality of the CMP pad.

[Prior Technical Document] [Patent Literature] Domestic Patent Publication No. 10-2016-0132882, Polishing pad and manufacturing method thereof Domestic authorized patent No. 10-0892924, polishing pad

[technical problem] The object of the present invention is to provide a polishing pad that reduces the number of defects of a polishing substrate, a method for manufacturing the polishing pad, and a polishing method using the polishing pad.

在化學式1中，R₁₁ 及R₁₂ 各自獨立地為氫或C₁ -C₁₀ 烷基，n為1至30的整數。[Technical Solution] In order to achieve the above-mentioned object, the polishing pad according to the embodiment contains polyurethane, and the polyurethane contains a silane-based repeating unit represented by the following chemical formula 1 in its main chain, through the polishing pad and gas-phase dioxide The substrate polished by the silicon slurry has a low defect characteristic of less than 40 defects: [Chemical formula 1]

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

[化學式2-2]

The polyurethane may contain a repeating unit represented by the following Chemical Formula 2-1 or Chemical Formula 2-2 in its main chain: [Chemical Formula 2-1]

[Chemical formula 2-2]

In Chemical Formula 2-1 or Chemical Formula 2-2, R ₁₁ and the R ₁₂ are each independently hydrogen or a C ₁ -C ₁₀ alkyl group, and R ₂₁ is -Si(R ₁₃ )(R ₁₄ )(R ₂₂ ) , R ₁₃ and R ₁₄ are each independently hydrogen or C ₁ -C ₁₀ alkyl, R ₂₂ is -(CH ₂ ) _m1 -or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 (wherein, m1, m2 and m3 are each independently an integer from 1 to 20), and n is an integer from 1 to 30.

In Chemical Formula 2-1 or Chemical Formula 2-2, R ₁₁ and R ₁₂ are each independently hydrogen or C ₁ -C ₁₀ alkyl, R ₂₁ is -Si(R ₁₃ )(R ₁₄ )(R ₂₂ ), R ₁₃ and R ₁₄ are each independently hydrogen or C ₁ -C ₁₀ alkyl, R ₂₂ is -(CH ₂ ) _m1 -or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 (where m1, m2 and m3 is each independently an integer from 1 to 20), and n is an integer from 1 to 30.

The contact angle difference of the polishing pad according to the following equation 1 is 1.5 to 5: [Equation 1] Ad _(pf)= [100×(Ap-Af)]/Ap

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

The polyurethane may be in the form of a foam.

The average pore size of the foam may be 10 to 30 micrometers (μm).

The Shore D hardness of the polyurethane may be 55 to 65.

The polishing pad may include a top pad and a sub-pad provided on the top pad.

The top pad may include the polyurethane.

The sub-pad may be a non-woven fabric or suede type material.

A polishing pad according to another embodiment includes a top pad as a polyurethane polishing layer, the polyurethane polishing layer including a foam containing an urethane composition, the urethane composition containing an amine Ethyl formate prepolymer, curing agent and foaming agent.

The urethane prepolymer is a copolymer of a prepolymer composition. The prepolymer composition includes an isocyanate compound, an alcohol compound, and a silane compound. The silane compound contains a silane repeating unit and is At least one terminal contains a hydroxyl group, an amino group or an epoxy group.

Based on the entire prepolymer composition, the content of the silane compound may be 0.1 to 5% by weight.

Compared with polyurethane in the foam form without the silane-based repeating unit represented by Chemical Formula 1, the top pad can reduce the degree of defects of the polished silicon wafer by more than 80%.

The silane-based compound may be a compound represented by the following Chemical Formula 3: [Chemical Formula 3]

In Chemical Formula 3, R _{11 ,} R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen or C ₁ -C ₁₀ alkyl, and R ₂₂ is -(CH ₂ ) _m1 -or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 (wherein m1, m2 and m3 are each independently an integer from 1 to 20), R ₃₁ is a C ₁ -C ₂₀ alkylene group, and R ₄₁ and R ₄₂ are each independently a hydroxyl group, an amino group or Epoxy group, n is an integer of 1-30.

The NCO% of the prepolymer may be 8 to 12% by weight.

According to another embodiment, a method for manufacturing a polishing pad includes: a polyurethane forming process, forming a polyurethane in the form of a foam through a polymerized urethane composition; and a lamination process, combining the top pad with a sub pad (sub pad) ) Bonding to make a polishing pad.

The urethane composition contains urethane, a curing agent, and a foaming agent, and the main chain of the polyurethane contains a silane-based repeating unit represented by Chemical Formula 1.

The urethane prepolymer can be prepared through the preparation method of the urethane prepolymer.

The preparation method of the urethane prepolymer includes a prepolymer preparation step. In the prepolymer preparation step, the prepolymer composition is reacted at 50 to 120° C. to prepare NCO weight% 8 to 12% of urethane, wherein the prepolymer composition contains isocyanate compounds, alcohol compounds and silane compounds.

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

The preparation step of the prepolymer includes: a first process, mixing the isocyanate compound and the alcohol compound to prepare a first composition, and reacting at 60 to 100° C. for 1 to 5 hours to form the first polymer; and The second process is to mix the first polymer and the silane compound to prepare a second composition, and react at 60 to 100° C. for 0.5 to 3 hours to form a second polymer.

A method for manufacturing a polished wafer according to another embodiment includes: a preparation step of installing the previously described polishing pad and unpolished wafer in a CMP polisher; and a polishing step of injecting polishing slurry into the CMP polisher while using The polishing pad polishes the unpolished wafer, thereby manufacturing a polished wafer.

[Beneficial effect] The polishing pad, the manufacturing method of the polishing pad, and the polishing method using the polishing pad according to the embodiments can maintain the cutting rate at the same level as the conventional polishing pad and can significantly reduce the number of defects.

Hereinafter, in order to enable those of ordinary skill in the technical field of the present invention to easily implement it, the embodiments are described in detail with reference to the accompanying drawings. However, the present invention can be implemented in various different embodiments, and is not limited to the embodiments described here.

The terms "approximately", "substantially", etc. used in this specification are used within the inherent manufacturing and material tolerances with their numerical values or close to their numerical meanings in order to facilitate the understanding of the present invention and prevent maliciousness. Of infringers improperly use public content involving accurate or absolute values.

Throughout the specification, the term "combination of them" included in the expression of the Markush method means a mixture or combination of one or more selected from the group consisting of the constituent elements described in the expression of the Markush method. It means to include one or more selected from the group consisting of the aforementioned constituent elements.

Throughout this manual, "A and/or B" means "A or B, A and B".

Throughout the specification, unless otherwise specified, terms such as "first", "second" or "A", "B" are used to distinguish the same terms.

In this specification, B is located on A means that B is located on A in direct contact, or that B is located on A with other layers between A and B. Therefore, it should not be construed as limiting B to A. The way of surface contact is located on A.

In this specification, unless otherwise specified, the expression of the singular number is interpreted to include the meaning of the singular or plural number explained in the context.

In this specification, defects refer to polishing defects, such as small bends or chatter marks.

The polishing pad used for chemical mechanical polishing technology should polish the substrate quickly and accurately without any defects (scratches, defects) on the surface of the substrate. In the process of researching a polishing pad that maintains other characteristics above the same level and reduces the number of defects, the inventor has manufactured a polishing pad with a high contact angle to the slurry solution in order to prevent the slurry particles from adhering to the polishing pad, and confirmed The use of the polishing pad can significantly reduce the number of defects on the wafer, thereby completing the present invention.

Fig. 1 is a conceptual diagram illustrating a cross section of a polishing pad according to an embodiment. The present invention will be described in more detail with reference to FIG. 1, the polishing pad 100 contains polyurethane, and the polyurethane contains a silane-based repeating unit represented by the following Chemical Formula 1: [Chemical Formula 1]

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

Specifically, in Chemical Formula 1, R ₁₁ and R ₁₂ may each independently be hydrogen or a C ₁ -C ₅ alkyl group, and n may be an integer from 8 to 28.

Since the silane-based repeating unit is contained in the main chain of the polyurethane, the polishing pad 100 can be polished stably during the chemical mechanical polishing process and can reduce defects on the polished substrate. In particular, when a vapor-phase silica slurry is used, the polishing pad 100 is very effective in suppressing defects on the substrate after polishing.

[化學式2-2]

Specifically, the polyurethane may contain a repeating unit represented by the following Chemical Formula 2-1 or 2-2: [Chemical Formula 2-1]

[Chemical formula 2-2]

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

Specifically, in the chemical formula 2-1 or 2-2, R ₁₁ and R ₁₂ are each independently hydrogen or a C ₁ -C ₅ alkyl group, and R ₂₁ is -Si(R ₁₃ )(R ₁₄ )(R ₂₂ ) , R ₁₃ and R ₁₄ are each independently hydrogen or C ₁ -C ₅ alkyl, R ₂₂ is -(CH ₂ ) _m1 -or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 (wherein, m1, m2 and m3 are each independently an integer from 2 to 12), and n is an integer from 8 to 28.

The polishing pad 100 may include 0.1 to 5% by weight of the silane-based repeating unit represented by the chemical formula 2-1 or 2-2. In this case, as expected by the present invention, the phenomenon that the slurry particles adhere to the surface or pores of the polishing pad can be appropriately and effectively suppressed.

[化學式2-4]

Specifically, the chemical formula 2-1 or 2-2 may be the following chemical formula 2-3 or 2-4, respectively: [Chemical formula 2-3]

[Chemical formula 2-4]

In the chemical formulas 2-3 and 2-4, n is an integer from 8 to 28, and the p is an integer from 1 to 10. Specifically, in the chemical formula 2-3 or 2-4, n may be an integer from 10 to 25, and p may be an integer from 1 to 5.

The polyurethane having the above-mentioned characteristics can be applied to the polishing pad 100 as a whole, or can be applied to the top pad 10 in the structure of the polishing pad including the top pad 10 and the sub-pad 30.

The polyurethane may be a polyurethane in the form of a foam.

When manufacturing the polyurethane, a foaming agent may be mixed in the composition to prepare the polyurethane in the foam form. The foaming agent can be formed by mixing any foam selected from the group consisting of gaseous foam, solid foam, liquid foam and combinations thereof.

When the polishing pad 100 including the top pad 10 and the vapor-phase silica slurry are used, the polishing pad 100 can reduce the number of defects on the surface of the wafer after polishing. The number of the reduced defects may be 40 or less, 25 or less, 10 or less, or 0 or more.

The wafer may be in the shape of a disc having a diameter of about 300 mm or more. The surface area of the wafer may be about 70685.83 square millimeters (mm ² ) or more. The number of defects is based on measurement at the surface area.

The defects are the results of evaluation using defect detection equipment (manufacturing company: Tencor, model: XP+) after polishing the silicon wafer with a CMP polishing machine, cleaning and drying.

The polishing is based on the following: a 300 mm silicon wafer deposited with silicon oxide is installed in a CMP polishing machine, so that the silicon oxide layer of the silicon wafer contacts the surface of the platen to which the polishing pad 100 is attached. Polished under a polishing load of psi while rotating at 150 revolutions per minute (rpm) for 60 seconds. At this time, the slurry can use, for example, vapor-phase silica slurry or cerium oxide slurry.

Specifically, the pH of the gas phase silica slurry is 10.5, and may contain 12% by weight dispersed therein gas phase silica having an average particle diameter of 150 nanometers (nm).

Specifically, the gas phase silica slurry prepared by the following method can be used.

Prepare a basic solution of pH 10.5 containing the first pH adjuster and ultrapure water. At this time, ammonia, potassium hydroxide, sodium hydroxide, etc. can be used as the first pH adjuster. A small amount of 12% by weight of fumed silica (OCI company) was added to the basic solution in batches, and mixed using an ultra sonicator at a speed of 9000 revolutions per minute (rpm) to Prepare the silicon dioxide base solution. After performing the dispersion process for about 4 hours, use a high-pressure homogenizer to perform a further dispersion process, add 0.5 to 2% by weight of ammonium additives, and stir for another 1 hour. Thereafter, 0.01 to 0.1% by weight of a nonionic surfactant (for example, 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, or sulfonic acid, etc. can be used as the second pH adjuster. After filtering the mixed slurry solution through a slurry screening program (Micropore Company) with a pore size of 3.5 μm and 1 μm, the final gas-phase silica slurry is prepared. The final gas phase silica slurry had a pH of 10.5 and contained 12% by weight dispersed therein gas phase silica having an average particle size of 150 nm (measurement: nano-ZS 90, Malvern Company). The slurry prepared in this way is used as the gas phase silica slurry standard solution in the subsequent contact angle measurement.

When the polishing pad 100 is used with a cutting rate of 45 to 55 microns/hour (μm/hr), it can have low defect characteristics such that silicon wafers have 40 or less, 25 or less, and 10 or less defects.

When the polishing pad 100 is used at a polishing rate of 2600 to 2900 Å/min (Å/min), it can have a low defect characteristic that silicon wafers have 40 or less, 25 or less, and 10 or less defects.

_{The contact angle difference (Ad (pf)} , %) of the polishing pad 100 according to Equation 1 below may be a value of 1.5 to 5 or 2 to 4. [Equation 1] Ad _(pf)= [100×(Ap-Af)]/Ap

In Equation 1, Ap is the contact angle of pure water, Af is the contact angle of the vapor phase silica slurry, and Ad _(pf) is the difference between the contact angles defined by Equation 1 above.

When the difference in the contact angle is within the above range, when the substrate is polished with vapor-phase silica slurry, the polishing rate and cutting rate can be maintained at substantially the same or higher level as that of conventional polishing pads, and can be significantly reduced Defect degree.

The contact angle is measured at room temperature. A gas-phase silica slurry having a pH of 10.5 and containing a gas-phase silica having an average particle diameter of 150 nanometers dispersed therein was used as a reference. In addition, the specific composition and preparation method of the gas phase silica slurry used as a reference for the contact angle measurement are the same as the above description, and therefore the description thereof is omitted.

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

The contact angle of the polishing pad 100 to pure water may be 85° to 125°.

The difference between the contact angle of the polishing pad 100 to pure water and the contact angle measured with the vapor-phase silica slurry may be more than 1.5°, more than 1.8°, or more than 2°.

The contact angle of the polishing pad 100 with respect to pure water and the contact angle measured with the vapor-phase silica slurry may differ by 1.2 to 5° or 1.5 to 4°.

As mentioned above, for the polishing pad 100 with a large difference between the contact angle of pure water and the contact angle of vapor-phase silica slurry, the repulsive force between the surface of the polishing pad and the slurry particles may increase when it comes into contact with the polishing slurry. . Therefore, the adhesion of slurry particles to the surface or pores of the polishing pad can be significantly reduced, and excellent polishing quality can be obtained.

When the polishing pad 100 having a large difference in contact angle with the slurry as described above is a foamed pad, it has a more significant defect reduction effect. The particles contained in the slurry may enter and adhere to the surface pores of the foam polishing pad. At this time, defects will be formed on the surface of the polished substrate. The polishing pad of the present invention can significantly reduce this phenomenon, and the defect reduction effect is considered to be more significant.

In the polishing pad 100, the polyurethane main chain contains silane-based repeating units, which in particular induces an increase in the repulsive force between the silica particles and the surface of the polyurethane. Based on this, the polishing pad maintains the polishing rate and cutting rate of the polishing pad using the slurry at substantially the same level or above, while significantly reducing the degree of defect generation.

The polishing pad 100 includes: a top pad 10; a first adhesive layer 15 provided on one surface of the top pad; and a sub-pad 30 provided on one surface of the first adhesive layer 15.

The top pad 10 may be composed of polyurethane in the form of a foam having the characteristics described above. The top pad 10 may be a foam with an average pore size of 10 to 30 um. The advantage of using a top pad with such an average pore size is to improve 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 to 44%. The top pad 10 may be a polyurethane in the form of a foam with a number of pores per unit area (about 0.3 square centimeters (cm ^{2 )) of 350 to 500.} When the polyurethane top pad 10 in the form of a foam with such characteristics is used, wafer polishing can be effectively performed.

The Shore D hardness of the top pad 10 can be in the range of 55 to 65, at which time the polishing efficiency can be improved.

The thickness of the top pad 10 can be in the range of 1.5 to 3 millimeters. In this case, the polishing efficiency can be improved.

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

The sub-pad 30 may be a non-woven fabric or suede leather type.

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

The top pad 10 can be attached to the sub-pad 30 through a hot-melt adhesive layer 15.

A rubber adhesive 35 (second adhesive layer) may be used on the other surface of the sub-pad 30.

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

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

The polishing pad 100 according to another embodiment includes the top pad 10 as a polyurethane polishing layer.

The polyurethane polishing layer includes a foam of a urethane composition containing a urethane prepolymer, a curing agent, and a foaming agent.

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

The silane-based compounds are compounds capable of reacting with isocyanates, such as silane-modified polyols and silane-modified amines, to introduce silane-based repeating units into the main chain of ethyl carbamate.

Specifically, the silane-based compound may contain the silane-based repeating unit of Chemical Formula 1 below, and at least one terminal includes a hydroxyl group, an amino group, or an epoxy group. [Chemical formula 1]

In Chemical Formula 1, _{the specific description of R 11} , R ₁₂ , and n overlaps with the above description, so the description is omitted.

Based on the total weight of the prepolymer composition, the content of the silane compound may be 0.1 to 5% by weight. Based on the total weight of the prepolymer composition, the content of the silane compound may be 1 to 3% by weight or 1.5 to 2.5% by weight.

Based on the total weight of the prepolymer composition, if the silane-based compound is less than 0.1% by weight, the defect reduction effect caused by the inclusion of the silane-based compound may be very small. If it exceeds 5% by weight, the synthesis process Gelation may occur during the process, making it difficult to perform the synthesis to obtain the desired physical properties. When the silane compound is contained in the above content, a polyurethane polishing pad with excellent defect reduction effect can be provided.

Specifically, compared with polyurethane in the form of foam that does not include the silane-based repeating unit represented by the chemical formula 1, the top pad 10 can reduce the degree of defects of the polished silicon wafer by more than 80% and more than 85%. In addition, the top pad 10 can reduce the degree of defects of the polished silicon wafer by more than 90% compared with polyurethane in the form of a foam that does not include the silane-based repeating unit represented by the chemical formula 1.

The degree of such defects is a value obtained at the same level as the conventional polyurethane polishing pad such as cutting rate and polishing rate, which can significantly reduce the defect rate of silicon wafers caused by defects.

The silane-based compound may be a compound represented by the following Chemical Formula 3: [Chemical Formula 3]

In Chemical Formula 3, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen or C ₁ -C ₁₀ alkyl, 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 from 1 to 20), R ₃₁ is a C ₁ -C ₂₀ alkylene group, and R ₄₁ and R ₄₂ are each independently a hydroxyl group or an amino group Or 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 C1-C5 alkyl, and R ₂₂ is -(CH ₂ ) _m1 -or -(CH ₂ ) _m2 -( OCH ₂ CH ₂ ) _m3- (wherein m1, m2 and m3 are each independently an integer from 2 to 12), R ₃₁ is a C ₁ -C ₁₀ alkylene group, and R ₄₁ and R ₄₂ are each independently a hydroxyl group or an amine Group or epoxy group, n is an integer of 8-28.

More specifically, in Chemical Formula 3, R ₁₁ , R ₁₂ , R ₁₃ and R 14 are each independently hydrogen, methyl or ethyl, and R ₂₂ is -(CH ₂ ) _m1 -or -(CH ₂ ) _m2 -( OCH ₂ CH ₂ ) _m3- (wherein m1, m2 and m3 are each independently an integer from 2 to 12), R ₃₁ is a C1-C5 alkylene group, R ₄₁ and R ₄₂ are each independently a hydroxyl group, an amino group or Epoxy group, n is an integer of 10-25.

The isocyanate compound can be selected from p-phenylene diisocyanate, 1,6-hexamethylene diisocyanate, toluene diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, 4,4-diphenyl Any one of the group consisting of methane diisocyanate, cyclohexylmethane diisocyanate, and combinations thereof, but not limited thereto.

The alcohol compound may include a polyhydric alcohol compound or one or more monomeric alcohol compounds.

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

The monomeric alcohol compound can be selected from any one of the group consisting of ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, methyl propylene glycol, and combinations thereof, but is not limited thereto.

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

Based on 1 part by weight of the isocyanate compound, the prepolymer composition may include 0.7 to 1.3 parts by weight of the alcohol compound, and may include 0.05 to 7% by weight of the silane-based compound.

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

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

When the prepolymer composition is constituted in the above range, a polyurethane having physical properties more suitable for polishing pads can be produced.

The NCO% of the prepolymer may be in the range of 8 to 12%. When the NCO% is within this range, a porous polyurethane pad in the form of a foam with suitable hardness can be manufactured.

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

Specifically, the amine curing agent can be selected from 4,4'-methylene bis(2-chloroaniline), m-phenylenediamine, diethyl toluene diamine, hexamethylene diamine and combinations thereof. Any sheet in the group.

The foaming agent can be a gaseous foaming agent, a solid foaming agent, a liquid foaming agent or a combination thereof.

Specifically, the gaseous blowing agent may be an inert gas, such as nitrogen or carbon dioxide gas.

The solid foaming agent may be in the form of organic hollow spheres and/or inorganic hollow spheres. For example, microspheres in which hydrocarbon gas is encapsulated by a polymer may be used.

The liquid foaming agent can be Galden solution (Tri perfluoropropyl amine), liquid carbon dioxide, liquid hydrofluorocarbon, etc., but is not limited thereto.

The urethane composition may further include a surfactant. The surfactant may be a nonionic or ionic surfactant. Specifically, the surfactant may be an organosilicon surfactant, for example, including at least one block containing polydimethylsiloxane and at least one containing polyether, polyester, polyamide or polycarbonate segment. Another block copolymer, but not limited to this.

Based on 100 parts by weight of the urethane prepolymer, the urethane composition may include 10 to 60 parts by weight of the curing agent, 0.1 to 10 parts by weight of the foaming agent, and 0.1 to 2 parts by weight of the surfactant.

In addition, when a gaseous foaming agent is used as the foaming agent, it can be released at a rate of 0.1 to 2.0 liters per minute (L/min). When the urethane is constituted in the above ratio, a polyurethane in the form of a foam having suitable physical properties of the polishing pad can be formed.

A method for preparing a urethane prepolymer for a polishing pad according to another embodiment of the present invention includes a prepolymer preparation step, reacting the prepolymer composition at 50 to 120°C, thereby preparing NCO% Is 8 to 12% of the urethane prepolymer, wherein the prepolymer composition includes an isocyanate compound, an alcohol compound, and a silane-based compound, the silane-based compound contains the silane-based repeating unit of Chemical Formula 1, and At least one terminal contains a hydroxyl group, an amino group or an epoxy group.

The preparation step of the prepolymer may include: a first process, mixing the isocyanate compound and the alcohol compound to prepare a first composition, and reacting at 60 to 100° C. for 1 to 5 hours to prepare the first polymer The second process is to mix the first polymer and the silane compound to prepare a second composition, and react at 60 to 100° C. for 0.5 to 3 hours to prepare a second polymer.

The specific description of the isocyanate compound, the alcohol compound, the silane-based compound, the prepolymer composition, etc., is the same as the above description, so the description is omitted.

The manufacturing method of the polishing pad 100 according to another embodiment of the present invention includes: a polyurethane forming process, mixing a urethane composition, and performing a polymerization reaction to form a foam form containing a silane-based repeating unit represented by the chemical formula 1 Polyurethane, the top pad manufacturing process, the top pad 10 containing the polyurethane, and the lamination process, bonding the top pad to the sub pad (sub pad), manufacturing the polishing pad, so that the main chain of the polyurethane contains the chemical formula 1 represents a polyurethane polishing pad 100 of silane-based repeating units.

The urethane composition contains: a urethane prepolymer used in a polishing pad, a curing agent, and a foaming agent.

The specific descriptions of the isocyanate compound, the alcohol compound, the silane-based compound, the prepolymer composition, and the urethane composition are the same as those described above, so the descriptions are omitted.

A manufacturing method for polishing a wafer according to another embodiment of the present invention includes: a preparation step of mounting the above-described polishing pad 100 and an unpolished wafer in a CMP polishing machine; and a polishing step of adding the polishing pad 100 and the unpolished wafer to the CMP polishing machine. A polishing slurry is thrown in, and the unpolished wafer is polished with the polishing pad, thereby manufacturing a polished wafer.

Specifically, the unpolished wafer may be a silicon wafer, for example, a silicon wafer deposited with silicon oxide.

The polishing slurry can be a polishing slurry containing vapor-phase silica, colloidal silica, cerium oxide, or the like.

The polishing may be performed by pressing in such a manner that the unpolished wafer and/or the polishing pad are in contact with each other, and the pressing may be 1 to 7 psi.

The polishing may be performed by rotating the unpolished wafer and/or the polishing pad, and the rotation speed may be 10 to 400 revolutions per minute (rpm).

The polishing can be performed for 1 to 10 minutes, and the polishing time can be increased or decreased as needed.

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

The cleaning step includes cleaning and polishing the wafer with pure water and inert gas (for example, nitrogen) after being separated from the CMP polisher.

The polishing pad of the embodiment is used in the above-mentioned method for manufacturing a polished wafer, so that a polished wafer with a reduced number of defects can be produced while having an excellent polishing rate and cutting rate.

Hereinafter, the present invention will be explained more specifically.

1. Manufacturing of polishing pads

Example 1 Manufacturing of thin plates for top pads

Put toluene diisocyanate (TDI, Toluene Diisocyanate) as isocyanate compound, polytetramethylene ether glycol (PTMEG, Polytetramethylene ether glycol) and diethylene glycol as polyol compound into a four-necked flask , React at 80°C for 3 hours to obtain a first-level reaction product. Put the first-level reaction product and silane-modified polyol (Wacker® IM11, Mw: 1000) into a four-necked flask and react at 80°C for 2 hours to prepare a prepolymer with an NCO% of 8-12% by weight.物(Prepolymer). At this time, based on the total weight of the prepolymer, the amount of the silane-modified polyol is 2% by weight.

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 prepared above, and the curing agent tank is filled with bis(4-amine). Bis(4-amino-3-chlorophenyl)methane (bis(4-amino-3-chlorophenyl)methane, Ishihara Company). Use nitrogen (N ₂ ) as the inert gas. Mix solid foaming agent (Akzonobel) and silicon surfactant (Evonik) through a separate pipeline or mix with the prepolymer.

In the above-prepared casting machine, the equivalent ratio of the prepolymer and the curing agent is adjusted to 1:1, and the raw materials are released and cast at a rate of 10 kilograms per minute (kg/min). _{At this time, nitrogen (N 2} ) as an inert gas was supplied at a rate relative to the total flow rate shown in Table 1.

After mixing in the mixing head and adding the raw materials at high speed, a controlled amount of inert gas is introduced into a mold with a size of 1000 mm in width, 1000 mm in length, and 3 mm in height to obtain a specific gravity of 0.8-0.9 grams per cubic centimeter (g /cc) The top pad sheet 10 of Example 1 with pores (Pore).

Example 2 Manufacturing of thin plates for top pads

Put toluene diisocyanate (TDI, Toluene Diisocyanate) as isocyanate compound, polytetramethylene ether glycol (PTMEG, Polytetramethylene ether glycol) and diethylene glycol as polyol compound into a four-necked flask , React at 80°C for 3 hours to obtain a first-level reaction product. Put the first-level reaction product and silane-modified polyol (Wacker® IM22, Mw: 2000) into a four-necked flask and react at 80°C for 2 hours to prepare a prepolymer with an NCO% of 8-12% (Prepolymer). At this time, based on the total weight of the prepolymer, the amount of the silane-modified polyol is 2% by weight.

The sheet 10 for a top pad of Example 2 was manufactured in the same manner as in Example 1, except that the prepolymer prepared in Example 2 above was used.

Comparative example 1 Manufacturing of thin plates for top pads

Put toluene diisocyanate (TDI, Toluene Diisocyanate) as an isocyanate compound, polytetramethylene ether glycol (PTMEG, Polytetramethylene ether glycol) and diethylene glycol as a polyol compound into a four-necked flask , The reaction was carried out at 80°C to prepare a prepolymer with an NCO% of 8-12%.

A sheet for a top pad of Comparative Example 1 was manufactured in the same manner as in Example 1, except that the prepolymer prepared in Comparative Example 1 described above was used.

[Table 1] Dosage during casting Example 1 Example 2 Comparison column 1 Prepolymer (parts by weight) 100 100 100 Curing agent (parts by weight) 25 25 25 Surfactant (parts by weight) 0.2-1.5 0.2-1.5 0.2-1.5 Solid foaming agent (parts by weight) 0.5-1.0 0.5-1.0 0.5-1.0 Inert gas (L/min (L/min)) 0.5-1.5 0.5-1.5 0.5-1.5

Manufacturing of polishing pads

According to a general method, each top pad sheet 10 is subjected to surface polishing and grooving processes in sequence, and the sub-pad 30 is laminated through the sub-pad 30 to produce a polishing pad 100 having the structure shown in FIG. 1.

2. Evaluation of physical properties of polishing pads

Strength and contact angle evaluation

Using the polishing pads of Example 1, Example 2 and Comparative Example 1 manufactured previously, the fumed silica slurry was used to measure the contact angle, evaluate the CMP polishing performance, and determine the number of defects in the wafer. Evaluation of physical properties such as measurement.

The center part of the manufactured polishing pad without groove (Groove) was cut into a sample of 2 cm x 2 cm (cm) in vertical and horizontal directions, and a contact angle analyzer (Dynamic Contact Angle Analyzer, model: DCA-312, manufacturing company: CAHN) was used. ) Measure the contact angle of the sample.

After installing the samples of Examples 1 and 2 on the analyzer, the syringes were filled with pure water (H ₂ O) and fumed silica slurry (Fumed silica Slurry), and then an appropriate amount was injected onto the sample. , And evaluate by measuring the shape of droplets on the sample with an analyzer. The composition and preparation process of vapor phase silica slurry will be explained separately.

Preparation of fumed silica slurry

Prepare a pH = 10.5 solution consisting of the first pH adjusting agent (such as amine, potassium hydroxide, sodium hydroxide, etc.) and ultrapure water. About 12% by weight of fumed silica slurry (Fumed silica Slurry, OCI) was added to the solution in small batches, and dispersed using an ultra sonicator at a rate of 9000 revolutions per minute (rpm). After about 4 hours of dispersion process, use a high-pressure homogenizer for further dispersion operation.

After being fully dispersed, add 0.5-2% by weight of ammonium additive, and then stir for 1 hour. Thereafter, 0.01-0.1% by weight of a nonionic surfactant is added, and a second pH adjusting agent (such as ammonia, potassium hydroxide, sodium hydroxide, nitric acid, sulfonic acid, etc.) is used to adjust the pH of the solution to 10.5.

The final gas phase silica slurry is obtained through filtration through a slurry screening program (Micropore Corporation) with a pore size of 3.5 microns and 1 micron. The physical properties of the final vapor phase silica slurry are pH=10.5 and average particle size=150nm (nano-ZS 90, Malvern).

Table 2 below shows the physical properties of the top pad manufactured previously, and the physical properties of the sub-pad and polishing pad as a whole.

[Table 2] distinguish Evaluation project Example 1 Example 2 Comparison column 1 Physical properties Top pad Thickness (mm) 2 2 2 Hardness (Shore D) 59 59.5 59.8 Average pore size (um) 28 27 28 Specific gravity (g/cc) 0.8 0.8 0.8 Tensile strength (N/mm ² ) 21.1 20.9 20.8 Elongation(%) 126 125 123 Shore D hardness value at different temperatures (30°C/50°C/70°C) 58/54/51 58/54/51 58/54/51 Contact angle Ap (°, H ₂ O) 90 89 71 Contact angle Af (°, fumed silica slurry) 88 86 70 Difference in contact angle* 2.22% 3.37% 1.41% Submat Types of Non-woven fabric Non-woven fabric Non-woven fabric Thickness (mm) 1.1 1.1 1.1 Hardness (Asker C) 70 70 70 Polishing pad Thickness (mm) 3.32 3.32 3.32 Compression ratio(%) 1.05 1.05 1.05 *The difference in contact angle (Ad _(pf) , %) is _{calculated by Ad (pf)} =[100×(Ap-Af)]/Ap, where Ap is the contact angle measured with pure water, and Af is used Contact angle measured by vapor phase silica slurry. Measure at the same room temperature.

With reference to the results in Table 2 above, it can be confirmed that in terms of hardness, average pore size, specific gravity and other characteristics, Comparative Example 1 and Example 1 and Example 2 are similar, but for pure water and vapor-phase silica slurry ( There is a big gap in the contact angle of Fumed silica slurry.

Evaluation of the pore physical properties of the top pad

The pores of the top pad were photographed by SEM (JEOL) at 100 times magnification, and the number, size, and area ratio were measured. The results are shown in Figure 2 and Table 3 below.

[table 3] Pore physical properties of the top pad Example 1 Example 2 Comparison column 1 Number average diameter (um) 28.3 26.8 28 Quantity/0.3 square centimeter (cm ² ) (ea) 412 405 402 Area ratio (%) 40.1 40 39.8

Polishing performance evaluation

Using the polishing pads of Example 1, Example 2 and Comparative Example 1 manufactured previously, the removal rate and pad cut-rate of the polishing pad (pad cut-rate, µm/hr) were measured by the following method. )), the number of defects in polished wafers.

1) Measurement of polishing rate

A silicon wafer with a diameter of 300 mm on which silicon oxide is deposited through a CVD process is installed in a CMP polishing machine, with the silicon oxide layer of the silicon wafer facing down, and placed on a pressure plate bonded to the porous polyurethane polishing pad. After that, the polishing load was adjusted to 4.0 psi, the polishing pad was rotated at 150 revolutions per minute (rpm), and the sintered cerium oxide slurry was poured onto the polishing pad at a rate of 250 milliliters/minute (ml/minute), and at the same time Rotate the platen at 150 revolutions per minute (rpm) for 60 seconds to polish the silicon oxide film. After polishing, the silicon wafer is separated from the carrier, installed in a spin dryer, cleaned with DIW, and dried with nitrogen for 15 seconds. A spectral interferometer (manufacturing company: Kyence, model: SI-F80R) was used to measure the thickness changes of dried silicon wafers before and after polishing.

The polishing rate is calculated by the following formula 2:

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

2) Measurement of cutting rate

Each polishing pad was initially pretreated with deionized water for 10 minutes, and then treated by spraying deionized water for 1 hour. At this time, the thickness change was measured during the treatment period of 1 hour.

The device used for processing is AP-300HM of CTS Company, the processing pressure is 6 lbf (pound-force), the rotation speed is 100-110 revolutions per minute (rpm), and the pad used for processing is SAESOL LPX -DS2.

3) Measurement of defects

Polishing was performed in the same manner as the polishing rate measurement method of 1) above using a CMP polisher.

After polishing, the silicon wafer was transferred to a cleaner and cleaned with 1% by weight HF, pure water (DIW), 1% by weight H ₂ NO ₃ , and pure water (DIW) for 10 seconds, respectively. After that, it was transferred to a spin dryer and washed with purified water (DIW), then dried with nitrogen for 15 seconds.

Use defect inspection equipment (manufacturing company: Tencor, model: XP+) to measure the change of defects before and after polishing of the dried silicon wafer.

Table 4, Figure 3 and Figure 4 below show the polishing rate, cutting rate, and number of defects (based on the surface of a disk-shaped wafer with a diameter of about 300 mm).

[Table 4] Example 1 Example 2 Comparison column 1 Polishing rate (RR) (Å/min (Å/min)) 2733 2754 2759 Number of defects (#Defect, each) 7 5 50 Cutting rate (micron/hour (µm/hr)) 51 53 50 Compared with the comparative example, the defect reduction rate (%)* 86% 90% - *The defect reduction rate (%) was calculated by [(the number of defects in Comparative Example 1)-(the number of defects in Example 1)×100]/(the number of defects in Comparative Example 1).

With reference to the above measurement results, it can be confirmed that the polishing rate and cutting rate of the polishing pads of Example 1 and Example 2 are similar to those of Comparative Example 1, and the number of defects of polished wafers is significantly reduced.

Above, the embodiments are described in detail, but the scope of protection of the present invention is not limited to this. Various modifications and improvements made by those of ordinary skill in the art using the basic concepts of the embodiments as defined by the scope of the patent application shall belong to the protection of the present invention. range.

100: polishing pad 10: Top pad, polishing layer 15: The first adhesive layer 30: bottom pad, sub pad 35: second adhesive layer 50: Film 55: third adhesive layer

FIG. 1 is a conceptual diagram illustrating a cross-section of a polishing pad including a top pad according to an embodiment. 2 is the result of observing the pores of the top pads of Example 1 (a), Example 2 (b) and Comparative Example 1 (c) manufactured in Examples with an electron microscope. FIG. 3 is a graph comparing the polishing rate (top) and the cutting rate (bottom) of the polishing pad prepared in the example. 4 is a graph comparing the measurement results of the number of defects (#defect, a disc shape with a diameter of about 300 millimeters (mm)) of a silicon wafer polished using the polishing pad prepared in the example.

Claims (15)

A polishing pad, comprising: polyurethane, the polyurethane contains a silane repeating unit represented by chemical formula 1 in its main chain, and a substrate polished through the polishing pad and vapor phase silica slurry has a low defect of 40 or less Defect characteristics, [Chemical formula 1]

In Chemical Formula 1, R ₁₁ and R ₁₂ are each independently hydrogen or a C ₁ -C ₁₀ alkyl group, and n is an integer of 1-30. The polishing pad described in item 1 of the scope of patent application, wherein the polyurethane contains a repeating unit represented by Chemical Formula 2-1 or Chemical Formula 2-2 in its main chain: [Chemical Formula 2-1]

[Chemical formula 2-2]

In Chemical Formula 2-1 or Chemical Formula 2-2, R ₁₁ and R ₁₂ are each independently hydrogen or C ₁ -C ₁₀ alkyl, R ₂₁ is -Si(R ₁₃ )(R ₁₄ )(R ₂₂ ), R ₁₃ and R ₁₄ are each independently hydrogen or C ₁ -C ₁₀ alkyl, R ₂₂ is -(CH ₂ ) _m1 -or -(CH ₂ ) _m2 -(OCH ₂ CH ₂ ) _m3 , where m1, m2 and m3 is each independently an integer from 1 to 20, and n is an integer from 1 to 30. The polishing pad described in item 1 of the scope of patent application, wherein the contact angle difference (Ad _(pf) , %) of the polishing pad according to Equation 1 is 1.5 to 5, [Equation 1] Ad _{(pf) =} [100×(Ap-Af)]/Ap In Equation 1, Ap is the contact angle measured with pure water, and Af is the contact angle measured with vapor-phase silica slurry. The polishing pad described in item 1 of the scope of patent application, wherein The polyurethane is in the form of a foam, and the average pore size of the foam is 10 to 30 microns. The polishing pad described in item 1 of the scope of patent application, wherein The Shore D hardness of the polyurethane is 55 to 65. The polishing pad described in item 1 of the scope of patent application, wherein The polishing pad includes a top pad and a sub-pad arranged on the top pad, The top pad includes the polyurethane, The sub-pad is a non-woven fabric or suede type material. A polishing pad, comprising: a top pad as a polyurethane polishing layer, the polyurethane polishing layer contains a foam of a urethane composition, the urethane composition includes a urethane prepolymer, A curing agent and a foaming agent, the urethane prepolymer is a copolymer of a prepolymer composition, the prepolymer composition includes an isocyanate compound, an alcohol compound, and a silane compound, the silane compound The silane-based repeating unit includes a hydroxyl group, an amino group or an epoxy group at at least one end thereof, and the silane-based repeating unit is represented by the following chemical formula 1: [Chemical formula 1]

In Chemical Formula 1, R ₁₁ and R ₁₂ are each independently hydrogen or a C ₁ -C ₁₀ alkyl group, and n is an integer of 1-30. The polishing pad described in item 7 of the scope of patent application, wherein Based on the entire prepolymer composition, the content of the silane compound is 0.1 to 5% by weight. The polishing pad described in item 7 of the scope of patent application, wherein Compared with polyurethane in the form of foam without the silane-based repeating unit represented by Chemical Formula 1, the top pad reduces the degree of defects of the polished silicon wafer by more than 80%. The polishing pad described in item 7 of the scope of patent application, wherein the silane-based compound is a compound represented by Chemical Formula 3: [Chemical Formula 3]

In the chemical formula 3, R _{11 ,} R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen or a C ₁ -C ₁₀ alkyl group, 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 from 1 to 20, R ₃₁ is a C ₁ -C ₂₀ alkylene group, and R ₄₁ and R ₄₂ are each independently a hydroxyl group, an amino group or a ring Oxy group, n is an integer of 1-30. The polishing pad described in item 7 of the scope of patent application, wherein The NCO% of the prepolymer is 8 to 12% by weight. A method for manufacturing a polishing pad includes: a polyurethane forming process, forming the polyurethane in the form of a foam by polymerizing an urethane composition, a top pad manufacturing process, manufacturing a top pad containing the polyurethane, and a lamination process , The top pad and the sub-pad are fixed to manufacture a polishing pad; wherein, the urethane composition includes a urethane prepolymer, a curing agent and a foaming agent, and the polyurethane is in its The main chain contains a silane-based repeating unit represented by the following chemical formula 1, [Chemical formula 1]

In Chemical Formula 1, R ₁₁ and R ₁₂ are each independently hydrogen or a C ₁ -C ₁₀ alkyl group, and n is an integer of 1-30. The manufacturing method of polishing pad as described in item 12 of the scope of patent application, wherein The urethane prepolymer is prepared through the preparation method of the urethane prepolymer, The preparation method of the urethane prepolymer includes a prepolymer preparation step. In the prepolymer preparation step, the prepolymer composition is reacted at 50 to 120° C. to prepare NCO weight% 8 to 12% of urethane, wherein the prepolymer composition contains isocyanate compounds, alcohol compounds and silane compounds, The silane-based compound contains the silane-based repeating unit of Chemical Formula 1, and at least one terminal contains a hydroxyl group, an amino group or an epoxy group. The manufacturing method of polishing pad as described in item 12 of the scope of patent application, wherein The preparation steps of the urethane prepolymer include: In the first process, the isocyanate compound and the alcohol compound are mixed to prepare a first composition, and reacted at 60 to 100° C. for 1 to 5 hours to form a first polymer; and The second process is to mix the first polymer and the silane compound to prepare a second composition, and react at 60 to 100° C. for 0.5 to 3 hours to form a second polymer. A method for manufacturing a polished wafer includes: The preparation step is to install the polishing pad and unpolished wafer as described in item 1 of the scope of the patent application in the CMP polishing machine; and In the polishing step, polishing slurry is injected into the CMP polishing machine while polishing the unpolished wafer with the polishing pad, thereby manufacturing a polished wafer.

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