JP6446337B2 - Polishing pad - Google Patents

Description

  The present invention relates to a polishing pad useful for polishing semiconductor wafers, silicon wafers, semiconductor devices, liquid crystal displays, hard disks, glass lenses, metals and the like.

  Chemical mechanical polishing (CMP) is known as mirror processing of a semiconductor wafer used as a base material for forming an integrated circuit. Polishing pads used in CMP include non-woven fabric type sheets impregnated with wet-coagulated polyurethane on non-woven fabrics, and wet PU sponges with wet-coagulated polyurethane resin on the top layer of films and fiber structures. Type sheets and molded sheets of polymer elastic bodies such as polyurethane having a closed cell structure are used. Nonwoven fabric type sheets and wet PU sponge types are relatively soft because they are easily compressed and deformed, while a molded sheet of a polymer elastic body has high rigidity.

In recent years, with higher integration and multilayer wiring, demands for quality improvement such as higher planarization and lower prices are increasing for semiconductor wafers and semiconductor devices. Attempts have been made to use a copper alloy as the wiring material instead of the conventional aluminum alloy, and a low dielectric constant material as the insulating material instead of the conventional SiO ₂ . Along with such material changes, it is possible to flatten the polishing pad even more than before, reduce the scratch on the wafer surface, increase the polishing rate, improve the stability in polishing, and use for a long time There is a demand for higher functionality such as being possible. Also, silicon wafers, liquid crystal displays, hard disks, glass lenses, etc. are being highly integrated and highly accurate, so that even polishing pads can be made flatter than before, and surface scratches can be made. There is a demand for further enhancement of functionality, such as reducing the slag, increasing the polishing rate, improving the stability in polishing, and being usable for a long time.

  The foamed polyurethane used for the polishing pad of the foamed polyurethane molded sheet is generally produced by cast foam curing using a two-component curable polyurethane (see, for example, Patent Documents 1 to 4). However, these methods make it difficult to make the reaction and foam uniform, and the hardness of the resulting polyurethane foam is limited. Therefore, the polishing characteristics such as the flatness of the surface to be polished and the flattening efficiency vary. In addition, since the foamed structure is an independent hole, the polishing slurry and polishing debris used in the polishing step are likely to enter the gap and clog, and the polishing rate (polishing rate) decreases, There were problems such as short pad life. For this reason, the required performance as described above (further improvement in planarization efficiency, reduction in scratches on the wafer surface, improvement in polishing rate, stability in polishing and improvement in the life of the polishing pad, etc.) are sufficiently satisfied. A polishing pad of a molded sheet made of polyurethane foam has not been obtained. For this reason, in particular, materials that are easily scratched, such as copper wiring and low dielectric constant materials, and materials that have poor adhesion at the interface, are more likely to cause scratches and interfacial delamination. Development is required.

  On the other hand, a nonwoven fabric type polishing pad generally has a concavo-convex structure due to fibers formed on the surface, or has voids and communication hole structures due to the structure of the nonwoven fabric. Therefore, it has features such as good liquid retention of the slurry during polishing (hereinafter also referred to as slurry retention), easy to increase the polishing rate, good cushioning properties, flexibility and good contact with the wafer. And is used in various fields of polishing. However, conventional non-woven fabric type polishing pads do not have sufficient ability to flatten due to the large number of voids and flexibility, and also have insufficient polishing stability and polishing pad life. For this reason, various studies for higher performance have been made (see, for example, Patent Documents 6 to 14). However, in either case, there are the following problems. (1) Since the fiber diameter is about several tens of μm and the unevenness on the surface of the polishing pad due to the fiber is relatively large with respect to the level difference of the wafer, there is a limit to the improvement in flatness and the abrasive grains in the fiber When the flocculates, it tends to cause scratches. In addition, when ultrafine fibers are used, the sheet made of ultrafine fibers has very soft characteristics, so the hardness is insufficient, or when the hardness is increased using a very hard polymer elastic body, The wafer is easily damaged due to the hardness and brittleness of the molecular elastic body. (2) Since the density of the fiber is low, the number of napped surfaces (density of the uneven structure) due to the fiber is small, and the effect of combining the fiber with the polymer elastic body is not sufficient. (3) Since the density of the sheet is low and there are many voids, it is difficult to obtain a sheet with high hardness, and because there are huge non-woven fabric voids on the order of several 100 μm on the surface, there is a limit to improving the flatness. Furthermore, the performance such as hardness is likely to change with time during polishing, and there is a problem in the stability of polishing and the life of the polishing pad. (4) When the polymer elastic body is completely filled to remove the voids of the nonwoven fabric, the features due to the formation of surface irregularities due to the fibers, the voids of the nonwoven fabric structure and the communicating hole structure are lost.

  For this reason, the performance required by the market (further improvement of planarization efficiency, reduction of scratches on the wafer surface, improvement of the polishing rate, improvement in polishing stability and the life of the polishing pad, etc.) is fully satisfied. A non-woven type polishing pad has not yet been found.

JP 2000-178374 A JP 2000-248034 A JP 2001-89548 A Japanese Patent Laid-Open No. 11-322878 JP 2002-9026 A JP-A-11-99479 Japanese Patent Laying-Open No. 2005-212055 JP-A-3-234475 Japanese Patent Laid-Open No. 10-128797 JP 2004-311731 A Japanese Patent Laid-Open No. 10-225864 JP-T-2005-518286 JP 2003-201676 A JP 2005-334997 A

  The present invention is a non-woven fabric type polishing pad that has a polishing performance that is excellent in polishing stability and smoothness of an object to be polished, and has a feature that a change in polishing performance is small even if polishing is continued for a long time. An object is to provide a polishing pad.

One aspect of the present invention includes a polyester fiber nonwoven fabric and a polymer elastic body impregnated in the nonwoven fabric, the polymer elastic body being a nonporous polymer elastic body and a D hardness of 35 to 80 The mass ratio of the nonwoven fabric of polyester fiber is 0.4 to 0.6, and the mass ratio of the content of the nonporous polymer elastic body to the content of the porous thermoplastic polyurethane is 0. A polishing pad that is .73 to 0.85. Nonporous polymer elastic bodies are mainly used for maintaining shape stability in the production process of nonwoven fabrics. Further, the porous thermoplastic polyurethane having a D hardness of 35 to 80 contributes to improving the retention of the polishing slurry by adjusting the hardness of the polishing pad and imparting fine bubbles to the surface layer. According to such a configuration, in the nonwoven fabric type polishing pad having a polishing performance excellent in polishing stability and smoothness of a polishing object, and having a characteristic that a change in polishing performance is small even if polishing is continued for a long time, A polishing pad with a high polishing rate can be obtained.

  In the polishing pad, it is preferable that the polyester fiber is a polybutylene terephthalate-based hollow fiber having an average single fiber fineness of 1 to 10 dtex because it is easy to split and excellent in low scratch properties.

In the polishing pad, the porous thermoplastic polyurethane contains at least 80% of the pores in the range of the pore cross-sectional area of 11 to 100 μm ² to improve the slurry retention and maintain a high polishing rate. It is preferable because of

  In addition, the porous thermoplastic polyurethane includes a thermoplastic polyurethane obtained by reacting a polymer diol, an organic diisocyanate, and a chain extender, and the polymer diol includes poly (butylene adipate), poly (caprolactone), Poly (ethylene glycol), poly (tetramethylene glycol), poly (nonamethylene adipate), poly (2-methyl-1,8-octamethylene adipate), poly (2-methyl-1,8-octamethylene-co-) Nonamethylene adipate) and poly (methylpentane adipate), and the organic diisocyanate is 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate. , From isophorone diisocyanate The chain extender contains at least one selected from the group, and the chain extender is 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, cyclohexanedimethanol It is preferable to include at least one selected from the group consisting of

In addition, since the apparent density of the polishing pad is 0.35 to 0.50 g / cm ³ , since the rigidity and the volume of the communication hole are appropriate, a high polishing rate can be obtained while suppressing scratches. preferable.

  The polishing pad preferably has a hardness of 60C to 90C.

  ADVANTAGE OF THE INVENTION According to this invention, a polishing pad with a high polishing rate is obtained in a nonwoven fabric type polishing pad.

  Hereinafter, an embodiment of the polishing pad of the present invention will be described in detail.

The polishing pad of the present embodiment includes a nonwoven fabric of polyester fiber and a polymer elastic body impregnated in the nonwoven fabric, and the polymer elastic body is a nonporous polymer elastic body and a D hardness of 35 to 80. Quality thermoplastic polyurethane. And the mass ratio of the nonwoven fabric of a polyester fiber is 0.4-0.6, and mass ratio of content of a nonporous polymeric elastic body with respect to content of porous thermoplastic polyurethane is 0.73-0.00 . 85 is a polishing pad.

  The non-woven fabric of polyester fiber is not particularly limited as long as it is a non-woven fabric of a fiber mainly composed of a polyester resin such as polybutylene terephthalate (PBT) or polyethylene terephthalate (PET). In particular, when the polyester fiber is formed with PBT as a main component, it is difficult to absorb water during polishing, so that the storage elastic modulus E ′ is unlikely to fluctuate and the polishing efficiency is stabilized. For example, in the case of a highly water-absorbing fiber such as nylon fiber, the storage elastic modulus E ′ fluctuates due to a high water absorption rate during polishing, and the polishing pad is easily deformed, resulting in a decrease in polishing efficiency. It becomes easy.

  The fineness of the polyester fiber is preferably an average single fiber fineness of 1 to 10 dtex, more preferably 1.5 to 8.5 dtex. If the average single fiber fineness is too low, it tends to be difficult to separate. Further, when the average single fiber fineness is too high, the load on the object to be polished is increased, and the low scratch property tends to be lowered.

  The cross-sectional shape of the polyester fiber is not particularly limited, but in particular, the polyester fiber is preferably a hollow fiber, that is, a hollow fiber having at least one hole in the cross section of the fiber. By having at least one hole in the cross section, the hollow fibers on the surface of the polishing pad are sufficiently separated, so that the slurry holding power is improved and the polishing efficiency is remarkably improved.

  The polishing pad of the present embodiment includes a nonporous polymer elastic body impregnated with a nonwoven fabric of polyester fibers, and a porous thermoplastic polyurethane having a D hardness of 35 to 80.

  Nonporous polymer elastic bodies are mainly used for maintaining shape stability in the production process of nonwoven fabrics. In addition, the porous thermoplastic polyurethane having D hardness of 35 to 80 improves the retention of the polishing slurry during CMP polishing by adjusting the hardness of the polishing pad and imparting fine bubbles to the surface layer. It contributes to that. The nonporous polymer elastic body can be impregnated by, for example, impregnating a nonwoven fabric with an emulsion of a nonporous polymer elastic body and drying it. The porous thermoplastic polyurethane can be impregnated by impregnating a nonwoven fabric with a solution of thermoplastic polyurethane that forms the porous thermoplastic polyurethane and wet coagulating it.

  Specific examples of the nonporous polymer elastic body include nonporous, for example, polyurethane, acrylonitrile elastomer, olefin elastomer, polyester elastomer, polyamide elastomer, acrylic elastomer, and the like. Of these, polyurethane is preferred.

  The nonporous polyurethane is preferably formed using an aqueous emulsion. Specific examples of the aqueous polyurethane emulsion include polycarbonate-based polyurethane, polyester-based polyurethane, polyether-based polyurethane, and polycarbonate / ether-based polyurethane aqueous emulsion.

  The non-porous polymer elastic body has a glass transition temperature of −10 ° C. or lower, a storage elastic modulus at 23 ° C. and 50 ° C. of 1 to 40 MPa, and further 1 to 35 MPa, and saturated water absorption at 50 ° C. Polyurethanes having a water absorption rate of 0.2 to 5% by mass when they are used are preferred. When the storage elastic modulus at 23 ° C. and 50 ° C. is too low, the polishing pad tends to be easily deformed. In addition, when the storage elastic modulus is too high, it tends to be hard and brittle and easily generate scratches. If the water absorption is too low, the amount of slurry retained during polishing tends to decrease, and the polishing uniformity tends to decrease. If the water absorption is too high, characteristics such as hardness tend to change during polishing and the polishing stability tends to decrease.

  The porous thermoplastic polyurethane is a porous body of thermoplastic polyurethane having a D hardness of 35 to 80, preferably 40 to 80. When the D hardness of the porous thermoplastic polyurethane is 35 to 80, high durability can be maintained and appropriate pad following performance can be maintained. This makes it difficult for the pores formed during polishing to disappear, and as a result, the slurry holding force of the polishing pad is improved and the polishing rate is increased. When the D hardness of the thermoplastic polyurethane is less than 35, the durability decreases, and the formed pores melt and disappear during polishing. As a result, the slurry holding power of the polishing pad is reduced and the polishing rate is lowered. On the other hand, when the D hardness exceeds 80, the storage elastic modulus during polishing becomes too high, the pad following ability is deteriorated, and the polishing rate is lowered.

In the case of porous thermoplastic polyurethane, if the pore cross-sectional area of 11 to 100 μm ² contains 80% or more of pores, and further 85% or more, the slurry holding power can be improved and the polishing rate can be kept high. It is preferable from the point which can be performed. When the ratio of the pores included in the range of the pore cross-sectional area of 11 to 100 μm ² is low, the amount of slurry retained during polishing tends to decrease and the polishing rate tends to decrease, or the polishing uniformity tends to decrease. There is.

  The thermoplastic polyurethane that forms the porous thermoplastic polyurethane (hereinafter also simply referred to as polyurethane) will be described in detail. The method for producing polyurethane is not particularly limited, for example, a method in which a polymer diol, an organic diisocyanate, and a chain extender are melt-mixed at a predetermined ratio and melt-polymerized substantially in the absence of a solvent, or a known urethanization method. A prepolymer method using a reaction or a one-shot method is used. Among these, a melt polymerization method is particularly preferably used from the viewpoint of production efficiency. The melt polymerization is a method in which a high molecular diol, an organic diisocyanate, a chain extender, and an additive that is blended as necessary are blended in a predetermined ratio and are continuously melt polymerized using a multi-screw extruder.

  The polymer diol, organic diisocyanate, and chain extender, which are raw materials for polyurethane polymerization, will be described in detail.

  Specific examples of the polymer diol include, for example, poly (butylene adipate), poly (caprolactone), poly (ethylene glycol), poly (tetramethylene glycol), poly (nonamethylene adipate), poly (2-methyl-1, 8-octamethylene adipate), poly (2-methyl-1,8-octamethylene-co-nonamethylene adipate), at least one selected from the group consisting of poly (methylpentane adipate) and poly (butylene adipate) Poly (caprolactone), poly (ethylene glycol), and poly (tetramethylene glycol) are preferred. Furthermore, poly (caprolactone) is preferable.

  As the organic diisocyanate, any of the organic diisocyanates conventionally used in the production of ordinary thermoplastic polyurethanes may be used. 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6- It is at least one selected from the group consisting of tolylene diisocyanate and isophorone diisocyanate, and two or more may be used in combination. Among these, 4,4'-diphenylmethane diisocyanate is preferable from the viewpoint of wear resistance of the resulting polishing pad.

  As the chain extender, any chain extender conventionally used in the production of ordinary polyurethane may be used. As the chain extender, it is preferable to use a low molecular weight compound having a molecular weight of 300 or less and having 2 or more active hydrogen atoms capable of reacting with an isocyanate group, and 1,3-propanediol, 1,4-butanediol , Neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, cyclohexanedimethanol may be used alone or in combination of two or more. May be.

  In the polishing pad of this embodiment, the mass ratio of the nonwoven fabric of the polyester fiber in a polishing pad is 0.4-0.6, Preferably it is 0.45-0.55. On the other hand, the mass ratio of the polymer elastic body in the polishing pad (the total of the nonporous polymer elastic body and the D hardness of 35 to 80 porous thermoplastic polyurethane) is also 0.6 to 0.4, preferably 0.55 to 0.45. When the mass ratio of the polyester fiber nonwoven fabric in the polishing pad is less than 0.4, the amount of fibers on the polishing surface of the polishing pad is insufficient and the slurry retention is reduced, resulting in a reduction in the polishing rate. Moreover, when the mass ratio of the nonwoven fabric of the polyester fiber in a polishing pad exceeds 0.6, the adhesiveness of fibers will fall and it will become easy to generate | occur | produce a scratch on the pad surface during grinding | polishing.

The polishing pad of this embodiment includes a non-porous polymer elastic body impregnated in a nonwoven fabric and a porous thermoplastic polyurethane having a D hardness of 35 to 80, and is based on the content of the porous thermoplastic polyurethane. the mass ratio of the content of nonporous elastic polymer is from 0.73 to 0.8 5. Porous Shitsunetsu If the mass ratio of the content of nonporous elastic polymer to the content of the thermoplastic polyurethane is 0.73 less than sufficiently retained nonwoven shape impregnation step reduced adhesion between fibers Otherwise, the form stability is lowered and the productivity is lowered. Further, when the mass ratio of the content of the nonporous polymer elastic body to the content of the porous thermoplastic polyurethane exceeds 0.85, the porous thermoplastic polyurethane in the polishing pad is reduced, and the slurry being polished Retention is lowered and the polishing rate is lowered.

The polishing pad of the present embodiment has an apparent density of 0.35 to 0.50 g / cm ³ , further 0.35 to 0.50 g / cm ³ , particularly 0.35 to 0.45 g / cm ^3. Is preferred. When the apparent density is too low, the polishing rate tends to be low due to low rigidity, and when the apparent density is too high, the volume of the communication hole is reduced and the abrasive particles and abrasive slurry are discharged. As a result, the effect of suppressing scratches on the surface to be polished tends to decrease.

  The polishing pad of this embodiment preferably has a pad hardness of 60C to 90C, more preferably 65C to 85C. If the pad hardness is too low, the polishing pad becomes too soft and the polishing rate and planarization performance are reduced. Further, when the pad hardness is too high, it becomes too hard and the followability to the surface to be polished is lowered, so that the polishing rate is lowered and scratches tend to occur on the surface to be polished.

  The polishing pad of this embodiment is impregnated with an elastomer sheet or an elastomer having a foamed structure or a non-foamed structure in order to provide cushioning to the surface opposite to the polished surface, even as a single-layer polishing pad. You may use as a polishing pad of the multilayer structure which laminated | stacked the well-known cushion layer which consists of a nonwoven fabric etc. A cushion layer is laminated | stacked on a sheet | seat using an adhesive or an adhesive agent.

  Although the thickness of the polishing pad is not particularly limited, it is 0.8 to 3.5 mm, further 1.0 to 3.0 mm, particularly 1.2 to 2.5 mm from the viewpoint of polishing performance and pad life. preferable.

  Moreover, it is preferable to form a groove or a hole for holding the aqueous slurry on the polishing surface of the polishing pad by grinding, laser processing, embossing or the like, if necessary.

  The polishing target of the polishing pad is not particularly limited, and examples thereof include a semiconductor substrate such as a silicon wafer, a glass substrate, a semiconductor device, a liquid crystal display, and the like. As the polishing method, a chemical mechanical polishing apparatus (CMP apparatus) and a chemical mechanical polishing method (CMP) using an aqueous slurry are preferably used. As CMP, for example, a polishing pad is affixed to a polishing surface plate of a CMP apparatus, an aqueous slurry is supplied to the polishing surface, and pressure is applied while pressing an object to be polished against the polishing pad. The method of grind | polishing the surface of a to-be-polished object by rotating together is mentioned. In addition, before polishing or during polishing, it is preferable to condition and prepare the polishing surface using a dresser such as a diamond dresser or a nylon brush, if necessary.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

  First, the evaluation methods used in this example will be described together.

[Mass ratio of polyester fiber non-woven fabric, mass ratio of nonporous polymer elastic body]
Based on the weight change in the production process of the polishing pad stock, the weight of the nonwoven fabric of polyester hollow fibers (Wa), the weight of impregnated nonporous polymer elastic body (nonporous polyurethane) (Wb), impregnated The weight (Wc) of the porous thermoplastic polyurethane is obtained. From the equation of Wa / (Wa + Wb + Wc), the mass ratio of the nonwoven fabric of the polyester fiber in the polishing pad, Wb / Wc, the porous thermoplastic polyurethane The mass ratio of the content of the nonporous polymer elastic body to the content was determined.

[Ratio of the range of pore cross-sectional area of 11 to 100 μm ² ]
The cross section of the obtained polishing pad was photographed with a scanning microscope (SEM) at a magnification of 200 times. Then, the pore cross-sectional area of the thermoplastic polyurethane was binarized by image processing from the obtained SEM photograph, and the ratio of the range of the pore cross-sectional area of 11 to 100 μm ² was calculated from the area ratio.

[Hardness measurement]
The hardness was determined by averaging 10 points measured by stacking thermoplastic polyurethane sheets obtained by hot press molding according to JIS K 7311 or polishing pads so as to have a thickness of 6 mm or more.

[Apparent density]
The apparent volume was determined from the width, length and thickness of the original fabric, and the weight was determined by dividing the apparent volume.

[Polishing rate]
The polishing rate of the obtained polishing pad was evaluated by the following method. The obtained polishing pad was set in a CMP polishing apparatus (“MAT-BC15” manufactured by MTT Co., Ltd.). Then, a bare silicon wafer having a diameter of 4 inches was polished for 10 minutes while supplying a polishing slurry at a rate of 200 mL / min under the conditions of a platen rotation speed of 100 rpm, a head rotation speed of 99 rpm, and a polishing pressure of 57 kPa. As the polishing slurry, a slurry prepared by diluting “Glanzox1302” manufactured by Fujimi Incorporated with a factor of 20 was used. Thereafter, the bare silicon wafer was replaced and the polishing was repeated in the same manner, and a total of 10 bare silicon wafers were polished. Then, the polishing rate was calculated from the weight difference between the polished 10 bare silicon wafers before and after polishing. And the average value of the polishing rate of ten bare silicon wafers was calculated.

[Example 1]
[Manufacture of raw fabric containing hollow fiber non-woven fabric and non-porous polyurethane]
A sea-island type composite fiber strand of 12 islands containing polybutylene terephthalate (PBT) as a sea component and water-soluble thermoplastic PVA as an island component and having a mass ratio of sea component / island component of 50/50 is melted at 265 ° C. A sea-island type composite fiber was spun by discharging from a composite spinning nozzle and cooling it while drawing and thinning. And the continuous fiber web was obtained by collecting and pressing continuously. Next, the long fiber webs were overlapped, and needle punching was alternately performed on both sides to entangle the long fiber webs to obtain a three-dimensional entangled body.
Next, as a nonporous polymer elastic body, a polyurethane aqueous emulsion was impregnated by dip-niping into a three-dimensional entangled body and subjected to a drying treatment. Then, both surfaces were buffed with sandpaper and flattened. Next, the three-dimensional entangled body is dip-niped in hot water to dissolve and remove the water-soluble thermoplastic PVA, which is an island component, from the sea-island composite fiber, and then dried to form a PBT having 12 hollow portions in the cross section. A raw fabric containing a nonwoven fabric (thickness 1.5 mm) of hollow fibers (average single fiber fineness of 2.36 dtex) and nonporous polyurethane was obtained.

[Impregnation with porous thermoplastic polyurethane]
The raw fabric containing the obtained hollow fiber nonwoven fabric and nonporous polyurethane was cut into 230 mm × 230 mm. The cut raw material was impregnated with porous thermoplastic polyurethane having a D hardness of 40 (Milactolan E590PNAT manufactured by Tosoh Corporation). Table 1 shows the composition and hardness of the thermoplastic polyurethane.

  Impregnation was performed as follows. A DMF solution of TPU having a thermoplastic polyurethane (TPU) concentration of 13% was prepared. Then, after allowing the original fabric to stand for 15 minutes on the DMF solution heated to 50 ° C. to infiltrate the DMF solution, the substrate is further immersed for 5 minutes, and then the original fabric is taken out and placed on a glass plate, The excess DMF solution was removed by tracing with a doctor knife. The same operation was performed on the back side.

  Then, the porous thermoplastic polyurethane was coagulated by immersing the raw material infiltrated with the DMF solution into a DMF aqueous solution adjusted to a DMF concentration of 40% and adjusted to 30 ° C. and allowing to stand for 30 minutes. And the raw material which solidified and impregnated porous thermoplastic polyurethane was immersed in hot water of 70-95 degreeC, it pinched | interposed with the metal roll, after squeezing out water, it was made to immerse in hot water again, and washes with water did. This operation was repeated until the DMF concentration of the squeezed water was 0.3% or less. The DMF concentration was measured with an Abbe refractometer 1T (Atago Co., Ltd.). And the raw fabric washed with water was put into a hot air dryer (device name: Safety Oven SPH-202 / Espec Corp.) and dried at 100 ° C. for 40 minutes. In this way, a polishing pad original fabric (referred to as a pad original fabric) was obtained.

[Flatening and groove processing of pad stock]
A polishing pad was prepared by buffing the surface of the pad stock with sandpaper (count # 240) to make the surface flat without any unevenness in thickness. Then, the polishing pad was cut out to 210 mm × 210 mm. Then, four of the cut out polishing pads were bonded together to 420 mm × 420 mm, and an adhesive tape was applied to the surface to be polished. Then, a grating groove having a groove width of 2.0 mm, a groove depth of 0.5 mm, and a pitch of 15 mm was formed on the polishing surface of the polishing pad by a flattening groove processing machine. And the polishing pad with a groove | channel which cut out the polishing pad in which the lattice groove | channel was formed in the circular shape of 380 mmphi was obtained. And it evaluated by the above evaluation methods. The results are shown in Table 1.

[Example 2]
In Example 1 [Providing impregnation with porous thermoplastic polyurethane], instead of thermoplastic polyurethane having D hardness of 40 (Milaclan E590PNAT manufactured by Tosoh Corporation), thermoplastic polyurethane having D hardness of 64 (Milaclan manufactured by Tosoh Corporation) A grooved polishing pad was obtained in the same manner except that E564PNAT) was used. And it evaluated by the above evaluation methods. The results are shown in Table 1.

[Example 3]
In Example 1 [Providing impregnation with porous thermoplastic polyurethane], instead of thermoplastic polyurethane having D hardness of 40 (Milactolan E590PNAT manufactured by Tosoh Corp.), thermoplastic polyurethane having D hardness of 74 (Milaclan manufactured by Tosoh Corporation) A grooved polishing pad was obtained in the same manner except that E574PNAT) was used. And it evaluated by the above evaluation methods. The results are shown in Table 1.

[Example 4]
In Example 1 [Providing impregnation of porous thermoplastic polyurethane], instead of thermoplastic polyurethane having D hardness of 40 (Milactolan E590PNAT manufactured by Tosoh Corporation), thermoplastic polyurethane having a D hardness of 80 (Daiichi Seika Co., Ltd.) A grooved polishing pad was obtained in the same manner except for using Rezamin P-1330). And it evaluated by the above evaluation methods. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, [Impregnation with porous thermoplastic polyurethane], instead of thermoplastic polyurethane having D hardness of 40 (Milactolan E590PNAT manufactured by Tosoh Corporation), wet polyurethane having D hardness of 30 (Kuraray Co., Ltd. S) A grooved polishing pad was obtained in the same manner except that -DAU) was used. And it evaluated by the above evaluation methods. The results are shown in Table 1.

[Comparative Example 2]
In Example 1 [Impregnation with porous thermoplastic polyurethane], a thermoplastic polyurethane with a D hardness of 30 (Milactolan E580PNAT) was used instead of a thermoplastic polyurethane with a D hardness of 40 (Milaclan E590PNAT manufactured by Tosoh Corporation). A grooved polishing pad was obtained in the same manner except that. And it evaluated by the above evaluation methods. The results are shown in Table 1.

  From Table 1, the polishing pads of Examples 1 to 4 control the weight ratio of each component of the nonwoven fabric made of polyester fiber, the nonporous polymer elastic body, and the porous thermoplastic polyurethane, and control the hardness of the thermoplastic polyurethane. It can be seen that the polishing rate and the polishing pad hardness can be easily adjusted. On the other hand, in the case of Comparative Example 1, since the hardness of the polyurethane to be impregnated is low, the storage elastic modulus during polishing is lowered and the polishing rate is lowered. In the case of Comparative Example 2, since the hardness of the thermoplastic polyurethane is low, the heat resistance is low, the cell structure is dissolved during polishing, the slurry retention is lowered, and the polishing rate is lowered.

  The polishing pad according to the present invention can be applied to polishing of various semiconductor devices, bare silicon, MEMS (Micro Electro Mechanical Systems), SiC semiconductors, and the like.

Claims (6)

Including a nonwoven fabric of polyester fiber, and a polymer elastic body impregnated in the nonwoven fabric,
The polymer elastic body includes a non-porous polymer elastic body and a porous thermoplastic polyurethane having a D hardness of 35 to 80,
The mass ratio of the nonwoven fabric of the polyester fiber is 0.4 to 0.6,
A polishing pad , wherein a mass ratio of the content of the nonporous polymer elastic body to the content of the porous thermoplastic polyurethane is 0.73 to 0.85.   The polishing pad according to claim 1, wherein the polyester fiber is a polybutylene terephthalate hollow fiber having an average single fiber fineness of 1 to 10 dtex. The polishing pad according to claim 1 or 2, wherein the porous thermoplastic polyurethane contains 80% or more of pores in a range of pore cross-sectional area of 11 to 100 µm ² . Wherein comprises porous thermoplastic polyurethane, a polymer diol, an organic diisocyanate,及Beauty, a thermoplastic polyurethane obtained by reacting a chain extender,
The polymer diol is poly (butylene adipate), poly (caprolactone), poly (ethylene glycol), poly (tetramethylene glycol), poly (nonamethylene adipate), poly (2-methyl-1,8-octamethylene adipate) ), Poly (2-methyl-1,8-octamethylene-co-nonamethylene adipate), at least one selected from the group consisting of poly (methylpentane adipate),
The organic diisocyanate contains at least one selected from the group consisting of 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, isophorone diisocyanate,
The chain extender is at least one selected from the group consisting of 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, and cyclohexanedimethanol. The polishing pad according to claim 1, comprising: The polishing pad according to claim 1, which has an apparent density of 0.35 to 0.50 g / cm ³ .   The polishing pad according to any one of claims 1 to 5, having a hardness of 60C to 90C.