JP7565682B2 - Method for manufacturing polishing pad and polished product - Google Patents

Description

The present invention relates to a method for manufacturing a polishing pad and a polished workpiece.

In the semiconductor manufacturing process, chemical mechanical polishing (CMP) is used for planarization after insulating film deposition and for forming metal wiring. One of the important technologies required for chemical mechanical polishing is polishing end point detection, which detects whether the polishing process is complete. For example, over-polishing or under-polishing relative to the target polishing end point directly leads to product defects. For this reason, in chemical mechanical polishing, the amount of polishing must be strictly controlled by polishing end point detection.

Chemical mechanical polishing is a complex process, and the polishing speed (polishing rate) changes depending on the operating conditions of the polishing equipment, the quality of consumables (slurry, polishing pads, dressers, etc.), and variations in conditions over time during the polishing process. Furthermore, in recent years, the precision of remaining film thickness and in-plane uniformity required in semiconductor manufacturing processes have become increasingly strict. For these reasons, it has become more difficult to detect the polishing end point with sufficient precision.

The main methods known for detecting the polishing end point are the optical end point detection method, the torque end point detection method, and the eddy current end point detection method.

In the optical end point detection method, light is irradiated onto the wafer through a transparent window member installed on the polishing pad, and the reflected light is monitored to detect the end point. However, slurry may leak from around the window member during polishing, which may reduce the detection accuracy. In addition, it is necessary to install a window member made of a different material and with different physical properties on the polishing pad, which can cause problems such as uneven polishing in the area where the window member is installed.

In addition, in the eddy current endpoint detection method, the endpoint is detected using eddy currents that are generated in a conductive film on the wafer surface when magnetic lines pass through the conductive film. Known polishing pads used in this type of eddy current endpoint detection method include a polishing pad with a recess on the back surface of the polishing layer to accommodate the drive and sensing coils (Patent Document 1), and a polishing pad with an endpoint detection area formed in the polishing body from a material different from the polishing body and recessed from the back surface of the polishing body (Patent Document 2).

Special Publication No. 2005-533667 Special Publication No. 2013-539233

As described above, the polishing pads disclosed in Patent Documents 1 and 2 all have a recess or a recessed portion in the area (hereinafter also referred to as the "end point detection area") that corresponds to the film thickness detection sensor (coil). Therefore, the polishing pressure applied to the workpiece in the end point detection area differs from the polishing pressure applied to the workpiece on the polishing surface other than the end point detection area, resulting in a problem of loss of in-plane uniformity of polishing.

In addition, the invention described in Patent Document 2 provides an end point detection area that is a separate member from the polishing layer, which can cause slurry to leak from around the separate member, potentially reducing detection accuracy.

The present invention was made in consideration of the above problems, and aims to provide a polishing pad that can be used for highly accurate eddy current end point detection while maintaining appropriate polishing performance, and a method for manufacturing polished products using the same.

As a result of extensive research into solving the above problems, the inventors discovered that the above problems could be solved by adjusting the magnetic permeability in the thickness direction, which led to the completion of the present invention.

That is, the present invention is as follows.
[1]
A polishing layer and a base layer laminated on the polishing layer,
The magnetic permeability μ _all in the thickness direction is 2.52×10 ⁻⁶ to 1.26×10 ⁻⁴ H/m.
Polishing pad.
[2]
The magnetic permeability μ ₁ in the thickness direction of the polishing layer is 1.26×10 ⁻⁶ to 1.26×10 ⁻⁵ H/m.
The polishing pad according to [1].
[3]
The magnetic permeability μ ₂ in the thickness direction of the base layer is 1.26×10 ⁻⁶ to 3.78×10 ⁻⁴ H/m.
The polishing pad according to [1] or [2].
[4]
The method includes a polishing step of polishing a workpiece using the polishing pad according to any one of [1] to [3] to obtain a polished product, and an end point detection step of detecting an end point during the polishing by an eddy current method.
A method for manufacturing polished workpieces.

The present invention provides a polishing pad that can be used for highly accurate eddy current end point detection while maintaining appropriate polishing performance, and a method for manufacturing a polished product using the same.

1 is a schematic cross-sectional view of a polishing pad according to an embodiment of the present invention. FIG. 1 is a schematic diagram showing a film thickness control system installed in CMP. FIG. 2 is a schematic diagram showing the measurement principle of eddy current type endpoint detection.

The following describes in detail an embodiment of the present invention (hereinafter referred to as the "present embodiment"); however, the present invention is not limited to this embodiment, and various modifications are possible without departing from the gist of the present invention.

[Polishing pad]
The polishing pad of this embodiment has a polishing layer and a base layer laminated on the polishing layer, and has a magnetic permeability μ _all in the thickness direction of the pad of 2.52×10 ⁻⁶ to 1.26×10 ⁻⁴ H/m.

The magnetic permeability μ _all in the thickness direction of the polishing pad of this embodiment is 2.52×10 ⁻⁶ to 1.26×10 ⁻⁴ H/m, preferably 3.15×10 ⁻⁶ to 6.30×10 ⁻⁵ H/m, and more preferably 3.78×10 ⁻⁶ to 1.26×10 ⁻⁵ H/m. Conventionally known polishing pads are formed from polymeric materials such as polyurethane, which are paramagnetic materials, and have a low magnetic permeability of about 1.26×10 ⁻⁶ H/m, and the accuracy of eddy current end point detection is not very good. On the other hand, the magnetic permeability μ _all of the present invention is within the above range, so that the accuracy of eddy current end point detection tends to be improved. Methods for adjusting the magnetic permeability μ _all include a method of including magnetic particles in the base layer, which will be described later, a method of providing a magnetic permeable layer including a magnetic material between the polishing layer and the base layer and/or on the surface of the base layer opposite to the surface in contact with the polishing layer, and a method of including a conductive polymer in the polishing layer, etc.

As shown in FIG. 1, the polishing pad 10 of this embodiment has a polishing layer 11 and a base layer 12 whose thickness is the same in the end point detection area as in other areas. Therefore, compared to cases where, for example, a recess or a recessed portion is used, it is possible to maintain the desired polishing performance, such as ensuring uniformity of the polishing surface and suppressing leakage of slurry, and it is possible to provide a polishing pad that can be used for highly accurate eddy current end point detection while maintaining appropriate polishing performance. The detailed configuration is described below.

[Polishing layer]
The polishing layer 11 has a polishing surface 11a for polishing an object to be polished. The configuration of the polishing layer is not particularly limited, and examples thereof include a foamed resin molded body, a non-foamed resin molded body, and a resin-impregnated substrate.

Here, a resin foamed molded body refers to a foamed body that does not have a fiber base material and is composed of a specific resin. There are no particular limitations on the foam shape, but examples include spherical bubbles, nearly spherical bubbles, teardrop-shaped bubbles, and open bubbles in which each bubble is partially connected.

In addition, the term "non-foamed resin molded body" refers to a non-foamed body that does not have a fiber substrate and is composed of a specific resin. The term "non-foamed body" refers to a body that does not have bubbles as described above. In this embodiment, the term "non-foamed resin molded body" also includes a body in which a curable composition is attached to a substrate such as a film and cured. More specifically, the term "non-foamed resin molded body" also includes a cured resin product formed by a labia coater method, small diameter gravure coater method, reverse roll coater method, transfer roll coater method, kiss coater method, die coater method, screen printing method, spray coating method, etc.

Furthermore, a resin-impregnated substrate is one obtained by impregnating a fiber substrate with a resin. Here, the fiber substrate is not particularly limited, but examples thereof include woven fabric, nonwoven fabric, knitted fabric, etc.

(resin)
The resin constituting the polishing layer may be a wet-solidifiable resin, a dry-solidifiable resin, or other curable resin, etc. These resins may be used alone or in combination of two or more kinds.

Here, "wet coagulation" refers to a method in which a fiber substrate is impregnated with a resin solution in which resin has been dissolved, and the fiber substrate is immersed in a bath of a coagulation liquid (such as water, which is a poor solvent for the resin), thereby coagulating and regenerating the resin in the impregnated resin solution. Alternatively, a resin solution in which resin has been dissolved may be applied to a film or the like, and the film may be immersed in a bath of the coagulation liquid to obtain a resin molded body that does not contain a fiber substrate. In this wet coagulation, the solvent in the resin solution is replaced with the coagulation liquid, causing the resin in the resin solution to coagulate and coagulate. Note that air bubbles are formed in areas other than where the resin has coagulated and coagulated. There are no particular restrictions on the shape of the air bubbles that are formed, but they tend to be teardrop-shaped.

"Dry coagulation" refers to a method in which a liquid containing a prepolymer and a hardener is impregnated into a fiber substrate, and the prepolymer and hardener are reacted to form a resin. Alternatively, a liquid containing a prepolymer and a hardener may be applied to a film or the like, and the prepolymer and hardener are reacted to obtain a molded resin body that does not contain a fiber substrate. In this wet coagulation, a foam is obtained when gas is generated by the reaction between the prepolymer and the hardener or when a foaming agent is used, and a non-foamed body is obtained in other cases. The shape of the foam is not particularly limited, but it tends to be spherical or approximately spherical.

Specific examples of each resin are given below, but the resins that make up the polishing layer of this embodiment are not limited to the following.

Examples of resins that can be wet-solidified include, but are not limited to, polyurethane-based resins such as polyurethane and polyurethane polyurea; acrylic-based resins such as polyacrylate and polyacrylonitrile; vinyl-based resins such as polyvinyl chloride, polyvinyl acetate and polyvinylidene fluoride; polysulfone-based resins such as polysulfone and polyethersulfone; acylated cellulose-based resins such as acetylated cellulose and butyrylated cellulose; polyamide-based resins; and polystyrene-based resins.

Among these, it is preferable to include a polyurethane-based resin. Examples of polyurethane-based resins include, but are not limited to, polyester-based polyurethane resins, polyether-based polyurethane resins, and polycarbonate-based polyurethane resins. By using such resins, the polishing rate tends to be further improved.

Prepolymers constituting the dry-solidifiable resin are not particularly limited, but examples include an adduct of hexamethylene diisocyanate and hexanetriol; an adduct of 2,4-tolylene diisocyanate and polyoxytetramethylene glycol; an adduct of tolylene diisocyanate and hexanetriol; an adduct of tolylene diisocyanate and trimethylolpropane; an adduct of xylylene diisocyanate and trimethylolpropane; an adduct of hexamethylene diisocyanate and trimethylolpropane; and an adduct of isocyanuric acid and hexamethylene diisocyanate. One type of prepolymer may be used alone, or two or more types may be used in combination.

The curing agent constituting the dry-solidifying resin is not particularly limited, but examples thereof include amine compounds such as 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4-methyl-2,6-bis(methylthio)-1,3-benzenediamine, 2-methyl-4,6-bis(methylthio)-1,3-benzenediamine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2,2-bis[3-(isopropylamino)-4-hydroxyphenyl]propane, 2,2-bis[3-(1-methylpropylamino)-4-hydroxyphenyl]propane, 2,2-bis[3-(1-methylpentylamino)-4-hydroxyphenyl]propane, 2,2-bis(3,5-diamino-4-hydroxyphenyl)propane, 2,6-diamino-4-methylphenol, trimethylethylenebis-4-aminobenzoate, and polytetramethylene oxide-di-p-aminobenzoate; ethylene glycol, propylene glycol, and the like. Examples of polyhydric alcohol compounds include ethylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, trimethylolpropane, trimethylolethane, and trimethylolmethane. The curing agent may be used alone or in combination with two or more types.

The composition constituting the other curable resin is not particularly limited, but may be, for example, a photocurable composition containing a photopolymerization initiator and a polymerizable compound, a thermosetting composition containing a thermal polymerization initiator and a polymerizable compound, a thermosetting resin, a UV-curable resin, or a two-liquid mixed curable resin. In addition, the curable composition may contain a crosslinking agent having two or more polymerizable functional groups, if necessary.

The above polymerizable compound is not particularly limited, but examples thereof include (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate.

The photopolymerization initiator is not particularly limited, but examples thereof include benzophenone-based compounds, acetophenone-based compounds, and thioxanthones. In addition, the thermal polymerization initiator is not particularly limited, but examples thereof include azo compounds such as 2,2'-azobisbutyronitrile, and peroxides such as benzoyl peroxide (BPO).

The above-mentioned thermosetting resins are not particularly limited, but examples thereof include phenolic resins, epoxy resins, acrylic resins, urea resins, and formaldehyde resins.

The above-mentioned UV-curable resin is not particularly limited, but examples thereof include prepolymers with a number average molecular weight of about 1,000 to 10,000, acrylic (methacrylic) esters and their urethane modifications, thiokol-based compounds, etc., and reactive diluents and organic solvents can be used as appropriate depending on the application.

The two-liquid mixed curable resin is not particularly limited, but for example, prepolymers with different physical properties can be used.

(Magnetic permeability μ ₁ )
The magnetic permeability _μ1 of the polishing layer in the thickness direction is preferably 1.26×10 ^-6 to 1.26×10 ^-5 H/m, more preferably 1.26×10 ^-6 to 6.30×10 ^-6 H/m, and even more preferably 1.26×10 ^-6 to 3.78×10 ^-6 H/m. With the magnetic permeability _μ1 within the above range, the accuracy of eddy current type endpoint detection tends to be further improved.

The method of adjusting the magnetic permeability _μ1 of the polishing layer includes a method of including a conductive polymer in the polishing layer. The conductive polymer is not particularly limited, but includes, for example, polythiophene, polyaniline, polypyrrole, etc. By including such a conductive polymer, the accuracy of eddy current end point detection tends to be improved.

The content of the conductive polymer is preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight, and even more preferably 0.1 to 3% by weight, relative to the total amount of resin forming the polishing layer. By having the conductive polymer content within the above range, the accuracy of eddy current end point detection tends to be further improved. In addition, by having the conductive polymer content be 10% by weight or less, changes in the resin properties of the polishing layer due to the addition of the conductive polymer tend to be further suppressed.

In addition, one method of adjusting the magnetic permeability _μ1 of the polishing layer is to include magnetic particles in the polishing layer. However, since the polishing layer comes into direct contact with the workpiece, particularly in polishing semiconductors, it is preferable not to include magnetic particles since the magnetic particles may adversely affect the semiconductor.

[Base layer]
The polishing pad of this embodiment has a base layer on the opposite side of the polishing surface of the polishing layer. By having the base layer, the conformability to the workpiece to be polished is improved, and the uniformity of the polishing pressure on the workpiece tends to be improved.

The substrate layer is not particularly limited, but examples thereof include impregnated nonwoven fabrics and resin foams impregnated with resin. Examples of impregnated nonwoven fabrics include polyolefin-based, polyamide-based, polyester-based, and other nonwoven fabrics impregnated with polyurethane-based materials such as polyurethane and polyurethane polyurea, acrylic-based materials such as polyacrylate and polyacrylonitrile, vinyl-based materials such as polyvinyl chloride, polyvinyl acetate, and polyvinylidene fluoride, polysulfone-based materials such as polysulfone and polyethersulfone, acylated cellulose-based materials such as acetylated cellulose and butyrylated cellulose, polyamide-based, and polystyrene-based resins. Examples of resin foams include polyolefin-based foams, polyurethane-based foams, polystyrene-based foams, phenol-based foams, synthetic rubber-based foams, and silicone rubber-based foams.

(Magnetic permeability _μ2 )
The magnetic permeability _μ2 in the thickness direction of the base layer is preferably 1.26× ^10-6 to 3.78× ^10-4 H/m, more preferably 3.78× ^10-6 to 1.26× ^10-4 H/m, and even more preferably 1.26× ^10-5 to 6.30× ^10-5 H/m. By having the magnetic permeability _μ2 within the above range, the accuracy of eddy current type endpoint detection tends to be further improved.

The method of adjusting the magnetic permeability _μ2 of the base layer includes a method of including magnetic particles in the base layer. The magnetic particles are not particularly limited, but include, for example, soft magnetic bodies with small coercive force and large magnetic permeability, hard magnetic bodies with large coercive force, and magnetic resistors whose electrical resistance changes when a magnetic field is applied. Among these, soft magnetic bodies such as soft ferrite, permalloy, and silicon steel are preferred. By using such magnetic particles, the accuracy of eddy current end point detection tends to be further improved. Unlike the polishing layer, the base layer does not directly contact the polished object, so even if magnetic particles are included, there is a low possibility that they will adversely affect polishing.

The content of the magnetic particles is preferably 0.01 to 30% by weight, more preferably 0.05 to 20% by weight, and even more preferably 0.1 to 10% by weight, relative to the total weight of the base layer. With the content of the magnetic particles within the above range, the accuracy of eddy current end point detection tends to be improved. The average particle size of the magnetic particles is preferably 3.5 to 200 μm, more preferably 5 to 150 μm, and even more preferably 10 to 100 μm.

[Magnetic permeable layer]
In order to adjust the magnetic permeability μ _all in the thickness direction of the polishing pad, it is also possible to provide a magnetic permeable layer containing a magnetic material between the polishing layer and the base layer and/or on the surface of the base layer opposite to the surface in contact with the polishing layer.

The magnetic material used in the magnetic permeable layer is not particularly limited, but examples include soft magnetic materials with small coercive force and large magnetic permeability, hard magnetic materials with large coercive force, and magnetic resistors whose electrical resistance changes when a magnetic field is applied. Among these, soft magnetic materials such as soft ferrite, permalloy, and silicon steel are preferable.

The magnetically permeable layer may be in the form of a sheet made of only these magnetic materials, or may be in the form of a sheet made by dispersing the magnetic materials in a binder resin. There are no particular limitations on the binder resin, but for example, a thermosetting resin or a thermoplastic resin can be used.

The magnetic permeability _μ3 in the thickness direction of the magnetic permeable layer is preferably 1.26×10 ^-6 to 3.78×10 ^-4 H/m, more preferably 3.78×10 ^-6 to 1.26×10 ^-4 H/m, and even more preferably 1.26×10 ^-5 to 6.30×10 ^-5 H/m. By having the magnetic permeability _μ3 within the above range, the accuracy of eddy current type endpoint detection tends to be further improved.

[Method of manufacturing polishing pad]
The polishing pad of this embodiment can be manufactured by known methods such as a method of bonding a polishing layer and a base layer together, or a method of forming a polishing layer on a base layer.

The method for forming the polishing layer is not particularly limited, but examples include the above-mentioned wet solidification method, the above-mentioned dry solidification method, and a method for hardening a curable resin. In this embodiment, when magnetic particles are contained in the polishing layer, the magnetic particles can be mixed into the resin solution before solidification, a liquid containing a prepolymer and a hardener, or the resin before hardening.

The method for forming the base layer is not particularly limited, but examples include methods for forming each of the above foams by known methods. In this embodiment, when magnetic particles are contained in the base layer, the magnetic particles can be mixed into the matrix resin of the foam at the stage of forming the foam.

[Method for manufacturing polished product]
The method for producing a polished product of this embodiment includes a polishing process in which the polishing pad is used to polish a workpiece to obtain a polished product, and an end point detection process in which an eddy current method is used to detect the end point during the polishing.

[Polishing process]
The polishing process may be a primary lapping process (rough lapping), a secondary lapping process (finish lapping), a primary polishing process (rough polishing), a secondary polishing process (finish polishing), or a process that combines these processes. Note that, here, "lapping" refers to polishing at a relatively high rate using coarse abrasive grains, and "polishing" refers to polishing at a relatively low rate using fine abrasive grains to improve the surface quality.

Among these, the polishing pad of this embodiment is preferably used for chemical mechanical polishing. Below, the method for manufacturing the polished product of this embodiment will be explained using chemical mechanical polishing as an example, but the method for manufacturing the polished product of this embodiment is not limited to the following.

The object to be polished is not particularly limited, but examples thereof include materials such as semiconductor devices and electronic components, particularly thin substrates (objects to be polished) such as Si substrates (silicon wafers), SiC (silicon carbide) substrates, GaAs (gallium arsenide) substrates, glass, and substrates for hard disks and LCDs (liquid crystal displays). In particular, semiconductor devices having metal wiring such as W (tungsten) and Cu (copper) are included.

The polishing method may be a conventionally known method, and is not particularly limited. For example, first, the object to be polished held on a holding platen arranged opposite the polishing pad is pressed against the polishing surface, and the polishing pad and/or holding platen are rotated while supplying slurry from the outside. The polishing pad and holding platen may rotate in the same direction at different rotation speeds, or in different directions. In addition, the object to be polished may be polished while moving (rotating) inside the frame during the polishing process.

The slurry may contain water, chemical components such as an oxidizing agent represented by hydrogen peroxide, additives, abrasive grains (abrasive particles; for example, SiC, SiO ₂ , Al ₂ O ₃ , CeO ₂ ), etc. depending on the object to be polished and the polishing conditions.

[End point detection process]
The manufacturing method of the polished workpiece of this embodiment has an end point detection process in which the end point is detected by an eddy current method in the above-mentioned polishing process. As the end point detection method by the eddy current method, specifically, a conventionally known method can be used. FIG. 2 shows a schematic diagram of the end point detection method by the eddy current method. This schematic diagram shows a chemical mechanical polishing process in which a wafer W held by a top ring 21 is pressed against a polishing pad 10 attached on a table 22 while flowing a slurry (not shown) to scrape off an uneven film on the surface of the wafer W and flatten it. The polishing device 20 is equipped with a film thickness detection sensor 23 on the table 22 to monitor the film thickness in order to end the process with a predetermined film thickness at the same time as the flattening. The film to be monitored includes a metal film and an insulating film, and an eddy current film thickness detection sensor 23 is equipped for detecting the metal film.

As shown in FIG. 3, magnetic field lines H1 are generated in a direction penetrating the table 22 from the film thickness detection sensor 23, which is provided at a position passing through the center of the wafer W on the table 22. If a conductive film W1 is present on the wafer W, eddy currents C are generated on the surface of the wafer W when the magnetic field lines pass through the conductive film W1. When the eddy currents flow, magnetic field lines H2 are generated in the opposite direction to the magnetic field lines from the film thickness detection sensor 23. The resistance of the eddy currents changes depending on the thickness of the metal film W1, so by measuring the strength of these magnetic field lines H2 in the opposite direction, the thickness of the metal film W1 during polishing can be identified and the end point can be detected.

Films that can be measured using the eddy current method are metal films such as Cu and W. Figure 3 shows an image of eddy current generation. As polishing of the wafer W progresses, the metal film W1 on the surface of the wafer W decreases. The output of the eddy current sensor 23 changes accordingly, measuring the amount of film thickness change, and it can be confirmed that the end point at which the metal film W1 is completely removed is detected.

The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited in any way by the following examples.

(Preparation of abrasive layer A)
A prepolymer containing an adduct of 2,4-tolylene diisocyanate and polyoxytetramethylene glycol was added with 3,3'-dichloro-4,4'-diaminodiphenylmethane as a curing agent, and cured to form a polishing layer A.

(Preparation of abrasive layer B)
Polythiophene as a conductive polymer material was added to the components of the abrasive layer A in an amount of 0.5% by weight based on the total amount of the resin, and the abrasive layer B was formed by hardening.

(Preparation of abrasive layer C)
Polythiophene was added as a conductive polymer material to the components of the polishing layer A in an amount of 5% by weight based on the total amount of resin, and the mixture was cured to form the polishing layer C.

(Preparation of substrate layer a)
A nonwoven fabric made of polyethylene fibers was impregnated with a polyurethane resin solution, and then wet-coagulated and dried to obtain a base layer a.

(Preparation of substrate layer b)
Substrate layer b was obtained in the same manner as substrate layer a, except that Ni-Zn-Cu ferrite powder having an average particle size of 30 μm was added as magnetic particles to the polyurethane resin solution of substrate layer a so as to account for 5% by weight of the total amount of the substrate layer.

(Preparation of substrate layer c)
Substrate layer c was obtained in the same manner as substrate layer a, except that Ni-Zn-Cu ferrite powder having an average particle diameter of 30 μm was added as magnetic particles to the polyurethane resin solution of substrate layer a so as to account for 10% by weight of the total amount of the substrate layer.

(Preparation of magnetic permeable layer)
Ni-Zn-Cu ferrite powder with an average particle size of 30 μm was dispersed in a polyester solution, which was then applied onto a PET film, and then dried and cured to obtain a magnetically permeable layer with a thickness of 100 μm.

(Measurement of magnetic permeability)
A magnetic permeability measuring tool (e.g., Agilent's 16454A) was connected to a network analyzer (e.g., Agilent's E5071C), and a doughnut-shaped sample punched to an outer diameter of 7 mm and an inner diameter of 3 mm was set on the tool, and the magnetic permeability was measured using a predetermined program. The magnetic permeability of each of the polishing layers A to C, the base layers a to c, and the magnetic permeable layer was as shown in Tables 1 to 3 below.

Examples and Comparative Examples
As shown in Table 4 below, the polishing pads of the examples and comparative examples were prepared by combining the polishing layer, the base layer, and the magnetic permeable layer. In addition, the conventionally known polishing pad IC1000 (manufactured by Nitta Haas Co., Ltd.) was used as the polishing pad of the comparative example. The magnetic permeability μ _all in the thickness direction of the polishing pad was measured for each example and comparative example. Note that, for Examples 1, 4, and 10 in which a magnetic permeable layer is provided, Table 4 shows the case where the magnetic permeable layer is provided between the polishing layer and the base layer, but the magnetic permeability was measured when the magnetic permeable layer is provided between the polishing layer and the base layer and when the magnetic permeable layer is provided under the base layer, but no significant difference was observed.

In all of Examples 1 to 10, the magnetic permeability μ _all was 2.52×10 ⁻⁶ or more, and eddy current end point detection could be performed with good accuracy.

The polishing pad of the present invention has industrial applicability as a pad suitable for polishing devices in which a conductive layer or the like is formed on a semiconductor wafer.

10: Polishing pad, 11: Polishing layer, 11a: Polishing surface, 12: Base layer, 20: Polishing device, 21: Top ring, 22: Table, 23: Film thickness detection sensor, W: Wafer, W1: Metal film, H1, H2: Magnetic field lines, C: Eddy current

Claims (4)

A polishing pad having a polishing layer and a base layer laminated on the polishing layer,
The magnetic permeability μ _all of the polishing pad in the thickness direction is 2.52×10 ⁻⁶ to 1.26×10 ⁻⁴ H/m;
The base layer includes a soft magnetic material.
Polishing pad for eddy current endpoint detection. The magnetic permeability μ ₁ in the thickness direction of the polishing layer is 1.26×10 ⁻⁶ to 1.26×10 ⁻⁵ H/m.
The polishing pad of claim 1. The magnetic permeability μ ₂ in the thickness direction of the base layer is 1.26×10 ⁻⁶ to 3.78×10 ⁻⁴ H/m.
The polishing pad according to claim 1 or 2. The method includes a polishing step of polishing a workpiece by using the polishing pad according to any one of claims 1 to 3 to obtain a polished workpiece, and an end point detection step of detecting an end point during the polishing by an eddy current method.
A method for manufacturing polished workpieces.