JP2019136784A - Both-side grinding device - Google Patents

Abstract

To provide a both-side grinding device that can improve flatness and parallelism of both sides of an object to be ground.SOLUTION: A both-side grinding device 1 comprises: a lower grindstone 10 which rotates with a first center Shaft C1 as a rotation shaft and in which a first grindstone surface 11 having an outer periphery with a first radius R1 from the first center shaft C1 is provided to face upward; and an upper grindstone 20 which rotates with a second center shaft C2 parallel to the first center shaft C1 as a rotation shaft and in which a second grindstone surface 21 having an outer periphery with a second radius R2 from the second center shaft C2 is provided to face downward. An object 50 to be ground is arranged in a grinding area, an area where the first grindstone surface 11 and the second grindstone surface 21 are opposed to each other. When a direction which is orthogonal to the first center shaft C1 and the second center shaft C2 and in which the first center shaft C1 is joined to the center shaft C2 is defined as a pitch direction, a length in the pitch direction of the grinding area is equal to the first radius R1 or less and to the second radius R2 or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a double-side grinding apparatus, for example, a double-side grinding apparatus that grinds both sides of a wafer.

  Patent Documents 1 to 5 disclose a double-side grinding apparatus that performs double-side grinding of a wafer with upper and lower grindstones provided above and below the wafer when grinding the wafer.

JP 2003-048156 A Japanese Patent Laid-Open No. 03-117560 JP-A-10-235556 Japanese Patent Laid-Open No. 2005-205585 JP 2004-148425 A

  For example, in a double-sided finishing process of a wafer, which is a material such as a semiconductor element, in single-side grinding by a single-side grinding device, spring back occurs when the suction force of a vacuum chuck that sucks the wafer is released, and both sides of the wafer are flat and parallel. May be difficult to maintain.

  As shown in FIG. 17, the single-side grinding device 171 grinds the reference surface of the wafer 173 disposed on the turntable 172 with a grinding wheel 175 including a grindstone chip 174. First, as shown in FIG. 18A, the wafer 173 is set on the turntable 172. Next, as shown in FIG. 18B, the wafer 173 is attracted to the turntable 172 provided with a vacuum chuck or the like. Thereafter, as shown in FIG. 18C, the reference surface of the wafer 173 is ground by a grinding wheel 175 including a grindstone chip 174. After grinding, the suction force of the wafer 173 to the turntable 172 is released. In this case, as shown in FIG. 18 (d), a spring back is generated and curved toward the reference plane side. The one-side grinding device 171 requires a machining allowance more than necessary and deteriorates the material yield. Therefore, it is desirable to grind the wafer by a double-sided processing process that does not require an attractive force.

  As shown in FIG. 19, a double-sided lapping device 191 that performs a double-sided processing step that does not require an adsorption force includes an upper surface plate 192, a lower surface plate 193, a carrier 195 that holds a wafer 194, a sun gear 196, and an internal gear 197. ing. This is a free abrasive grain method in which a wafer 194 is sandwiched between metal upper and lower surface plates, and an abrasive liquid 198 is poured into the gap to be processed. For this reason, in particular, in order to process ultra-high hardness such as silicon carbide (SiC), it takes a very long time (100 times slower) than processing of a material that is relatively easy to process such as silicon (Si). Therefore, a fixed-abrasive double-side grinding apparatus that allows a realistic processing rate in consideration of production tact is used depending on the material.

  As shown in FIGS. 20A to 20D, a fixed abrasive double-side grinding apparatus 201 is provided with an upper grindstone 220 and a lower grindstone 210 on upper and lower surface plates. First, as shown in FIG. 20A, the wafer 240 is held on the thin carrier 230. Next, as shown in FIG. 20B, the carrier 230 holding the wafer 240 is disposed between the upper grindstone 220 and the lower grindstone 210. Then, as shown in FIG. 20C, the carrier 230 holding the wafer 240 is rotated between the sun gear and the internal gear. After grinding, the carrier 230 is released as shown in FIG.

  The double-side grinding apparatus 201 is considered to be capable of high-rate and sufficiently high precision (parallelism and surface roughness) by simultaneously processing both surfaces of the wafer 240. However, in the double-side grinding apparatus 201, the grindstone surface is worn by grinding, and deviation from a predetermined shape occurs.

  As in Patent Documents 1 to 5, in a double-sided grinding apparatus where the area where the upper and lower grinding wheels overlap is large in the direction of gravity, a sufficient area for dressing the upper and lower grinding stones (sharpening of the grinding stone) during processing is sufficiently secured. Since it cannot be performed, the wear condition of the upper grindstone and the lower grindstone changes. As a result, the wear condition of the upper grindstone and the lower grindstone varies, and there is a possibility that the ground object cannot be ground flat.

  The present invention has been made to solve such a problem, and provides a double-side grinding apparatus capable of improving the flatness and parallelism of both surfaces of a ground product.

  A double-side grinding apparatus according to an aspect of the present invention is provided so that a first grindstone surface that rotates around a first central axis as a rotation axis and has an outer periphery with a first radius from the first central axis faces upward. A lower grindstone and a second central axis parallel to the first central axis are rotated as rotation axes, and a second grindstone surface having an outer periphery of a second radius from the second central axis is provided to face downward. A grinding object is disposed in a grinding region that is a region where the first grindstone surface and the second grindstone surface are opposed to each other, and is orthogonal to the first central axis and the second central axis, When the direction connecting the first central axis and the second central axis is the pitch direction, the length of the grinding region in the pitch direction is not more than the first radius and not more than the second radius. is there. With such a configuration, it is possible to suppress variation in the wear condition of the upper grindstone and the lower grindstone, and to improve the flatness and parallelism of both surfaces of the ground material.

  In addition, a sun gear and a counter gear that rotate a carrier gear that holds the grinding object in a plane parallel to the first grindstone surface, the sun gear is disposed outside the upper grindstone when viewed from above. The counter gear is disposed in an inner hole coaxial with the second central axis provided in the upper grindstone. With such a configuration, it is possible to process a ground object without interfering with the upper grindstone.

  According to the present invention, there is provided a double-sided grinding apparatus capable of improving the flatness and parallelism of both sides of a ground product.

1 is a perspective view illustrating a main part of a double-side grinding apparatus according to Embodiment 1. FIG. It is the perspective view which illustrated the state at the time of processing of the double-sided grinding device concerning Embodiment 1. 2 is a cross-sectional view illustrating a lower grindstone and an upper grindstone of a double-side grinding apparatus according to Embodiment 1. FIG. (A)-(d) is sectional drawing which illustrated the positional relationship of a lower grindstone and an upper grindstone. It is the perspective view which illustrated the double-sided grinding device which made the lower whetstone and the upper whetstone the coaxial structure. (A)-(c) is the figure which illustrated the displacement of a lower whetstone and an upper whetstone in the double-sided grinding apparatus which used the lower whetstone and the upper whetstone as the coaxial rotation structure, (a) is a load of 100 [N ], (B) has a load of 500 [N], and (c) has a load of 1000 [N]. (A)-(c) is the figure which illustrated the displacement of the lower grindstone and the upper grindstone in the double-sided grinding apparatus which concerns on Embodiment 1, (a) is a load of 100 [N], (b) The load is 500 [N], (c) is 1000 [N]. In the double-side grinding apparatus which concerns on Embodiment 1, it is a cross-sectional perspective view which illustrated the rotation drive mechanism of the carrier gear. In the double-sided grinding apparatus which concerns on Embodiment 1, it is sectional drawing which illustrated the rotation drive mechanism of the carrier gear. In the double-side grinding apparatus which concerns on Embodiment 1, it is explanatory drawing which illustrated the rotation drive mechanism of the carrier gear. (A) is the figure which illustrated the processing line of the surface of a grinding | polishing thing in the double-sided grinding apparatus which does not rotate a grinding | polishing thing, (b) is the figure of the surface of a grinding | polishing thing in the double-sided grinding apparatus 1 which concerns on Embodiment 1. FIG. It is the figure which illustrated the processing eyes. (A)-(d) is the figure which illustrated the truing technique of the lower whetstone and the upper whetstone in the double-sided grinding apparatus which concerns on the comparative example 1, (a) And (d) shows a cross-sectional perspective view, b) and (c) show schematic views. (A)-(c) is the figure which illustrated the truing technique of the lower whetstone and the upper whetstone in the double-sided grinding apparatus which concerns on Embodiment 2, (a) and (c) show a cross-sectional perspective view, b) shows a schematic diagram. (A) And (b) is the cross-sectional perspective view which illustrated the truing technique of the lower grindstone and the upper grindstone in the double-sided grinding apparatus which concerns on the comparative example 2. FIG. (A) And (b) is the cross-sectional perspective view which illustrated the truing technique of the lower grindstone and the upper grindstone in the double-sided grinding apparatus which concerns on the comparative example 3. FIG. (A) And (b) is the cross-sectional perspective view which illustrated the truing technique of the lower grindstone and the upper grindstone in the double-sided grinding apparatus which concerns on the comparative example 4. FIG. It is the perspective view which illustrated the single-sided grinding device. (A)-(d) is the figure which illustrated the grinding process in a single-sided grinding apparatus. It is the perspective view which illustrated the double-sided lap device. (A)-(d) is the figure which illustrated the grinding process in a double-sided grinding apparatus.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

(Embodiment 1)
<Double-sided grinding machine: Offset arrangement>
A double-sided grinding apparatus 1 according to Embodiment 1 will be described. In the double-side grinding apparatus 1 of the present embodiment, the rotation axes of the upper and lower grindstones are offset to maintain the shape of the grindstone surface. First, the configuration of the double-side grinding apparatus 1 will be described. FIG. 1 is a perspective view illustrating the main part of a double-side grinding apparatus 1 according to the first embodiment. FIG. 2 is a perspective view illustrating a state during processing of the double-side grinding apparatus 1 according to the first embodiment.

  As shown in FIGS. 1 and 2, the double-side grinding apparatus 1 includes a lower grindstone 10, a lower main body portion 17, a lower dress 18, a lower measuring device 19, an upper grindstone 20, an upper main body portion 27, an upper dress 28, and an upper measuring device. 29, a sun gear 30 and a counter gear 40 are provided. The double-sided grinding device 1 is a device that grinds both sides of the grinding object 50 held by the carrier gear 55.

  The lower grindstone 10 is a disk-shaped member and has a first central axis C1. The first central axis C1 is the vertical direction. The lower grindstone 10 is disposed on the lower main body portion 17. The lower main body portion 17 has, for example, a cylindrical shape whose central axis is the vertical direction, but the shape of the lower main body portion 17 is not limited to a cylindrical shape, and may be a rectangular parallelepiped shape. The lower grindstone 10 rotates about the first central axis C1 as a rotation axis. The lower grindstone 10 is provided with a first grindstone surface 11 having an outer periphery with a first radius R1 from the first central axis C1. The first grindstone surface 11 is provided so as to face upward. The lower grindstone 10 grinds the grinding object 50 disposed on the first grindstone surface 11.

  The upper grindstone 20 is a disk-shaped member and has a second central axis C2. The second central axis C2 is parallel to the first central axis C1 and is in the vertical direction. The upper grindstone 20 is disposed below the upper main body portion 27. The upper main body 27 has, for example, a cylindrical shape whose central axis is the vertical direction, but the upper main body 27 is not limited to a cylindrical shape and may be a rectangular parallelepiped. The second central axis C2 is disposed at a distance from the first central axis. The upper grindstone 20 rotates about the second central axis C2 as a rotation axis. The upper grindstone 20 is provided with a second grindstone surface 21 having an outer periphery with a second radius R2 from the second central axis C2. The second grindstone surface 21 is provided so as to face downward.

  Thus, the lower grindstone 10 and the upper grindstone 20 have an offset arrangement in which the rotation axes are arranged at intervals. The second grindstone surface 21 in the upper grindstone 20 and the first grindstone surface 11 in the lower grindstone 10 are partially opposed. A region where the first grindstone surface 11 and the second grindstone surface 21 face each other is called a grinding region. The upper grindstone 20 grinds the grinding object 50 arranged in the grinding region.

  An inner hole 26 is provided in the second grindstone surface 21. The inner hole 26 opens downward. The inner hole 26 is coaxial with the second central axis C2. A counter gear 40 is disposed in the inner hole 26.

  The counter gear 40 is a gear-shaped member, and a plurality of teeth are formed on the outer periphery. The counter gear 40 has a central axis. The counter gear 40 is disposed in the inner hole 26 provided in the upper grindstone 20 so that the central axis of the counter gear 40 is coaxial with the second central axis C2. However, the counter gear 40 has a portion protruding downward from the second grindstone surface 21. The counter gear 40 rotates about the second central axis C2 as a rotation axis. When viewed from above, the counter gear 40 is disposed outside the lower grindstone 10.

  The sun gear 30 is a gear-shaped member, and a plurality of teeth are formed on the outer periphery. The sun gear 30 has a central axis. The sun gear 30 is provided on the first grindstone surface 11 of the lower grindstone 10 so that the central axis of the sun gear 30 is coaxial with the first central axis C1. The sun gear 30 rotates about the first central axis C1 as a rotation axis. When viewed from above, the sun gear 30 is disposed outside the upper grindstone 20.

  The ground object 50 is a member having both flat surfaces. The ground object 50 is, for example, a wafer. The ground 50 is not limited to a wafer as long as it has both flat surfaces to be ground. Both surfaces of the grinding object 50 are referred to as a first surface 51 and a second surface 52. The second surface 52 is a surface opposite to the first surface 51.

  The ground object 50 is disposed in a grinding region where the first grindstone surface 11 and the second grindstone surface 21 face each other. The first surface 51 of the ground object 50 is in contact with the first grindstone surface 11 of the lower grindstone 10, and the second surface 52 of the ground object 50 is in contact with the second grindstone surface 21 of the upper grindstone 20. Thereby, the first surface 51 of the ground object 50 is ground by the first grindstone surface 11, and the second surface 52 of the ground object 50 is ground by the second grindstone surface 21.

  The carrier gear 55 is a gear-shaped member, and a plurality of teeth are formed on the outer peripheral surface. Further, the carrier gear 55 is provided with a holding hole for holding the grinding object 50 therein. Since the carrier gear 55 holds the ground object 50, it is also simply referred to as a carrier. In that case, the plurality of teeth on the outer periphery is called a carrier gear.

  The center axis of the carrier gear 55 may be shifted from the center axis of the holding hole. The carrier gear 55 surrounds the outer peripheral surface of the abrasive 50 and holds the abrasive 50. The ground object 50 is fitted and held in a holding hole, for example. The thickness of the carrier gear 55 is thinner than the thickness of the grinding object 50. For example, the thickness of the carrier gear 55 is 70 [μm]. Therefore, the first surface 51 and the second surface 52 of the grinding object 50 held by the carrier gear 55 protrude from the holding hole.

  The carrier gear 55 that holds the ground object 50 is disposed between the upper grindstone 20 and the lower grindstone 10. In this case, when viewed from above, the grinding object 50 held by the carrier gear 55 is disposed in the grinding region. On the other hand, the teeth of the carrier gear 55 have a portion protruding outward from the first grindstone surface 11 and a portion protruding outward from the second grindstone surface 21 when viewed from above.

  Portions of the teeth of the carrier gear 55 that protrude outward from the first grindstone surface 11 mesh with the teeth of the counter gear 40. Thereby, the counter gear 40 rotates the carrier gear 55 that holds the grinding object 50 in a plane parallel to the first grindstone surface 11. Portions of the teeth of the carrier gear 55 that protrude outward from the second grindstone surface 21 mesh with the teeth of the sun gear 30. Accordingly, the sun gear 30 rotates the carrier gear 55 that holds the grinding object 50 in a plane parallel to the first grindstone surface 11.

  The lower dress 18 is disposed on the first grindstone surface 11 of the lower grindstone 10. The lower dress 18 is in contact with a portion other than the grinding region on the first grindstone surface 11. The lower dress 18 sharpens the first grindstone surface 11. The lower measuring device 19 is disposed on the first grindstone surface 11. The lower measuring device 19 measures the shape and sharpening state of the first grindstone surface 11.

  The upper dress 28 is disposed so as to contact the second grindstone surface 21 of the upper grindstone 20. The upper dress 28 is in contact with a portion other than the grinding region on the second grindstone surface 21. The upper dress 28 sharpens the second grindstone surface 21. The upper measuring device 29 is disposed on the second grindstone surface 21. The upper measuring instrument 29 measures the shape and sharpening state of the second grindstone surface 21.

  In conjunction with the rotation of the sun gear 30 with the first central axis C1 as the rotational axis, the counter gear 40 also rotates with the second central axis C2 as the rotational axis. The carrier gear 55 that meshes with the sun gear 30 and the counter gear 40 rotates in a plane parallel to the first grindstone surface 11 between the first grindstone surface 11 and the second grindstone surface 21. On the other hand, the lower grindstone 10 rotates with the first central axis C1 as a rotation axis, and the upper grindstone 20 rotates with the second central axis C2 as a rotation axis. Thereby, the first surface 51 of the ground object 50 is ground by the first grindstone surface 11, and the second surface 52 of the ground object 50 is ground by the second grindstone surface 21.

  FIG. 3 is a cross-sectional view illustrating the lower grindstone 10 and the upper grindstone 20 of the double-side grinding apparatus 1 according to the first embodiment. As shown in FIG. 3, the first central axis C <b> 1 of the lower grindstone 10 and the second central axis of the upper grindstone 20 are parallel to each other and are arranged at a predetermined interval. A distance between the first central axis C1 and the second central axis C2 is referred to as a pitch Of. Further, a direction perpendicular to the first central axis C1 and the second central axis C2 and connecting the first central axis C1 and the second central axis C2 is defined as a pitch direction. The length of the grinding region in the pitch direction is defined as a grinding region length UL. The outer diameter Φ of the grinding object 50 is W.

  If it does so, in the double-sided grinding apparatus 1 of this embodiment, the lower grindstone 10 and the upper grindstone 20 are arrange | positioned so that the following (1) Formula and (2) Formula may be satisfy | filled.

W <Min (Of, R1, R2) (1)
| R2-R1 | + W <Of <R1 + R2-W (2)

  In this embodiment, in order to arrange the upper dress 28, the first grindstone surface 11 partially covers the second grindstone surface 21 from below. The first grindstone surface 11 does not cover the center of the second grindstone surface 21. Therefore, the grinding region length UL <the second radius R2. Moreover, in order to arrange the lower dress 18, the second grindstone surface 21 partially covers the first grindstone surface 11 from above. The second grindstone surface 21 does not cover the center of the first grindstone surface 11. Therefore, the grinding region length UL <the first radius R1. Further, the grinding region length UL <pitch Of. Since the grinding object 50 is disposed in the grinding region, the outer diameter W of the grinding object 50 is smaller than the grinding region length UL. Therefore, the outer diameter W <the first radius R1, the outer diameter W <the second radius R2, and the outer diameter W <the pitch Of. Thereby, (1) Formula is satisfy | filled.

  If the first central axis C1 and the second central axis C2 are brought closer to each other in the pitch direction, the outer periphery having the larger radius of the first grindstone surface 11 or the second grindstone surface 21 is the first grindstone surface 11 or the second grindstone surface. Crosses the center of the grindstone surface 21. For example, when the first radius R <b> 1 <the second radius R <b> 2, the outer periphery of the second grindstone surface 21 intersects the center of the first grindstone surface 11. In this state, the first radius R1 = grinding region length UL and the second radius R2 = pitch Of.

  In order to dispose the lower dress 18 and the upper dress 28, | second radius R2−first radius R1 | + grinding region length UL <pitch Of, so outer diameter W <grinding region length UL | R2-R1 | + W <Of.

  Further, in order to form the grinding region, the first grindstone surface 11 and the second grindstone surface 21 must be opposed to each other, so that pitch Of <first radius R1 + second radius R2 is necessary. The grinding region length UL in which the first grindstone surface 11 and the second grindstone surface 21 face each other is the grinding region length UL = first radius R1 + second radius R2-Of. In order to arrange the grinding object 50 having the outer diameter W within the grinding region length UL, the grinding region length UL must be larger than the outer diameter W, so that the outer diameter W <the grinding region length UL. . Therefore, the outer diameter W <the first radius R1 + the second radius R2-Of, and Of <R1 + R2-W. Thereby, the formula (2) is satisfied.

  In this embodiment, the lower whetstone 10 and the upper whetstone 20 are arrange | positioned so that (1) Formula and (2) Formula may be satisfy | filled. Therefore, the lower dress 18 and the upper dress 28 can be disposed on the surfaces 18a and 28a that require dressing on the first grindstone surface 11 and the second grindstone surface 21, respectively. Therefore, the first grindstone surface 11 and the second grindstone surface 21 can be sharpened. Thereby, even if the shape of the 1st grindstone surface 11 and the 2nd grindstone surface 21 which is a process surface collapses by grinding process, a shape can be always prepared and can be conspicuous. Moreover, the shape and sharpening state of the 1st grindstone surface 11 and the 2nd grindstone surface 21 can always be measured. Thus, the double-sided grinding apparatus 1 of this embodiment can make the 1st grindstone surface 11 and the 2nd grindstone surface 21 flat and parallel, and improves the flatness and parallelism of both surfaces of the grinding object 50. be able to.

  4A to 4D are cross-sectional views illustrating the positional relationship between the lower grindstone 10 and the upper grindstone 20. As shown in FIG. 4A, when the pitch Of> the first radius R1 + the second radius R2, the first grindstone surface 11 and the second grindstone surface 21 do not face each other. Therefore, since the grinding region is not formed, the grinding object 50 cannot be ground.

  As shown in FIG. 4B, in the case of | second radius R2−first radius R1 | + outer diameter W> pitch Of, the first grindstone surface 11 includes the center of the second grindstone surface 21. The second grindstone surface 21 is covered. The second grindstone surface 21 covers the first grindstone surface 11 so as to include the center of the first grindstone surface 11. Therefore, there is a surface 18b on which the lower dress 18 cannot be arranged, and the first grindstone surface 11 and the second grindstone surface 21 cannot be sharpened. Moreover, the shape and sharpening state of the 1st grindstone surface 11 and the 2nd grindstone surface 21 cannot be measured. The double-side grinding apparatuses of Patent Document 2 and Patent Document 3 correspond to this case.

  As shown in FIG. 4C, when the outer diameter W> the first radius R <b> 1 or the pitch Of, the grinding object 50 covers the first grindstone surface 11 so as to include the center of the first grindstone surface 11. Therefore, there is a surface 18b on which the lower dress 18 cannot be arranged, and the first grindstone surface 11 cannot be sharpened. Further, the shape and sharpening state of the first grindstone surface 11 cannot be measured.

  As shown in FIG. 4D, when the outer diameter W> the second radius R <b> 2, the grinding object 50 covers the second grindstone surface 21 so as to include the center of the second grindstone surface 21. Therefore, there is a surface 20b on which the upper dress 28 cannot be arranged, and the second grindstone surface 21 cannot be sharpened. The double-side grinding apparatus of Patent Document 1 corresponds to this case. As described above, in the case of FIGS. 4A to 4D, there is a region in which the grinding wheel surface is not always sharpened while processing, so the first grinding wheel surface 11 and the second grinding wheel surface 21 are parallel to each other. Can not do it. Therefore, the grinding object 50 cannot be ground flat and parallel.

  FIG. 5 is a perspective view illustrating a double-side grinding apparatus 101 in which the lower grindstone 10 and the upper grindstone 20 have a coaxial C rotating structure. As shown in FIG. 5, the double-side grinding apparatus 101 in which the ring gear 160 having an inner diameter larger than that of the upper grindstone 20 is arranged on the same axis C has a thin grinding object 50 without interference even when the lower grindstone 10 and the upper grindstone 20 approach each other. Can be ground. However, the lower dress 18 and the upper dress 28 for sharpening the lower grindstone 10 and the upper grindstone 20 cannot be arranged. Further, the lower measuring device 19 and the upper measuring device 29 for measuring the dress state cannot be arranged. Therefore, it is not possible to always make sharpening to prepare the grindstone surface while processing, and it is difficult to grind the grinding object 50 flatly.

  6A to 6C are diagrams illustrating the displacement of the lower grindstone 10 and the upper grindstone 20 in the double-side grinding apparatus 101 in which the lower grindstone 10 and the upper grindstone 20 have a coaxial C rotating structure. ) Is 100 [N], (b) is 500 [N], and (c) is 1000 [N]. In each figure, the upper stage shows the amount of displacement in gray scale, and the lower stage shows the cross-sectional shapes of the first grindstone surface 11 and the second grindstone surface 21.

  As shown in FIGS. 6A to 6C, when the load increases, the amount of displacement in the lower grindstone 10 and the upper grindstone 20 increases. The first grindstone surface 11 of the lower grindstone 10 and the second grindstone surface 21 of the upper grindstone 20 change in a mouth-open shape. The maximum displacement difference between the first grindstone surface 11 and the second grindstone surface 21 in FIGS. 6A, 6B and 6C is 1.4 [μm], 7.0 [μm] and 14.0 [μm]. Thus, in the double-sided grinding apparatus 101 in which the lower grindstone 10 and the upper grindstone 20 have a coaxial C rotating structure, the first grindstone surface 11 and the second grindstone surface 21 have a mouth-opening shape, so both surfaces of the grinding object 50 are formed. Are difficult to parallel.

  7A to 7C are diagrams illustrating the displacement of the lower grindstone 10 and the upper grindstone 20 in the double-side grinding apparatus 1 according to the first embodiment. FIG. 7A is a diagram illustrating a load of 100 [N]. (B) has a load of 500 [N], and (c) has a load of 1000 [N]. In each figure, the upper stage shows the amount of displacement in gray scale, and the lower stage shows the cross-sectional shapes of the first grindstone surface 11 and the second grindstone surface 21.

  As shown in FIGS. 7A to 7C, when the load increases, the amount of displacement in the lower grindstone 10 and the upper grindstone 20 increases as in the case of FIG. However, the 1st grindstone surface 11 and the 2nd grindstone surface 21 can maintain parallelism. Moreover, the maximum value of the displacement difference between the first grindstone surface 11 and the second grindstone surface 21 in FIGS. 7A, 7B and 7C is 0.22 [μm] and 1.1 [μm, respectively. ] And 2.2 [μm], and the amount of displacement with respect to the load can be reduced as compared with FIG. If the first central axis C1 and the second central axis C2 have the same rigidity and are symmetrically offset with respect to the center of the grinding object 50, the first grindstone surface 11 and the second grindstone surface 21 may be brought closer to parallel. it can. Thus, the double-sided grinding apparatus 1 of this embodiment can improve the flatness and parallelism of the 1st grindstone surface 11 and the 2nd grindstone surface 21 compared with the double-sided grinding apparatus 101 of a coaxial structure.

<Carrier gear rotation drive mechanism>
Next, a carrier gear rotation drive mechanism that improves the surface roughness of both surfaces of the grinding object 50 will be described. First, the carrier gear rotation drive mechanism of the double-side grinding apparatus 1 according to the first embodiment will be described. FIG. 8 is a cross-sectional perspective view illustrating the rotation drive mechanism of the carrier gear 55 in the double-side grinding apparatus 1 according to the first embodiment. FIG. 9 is a cross-sectional view illustrating a rotation driving mechanism of the carrier gear 55 in the double-side grinding apparatus 1 according to the first embodiment. FIG. 10 is an explanatory view illustrating a rotation driving mechanism of the carrier gear 55 in the double-side grinding apparatus 1 according to the first embodiment.

  As shown in FIGS. 8 to 10, the double-side grinding apparatus 1 includes a sun gear shaft 32, a sun gear drive gear 33, a carrier drive shaft 42, a carrier drive gear 43, a carrier drive motor 44, and an idle gear 45 in addition to the members described above. , A lower spindle 12, a lower spindle drive pulley 13, a lower spindle drive motor 14, a lower spindle drive motor pulley 15, and a lower spindle drive belt 16. Further, the double-side grinding apparatus 1 includes a lower main shaft bearing 91, a sun gear shaft bearing 93, and a carrier shaft bearing 94.

  The sun gear shaft 32 is a rod-like member extending in the vertical direction, and is disposed at the center of the lower main body portion 17. The sun gear shaft 32 is coaxial with the first central axis C1. The upper end of the sun gear shaft 32 is connected to the sun gear 30. A sun gear drive gear 33 is connected to the lower end of the sun gear shaft 32. The sun gear shaft bearing 93 supports the rotating sun gear shaft 32.

  The sun gear drive gear 33 is a gear-shaped member. The central axis of the sun gear drive gear 33 is coaxial with the first central axis C1. The sun gear drive gear 33 is connected to the lower end of the sun gear shaft 32. Therefore, the sun gear drive gear 33 rotates with the sun gear 30 about the first central axis C1 as a rotation axis.

  The carrier drive shaft 42 is a rod-like member extending in the vertical direction, and is disposed on the side of the lower main body portion 17. The carrier drive shaft 42 is coaxial with the second central axis C2. The upper end of the carrier drive shaft 42 is connected to the counter gear 40. A carrier drive gear 43 is connected to the lower end of the carrier drive shaft 42. The carrier shaft bearing 94 supports the rotating carrier driving shaft 42.

  The carrier drive gear 43 is a gear-shaped member. The center axis of the carrier drive gear 43 is coaxial with the second center axis C2. The carrier drive gear 43 is connected to the lower end of the carrier drive shaft 42. Therefore, the carrier drive gear 43 rotates with the counter gear 40 about the second central axis C2 as a rotation axis.

  The carrier drive motor 44 is disposed on the side of the lower main body portion 17. The carrier drive motor 44 transmits to the carrier drive shaft 42 a drive force that rotates the second central axis C1 as a rotation axis.

  The idle gear 45 is a gear-shaped member. The central axis of the idle gear 45 is parallel to the first central axis C1 and the second central axis C2, and is in the vertical direction. The idle gear 45 is disposed between the sun gear drive gear 33 and the carrier drive gear 43. The teeth of the idle gear 45 are in mesh with the teeth of the sun gear drive gear 33 and the carrier drive gear 43. Therefore, the rotation of the carrier drive gear 43 is transmitted to the sun gear drive gear 33 via the idle gear 45. Therefore, the rotation transmitted to the carrier drive shaft 42 by the carrier drive motor 44 is transmitted to the sun gear drive gear 33 via the carrier drive gear 43 and the idle gear 45 to rotate the sun gear shaft 32.

  For example, by setting the number of teeth of the sun gear drive gear 33 and the number of teeth of the carrier drive gear 43 to be the same, the sun gear 30 and the counter gear 40 can be rotated in the same direction at the same rotational speed. Further, by setting the number of teeth of the sun gear 30 and the number of teeth of the counter gear 40 to be the same, the carrier gear 55 can be rotated in the grinding region on the lower grindstone 10.

  The lower main shaft 12 is a cylindrical member extending in the vertical direction, and is disposed at the center of the lower main body portion 17. The lower main shaft 12 is coaxial with the first central axis C1. The lower main shaft 12 is disposed so as to include the sun gear shaft 32. That is, the sun gear shaft 32 is disposed coaxially within the lower main shaft 12. The upper end of the lower spindle 12 is connected to the lower grindstone 10. A lower spindle driving pulley 13 is connected to the lower end of the lower spindle 12. The lower spindle bearing 91 supports the rotating lower spindle 12.

  The lower spindle driving pulley 13 is a disk-shaped member. The central axis of the lower spindle driving pulley 13 is coaxial with the first central axis C1.

  The lower spindle driving motor 14 is disposed on the side of the lower main body portion 17. A lower spindle drive motor pulley 15 is connected to the lower spindle drive motor 14. The lower spindle drive motor pulley 15 is a disk-shaped member. The central axis of the lower spindle driving motor pulley 15 is parallel to the first central axis C1 and the second central axis C2, and is in the vertical direction. The lower spindle driving motor 14 transmits a rotational driving force to the lower spindle driving motor pulley 15.

  The lower spindle driving belt 16 connects the lower spindle driving pulley 13 and the lower spindle driving motor pulley 15. Accordingly, the rotation of the lower spindle driving motor pulley 15 is transmitted to the lower spindle driving pulley 13 via the lower spindle driving belt 16. Therefore, the rotation transmitted to the lower spindle drive motor pulley 15 by the lower spindle drive motor 14 is transmitted to the lower spindle 12 via the lower spindle drive belt 16 and the lower spindle drive pulley 13 to rotate the lower grindstone 10. Although not shown, the upper grindstone 20 is also rotated by the same mechanism as the lower grindstone 10.

  Thus, the double-sided grinding apparatus 1 of this embodiment can grind the thin grinding | polishing thing 50, without interfering, even if the 1st grindstone surface 11 of the lower grindstone 10 and the 2nd grindstone surface of the upper grindstone 20 approach. it can.

  FIG. 11A is a view exemplifying a processing mark 53 on the grinding surface of the grinding object 50 when the grinding object 50 is not rotated, and FIG. 11B is a diagram illustrating the grinding object in the double-side grinding apparatus 1 according to the first embodiment. It is the figure which illustrated the processing mark 53 of 50 grinding surfaces.

  As shown in FIG. 11A, when the carrier 155 is not rotated, a one-way processed stitch 53 is generated on the ground surface of the workpiece 50. Therefore, the characteristics of the ground surface of the grinding object 50 depend on the location, and there is a possibility that deviation occurs. In addition, there is a possibility that deviation occurs in the abrasion of the grindstone surface.

  In contrast, as shown in FIG. 11B, in the present embodiment, the carrier gear 55 that holds the grinding object 50 is rotated. Therefore, multidirectional machining marks 53 are generated on the ground surface of the grinding object 50, and the machining marks 53 are averaged. Therefore, the characteristics of the ground surface of the grinding object 50 can be improved. Moreover, since the 1st grindstone surface 11 and the 2nd grindstone surface 21 are used uniformly, shape collapse can be suppressed.

Next, the effect of Embodiment 1 is demonstrated.
The double-side grinding apparatus 1 of the present embodiment has an offset arrangement in which the rotation axis of the lower grindstone 10 and the rotation axis of the upper grindstone 20 are arranged with an interval therebetween. Therefore, the area | region below the radius of the lower grindstone 10 and the upper grindstone 20 can be made into a grinding process area | region. Thereby, the lower dress 18 and the upper dress 28 can be arranged in a region other than the grinding region. Accordingly, since the first grindstone surface 11 and the second grindstone surface 21 can be sharpened even during grinding, it is possible to suppress the occurrence of variations in the degree of wear of the lower grindstone 10 and the upper grindstone 20. Therefore, the flatness and parallelism of both surfaces of the grinding object 50 can be improved.

  Moreover, since the measuring device which measures the shape and sharpening state of the 1st grindstone surface 11 and the 2nd grindstone surface 21 can be arrange | positioned, the shape of the 1st grindstone surface 11 and the 2nd grindstone surface 21 at the time of grinding processing, and Sharpness can be measured. Therefore, the flatness and parallelism of both surfaces of the grinding object 50 can be improved.

  Furthermore, while making the rigidity with respect to the rotating shaft of the lower grindstone 10 and the upper grindstone 20 equal, the lower grindstone 10 and the upper grindstone 20 are arranged symmetrically with respect to the processing center, so that the flatness and parallelism of both surfaces of the grinding object 50 are achieved. The property can be further improved.

  The sun gear 30 is disposed outside the upper grindstone 20 as viewed from above, and the counter gear 40 is disposed in an inner hole 26 provided in the upper grindstone 20. Therefore, the lower grindstone 10 and the upper grindstone 20 can process the grinding object 50 without interfering with the sun gear 30 and the counter gear 40.

  The sun gear shaft 32 that transmits the rotational driving force to the sun gear 30 and the carrier driving shaft 42 that transmits the rotational driving force to the counter gear 40 are connected via the sun gear driving gear 33, the idle gear 45 and the carrier driving gear 43. Yes. Therefore, the sun gear 30 and the counter gear 40 are synchronized, and the carrier gear 55 can be stably rotated. Moreover, since it is rotated synchronously, it is sufficient to provide only one carrier drive motor 44 that rotates the carrier drive shaft 42. In addition, the number of control axes can be reduced. Thus, cost and size can be reduced.

  The carrier gear 55 holding the ground 50 is rotated on the first grindstone surface 11. Therefore, the processed stitches 53 are averaged, and the characteristics of the ground surface of the grinding object 50 can be improved. Moreover, since a grindstone surface is used uniformly, shape collapse can be suppressed.

(Embodiment 2)
<Truing technique>
Next, Embodiment 2 will be described. The second embodiment is a tooling method in a double-side grinding apparatus of an upper and lower grinding wheel offset drive type. The truing method is a method of sharpening the grindstone surface of the grindstone. In order to ensure the flatness and parallelism of both surfaces of the ground object 50 when performing grinding processing such as double-sided polishing on the ground object 50 such as a wafer, truing that sharpens the broken shape of the grindstone surface is performed. is necessary. Truing is performed when the lower grindstone 10 and the upper grindstone 20 are replaced or when wear progresses. First, the truing technique according to Comparative Example 1 will be described. Thereafter, the truing technique of the present embodiment will be described in comparison with Comparative Example 1. Further, Comparative Examples 2 to 4 will be described.

  A truing technique according to Comparative Example 1 will be described. 12A to 12D are diagrams illustrating a truing technique for the lower grindstone 10 and the upper grindstone 20 in the double-side grinding apparatus 201 according to Comparative Example 1, and FIGS. 12A and 12D are cross-sectional perspective views. The figure is shown, (b) and (c) have shown the schematic diagram.

  As shown in FIG. 12A, in the general truing method according to Comparative Example 1, the truing grindstone 165 for correction is sandwiched and rotated between the lower grindstone 10 and the upper grindstone 20. As shown in FIG. 12B, the truing grindstone 165 is sandwiched from both the lower grindstone 10 and the upper grindstone 20. Then, while both the lower grindstone 10 and the upper grindstone 20 are rotated, they are sandwiched to perform surface matching.

  However, in practice, as shown in FIG. 12C, the reduction speed of the truing grindstone 165 sandwiched between the lower grindstone 10 and the upper grindstone 20 does not necessarily match. In particular, when the reduction speed of the truing grindstone 165 is greater than the truing speed, no pinching force is generated, and only the first grindstone surface 11 of the lower grindstone 10 is roughened only by its own weight. Further, even when the reduction speed of the truing grindstone 165 is smaller than the truing speed, the same surface-matching force is not obtained between the lower grindstone 10 and the upper grindstone 20. Therefore, as shown in FIG. 12D, after the truing, the first grindstone surface 11 and the second grindstone surface 21 become uneven.

  Next, the truing technique according to the second embodiment will be described. FIGS. 13A to 13C are diagrams illustrating a truing technique of the lower grindstone 10 and the upper grindstone 20 in the double-side grinding apparatus 2 according to the second embodiment. FIGS. 13A and 13C are cross-sectional perspective views. A figure is shown and (b) shows a mimetic diagram. Since the structure of the double-sided grinding apparatus 2 of this embodiment is the same as the structure of the double-sided grinding apparatus 1 of Embodiment 1, description is abbreviate | omitted.

  As shown to Fig.13 (a), in the double-sided grinding apparatus 2 which concerns on this embodiment, the truing grindstone 165 is not used. While rotating the lower grindstone 10 and the upper grindstone 20 at slightly different rotational speeds, both are pressed directly. If the rotation speeds of the lower grindstone 10 and the upper grindstone 20 are equal, surface matching occurs at the same phase, and it becomes difficult to make uniform over 360 [°].

  As shown in FIG. 13B, in the present embodiment, the surface matching forces applied to the first grindstone surface 11 of the lower grindstone 10 and the second grindstone surface 21 of the upper grindstone 20 are equal. Therefore, since it becomes ideal surface alignment, as shown in FIG.13 (c), the flatness and parallelism in the 1st grindstone surface 11 and the 2nd grindstone surface 21 can be improved.

  Next, a truing technique according to Comparative Example 2 will be described. 14A and 14B are cross-sectional perspective views illustrating the truing technique of the lower grindstone 10 and the upper grindstone 20 in the double-side grinding apparatus 202 according to Comparative Example 2. FIG.

  As shown in FIG. 14A, in the double-side grinding apparatus 202 in which the lower grindstone 10 and the upper grindstone 20 have a coaxial C rotating structure, when a truing grindstone 165 that does not rotate is used, the same truing grindstone 165 is used. The grindstone surface is in contact with the first grindstone surface 11 and the second grindstone surface 21. Accordingly, as shown in FIG. 14B, the curved shapes of the first grindstone surface 11 and the second grindstone surface 21 cannot be corrected even if truing is performed.

  Next, a truing technique according to Comparative Example 3 will be described. 15A and 15B are cross-sectional perspective views illustrating the truing technique of the lower grindstone 10 and the upper grindstone 20 in the double-side grinding apparatus 203 according to Comparative Example 3.

  As shown in FIG. 15A, in the double-side grinding apparatus 203 in which the lower grindstone 10 and the upper grindstone 20 have a coaxial C rotating structure, when the truing grindstone 165 rotated and rotated is used, the truing grindstone 165 is The lower grindstone 10 and the upper grindstone 20 move to the outside away from the coaxial C. If it does so, the 1st whetstone surface 11 and the 2nd whetstone surface 21 will be displaced in the shape of a mouth spreading on the outside. In this case, as shown in FIG. 15 (b), when the truing grindstone 165 is released, the lower grindstone 10 and the upper grindstone 20 are spring-backed and displaced in the form of an opening that spreads inward. Thus, in the comparative example 3, although the 1st grindstone surface 11 and the 2nd grindstone surface 21 are flat, they are trued so that it may have a taper.

  Next, a truing technique according to Comparative Example 4 will be described. FIGS. 16A and 16B are cross-sectional perspective views illustrating the truing technique of the lower grindstone 10 and the upper grindstone 20 in the double-side grinding apparatus 204 according to Comparative Example 4. FIG.

  As shown in FIG. 16A, in the double-side grinding apparatus 204 in which the lower grindstone 10 and the upper grindstone 20 have a coaxial C rotating structure, when the truing grindstone 165 is not used, the first grindstone surface 11 and the second grindstone The grindstone surface 21 rotates on the same axis C. And the 1st grindstone surface 11 rotates so that the same processed stitch as the 2nd grindstone surface 21 may contact in a radial direction. Therefore, as shown in FIG. 16B, the curved shapes of the first grindstone surface 11 and the second grindstone surface 21 cannot be corrected even if truing is performed.

Next, the effect of this embodiment will be described.
The truing method of the double-side grinding apparatus 2 of the present embodiment does not use the truing grindstone 165 but equalizes the surface-matching forces applied to the first grindstone surface 11 of the lower grindstone 10 and the second grindstone surface 21 of the upper grindstone 20. Therefore, the flatness and parallelism of the first grindstone surface 11 and the second grindstone surface 21 can be improved.

  In addition, since the rotation axes of the lower grindstone 10 and the upper grindstone 20 are offset, the processing wheels of the lower grindstone 10 and the upper grindstone 20 can be multidirectional, and flatness and parallelism can be improved. .

  Since the rotation speeds of the lower grindstone 10 and the upper grindstone 20 are different, the truing can be performed uniformly over 360 [°]. Other configurations and effects are included in the description of the first embodiment.

  The embodiment according to the present invention has been described above. However, the present invention is not limited to the above-described configuration, and modifications can be made without departing from the technical idea of the present invention.

1, 101, 201, 202, 203, 204 Double-side grinding apparatus 10 Lower grinding wheel 11 First grinding wheel surface 12 Lower main spindle 13 Lower main spindle driving pulley 14 Lower main spindle driving motor 15 Lower main spindle driving motor pulley 16 Lower main spindle driving belt 17 Lower main body portion 18 Lower dress 18a, 18b Surface 19 Lower measuring device 20 Upper grindstone 21 Second grindstone surface 26 Inner hole 27 Upper body 28 Upper dress 28a, 28b Surface 29 Upper measuring device 30 Sun gear 32 Sun gear shaft 33 Sun gear drive gear 40 Counter gear 42 Carrier drive shaft 43 Carrier drive gear 44 Carrier drive motor 45 Idle gear 50 Ground 51 First surface 52 Second surface 53 Machining 55 Carrier gear 91 Lower main shaft bearing 93 Sun gear shaft bearing 94 Carrier shaft bearing 155 Carrier 160 Ring gear 165 Truing Grinding wheel 171 Single-side grinding Table 172 Turntable 173 Wafer 174 Grinding wheel tip 175 Grinding wheel 191 Double-sided lapping device 192 Upper surface plate 193 Lower surface plate 194 Wafer 195 Carrier 196 Sun gear 197 Internal gear 201 Double-side grinding device 210 Lower wheel 220 Upper wheel 230 Carrier 240 Wafer C1 First Central axis C2 Second central axis R1 First radius R2 Second radius UL Grinding region length W Outer diameter

Claims (2)

A lower whetstone that rotates with a first central axis as a rotation axis, and is provided so that a first whetstone surface having an outer periphery of a first radius from the first central axis faces upward;
An upper grindstone that rotates with a second central axis parallel to the first central axis as a rotation axis, and a second grindstone surface having an outer periphery of a second radius from the second central axis faces downward;
With
A grinding object is disposed in a grinding region that is a region where the first grindstone surface and the second grindstone surface are opposed to each other,
When a direction perpendicular to the first central axis and the second central axis and connecting the first central axis and the second central axis is a pitch direction,
The pitch direction length of the grinding region is not more than the first radius and not more than the second radius.
Double-side grinding machine. A sun gear and a counter gear for rotating the carrier gear holding the grinding object in a plane parallel to the first grindstone surface;
The sun gear is disposed outside the upper grindstone as viewed from above,
The counter gear is disposed in an inner hole coaxial with the second central axis provided in the upper grindstone.
The double-sided grinding apparatus according to claim 1.