Carrier and substrate manufacturing method using this carrier

[0052] [the first embodiment]

[0053] figure 1 It is a figure which shows the cross section of the main part of the double-side polishing apparatus used when polishing the surface of the board|substrate of this embodiment. In addition, in this embodiment, only the double-sided grinding device is described, but it is not limited thereto. For example, the grinding pad provided on the platen is changed to a grinding pad, and it can also be used as a double-sided grinding device having the same function. .

[0054] As the substrate (to-be-processed object), for example, an annular or square plate-shaped substrate can be used. Specific examples of these substrates include substrates for magnetic disks such as substrates made of glass or aluminum alloys, aluminum alloy substrates with a NiP alloy coating film formed on the surface, rectangular glass substrates for liquid crystal panels, and glass for screen protection. cover, photomask base, silicon wafer, etc., but the material, shape, size, etc. of the substrate are not limited thereto. In addition, the present invention is particularly suitable for processing a substrate for a magnetic disk from the viewpoint that both surfaces of the substrate need to have low roughness and low defects, and that a plurality of substrates can be processed at one time with high quality. Next, as an example, the case where the glass substrate for magnetic discs is used as a to-be-processed object is demonstrated.

[0055] The double-sided polishing apparatus 100 is an apparatus for polishing the upper and lower surfaces of a glass substrate 102 , and includes a carrier mounting portion 106 to which a carrier 104 is mounted, an upper platen 108 , and a lower platen 110 . The carrier mounting unit 106 has an internal gear 112 and a sun gear 114 that are rotationally driven at predetermined rotation ratios, and mounts the carrier 104 .

[0056] The carrier 104 has a gear portion 115 formed on its outer periphery, and is attached to the carrier attachment portion 106 such that the gear portion 115 meshes with the internal gear 112 and the sun gear 114 . The carrier 104 performs planetary gear motion in a state attached to the carrier mounting portion 106 , and revolves while rotating around the sun gear 114 .

[0057] The upper platen 108 and the lower platen 110 are driven in opposite directions with the carrier mounting portion 106 interposed therebetween. In addition, polishing pads 116 and 118 are attached to the surfaces of the upper platen 108 and the lower platen 110 facing the glass substrate 102 , respectively. The upper platen 108 is movable in the vertical direction, and pressurizes the polishing pads 116 , 118 above and below the glass substrate 102 . In addition, as the polishing pads 116 and 118, foams of synthetic resins such as polyurethane and polyester are used.

[0058] Then, a slurry (polishing liquid) containing abrasive grains is supplied from above the carrier 104 through a supply pipe 120 provided on the upper platen 108 . Thus, in the double-sided polishing device 100 , while the polishing liquid is being supplied, the carrier 104 performs planetary gear movement, and the upper platen 108 and the lower platen 110 rotate in reverse with each other. Therefore, in the double-sided polishing apparatus 100, the glass substrate 102 and the polishing pads 116, 118 are relatively moved, and the upper and lower main surfaces of the glass substrate 102 are polished.

[0059] The carrier 104 has one or more holding holes 122 . Carrier 104 holds one or more glass substrates 102 that are sandwiched and polished between polishing pad 116 of upper platen 108 and polishing pad 118 of lower platen 110 through holding holes 122 . In addition, in the double-sided polishing apparatus 100 , after polishing the main surfaces of the upper and lower surfaces of the glass substrate 102 , the upper platen 108 is raised to take out the polished glass substrate 102 from the carrier 104 .

[0060] Here, the carrier 104 is used for polishing, but is not limited thereto, and can be widely used for main surface grinding other than polishing, such as friction using free abrasives and grinding using a grinding pad with fixed abrasives. In addition, the carrier 104 may be of a type in which the carrier main body portion having the holding hole 122 and the gear portion 115 are separate members, and both are used in combination when used.

[0061] figure 2 is zoomed in figure 1 A schematic diagram of a portion of the upper surface of the carrier 104. figure 2 (a) is an enlarged top view showing a part of the upper surface 124 of the carrier 104 . figure 2 (b) is figure 2 A-A section view of (a).

[0062] like figure 2As shown in (a), a plurality of protrusions 136 exist on the upper surface 124 of the carrier 104 . The main component of the plurality of protrusions 136 is glass. The surfaces other than the protrusions are, for example, resin. As the resin, for example, epoxy resin, polyvinyl chloride, polycarbonate, phenol, polyacetal copolymer, polyethylene terephthalate and the like can be used. Among them, epoxy resin is particularly preferable because it can improve bending strength and elastic modulus when impregnated with glass fibers, and has high water resistance and chemical resistance.

[0063] Further, when the carrier 104 is made of a material obtained by weaving glass fibers and impregnating them with resin, details will be described later, but fibrous glass may be included, and may be arranged approximately regularly in a grid or the like. In addition, the protrusion 136 is in figure 2 In (b), it is formed only on the upper surface 124 of the carrier 104 and is not provided on the lower surface 135 , but it may be provided on both upper and lower surfaces as long as the effect of suppressing adsorption to the upper platen 108 side is not hindered. When the protrusions 136 are provided on both upper and lower surfaces, the height and number of the protrusions 136, the area where the protrusions 136 are formed (protrusion forming area), and the like may be appropriately adjusted on the respective surfaces.

[0064] For such as figure 2 The protrusions 136 shown in (b) preferably each have a height dimension La of 2 to 50 μm and a width dimension Lb of 50 to 600 μm, for example. In addition, the width dimension Lb is the longest length in the direction of the main surface 134 of the carrier 104 .

[0065] The protrusion 136 has an upwardly protruding circular arc shape. figure 2 In (b), it is in the shape of a mountain. However, as a whole, as long as it is an arc shape that protrudes upward, it is not limited thereto, and it may be formed in a shape that becomes smaller toward the upper part. The shape in which the cross-sectional area of ​​the plane parallel to the main surface 134 becomes smaller. In addition, for example, an ellipse or an upwardly convex hemispherical shape may also be used. With such a shape, the protrusion 136 does not have an angle of about 90 degrees at the top 136A, but has a circular shape.

[0066] In addition, when the carrier 104 is made of a material obtained by weaving glass fibers and impregnating resin, it is also possible to make the glass fibers in the mesh of the glass fibers by implementing the manufacturing method of the carrier 104 of this embodiment described later. The protrusions 136 are formed by raising the fibers, or the protrusions 136 are formed by cutting a part of the glass fibers in a raised state. That is, a plurality of protrusions 136 of glass material may be formed substantially regularly on the upper surface 124 of the carrier 104 . Compared with the protrusions made of resin, the protrusions 136 made of glass have higher wear resistance, and are less likely to be worn even if the polishing process is repeated.

[0067] Regarding the above, in other words, the protrusions 136 of the glass material may be formed by exposing or exposing a part of the glass fibers contained in the carrier on the outermost surface. In addition, the exposed or exposed glass fibers may include chopped glass fibers.

[0068] The aforementioned protrusions 136 do not necessarily need to be formed on the entire surface of the main surface of the carrier. The protrusions 136 mainly composed of glass in the present invention have a very high anti-sticking effect, and therefore sufficient effects can be exhibited as long as the protrusions 136 are formed on at least a part of the main surface. In this specification, the region where the above-mentioned protrusion 136 is formed is also referred to as a "protrusion forming region". When the above-mentioned protrusion forming region is provided on a part of the main surface of the carrier, it may be divided into a plurality of regions and formed.

[0069] In addition, it is preferable that the area occupied by the above-mentioned protrusion-forming region (when there are a plurality of protrusion-forming regions, the total) is 10% or more of the area of ​​at least one entire surface of one of the carriers where the protrusion-forming region is present. . When the area ratio of the protrusion-forming region is less than 10%, the effect of preventing sticking in the final stage of long-term continuous processing may decrease due to adhesion of abrasives and the like to the carrier surface. More preferably, the proportion of the above-mentioned area is 20% or more. In addition, when the ratio of the above-mentioned area is small, the effect of preventing sticking can be enhanced even with a small area by forming protrusions centered on the vicinity of the outer periphery of the carrier.

[0070] In addition, it is preferable that the respective areas of the above-mentioned protrusion forming regions are 1 cm 2 above. When the area is less than 1cm 2 In some cases, the effect of preventing adhesion may not be sufficiently obtained. In addition, it is more preferable that the respective areas of the protrusion forming regions are 2 cm 2 above. On the other hand, from the viewpoint of the effect of preventing sticking, the upper limit of the above-mentioned area is not particularly specified. However, if the above-mentioned area is too large, operations such as masks for avoiding the holding holes are required, and the productivity of the carrier may deteriorate, so 400 cm is more preferable. 2 the following. In addition, when there are a plurality of protrusion forming regions, it may be smaller than 1/2 of the whole, and may be less than 1 cm 2. More preferably less than 1cm 2 The number of protrusion-forming regions is less than 1/3 of the total number, and it is further preferred that there is none. When less than 1cm 2 When the number of protrusion-forming regions is 1/2 or more of the total number of regions, it may be difficult to perform a protrusion-forming operation using a mask or the like, and the productivity of the carrier may deteriorate.

[0071] In addition, in the above-mentioned protrusion forming region, it is preferable that every 1 mm 2 There is a density of 0.5 or more to form protrusions. By setting the number to more than 0.5, the effect of suppressing the adhesion of the carrier to the platen can be reliably obtained. Further preferably every 1mm 2 One or more protrusions are formed. On the other hand, for this density, from the viewpoint of the effect of suppressing the sticking, no upper limit is particularly set, but from the viewpoint of the polishing pad or grinding pad provided on the surface of the platen (in this specification, these are collectively referred to as From the viewpoint of damage to "processing pad"), it is more preferable that every 1mm 2 Form 10 or less protrusions. If damage to these processing pads occurs, when substrate manufacturing based on long-term continuous processing is performed, the difference between the surface and the back surface may become large at the final stage of manufacturing. The density of the protrusions may be obtained by observing a plurality of protrusion-formed regions using a scanning electron microscope (hereinafter, abbreviated as SEM), for example, and obtaining an average value.

[0072] For example, the carrier 104 of the present invention can be produced by the following method. For example, in the case of a carrier made of braided glass fibers impregnated with resin, by chemical or mechanical means (see image 3 ) removes the resin or glass which is the constituent material of the carrier to expose a part of the glass fibers located close to the surface of the carrier. In addition, even when any method is used, it is possible to form the protrusions 136 in any region on the surface of the carrier 104 by appropriately combining it with a masking process when manufacturing the carrier 104 .

[0073] As a chemical method, for example, a method such as dissolution or etching can be used. In these methods, it is only necessary to appropriately select a substance capable of dissolving or etching and bring resin or glass into contact therewith. In addition, a substance capable of dissolving or etching both resin and glass may also be used.

[0074] image 3 (a) is a diagram showing an example of manufacturing the carrier 104 of this embodiment using a chemical method. Here, an etchant 138 for dissolving the resin is applied to a region 126 (protrusion formation region) indicated by oblique lines in the drawing on the upper surface 124 of the carrier 104 . As the etchant 138, a liquid or paste etchant may be appropriately selected.

[0075] The region 126 may be the entire upper surface 124 of the carrier 104 or a part thereof as long as the above-mentioned protrusion 136 can be formed. exist image 3 In the figure, as the region 126 , a region located outside the periphery 130 of the three holding holes 122a, 122b, and 122c of the upper surface 124 of the carrier 104 and surrounded by these holding holes 122a, 122b, and 122c is exemplified. In addition, when the carrier 104 is manufactured, the above-mentioned chemical method or mechanical method can be applied to only a part of the surface of the carrier 104 by appropriately performing a mask.

[0076] When the protrusion 136 is formed on a part of the surface of the carrier 104, as described above, it is preferably formed in the region 126 surrounded by at least three or more holding holes 122a, 122b, and 122c. If the region where the protrusion 136 is formed is provided between the two holding holes, the manufacturing cost and time of the carrier 104 may increase.

[0077] In addition, it is preferable that the protrusion 136 is formed at a position other than the peripheral edge 130 , avoiding a predetermined width around the holding hole 122 , for example. Assuming that the protrusion 136 is formed to the contour of the holding hole 122 , there are cases where damage occurs on the inner wall surface of the holding hole 122 or the shape of the holding hole 122 is changed. In this case, free movement of the substrate during the polishing process may be hindered, uniform polishing of the main surface of the substrate may be hindered, or damage may occur on the end surface of the substrate. In addition, the predetermined width is, for example, preferably 1 mm or more, more preferably 2 mm or more, from the viewpoint of working efficiency.

[0078] In addition, it is preferable to set the region 126 where the protrusion 136 is provided as a plurality of regions separated from each other. Thus, when a plurality of holding holes 122 are provided in order to improve manufacturing efficiency, and the space between the two holding holes 122 is very narrow, the area where the protrusion 136 exists can be avoided between the two holding holes 122, so that The manufacturing efficiency of the carrier 104 is improved.

[0079] In addition, a plurality of regions that are recesses of a predetermined depth may be formed on the surface of the carrier 104, and the protrusions 136 may be formed in the recesses. Thus, the possibility of contact between the protrusions 136 and the polishing pad is reduced, the durability of the protrusions 136 is further improved, dust generated by friction with the polishing pad can be suppressed, and the quality of the processed substrate surface can be further improved. In addition, for example, the depth of the concave portion may be 0.3 to 30 μm. In addition, on one surface of the carrier 104 , it is preferable that the total area of ​​all the regions where the recesses are formed is 5 to 80% of the area of ​​the entire surface of the carrier 104 .

[0080] In addition, if image 3 As shown in (b), a mechanical method of rubbing or grinding the surface of the carrier 104 may be performed using a grinding tool (grinding tool) such as sandpaper, a file, or a grinder. Here, a grinding tool 146 is attached to the front end 144 of the grinding machine 142 , and the surface of the region 126 is ground by making appropriate contact or the like.

[0081] In addition, in the case of the carrier 104 made of braided glass fibers impregnated with resin, since the hardness and physical properties of glass and resin are greatly different, by appropriately selecting the above-mentioned etchant 138 and abrasive tools, etc., , so that the removal object is set to one or both of resin and glass fiber.

[0082] In addition, it is also possible to combine the above-mentioned chemical methods and mechanical methods. For example, after the resin has been roughly removed mechanically, it is then chemically removed, enabling finishing with less burrs. In addition, if many burrs remain on the surface of the carrier, the polishing pad of the double-sided polishing apparatus 100 may be damaged, or the burrs may detach during processing and cause contamination of the substrate surface by foreign matter.

[0083] In addition to the above-mentioned method, the concave portion 128 may be formed by laminating a resin or metal film while masking the region 126 on the surface of the carrier where the concave portion 128 is to be formed, and then removing the mask.

[0084] Next, when the carrier 104 is made of braided glass fibers impregnated with resin, the process of forming the protrusions 136 by applying the chemical method or the mechanical method to the region 126 of the upper surface 124 of the carrier 104 will be described. Figure 4 is a schematic view of the upper surface 124 of the carrier 104 before the protrusions 136 are formed. Figure 5is a schematic view of the upper surface 124 of the carrier 104 after the protrusions 136 have been formed. In addition, in Figure 4 and Figure 5 , an enlarged view of a portion of region 126 is schematically illustrated.

[0085] Figure 4 The illustrated carrier 104 is an enlarged view of the surface of a sheet material in which glass fibers 150 are woven and impregnated with resin. This sheet is a fabric formed by forming fiber bundles of tens to hundreds of glass fibers 150 and alternately weaving them (herein, each resin-impregnated sheet is referred to as a pre-impregnated sheet). body) stack. It is a so-called plain weave in which longitudinal bundles and lateral bundles of glass fibers 150 are alternately exposed on the surface side for each mesh 152 . In addition, since the thickness of the prepreg is very thin, for example, 0.1 to 0.2 mm, the sheet is usually formed by laminating a plurality of prepregs and crimping the plurality of prepregs. Also, although not particularly shown in the drawings, the surface is covered with a resin layer.

[0086] In such a carrier 104 , the glass fiber 150 has the shape of a mountain in a protruding state on the surface layer side at the overlapping position of the mesh 152 . As an example, the longitudinal bundles or lateral bundles of the glass fibers 150 rise substantially regularly on the surface side so that every grid 152 undulates. The glass fibers 150 are usually buried in resin, so they appear almost flat in appearance, but when the resin on the surface disappears due to dissolution or the like, glass fiber bundles (or glass fibers) emerge in the shape of mountains. This is because the prepreg is pressed with a strong force when crimping the prepreg, and the resin is cured in this state. That is, stress to return to the original thickness is generated in the glass fiber bundle. With this configuration, the protrusions can be easily and substantially regularly formed by relieving the stress applied to the glass fibers.

[0087] Figure 5 (a) is a diagram schematically showing a state where the protrusions 136 are formed substantially regularly. For each cell 152 where the longitudinal bundles appear on the surface side, and each cell 152 where the horizontal bundles appear on the surface side, a raised portion 154 that emerges and rises in the shape of a mountain as a glass fiber bundle (or glass fiber) is formed. 136 of protrusions. Microscopically, the longitudinal glass fibers and the transverse glass fibers are not necessarily uniformly woven, so the thickness of the resin covering the surface may vary depending on individual differences in sheets or positions within one sheet. Figure 5 (a) is an example of this case.

[0088] So, for example, in Figure 5 In (a), protrusions 136 may be formed in all 9 grids 152 that can be confirmed, and protrusions 136 may be formed in only 5 grids 152 of longitudinal glass fibers. However, in any case, the protrusions 136 are formed substantially at the center of the grid 152, so the protrusions 136 can be formed substantially regularly. In other words, the protrusions 136 can be formed substantially regularly according to the grid 152 . In addition, if the protrusions are formed so as to straddle the boundary of the grid 152 , the area of ​​the resin covering the surface may decrease and the strength of the carrier 104 may decrease. In other words, it is preferable that the resin exists between protrusions and protrusions in the surface of the carrier.

[0089] In addition, when forming the protrusion 136, it is not necessarily necessary to remove the resin until the glass fiber 150 embedded in the resin is completely exposed. In the case of the carrier 104 made of braided glass fibers 150 impregnated with resin, the glass fibers 150 (or glass fiber bundles) are fixed by the resin while being compressed in the thickness direction in the manufacturing process. Therefore, by removing a part of the resin to such an extent that the stress applied to the glass fibers 150 is released, it is possible to form the protrusions 136 mainly composed of glass. In addition, when the glass fiber embedded in resin is non-fibrous glass, such as glass particle, the said content is the same. That is, it is not necessarily necessary to remove the resin until the glass embedded in the resin is completely exposed.

[0090] When the protrusions are formed in this way, the resin may remain on a part of the surface of the protrusions, but it is only necessary that the glass component is exposed on at least a part of the surface. Whether or not the glass component is exposed on the surface of the protrusion can be confirmed by, for example, SEM and energy dispersive X-ray analysis (hereinafter abbreviated as EDX).

[0091] In addition, on the surface of the carrier 104, when the resin covering the glass fiber 150 is relatively thin, a substance capable of dissolving and etching glass can be used. In this case, the glass dissolved substance permeates the resin layer and reaches the glass fiber 150 inside, and a part of the dissolved substance of the glass fiber 150 overcomes the coating of the resin and deposits on the surface. As a result, the coating of the resin is broken, so that a bump including the glass fiber 150 is formed.

[0092] Additionally, if Figure 5 As illustrated in (b), part of the glass fiber 150 constituting the protrusion 136 may be cut. If a part of the glass fiber 150 is cut, the fragments of the glass fiber 150 tend to protrude from the surface. In other words, the cut glass fibers 150 tend to stand up from the surface of the carrier 104 . Thereby, the cut glass fiber is contained in a part of the protrusion 136, and the above-mentioned adhesion effect can be enhanced. In addition, according to the research of the inventors, under the etching conditions using a general glass etching solution, only a part of the glass fiber is cut, so the rigidity of the glass fiber is low, and it is difficult to damage the opposing polishing pad or polishing pad. The reason is presumed that hundreds of glass fibers form a bundle, and resin exists between each glass fiber.

[0093] In addition to the above-mentioned methods, when using resin as a component of the carrier surface, fine particles mainly composed of glass with a predetermined particle size can be used to scatter on the carrier surface, and press while heating to bury a part of the glass particles. The protrusions are formed by a method of penetrating into the surface of the carrier, or a method of dispersing glass fine particles after applying an adhesive to the surface of the carrier.

[0094] After the protrusion 136 mainly composed of glass is formed by the method described above, cleaning treatment and deburring treatment may be appropriately performed. In addition, it is also possible to use a dresser such as a diamond dresser to adjust the height of the protrusions or perform a deburring process.

[0095] In addition, for example, the shape of the protrusion 136 of the completed carrier 104 can be confirmed by appropriately using a stylus-type or optical-type surface shape measuring device such as the height and length. In addition, by performing SEM observation and elemental analysis by EDX on the protrusions 136, for example, it is possible to confirm whether the protrusions 136 contain glass components, whether glass fibers are contained, and further confirm the presence or absence of cut glass fibers. In addition, a micrometer or a length gauge can be used to confirm the removal depth of the resin and the change in the thickness of the carrier 104 .

[0096] According to the carrier 104 of this embodiment, a plurality of protrusions 136 are present on the upper surface 124 of the carrier 104 , so that when the upper platen 108 is raised, air easily enters between the upper surface 124 of the carrier 104 and the upper polishing pad 116 . Therefore, it is possible to prevent the carrier 104 from sticking to the upper platen 108 . In addition, since the protrusion 136 is made of a glass material, the wear resistance is high, and the sticking of the upper platen 108 can be prevented more frequently.

[0097] In addition, by regularly disposing the protrusions 136, the air can easily enter between the upper surface 124 of the carrier 104 and the upper polishing pad 116, thereby preventing sticking more effectively.

[0098] In addition, the protrusion 136 can be formed in a smooth convex shape as a whole. In addition, it may not have a corner of about 90 degrees at the top 136A. In addition, since it has a circular shape as a whole, it is difficult to damage the polishing pad 116 in contact with the protrusion 136 . As a result, both surfaces of the glass substrate 102 can be equally polished even in a carrier having different specifications on the front and back.

[0099] It can be clearly known from the embodiments described next that the protrusion 136 will be as figure 2 Since the height dimension La shown in (b) is set to 2 μm or more (see Table 1), the wear resistance becomes high and sticking can be prevented more effectively. Also, for example, in the case of a sheet made of woven glass fibers and impregnated with resin, in addition to changing the amount of etching, the thickness of the glass fibers 150, the number of bundles, the weaving method, and the number of bundles can be appropriately set. The size (interval) of the grid, thereby adjusting the height and width of the protrusions 136 .

[0100] Also, for example, in the case of a sheet made of woven glass fibers and impregnated with resin, in addition to changing the amount of etching, the thickness of the glass fibers 150, the number of bundles, the weaving method, and the number of bundles can be appropriately set. The size (interval) of the grid, thereby adjusting the height and width of the protrusions 136 . For example, the height and width of the protrusions can be increased by increasing the amount of resin etched.

[0101] For the dimensional values ​​of the height and width of the above-mentioned protrusions 136 , when 100 protrusions are randomly sampled and measured, the average value of the first 50 values ​​with larger values ​​can be obtained. Through such calculations, it is possible to obtain the dimensions of the protrusions that contribute to the reliable prevention of the sticking of the upward pressure plate.

[0102] [Example]

[0103] Hereinafter, examples of the present invention will be described by way of example, but the present invention is not limited to the following examples.

[0104] (Preparation of substrate to be processed)

[0105] The substrate to be processed was set as a glass substrate for a magnetic disk with a nominal size of 2.5 (about 65 mm in diameter), and the following substrate was prepared by a known method. owned.

[0106] (Preparation of the carrier for the experiment)

[0107] The carrier was manufactured by shape-processing a sheet obtained by weaving glass fibers and impregnating epoxy resin. Then, using the method described above as appropriate, additional processing was performed on one surface of the carrier to form a plurality of protrusions having the specifications shown in Table 1. In addition, regarding other specifications, the width of the protrusions is set to 300 μm, and the density of the protrusions is set to 3 (pcs/mm 2 ), and the proportion of the area occupied by the protrusion-forming region on the main surface of the carrier was set to 50%. In addition, based on the confirmation result of SEM, the cut|disconnection of glass fiber was not recognized. Here, for the dimensional values ​​of the height and width of the protrusions, 100 protrusions are randomly sampled and measured, and the average value of the first 50 values ​​with larger values ​​is taken.

[0108] (experimental conditions)

[0109] In addition to the following, the above-mentioned second polishing for the substrate to be processed is performed using the above-mentioned or known methods. As the polishing machine, the above-mentioned double-sided polishing apparatus having polishing pads attached to the upper and lower platens was used to simultaneously polish both sides of the substrate to be processed. The polishing pad is a polishing pad made of polyurethane resin, and is a suede-type polishing pad having a fluff layer on the surface layer. The fluff layer is formed with a plurality of elongated fine pores ( fluff). The abrasive is a polishing liquid including colloidal silica particles having an average particle diameter (D50) of 30 nm as polishing abrasive grains. In addition, regarding the direction of the carrier, it is installed in the grinder so that the surface having the protrusion faces upward.

[0110] In addition, in one polishing process (one batch), five carriers were installed so that each carrier could hold 10 substrates, and both main surfaces of 50 substrates were polished at a time. While replacing the substrate to be processed, the carrier is not replaced, and 20 batches of continuous processing are performed. That is, in each experimental example, platen adhesion on a carrier was checked 100 times in total.

[0111]In addition, in each experimental example, using the board|substrate processed in the 20th batch, the difference of the minute waviness of the front surface and the back surface of a main surface was calculated|required. Specifically, two substrates were sampled from each carrier, that is, a total of 10 substrates were sampled, and the average value of the small fluctuations on the upper platen side (10 sides) and the average value of the lower platen side (10 sides) were calculated. ) and calculate the difference of these averages.

[0112] In Table 1, the case where there is no protrusion mainly composed of glass on the surface of the carrier is taken as a comparative example, and the cases where there are protrusions and the heights of the protrusions are different are taken as Examples 1 to 8. In addition, the ratio of the number of occurrences of sticking in Table 1 means the relative value when the comparative example was set to "1.0".

[0113] [Table 1]

[0114]

[0115] As shown in Table 1, only when the 2 μm protrusions were formed on the surface of the carrier, a high effect of preventing sticking was obtained. In addition, if the height of the protrusions is 3 μm or more (Examples 2 to 8), it is possible to substantially eliminate the sticking of the carrier to the platen. On the other hand, when the height of the protrusions exceeds 50 μm (Example 8), the difference between the front and rear surfaces in the processed substrate surface shape is slightly larger than that of other Examples. Therefore, the height of the protrusions is preferably 50 μm or less. In Example 8, since the height of the protrusions was too high, it is presumed that the surface of the polishing pad on the opposing upper platen side was damaged and the surface was roughened. From this, it was confirmed from the results in Table 1 that the height of the protrusions is preferably 2 to 50 μm.

[0116] In addition, the minute fluctuations in Table 1 were measured using a laser-based optical surface shape measuring device. The measurement method is as follows. Laser light of a predetermined wavelength is incident on the surface of the measurement object at a predetermined angle, and the reflected light from the measurement object is detected to obtain height information of the main surface. The wave band of minute fluctuations is 10-500 μm. In this embodiment, the front and back surfaces of a glass substrate with a diameter of approximately 65 mm are measured using the range of 15 mm to 30 mm in radius from the main surface as the measurement area, and the "difference" of minute fluctuations between the front and back surfaces is calculated. When the processing quality is required to be the same on both sides as in a substrate for a magnetic disk, if the difference becomes large, the polishing of the main surface with larger micro-fluctuations will be poor, and regrinding, etc., will be required. Sexual deterioration, so it is not preferred.

[0117] In addition, regarding Example 8, it was confirmed that the difference between the first batch and the tenth batch had the same slight fluctuation, and the result was 0.001 or less, which was a good result. From this, it was confirmed that the difference in minute fluctuations occurs when long-term continuous processing is performed.

[0118] Therefore, according to the manufacturing method of the carrier 104 and the glass substrate 102 using the carrier 104 of the present embodiment, the plurality of protrusions 136 present on the upper surface 124 of the carrier 104 prevent the carrier 104 from sticking to the upper platen 108, thereby preventing the glass from The difference of minute fluctuations between the upper surface and the lower surface of the substrate 102 becomes large, so that a high-quality glass substrate 102 can be obtained.

[0119] Next, based on the conditions of Example 5, the etching amount of the epoxy resin in the sheet material which is the primary material of the carrier 104 was appropriately changed to manufacture the carrier 104 in which the width dimension of the protrusion 136 was changed. Thereafter, the surface was processed by a grinder so that the height of the protrusions 136 was uniformly 20 μm. Using these carriers 104, 100 batches of continuous processing were performed in the same manner as above. Table 2 summarizes their results.

[0120] [Table 2]

[0121]

[0122] From Examples 10 to 14, it was confirmed that by setting the width of the protrusion 136 to 50 μm or more, the effect of suppressing sticking was maintained for a long period of time. On the other hand, regarding Example 14 in which the width of the protrusions was 900 μm, abnormal noise was detected during processing. Therefore, it can be confirmed that from the viewpoint of suppressing abnormal noise, it is preferable to set the thickness to 600 μm or less.

[0123] (relationship with protrusion density)

[0124] Based on the conditions of Example 5, the density of the protrusions (pieces/mm 2 ) was changed to 0.5, 1, 5, and 10 carriers, and 20 batches of substrates were continuously polished. Table 3 shows the experimental results. From Examples 15 to 18, it can be seen that none of the carriers adhered to the upper platen.

[0125] [table 3]

[0126]

[0127] (Relationship with the area ratio of the protrusion formation region)

[0128] Based on the conditions of Example 5, carriers were prepared in which the ratio (%) of the area of ​​the protrusion-forming region was changed to 10, 20, 75, and 100, and 20 batches of continuous polishing of the substrate were performed. Table 4 shows the experimental results. From Examples 19 to 22, it can be seen that up to the 20th batch, there was no adhesion of the carrier to the platen.

[0129] [Table 4]

[0130]

[0131] (relationship with cut glass fiber)

[0132] Based on the carrier produced under the conditions of Example 1, the surface was treated with a liquid containing fluosilicic acid, and then the surface was treated with a grinder. In this way, glass fibers were protruded from the surface of the carrier, and a part thereof was cut to prepare a carrier having the same average height of the protrusions as in Example 1. Using this carrier, 20 batches of continuous polishing of the substrate were performed. As a result, the ratio of the number of sticking occurrences was 0.1, which was halved. In addition, in the same manner as above, the carrier produced under the conditions of Example 9 was treated, and no sticking was detected in more than 100 batches after the continuous grinding treatment experiment. From these results, it can be confirmed that by cutting a part of the glass fiber, a higher anti-adhesion effect is further obtained.

[0133] (relationship with concave part)

[0134] In the carrier of Example 8, three types of carriers were prepared in which the resin in the protrusion formation region was etched and the recesses were 0.3, 10, and 30 μm in depth. Using these carriers, 20 batches of continuous polishing processes for substrates were performed. In the same manner as above, for the substrates processed in the 20th batch, the difference between the micro-waviness of the front surface and the back surface of the main surface was evaluated and found to be 0.0017, 0.0012, and 0.001 or less, respectively. In addition, no sticking occurred. From this result, it was confirmed that the difference between the fine waviness of the front and back can be reduced by forming protrusions in the concave portion.

[0135] [the second embodiment]

[0136] A second embodiment of the carrier of the present invention and a method of manufacturing a substrate using the carrier will be described. The parts that overlap with the description of the above-mentioned first embodiment are given the same reference numerals and the description thereof will be omitted.

[0137] Image 6 is showing figure 1 A top view of the carrier 104. On the upper surface 124 of the carrier 104 representatively shown in the figure, recesses 128 are provided in a plurality of regions 126 (protrusion forming regions) (refer to Figure 7 (b)). As shown, the plurality of regions 126 are located outside the perimeter 130 of the retaining aperture 122 and are spaced apart from one another. In particular, it may be a region surrounded by at least three holding holes 122 and not continuous with the holding holes 122 .

[0138] In addition, the contour forming the plurality of concave portions 128 is formed of a free curve, for example, formed so as not to contact the gear portion 115 formed on the outer periphery of the carrier 104 . In addition, the area occupied by the entirety of the plurality of recesses 128 is 5% or more of the entire area of ​​the upper surface 124 of the carrier 104, and the upper limit is set at 80% or less. In addition, the area of ​​the plurality of recesses 128 is set to 1 cm 2 Above and 400cm 2 the following range. Preferably, the number of recesses 128 having an area satisfying this range is 1/3 or more of all recesses 128 . More preferably, it is 1/2 or more, and it is still more preferable that it is all. In addition, when it is less than 1/3, the effect of suppressing adhesion may not be stably obtained.

[0139] Figure 7 is shown set in Image 6 A schematic diagram of the recess 128 and its surroundings on the upper surface 124 of the carrier 104 . Figure 7 (a) is a schematic diagram representatively showing the region 126 located on the upper surface 124 of the carrier 104 . Figure 7 (b) is Figure 7 A-A section view of (a).

[0140] Figure 7 The region 126 shown in (a) includes a region surrounded by the three holding holes 122a, 122b, and 122c, and is not continuous with these holding holes 122a, 122b, and 122c. like Figure 7 As shown in (b), a concave portion 128 is provided in the region 126 . The entire circumference 132 of the recess 128 forms a main surface 134 of the carrier 104 . That is, the concave portion 128 is shaped like a pool or a bag, and can store polishing liquid. Additionally, if Figure 7 As shown in (b), the recess 128 is provided only on the upper surface 124 of the carrier 104 and not on the lower surface 135, but it may be provided on both upper and lower surfaces as long as the effect of suppressing adsorption to the upper platen 108 side is not hindered. When the concave portion 128 is set on the upper and lower sides, it is only necessary to properly adjust the area and number of the concave portion 128 and the depth dimension Lc in each surface (see Figure 8 (b)), the region where the concave portion 128 is formed, and the like are sufficient.

[0141] Figure 8 is zoomed in Figure 7 Schematic diagram of region B of (a). Figure 8 (a) is an enlarged plan view showing the B region. Figure 8 (b) is Figure 8 C-C section view of (a). like Figure 8 As shown in (a), the concave portion 128 is provided in the region 126 outside the peripheral edge 130 of the holding hole 122 . also, Figure 8 The depth dimension Lc of the concave portion 128 shown in (b) is set to 0.3 to 30 μm.

[0142] According to the carrier 104 of the present embodiment, by forming the recess 128 in the region 126 on the upper surface 124 of the carrier 104 , the polishing liquid can be stored in the recess 128 . As a result, even when the carrier 104 tries to be in close contact with the polishing pad 116 of the upper platen 108 , the close contact area of ​​the resins on the surfaces of each other can be reduced. Therefore, the adsorption force of the surface of the carrier 104 to the polishing pad 116 is reduced, and the effect of preventing sticking (adsorption) is high.

[0143] In addition, the contour of the concave portion 128 formed in the region 126 is composed of a free curve, and is preferably formed so as not to contact the gear portion 115 of the carrier 105 . Therefore, when the surface of the glass substrate 102 is polished, the polishing liquid can be reliably stored in the concave portion 128 , so the effect of preventing sticking is high.

[0144]In addition, the area occupied by the plurality of recesses 128 as a whole is preferably not less than 5% and not more than 80% of the area of ​​the entire surface of the carrier 104 . If the ratio of the total area of ​​the recesses 128 is less than 5%, the effect of preventing sticking may not be stably obtained for a long time due to the adhesion of abrasives and the like to the surface of the carrier 104 . On the other hand, if the ratio of the total area of ​​the recesses 128 is too large, the carrier 104 may be warped, and the glass substrate 102 as a substrate to be polished may be detached from the carrier 104 . Therefore, the upper limit of the ratio of the area is preferably 80% or less. In addition, when the ratio of the above-mentioned area is small, the recesses are distributed around the periphery of the carrier, and the effect of preventing sticking can be enhanced even with a small area.

[0145] In addition, it is preferable that the area of ​​at least 1/3 or more of all the recesses 128 is 1 cm. 2 Above and 400cm 2 the following. Assuming that the area of ​​the recess 128 is less than 1 cm 2 , the effect of preventing adhesion may not be sufficiently obtained. In addition, it is further preferable that the area of ​​the concave portion 128 is 2 cm 2 above. On the other hand, if the area of ​​the concave portion 128 is too large, the carrier 104 may be warped, and the glass substrate 102 may detach from the carrier 104 . Therefore, it is preferable that the upper limit of the area of ​​the concave portion 128 is 400 cm. 2 the following.

[0146] Additionally, the Figure 8 The depth dimension Lc of the concave portion 128 shown in (b) is set to 0.3-30 μm (see Table 1), so the polishing liquid can be sufficiently stored in the concave portion 128 . Therefore, adhesion of the carrier 104 can be prevented, and warping of the carrier 104 and detachment of the glass substrate 102 from the carrier 104 during the polishing process can be prevented.

[0147] [Example]

[0148] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples.

[0149] (Preparation of substrate to be processed)

[0150] The substrate to be processed was set as a glass substrate for a magnetic disk with a nominal size of 2.5 (about 65 mm in diameter), and the following substrate was prepared by a known method. owned.

[0151] (Preparation of the carrier for the experiment)

[0152] The carrier was manufactured by shape-processing a sheet obtained by weaving glass fibers and impregnating epoxy resin. Then, using the method described above as appropriate, one surface of the carrier was additionally processed to form a plurality of concave portions having the specifications shown in Table 1.

[0153] (experimental conditions)

[0154] The second polishing for the above-mentioned substrate to be processed is performed using the above-mentioned or known methods except for the following. As the polishing machine, the above-mentioned double-sided polishing apparatus having polishing pads attached to the upper and lower platens was used to simultaneously polish both sides of the substrate to be processed. The polishing pad is a polishing pad made of polyurethane resin, and is a suede-type polishing pad having naps on the surface layer, and the nap layer is formed with a plurality of elongated fine pores (pile) formed in the thickness direction by a foaming agent. . The abrasive is a polishing liquid containing colloidal silica particles having an average particle diameter (D50) of 30 nm as polishing abrasive grains. In addition, regarding the orientation of the carrier, it is installed in the grinder so that the surface having the concave portion faces upward.

[0155] In addition, in one polishing process (one batch), five carriers were installed so that each carrier could hold 10 substrates, and both main surfaces of 50 substrates were polished at a time. While replacing the substrate to be processed, the carrier is not replaced, and 20 batches of continuous processing are performed. That is, in each experimental example, platen adhesion on a carrier was checked 100 times in total.

[0156] In Table 3, the case where there are no recesses on the surface of the carrier is referred to as Comparative Example 2, and the cases where recesses are present and the depths of the recesses are different are referred to as Examples 15 to 21. In addition, the ratio of the number of occurrences of sticking in Table 3 is a relative value when Comparative Example 2 was set to "1.0". In addition, the concave portion of each embodiment is formed so as not to contact the gear portion of the carrier. In addition, for the recesses in each embodiment, the ratio of the area occupied by the entire surface of one surface of the carrier except the holding hole is set to 30%, and the area of ​​all the recesses is set to 1 cm. 2 above.

[0157] In addition, the deformation of the carrier in Table 3 refers to the result of unloading the carrier from the double-sided polishing device after the completion of 100 batches, and observing the warpage, deformation, and surface state. In addition, if there is deformation such as warping of the carrier, the substrate may be detached from the holding hole during the polishing process if the carrier is continuously used, which is not preferable.

[0158] [table 5]

[0159]

[0160] As shown in Table 5, first, when the depth of the concave portion is 0.3 μm or more (Examples 23 to 29), the ratio of the number of occurrences of sticking can be reduced, which is preferable. On the other hand, when the depth of the concave portion exceeded 30 μm (Example 29), warping of the carrier was confirmed. Therefore, the depth of the concave portion is preferably 30 μm or less. Thus, from the results in Table 5, it was confirmed that the depth of the concave portion is preferably 0.3 to 30 μm.

[0161] Therefore, according to the manufacturing method of the carrier 104 and the glass substrate 102 using the carrier 104 of this embodiment, sticking (adsorption) can be prevented by the plurality of recesses 128 provided in the region 126 of the upper surface 124 of the carrier 104 . In addition, since the carrier 104 is prevented from warping and the glass substrate 102 is detached from the carrier 104 during the polishing process, high-quality glass substrate 102 can be obtained at a higher yield than conventional ones without lowering productivity.