KR102129664B1 - Polishing pad, preparation method thereof, and polishing method applying of the same - Google Patents

Abstract

The present invention relates to a polishing pad having a reduced number of defects on a polished substrate, a manufacturing method thereof, a polishing method using the same, and the like, and includes a polyurethane containing a silane repeating unit in the main chain in the polishing pad, and the polishing pad and fumed There is provided a polishing pad having low defect characteristics of up to 40 defects on a substrate polished with silica slurry.

Description

Polishing pad, manufacturing method thereof and polishing method using the same{POLISHING PAD, PREPARATION METHOD THEREOF, AND POLISHING METHOD APPLYING OF THE SAME}

The present invention relates to a polishing pad having a reduced number of defects on a polished substrate, a manufacturing method thereof, and a polishing method using the same.

Polishing pads are used in Chemical Mechanical Planarization (CMP) to enable industrially easy fine surface processing, such as silicon wafers for semiconductor devices, memory disks, magnetic disks, optical lenses or reflective mirrors. It can be used in a variety of applications in planarization processing of materials requiring high surface flatness, such as optical materials, glass plates, and metals.

With the miniaturization of semiconductor circuits, the importance of the CMP process has been highlighted. CMP Pad (CMP Pad) is one of the essential raw materials in the CMP process during the semiconductor manufacturing process and plays an important role in realizing CMP performance.

CMP pads require various performances, but the number of defects in the material after planarization is a factor that greatly affects the yield, so it can be said to be a very important factor in distinguishing the long and short sides of the CMP pad.

Korean Patent Publication No. 10-2016-0132882, Polishing pad and its manufacturing method Domestic registered patent No. 10-0892924, polishing pad

An object of the present invention is to provide a polishing pad having a reduced number of defects on a polished substrate, a manufacturing method thereof, and a polishing method using the same.

In order to achieve the above object, the polishing pad according to an embodiment of the present invention includes i) a polyurethane containing a silane repeating unit represented by Chemical Formula 1 in the main chain in the polishing pad, and ii) the polishing pad and It has low-defect characteristics with 40 or fewer defects on the substrate polished with fumed silica slurry.

[Formula 1]

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

The polyurethane may include a repeating unit represented by Chemical Formula 2-1 or Chemical Formula 2-2 below in the main chain.

[Formula 2-1]

[Formula 2-2]

In Formula 2-1 or Formula 2-2, R ₁₁ and R ₁₂ are each independently hydrogen, 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, 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 from 1 to 20), and n is an integer from 1 to 30.

The polishing pad may have a contact angle difference value (Ad _(pf) , %) according to Equation 1 below from 1.5 to 5.

[Equation 1]

Ad _(pf) = [100*(Ap-Af)]/Ap

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

The polyurethane is in the form of a foam, the average pore size of the foam may be 10 to 30 μm.

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

The polishing pad may include a top pad including the polyurethane and a non-woven fabric or suede type sub pad located on one surface of the top pad.

The polishing pad according to another embodiment of the present invention includes a top pad that is a polyurethane-based abrasive layer comprising a foam of a urethane-based prepolymer, a curing agent, and a foaming agent, and the urethane-based prepolymer is an isocyanate. It is a copolymer of a prepolymer composition comprising a compound, an alcohol compound, and a silane-based compound comprising a silane-based repeating unit of Formula 1 and at least one terminal comprising a hydroxy group, an amine group, or an epoxy group.

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

The top pad may reduce the defect level of the polished silicon wafer by 80% or more, as compared to a foamed polyurethane that does not contain a silane repeating unit represented by Chemical Formula 1.

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

[Formula 3]

In Formula 3, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen, 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- (however, 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, and R ₄₁ and R ₄₂ are each Independently, it is a hydroxy group, an amine group, or an epoxy group, and n is an integer from 1 to 30.

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

Method for manufacturing a polishing pad according to another embodiment of the present invention, i) a urethane composition containing a urethane prepolymer, a curing agent, and a foaming agent is mixed and then subjected to polymerization to perform a silane-based repeating unit represented by Chemical Formula 1 below. Polyurethane forming process to form a foamed polyurethane containing; ii) a top pad manufacturing process for manufacturing a top pad comprising the polyurethane; And iii) lamination process of manufacturing the polishing pad by bonding the top pad with a sub pad (sub pad); including, to prepare a polyurethane polishing pad comprising a silane-based repeating unit represented by the formula (1) in the main chain .

The prepolymer may be prepared by a method for preparing a urethane prepolymer.

The preparation method of the prepolymer includes an isocyanate compound, an alcohol compound, and a prepolymer composition comprising a silane-based repeating unit represented by Chemical Formula 1 and at least one terminal comprising a silane-based compound containing a hydroxy group, an amine group, or an epoxy group. And a prepolymer preparation step of preparing a urethane prepolymer having 8 to 12% by weight of NCO by reacting at to 120°C.

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

Method for manufacturing a polished wafer according to another embodiment of the present invention, a preparation step of mounting the above-described polishing pad and the wafer before polishing to a CMP polishing apparatus: and the polishing while introducing a polishing slurry to the CMP polishing apparatus It includes; a polishing step of polishing the entire wafer using the polishing pad to produce a polished wafer.

The polishing pad of the present invention, a method of manufacturing the same, and a polishing method using the same, a polishing pad in which the number of defects is significantly reduced while maintaining the polishing rate and the cutting rate at the same level as in the prior art, a method of manufacturing the same, a wafer using the same A polishing method can be provided.

1 is a conceptual diagram illustrating a cross-section of a polishing pad including a top pad according to an embodiment of the present invention.
Figure 2 is a result of observing the pores of the top pad of Example 1 (a), Example 2 (b) and Comparative Example 1 (c) prepared in Examples of the present invention with an electron microscope.
Figure 3 is a graph comparing the polishing rate (top) and the cutting rate (bottom) of the polishing pad prepared in the embodiment of the present invention.
4 is a graph comparing the results of measuring the number of defects (#defect) of a silicon wafer polished using a polishing pad prepared in an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains may easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

As used herein, the terms “about”, “substantially”, and the like are used in or at a value close to that value when manufacturing and material tolerances specific to the stated meaning are given, and the understanding of the present invention. To help, accurate or absolute figures are used to prevent unconscionable abusers from unduly using the disclosed disclosure.

Throughout the present specification, the term “combination of these” included in the expression of the marki form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the marki form, the component. It means to include one or more selected from the group consisting of.

Throughout this specification, the description of “A and/or B” means “A, B, or A and B”.

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

In the present specification, the meaning that B is located on A means that B is directly in contact with A, or that B is located on A while another layer is positioned between them, and B is placed in contact with the surface of A. It is not limited to being interpreted.

In the present specification, a singular expression is interpreted to include a singular or plural number that is interpreted in context unless otherwise specified.

Polishing pads used in chemical mechanical polishing techniques must be polished so that substrates are polished quickly and accurately while at the same time there are no defects (scratches) on the substrate surface. While the inventors of the present invention were studying a method for reducing the number of defects while maintaining other characteristics of the polishing pad to be equal to or higher, a polishing pad having a high contact angle to the slurry solution was prepared so that the slurry particles did not adhere to the polishing pad. And the present invention was completed by confirming that the number of defects on the polished wafer can be significantly reduced.

1 is a conceptual diagram illustrating a cross section of a polishing pad according to an embodiment of the present invention. When the present invention is described in more detail with reference to FIG. 1, the polishing pad 100 according to an embodiment of the present invention includes polyurethane including a silane repeating unit represented by Chemical Formula 1 below.

[Formula 1]

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

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

In the polishing pad 100, a silane repeating unit represented by Chemical Formula 1 is included in the main chain of polyurethane, so that defects on the polished substrate can be reduced stably and relatively consistently during the chemical mechanical polishing process, particularly fumed silica. When applied for a slurry, the effect of suppressing defect generation on the polished substrate is large.

Specifically, the polyurethane may include a repeating unit represented by Formula 2-1 or Formula 2-2 below.

[Formula 2-1]

[Formula 2-2]

In Formula 2-1 or Formula 2-2, R ₁₁ and R ₁₂ are each independently hydrogen, 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, 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 from 1 to 20), and n is an integer from 1 to 30.

Specifically, in Formula 2-1 or Formula 2-2, R ₁₁ and R ₁₂ are each independently hydrogen, 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, 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- (where 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 a silane repeating unit represented by Chemical Formula 2-1 or Chemical Formula 2-2. In this case, it is possible to effectively suppress the occurrence of adhesion phenomenon in the polishing pad of the appropriate slurry particles intended in the present invention.

Specifically, Chemical Formula 2-1 or Chemical Formula 2-2 may be Chemical Formula 2-3 or 2-4 below.

[Formula 2-3]

[Formula 2-4]

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

Polyurethane having the above characteristics may be applied to the entire polishing pad 100 and may be applied to the top pad 10 in the structure of the polishing pad including the top pad 10 and the sub pad 30.

As the polyurethane, polyurethane in the form of a foam may be applied.

The polyurethane in the form of a foam may be formed by mixing any one foam selected from the group consisting of a gas phase foam, a solid foam, a liquid foam and a combination thereof in the composition at the time of manufacturing the polyurethane.

The polishing pad 100 may have low defect characteristics of 40 defects or less on a silicon oxide film polished by applying a fumed silica slurry and a polishing pad 100 including the top pad 10, 25 It may have the following low-defect characteristics, and may have 10 or less low-defect characteristics.

The above defect is a result of evaluating a silicon wafer polished using a CMP polishing machine using a defect measuring device (manufacturer: Tenkor, model name: XP+) after washing and drying.

After the polishing, a 300 mm silicon wafer having silicon oxide deposited thereon was installed on a CMP polishing apparatus, and then the silicon oxide layer of the silicon wafer was placed on the platen to which the polishing pad 100 was attached, and then the polishing load was 4.0. It is based on the polishing while rotating for 60 seconds at psi, 150 rpm. At this time, for example, a fumed silica slurry or a ceria slurry may be applied.

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

Specifically, the fumed silica slurry may be prepared by the following method.

A base solution, a solution having a pH of 10.5, including a first pH adjusting agent and ultrapure water, is prepared. In this case, ammonia, potassium hydroxide, sodium hydroxide, etc. may be applied to the first pH modifier. To the base solution, 12 wt% of fumed silica (OCI) was mixed at a speed of 9000 rpm using an ultrasonic sonicator and dispersed in small amounts to prepare a silica base solution. After the dispersion process was performed for about 4 hours, an additional dispersion process was performed using a high pressure disperser, and 0.5 to 2% by weight of an ammonium-based additive was added, followed by an additional stirring process for 1 hour. Thereafter, a mixed slurry solution having a pH of 10.5 is prepared by adding 0.01 to 0.1% by weight of a nonionic surfactant (eg, polyethylene glycol) and a second pH adjusting agent. Ammonia, potassium hydroxide, sodium hydroxide, nitric acid, sulfonic acid, etc. may be used as the second pH regulator. The mixed slurry solution was filtered by applying a filter for a slurry having a pore size of 3.5 um and 1 um (micropore), and then was used as the final fumed silica slurry. The final fumed silica slurry has a pH of 10.5 and an average particle size of 150 nm (measurement: nano-ZS 90, malvern) fumed silica 12% by weight. The prepared slurry is then applied as a standard solution for fumed silica slurry when measuring the contact angle.

The polishing pad 100 may have a low defect property of 40 or less defects of a silicon wafer, a low defect property of 25 or less, and 10 or less defects when the cutting rate is applied at 45 to 55 um/hr. It can have low defect characteristics.

When the polishing pad 100 is applied at a polishing rate of 2600 to 2900 Å/min, the defects of the silicon wafer may have low defect characteristics of 40 or less, and may have low defect characteristics of 25 or less, and 10 or less. It can have low defect characteristics.

The polishing pad 100 may have a contact angle difference value (Ad _(pf) , %) according to Equation 1 below having a value of 1.5 to 5, and a value of 2 to 4.

[Equation 1]

Ad _(pf) = [100*(Ap-Af)]/Ap

In Equation 1, the Ap is a contact angle measured with pure water, the Af is a contact angle measured with a fumed silica slurry, and A _d(pf) is a contact angle difference value defined by Equation 1 above.

When the difference in contact angle has the above value, by applying a fumed silica slurry, the cutting rate and the polishing rate during polishing of the substrate can be significantly reduced while maintaining a level equal to or higher than that of the conventional case.

The contact angle measurement is performed at room temperature, and the fumed silica slurry has a pH of 10.5 and an average particle size of 150 nm, based on which 12 wt% of fumed silica is dispersed. In addition, since the specific composition and manufacturing method of the fumed silica slurry serving as a reference for measuring the contact angle overlap with those described above, description thereof is omitted.

The contact angle measured by the fumed silica slurry of the polishing pad 100 may be 85 to 120 º.

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

The difference between the contact angle of the polishing pad 100 and the contact angle measured by the fumed silica slurry may be 1.5 º or more, 1.8 º or more, and 2º or more.

The polishing pad 100 may have a difference between a contact angle with respect to pure water and a contact angle measured with a fumed silica slurry, and may be 1.2 to 5 º, and may be 1.5 to 4 º.

As mentioned 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 the fumed silica slurry may increase the repulsive force between the surface of the polishing pad and the slurry particles when it comes into contact with the polishing slurry. It is possible to significantly reduce the phenomenon that the slurry particles are fixed on the abrasive mat, which allows to obtain excellent polishing quality.

The polishing pad 100 having a relatively large contact angle difference with the slurry described above has a larger defect reduction effect when it is a foamed pad. This often creates defects on the surface of the polished substrate when particles contained in the slurry are introduced and fixed to the fine pores located on the surface of the foamed polishing pad. I think it is because it can be reduced.

In the present invention, by including a silane-based repeating unit on the main chain of the polyurethane constituting the polishing pad 100, in particular to induce a greater repulsive force between the silica particles and the polyurethane surface, polishing the polishing pad using a slurry Rate, cutting rate, etc. are maintained at the same level or more, and the degree of defect occurrence is significantly reduced.

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

The top pad 10 is a pad made of polyurethane in the form of a foam having the characteristics described above, and may have an average pore size of 10 to 30 mm. It is good to apply the top pad having the average pore size to improve the polishing efficiency of the polishing pad.

The top pad 10 may be polyurethane in the form of a foam having an area ratio of 36 to 44%. The top pad 10 may be a polyurethane in the form of a foam having a pore number per unit area of 350 to 500. Efficient wafer polishing is possible when the polyurethane top pad 10 in the form of a foam having this feature is applied.

The top pad 10 may have a Shore D hardness of 55 to 65, and in this case, the polishing efficiency may be increased.

The top pad 10 may have a thickness of 1.5 to 3 mm, and in this case, polishing efficiency may be increased.

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

The sub pad 30 may be of a non-woven type or a sweat type.

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

The top pad 10 and the sub pad 30 may be attached through a hot melt adhesive layer 15.

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

The second adhesive layer of the rubber-based adhesive 35 located on the other surface of the subpad 30 may have a film 50 such as a PET film 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 may be adhered to the surface of the polishing machine through a rubber-based adhesive (35, second adhesive layer).

The polishing pad 100 according to another embodiment of the present invention includes a top pad (10), which is a polyurethane-based polishing layer comprising a foam of a urethane composition comprising a urethane-based prepolymer, a curing agent, and a blowing 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 repeating unit.

The silane-based compound is a compound capable of introducing a silane-based repeating unit into the main chain of urethane by reacting with an isocyanate such as a silane-modified polyol or a silane-modified amine. Specifically, the silane-based compound may include a silane-based repeating unit represented by Chemical Formula 1 below, and at least one terminal may be a silane-based compound including a hydroxy group, an amine group, or an epoxy group.

[Formula 1]

In Formula 1, the detailed description of R ₁₁ , R ₁₂ , and n is redundant with that described above, and thus description thereof is omitted.

The silane-based compound may be included in an amount of 0.1 to 5% by weight, 1 to 3% by weight, and 1.5 to 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 total amount of the prepolymer composition, a defect reduction effect due to the content of the silane-based compound may be negligible, and when it exceeds 5% by weight, gelation is performed in the synthetic process. Synthesis can be difficult to occur and have the intended properties. When the silane-based compound is included in the content, a polyurethane polishing pad having an excellent defect reduction effect may be provided.

Specifically, the top pad 10 can reduce the defect level of the polished silicon wafer by 80% or more, as compared with a foamed polyurethane that does not include the silane repeating unit represented by Chemical Formula 1, It can be reduced by over 85%, and can be reduced by over 90%. The degree of defect reduction is a value obtained at a level equivalent to that of the existing cutting rate, polishing rate, etc., and can significantly reduce the defect rate of the silicon wafer due to defects.

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

[Formula 3]

In Formula 3, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen, 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), wherein R ₃₁ is an alkylene group having 1 to 20 carbon atoms, and R ₄₁ and R ₄₂ are each independently As, hydroxy group, amine group, or epoxy group, n is an integer of 1 to 30.

Specifically, in Formula 3, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently hydrogen, 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- (where m1, m2, and m3 are each independently an integer of 2 to 12), wherein R ₃₁ is an alkylene group having 1 to 10 carbon atoms, and R ₄₁ and R ₄₂ Each independently represents a hydroxy group, an amine group, or an epoxy group, and n is an integer from 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- (where m1, m2, and m3 are each independently an integer of 2 to 12), wherein R ₃₁ is an alkylene group having 1 to 5 carbon atoms, and R ₄₁ and R ₄₂ are each Independently, it is a hydroxy group, an amine group, or an epoxy group, and n is an integer from 10 to 25.

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

The alcohol compound may include at least one polyol compound or a single molecule alcohol compound.

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 single-molecule alcohol compound may be any one selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, methyl propanediol, and combinations thereof, but is not limited thereto.

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

The prepolymer composition may include the alcohol compound in an amount of 0.7 to 1.3 parts by weight based on 1 part by weight of the isocyanate compound, and may include 0.05 to 7% by weight of the silane compound. Specifically, the prepolymer composition may contain 0.8 to 1.2 parts by weight of the alcohol compound based on 1 part by weight of the isocyanate compound, and may include 0.1 to 5% by weight of the silane compound. More specifically, the prepolymer composition may include the alcohol compound in an amount of 0.85 to 1.15 parts by weight based on 1 part by weight of the isocyanate compound, and may include 1.6 to 2.5% by weight of the silane compound. When the prepolymer composition is configured in this range, a polyurethane having physical properties more suitable for a polishing pad may be prepared.

The prepolymer may be that the NCO weight% is 8 to 12% by weight. When having NCO weight% in this range, a porous polyurethane pad in the form of a foam having appropriate hardness can be prepared.

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

The amine curing agent may be any one selected from the group consisting of 4,4'-methylenebis(2-chloroaniline), m-phenylene diamine, diethyltoluenediamine, hexamethylenediamine, and combinations thereof.

For the foaming agent, a gas-phase foaming agent, a solid-phase foaming agent, a liquid foaming agent, and combinations thereof may be applied.

As the gaseous foaming agent, an inert gas may be specifically applied, for example, nitrogen gas, carbon dioxide gas, or the like.

As the solid foaming agent, an organic hollow sphere and/or an inorganic hollow sphere may be applied, and for example, a microsphere encapsulating a hydrocarbon gas into a polymer may be applied.

As the liquid foam, a galdenic solution (Tri perfluoro propyl amine), liquid carbon dioxide, liquid hydrofluorocarbon, etc. may be applied, but is not limited thereto.

The urethane composition may further include a surfactant. The surfactant may be applied with a nonionic surfactant or an ionic surfactant, and at least one block comprising polydimethylsiloxane and at least another block comprising polyether, polyester, polyamide, or polycarbonate segments. Silicone surfactants such as copolymers containing one may be applied, but are not limited thereto.

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 based on 100 parts by weight of the urethane-based prepolymer. In addition, when the foam is applied as a gas-phase foaming agent, the discharge rate may be applied at 0.1 to 2.0 L/min. When the urethane composition is constituted in this ratio, polyurethane in the form of a foam having physical properties suitable for a polishing pad may be formed.

Method for producing a urethane prepolymer for a polishing pad according to another embodiment of the present invention includes an isocyanate compound, an alcohol compound, and a silane repeating unit represented by Chemical Formula 1, and at least one terminal includes a hydroxy group, an amine group, or an epoxy group. It comprises; a prepolymer preparation step of preparing a urethane prepolymer having 8 to 12% by weight of NCO by reacting a prepolymer composition containing a silane-based compound at 50 to 120°C.

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

The detailed description of the isocyanate compound, the alcohol compound, the silane-based compound, the prepolymer composition, and the like is redundant with the above description, and thus the description thereof will be omitted.

Method of manufacturing a polishing pad 100 according to another embodiment of the present invention, i) a urethane composition containing a urethane prepolymer for a polishing pad, a curing agent, and a blowing agent is mixed and then subjected to a polymerization reaction to be represented by Formula 1 Polyurethane forming process of forming a polyurethane in the form of a foam containing a repeating silane-based unit; ii) a top pad manufacturing process for manufacturing the top pad 10 comprising the polyurethane; And iii) a lamination process of manufacturing a polishing pad by bonding the top pad with a sub pad; including, a polyurethane polishing pad 100 including a silane repeating unit represented by Formula 1 in the main chain To prepare.

The detailed description of the isocyanate compound, the alcohol compound, the silane-based compound, the prepolymer composition, the urethane composition, and the like is duplicated with the above description, so that description is omitted.

A method for manufacturing a polished wafer according to another embodiment of the present invention includes a preparation step of mounting the polishing pad 100 and the wafer before polishing to the CMP polishing apparatus; And a polishing step of preparing a polished wafer by grinding the wafer before polishing using the polishing pad while inputting a polishing slurry to the CMP polishing apparatus.

The pre-polishing wafer may be specifically a silicon wafer, for example, a silicon wafer on which silicon oxide is deposited.

The polishing slurry may be a polishing slurry including fumed silica, colloidal silica, ceria, and the like.

The polishing may be performed by pressing the wafer and/or the polishing pad to contact each other before polishing, and the pressing may be applied at 1 to 7 psi.

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

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

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

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

In the method of manufacturing the polished wafer, the polishing pad of the present invention can be applied to produce an excellent polishing rate, cutting rate, and the like, and a polishing pad having a low defect count.

Hereinafter, the present invention will be described in more detail.

1. Preparation of polishing pad

Preparation of sheet for top pad of Example 1

As a isocyanate compound, TDI (Toluene Diisocyanate) and a polyol compound, PTMEG (Polytetramethylene ether glycol) and Diethylene glycol (Diethylene glycol) were introduced into a four-necked flask and reacted at 80°C for 3 hours to react the primary reactant. Got. The primary reactant and the silane-modified polyol (Wacker®IM11, Mw:1000) were placed in a four-necked flask and reacted at 80° C. for 2 hours to prepare a prepolymer having 8 to 12% by weight of NCO (prepolymer). At this time, the silane-modified polyol was applied 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 prepared above, and the curing agent tank contains bis(4-amino-3-chlorophenyl)methane [Bis( 4-amino-3-chlorophenyl)methane, Ishihara Co.]. Nitrogen gas (N ₂ ) was prepared as an inert gas. The solid foaming agent (Akzonobel Co.) and silicone surfactant (Evonik Co.) were mixed in separate lines or mixed with the prepolymer.

In the casting machine thus prepared, the equivalent weight of the prepolymer and the curing agent was adjusted to 1:1, and then discharged at a rate of 10 kg per minute. At this time, the amount of the inert gas nitrogen (N ₂ ) was injected at the rate indicated in Table 1 below compared to the total flow volume.

After mixing the raw materials injected at high speed from the mixing head, the injectable gas is injected into a mold having a width of 1000 mm, a height of 1000 mm, and a height of 3 mm, the specific gravity is 0.8 to 0.9 g/cc, and the pores are The top pad sheet 10 of the present Example 1 was obtained.

Preparation of sheet for top pad of Example 2

As a isocyanate compound, TDI (Toluene Diisocyanate) and a polyol compound, PTMEG (Polytetramethylene ether glycol) and Diethylene glycol (Diethylene glycol) were introduced into a four-necked flask and reacted at 80°C for 3 hours to react the primary reactant. Got. The primary reactant and the silane-modified polyol (Wacker®IM22, Mw:2000) were placed in a four-necked flask and reacted at 80° C. for 2 hours to prepare a prepolymer having 8 to 12% by weight of NCO (prepolymer). At this time, the silane-modified polyol was applied 2% by weight based on the total prepolymer.

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

Preparation of the top pad sheet of Comparative Example 1

As isocyanate compound, TDI (Toluene Diisocyanate) and polyol compound PTMEG (Polytetramethylene ether glycol) and diethylene glycol (Diethylene glycol) were added to a four-necked flask and reacted at 80° C. to produce an NCO weight% of 8 to 12 A prepolymer of weight percent was prepared and the following procedure was performed.

A top pad sheet of Comparative Example 1 was prepared in the same manner as in Example 1, except that the prepolymer prepared in Comparative Example 1 above was applied.

Application amount during casting Example 1 Example 2 Comparative Example 1 Prepolymer (parts by weight) 100 100 100 Hardener (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) 0.5~1.5 0.5~1.5 0.5~1.5

Preparation of polishing pad

The sheet 10 for the top pad manufactured above was sequentially made through a surface milling and grooving process in a conventional manner, and was manufactured as a polishing pad 100 having the structure shown in FIG. 1 through a sub pad 30 laminating process. .

2. Evaluation of properties of polishing pad

Strength and contact angle evaluation

Using the polishing pads of Example 1, Example 2 and Comparative Example 1 prepared above, physical properties were evaluated, such as measuring the contact angle of the fumed silica slurry, evaluating the CMP polishing performance, and measuring the number of defects in the wafer. .

As for the contact angle, the center of the groove without the groove of the manufactured polishing pad was collected with a width of 2x2 cm, and this specimen was measured using a contact angle analyzer (Dynamic Contact Angle Analyzer, model name: DCA-312, manufacturer: CAHN). .

After the specimens of Examples 1 and 2 and Comparative Examples were mounted on the above measuring instrument, each syringe was filled with pure (H ₂ O) and fumed silica slurry (Fumed silica Slurry), and then injected with an appropriate amount on the specimen, and The shape was evaluated by measuring using a contact angle meter. The composition and manufacturing process of the fumed silica slurry will be described separately.

Preparation of fumed silica slurry

A pH = 10.5 solution consisting of a first pH modifier (ammonia, potassium hydroxide, sodium hydroxide, etc.) and ultrapure water was prepared. About 12% by weight of fumed silica (Fumed silica, OCI) using an ultra sonicator at a speed of 9000 rpm was dispersed in small amounts. After the dispersion process of about 4 hours, an additional dispersion operation was performed through a high pressure disperser.

After the sufficient dispersion process proceeded, 0.5 to 2% by weight of the ammonium-based additive was added to further agitate for 1 hour. Thereafter, 0.01 to 0.1% by weight of a nonionic surfactant was added and the pH of the solution was adjusted to a level of 10.5 using a second pH adjusting agent (ammonia, potassium hydroxide, sodium hydroxide, nitric acid, sulfonic acid, etc.).

The final fumed silica slurry was obtained by filtration using a filter for a slurry (micropore) having a pore size of 3.5 um and 1 um. The physical properties of the final slurry were pH = 10.5, particle size = 150 nm (nano-ZS 90, malvern).

In addition to the physical properties of the top pad prepared above, the physical properties of the entire sub-pad and the polishing pad are also shown in Table 2 below.

division Evaluation item Example 1 Example 2 Comparative Example 1 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 (N/mm ² ) 21.1 20.9 20.8 Elongation (%) 126 125 123 Hardness by Temperature_Shore D
(30℃/50℃/70℃) 58/54/51 58/54/51 58/54/51 Contact angle Ap (º, H ₂ O) 90 89 71 Contact angle Af (º, Fumed silica slurry) 88 86 70 Contact angle difference* 2.22% 3.37% 1.41%
Sub pad Kinds Non-woven Non-woven Non-woven 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 rate (%) 1.05 1.05 1.05

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

Referring to the results of Table 2 above, the characteristics of Comparative Example 1 and Examples 1 and 2 were similar in hardness, average pore size, specific gravity, etc., but for pure water and fumed silica slurry. It was confirmed that there was a significant difference in the contact angle.

Evaluation of the pore properties of the top pad

After the pores of the top pad were photographed at 100x magnification by SEM (JEOL), the quantity, size, and area ratio were measured, and the results are shown in FIG. 2 and Table 3 below.

Top pad pore properties Example 1 Example 2 Comparative Example 1 Number average diameter (um) 28.3 26.8 28 Quantity / 0.3 cm ² (ea) 412 405 402 Area rate (%) 40.1 40 39.8

Evaluation of polishing properties

Using the polishing pads of Example 1, Example 2 and Comparative Example 1 prepared above, the removal rate (removal rate), the cutting rate of the polishing pad (pad cut-rate, μm/hr), defects of the polished wafer , Defect) was measured by the following method.

1) Measurement of polishing rate

After installing a silicon wafer of 300 mm in diameter with silicon oxide deposited by a CVD process using a CMP polishing equipment, the silicon oxide layer of the silicon wafer was placed down to attach the porous polyurethane polishing pad. Was set on. Thereafter, the polishing load was adjusted to be 4.0 psi, and while rotating the polishing pad at 150 rpm, the calcined ceria slurry was put on the polishing pad at a rate of 250 ml/min, and the platen was rotated at 150 rpm for 60 seconds to polish the silicon oxide film. . After polishing, the silicon wafer was removed from the carrier, mounted on a spin dryer, washed with purified water (DIW), and dried with nitrogen for 15 seconds. The dried silicon wafer was measured for change in film thickness before and after polishing using an optical interference thickness measuring device (manufacturer: Kyence, model name: SI-F80R).

The polishing rate was calculated using Equation 2 below.

(Equation 2)

Polishing rate = Silicon wafer polishing thickness (Å) / polishing time (60 seconds)

2) Measurement of cutting rate

Each of the prepared polishing pads was pre-conditioned with deionized water for the first 10 minutes, and then conditioned with deionized water sprayed for 1 hour. At this time, the thickness change was measured during conditioning for 1 hour.

The equipment used for conditioning was CTS' AP-300HM, the conditioning pressure was 6 lbf, the rotational speed was 100 to 110 rpm, and the disc used for conditioning was Sasol LPX-DS2.

3) Defect measurement

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

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

The dried silicon wafer was measured for defect change before and after polishing using a defect measurement device (manufacturer: Tenkor, model name: XP+).

The measurement results of the polishing rate, the cutting rate and the number of defects are shown in Table 4 and FIGS. 3 and 4 below.

Example 1 Example 2 Comparative example RR (Å/min) 2733 2754 2759 Number of defects (#Defect, dog) 7 5 50 Cutting rate (㎛/hr) 51 53 50 Defect reduction rate compared to Comparative Example (%)* 86% 90% -

* Defect reduction rate (%) is a value calculated by "[(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 Example 1 and Example 2 significantly reduced the number of defects of the polished wafer while the polishing rate and cutting rate were similar to those of the comparative example.

The preferred embodiments of the present invention have been described in detail above, but the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

100: polishing pad
10: top pad, polishing layer 15: first adhesive layer
30: bottom pad, sub pad 35: second adhesive layer
50: film 55: third adhesive layer

Claims (15)

i) a polishing pad comprising polyurethane containing a silane repeating unit represented by the following Chemical Formula 2-1 or Chemical Formula 2-2 in the main chain, ii) defects on the substrate polished with the polishing pad and fumed silica slurry 25 It has a low-defect property of less than, and iii) 0.1 to 5% by weight of a silane repeating unit represented by Chemical Formula 2-1 or Chemical Formula 2-2, and iv) the contact angle difference according to Formula 1 below A polishing pad having a value (Ad _(pf) , %) of 1.5 to 5;
[Formula 2-1]

[Formula 2-2]

In Chemical Formulas 2-1 and 2-2,
R ₁₁ and R ₁₂ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms,
R ₂₁ is -Si(R ₁₃ )(R ₁₄ )(R ₂₂ )-, 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 - , and (where, m1, m2 and m3 is an integer of 1 to 20, each independently),
N is an integer from 1 to 30,
[Equation 1]
Ad _(pf) = [100*(Ap-Af)]/Ap
In the above formula 1,
The Ap is a contact angle measured with pure water,
The Af is a contact angle measured with a fumed silica slurry.
delete delete According to claim 1,
The polyurethane is in the form of a foam, the average pore size of the foam is 10 to 30 μm, a polishing pad.
According to claim 1,
The polyurethane has a Shore D hardness of 55 to 65, a polishing pad.
According to claim 1,
The polishing pad includes a top pad comprising the polyurethane and a non-woven fabric or suede type subpad located on one surface of the top pad.
delete delete delete delete delete i) Poly to form a polyurethane in the form of a foam comprising a silane repeating unit represented by Formula 2-1 or Formula 2-2 below by mixing a urethane composition containing a urethane prepolymer, a curing agent, and a foaming agent, and then performing a polymerization reaction. Urethane formation process; ii) a top pad manufacturing process for manufacturing a top pad comprising the polyurethane; And iii) a lamination process of manufacturing the polishing pad by adhering the top pad with a sub pad.
The silane-based repeating unit represented by the following Chemical Formula 2-1 or Chemical Formula 2-2 is included in the main chain in an amount of 0.1 to 5% by weight, and the contact angle difference value (Ad _(pf) , %) according to the following Formula 1 is 1.5 to 5, A method for manufacturing a polyurethane polishing pad, the manufacturing method of the polishing pad;
[Formula 2-1]

[Formula 2-2]

In Chemical Formulas 2-1 and 2-2,
R ₁₁ and R ₁₂ are each independently hydrogen or an alkyl group having 1 to 10 carbon atoms,
R ₂₁ is -Si(R ₁₃ )(R ₁₄ )(R ₂₂ )-, 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 - , and (where, m1, m2 and m3 is an integer of 1 to 20, each independently),
N is an integer from 1 to 30,
[Equation 1]
Ad _(pf) = [100*(Ap-Af)]/Ap
In the above formula 1,
The Ap is a contact angle measured with pure water,
The Af is a contact angle measured with a fumed silica slurry.
delete delete Preparatory steps for mounting the polishing pad according to claim 1 and the pre-abrasive wafer to a CMP polishing apparatus: and while polishing the wafer before polishing using the polishing pad while injecting polishing slurry into the CMP polishing apparatus, the polished wafer Polishing step of manufacturing; comprising, a method of manufacturing a polished wafer.

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