JP6985587B2 - Abrasive pad - Google Patents

Description

The present invention relates to a polishing pad, and more particularly to a polishing pad suitable for polishing an optical material, a glass substrate, or the like.

Conventionally, a polishing pad in which a plurality of concentric circumferential grooves are formed on a polishing surface and a plurality of linear grooves intersecting the circumferential grooves are known (for example, Patent Document 1 and Patent Document 2). ).
In such a conventional polishing pad, the circumferential groove is configured as a holding groove for holding the slurry, and the linear groove is configured as a discharge groove for discharging polishing debris and the slurry after use. The polishing pad of Patent Document 1 is configured so that the depth of the discharge groove is deeper than that of the holding groove, and the polishing pad of Patent Document 2 has a specific relationship between the pitch of the holding groove and the pitch of the discharge groove. It is set to, which improves the polishing rate.

Japanese Unexamined Patent Publication No. 2006-156876 Japanese Unexamined Patent Publication No. 2013-35108

By the way, in recent years, when polishing an object to be polished with a polishing pad, there is a demand for higher accuracy of polishing, and for that purpose, the following requirements are made for the polishing pad. That is, (1) the liquid slurry is evenly and sufficiently distributed on the surface of the object to be polished, (2) the consumption of expensive slurry is suppressed, and (3) the polishing debris that causes scratches is efficiently removed. It is required to control the flow of the slurry, such as discharging the slurry.
However, in the above-mentioned conventional polishing pad, the control of the slurry flow is not always sufficient. Further, in the polishing pad of Patent Document 1, although the slurry discharging capacity is excellent, the slurry holding capacity is not sufficient, and there is a problem that a high polishing rate cannot always be obtained.

In view of the above circumstances, the present invention includes a polishing surface that slides with the object to be polished, forms a circumferential groove along the circumferential direction on the polishing surface, and intersects the circumferential groove to form a polishing pad. A plurality of intersecting grooves are formed on the outer peripheral surface of the surface, the circumferential groove is configured as a holding groove for holding the slurry, and the plurality of intersecting grooves are used as a discharge groove for discharging polishing debris and used slurry. In the configured polishing pad
The depth of the circumferential groove as the holding groove is deeper than that of the intersecting groove as the discharging groove, and each intersecting portion where the holding groove and the discharging groove intersect accommodates and precipitates polishing debris. has become a housing portion,
The holding groove is composed of a plurality of circumferential grooves or spiral grooves concentrically arranged on the polished surface, and the discharge groove is characterized by being composed of a radial groove or a lattice groove formed on the polished surface. It is a thing.

According to such a configuration, the holding capacity of the slurry by the holding groove can be increased, and the polishing debris can be stored in the accommodating portion. Therefore, it is possible to provide a polishing pad having a high polishing rate by suppressing the generation of scratches.

The side view which shows the 1st Embodiment of this invention. The plan view of the polishing pad of FIG. A side view of the main part from the direction III of FIG. FIG. 2 is a cross-sectional view of a main part along the IV-IV line of FIG. An enlarged perspective view of a main part of FIG. 2. The plan view which shows the 2nd Embodiment of the polishing pad of this invention. The plan view which shows the 3rd Example of the polishing pad of this invention. FIG. 6 is a cross-sectional view showing another embodiment of the holding groove. FIG. 6 is a cross-sectional view showing another embodiment of the holding groove. FIG. 6 is a cross-sectional view showing another embodiment of the holding groove.

Hereinafter, the present invention will be described with respect to the illustrated examples. FIG. 1 shows a side view of the polishing apparatus 2 provided with the polishing pad 1 according to the present invention, in which the polishing apparatus 2 polishes the object to be polished 3 with the polishing pad 1. It is designed to do.
The polishing device 2 supplies a polishing surface plate 4 provided on the lower side to support the polishing pad 1, a support surface plate 5 provided on the upper side to support the object to be polished 3, and a liquid slurry S. It is provided with a slurry supply means 6.
The polishing pad 1 and the object to be polished 3 each have a substantially disk shape, and in this embodiment, the diameter of the polishing pad 1 is larger than the diameter of the object to be polished 3. The lower surface of the polishing pad 1 is fixed to the polishing surface plate 4 with double-sided tape or the like, and the object to be polished 3 is vacuum-sucked to the support surface plate 5.
Further, the polishing surface plate 4 and the support surface plate 5 are relatively rotated by a driving means (not shown), and the support surface plate 5 is provided so as to be reciprocating in the radial direction from the center position of the polishing surface plate 4. As a result, the polishing pad 1 and the object to be polished 3 slide while rotating relatively.
The slurry supply means 6 supplies a liquid slurry S in which abrasive grains are mixed in a required chemical to the central portion of the polishing surface 1A of the polishing pad 1, whereby the slurry S is the polishing surface 1A and the object to be polished. By entering between 3 and 3, the object to be polished 3 is polished.
The polishing apparatus itself having such a configuration is conventionally known, and further detailed description thereof will be omitted. In addition to the polishing device 2 having the above configuration, for example, the support platen 5 has no drive, and has other configurations such as a polishing device 2 in which the support plateau 5 is rotated by the rotation of the polishing surface plate 4. The polished polishing device 2 can also be used.

As a method for producing the polishing pad 1 of the present embodiment, for example, a preparatory step for preparing at least a polyurethane bond-containing isocyanate compound as a prepolymer, a curing agent, and a hollow body; at least the above polyurethane bond-containing isocyanate compound and a curing agent are mixed. A mixing step of obtaining a mixed solution for molding a molded body; a molded body molding step of molding a polyurethane polyurea resin molded body from the mixed solution for molding a molded body; and having the polished surface 1A from the polyurethane polyurea resin molded body. It may include a polishing layer forming step of forming a polishing layer.
Hereinafter, each of the preparation step, the mixing step, the molded body molding step, and the polishing layer forming step will be described separately.

As the preparatory step, for the production of the polishing pad 1, 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 body. Further, the 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 normally 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-phenylene diisocyanate, p-phenylenedi isocyanate, 2,6-toluene diisocyanate (2,6-TDI), and 2,4-toluene 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, trimethylene diisocyanate, hexamethylene diisocyanate, propylene -1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylenediisothiocianate, xylylene-1,4-diisocyanate, Ethylidine diisocyanate and the like can be mentioned.
Further, as the polyisocyanate compound, a diisocyanate compound is preferable, 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 above-mentioned 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-mentioned polyol compound may be used alone or in combination of a plurality of polyol compounds.

Here, the NCO equivalent of the prepolymer indicating the molecular weight of PP (prepolymer) per NCO group is preferably 200 to 800, more preferably 300 to 700, and 400 to 600. Is even more preferable.
Specifically, the NCO equivalent of the above prepolymer can be obtained 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 (also referred to as a chain extender), 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 an amine compound include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, and di-2-hydroxy. Examples thereof include ethyl propylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine 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 body forming 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 (chain extender), 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, and 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-mentioned polyol compound may be used alone or in combination of a plurality of polyol compounds.

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 0.1.30, more preferably 0.70 to 1.20.

The hollow body means a microsphere having a void. Microspheres include spherical, elliptical, and similar shapes. As an example of the hollow body, 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 is heated and expanded. Can be mentioned.
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 polyurethane polyurea resin molded body is molded by pouring the mixed solution for molding body molding prepared in the above mixing step into a mold at 50 to 100 ° C. and curing it.
At this time, the prepolymer and the curing agent react to form a polyurethane polyurea resin, so that the mixed solution is cured.

Then, in the polishing layer forming step, the polyurethane polyurea resin molded body obtained in the above-mentioned molded body molding step is sliced into a sheet, and the sliced resin sheet is cut into a circle to form a disk-shaped polishing pad 1. The upper surface on one side is the polished surface 1A, and the lower surface on the opposite side is the mounting surface for the double-sided tape described above.

The disk-shaped polishing pad 1 is manufactured through the above-mentioned steps. Further, in this embodiment, a plurality of holding grooves 1B for holding the slurry S are formed on the polishing surface 1A which is the upper surface of the polishing pad 1 and polishing is performed. A plurality of discharge grooves 1C for discharging the waste and the slurry S after use are formed.
That is, as shown in the plan view of FIG. 2, a plurality of circumferential grooves are formed concentrically from the center of the polishing surface 1A of the polishing pad 1 at equal pitches P, and each circumferential groove is formed. It is a holding groove 1B for holding the slurry S. Each holding groove 1B formed in the circumferential direction is not open to the outer peripheral surface 1D of the polishing pad 1 and has a closed shape. The width and depth of each circumferential groove as the holding groove 1B are all the same size. As shown in FIGS. 4 to 5, the cross-sectional shape of the holding groove 1B is a vertically long rectangle.
Further, a plurality of linear radial grooves extending in the radial direction from the center and opening in the outer peripheral surface 1D are formed on the polished surface 1A, and each radial groove is a discharge groove 1C. The discharge grooves 1C are formed at a total of 16 locations at equal angles in the circumferential direction, and each of the discharge grooves 1C is substantially orthogonal to the holding groove 1B formed of the circumferential groove (FIG. FIG. 2 to FIG. 5). The discharge groove 1C formed of the radial groove is an intersecting groove that intersects with the holding groove 1B. The cross-sectional shape of the discharge groove 1C is a horizontally long rectangle. Then, as shown in FIG. 5, the width of the discharge groove 1C is set to a dimension approximately three times the width of the holding groove 1B. The width of the discharge groove 1C may be set to about 2 to 10 times the width of the holding groove 1B.
Further, as shown in FIGS. 3 to 5, the depth of the holding groove 1B is deeper than that of the discharge groove 1C. More specifically, the depth of the holding groove 1B is set to about twice the depth of the discharging groove 1C. The depth of the holding groove 1B may be set to about 1.1 to 3 times the depth of the discharging groove 1C.
As shown in FIG. 5, in each intersecting portion where the holding groove 1B and the discharging groove 1C intersect, the bottom portion 1Ba of the holding groove 1B also serves as the bottom portion 1Ca of the discharging groove 1C, and each of these intersecting portions serves as polishing debris. It is a storage unit 1E that stores and precipitates.

As described above, in the polishing pad 1 of the present embodiment, a plurality of holding grooves 1B are formed on the polishing surface 1A, and a plurality of discharge grooves 1C as crossing grooves intersecting the holding grooves 1B are formed. The depth of 1B is deeper than that of the discharge groove 1C. In other words, since the discharge groove 1C has a shallower depth than the holding groove 1B, the discharge amount of the slurry S during the polishing operation can be appropriately suppressed.
Therefore, when the slurry S is supplied to the central portion of the polishing surface 1A and the object to be polished 3 is polished by the polishing pad 1, the holding ability of the holding groove 1B of the polishing surface 1A to hold the slurry S is increased. As a result, the slurry S of the holding groove 1B is evenly supplied to the sliding portion between the polishing surface 1A and the object to be polished 3, and the object to be polished 3 is polished by the polishing surface 1A in that state.
Then, the polishing debris generated during the polishing operation and the slurry S after use are discharged outward in the radial direction of the polishing surface 1A through the respective discharge grooves 1C. At that time, the polishing debris moving in the discharge groove 1C falls into each of the accommodating portions 1E, is accommodated therein, and precipitates (see FIGS. 4 and 5). In this way, since the polishing debris is contained in each accommodating portion 1E and settles, it is possible to suppress the generation of scratches due to the polishing debris.
According to this embodiment, the holding groove 1B can improve the holding ability to hold the slurry S, and the polishing debris can be stored in the accommodating portion 1E. Therefore, it is possible to provide the polishing pad 1 having a high polishing rate by suppressing the generation of scratches.

Next, FIG. 6 shows a second embodiment of the polishing pad 1, and in this second embodiment, a grid-like groove is formed on the polishing surface 1A instead of the radial groove in the first embodiment described above. It is a feature that it was done. In this second embodiment, the grid-like groove is the discharge groove 1C. Other configurations are the same as those of the polishing pad 1 of the first embodiment shown in FIG. 2, and the corresponding portions are numbered the same. Even with the polishing pad 1 of the second embodiment having such a configuration, the same operations and effects as those of the first embodiment described above can be obtained.

Next, FIG. 7 shows a third embodiment of the polishing pad 1. In this third embodiment, a single spiral groove 1F is formed in place of the plurality of circumferential grooves in the first embodiment shown in FIG. The spiral groove 1F is a circumferential groove along the circumferential direction. The outer end 1F of the spiral groove 1F is not open to the outer peripheral surface 1D of the polishing pad 1, and therefore the spiral groove 1F is a circular groove having a closed shape. Other configurations are the same as those of the first embodiment shown in FIG. 2 above. In this third embodiment, the entire spiral groove 1F is the holding groove 1B, and each intersecting portion where the spiral groove 1F and the discharge groove 1C (radiation direction groove) intersect is the accommodating portion 1E. The parts corresponding to the polishing pad 1 of the first embodiment in the third embodiment are designated with the same member numbers. Even with the polishing pad 1 of the third embodiment having such a configuration, the same operations and effects as those of the first embodiment described above can be obtained.

Next, FIGS. 8 to 10 show another embodiment regarding the cross-sectional shape of the holding groove 1B. That is, FIG. 8 shows a linear rectangular groove formed along the longitudinal direction at the center of the bottom portion 1Ba of the holding groove 1B of FIG. As a result, the holding groove 1B has a cross-sectional shape in which a small square recess is formed in the center of the bottom.
Next, FIG. 9 shows a trapezoidal cross-sectional shape of the holding groove 1B. Further, in FIG. 10, the width of the holding groove 1B on the bottom 1Ba side is formed in a square shape wider than the upper portion, whereby the cross section is convex as a whole. In the holding groove 1B shown in FIGS. 9 and 10, the groove width of the bottom portion 1Ba is wider than that on the upper side. Therefore, the amount of polishing debris accommodated in the accommodating portion 1E can be increased, and the polishing debris accommodated in the accommodating portion 1E is less likely to flow out to the polishing surface 1A.
The polishing pad 1 having the holding grooves 1B of FIGS. 8 to 10 has a structure in which a large amount of polishing debris is accommodated in the accommodating portion 1E and it is difficult for the polishing pad 1 to flow out from the accommodating portion 1E.

In the first embodiment and the second embodiment, a plurality of concentrically formed circumferential grooves are formed on the polished surface 1A, and these are used as holding grooves 1B. However, the grooves are formed along the circumferential direction. A plurality of octagons concentrically formed on the polished surface 1A may be formed as the holding groove 1B. Even with the plurality of octagonal circumferential grooves thus formed, the same effect as that of the above embodiment in which the holding groove 1B composed of the circumferential grooves can be obtained can be obtained.
Further, instead of the radial grooves and the grid-like grooves in the above embodiment, a plurality of parallel linear grooves may be formed on the polished surface 1A as the discharge grooves 1C. Further, the discharge groove 1C is not limited to the linear groove, and a plurality of arcuate grooves may be formed on the polished surface 1A so as to intersect the holding groove 1B.
Further, in the first to third embodiments, the cross-sectional shapes of the holding groove 1B and the discharging groove 1C are square, but the cross-sectional shape of either the holding groove 1B or the discharging groove 1C may be V-shaped. good.

1 Polishing pad 1A Polished surface 1B Holding groove 1C Discharge groove 1E Accommodating part S Slurry

Claims (3)

A polishing surface that slides with the object to be polished is provided, and a circumferential groove is formed on the polishing surface along the circumferential direction, and a plurality of intersecting grooves that intersect the circumferential groove and open on the outer peripheral surface of the polishing pad. In the polishing pad, the circumferential groove is configured as a holding groove for holding the slurry, and the plurality of intersecting grooves are configured as the discharging groove for discharging the polishing debris and the used slurry.
The depth of the circumferential groove as the holding groove is deeper than that of the intersecting groove as the discharging groove, and each intersecting portion where the holding groove and the discharging groove intersect accommodates and precipitates polishing debris. has become a housing portion,
The holding groove is composed of a plurality of circumferential grooves or spiral grooves concentrically arranged on the polished surface, and the discharge groove is characterized by being composed of a radial groove or a lattice groove formed on the polished surface. Polishing pad. The first aspect of the present invention is characterized in that the width of the holding groove is narrower than the width of the discharging groove, and the depth of the holding groove is about twice the depth of the discharging groove. The described polishing pad. The cross section of the discharge groove is square or V-shaped, and the cross section of the holding groove is square, V-shaped, square with a recess in the center of the bottom, trapezoidal, or convex with the bottom side wider than the upper part. The polishing pad according to claim 2 , wherein the polishing pad is any of the above.

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