JP2021053758A - Polishing pad - Google Patents

Abstract

To provide a polishing pad having an endpoint detection window that prevents the occurrence of scratches on a polishing object and prevents polishing chips and slurry from accumulating.SOLUTION: A polishing pad has a polishing layer having an endpoint detection window in part of it. The endpoint detection window is composed of a material to expand in volume when in a wet state.SELECTED DRAWING: Figure 1

Description

The present invention relates to a polishing pad. More specifically, the present invention relates to a polishing pad that can be suitably used for polishing optical materials, semiconductor wafers, semiconductor devices, substrates for hard disks, and the like.

A chemical mechanical polishing (CMP) method is generally used as a polishing method for flattening the surfaces of optical materials, semiconductor wafers, semiconductor devices, and substrates for hard disks.

The CMP method will be described with reference to FIG. As shown in FIG. 1, the polishing apparatus 1 that carries out the CMP method is provided with a polishing pad 3, and the polishing pad 3 is a layer that comes into contact with the object to be polished 8 held by the holding surface plate 16 to perform polishing. The polishing layer 4 and the cushion layer 6 supporting the polishing layer 4 are included. The polishing pad 3 is rotationally driven in a state where the object 8 to be polished is pressed, and polishes the object 8 to be polished. At that time, the slurry 9 is supplied between the polishing pad 3 and the object to be polished 8. The slurry 9 is a mixture (dispersion liquid) of water and various chemical components and hard fine abrasive grains, and the polishing effect is obtained by the relative movement with the object to be polished 8 while the chemical components and abrasive grains in the mixture are being washed away. Is to increase. The slurry 9 is supplied to the polished surface through a groove or a hole and discharged.

In the CMP method, it can be confirmed by an optical method whether the object to be polished 8 has been polished to a desired position. For example, the polishing apparatus 1 shown in FIG. 1 includes an optical sensor 14 and the like for confirming the end point. Specifically, an end point detection window 5 having translucency is provided in a part of the polishing pad 3, and a light source 13 and an optical sensor 14 are provided under the polishing surface plate 10.

The principle of detecting the end point by an optical method will be described with reference to FIG. When the light 2 emitted by the light source 13 is incident on the thin film (for example, an insulating film) 12 formed on the substrate 11 which is the object to be polished 8, a part of the light 2a is reflected on the surface of the thin film 12, while the light 2a is reflected on the surface of the thin film 12. , Another light 2b passes through the thin film 12 and is reflected on the surface of the object 8 to be polished. The reflected light 2a and 2b are detected by the optical sensor 14 through the end point detection window 5, and the phase difference and the intensity of the reflected light are generated according to the thickness of the thin film 12, and the phase difference and the change in the reflected intensity are detected. Therefore, the polishing status of the thin film 12 can be confirmed.

Normally, the end point detection window 5 provided on the polishing pad 3 wears together with the polishing layer 4 during polishing. As shown in FIG. 5, when the end point detection window 51 is made of a material having high wear resistance, the polishing layer 41 is worn faster than the end point detection window 51, so that the surface 51a of the end point detection window is the polishing layer 41. There is a problem that the polishing performance is affected, for example, the surface becomes higher than the surface 41a, a lump (protrusion) is formed, and the end point detection window 51 causes scratches on the object to be polished 8.

Therefore, conventionally, various measures have been taken in order to prevent the formation of a lump of the end point detection window 5 in the polishing layer 4. For example, Patent Document 1 discloses a polishing pad that increases the wear rate of the window portion during a polishing operation by dispersing dispersed particles over the entire end point detection window and prevents the formation of a mass of the end point detection window in the polishing layer. ing. Since the wear rate of the end point detection window is higher than that of the polishing layer, the end point detection window does not protrude from the surface of the polishing layer, and scratches on the polishing layer by the end point detection window are less likely to be formed.

Special Table 2003-526938

However, in the polishing pad described in Patent Document 1, as shown in FIG. 6, since the wear rate of the end point detection window 52 is increased, the end point detection window 52 is removed by wearing more than the polishing layer 42, and the end point detection window 52 The surface 52a is lower than the surface 42a of the polishing layer 42, and a dent is generated in the polishing layer 42. In that case, foreign matter 15 such as abrasive grains and polishing debris contained in the slurry may accumulate at the boundary between the polishing layer 42 formed by denting and the end point detection window 52, which may affect the detection accuracy of reflected light. is there.

Therefore, an object of the present invention is to provide a polishing pad in which scratches are suppressed and polishing debris and slurry are less likely to accumulate by using a material that softens only the surface in contact with the end point detection window when it comes into contact with slurry or water. And.

As a result of intensive research, the present inventors have been able to soften only the surface of the end point detection window in contact with the slurry by using a material that softens in a wet state as the material of the end point detection window. As a result, it was discovered that the wear rate becomes equivalent to that of the polishing layer and the window by polishing, and the surface can suppress the formation of irregularities, and the present invention can be reached. That is, the present invention includes the following.
[1] A polishing pad having a polishing layer partially provided with an end point detection window, wherein the end point detection window is made of a material whose volume expands when infiltrated.
[2] The polishing pad according to [1], wherein the D hardness of the material of the end point detection window in a wet state is lower than the D hardness in a dry state.
[3] The polishing pad according to [1] or [2], wherein the end point detection window is polyurethane, polyurea or polyurethane polyurea containing sodium polyacrylate as an additive.

The polishing pad provided with the end point detection window of the present invention can optically check the polishing status, and the surface of the end point detection window absorbs slurry and water to swell and decrease in hardness. It wears together with the polishing layer without causing scratches on the object to be polished. Further, since the hardness of the inside of the end point detection window that does not come into contact with the slurry or water is maintained, the end point detection window is not dented as compared with the polishing layer, so that polishing debris and slurry do not collect in the end point detection window. , Deterioration of detection accuracy can be suppressed.

FIG. 1 is a perspective view of the polishing apparatus 1. FIG. 2 is a schematic view showing the paths of incident light and reflected light. FIG. 3 is a perspective view of the polishing pad 3 of the present invention. FIG. 4 is a cross-sectional view (AA'cross-sectional view) of the polishing pad 3 of the present invention. FIG. 5 is a cross-sectional view of a polishing pad having a high hardness of the end point detection window. FIG. 6 is a cross-sectional view of a polishing pad having a low hardness of the end point detection window. FIG. 7 is a schematic view showing a method for manufacturing the polishing pad 3 of the present invention.

Hereinafter, embodiments for carrying out the invention will be described, but the present invention is not limited to the embodiments for carrying out the invention.

<< Polishing pad >>
The structure of the polishing pad 3 will be described with reference to FIG. As shown in FIG. 3, the polishing pad 3 provided in the polishing apparatus 1 has a polishing layer having at least one end point detection window 5 (in FIG. 3, including two end point detection windows 5) penetrating the polishing pad 3. 4 and the cushion layer 6 are included. Since the polishing pad 3 has the end point detection window 5, the polishing status of the object to be polished 8 can be optically confirmed by using the light source 13 and the optical sensor 14.
The shape of the polishing pad 3 is preferably disc-shaped, but is not particularly limited, and the size (diameter) can be appropriately determined according to the size of the polishing device 1 provided with the polishing pad 3 and the like. For example, the diameter can be about 10 cm to 1 m.
The polishing pad 3 of the present invention preferably has the polishing layer 4 bonded to the cushion layer 6 via the adhesive layer 7, but may be composed of only the polishing layer 4.
The polishing pad 3 is attached to the polishing surface plate 10 of the polishing apparatus by a double-sided tape or the like arranged on the cushion layer 6. The polishing pad 3 is rotationally driven in a state where the object to be polished 8 is pressed by the polishing device to polish the object to be polished.

<Abrasive layer>
The polishing pad 3 includes a polishing layer 4 which is a layer for polishing an object to be polished. As the material constituting the polishing layer 4, a polyurethane resin, a polyurea resin, and a polyurethane polyurea resin can be preferably used, and more preferably, a polyurethane resin can be used.
The size (diameter) of the polishing layer 4 is the same as that of the polishing pad 3, and the diameter can be about 10 cm to 2 m, and the thickness of the polishing layer 4 can be usually about 1 to 5 mm.
The polishing layer 4 is rotated together with the polishing surface plate 10 of the polishing apparatus 1, and while flowing the slurry 9 on the polishing platen 10, the chemical components and abrasive grains contained in the slurry are relatively moved together with the object to be polished 8. The object 8 to be polished is polished. By applying concentric, grid-like, radial and other groove processing to the surface of the polishing layer 4, the retention and discharge of the slurry 9 can be adjusted, and the polishing characteristics can be changed.

<End point detection window>
The polishing layer 4 has at least one end point detection window 5. The end point detection window 5 has translucency because it is for confirming the end point of polishing by optical means. Therefore, it is preferable that the end point detection window 5 has high translucency. Further, the end point detection window 5 of the present invention has a feature of absorbing slurry and water to swell and soften. That is, the surface of the end point detection window 5 in contact with the slurry 9 or the like becomes soft, but the inside remains hard. By softening only the surface of the end point detection window 5, the softened portion wears during polishing, and the inside maintains hardness, so that the inside is not suddenly and greatly worn. In addition, when it comes into contact with slurry or water, it may swell and the surface of the end point detection window 5 may be higher than the surface of the polishing layer 4, but even in that case, the hardness of the swelled portion decreases. Therefore, due to wear, the height becomes about the same as that of the polishing layer 4.
By providing such an end point detection window 5, the problem that the object to be polished is damaged by the end point detection window as in the conventional case is eliminated, while the end point detection window is softened and dents are generated to generate polishing debris and slurry. The problem of accumulating in dents is also eliminated. That is, it is possible to suppress the occurrence of scratches and minimize the influence on the detection accuracy.
Normally, the number of end point detection windows 5 may be one or more. The diameter of the end point detection window 5 is preferably about 1 cm to 15 cm, and the thickness is the same as that of the polishing layer 4, and is usually about 1 to 5 mm. Details of the end point detection window 5 will be described in the section << Manufacturing method of end point detection window >>.

The end point detection window 5 generally has a columnar shape that penetrates the upper surface and the lower surface of the polishing layer 4, but is particularly limited as long as it penetrates the upper surface and the lower surface of the polishing layer 4. It is not a thing, but a square prism type, a triangular prism type, etc. can be appropriately selected.

<Cushion layer>
Since the cushion layer 6 is composed of an impregnated non-woven fabric impregnated with resin, a flexible material such as synthetic resin, a foam having a bubble structure, and the like, the polishing layer 4 is brought into contact with the object to be polished 8. It can be made more uniform. In the present invention, the polishing pad 3 may be composed of only the polishing layer 4, but it is preferably adhered to the cushion layer 6.
Further, in the cushion layer 6, the same number of holes as the end point detection window 5 are formed in the portion corresponding to the installation position of the end point detection window 5 so that light for performing light detection can pass through. is required.

<Adhesive layer>
The adhesive layer 7 is a layer for adhering the cushion layer 6 and the polishing layer 4, and is usually composed of double-sided tape or an adhesive. As the double-sided tape or adhesive, those known in the art can be used.

<Abrasive device>
As described above, the polishing apparatus 1 provided with the polishing pad 3 of the present invention can confirm the polishing state by optical means. For example, as shown in FIG. 1, the polishing surface plate 10 having the polishing device 1 includes a light source 13 and an optical sensor 14. The light emitted from the light source 13 passes from the bottom to the top of the polishing surface plate 10, further passes through the hole of the cushion layer 6, and further passes through the end point detection window 5 of the polishing pad 3, and the object to be polished 8 The optical sensor 14 senses the light that arrives at and is reflected by the object to be polished 8 and returned. By rotating the light source 13 and the optical sensor 14 together with the polishing surface plate 10 in this way, the polishing status can be confirmed while polishing.

<< Manufacturing method of end point detection window >>
The method for manufacturing the end point detection window of the present invention will be described.

<Material of end point detection window>
The material of the end point detection window 5 is not particularly limited as long as it is a material in which the portion in contact with the slurry or water swells and the hardness decreases, and the material has translucency. Since the end point detection window 5 may be required to have the same function as the polishing layer 4, that is, the function of polishing the object 8 to be polished, the main component is preferably the same as that of the polishing layer 4. That is, the main components of the material of the end point detection window 8 are preferably polyurethane resin, polyurea resin, and polyurethane polyurea resin, and more preferably polyurethane resin. Specific examples of the main component material include a material obtained by reacting a urethane bond-containing polyisocyanate compound with a curing agent.

The end point detection window 5 can contain an additive for making a material in which the portion in contact with water swells and the hardness decreases. Examples of such additives include water-absorbent polymers, and for example, polyacrylate-based, polysulfone-based, maleic anhydride-based, polyacrylamide-based, polyvinyl alcohol-based, polyethylene oxide-based, and the like are used. Can be done. Among these, sodium polyacrylate and polylactic acid can be preferably used. The content of the above additive is 10% or less, preferably 1 to 5%, of the total weight of the components constituting the end point detection window 5.

The end point detection window 5 absorbs water and swells when the surface of the end point detection window 5 comes into contact with the water of the slurry by adding a water-absorbing polymer as an additive. The hardness of the swollen portion is lower than that of the unswollen portion. Hereinafter, the degree of swelling indicating the degree of swelling and the D hardness indicating the degree of softening will be described.

(Swelling degree)
In the present specification, the degree of swelling means the amount of change in weight of the material (polymer) before and after water absorption. In the present invention, it is desirable that the surface of the end point detection window 5 in contact with the object to be polished 8 has the same height as the surface of the polishing layer 4 in contact with the object 8 to be polished. The degree of swelling is preferably 0 to 30%, more preferably 2 to 25%, and even more preferably 5 to 20%.
In this specification, the degree of swelling can be measured by the weight of the end point detection window 5 before and after immersion in water. The end point detection window 5 is cut out into a square of 4 cm × 4 cm to make a sample, and the weight after standing for 12 hours under the conditions of temperature 23 ° C. (± 2 ° C.) and humidity 50% (± 5%) is put on a precision balance. To measure. Next, this sample is immersed in distilled water, soaked in water for 30 minutes, then the sample is taken out, only the water on the surface is wiped off, and the weight of the sample after being immersed in water is measured with a precision balance. Using these weight values, the degree of swelling of the surface layer of the polishing sheet is calculated by the following formula.
Swelling degree (%) = (sample weight after immersion in water-sample weight before immersion in water) / sample weight before immersion in water x 100

(D hardness)
In the present specification, the D hardness (type D) indicates the hardness of a material (polymer). In the present invention, since it is necessary for the end point detection window 5 to absorb water and soften, the D hardness of the end point detection window 5 in the wet state is lower than the D hardness in the dry state. Specifically, the lower limit of the difference in D hardness between the wet state and the dry state is preferably 5 or more, more preferably 10 or more, and further preferably 15 or more. The upper limit is not particularly limited, but is, for example, 30 or less.
Further, when the surface of the end point detection window 5 is softened, it is desirable to have the same degree of wear resistance as the surface of the polishing layer 4, and the upper limit of the difference in D hardness between the polishing layer 4 and the end point detection window 5 in a wet state is It is preferably 25 or less, more preferably 23 or less, and even more preferably 20 or less. The lower limit is not particularly limited, but is, for example, 5 or more.
The D hardness can be measured by using a D-type hardness tester (GS702) manufactured by Teclock Co., Ltd. according to JISK6253-1997 / ISO7619. Specifically, the wet D hardness of the end point detection window 5 is measured by immersing the end point detection window 5 in deionized water at 40 ° C. for 30 minutes, taking out the wet end point detection window, lightly wiping off the moisture with a filter paper, and immediately starting the measurement. The end point detection window is set to have a thickness of at least 4.5 mm or more. The D hardness is read 2 seconds after the pressure plate is brought into contact with the sample.

(Wear rate)
In the present specification, the wear rate means the amount of wear removed in a fixed time unit. In the present invention, it is desirable that the wear rates of the end point detection window 5 and the polishing layer 4 are about the same, and the difference between the wear rates of the polishing layer 4 and the end point detection window 5 is preferably 10 to 300. It is more preferably 270, and even more preferably 30 to 250.
The wear rate was evaluated by the wear reduction by the Taber wear test of the polishing layer and the end point detection window. Abrasion weight loss shall be performed by a method according to the Taber wear test of Japanese Industrial Standards (JIS K 6902), and measured using 320-count sandpaper while dropping water at 40 ° C. on the polishing layer and the end point detection window. Can be done.

(Transmittance)
Since the end point detection window 5 allows light to pass through, it is preferable that the end point detection window 5 has a high transmittance at 300 to 800 nm, which is frequently used. For example, the transmittance of light at 660 nm is preferably 50% or more, more preferably 60% or more, still more preferably 70% or more, and even more preferably 80% or more. If the transmittance is high, errors are unlikely to occur and measurement can be performed with high accuracy. The transmittance can be measured using a spectrophotometer (U-3210 Spectro Photometer manufactured by Hitachi, Ltd.), and the sample thickness at this time is 10 mm.

Hereinafter, the method for producing the material of the end point detection window 5 will be described by taking an end point detection window using a urethane bond-containing isocyanate compound, a polyol compound and a curing agent as an example.

As a method for manufacturing the end point detection window 5 using the urethane bond-containing polyisocyanate compound and the curing agent, for example, a material preparation step for preparing at least the urethane bond-containing polyisocyanate compound, the additive, and the curing agent; at least the urethane bond. Examples thereof include a manufacturing method including a mixing step of mixing the contained polyisocyanate compound, an additive, and a curing agent to obtain a mixed solution for molding a molded body; and a curing step of molding an end point detection window from the mixed solution for molding a molded body. ..

Hereinafter, each of the material preparation step, the mixing step, and the molding step will be described separately.

<Material preparation process>
For the production of the end point detection window 5 of the present invention, a urethane bond-containing polyisocyanate compound and a curing agent are prepared as raw materials for the polyurethane resin molded product (curing resin). In addition, a water-absorbent polymer is also prepared as an additive. Here, the urethane bond-containing polyisocyanate is a urethane prepolymer for forming a polyurethane resin molded product. When the end point detection window 5 is made of a polyurea resin molded product or a polyurethane polyurea resin molded product, a corresponding prepolymer is used.

Hereinafter, each component will be described.

(Urethane bond-containing polyisocyanate compound)
The urethane bond-containing polyisocyanate compound (urethane prepolymer) is a compound obtained by reacting the following polyisocyanate compound and a polyol compound under commonly used conditions, and contains a urethane bond and an isocyanate group in the molecule. Further, other components may be contained in the urethane bond-containing polyisocyanate compound as long as the effects of the present invention are not impaired.

As the urethane bond-containing polyisocyanate 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 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.

(Polyisocyanate compound)
As used herein, 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, 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. These polyisocyanate compounds may be used alone or in combination of a plurality of polyisocyanate compounds.

The polyisocyanate compound preferably contains 2,4-TDI and / or 2,6-TDI, and more preferably contains 2,4-TDI and 2,6-TDI. Even more preferably, it consists of only 2,4-TDI and 2,6-TDI. The mass ratio of 2,4-TDI to 2,6-TDI is preferably 100: 0 to 50:50, more preferably 90: 10 to 60:40, and 90: 10 to 70:30. Is even more preferably 80:20.

(Polypolymer compound as a raw material for prepolymer)
As used herein, the polyol compound means a compound having two or more hydroxyl groups (OH) in the molecule.
Examples of the polyol compound used for synthesizing the urethane bond-containing polyisocyanate compound as a prepolymer include diol compounds such as ethylene glycol, diethylene glycol (DEG) and butylene glycol, triol compounds and the like; poly (oxytetramethylene) glycol (or Polyether polyol compounds such as polytetramethylene ether glycol) (PTMG) can be mentioned. Among these, PTMG is preferable. The number average molecular weight (Mn) of PTMG is preferably 500 to 2000, more preferably 600 to 1300, and even more preferably 650 to 1000. The number average molecular weight can be measured by gel permeation chromatography (GPC). When measuring the number average molecular weight of a polyol compound from a polyurethane resin, it can be estimated by GPC after decomposing each component by a conventional method such as amine decomposition.
The above polyol compound may be used alone, or a plurality of polyol compounds may be used in combination.

(Additive)
As described above, a super absorbent polymer can be used as an additive as the material of the end point detection window 5. The mixing method is not particularly limited, but is usually mixed with a polyisocyanate compound or the like. As the material, polyacrylate-based, polysulfonate-based, maleic anhydride-based, polyacrylamide-based, polyvinyl alcohol-based, polyethylene oxide-based, and the like can be used, and for example, sodium polyacrylate and polylactic acid are used. be able to.

(Hardener)
In the method for producing the end point detection window 5 of the present invention, a curing agent (also referred to as a chain extender) is mixed with a urethane bond-containing polyisocyanate compound or the like in the mixing step. By adding the curing agent, in the subsequent molding step of the molded product, the main chain end of the urethane bond-containing polyisocyanate compound is bonded to the curing agent to form a polymer chain and is cured.
Examples of the curing agent include ethylenediol, propylenediol, hexamethylenediol, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), and 4-methyl. -2,6-bis (methylthio) -1,3-benzenediol, 2-methyl-4,6-bis (methylthio) -1,3-benzenediol, 2,2-bis (3-amino-4-hydroxy) Diol) 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, Polyvalent amine compounds such as trimethylethylenebis-4-aminobenzonate and polytetramethylene oxide-di-p-aminobenzonate; ethylene glycol, propylene 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-dimethyltrimethylethylene 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, Examples thereof include polyhydric alcohol compounds such as neopentyl glycol, glycerin, trimethylolpropane, trimethylolethane, trimethylolmethane, poly (oxytetramethylene) glycol, polyethylene glycol, and polypropylene glycol. Further, the polyvalent amine compound may have a hydroxyl group, and examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, and di-2. -Hydroxyethyl propylenediamine, 2-hydroxypropyl ethylenediamine, di-2-hydroxypropyl ethylenediamine and the like can be mentioned. As the polyvalent amine compound, a diamine compound is preferable, and for example, 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (hereinafter, abbreviated as MOCA) is further used. preferable.

<Mixing process>
In the mixing step, the urethane bond-containing polyisocyanate compound (urethane prepolymer), the additive, and the curing agent obtained in the preparatory step are supplied into the mixer and stirred and 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.
In the mixing step, at least a urethane bond-containing polyisocyanate compound (urethane prepolymer), an additive, and a curing agent are supplied into the mixer and stirred / mixed. The mixing order is not particularly limited, but a urethane bond-containing polyisocyanate compound and a mixed solution in which a curing agent, an additive, and other components are mixed if necessary are prepared, and both are supplied into a mixer and mixed. Stirring is preferred. In this way, a mixed solution for molding a molded product is prepared. 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.

<Molding process>
In the molded body molding step, the mixed solution for molding body molding prepared in the mixing step is poured into a rod-shaped mold preheated to 30 to 100 ° C. and first cured, and then 10 minutes to 5 minutes at about 100 to 150 ° C. A cured polyurethane resin (polyurethane resin molded product) is molded by heating for about an hour and secondary curing. At this time, the urethane prepolymer and the curing agent react to form a polyurethane resin, so that the mixed solution is cured.
By providing the mold with irregularities and a thread cutting structure, it is possible to prevent the end point detection window 5 from coming off from the formed polishing layer 4.

<About transmittance>
If the end point detection window 5 contains air bubbles, it is considered that the light from the light source 13 is reflected by the air bubbles, the light transmittance is lowered, and the accuracy of end point detection is affected. Therefore, in order to prevent the end point detection window 5 from containing air bubbles, for example, sufficient decompression defoaming may be performed at the stage of preparing the material.

<< Manufacturing method of polishing layer >>
The method for producing the polishing layer 4 of the present invention will be described. The material of the polishing layer 4 is not particularly limited as long as it can be used for polishing, but for example, a polyurethane resin material obtained by reacting a urethane bond-containing polyisocyanate compound with a curing agent can be used. Can be used.

The polishing layer 4 is preferably a polyurethane resin material having bubbles. Further, the bubbles of the polyurethane resin material are classified into closed cells in which a plurality of cells independently exist and open cells in which a plurality of cells are connected by communication holes, depending on the embodiment. Among these, the polyurethane resin material used in the present invention preferably has closed cells, and more preferably a polyurethane resin material containing the polyurethane resin and hollow fine particles dispersed in the polyurethane resin.

The polyurethane resin material having closed cells can be molded by using hollow fine particles having an outer shell and a hollow inside. As the hollow fine particles, commercially available ones may be used, or those obtained by synthesizing by a conventional method may be used. The material of the outer shell of the hollow fine particles is not particularly limited, and for example, polyvinyl alcohol, polyvinylpyrrolidone, poly (meth) acrylic acid, polyacrylamide, polyethylene glycol, polyhydroxyether acrylite, maleic acid copolymer, and polyethylene oxide. , Polyurethane, poly (meth) acrylonitrile, polyvinylidene chloride, polyvinyl chloride and organic silicone-based resins, and copolymers in which two or more kinds of monomers constituting these resins are combined. The hollow fine particles on the market are not limited to the following, and examples thereof include the Expandel series (trade name manufactured by Akzo Nobel) and Matsumoto Microsphere (trade name manufactured by Matsumoto Yushi Co., Ltd.). ..

The shape of the hollow fine particles in the polyurethane sheet is not particularly limited, and may be spherical or substantially spherical, for example. The average particle size of the hollow fine particles is not particularly limited, but is preferably 5 to 200 μm, more preferably 5 to 80 μm, still more preferably 5 to 50 μm, and particularly preferably 5 to 35 μm. The average particle size can be measured by a laser diffraction type particle size distribution measuring device (for example, Mastersizer-2000 manufactured by Spectris Co., Ltd.).

The hollow fine particles are added in an amount of preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass, and even more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the urethane prepolymer.

In addition to the above components, a conventionally used foaming agent may be used in combination with the hollow fine particles as long as the effects of the present invention are not impaired, and the foaming agent does not react with each of the components during the following mixing step. Sexual gas may be blown. Examples of the foaming agent include water and a foaming agent containing a hydrocarbon having 5 or 6 carbon atoms as a main component. Examples of the hydrocarbon include chain hydrocarbons such as n-pentane and n-hexane, and alicyclic hydrocarbons such as cyclopentane and cyclohexane.

As a method for producing the polishing layer 4 using the urethane bond-containing polyisocyanate compound and the curing agent, for example, at least a preparatory step for preparing the material; at least a mixing step for obtaining a mixed solution of the materials; Examples thereof include a manufacturing method including a molding body molding step of molding a body; and a polishing layer forming step of forming a polishing layer having a polishing surface for polishing an object to be polished from the polyurethane resin molded body. These steps are substantially the same as the method for manufacturing the end point detection window, except that the additive is not mixed and bubbles are formed by adding microhollow spheres or mechanically foaming. Is omitted.

<Manufacturing method of polishing layer equipped with end point detection window>
The polishing layer 4 included in the polishing pad 3 of the present invention includes at least one end point detection window 5. The polishing layer 4 provided with the end point detection window 5 will be described.
As shown in FIG. 7, first, a columnar end point detection window 5 is manufactured. As this manufacturing method, the material may be extruded or may be formed into a columnar shape by grinding or the like. The side surface of the end point detection window 5 may be provided with irregularities or a thread cutting structure, if necessary, in order to facilitate fitting with the polishing layer 4.
Next, the urethane prepolymer, which is the material of the polishing layer 4, the curing agent, and the hollow fine particles are supplied into the mixer and stirred and mixed. With the columnar end point detection window 5 provided, the material of the polishing layer 4 is cured around the columnar end point detection window 5, and a block-shaped polishing layer 4 provided with the columnar end point detection window 5 is formed.
Finally, the polishing layer 4 can be cut out so as to have a desired shape of the polishing pad 3, and the polishing layer 4 can be formed into a polishing layer 4 having a predetermined shape.
The polishing layer 4 provided with the end point detection window 5 can be formed as described above, but is not limited thereto.

The polishing layer 4 thus obtained is then attached with a double-sided tape on the surface of the polishing layer 4 opposite to the polishing surface. The double-sided tape is not particularly limited, and can be arbitrarily selected and used from the double-sided tapes known in the art.

Further, the polishing pad 3 of the present invention may have a single-layer structure composed of only the polishing layer 4, and another layer (lower layer, support layer, FIG. 3, FIG. In No. 7, the cushion layer 6) may be bonded to a plurality of layers. When it has a multi-layer structure, the plurality of layers may be bonded and fixed to each other by using double-sided tape, an adhesive, or the like while applying pressure as necessary. The double-sided tape and adhesive used at this time are not particularly limited, and can be arbitrarily selected from the double-sided tapes and adhesives known in the art. The cushion layer 6 is provided with a through hole 6a in advance at a position corresponding to the end point detection window 5.

Further, in the polishing pad 3 of the present invention, if necessary, the front surface and / or the back surface of the polishing layer 4 and the end point detection window 5 may be ground, and the surface may be grooved or embossed. The method of grinding is not particularly limited, and grinding can be performed by a known method. Specifically, grinding with sandpaper can be mentioned. The shape of the grooving is not particularly limited, and examples thereof include a grid type, a concentric type, and a radial type.

When the polishing pad 3 of the present invention is used, the polishing pad 3 is attached to the polishing surface plate 10 of the polishing machine 1 so that the polishing surface of the polishing layer 4 faces the object to be polished. Then, while supplying the slurry, the polishing surface plate is rotated to polish the processed surface of the object to be polished.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples.

In each of the Examples and Comparative Examples, "parts" shall mean "parts by mass" unless otherwise specified.

The NCO equivalent is "(mass of polyisocyanate compound (parts) + mass of polyol compound (parts)) / [(number of functional groups per molecule of polyisocyanate compound x mass of polyisocyanate compound (parts) / polyisocyanate". Molecular weight of compound)-(Number of functional groups per molecule of polyol compound x mass (parts) of polyol compound / molecular weight of polyol compound)] ”is a numerical value indicating the molecular weight of prepolymer (PP) per NCO group. is there.

<Example 1>
2,4-Toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI) and poly (oxytetramethylene) glycol (PTMG) having a number average molecular weight of 650) are reacted. 100 parts of the isocyanate group-terminated urethane prepolymer having an NCO equivalent of 504 was charged into the first liquid tank and kept warm. Next, separately from the first liquid, 2 parts of sodium polyacrylate was added and mixed with 20 parts of MOCA as a curing agent to obtain a mixed liquid. The obtained mixed liquid was kept warm in the second liquid tank. The liquids of the first liquid tank and the second liquid tank were injected into a mixer provided with two injection ports from the respective injection ports. After injecting the injected two liquids into the mold of the preheated molding machine while mixing and stirring, the mold was tightened, and the mixture was heated for 30 minutes for primary curing. After the primary-cured molded product was removed from the mold, it was secondarily cured in an oven at 130 ° C. for 2 hours to obtain a urethane resin molded product used as an end point detection window. The obtained end point detection window had a D hardness of 45 in a dry state and a D hardness of 36 in an infiltrated state. The degree of swelling was 110%.
On the other hand, an isocyanate group-terminated urethane prepolymer having an NCO equivalent of 460 obtained by reacting 2,4-tolylene diisocyanate (2,4-TDI), a number average molecular weight of 650 poly (oxytetramethylene) glycol (PTMG) and diethylene glycol (DEG). 2. Expanded hollow fine particles having a shell portion of 100 parts of a polymer composed of an acrylonitrile-vinylidene chloride copolymer and an isocyanate gas contained in the shell having a size of 15 to 25 μm (average particle size: 20 μm). Eight parts were added and mixed, charged in the first liquid tank, and kept warm. Next, separately from the first liquid, 25.5 parts of MOCA and 8.5 parts of polypropylene glycol (PPG) were added and mixed as a curing agent, and the temperature was kept in the second liquid tank. The liquids of the first liquid tank and the second liquid tank were injected into a mixer provided with two injection ports from the respective injection ports. The end point detection window was installed in the mold, and the injected two liquids were injected into the mold of the preheated molding machine while mixing and stirring, then the mold was tightened, and the mixture was heated for 30 minutes for primary curing. The primary-cured molded product was demolded and then secondarily cured in an oven at 130 ° C. for 2 hours to obtain a urethane resin molded product. The obtained urethane resin molded product was allowed to cool to 25 ° C., then heated again in an oven at 120 ° C. for 5 hours, and then sliced to a thickness of 1.3 mm to obtain a polishing layer. The obtained polishing layers were stacked in four layers and the D hardness was measured, and the D hardness was 53.
Further, a double-sided tape was attached to the surface of the polishing layer opposite to the polishing surface and attached to the cushion layer to obtain a polishing pad. In the obtained polishing pad, the difference in wear rate between the end point detection window and the polishing layer was 5 to 30.

When the test sample was polished using the obtained end point detection window and the polishing pad composed of the obtained polishing layer, no scratches were generated and no polishing debris or slurry was accumulated near the end point detection window. It was confirmed that.

Description of Code 1 Polishing device 2 Incident light 2a, 2b Reflected light 3 Polishing pad 4, 41, 42 Polishing layer 4a, 41a, 42a Surface of polishing layer 5, 51, 52 End point detection window 5a. 51a, 52a Surface of end point detection window 6 Cushion layer 7 Adhesive layer 8 Polished object 9 Slurry 10 Polishing surface plate 11 Base 12 Thin film 13 Light source 14 Optical sensor 15 Abrasive grains, polishing scrap 16 Holding surface plate

Claims (3)

A polishing pad having a polishing layer partially provided with an end point detection window, wherein the end point detection window is made of a material whose volume expands when infiltrated. The polishing pad according to claim 1, wherein the D hardness of the material of the end point detection window in a wet state is lower than the D hardness in a dry state. The polishing pad according to claim 1 or 2, wherein the end point detection window is polyurethane, polyurea or polyurethane polyurea containing sodium polyacrylate as an additive.

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