Polishing pad and manufacturing method thereof

Abstract

The invention provides a polishing pad which can maintain the beneficial effects of the polishing pad, such as simplification of the management of a polishing liquid after polishing and simplification of a cleaning process of an object to be polished after polishing, and which can exhibit more excellent polishing capability. In this polishing pad, an object to be polished (W) contains a solid of an amorphous, crystalline, or amorphous-crystalline composite material. Each of the polishing particles (12) contains a specific particle having a chemical mechanical polishing effect on an object to be polished (W). A plurality of large pores (10b) are formed in the base material (10), the large pores (10b) being capable of opening to the polishing surface (14), communicating with the plurality of pores (10a), and having a volume larger than that of each of the pores (10a).

Description

Technical Field

[0001] The present invention relates to a polishing pad and a method for manufacturing the same. Background Art

[0002] Patent documents 1 to 3 disclose conventional polishing pads. Figure 22 As shown, there is a base material 90 and numerous abrasive particles 92. The base material 90 is mainly composed of resin and has a plurality of pores 90a. Examples of the resin used include polyvinylidene fluoride, epoxy resin, and PES (polyethersulfone). The abrasive particles 92 are made of silicon oxide and are retained within the base material 90 or within the pores 90a.

[0003] These polishing pads are manufactured through the first step, the second step, the third step and the fourth step. In the first step, a slurry containing a matrix resin, abrasive particles 92 and a solvent is prepared. In the second step, the slurry is formed into a sheet-like formed body. In the third step, the formed body is immersed in a replacement liquid, and the solvent in the formed body is replaced by the replacement liquid to form pores 90a and obtain a replacement body. In the fourth step, the replacement liquid is removed from the replacement body to obtain a polishing pad. When the polishing pad is grinding the object W, the front and / or back surface is trimmed by a dresser or the like to form a grinding surface 94.

[0004] Because the polishing pad thus obtained semi-fixedly holds the abrasive particles 92 on the base material 90, it is possible to perform a polishing method using a CMP (Chemical Mechanical Polishing) method using a polishing liquid that does not contain abrasive particles 92, or simply water. This method offers advantages over free-abrasive polishing methods that use a pad that does not contain abrasive particles and a polishing liquid that contains abrasive particles, such as simplified management of the polishing liquid after polishing and simplified cleaning of the workpiece after polishing.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-49256

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2021-61306

[0009] Patent Document 3: Japanese Patent No. 6243009 Summary of the Invention

[0010] Problems that the invention aims to solve

[0011] However, it is desirable that these conventional polishing pads exhibit even greater polishing capabilities. Specifically, even with increased polishing pressure to increase the amount of material removed per unit time, conventional polishing pads still struggle to achieve a sufficiently high polishing rate. Furthermore, conventional polishing pads are also limited in the time they can maintain a certain polishing rate. This results in a short lifespan, necessitating premature dressing to restore the reduced polishing rate, resulting in poor workability.

[0012] The present invention has been completed in view of the above-mentioned actual situation in the past, and its subject is to solve the following situation, that is, to provide a polishing pad that can maintain the beneficial effects of the polishing pad, such as simplifying the management of the polishing liquid after polishing and simplifying the cleaning process of the polished object after polishing, and can exert a better polishing ability.

[0013] Means of solving the problem

[0014] The polishing pad of the present invention is characterized by comprising: a base material having a resin as a main component and having a plurality of pores; and numerous abrasive particles held in the base material or in the pores; the polishing pad constituting a polishing surface for polishing an object to be polished,

[0015] The above-mentioned object to be ground comprises amorphous, crystalline or amorphous-crystalline composite solid.

[0016] Each of the abrasive particles comprises specific particles having a chemical mechanical polishing effect on the object to be polished.

[0017] A plurality of large pores are formed in the base material. The large pores are capable of opening on the polishing surface and communicating with the plurality of fine pores, and have a volume larger than that of each of the fine pores.

[0018] The grinding pad of the present invention is not only formed with a plurality of pores in the base material, but also formed with a plurality of large air pores connected with the plurality of pores. The volume of the large air pores is larger than each pore. In addition, if the front and / or back of the grinding pad is trimmed by a dresser etc. when grinding the object to be grinded, the large air pores can be opened on the grinding surface. According to the test of the inventors, if the grinding pressure is increased to increase the grinding amount per unit time of the object to be grinded, the grinding rate is also fully increased by using this grinding pad. In addition, by using this grinding pad, the time for grinding the object to be grinded at a certain grinding rate is longer than that of previous grinding pads. That is, the life of this grinding pad is longer and it is not necessary to dress it so frequently, so that excellent workability can be brought into play.

[0019] In addition, similar to the conventional polishing pads, this polishing pad semi-fixedly holds the abrasive particles in the base material, allowing the use of a polishing liquid that does not contain abrasive particles or pure water as the polishing liquid, and the CMP method can be used for polishing. Therefore, when this polishing pad is used to polish an object, compared to the case of polishing the object using a free abrasive particle polishing method, it has the advantageous effect of simplifying the management of the polishing liquid after polishing and simplifying the cleaning process of the object after polishing.

[0020] Therefore, according to this polishing pad, while maintaining the advantageous effects of the polishing pad such as simplified management of the polishing liquid after polishing and simplified cleaning steps of the polished object after polishing, it is possible to exhibit a more excellent polishing performance.

[0021] The inventors of this case speculate that the reason why the polishing pad of the present invention can exert a higher polishing ability is the following micro-pumping effect of the abrasive particles. That is, the polishing pad replenishes abrasive particles from the base material or the pores to the large air pores opening on the polishing surface while the polishing object is pressed against the polishing surface with a specified load while the polishing object is relatively moved with the polishing object. Moreover, during this period, the abrasive particles retained in the large air pores opening on the polishing surface move to the polishing surface. That is, in the polishing pad of the present invention, the abrasive particles include inactive abrasive particles still retained in the base material and the pores, standby abrasive particles replenished from the base material or the pores into the large air pores and retained in the large air pores, and active abrasive particles moving from the large air pores to the polishing surface. In the polishing pad of the present invention, the active abrasive particles present in the polishing surface are increased compared to previous polishing pads by the micro-pumping effect of the abrasive particles, so that the polishing ability is improved.

[0022] On the other hand, in conventional polishing pads, Figure 22 As shown, a plurality of abrasive particles 92 are present in the base material 90 and the pores 90a. However, the abrasive particles 92 include inactive abrasive particles 92a that remain within the base material 90 and the pores 90a, standby abrasive particles 92b that, despite being trimmed and exposed to the grinding surface 94, do not contribute to grinding, and active abrasive particles 92c that, after being trimmed and exposed to the grinding surface 94, contribute to grinding. The inactive abrasive particles 92a that remain within the base material 90 and the pores 90a are difficult to move to the grinding surface 94, and the number of standby abrasive particles 92b is relatively small. Only the active abrasive particles 92c exert a chemical mechanical polishing effect on the workpiece W. Therefore, even if conventional polishing pads polish the workpiece W by pressing the workpiece W against the grinding surface 94 with a predetermined load while moving relative to the workpiece W, it is difficult to replenish the active abrasive particles 92c present on the grinding surface 94. Therefore, conventional polishing pads have fewer active abrasive particles 92c present on the grinding surface 94 than the polishing pad of the present invention, resulting in lower polishing performance.

[0023] The present inventors have confirmed the effects of the present invention when the object to be polished comprises a solid of amorphous, crystalline, or amorphous-crystalline composite material, and each abrasive particle comprises a specific particle having a CMP effect on the object to be polished.

[0024] The method for manufacturing a polishing pad of the present invention is characterized by comprising: a first step of preparing a slurry containing a matrix resin, polishing particles, and a solvent;

[0025] The second step is to shape the slurry into a sheet-like formed body;

[0026] In a third step, the molded body is immersed in a replacement liquid to replace the solvent in the molded body with the replacement liquid, thereby forming pores to obtain a replacement body; and

[0027] A fourth step is to remove the replacement liquid from the replacement body to obtain a polishing pad having a base material composed mainly of the base material resin and having a plurality of pores, and numerous abrasive particles held in the base material or the pores;

[0028] The abrasive particles include specific particles that have a chemical mechanical polishing effect on amorphous, crystalline or amorphous-crystalline composite solids.

[0029] The slurry contains a pore-forming agent capable of forming numerous large pores that communicate with the plurality of fine pores and have a volume larger than that of each of the fine pores in the third step.

[0030] The polishing pad of the present invention can be produced using the manufacturing method of the present invention. When an oily solvent is used, a water-soluble substance can be used as the pore-forming agent. Examples of water-soluble pore-forming agents include powdered sugar (pulverized sugar) and corn starch. The size of the pores can be adjusted by adjusting the particle size of the pore-forming agent.

[0031] Effects of the Invention

[0032] According to the polishing pad of the present invention, the advantageous effects of the polishing pad such as the simplified management of the polishing liquid after polishing and the simplified cleaning process of the polished object after polishing can be maintained, and a more excellent polishing ability can be exerted. In addition, according to the manufacturing method of the present invention, the polishing pad of the present invention can be manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic enlarged cross-sectional view of the polishing pad of Example 1-1.

[0034] Figure 2 This is a 30x SEM photograph of the polishing surface of the polishing pad of Example 1-1 in Test 1.

[0035] Figure 3This is a 500x SEM photograph of the polishing surface of the polishing pad of Example 1-1 in Test 1.

[0036] Figure 4 This is a graph showing the relationship between the polishing pressure and the polishing rate in the polishing methods of Example 1-1, Comparative Example 1-1, and Comparative Example 1-2 of Test 1.

[0037] Figure 5 Graph showing the relationship between polishing pressure and surface roughness in the polishing methods of Example 1-1, Comparative Example 1-1, and Comparative Example 1-2 of Test 1.

[0038] Figure 6 This is a graph showing the relationship between the polishing time and the polishing rate in the polishing methods of Example 1-1 and Comparative Example 1-2 of Test 2.

[0039] Figure 7 The polishing pad of Example 1-1 is Figure 1 Magnified cross-sectional view of the same.

[0040] Figure 8 This is an image obtained by differentiating (Sobel processing) a white interference microscope photograph of the polished surface of the object to be polished after the polishing method of Example 1-1 was implemented in Test 3 and then washed.

[0041] Figure 9 This is an image obtained by differentiating (Sobel processing) a white interference microscope photograph of the polished surface of the object to be polished after the polishing method of Comparative Example 1-1 in Test 3 was implemented and then washed.

[0042] Figure 10 This is a 100x SEM photograph of the polished surface of the cleaned polishing pad after the polishing method of Example 1-1 was implemented in Test 4.

[0043] Figure 11 This is a 1000x SEM photograph of the polished surface of the cleaned polishing pad after the polishing method of Example 1-1 was implemented in Test 4.

[0044] Figure 12 This is a graph showing the relationship between the average particle size of the polishing particles and the polishing rate in the polishing methods of Example 1-1, Comparative Example 1-1, and Comparative Example 1-2 of Test 5.

[0045] Figure 13 This is a graph showing the relationship between the average particle size of the polishing particles and the surface roughness in the polishing methods of Example 1-1, Comparative Example 1-1, and Comparative Example 1-2 of Test 5.

[0046] Figure 14 This is a graph showing the relationship between the ratio of the resin to the pores and the polishing rate in Test 6.

[0047] Figure 15 This is a graph showing the relationship between the ratio of the resin to the pores and the durometer hardness in Test 6.

[0048] Figure 16 This is a graph showing the polishing rates in the polishing methods of Example 2-1 and Comparative Example 2-1 of Test 7.

[0049] Figure 17 This is a graph showing the surface roughness in the polishing methods of Example 2-1 and Comparative Example 2-1 of Test 7.

[0050] Figure 18 This is a graph showing the polishing rates in the polishing methods of Example 2-1, Comparative Example 2-2, and Comparative Example 2-1 of Test 8.

[0051] Figure 19 This is a graph showing the surface roughness in the polishing methods of Example 2-1, Comparative Example 2-2, and Comparative Example 2-1 in Test 8.

[0052] Figure 20 This is a graph showing the relationship between the average particle size of the polishing particles and the polishing rate in the polishing methods of Example 3-1, Comparative Example 3-1, and Comparative Example 3-2 of Test 9.

[0053] Figure 21 This is a graph showing the relationship between the average particle size of the polishing particles and the surface roughness in the polishing methods of Example 3-1, Comparative Example 3-1, and Comparative Example 3-2 of Test 9.

[0054] Figure 22 This is a schematic enlarged cross-sectional view of a conventional polishing pad. DETAILED DESCRIPTION

[0055] As the resin constituting the matrix, polyethersulfone (PES), polysulfone (PSU), polyvinylidene fluoride (PVDF), polyvinyl fluoride, ethylene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, polyethylene, polymethyl methacrylate, polycarbonate, etc. These resins may be used alone or in combination of two or more.

[0056] The solvent may be any solvent that can dissolve the resin constituting the matrix, and examples thereof include N-methyl-2-pyrrolidone, 2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0057] According to experiments conducted by the inventors, the object to be polished can be, specifically, synthetic quartz, lithium tantalate wafers, silicon wafers, or crystal, which are examples of amorphous, crystalline, or amorphous-crystalline composite solids.

[0058] When the polishing material is a glass containing silicon, such as synthetic quartz or crystal, at least one of cerium oxide (CeO2), red iron oxide (ferric oxide, Fe2O3), and manganese oxide (ferric oxide, Mn2O3) can be used as specific particles. Glass can be amorphous, crystalline, or a composite material of amorphous and crystalline. For example, according to "Red Lead as an Abrasive" (Funabashi Watari, Precision Machinery, 19 (1940), p. 342) and "Glass Abrasives" (Hana Kenzo, NEW GLASS, Vol. 27 (2012), No. 106), it is known that red iron oxide has a CMP effect on glass. For example, according to Japanese Patent Application Laid-Open Nos. 10-071571, 2002-210640, 2014-084420, 2014-118468, and 2015-140402, it is known that manganese oxide has a CMP effect on glass.

[0059] When the object to be polished is a lithium tantalate wafer or a silicon wafer, at least one of silicon oxide (silicon dioxide, SiO2), cerium oxide (ceria, CeO2), titanium oxide (TiO2), chromium [III] oxide (Cr2O3), etc. can be used as specific particles.

[0060] According to the inventors' experimental results, the inner diameter of the portion of the pore that connects to the large pore is preferably 7-25 μm, the length of the largest portion of the large pore's inner diameter is 70-500 μm, and the abrasive particle size is 0.06-1.71 μm. It is speculated that within these ranges, the micropumping effect of the abrasive particles is more likely to occur.

[0061] Furthermore, according to the test results of the inventors, the ratio of the base material to the volume of fine pores and large pores is preferably 0.205 or less, and the durometer hardness (type D) is 39.7 or less. It is speculated that these conditions cause deformation of the base material, thereby facilitating the micro-pumping effect of the abrasive particles.

[0062] In the first step, the matrix resin, abrasive particles, and solvent may be mixed simultaneously to form a slurry. However, it is preferred to preliminarily mix the abrasive particles with the solvent to disperse the abrasive particles in the solvent, and then mix this dispersion with the matrix resin to form a slurry. This facilitates the presence of the abrasive particles in the pores, making it easier to produce a micro-pumping effect.

[0063] In the first step, additives may be added to the slurry as needed. Examples of the additives include glycerin for adjusting the solubility of the resin in the solvent.

[0064] The second step is not particularly limited, and a forming device such as a T-die is used to form a sheet-like molded body. As for the forming method, as long as the thickness can be made uniform to a certain extent, it is not limited to this.

[0065] In the third step, for example, the formed body is immersed in a water tank filled with temperature-controlled ion-exchanged water for a predetermined period of time, thereby inducing a nucleation-growth phase separation process. This results in a large amount of a solvent-rich phase containing isolated, spherical particles with irregular sizes and / or relative positions, dispersed within the resin-rich phase. At this point, the solvent in the solvent-rich phase is replaced with water by diffusion into the replacement fluid.

[0066] In the third step, when an aqueous solvent is used, an aqueous liquid such as ion-exchanged water can be used as a replacement liquid, and the molded body can be immersed in the replacement liquid. As a result, the solvent-rich phase is dispersed in the resin-rich phase through a nucleation-growth phase separation process, and the solvent in the solvent-rich phase is replaced with the replacement liquid to remove the solvent from the molded body. At this time, each isolated solvent-rich phase is connected to the outside of the molded body through the pores formed in the resin-rich phase, and the solvent is replaced with the replacement liquid through the pores. When the solvent is removed from the molded body in this way, the resin-rich phase shrinks and solidifies, and tiny continuous pores are formed in the resin-rich phase. In addition, by using an aqueous liquid such as ion-exchanged water as a replacement liquid and immersing the molded body in the replacement liquid, the water-soluble pore-forming agent can also be removed at the same time.

[0067] The compact after removal of the solvent and the pore forming agent is processed into a polishing pad by passing through the fourth step. When the polishing pad is polishing an object, the front and / or back surface is dressed by a dresser or the like to form a polishing surface.

[0068] (Test 1)

[0069] <Step 1>

[0070] Prepare the following base material resin, abrasive particles, solvent, and pore forming agent.

[0071] (Base material resin)

[0072] PES (polyethersulfone)

[0073] (Abrasive particles, special particles)

[0074] Cerium oxide particles (average particle size: 0.75 μm)

[0075] (Solvent)

[0076] N-Methyl-2-pyrrolidone

[0077] (pore forming agent)

[0078] powdered sugar

[0079] The matrix resin, abrasive particles, solvent, and pore-forming agent were mixed in the proportions (parts by mass) listed in Table 1. In Example 1-1, the abrasive particles were first dispersed in the solvent, and this dispersion and the pore-forming agent were then mixed into the matrix resin. In Comparative Example 1-2, in which the polishing pad did not have large pores 10b, the abrasive particles were first dispersed in the solvent, and this dispersion was then mixed into the matrix resin. In this manner, slurries were obtained for Example 1-1 and Comparative Example 1-2.

[0080]

[0081] <Step 2>

[0082] Using the obtained slurries, sheet-shaped molded bodies of Example 1-1 and Comparative Example 1-2 were obtained using a T-die.

[0083] <Step 3>

[0084] Each molded body was immersed in temperature-controlled ion-exchange water stored in a water tank for a predetermined period of time. This process caused a nucleation-growth phase separation process to occur within each molded body, dispersing a large number of isolated, spherical, solvent-rich phases within the resin-rich phase. The ion-exchange water also replaced the solvent within each molded body, removing the solvent from each molded body. In the molded body of Example 1-1, the pore-forming agent was also removed at this time. Thus, each replaced body was obtained.

[0085] <Step 4>

[0086] The obtained replacement bodies were left in the air at room temperature for about 2 days to remove moisture from the replacement bodies, thereby obtaining polishing pads of Example 1-1 and Comparative Example 1-2. Each polishing pad was a disk-shaped pad with a diameter of 300 mm and a thickness of 2 mm.

[0087] The surface of the polishing pads of Example 1-1 and Comparative Example 1-2 was dressed using a dresser, as shown in FIG. Figure 1 and Figure 22 As shown, the polishing surfaces 14 and 94 are formed to polish the workpiece W. The dresser has #400 diamond particles.

[0088] The SEM photograph of the cross section of the polishing pad of Example 1-1 parallel to the polishing surface 14 is shown in FIG. Figure 2 and Figure 3 .from Figure 2 and Figure 3 It can be seen that the polishing pad of Example 1-1 is as follows Figure 1The polishing pad of Example 1-1 includes a base material 10 and abrasive particles 12. The base material 10 comprises a resin and is formed with a plurality of fine pores 10a and a plurality of large pores 10b. The volume percentages of the resin, abrasive particles, fine pores 10a, and large pores 10b in the polishing pad of Example 1-1 are shown in Table 2. The durometer hardness (type D) of the polishing pad of Example 1-1 is also shown in Table 2.

[0089]

[0090] The polishing pad of Comparative Example 1-2 is as follows Figure 22 The polishing pad of Comparative Example 1-2 includes a base material 90 and abrasive particles 92. The base material 90 comprises a resin and is formed with a plurality of pores 90. In the polishing pad of Comparative Example 1-2, since the slurry of Comparative Example 1-2 does not contain a pore-forming agent, large pores 10b are not formed in the base material 90, as in the base material 10 of Example 1-1. The volume percentages of the resin, abrasive particles, and pores 90 in the polishing pad of Comparative Example 1-2 are shown in Table 2. The durometer hardness (type D) of the polishing pad of Comparative Example 1-2 is also shown in Table 2.

[0091] After the polishing pads of Example 1-1 and Comparative Example 1-2 were dressed for 2 minutes to shape the polishing surfaces 14 and 94, polishing tests were performed under the following conditions to investigate the relationship between the polishing pressure (kPa) and the polishing rate (μm / minute), and the relationship between the polishing pressure and the surface condition of the workpiece W after processing. The surface condition of the workpiece W after processing was evaluated using surface roughness Sa (nm). The polishing test using the polishing pad of Example 1-1 was set as the polishing method of Example 1-1, and the polishing test using the polishing pad of Comparative Example 1-2 was set as the polishing method of Comparative Example 1-2.

[0092] Device: Engis EJW-380 (φ380 single-side grinding machine)

[0093] Workpiece W: 1 piece of synthetic quartz (φ65 mm × thickness 5 mm)

[0094] Platen speed: 60 rpm

[0095] Workpiece W rotation speed: 60 rpm

[0096] Test time: 30 minutes

[0097] Grinding fluid: tap water (10 ml / min)

[0098] Grinding pressure: 20 (kPa), 40 (kPa), 60 (kPa)

[0099] In addition, a polishing test was also conducted under the above conditions using a free abrasive polishing method using a hard polyurethane pad containing no abrasive particles and a polishing liquid containing 5% by mass of cerium oxide. The polishing test of the free abrasive polishing method was set as the polishing method of Comparative Example 1-1. The results are shown in FIG. Figure 4 、 Figure 5 , Table 3 and Table 4.

[0100]

[0101] from Figure 4 As shown in Table 3, in the polishing method of Example 1-1, increasing the polishing pressure to increase the amount of workpiece W polished per unit time increases the polishing rate, which increases approximately proportionally. In contrast, in the polishing methods of Comparative Examples 1-1 and 1-2, even when the polishing pressure is increased, the polishing rate remains relatively low and approximately the same.

[0102] In addition, from Figure 5 As can be seen from Table 4, the polishing method of Example 1-1 can achieve a surface roughness Sa substantially similar to that of the polishing method of Comparative Example 1-2. In contrast, in the polishing method of Comparative Example 1-1, which is a loose abrasive polishing method, it is presumed that the loose abrasive particles roughened the polished surface of the workpiece W, resulting in a poorer surface roughness Sa.

[0103] (Test 2)

[0104] As in Test 1, the polishing pads of Example 1-1 and Comparative Example 1-2 were subjected to 2 minutes of dressing to shape the polishing surfaces 14 and 94, and then a polishing test was performed under the following conditions to investigate the relationship between the polishing time (minutes) and the polishing rate (μm / minute). The polishing test using the polishing pad of Example 1-1 was set as the polishing method of Example 1-1, and the polishing test using the polishing pad of Comparative Example 1-2 was set as the polishing method of Comparative Example 1-2. The results are shown in FIG. Figure 6 And Table 5.

[0105] Device: 9B double-sided grinding machine

[0106] Workpiece W: 5 pieces of synthetic quartz (φ100 mm × thickness 2 mm) (25 pieces in total on 5 carriers)

[0107] Lower platen speed: 40 rpm

[0108] Grinding fluid: tap water (50 ml / min)

[0109] Grinding pressure: 8.3 (kPa)

[0110]

[0111] from Figure 6As can be seen from Table 5, the polishing method of Example 1-1 can polish the workpiece W at a certain polishing rate for a much longer period of time than the polishing method of Comparative Example 1-2. In other words, the polishing pad of Example 1-1 has a longer life and does not require as frequent dressing, thus achieving excellent workability.

[0112] In the grinding method of Example 1-1, the reasons for these effects are speculated as follows. Figure 1 and Figure 7 As shown, while the workpiece W is being polished by pressing the workpiece W against the polishing surface 14 of the polishing pad at a predetermined load while the workpiece W is being moved relative to the polishing pad, abrasive particles 12 are replenished from the base material 10 or the fine pores 10a into the large pores 10b opening on the polishing surface 14. Furthermore, during this period, the abrasive particles 12 retained in the large pores 10b opening on the polishing surface 14 are moved to the polishing surface 14 by the flow of the polishing liquid generated by the workpiece W. That is, in the polishing method of Example 1-1, the abrasive particles 12 include inactive abrasive particles 12a retained in the base material 10 or the fine pores 10a, standby abrasive particles 12b replenished from the base material 10 or the fine pores 10a into the large pores 10b and retained in the large pores 10b, and active abrasive particles 12c moved from the large pores 10b to the polishing surface 14. In the polishing method of Example 1-1, due to the micro-pumping effect of the polishing particles 12 , the active polishing particles 12 c present on the polishing surface 14 are sequentially replenished by the standby polishing particles 12 b , thereby increasing the polishing capability compared to conventional polishing pads.

[0113] (Test 3)

[0114] Each workpiece W after grinding in Test 1 was cleaned with pure water and a PVA sponge. The image obtained by differentiating (Sobel processing) the white interference microscope photograph of the ground surface of the workpiece W after grinding and cleaning using the grinding method of Example 1-1 is shown in FIG. Figure 8 The image obtained by differentiating (Sobel processing) a white interference microscope photograph of the polished surface of the workpiece W after polishing and cleaning using the polishing method of Comparative Example 1-1, which is a free abrasive polishing method, is shown in FIG. Figure 9 .

[0115] The semi-fixed polishing method of Example 1-1 and the free abrasive polishing method of Comparative Example 1-1 both utilize cerium oxide particles for CMP polishing, and therefore abrasive particles inevitably remain on the workpiece W. However, according to Figure 8 and Figure 9 It can be seen that the workpiece W polished by the semi-fixed polishing method of Example 1-1 is less likely to have residual abrasive grains than the workpiece W polished by the loose abrasive polishing method of Comparative Example 1-1.

[0116] Therefore, it can be seen that if the workpiece W is ground using the grinding method of Example 1-1, compared with the case where the workpiece W is ground using the free abrasive grain grinding method of Comparative Example 1-1, it can achieve advantageous effects such as simplifying the management of the grinding liquid after grinding and simplifying the cleaning process of the workpiece W after grinding.

[0117] (Test 4)

[0118] The polishing pad of Example 1-1 after polishing in Test 1 was ultrasonically cleaned to remove the polishing particles on the polishing surface 14. A 100x SEM photograph of the polishing surface is shown in FIG. Figure 10 , the 1000x SEM photograph is shown in Figure 11 .

[0119] from Figure 10 and Figure 11 It was confirmed that the inner diameter of the fine pores 10a was 3 to 20 μm, and the inner diameter of the large pores 10b was 100 to 400 μm.

[0120] (Test 5)

[0121] The grinding pressure was set to 40 (kPa), and the average particle size of the cerium oxide particles as the grinding particles (specific particles) was changed, and the other conditions were the same as those of Test 1 to carry out the grinding test. In addition, the relationship between the average particle size (μm) of the grinding particles and the grinding rate (μm / min), and the relationship between the average particle size (μm) of the grinding particles and the surface state of the workpiece W after processing were investigated. The grinding test using the grinding pad of Example 1-1 was set as the grinding method of Example 1-1, the grinding test using the free abrasive grinding method of the hard polyurethane pad of Comparative Example 1-1 was set as the grinding method of Comparative Example 1-1, and the grinding test using the grinding pad of Comparative Example 1-2 was set as the grinding method of Comparative Example 1-2. The results are shown in Figure 12 、 Figure 13 , Table 6 and Table 7.

[0122]

[0123]

[0124] from Figure 12 As shown in Table 6, the polishing method of Example 1-1 achieved the highest polishing rate when using abrasive particles with an average particle size of 0.75 μm. This is presumably because when using abrasive particles with an average particle size of 0.75 μm, the abrasive particles 12 are more likely to undergo a micro-pumping effect through the fine pores 10a and large pores 10b of Example 1-1.

[0125] In addition, from Figure 13As shown in Table 7, the polishing method of Example 1-1, when using abrasive particles with an average particle size of 0.26 μm, 0.75 μm, and 1.71 μm, can achieve a surface roughness Sa substantially similar to that of the polishing method of Comparative Example 1-1, which is a free abrasive polishing method. In contrast, the polishing method of Comparative Example 1-2, when using abrasive particles with an average particle size of 0.75 μm or 1.71 μm, exhibits a poorer surface roughness Sa.

[0126] The results of Experiments 4 and 5 show that the polishing method of Example 1-1 achieved a high polishing rate within the range of 0.26 to 1.71 μm, centered around an average particle size of 0.75 μm. Even with abrasive particles of any average particle size, the surface roughness was as fine as that achieved by the free abrasive polishing method of Comparative Example 1-1. This suggests that if the average particle size is less than 0.26 μm, the abrasive particles will enter the pores 10a on the polishing surface of the polishing pad, preventing the chemical mechanical polishing effect from being achieved. Furthermore, if the average particle size is greater than 1.71 μm, the abrasive particles will become lodged in the pores 10a and will not be able to reach the larger pores 10b.

[0127] According to the inventors' knowledge, when using abrasive particles with an average particle size of 0.06 to 1.71 μm, in order to allow the abrasive particles to move from the fine pores 10a to the large pores 10b through the micropumping effect, the inner diameter of the portion of the fine pores 10a communicating with the large pores 10b is preferably 7 to 25 μm.

[0128] The reason for setting the minimum value of the inner diameter of the connected portion to 7 μm is as follows. The portion where the pores and the large air pores are connected is set as a connecting port. It is considered that the connecting port is not circular but has a minimum value and a maximum value. If the minimum value is 7 μm, even in the case where the abrasive particles 12 with a diameter of 1.71 μm are attached to a circle of the connecting port, 3.58 μm, which is obtained by subtracting twice the diameter of the abrasive particles 12 (3.42 μm) from the inner diameter of the connecting port, can also be the maximum value. In the case where the abrasive particles 2 are particle aggregates, the diameter of the abrasive particles 12 is 3.42 μm, and there is still a margin of about 5% relative to the maximum value of 3.58 μm of the connecting port and it can pass through the connecting port. In this way, if the minimum value of the inner diameter of the connecting port is 7 μm, a certain degree of passage of the abrasive particles 12 can be expected.

[0129] The reason for setting the maximum value of the inner diameter of the connecting port to 25 μm is as follows. When studying the maximum value of the connecting port, the large air pore 10b can be approximated as a sphere inscribed in the edge of a regular icosahedron, and the connecting port can be regarded as each face of the regular icosahedron. Since each face of the regular icosahedron is an equilateral triangle, the connecting port can be regarded as the inscribed circle of the equilateral triangle. If the length of the longest part of the inner diameter of the large air pore 10b is 70 μm, the length of one side of the inscribed icosahedron is 70 ÷ 2 ÷ 0.809 = 43.3 (μm), and the diameter of the inscribed circle of the equilateral triangle is √3 ÷ 3 × 43.3 = 25.0 (μm). Therefore, the maximum inner diameter of the connecting port in which the maximum number (20) of the grinding particles 12 can be closely connected is 25 μm.

[0130] In addition, when using abrasive particles 12 having an average particle size of 0.06 to 1.71 μm, in order to allow the abrasive particles 12 retained in the air pores 10b to move to the grinding surface 14 along with the flow of the polishing liquid accompanying the movement of the workpiece W on the grinding surface 14 of the grinding pad, it is preferred that the length of the longest inner diameter portion of the air pores 10b is 70 to 500 μm. Generally speaking, the grinding pad is trimmed before use, and the unevenness of the grinding surface 14 at this time is sometimes trimmed to about 35 μm. In this case, if the spherical air pores 10b are exposed on the grinding surface 14 and become hemispherical, they will be hidden in the unevenness. Therefore, if the inner diameter of the air pores 10b is not more than 70 μm (depth 35 μm), the standby effect of the abrasive particles is less. In addition, when the spherical air pore 10b is exposed on the grinding surface 14 and becomes hemispherical, if the inner diameter of the air pore 10b is greater than 500 μm (depth 250 μm), the flow of the grinding fluid accompanying the movement of the workpiece W on the grinding surface 14 of the grinding pad cannot reach the bottom of the air pore 10b, and thus the standby grinding particles 12b cannot move to the grinding surface 14.

[0131] (Test 6)

[0132] As in Test 1, the polishing pads of Tests 1 to 4 were manufactured by changing the ratio of the base material to the pores. The ratio of the polishing particles in each polishing pad was 19.5% by volume, the same as in Example 1-1, and the ratio of the large pores 10b was 28.4% by volume, the same as in Example 1-1. The polishing test was performed using each polishing pad of Tests 1 to 4, with the polishing pressure set to 60 (kPa) and other conditions set to the same as in Test 1. Then, the relationship between the ratio (volume ratio) of the base material to the pores and the polishing rate (μm / min), and the relationship between the ratio (volume ratio) of the base material to the pores and the durometer hardness (type D) were investigated. The results are shown in Figure 14 、 Figure 15 and Table 8.

[0133]

[0134] from Figure 14 、 Figure 15 As shown in Table 8, samples 1 and 2 achieved excellent polishing rates. This shows that the ratio of the base material 10 to the fine pores 10a and large pores 10b is preferably 0.205 volume ratio or less, and the durometer hardness (type D) is preferably 39.7 or less.

[0135] (Test 7)

[0136] A polishing pad of Example 2-1 was produced in the same manner as in the polishing pad of Example 1-1, using silicon oxide particles (average particle size: 0.25 μm) as the abrasive particles and the specific particles.

[0137] The workpiece W was a lithium tantalate (LT) wafer (φ100 mm × thickness 2 mm), and the polishing pressure was set to 60 (kPa). The polishing surface 14 of the polishing pad of Example 2-1 was dressed for 2 minutes as in Test 1, and then a polishing test was conducted under the same conditions as in Test 1. The polishing test using the polishing pad of Example 2-1 was referred to as the polishing method of Example 2-1.

[0138] In addition, a grinding test was also conducted under the above conditions using a free abrasive grinding method using a non-woven fabric pad containing no abrasive particles and a grinding liquid containing 12.5% ​​by mass of colloidal silica. The grinding test of this free abrasive grinding method was set as the grinding method of Comparative Example 2-1. Then, the grinding rate (μm / min) and the surface state of the workpiece W after processing were investigated. The results are shown in FIG. Figure 16 and Figure 17 .

[0139] from Figure 16 and Figure 17 It can be seen that the effects of the present invention can be confirmed even when the workpiece W is a lithium tantalate wafer.

[0140] (Test 8)

[0141] A polishing pad of Comparative Example 2-2 was produced in the same manner as the polishing pad of Comparative Example 1-2, using silicon oxide particles (average particle size: 0.25 μm) as the abrasive particles and the specific particles.

[0142] The workpiece W was a silicon wafer (φ100 mm × thickness 0.4 mm), the polishing liquid was 0.1 mol / L KOH (10 ml / min), and the polishing pressure was 10 (kPa). After forming polished surfaces 14 and 94 on the polishing pads of Example 2-1 and Comparative Example 2-2 in the same manner as in Experiment 1, a polishing test was conducted 2 minutes later under the same conditions as in Experiment 1. The polishing test using the polishing pad of Example 2-1 was designated as the polishing method of Example 2-1, and the polishing test using the polishing pad of Comparative Example 2-2 was designated as the polishing method of Comparative Example 2-2.

[0143] In addition, a grinding test was also conducted under the above conditions using a free abrasive grinding method using a non-woven fabric pad containing no abrasive particles and a grinding liquid containing 12.5% ​​by mass of colloidal silica and 0.1 mol / L of KOH. The grinding test of this free abrasive grinding method was set as the grinding method of Comparative Example 2-1. Then, the grinding rate (μm / min) and the surface state of the workpiece W after processing were investigated. The results are shown in FIG. Figure 18 and Figure 19 .

[0144] from Figure 18 and Figure 19 It can be seen that the effects of the present invention can be confirmed even when the workpiece W is a silicon wafer.

[0145] (Test 9)

[0146] Polishing pads of Example 3-1 and Comparative Example 3-2 were produced in the same manner as in Test 1 using cerium oxide particles (average particle size: 0.75 μm) as abrasive particles and specific particles and PVDF (polyvinylidene fluoride) as a matrix resin.

[0147] The volume percentages of the resin, abrasive particles, fine pores 10a, and large pores 10b in the polishing pad of Example 3-1 are shown in Table 9. Furthermore, the durometer hardness (Type D) of the polishing pad of Example 3-1 is also shown in Table 9. The volume percentages of the resin, abrasive particles, and fine pores 90 in the polishing pad of Comparative Example 3-2 are also shown in Table 9. Furthermore, the durometer hardness (Type D) of the polishing pad of Comparative Example 3-2 is also shown in Table 9.

[0148]

[0149] The workpiece W was a crystal (φ100 mm × thickness 1 mm) (1 piece), the polishing liquid was tap water, and the polishing pressure was 20 (kPa). After forming the polishing surfaces 14 and 94 on the polishing pads of Example 3-1 and Comparative Example 3-2 in the same manner as in Test 1, a polishing test was performed 2 minutes later under the same conditions as in Test 1. The polishing test using the polishing pad of Example 3-1 was designated as the polishing method of Example 3-1, and the polishing test using the polishing pad of Comparative Example 3-2 was designated as the polishing method of Comparative Example 3-2.

[0150] In addition, a polishing test was conducted under the above-mentioned conditions using a free abrasive polishing method using a hard polyurethane pad containing no abrasive particles and a polishing liquid containing 5% by mass of cerium oxide. The polishing test using this free abrasive polishing method was used as the polishing method of Comparative Example 3-1. The results are shown in FIG. Figure 20 、 Figure 21 , Table 10 and Table 11.

[0151]

[0152] from Figure 20 、 Figure 21 As can be seen from Tables 10 and 11, the effects of the present invention can be observed even when the workpiece W is made of crystal.

[0153] As can be seen from the above, the polishing pads of Examples 1-1, 2-1, and 3-1 can maintain the advantageous effects of the polishing pad, such as simplifying the management of the polishing liquid after polishing and simplifying the cleaning process of the polished object W after polishing, while exhibiting even better polishing performance. Furthermore, it can be seen that the polishing pads of Examples 1-1, 2-1, and 3-1 can be manufactured using the above-described manufacturing method.

[0154] The present invention has been described above based on Experiments 1 to 9. However, the present invention is not limited to the above Experiments 1 to 9 or Examples 1-1, 2-1, and 3-1, and can be modified appropriately without departing from the spirit and scope of the present invention.

[0155] Industrial applicability

[0156] The present invention can be used in a method for grinding amorphous, crystalline or amorphous-crystalline composite solids.

[0157] Description of Reference Numerals

[0158] 10: Base material

[0159] 10a: fine pores

[0160] 14: Grinding surface

[0161] 12: Abrasive particles, specific particles (12a: unused abrasive particles, 12b: standby abrasive particles, 12c: used abrasive particles)

[0162] W: object to be ground (workpiece)

[0163] 10b: Large pores

Claims

1. A polishing pad, characterized in that: have: a base material having a resin as a main component and having a plurality of pores; and Countless abrasive particles are retained in the base material or the pores; The polishing pad forms a polishing surface for polishing the object to be polished. The object to be ground comprises amorphous, crystalline or amorphous-crystalline composite solid. Each of the abrasive particles comprises specific particles having a chemical mechanical polishing effect on the object to be polished. A plurality of large pores are formed in the base material. The large pores can open on the polishing surface and communicate with the plurality of fine pores, and have a volume larger than that of each of the fine pores.

2. The polishing pad according to claim 1 , wherein while the object to be polished is polished by pressing the object to be polished against the polishing surface with a specified load while moving relative to the object to be polished, the polishing particles are replenished from the base material or the pores into the large pores opening on the polishing surface, and the polishing particles retained in the large pores opening on the polishing surface move to the polishing surface.

3. The polishing pad according to claim 2, wherein The inner diameter of the portion of the fine pore communicating with the large pore is 7 μm to 25 μm, The length of the longest inner diameter portion of the large air pore is 70 μm to 500 μm, The average particle size of the abrasive particles is 0.06 μm to 1.71 μm.

4. The polishing pad according to claim 2, wherein The base material has a volume ratio of 0.205 or less relative to the fine pores and the large pores, is D-type, and has a durometer hardness of 39.7 or less.

5. The polishing pad according to claim 1, wherein The object to be ground is synthetic quartz. The polishing pad according to claim 1 , wherein: The object to be ground is a lithium tantalate wafer.

7. The polishing pad according to claim 1, wherein The object to be ground is a silicon wafer.

8. The polishing pad according to claim 1, wherein The object to be ground is crystal.

9. A method for manufacturing a polishing pad, characterized in that: have: In the first step, a slurry containing a matrix resin, abrasive particles, and a solvent is prepared; The second step is to shape the slurry into a sheet-shaped body; In a third step, the molded body is immersed in a replacement liquid, and the replacement liquid replaces the solvent in the molded body to form pores, thereby obtaining a replacement body; and A fourth step is to remove the replacement liquid from the replacement body to obtain a polishing pad having a base material having the base material resin as a main component and formed with a plurality of pores, and numerous abrasive particles held in the base material or the pores; The abrasive particles include specific particles that have a chemical mechanical abrasive effect on amorphous, crystalline or amorphous-crystalline composite solids. The slurry contains a pore-forming agent capable of forming numerous large pores that communicate with the plurality of fine pores and have a volume larger than that of each of the fine pores in the third step.

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