JP2021053765A - Polishing pad - Google Patents

Abstract

To prevent a window for endpoint detection from falling off from a polishing layer when polishing an object to be polished.SOLUTION: A polishing pad 3 includes a polishing layer 3C whose top face is a polishing surface 3A, and a transparent window 3B for endpoint detection is positioned at a prescribed position in the polishing layer 3C. The window 3B for endpoint detection transmits inspection light L1, and further transmits reflectance from an object 2 to be polished. During polishing, an endpoint of polishing can be detected on the basis of changes in intensity of the reflectance from the object to be polished. On an outer peripheral part of the window 3B for endpoint detection, a plurality of bulged parts 3Ba are formed, whereas on an inner peripheral surface of an open hole 3Ca of the polishing layer 3C, recesses 3Cb engaging with the bulged parts 3Ba are formed. Since the plurality of bulged parts 3Ba are engaged with the recesses 3Cb, the window 3B for endpoint detection is prevented from falling off from the open hole 3Ca of the polishing layer 3C during polishing of the object 2 to be polished.SELECTED DRAWING: Figure 3

Description

The present invention relates to a polishing pad, and more particularly to a polishing pad provided with a window for detecting an end point for detecting the end point of processing at the time of processing an object to be polished.

Conventionally, a polishing pad for polishing a wafer as an object to be polished has been known, and further, in order to detect the end point when polishing the wafer, a transparent end point detection window for transmitting inspection light is provided. Polishing pads are known (for example, Patent Documents 1 to 3).
In such a conventional polishing pad, a through hole is provided in the polishing layer as the main body, and a transparent window member serving as an end point detection window is provided therein in order to prevent leakage of the polishing liquid (slurry) used for polishing. It is configured to be attached. Specifically, in the polishing pad of Patent Document 1, a window member serving as an end point detection window is fitted into a through hole of a polishing layer and adhered with a photocurable adhesive. In the polishing pad, a window member serving as an end point detection window is fitted into a through hole of the polishing layer without an adhesive. Further, in the polishing pad of Patent Document 3, a single recess is formed on the inner peripheral surface of the through hole of the polishing layer, while a convex that engages with the recess on the outer peripheral surface of the window member serving as the end point detection window. Forming a part.

Japanese Unexamined Patent Publication No. 2004-343090 Japanese Unexamined Patent Publication No. 2004-134039 Japanese Unexamined Patent Publication No. 2006-110686

By the way, each of the above-mentioned conventional polishing pads has the following problems.
That is, in the polishing pad of Patent Document 1, since the photocurable adhesive comes into contact with the surface to be polished of the wafer during polishing of the wafer, scratches or the like occur on the surface to be polished of the wafer and the polishing performance is deteriorated. There was a problem. Further, in the polishing pad of Patent Document 2, the fitting of the end point detection window (window member) to the through hole of the polishing layer tends to be insufficient, and the end point detection is performed from the through hole of the polishing layer during wafer polishing. There was a risk that the window would fall off.
Further, in the polishing pad of Patent Document 3, the polishing layer of the polishing pad and the end point detection window are worn away with the use of the polishing pad, so that the convex portion formed on the outer peripheral surface of the end point detection window disappears. Then, there is a possibility that the end point detection window may easily fall out of the through hole during the subsequent polishing of the wafer.
Therefore, an object of the present invention is to provide a polishing pad capable of preventing deterioration of polishing performance and preventing the end point detection window from falling off from the polishing layer.

In view of the above circumstances, the present invention is provided in a polishing layer having a polishing surface for polishing an object to be polished and an end point detection provided in a through hole of the polishing layer to transmit inspection light and reflected light from the object to be polished. In a polishing pad with a window
A plurality of convex portions are formed on the side portion of the end point detection window in a direction orthogonal to the polished surface.
A plurality of concave portions that engage with the convex portion of the end point detection window are formed on the inner peripheral surface of the through hole of the polishing layer.
It is characterized in that the convex portions and the concave portions at the plurality of locations are engaged with each other.

According to such a configuration, the end point detection window is attached to the through hole in a state where the irregularities at a plurality of locations are engaged with each other without using an adhesive. Therefore, during the polishing process of the object to be polished, the surface to be processed is not adversely affected by the adhesive, and the plurality of concave portions and the convex portions are engaged with each other. It is possible to prevent the detection window from falling out of the through hole of the polishing layer.

The schematic perspective view which shows one Example of this invention. Sectional drawing of the main part along the line II-II of FIG. Enlarged view of the main part of FIG. The figure which shows the manufacturing process of the polishing layer of the polishing pad shown in FIG. 2 is a cross-sectional view of a main part, FIG. 5A shows a state before use of the polishing pad, and FIG. 5B shows a state after use. FIG. 6A is a cross-sectional view showing another embodiment of the present invention, FIG. 6A shows a state before use of the polishing pad, and FIG. 6B shows a state after use. FIG. 7A is a cross-sectional view showing another embodiment of the present invention, FIG. 7A shows a state before use of the polishing pad, and FIG. 7B shows a state after use.

Hereinafter, the present invention will be described with respect to the illustrated examples. In FIGS. 1 to 2, 1 is a polishing device, and the polishing device 1 polishes a thin plate-shaped object 2 (for example, a semiconductor wafer) with a polishing pad 3. It is designed to do. Further, this polishing device 1 irradiates the surface to be polished 2A of the object to be polished 2 with the inspection light L1 when performing the polishing process for polishing the object to be polished 2, and detects the reflected light by the detection mechanism 7 (light receiving unit 7B). By receiving light with, it is possible to detect the progress of the polishing process and the end point at the end of the process.
The polishing apparatus 1 includes a polishing surface plate 4 located on the lower side and having a polishing pad 3 fixed on the upper surface, a holding surface plate 5 located on the upper side and holding an object to be polished 2 on the lower surface, and an object to be polished. A slurry supply mechanism 6 for supplying a slurry between the polishing pad 3 and the polishing pad 3 and a detection mechanism 7 for detecting the progress of polishing of the object 2 to be polished and the end point of the processing by using the inspection light L1 are provided.
The object 2 to be polished by the polishing apparatus 1 is an optical material, a silicon wafer, a glass substrate for a liquid crystal, a semiconductor substrate, or a plate-like object such as glass, metal, or ceramic. Further, as the slurry supplied by the slurry supply mechanism 6, a conventionally known suitable slurry can be used depending on the target object 2 to be polished and the required processing accuracy.
The polishing surface plate 4 and the holding surface plate 5 each have a substantially disk shape, and each of them is rotated in the direction of an arrow by a drive mechanism (not shown), and the holding surface plate 5 is provided so as to be able to move up and down. ing.
When polishing the object to be polished 2, the holding platen 5 presses the surface (lower surface) 2A of the object 2 to be polished against the polishing surface 3A of the polishing pad 3 at a set pressure, and they are pressed against each other at a set pressure. While being relatively rotated, the slurry is supplied from the slurry supply mechanism 6 between the surface to be polished 2A of the object to be polished 2 and the surface 3A to be polished of the polishing pad 3.

By the way, when polishing the object to be polished 2, it is necessary to detect the progress of the polishing process of the object to be polished 2 and the end point at which the process ends. Therefore, this polishing device 1 irradiates the inspection light L1 from the lower side to the upper side, and detects the progress status of the polishing process and the processing end point based on the reflected light from the surface 2A to be polished of the object to be polished 2. The detection mechanism 7 is provided. Further, a transparent end point detection window 3B is provided at a predetermined position of the polishing pad 3 to transmit the inspection light L1 and the reflected light from the surface to be polished 2A of the object to be polished 2.
The polishing pad 3 includes a disk-shaped polishing layer 3C located on the upper side and a disk-shaped support layer 3D bonded to the lower surface of the polishing layer 3C with an adhesive. A transparent end point detection window 3B is provided at a predetermined position of the polishing layer 3C, and the position of the support layer 3D on the lower side thereof is for passing the inspection light L1 and the reflected light from the object to be polished 2. A through hole 3Da is bored.
The upper surface 3Bb of the end point detection window 3B and the polishing surface 3A which is the upper surface of the polishing layer 3C are flush with each other. Further, the lower surface 3Bc of the end point detection window 3B and the lower surface of the polishing layer 3C are flush with each other, and the upper surface of the support layer 3D is adhered to the lower surface of the polishing layer 3C with an adhesive. The lower surface (lower surface of the support layer 3D) of the polishing pad 3 composed of the upper and lower polishing layers 3C and the support layer 3D is fixed to the upper surface 4A of the polishing surface plate 4 with double-sided tape or an adhesive. There is.

The polishing layer 3C is made of hard urethane. The rigid urethane is a polyurethane obtained by using a urethane prepolymer which is a reaction intermediate between a polyol component and an isocyanate component, and adding and mixing a curing agent (chain extender) such as diamines or diols, a foaming agent, a catalyst and the like. Manufactured by a prepolymer method that cures a polyurea resin. Although the polishing layer and the end point detection window will be described below as the polyurethane polyurea resin, a polyurethane resin or a polyurea resin may be used.

As a method for producing the polishing layer 3C, for example, a preparatory step of preparing at least a polyurethane bond-containing isocyanate compound as a prepolymer, a curing agent, and a hollow body; at least the above-mentioned polyurethane bond-containing isocyanate compound and a curing agent are mixed and molded. A mixing step of obtaining a mixed solution for molding; a molded body molding step of molding a polyurethane polyurea resin molded body from the molded body molding mixed solution; and forming a polishing layer having the polished surface from the polyurethane polyurea resin molded body. It may include a polishing layer forming step.

As the preparatory step, for the production of the polishing layer 3C, for example, a polyurethane bond-containing isocyanate compound, a curing agent, and a hollow body are used as raw materials for the polyurethane polyurea resin molded product. Further, a polyol compound may be used together with the above components, and components other than the above may be used in combination as long as the effects of the present invention are not impaired.

The polyurethane bond-containing isocyanate compound prepared in the preparation step is a compound obtained by reacting the following polyisocyanate compound and a polyol compound under commonly used conditions, and contains a polyurethane bond and an isocyanate group in the molecule. It is a compound. Further, other components may be contained in the polyurethane bond-containing isocyanate compound as long as the effects of the present invention are not impaired.
As the polyurethane bond-containing isocyanate compound, a commercially available compound may be used, or a compound synthesized by reacting a polyisocyanate compound with a polyol compound may be used. The above reaction is not particularly limited, and the addition polymerization reaction may be carried out using a method and conditions known in the production of polyurethane resin.
For example, a polyisocyanate compound heated to 50 ° C. while stirring in a nitrogen atmosphere is added to a polyol compound heated to 40 ° C., and after 30 minutes, the temperature is raised to 80 ° C. and further reacted at 80 ° C. for 60 minutes. It can be manufactured by such a method.

First, the polyisocyanate compound means a compound having two or more isocyanate groups in the molecule. The polyisocyanate compound is not particularly limited as long as it has two or more isocyanate groups in the molecule.
For example, examples of the diisocyanate compound having two isocyanate groups in the molecule include m-phenylenediocyanate, p-phenylenediocyanate, 2,6-tolylene diisocyanate (2,6-TDI), and 2,4-tolylene diisocyanate (2). , 4-TDI), naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), 4,4'-methylene-bis (cyclohexylisocyanate) (hydrogenated MDI), 3,3'-dimethoxy -4,4'-biphenyldiisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4'-diphenylpropanediisocyanate, trimethylenediisocyanate, hexamethylenediisocyanate, propylene -1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylenediisothiocianate, xylylene-1,4-diisocyanate, Ethilidine diisocyanate and the like can be mentioned.
Further, as the polyisocyanate compound, a diisocyanate compound is preferable, among them, 2,4-TDI, 2,6-TDI and MDI are more preferable, and 2,4-TDI and 2,6-TDI are particularly preferable.
These polyisocyanate compounds may be used alone or in combination of a plurality of polyisocyanate compounds.

Next, the polyol compound means a compound having two or more alcoholic hydroxyl groups (OH) in the molecule.
Examples of the polyol compound used for synthesizing the polyurethane bond-containing isocyanate compound include diol compounds such as ethylene glycol, diethylene glycol (DEG) and butylene glycol, triol compounds and the like; poly (oxytetramethylene) glycol (or polytetramethylene ether glycol). Polyether polyol compounds such as (PTMG); polyester polyol compounds such as a reaction product of ethylene glycol and adipic acid and a reaction product of butylene glycol and adipic acid; polycarbonate polyol compound, polycaprolactone polyol compound and the like can be mentioned.
Further, trifunctional propylene glycol to which ethylene oxide is added can also be used. Among these, PTMG or a combination of PTMG and DEG is preferable.
The above polyol compound may be used alone, or a plurality of polyol compounds may be used in combination.

Here, the NCO equivalent of the prepolymer, which indicates the molecular weight of the prepolymer per NCO group, is preferably 200 to 800, more preferably 300 to 700, and further preferably 400 to 600. More preferred.
Specifically, the NCO equivalent of the prepolymer can be determined as follows.
NCO equivalent of prepolymer = (mass part of polyisocyanate compound + mass part of polyol compound) / [(number of functional groups per molecule of polyisocyanate compound x mass part of polyisocyanate compound / molecular weight of polyisocyanate compound)-(polyisocyanate compound) Number of functional groups per molecule x mass part of polyol compound / molecular weight of polyol compound)]

As the curing agent, for example, a polyamine compound and / or a polyol compound can be used.
The polyamine compound means a compound having two or more amino groups in the molecule, and an aliphatic or aromatic polyamine compound, particularly a diamine compound, can be used.
For example, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (hereinafter, MOCA). ), Polyamine compounds having the same structure as MOCA, and the like can be mentioned.
Further, the polyamine compound may have a hydroxyl group, and examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, and di-2-hydroxy. Examples thereof include ethyl propylenediamine, 2-hydroxypropyl ethylenediamine, di-2-hydroxypropyl ethylenediamine and the like.
As the polyamine compound, a diamine compound is preferable, MOCA, diaminodiphenylmethane, and diaminodiphenylsulfone are more preferable, and MOCA is particularly preferable.
The polyamine compound may be used alone or in combination of a plurality of polyamine compounds.
The polyamine compound is preferably defoamed under reduced pressure in a heated state, if necessary, in order to facilitate mixing with other components and / or to improve the uniformity of the bubble diameter in the subsequent molding step. As a defoaming method under reduced pressure, a method known in the production of polyurethane may be used, and for example, defoaming can be performed at a vacuum degree of 0.1 MPa or less using a vacuum pump.
When a solid compound is used as the curing agent, it can be defoamed under reduced pressure while being melted by heating.

Further, as the polyol compound as a curing agent, any compound such as a diol compound and a triol compound can be used without particular limitation. It may also be the same as or different from the polyol compound used to form the prepolymer.
Specific examples include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3 Examples thereof include low molecular weight diols such as -methyl-1,5-pentanediol and 1,6-hexanediol, and high molecular weight polyol compounds such as poly (oxytetramethylene) glycol, polyethylene glycol and polypropylene glycol.
The above polyol compound may be used alone, or a plurality of polyol compounds may be used in combination.

Here, the R value, which is the equivalent ratio of the active hydrogen groups (amino groups and hydroxyl groups) present in the curing agent to the isocyanate groups present at the ends of the polyurethane bond-containing isocyanate compound, is 0.60 to 1.40. So, mix each component. The R value is preferably 0.65 to 1.30, more preferably 0.70 to 1.20.

The hollow body means a microsphere having a void. Microspheres include spherical, elliptical, and similar shapes. Examples of the hollow body are an unexpanded heat-expandable microsphere composed of an outer shell (polymer shell) made of a thermoplastic resin and a low boiling point hydrocarbon contained in the outer shell, and an unexpanded heat-expandable microsphere. Examples thereof include those obtained by heating and expanding a spherical body.
Examples of the polymer shell include acrylonitrile-vinylidene chloride copolymer, acrylonitrile-methylmethacrylate copolymer, vinyl chloride-ethylene copolymer and the like, as disclosed in Japanese Patent Application Laid-Open No. 57-137323. A thermoplastic resin can be used. Similarly, as the low boiling point hydrocarbon contained in the polymer shell, for example, isobutane, pentane, isopentane, petroleum ether and the like can be used.
In addition to using the above hollow body, bubbles may be formed by using chemical foaming such as water foaming or foaming by mechanical stirring, or these methods may be combined.

Next, the mixing step will be described. In the mixing step, the polyurethane bond-containing isocyanate compound as a prepolymer, the curing agent and the hollow body prepared in the above preparation step are supplied into the mixer and stirred / mixed. The mixing step is performed in a state of being heated to a temperature at which the fluidity of each of the above components can be ensured.
The mixing order is not particularly limited, but a mixed solution in which a polyurethane bond-containing isocyanate compound and a hollow body are mixed and a mixed solution in which a curing agent and other components are mixed if necessary are prepared, and both mixed solutions are mixed. It is preferable to supply the mixture into the vessel and mix and stir. In this way, a mixed solution for molding a molded product is prepared.

Next, in the molded body molding step, the mixed solution for molding body molding prepared in the above mixing step is poured into a mold at 50 to 100 ° C., and the prepolymer and the curing agent react to form a polyurethane polyurea resin. The mixed solution is cured by the above method to form a polyurethane polyurea resin molded product.

Then, in the polishing layer forming step, the polyurethane polyurea resin molded body obtained by the molded body molding step is sliced into a sheet, and the sliced resin sheet is cut into a predetermined shape.
The front surface and / or the back surface of the resin sheet obtained in this manner is ground. One surface becomes the polished surface, and by performing cutting or the like on the polished surface using a required cutter, grooves having an arbitrary pitch, width, and depth can be formed, thereby polishing. Layer 3C will be obtained.

For the support layer 3D, an impregnated non-woven fabric impregnated with a resin, a foam such as polyethylene foam or polyurethane foam, or a support base material such as polyethylene terephthalate (PET) can be used.
When the impregnated non-woven fabric is used as the support layer 3D, in order to produce the support layer 3D, at least a step of wet-solidifying the resin impregnated in the non-woven fabric substrate and a step of buffing both sides of the wet-solidified fiber aggregate are performed. Including. The non-woven fabric substrate of this example is not particularly limited, and those known by species can be adopted.
Examples of the non-woven fabric substrate include non-woven fabrics such as polyolefine-based, polyamide-based, and polyester-based. Further, the method of entwining the fibers when obtaining the non-woven fabric substrate is not particularly limited, and may be, for example, needle punching or water flow entanglement.
As the non-woven fabric substrate, one of the above-mentioned types can be used alone, and two or more types can be used in combination. The non-woven fabric substrate has many gaps between fibers and is rich in water absorption, but the gaps are filled with the resin by impregnating with the resin, so that the water absorption is lowered.

The resin to be impregnated in the non-woven substrate is polyurethane such as polyurethane and polyurethane polyurea, acrylic such as polyacrylate and polyacrylonitrile, vinyl such as polyvinyl chloride, polyvinyl acetate and polyvinylidene fluoride, polysulfone and polyethersulfone. Examples thereof include polysulfone-based, acetylated cellulose, acylated cellulose-based such as butyrylized cellulose, polyamide-based and polystyrene-based.

The density of the non-woven fabric is preferably 0.3 g / cm3 or less, more preferably 0.1 to 0.2 g / cm3 in the state before resin impregnation (web state). The density of the non-woven fabric after impregnation with the resin is preferably 0.5 g / cm3 or less, and more preferably 0.3 to 0.4 g / cm3. If the density of the non-woven fabric is too high, the processing accuracy tends to deteriorate, and if it is too low, water absorption tends to be relatively easy.
The adhesion rate of the resin to the non-woven fabric is represented by the weight of the attached resin with respect to the weight of the non-woven fabric, and is preferably 50% or more, more preferably 75 to 200%. If the adhesion rate of the resin is too large, it tends not to exhibit the desired cushioning property as the support layer 3D, and if it is too low, the support layer 3D absorbs water and affects the polishing characteristics.

A case where a polyurethane resin is used as an example of impregnating a non-woven fabric substrate with a resin and performing a wet solidification will be described. The polyurethane resin, a solvent that can dissolve the polyurethane resin and is mixed with the coagulation liquid described later, and other additives as necessary are mixed, and if necessary, defoamed under reduced pressure to obtain the polyurethane resin. Prepare the solution. The solvent is not particularly limited, and examples thereof include N, N-dimethylformamide (DMF), isopropyl alcohol (IPA), and N, N-dimethylacetamide. For example, the polyurethane resin may be dissolved in a solvent in the range of 5 to 25% by mass, more preferably 8 to 15% by mass, based on the total amount of the polyurethane resin solution. In the case of the above range, it is possible to easily spread the non-woven fabric substrate throughout.

Next, after immersing the sheet-shaped non-woven fabric in the polyurethane resin solution, the resin solution is squeezed out using a mangle roller capable of pressurizing between the pair of rollers to adjust the amount of the resin solution to adhere to the non-woven fabric substrate. Is impregnated with the resin solution substantially uniformly. Next, the polyurethane resin is coagulated and regenerated by immersing the non-woven fabric substrate impregnated with the resin solution in a coagulating liquid containing a poor solvent for the resin, for example, water as a main component. An organic solvent such as a polar solvent other than the solvent in the resin solution may be added to the coagulating liquid in order to adjust the regeneration rate of the resin. The temperature of the coagulating liquid is not particularly limited as long as it can coagulate the resin, and may be, for example, 15 to 60 ° C. Then, if necessary, the solvent remaining in the non-woven fabric impregnated with the resin may be removed by using a conventionally known cleaning liquid, and further, the cleaning liquid may be removed by using a mangle roller or drying. .. In this way, a fiber aggregate in which the resin is wet-coagulated can be obtained. After that, both sides of the fiber aggregate are buffed to adjust the thickness of the fiber aggregate.

In the fiber aggregate whose thickness has been adjusted, through holes are formed at predetermined positions in the thickness direction. The through hole can be formed by drilling or the like. As a result, the support layer 3D can be obtained.

For the support layer 3D, for example, a transparent base material of polyethylene terephthalate (PET) can also be used. It can be adhered and fixed to the polishing layer 3C by applying pressure as necessary using double-sided tape or an adhesive on both sides of the polyethylene terephthalate base material. The double-sided tape and adhesive used for adhesion to the polishing layer 3C are not particularly limited, and can be arbitrarily selected from the double-sided tapes and adhesives known in the art. When the base material is transparent, the inspection light is transmitted, so that it is not necessary to provide a through hole.

The end point detection window 3B can use the same material as the polishing layer, and is formed of, for example, hard urethane. The hard urethane of the end point detection window 3B uses a urethane prepolymer, and a pre-curing polyurethane polyurea resin obtained by adding and mixing a curing agent (chain extender) such as diamines or diols, an additive, a catalyst, etc. Manufactured by the polymer method.

As the urethane prepolymer used for the end point detection window, for example, a polyurethane bond-containing isocyanate compound similar to the polishing layer can be used. As the polyurethane bond-containing isocyanate compound, a commercially available compound may be used, or a compound synthesized by reacting a polyisocyanate compound with a polyol compound may be used. The above reaction is not particularly limited, and the addition polymerization reaction may be carried out using a method and conditions known in the production of polyurethane resin. Further, other components may be contained in the polyurethane bond-containing isocyanate compound as long as the effects of the present invention are not impaired.
As the polyisocyanate compound, a diisocyanate compound is preferable, and a diisocyanate compound used in the polishing layer can be used. Among the diisocyanate compounds, 2,4-TDI, 2,6-TDI and MDI are more preferable, and 2,4-TDI and 2,6-TDI are particularly preferable. These polyisocyanate compounds may be used alone or in combination of a plurality of polyisocyanate compounds.

As the polyol compound used for the synthesis of the polyurethane bond-containing isocyanate compound, the polyol compound used in the polishing layer can also be used. Among the polyol compounds, PTMG or a combination of PTMG and DEG is preferable. The above polyol compound may be used alone, or a plurality of polyol compounds may be used in combination.

Regarding the prepolymer used for the end point detection window, the NCO equivalent of the prepolymer indicating the molecular weight of the prepolymer per NCO group is preferably 200 to 800, more preferably 300 to 700, and 400. It is even more preferably ~ 600.

As the curing agent, for example, a polyamine compound and / or a polyol compound similar to the compound used in the polishing layer can be used. As the polyamine compound, a diamine compound is preferable, MOCA, diaminodiphenylmethane, and diaminodiphenylsulfone are more preferable, and MOCA is particularly preferable. The polyamine compound may be used alone or in combination of a plurality of polyamine compounds.
The polyamine compound used for the end point detection window may be defoamed under reduced pressure in a heated state as necessary to facilitate mixing with other components and / or to remove air bubbles, as in the case of the polishing layer. preferable.

Further, as the polyol compound as a curing agent used for the end point detection window, any compound such as a diol compound or a triol compound can be used without particular limitation. Further, it may be the same as or different from the polyol compound used for forming the prepolymer used for the end point detection window. The above polyol compound may be used alone, or a plurality of polyol compounds may be used in combination.

Here, the R value which is the equivalent ratio of the active hydrogen groups (amino groups and hydroxyl groups) present in the curing agent used in the end point detection window to the isocyanate group existing at the end of the polyurethane bond-containing isocyanate compound used in the end point detection window. , Each component is mixed so as to be 0.60 to 1.40. The R value is preferably 0.65 to 1.30, more preferably 0.70 to 1.20.

Known antioxidants, ultraviolet absorbers, and light stabilizers can be used as additives for the end point detection window. By using these additives, it is possible to suppress yellowing and deterioration of the end point detection window.

On the polishing surface plate 4, reflection from the light emitting portion 7A and the object to be polished 2 that irradiate the inspection light L1 vertically upward at the position below the through hole 3Da of the end point detection window 3B and the support layer 3D of the polishing pad 3. A light receiving unit 7B that receives light is provided. The inspection mechanism 7 includes a light emitting unit 7A, a light receiving unit 7B, and a control unit 7C that controls their operations and detects the progress of processing and the end point at which processing ends during polishing.
During the polishing process of the object to be polished 2, the inspection light L1 is emitted upward from the light emitting portion 7A of the inspection mechanism 7, so that the inspection light L1 passes through the transparent end point detection window 3B and is to be polished. The surface to be polished 2A of the object 2 is irradiated. Then, the inspection light L1 is reflected downward by the surface to be polished 2A of the object to be polished 2, and the reflected light is transmitted through the transparent end point detection window 3 and detected by the light receiving unit 7B. The reflected light detected by the light receiving unit 7B is transmitted to the control unit 7C.
Then, as the polishing process of the object to be polished progresses and the surface 2A to be polished of the object to be polished 2 is gradually polished, the intensity of the reflected light detected by the light receiving portion 7B and the like change. When the intensity of the reflected light detected by the light receiving unit 7B becomes the intensity registered in advance, the control unit 7C determines that the surface to be polished 2A has reached the processing end point, and stops the polishing process. It has become. Then, since the drive mechanism is stopped, the rotation of the polishing surface plate 4 and the holding surface plate 5 is stopped, and the supply of the slurry from the slurry supply mechanism 6 is also stopped.
The detection mechanism 7 detects the end point of the polishing process when the object 2 to be polished is polished in this way. The configuration of the detection mechanism 7 using such an inspection light L1 is known from Patent Documents 1 to 3 described above.

Therefore, this embodiment is characterized in that the end point detection window 3B provided on the polishing layer 3C and its mounting location are improved as follows, whereby the end point detection window 3B is processed from the polishing layer 3C. It prevents it from falling out.
As shown in FIG. 3, a through hole 3Ca in the vertical direction is formed at a predetermined position of the polishing layer 3C, and a substantially columnar end point detection window 3B is provided in a state of being engaged without a gap. ..
The end point detection window 3B is formed in a short columnar shape having substantially the same axial dimension and outer diameter. Flange-shaped bulging portions 3Ba are formed at two locations on the outer peripheral portion which is the side surface of the end point detection window 3B while maintaining a predetermined interval in the axial direction. That is, in the direction orthogonal to the polished surface 3A, bulging portions 3Ba as convex portions are formed at two locations on the outer peripheral portion of the end point detection window 3B. The end point detection window 3B is manufactured by curing a mixture of urethane prepolymer and a curing agent, and is capable of transmitting light. Although it has been explained that the end point detection window 3B is columnar, it may be a prism such as a square column.
The thickness (axial dimension) and the outward bulging length of each bulging portion 3Ba are the same. The length (height) of the bulging portion is preferably 0.1 to 0.5 mm. By setting the length of the bulging portion to 0.1 to 0.5 mm, it is possible to secure the strength of the bulging portion and obtain the effect of preventing the end point detection window from falling off. Further, the distance (pitch) between the upper and lower bulging portions 3Ba is substantially the same as their thickness. The pitch of the bulging portion 3Ba is preferably 0.2 to 0.5 mm. By setting the pitch of the bulging portion 3Ba to 0.2 to 0.5 mm, the resin solution used as the material of the polishing layer 3C can be easily distributed, and a plurality of bulging portions can be easily formed (processed), and the bulging portion can be easily formed (processed). Strength can be ensured.
Further, the bulging portion 3Ba on the upper side is located on the lower side from the same upper surface 3Bb as the polished surface 3A by a dimension shorter than the thickness of the bulging portion 3Ba, and the bulging portion 3Ba on the lower side is located below the lower surface 3Bc. Is located on the upper side by about half the thickness of the bulging portion 3Ba. When the bulging portion 3Ba described later as another embodiment of the present invention forms a screw thread (spiral), the bulging portion 3B is continuously located from the upper surface 3Bb to the lower surface 3Bc.
On the other hand, the through hole 3Ca of the polishing layer 3C is formed so as to be engaged without a gap with the original outer peripheral surface 3Bd and the bulging portion 3Ba of the end point detection window 3B.
That is, the original outer peripheral surface 3Bd of the end point detection window 3B is fitted to the original inner peripheral surface of the through hole 3Ca without a gap. Further, two recesses 3Cb are formed at predetermined positions on the inner peripheral surface of the through hole 3Ca according to the shape and dimensions of each bulging portion 3Ba of the end point detection window 3B. Then, each bulging portion 3Ba of the end point detection window 3B is engaged with the recess 3Cb of the corresponding through hole 3Ca without a gap.
As described above, the end point detection window 3B of the present embodiment is formed with two bulging portions 3Ba for preventing falling off on the outer peripheral portion thereof, while the bulging portion 3Ca of the polishing layer 3C is formed with the bulging portion 3Ca. Two recesses 3Cb are formed in which the portions 3Ba are engaged without gaps.
The upper surface 3Bd of the end point detection window 3B is flush with the polishing surface 3A of the polishing layer 3C, and the lower surface 3Bc of the end point detection window 3 is flush with the lower surface 3Cc of the polishing layer 3C.
The upper surface of the polishing layer 3C is a polishing surface 3A that slides on the surface to be polished 2A of the object to be polished 2, and a groove 3Cd is formed at a predetermined position of the polishing surface 3A. The grooves 3Cd are formed on the polished surface 3A in a grid pattern, a concentric pattern, a radial pattern, or the like. The depths of the grooves 3Cd are all the same. Further, the depth of these grooves 3Cd is set to be deeper than the upper bulging portion 3Ba of the end point detection window 3B and shallower than the lower bulging portion 3Ba. The groove 3Cd is designed to hold or discharge the slurry. The polishing layer 3C and the end point detection window 3B in the polishing pad 3 of this embodiment are configured as described above.

Next, one aspect of the method for manufacturing the polishing layer 3C of the polishing pad 3 configured as described above will be described with reference to FIG.
That is, first, a columnar material 100 having a required outer diameter and axial length is manufactured. In the embodiment of this embodiment, a columnar columnar material is described, but a columnar columnar material may be used. The columnar material 100 becomes a window member that later becomes the end point detection window 3B. In this embodiment, a urethane prepolymer and a curing agent are prepared as materials for the columnar material, and after mixing them, they are poured into a window mold and cured to produce the columnar material 100 (FIG. 4). (A).
Next, a plurality of bulging portions 100A having a flange shape at equal pitches in the axial direction are formed on the outer peripheral portion of the columnar material 100. In this embodiment, by cutting the outer peripheral portion of the columnar material 100, bulging portions 100A having a predetermined width (vertical dimension) and depth (radial dimension) are formed at a plurality of axial directions. (See FIG. 4 (b)). In other words, in this step, the bulging portions 100A as a plurality of convex portions are formed on the outer peripheral portion of the columnar material 100.
Next, a rectangular box-shaped formwork 101 (not shown) is prepared, and the columnar material 100 on which the plurality of bulging portions 100A are formed is installed at a predetermined position in the formwork 101 so as to be in the vertical direction. To do.
After that, a mixed solution of a urethane prepolymer used as a material for the polishing layer 3C and a curing agent is poured into the mold 101 to harden it. As a result, the polyurethane polyurea resin molded body 102 having the same shape as the internal space of the mold 101 is produced in a state where the columnar material 100 is embedded (see FIG. 4C). The polyurethane polyurea resin molded body 102 serves as a portion of the polishing layer 3C.
Since the mixed solution of the urethane prepolymer used as the material of the polishing layer 3C and the curing agent is initially liquid, the outer peripheral surface of the columnar material 100 installed in the mold 101 and the plurality of bulging portions 100A The mixed solution is filled to the surface without gaps and hardens.
Next, after removing the polyurethane polyurea resin molded body 102 from the mold 101, the portion of the polyurethane polyurea resin molded body 102 in which the columnar material 100 is embedded is thinly cut along a horizontal plane to a predetermined thickness. It is cut out as a plurality of sheet-shaped members 103 (see FIG. 4D).
Then, the upper surface and the lower surface of the sheet-shaped member 103 are polished so as to be smooth. After that, a double-sided tape or the like is attached to the lower surface of the polishing layer 3C on the surface opposite to the polishing surface 3A. A groove for discharging and holding the slurry is formed at a required position on the upper surface to be the polished surface 3A. As a result, the polishing layer 3C of the polishing pad 3 of the present embodiment shown in FIG. 3 is completed (see FIG. 4D).
In this way, the polishing layer 3C of the polishing pad 3 is produced, and the portion of the columnar material 100 in the polishing layer 3C becomes the end point detection window 3B. At least two bulging portions 3Ba are maintained in the vertical direction (axial direction) on the outer peripheral portion of the end point detection window 3B, and they engage with the through holes 3Ca on the polishing layer 3C side at adjacent positions without gaps. It is in a state of being.
After the polishing layer 3C is produced in this way, the support layer 3D having the through hole 3Da formed in advance is attached to the lower surface of the polishing layer 3C. As a result, the production of the polishing pad 3 of this embodiment is completed (FIG. 4 (e)).
The lower surface (lower surface of the support layer 3D) of the polishing pad 3 manufactured in this manner is fixed to the upper surface of the polishing surface plate 4 with double-sided tape, an adhesive, or the like.
As a method of forming the bulging portion, an example of cutting the outer peripheral portion of the columnar material has been described, but the present invention is not limited to this. As another example, the mixed columnar material is poured into the window formwork in which the recess corresponding to the bulge of the end point detection window is formed, and when the columnar material is cured, the window formwork is used. There is a method of removing and taking out the cured columnar material. As yet another example, a polyurethane polyurea resin molded body is produced without embedding a columnar material, a through hole is formed at a predetermined position of the polyurethane polyurea resin molded body, and a through hole is provided by thread cutting or the like. To form. After that, a bulging portion can be formed in the columnar material by pouring a mixed solution of a urethane prepolymer and a curing agent into a through hole provided with a recess and curing the mixture.

In this embodiment, the polishing layer 3C of the polishing pad 3 is manufactured as described above, and the support layer 3D is adhered to the polishing layer 3D with double-sided tape, an adhesive, or the like to manufacture the polishing pad 3.
The polishing layer 3C of the polishing pad 3 of this embodiment is attached in a state where the end point detection window 3B is engaged with the through hole 3Ca of the polishing layer 3C without any gap without using an adhesive. Therefore, during the polishing process in which the polishing surface 3A of the polishing layer 3C slides on the polishing surface 2A of the object to be polished 2, the adhesive does not mix with the polishing surface 2A, and the adhesive adheres to the object 2 to be polished. It is possible to prevent adverse effects (scratches, etc.).
Further, in this embodiment, at least two bulging portions 3Ba in the end point detection window 3B are engaged with the recess 3Cb of the through hole 3Ca of the polishing layer 3C without a gap. Therefore, it is possible to prevent the end point detection window 3B from falling out of the through hole 3Ca of the polishing layer 3C during the polishing process of the object to be polished 2.
Further, as shown in FIGS. 5A to 5B, as the polishing process on the object to be polished 2 is repeated, the polishing surface 3A of the polishing layer 3C in the polishing pad 3 becomes FIG. 5 (a). ) Is worn down to the limit to be replaced shown in FIG. 5 (b).
When the polishing surface 3A is worn away, the depth of the groove 3Cd becomes relatively shallow, and when the depth of the groove 3Cd becomes shallow to a predetermined limit, it is time to replace the polishing layer 3C (FIG. 5B). Status). Even in that state, one bulging portion 3Ba below the bottom of the groove 3Cd remains without being worn and is engaged with the recess 3Cb. In other words, at least one bulging portion 3Ba remains in the end point detection window 3B even when the polishing layer 3C should be replaced. Therefore, according to this embodiment, it is possible to reliably prevent the end point detection window 3B from falling out of the through hole 3Ca of the polishing layer 3C during the polishing process of the object to be polished 2.

Next, FIG. 6A shows a second embodiment regarding the polishing layer 3C of the polishing pad 3. In this second embodiment, the screw 3Bf is formed on the outer peripheral surface of the end point detection window 3B, and the screw 3Bf is formed on the inner peripheral surface of the through hole 3Ca of the polishing layer 3C without any gap with the male screw 3Bf. An engaging female screw 3Cf is formed. The manufacturing method of the polishing layer 3C of the second embodiment is the same as the manufacturing method of the first embodiment shown in FIG.
There are three or more threads as convex portions of the male thread 3Bf in the axial direction (vertical direction), and at least one thread is present even when the groove 3Cd is shallow to the limit of replacement. Is supposed to remain. Other configurations are the same as those of the first embodiment shown in FIGS. 3 and 5 (a).
In this second embodiment as well, even if the polished surface 3A of the polishing layer 3C is in a state of being worn from the initial state shown in FIG. 6 (a) to the limit to be replaced shown in FIG. 6 (b), the male screw A plurality of threads as convex portions of 3Bf remain.
Therefore, even the polishing pad 3 provided with the polishing layer 3C of the second embodiment shown in FIG. 6A can obtain the same actions and effects as those of the first embodiment.

Next, FIG. 7A shows a third embodiment regarding the polishing layer 3C of the polishing pad 3. In this third embodiment, a square screw-shaped spiral protrusion 3Bg is formed on the outer peripheral surface of the end point detection window 3B, and in accordance with this, a spiral shape is formed on the inner peripheral surface of the through hole 3Ca of the polishing layer 3C. Recesses 3 Cg are formed, and they are in a state of being engaged without a gap.
The convex portions formed by the spiral protrusions 3Bg are formed at two or more positions in the vertical cross section in the axial direction (vertical direction). Further, at least one convex portion formed by the spiral protrusion 3Bg is formed below the bottom portion of the groove 3Cd. Other configurations are the same as those of the first embodiment shown in FIGS. 3 and 5 (a). The manufacturing method of the polishing layer 3C of the third embodiment is also the same as the manufacturing method of the first embodiment shown in FIG.
Also in this third embodiment, even if the polished surface 3A of the polishing layer 3C is in a state of being worn from the initial state shown in FIG. 7 (a) to the limit to be replaced shown in FIG. 7 (b), the spiral is formed. A plurality of convex portions of the spiral protrusion 3Bg remain.
Therefore, even the polishing pad 3 provided with the polishing layer 3C of the third embodiment shown in FIG. 7A can obtain the same actions and effects as those of the above-mentioned examples.

In the first embodiment shown in FIG. 3, a plurality of bulging portions 3Ba are formed in the end point detection window 3B, and a recess 3Cb is formed on the inner peripheral surface of the through hole 3Ca of the polishing layer 3C correspondingly. Although they are formed, the relationship between the irregularities may be reversed. That is, a plurality of recesses may be formed on the outer peripheral portion of the end point detection window 3B, and a bulging portion may be formed on the inner peripheral surface of the through hole 3Ca of the polishing layer 3C correspondingly. This relationship is the same for each of the examples disclosed in FIGS. 6 and 7 above.

1 Polishing device 2 Polished object 3 Polishing pad 3A Polished surface 3B End point detection window 3Ba Bout 3C Polishing layer 3Ca Through hole 3Cb Recess L1 Inspection light

Claims (6)

In a polishing pad provided with a polishing layer having a polishing surface for polishing an object to be polished and an end point detection window provided in a through hole of the polishing layer to transmit inspection light and reflected light from the object to be polished.
A plurality of convex portions are formed on the side portion of the end point detection window in a direction orthogonal to the polished surface.
A plurality of concave portions that engage with the convex portion of the end point detection window are formed on the inner peripheral surface of the through hole of the polishing layer.
A polishing pad characterized in that the convex portions and the concave portions at a plurality of locations are engaged with each other. A groove for holding and / or discharging the slurry is formed on the polished surface of the polishing layer, and is provided in a state where at least one convex portion and a concave portion are engaged below the height of the bottom portion of the groove. The polishing pad according to claim 1. 2. The convex portion is composed of a bulging portion formed on a side portion of a window for detecting an end point, and the concave portion is composed of a concave portion formed on an inner peripheral surface of a through hole of a polishing layer. Polishing pad described in. The polishing pad according to claim 2, wherein the convex portion is a male screw and the concave portion is a female screw. The polishing pad according to claim 2, wherein the pitch of the convex portions is 0.2 to 0.5 mm. The polishing pad according to claim 2, wherein the height of the convex portion is 0.15 to 0.5 mm.

Images