JP6111793B2 - Soft polishing pad and method for manufacturing soft polishing pad - Google Patents

Description

  The present invention relates to a soft polishing pad and a method for manufacturing a soft polishing pad, and more particularly to a soft polishing pad manufactured using a wet film forming method and a method for manufacturing the same.

  Conventionally, a chemical mechanical polishing method (CMP method) has been used as a method for polishing and flattening the surface of an object to be polished such as a semiconductor wafer, a glass substrate for a liquid crystal display, a glass substrate for a photomask, or a glass substrate for a magnetic disk. Is used. When polishing an object to be polished using the CMP method, set the object to be polished on the polishing surface of the polishing pad, press the holding surface plate above the object to be polished and apply a predetermined pressure to the object to be polished. Press against the polishing surface of the polishing pad. During polishing, a polishing slurry is supplied between the polishing pad and the object to be polished, and the polishing pad and the object to be polished are rotated while applying a polishing pressure to the object to be polished by the holding surface plate. When the polishing is completed, the rotation of the polishing pad and the object to be polished is stopped, the polishing pressure by the holding surface plate is released, and the object to be polished is removed from the polishing pad.

  In recent years, the polishing slurry is evenly and sufficiently spread over the surface of the object to be polished, and the object to be polished is flattened uniformly and with high accuracy, the consumption of expensive polishing slurry is suppressed, and the cause of scratching In order to achieve efficient discharge of the polishing debris, a technique for forming slurry grooves of various shapes on the polishing surface of the polishing pad is frequently used.

  And what was described in patent document 1 is known as a polishing pad by which the slurry groove | channel was formed in the surface.

Japanese Patent No. 4920965

  However, when a polishing pad with a slurry groove is used, the polishing remaining on the polishing surface portion between the slurry grooves after the polishing pad and the workpiece are stopped until the polishing pressure is released There is a problem that the slurry erodes the object to be polished, and as a result, the shape of the slurry groove (or the shape of the polished surface portion) is transferred to the object to be polished. That is, when the rotation of the polishing pad and the object to be polished is stopped, the polishing pressure applied to the polishing pad and the object to be polished is not released yet, so the object to be polished is in contact with the polishing pad, that is, the slurry. It will be in the state pressed against the grinding | polishing surface part between groove | channels. When the rotation of the polishing pad and the object to be polished is stopped, the polishing slurry remains on the upper part of the polishing surface portion. Therefore, the rotation of the polishing pad and the object to be polished is stopped until the polishing pressure is released. In the meantime, the polishing slurry erodes the object to be polished. In this phenomenon, the contact portion between the object to be polished and the polishing pad is limited to the polishing surface portion of the polishing pad, and the area of the polishing surface portion increases as the proportion of the area of the slurry groove when the polishing pad is viewed from above is increased. As a result, the pressure per unit area applied to the object to be polished from the polishing surface portion to which the polishing slurry is adhered increases, and the pressure for pressing the polishing slurry against the object to be polished increases. It is considered a thing. When the object to be polished is eroded by the polishing slurry, the surface quality of the object to be polished is deteriorated. This problem is particularly noticeable when a highly reactive polishing slurry is used.

  Therefore, the present invention has been made to solve the above-described problems, and the polishing slurry erodes the object to be polished after the rotation of the object to be polished and the polishing pad is stopped until the polishing pressure is released. Then, it aims at providing the polishing pad which can prevent that the shape of a slurry groove | channel is transcribe | transferred to a to-be-polished object, and its manufacturing method.

  In order to solve the above-described problems, the present invention provides a soft polishing pad having a polyurethane polyurethane polishing layer, which is manufactured using a wet film formation method and has teardrop-shaped bubbles formed therein. A plurality of grooves formed on the side opposite to the polishing surface of the layer and a support portion formed between adjacent grooves, and an adjacent support portion between the bottom of the groove and the polishing surface A cross-linking portion is formed, and the cross-linking portion is characterized in that it has a thickness that curves to the surface opposite to the polishing surface due to the hydraulic pressure when the polishing slurry flows.

  According to this invention comprised in this way, the polishing pad which has a bridge | crosslinking part formed between adjacent support parts can be provided. Then, by setting the thickness of the bridging portion to such a thickness that it is curved to the side opposite to the polishing surface by the hydraulic pressure when the polishing slurry flows, the bridging portion is only polished when the polishing slurry is flowing. It is possible to form a groove for flowing the slurry on the polishing surface side of the bridging portion by curving to the opposite surface side. When the polishing slurry is not flowing, that is, when the rotation of the polishing pad is stopped, the crosslinked portion returns to the original flat shape by the restoring force of the polyurethane foam, and the slurry groove on the polishing surface side of the crosslinked portion is substantially Disappear. That is, according to the present invention, by utilizing the compression characteristics of a soft polishing pad made of polyurethane foam and its restoring force, the polishing surface is only applied while the hydraulic pressure when the polishing slurry flows is applied to the polishing surface side of the bridge portion. A groove for flowing the polishing slurry can be formed. Then, when the rotation of the polishing pad and the object to be polished is stopped and the flow of the polishing slurry is stopped, the slurry groove substantially disappears from the polishing surface, so that the slurry after the rotation of the polishing pad and the object to be polished is stopped. It is possible to prevent the shape of the groove from being transferred to the object to be polished. Further, when the slurry groove is substantially eliminated from the polishing surface, the contact area between the object to be polished and the polishing surface is increased compared to that during polishing. Accordingly, the pressure per unit area applied to the object to be polished from the polishing surface, and hence the force with which the polishing slurry is pressed against the object to be polished, can be reduced as compared with polishing, thereby suppressing the erosion of the object to be polished by the polishing slurry. can do.

  In the present invention, the compressibility of the polishing layer is preferably 5 to 20%. If the compression ratio is less than 5%, the bridging portion cannot be sufficiently bent, so that the polishing waste is not discharged smoothly, and as a result, scratches are likely to occur. On the other hand, when the compressibility is higher than 20%, the wear is likely to be too soft and the cross-linked portion tends to disappear.

  In the present invention, it is preferable that the teardrop-shaped bubbles are not opened in the groove.

  According to the present invention configured as described above, it is possible to suppress the polishing slurry that has entered the teardrop-shaped bubbles from the polishing surface side from flowing to the surface opposite to the polishing surface. Thereby, it can suppress that adhesive force, such as an adhesive agent for affixing a polishing pad to a polishing surface plate, falls by polishing slurry.

  Preferably, in the present invention, the method for producing a polishing pad described above, the step of applying a polyurethane resin solution dissolved in a DMF solution on a film-forming substrate having a plurality of protrusions formed on the upper surface; The film forming substrate coated with the polyurethane resin solution is immersed in water to solidify the polyurethane resin solution, and the solidified polyurethane resin is separated from the film forming substrate. .

  As described above, according to the present invention, it is possible to prevent the shape of the slurry groove from being transferred to the object to be polished after the rotation of the object to be polished and the polishing pad is stopped until the polishing pressure is released. In addition, erosion of the object to be polished by the polishing slurry can be suppressed.

1 is a cross-sectional view showing a single-side polishing apparatus to which a polishing pad according to an embodiment of the present invention is applied. 1 is a vertical sectional view of a polishing pad according to an embodiment of the present invention. 1 is a vertical sectional view of a polishing pad according to an embodiment of the present invention.

  Hereinafter, a soft polishing pad and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a single-side polishing apparatus to which a polishing pad according to an embodiment of the present invention is applied.

  First, as shown in FIG. 1, a single-side polishing apparatus 1 flattens a surface of an object to be polished 3 by a CMP method. The single-side polishing apparatus 1 includes a polishing surface plate 5 that rotates about a rotation axis, a polishing pad 7 that is fixed to the upper surface of the polishing surface plate 5, a dresser 11 that sets the polishing surface 9 of the polishing pad 7, and a coated surface. A holding surface plate 13 for holding the polished article 3 and a polishing slurry supply device 15 for supplying polishing slurry to the polishing surface 9 are provided.

  The polishing surface plate 5 has a disk shape, and a shaft is attached to the bottom surface thereof. The single-side polishing apparatus 1 rotates the polishing surface plate 5 by rotating the shaft around its axis. The polishing pad 7 has substantially the same diameter as the polishing surface plate 5 and is attached to the upper surface of the polishing surface plate 5 using an adhesive or a double-sided tape.

  The holding surface plate 13 has, for example, a disk shape corresponding to the object to be polished 3, and when the object to be polished 3 is polished, a predetermined polishing pressure is applied to the object to be polished 3. Is pressed against the polishing surface of the polishing pad 7. The holding surface plate 13 has a diameter approximately half that of the polishing pad 7 and is held so as to be positioned between the rotating shaft of the polishing pad 7 and the outer periphery.

  Such a single-side polishing apparatus 1 rotates the polishing surface plate 5 and the holding surface plate 13 while rotating the polishing surface plate 5 and the holding surface plate 13 while supplying the polishing slurry to the approximate center of the polishing surface 9 of the polishing pad 7 from the polishing slurry supply device 15. The surface of the workpiece 3 held on the board 13 is flattened.

  Next, the polishing pad 7 according to the embodiment of the present invention will be described in detail.

  The polishing pad 7 is a soft polishing pad in which the polishing layer is made of polyurethane foam and a polishing pad base material (not shown) is bonded to the opposite side of the polishing surface of the polishing layer, and is often used for finish polishing. The The thickness of the polishing layer of the polishing pad 7 is preferably about 0.3 to 2.1 mm.

  FIG. 2 is a vertical sectional view of the polishing pad. As shown in FIG. 2, the upper surface of the polishing pad 7 constitutes a polishing surface 9 for polishing the workpiece 3. The polishing surface 9 of the polishing pad 7 forms a flat surface except during polishing, but at the time of polishing, a slurry groove for flowing the polishing slurry is formed by the hydraulic pressure of the polishing slurry, as will be described later. .

  Further, a polishing pad base material (not shown) is disposed on the surface 19 opposite to the polishing surface 9 of the polishing pad 7, and this polishing pad base material is an upper surface of the polishing surface plate 5 using an adhesive or a double-sided tape. Is pasted. A plurality of grooves 21 are formed on the opposite surface 19 of the polishing pad 7. The grooves 21 are formed, for example, in a lattice shape, a continuous shape, or a radial shape. In FIG. 2, the cross section of the groove 21 is rectangular, but the shape of the groove is not limited to this, and a triangular cross section or a semicircular cross section may be used.

  A bridging portion 25 is formed between the bottom 23 of the groove 21 and the polishing surface 9. The bridging portion 25 connects support portions 27 formed between adjacent grooves 21. A large number of tear bubbles 29 are formed in the support portion 27 and the bridging portion 25. The tear bubble 29 extends so as to hang from the polishing surface 9 toward the opposite surface 19. The tear bubble 29 in the polishing pad 7 is included in the polishing pad 7 and does not open outside the polishing pad 7. Therefore, the tear bubble 29 is not opened in the groove 21. For this reason, even if the polishing surface 9 side of the polishing pad 7 is opened by the sharpening process, the polishing slurry can be held in the tear bubble 29 at the time of polishing, and as a result, the polishing pad is attached to the polishing surface plate. It does not act on the adhesive between the adhesive or the polishing layer and the substrate to reduce the adhesive strength of the adhesive. Note that the tear-shaped bubble 29 does not open in the groove 21 means that the opening of the tear-shaped bubble 29 is substantially exposed when the inside of the groove 21 is observed at a magnification of 100 using an electron microscope. Means not.

  The depth of the groove 21 and the thickness of the bridging portion 25 can be adjusted as appropriate so that the compressibility of the polishing layer of the polishing pad 7 belongs to 5 to 20%. You may change the thickness of the bridge | crosslinking part 25 according to the distance from the center of the polishing pad 7 so that it may belong to the range of this compression rate. In this case, it is preferable that the thickness of the bridging portion 25 is reduced near the center of the polishing pad 7 and increased near the periphery. Thus, the bridging portion 25 is easily deformed near the center of the polishing pad 7 where the action of the centrifugal force is weak and the polishing slurry has a low hydraulic pressure, while the polishing pad 7 has a strong action of centrifugal force and a high hydraulic pressure of the polishing slurry. It is possible to make it difficult for the bridging portion 25 to be deformed in the vicinity of the periphery. By changing the thickness of the bridging portion 25 in this way, the amount of the polishing slurry can be made more uniform over the entire polishing surface 9. Moreover, it is preferable that the depth of the groove | channel 21 is about 0.1-0.8 mm, and it is preferable that the thickness of the bridge | crosslinking part 25 is about 0.2-1.3 mm.

  The groove 21 and the bridging portion 25 are formed by using a mold having a shape complementary to the groove 21 when the polishing pad 7 is manufactured using the wet film forming method.

  Specifically, in the wet film forming method, first, a polyurethane resin is dissolved in a DMF solution and applied onto a predetermined film forming substrate. Since this film-forming substrate has a complementary relationship with the shape of the opposite surface of the polishing pad to be finally produced, in order to form the groove 21, it is complementary to the groove 21 on the upper surface. A film-forming substrate on which convex portions having a shape are formed is used as a mold. Then, the resin is solidified and regenerated in water by sinking the film-forming substrate coated with the polyurethane resin solution in a water tank. When the film-forming substrate is submerged in a water tank, a skin layer having a thickness of several μm is formed on the surface of the resin solution in which the resin is in contact with water. Thereafter, the polyurethane resin coagulates and regenerates into a sheet shape on one side of the film-forming substrate by the progress of substitution between the DMF in the polyurethane resin solution and the coagulating liquid. When DMF is desolvated from the polyurethane resin solution and DMF and the coagulating liquid are replaced, foam is formed inside the skin layer (in the polyurethane resin). At this time, since the PET film of the film forming substrate does not allow water to permeate, desolvation occurs on the surface side (skin layer side) of the polyurethane resin solution, and a larger foam is formed on the film forming substrate side than the surface side. , It becomes a teardrop shape that hangs down in the thickness direction from the skin layer. The size of the foaming depends on the speed of the solvent removal, and the foaming of the support portion 27, which takes time to remove the solvent, is larger than that of the bridging portion 25. Then, after the polyurethane resin is completely solidified, the solidified product is peeled off from the film-forming substrate. By such a manufacturing process, a polishing pad having a skin layer on the upper surface, a groove having a shape complementary to the convex portion of the film-forming substrate on the opposite surface, and further having tear-shaped bubbles inside is manufactured. can do.

  Next, the operation of the polishing pad 7 according to the embodiment of the present invention will be described in detail.

  When the workpiece 3 is polished using the polishing pad 7, first, the workpiece 3 is placed on the polishing pad 7, and a predetermined polishing pressure is applied to the workpiece 3 using the holding surface plate 13. At this time, the force with which the object 3 is pressed against the polishing pad 7 is uniform over the entire surface to be polished of the object 3, and the polishing surface of the polishing pad 7 remains flat. Then, the polishing slurry is supplied to the vicinity of the center of the polishing pad 7 by the polishing slurry supply device 15 while rotating the polishing surface plate 5 and the holding surface plate 13 around the central axis thereof. When the polishing slurry is supplied onto the rotating polishing pad 7, the polishing slurry flows in the radial direction of the polishing pad 7 by centrifugal force. When the polishing slurry enters between the polishing pad 7 and the object to be polished 3, the pressure therebetween increases. Since the polishing pad 7 is a soft one having a compressibility of 5 to 20%, when the pressure between the polishing pad 7 and the workpiece 3 increases, the polishing surface 9 of the softer polishing pad 7 is deformed. . The deformation of the polishing surface 9 occurs particularly greatly at a position corresponding to the relatively thin bridging portion 25 than at a position corresponding to the thick support portion 27.

  FIG. 3 is a vertical sectional view of the polishing pad during polishing. As shown in FIG. 3, at the time of polishing, the bridging portion 25 bends toward the opposite surface 19 due to the hydraulic pressure of the polishing slurry that has entered between the polishing pad 7 and the workpiece 3. When the bridging portion 25 is bent, a space is formed between the bridging portion 25 and the workpiece 3 on the polishing surface 9 side. The shape of the space when the polishing pad 7 is viewed from above is a projection of the groove 21 formed on the opposite surface 19 of the polishing pad 7. A space formed between the workpiece 3 and the bridging portion 25 functions as a slurry groove for flowing polishing slurry. When the polishing of the workpiece 3 is finished and the polishing apparatus 1 is stopped, the rotation of the polishing surface plate 5 and the holding surface plate 13 is first stopped and the polishing slurry supply device 15 is also stopped. When the polishing platen 5 is stopped, centrifugal force does not act on the polishing slurry, so that the flow of the polishing slurry stops. If it does so, the hydraulic pressure which acts on the polishing pad 7 from the polishing slurry between the to-be-polished object 3 and the polishing pad 7 will fall, and the shape of the polishing pad 7 will be restored to the original flat shape. Thereby, after the rotation of the polishing surface plate 5 is stopped, since the slurry groove does not substantially exist, it is possible to prevent the shape from being transferred to the workpiece 3. Further, when the rotation of the polishing surface plate 5 and the holding surface plate 13 is stopped, the polishing slurry between the object to be polished 3 and the polishing pad 7 is polished from between the object to be polished 3 and the polishing pad 7. The object 3 is extruded in the radial direction. At this time, all of the polishing slurry between the object to be polished 3 and the polishing pad 7 is not pushed out, and a part of the polishing slurry remains, but in a state where centrifugal force is not acting on the polishing slurry, the polishing surface 9 of the polishing pad 7 is applied. Since the slurry groove does not substantially exist, the remaining polishing slurry does not remain partially biased and spreads uniformly between the workpiece 3 and the polishing pad 7. In the state where the slurry groove is not substantially present on the polishing surface 9 of the polishing pad 7, the entire surface to be polished of the workpiece 3 is in contact with the polishing surface 9. The pressure per unit area between the objects 3 is lower than that in the case where slurry grooves are present on the polishing surface. Therefore, in this state, the object to be polished is hardly eroded by the polishing slurry, and the flatness of the object to be polished can be maintained.

  As described above, according to the polishing pad according to the embodiment of the present invention, the slurry groove can be temporarily formed on the polishing surface 9 only during polishing while the polishing pad 7 is rotated. After stopping, the slurry groove can be removed. Thereby, after the rotation of the polishing pad 7 is stopped, the shape of the slurry groove can be prevented from being transferred to the object to be polished 3. Further, after the rotation of the polishing pad 7 is stopped, the polishing surface 9 of the polishing pad 7 has substantially no slurry groove, so that the force with which the polishing slurry is pressed against the workpiece 3 can be dispersed. . As a result, the pressure per unit area applied to the object to be polished 3 can be reduced, so that the polishing slurry is strongly pressed against the object to be polished and the object to be polished can be prevented from being eroded by the polishing slurry. .

Next, examples of the present invention will be described.
Example 1
In Example 1, 50 parts of a solution containing 15 parts of a polyether polyurethane resin having a 100% modulus of 18.5 MPa and 35 parts of a DMF solution, 24 parts of DMF for viscosity adjustment, and a DMF dispersion containing carbon black as a pigment ( Carbon black, which is a solid content, is contained in an amount of 20% with respect to the total amount.) 19 parts were mixed to prepare a resin solution.

  The modulus is an index representing the hardness of the resin, and the 100% modulus is a value obtained by dividing the load applied when the non-foamed resin sheet is stretched 100% by the unit area. A higher 100% modulus value means a harder resin.

  Next, an uneven PET film was prepared as a substrate for film formation. On the coated surface of the PET film, a lattice pattern was formed in which a plurality of concave portions having a square planar shape were arranged apart from each other. A resin solution was applied to the coating surface of the film forming substrate using a knife coater to obtain a coating film.

  Next, the obtained coating film was immersed in a room temperature coagulation bath made of water as a coagulation bath to coagulate the resin-containing solution, and then washed and dried to obtain a resin sheet having a thickness of 0.9 mm. In the obtained resin sheet, a plurality of substantially square convex portions arranged apart from each other were formed on the surface, and a lattice pattern groove was formed between the plurality of convex portions. The depth of the groove was 0.6 mm, the width was 2.0 mm, the interval was 13 mm, and the bridge portion thickness was 0.3 mm.

  Subsequently, the surface of the resin sheet on which the irregularities were formed was attached to a PET film (thickness: 188 μm) as a polishing pad substrate through a double-sided tape to obtain a polishing pad.

(Example 2)
A polishing pad was obtained in the same manner as in Example 1 except that the 100% modulus was changed to 11.8 MPa.

(Example 3)
A polishing pad was obtained in the same manner as in Example 1 except that the 100% modulus was changed to 8.5 MPa.

(Comparative Example 1)
A polishing pad was obtained in the same manner as in Example 1 except that the 100% modulus was changed to 23 MPa.

(Comparative Example 2)
In Comparative Example 2, as a prepolymer of the first component, 385 parts of 2,4-TDI, 385 parts of hydrogenated MDI, and 1000 parts of PTMG having a number average molecular weight of about 2000 were reacted with a terminal isocyanate having an isocyanate content of 15.4%. Using a group-containing urethane prepolymer, this was heated to 80 ° C. and degassed under reduced pressure. As the second component, 100 parts of MOCA, 100 parts of PTMG having a number average molecular weight of about 1000, 2 parts of catalyst (Toyocat ET, manufactured by Tosoh Corporation), silicon surfactant (SH-193, Dow) 2 parts of Corning) were added and stirred and mixed at 50 ° C., and then degassed under reduced pressure.

  And the obtained 1st component and 2nd component were supplied to the mixing tank in the ratio of 100 parts: 61 parts by weight ratio. In the mixing step, the stirring conditions were set to a shear rate of 1689 times and a shear rate of 9425 / second. At this time, air was supplied into the mixing tank at a flow rate of 30 L / min. After the obtained mixed liquid was poured into a mold and cured, the formed polyurethane foam was extracted from the mold. This foam was sliced to a thickness of 0.9 mm to produce a urethane sheet, and a polishing pad was obtained. A grid-like groove (depth: 0.6 mm, width: 2.0 mm, interval: 13 mm) was formed by a groove processing machine on the surface of the obtained polishing pad to be bonded to the polishing surface plate.

(Comparative Example 3)
After preparing a resin solution in the same manner as in Example 2, the resin solution was applied onto a flat film-forming substrate to obtain a coating film. Subsequently, the obtained coating film was immersed in a room temperature coagulation bath made of water as a coagulation bath to coagulate the resin-containing solution, and then washed and dried to obtain a resin sheet having a thickness of 0.9 mm. Subsequently, a surface opposite to the skin layer of the resin sheet and a PET film (thickness: 188 μm) as a substrate for film formation were bonded together through a double-sided tape to obtain a polishing pad. A lattice groove (depth: 0.6 mm, width: 2.0 mm, interval: 13 mm) was formed on the skin layer side of the obtained polyurethane sheet with a groove processing machine.

  The polishing pads obtained in Examples 1 to 3 and Comparative Examples 1 to 3 described above were subjected to physical property evaluation and polishing tests under the following conditions.

(Evaluation of the physical properties)
The compression rate was determined according to Japanese Industrial Standard (JIS L 1021) using a shopper type thickness measuring instrument (pressurized surface: circular shape with a diameter of 1 cm). Specific measurement conditions are as follows.

The thickness t ₀ after applying the initial load for 30 seconds from the unloaded state was measured, and then the thickness t ₁ after applying the final pressure from the state of thickness t ₀ for 300 seconds was measured. The compressibility was calculated by the formula of compressibility (%) = 100 × (t ₀ −t ₁ ) / t ₀ (note that the initial load was 100 g / cm ² and the final pressure was 1120 g / cm ² ). The measurement was performed at five locations excluding the cross-linked portion, and the average value was taken as the compression rate of the product of the present invention.

(Polishing test)
The obtained polishing pad was placed at a predetermined position of a polishing machine (trade name “9B-5P polishing machine” manufactured by Speed Fam Co., Ltd.), and polishing was performed using an aluminum substrate for 95 mmφ hard disk as an object to be polished. The polishing conditions at this time are a polishing rate (rotation number) of 30 rpm, a polishing pressure of 100 g / cm ² , a polishing agent using colloidal silica slurry (pH: 1.5), a polishing agent discharge rate of 100 cc / min, and a polishing time of 300. Seconds.

(Presence / absence of transcription)
After the polishing was completed, the polishing platen was stopped rotating for 1 minute with a polishing pressure of 100 g / cm ² applied. Thereafter, the presence or absence of transfer onto the surface of the workpiece was examined visually.

(scratch)
The occurrence of scratches was confirmed by observing the surface of the polished aluminum substrate with a microscope. The case where 0 to 4 scratches were confirmed was evaluated as “◯”, the case where 5 to 9 scratches were confirmed and “△” as the other scratches, and the case where 10 or more scratches were confirmed as “X”.

(result)
Table 1 shows the results of the test described above.

  As can be seen from Table 1, when the polishing pad of Comparative Example 1 was used, more scratches were generated than when the polishing pad according to Examples 1 to 3 was used. This is considered to be because the polishing pad according to Comparative Example 1 has a low compressibility and the bridging portion cannot be sufficiently bent, and the polishing waste is not discharged smoothly. In addition, since the groove | channel was not formed in the grinding | polishing surface, the polishing pad of the comparative example 1 did not produce transfer to to-be-polished material.

  Further, when the polishing pad according to Examples 1 to 3 was used, the amount of scratches was small because the compression rate was appropriate, and there was no problem with the quality of the polishing pad. Further, since the polishing pad according to Examples 1 to 3 had a flat polishing surface, no transfer occurred on the object to be polished.

  In addition, the polishing pad of Comparative Example 2 has a low compression ratio and the bridging portion cannot be sufficiently bent as in the polishing pad of Comparative Example 1, and polishing scraps are not discharged smoothly, so that there are many scratches. It was. Moreover, since the groove | channel was not formed in the polishing surface also in the polishing pad of the comparative example 2, transcription | transfer did not arise in the to-be-polished object.

  Moreover, since the compression rate of the polishing pad of Comparative Example 3 was appropriate, the amount of scratches was small, and there was no problem with the quality of the polishing pad. However, transfer occurred because of the grooves formed on the polished surface.

DESCRIPTION OF SYMBOLS 1 Polishing apparatus 3 To-be-polished object 7 Polishing pad 9 Polishing surface 19 The opposite surface 21 of a polishing pad 21 Groove 23 Groove bottom 25 Bridging part 27 Support part 29 Tear-shaped bubble

Claims (4)

A soft polishing pad having a polishing layer made of polyurethane foam, which is manufactured using a wet film formation method and in which teardrop-shaped bubbles are formed,
A plurality of grooves formed on the surface opposite to the polishing surface of the polishing layer and a support portion formed between adjacent grooves;
Between the bottom of the groove and the polishing surface, a bridging portion that connects adjacent support portions is formed, and this bridging portion is opposite to the polishing surface due to the hydraulic pressure when the polishing slurry flows. A soft polishing pad characterized by having a thickness that is curved in a straight line. The soft polishing pad according to claim 1, wherein the polishing layer has a compressibility of 5 to 20%.   The soft polishing pad according to claim 1, wherein the teardrop-shaped bubbles are not opened in the groove. A method for producing a soft polishing pad according to claim 1,
Applying a polyurethane resin solution dissolved in a DMF solution on a film-forming substrate having a plurality of convex portions formed on the upper surface;
Immersing the film-forming substrate coated with the polyurethane resin solution in water to solidify the polyurethane resin solution; and
And a step of peeling the solidified polyurethane resin from the film-forming substrate.

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