JP6171053B2 - Polishing equipment - Google Patents

Description

  The present invention relates to a polishing apparatus for polishing a substrate such as a wafer, and more particularly to a polishing apparatus for pressing a polishing tape against a peripheral portion of a substrate to polish the peripheral portion.

  In order to polish a peripheral portion of a wafer, a polishing apparatus provided with a polishing tool such as a polishing tape or fixed abrasive is used. This type of polishing apparatus polishes the peripheral portion of the wafer by bringing the polishing tool into contact with the peripheral portion of the wafer while rotating the wafer. In this specification, the peripheral portion of the wafer is defined as a region including a bevel portion located on the outermost periphery of the wafer and a top edge portion and a bottom edge portion located on the radially inner side of the bevel portion.

  FIGS. 37A and 37B are enlarged cross-sectional views showing the peripheral edge of the wafer. More specifically, FIG. 37A is a cross-sectional view of a so-called straight type wafer, and FIG. 37B is a cross-sectional view of a so-called round type wafer. In the wafer W of FIG. 37 (a), the bevel portion is formed of an upper inclined portion (upper bevel portion) P, a lower inclined portion (lower bevel portion) Q, and a side portion (apex) R. This is the outermost peripheral surface (indicated by reference sign B). In the wafer W of FIG. 37B, the bevel portion is a portion (indicated by reference numeral B) having a curved cross section that constitutes the outermost peripheral surface of the wafer W. The top edge portion is a flat portion E1 that is located on the radially inner side of the bevel portion B. The bottom edge portion is a flat portion E2 located on the opposite side of the top edge portion and located radially inward of the bevel portion B. Hereinafter, the top edge portion E1 and the bottom edge portion E2 are collectively referred to as an edge portion. The edge portion may include a region where a device is formed.

  In a manufacturing process of an SOI (Silicon on Insulator) substrate or the like, it is required to form a vertical plane and a horizontal plane at the edge portion of the wafer W as shown in FIG. Such a cross-sectional shape of the edge portion is achieved by a polishing method as shown in FIG. That is, the edge portion of the wafer W is polished by pressing the edge portion of the polishing tape 301 against the edge portion with the pressing pad 300 while rotating the wafer W. The lower surface of the polishing tape 301 constitutes a polishing surface holding abrasive grains, and this polishing surface is arranged in parallel with the wafer W. Then, by pressing the polishing surface of the polishing tape 301 against the edge portion of the wafer W with the pressing pad 300 in a state where the edge portion of the polishing tape 301 is positioned at the edge portion of the wafer W, as shown in FIG. , A perpendicular cross-sectional shape, that is, a vertical plane and a horizontal plane can be formed at the edge portion of the wafer W.

  However, since the contact area between the polishing tape and the horizontal plane differs depending on the position of the wafer edge portion in the horizontal plane, a part of the horizontal plane may be inclined as a result. This problem will be described with reference to the drawings. 40 is a top view showing the pressing pad 300 and the polishing tape 301 shown in FIG. The wafer W is circular, while the pressing pad 300 is rectangular. Therefore, the contact length (that is, the polishing area) between the polishing tape 301 and the wafer W is different between the radially inner region and the radially outer region of the wafer edge portion, as indicated by the dotted line in FIG. As a result, as shown in FIG. 41, the area inside the horizontal plane is inclined.

JP 2011-161625 A

  The present invention has been made to solve the above-described conventional problems, and an object thereof is to provide a polishing apparatus capable of forming a flat horizontal surface on an edge portion of a substrate such as a wafer.

In order to achieve the above-described object, according to one aspect of the present invention, in a polishing apparatus for polishing an edge portion of a substrate, a wafer holding portion that holds and rotates the substrate, and a pressing pad that presses the polishing tape against the edge portion of the substrate A tangential direction moving mechanism that is connected to the pressing pad and moves the pressing pad in a tangential direction of the substrate, and a polishing control unit that controls the operation of the polishing apparatus, wherein the polishing control unit Before the pad presses the polishing tape against the edge of the substrate, the tangential movement mechanism causes the pressing pad to move from the origin position on the center line extending radially from the center of the substrate to the tangential direction of the substrate. At a position shifted by a predetermined distance and above the edge of the substrate, and at the shifted position, the polishing table is moved by the pressing pad. The against the edge portion of the substrate, characterized by polishing the edge portion of the substrate.

In a preferred aspect of the present invention, the tangential direction is perpendicular to the center line .
In a preferred aspect of the present invention, the predetermined distance is less than half of the length of the pressing pad along the tangential direction.

In a preferred aspect of the present invention, the polishing tape extends in the tangential direction when viewed from above the substrate.
One aspect of the present invention is a polishing apparatus for polishing an edge portion of a substrate, a wafer holding portion that holds and rotates the substrate, a pressure pad that presses a polishing tape against the edge portion of the substrate, and the pressure pad, A tangential direction moving mechanism for moving the pressing pad in a tangential direction of the substrate, and the polishing tape extends in the tangential direction when viewed from above the substrate, and the edge of the pressing pad is The polishing tape is pressed against the edge portion of the substrate by the edge portion of the pressing pad in a state of being aligned with the edge portion of the polishing tape.
According to a preferred aspect of the present invention, in a state where a part of the polishing tape protrudes from an edge of the pressing pad, an area protruding from the edge of the pressing pad of the polishing tape by the pressing pad, and the pressing pad Both regions that do not protrude from the edge of the substrate are pressed against the edge of the substrate.
In a preferred aspect of the present invention, the polishing tape extends along the center line when viewed from above the substrate.

  According to the present invention, by shifting the position of the pressing pad in the tangential direction of the substrate, without changing the contact area between the inner region of the substrate edge portion and the polishing tape, the outer region of the substrate edge portion and the polishing tape The contact area can be reduced. Therefore, a flat horizontal surface can be formed on the substrate edge portion.

It is a mimetic diagram for explaining a polish device for carrying out one embodiment of a polish method concerning the present invention. FIG. 2 is a plan view of the polishing apparatus shown in FIG. 1. It is a figure for demonstrating one Embodiment of the grinding | polishing method which concerns on this invention. It is a figure which shows the state which shifted the press pad only the predetermined distance to the tangent direction from the origin position. It is a schematic diagram for demonstrating the grinding | polishing apparatus for enforcing the grinding | polishing method which concerns on other embodiment of this invention. FIG. 6 is a plan view of the polishing apparatus shown in FIG. 5. It is a figure for demonstrating the grinding | polishing method by the grinding | polishing apparatus shown in FIG. 5 and FIG. It is a figure which shows the state which shifted the press pad only the predetermined distance to the tangent direction from the origin position. It is a top view which shows one Embodiment of a grinding | polishing apparatus. FIG. 10 is a sectional view taken along line FF in FIG. 9. It is the figure seen from the direction shown by the arrow G of FIG. It is a top view of a polishing head and a polishing tape supply and recovery mechanism. It is a front view of a polishing head and a polishing tape supply and recovery mechanism. It is the HH sectional view taken on the line shown in FIG. FIG. 14 is a side view of the polishing tape supply / recovery mechanism shown in FIG. 13. It is the longitudinal cross-sectional view which looked at the polishing head shown in FIG. 13 from the direction shown by arrow I. It is the figure which looked at the position sensor and the dog from the top. It is a figure which shows the grinding | polishing head and the grinding | polishing tape supply / recovery mechanism which were moved to the predetermined grinding | polishing position. It is the schematic diagram which looked at the press pad in the polishing position, the polishing tape, and the wafer from the horizontal direction. It is a figure which shows the state which has pressed the polishing tape against the wafer with the press pad. It is a schematic diagram which shows the state which a part of polishing tape protrudes from the press pad. FIG. 22A to FIG. 22C are diagrams for explaining the operation when the edge of the polishing tape is detected. FIG. 23A is a view of the polishing tape and the pressing pad in the polishing position as viewed from the radial direction of the wafer, and FIG. 23B is a state where the lower surface of the pressing pad is in contact with the upper surface of the polishing tape. FIG. 23C is a diagram illustrating a state in which the pressing pad presses the polishing tape against the wafer from above. FIG. 24A is a diagram showing a state in which the wafer is bent as a result of pressing the polishing tape against the wafer with the pressing pad, and FIG. 24B is polished in the state shown in FIG. It is sectional drawing of a wafer. It is a longitudinal cross-sectional view which shows the wafer holding part provided with the support stage. It is a perspective view of a support stage. It is a figure which shows the state which the holding stage and the wafer hold | maintained on the upper surface raised relatively with respect to the support stage. It is a figure which shows embodiment provided with the tape stopper. It is a figure which shows the state which the abrasive tape received and received the load of the horizontal direction. It is a figure which shows embodiment with which the tape stopper and the tape cover were provided. It is a figure which shows embodiment provided with the movement restriction | limiting mechanism which restrict | limits the outward movement of a press pad. It is a figure which shows the example which combined embodiment shown in FIG. 25 and embodiment shown in FIG. It is a top view which shows other embodiment of a grinding | polishing apparatus. It is a longitudinal cross-sectional view of the grinding | polishing apparatus shown in FIG. FIG. 35 is an enlarged view of the polishing head shown in FIG. 34. It is a figure which shows a mode that the grinding | polishing head is grinding | polishing the top edge part of a wafer. FIGS. 37A and 37B are enlarged cross-sectional views showing the peripheral edge of the wafer. It is a figure which shows the vertical surface and horizontal surface which were formed in the edge part of a wafer. It is a figure for demonstrating the grinding | polishing method for forming the vertical surface and horizontal surface which are shown in FIG. It is a top view which shows the press pad and polishing tape shown in FIG. It is sectional drawing which shows the edge part of the grind | polished wafer.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic view for explaining a polishing apparatus for carrying out an embodiment of a polishing method according to the present invention, and FIG. 2 is a plan view of the polishing apparatus shown in FIG. The polishing apparatus includes a wafer holding unit 3 that holds and rotates the wafer W as a substrate, a pressing pad 51 that presses the polishing tape 38 against the edge of the wafer W, and a pressing mechanism 53 that presses the pressing pad 51 toward the wafer W. And a tangential direction moving mechanism 30 that moves the pressing pad 51 and the pressing mechanism 53 in the tangential direction of the wafer W. As the pressing mechanism 53, an air cylinder or a combination of a servo motor and a ball screw can be used. As the tangential direction moving mechanism 30, a combination of a servo motor and a ball screw can be used.

  The polishing tape 38 is arranged so that its polishing surface is parallel to the surface of the wafer W and the polishing surface faces the edge portion of the wafer W. One surface (lower surface) of the polishing tape 38 constitutes a polishing surface to which abrasive grains are fixed. The polishing tape 38 is a long polishing tool and is disposed along the tangential direction of the wafer W. The pressing pad 51 is a pressing member for pressing the polishing tape 38 against the edge portion of the wafer W, and is disposed above the edge portion of the wafer W. A tape stopper 185 that restricts the horizontal movement of the polishing tape 38 is fixed to the bottom surface of the pressing pad 51. This tape stopper 185 may be omitted.

  FIG. 3 is a view for explaining an embodiment of the polishing method according to the present invention. The origin position of the pressing pad 51 is set in advance on a center line CL extending in the radial direction from the center Cw of the wafer W. This origin position is a reference position of the pressing pad 51 when the edge portion of the wafer W is polished. The midpoint Cp of the inner edge 51b of the pressing pad 51 at the origin position is on the center line CL. The inner edge 51 b of the pressing pad 51 is an edge of a pressing surface that presses the polishing tape 38 against the edge of the wafer W, and is an inner edge in the radial direction of the wafer W.

  The polishing of the wafer W is performed as follows. First, the wafer W is rotated by the wafer holder 3. Then, with the edge of the pressing pad 51 aligned with the edge of the polishing tape 38, the edge of the polishing tape 38 is pressed against the rotating edge of the wafer W by the pressing pad 51 to polish the edge of the wafer W. To do. The polishing tape 38 may be pressed against the edge portion of the rotating wafer W by the pressing pad 51 in a state where a part of the polishing tape 38 is protruded radially inward from the edge portion of the pressing pad 51. The edge of the polishing tape 38 is a right-angled corner, and the right-angled edge is pressed from above onto the edge of the wafer W by the edge of the pressing pad 51. The polishing surface of the polishing tape 38 that is in contact with the wafer W is parallel to the surface of the wafer W. The inner edge of the pressing pad 51 during polishing is pressed against the edge of the wafer W via the polishing tape 38. The wafer pressing surface (substrate pressing surface) of the pressing pad 51 is a horizontal plane parallel to the wafer surface. By pressing the polishing tape 38 against the edge portion of the wafer W with this horizontal pressing surface, the surface perpendicular to the edge portion of the wafer W is obtained. And form a horizontal plane.

  However, as described above, the contact area between the polishing tape 38 and the wafer W varies depending on the position in the wafer edge portion, and as a result, as shown in FIG. 41, the region inside the horizontal plane may be inclined. Therefore, as shown in FIG. 4, the pressing pad 51 is shifted from the origin position by a predetermined distance in the tangential direction orthogonal to the center line CL, and the polishing tape 38 is pressed against the wafer W by the pressing pad 51 at this shifted position. As can be seen from FIG. 4, when the position of the pressing pad 51 is shifted in the tangential direction of the wafer W, the contact area (contact length) between the inner region of the wafer edge portion and the polishing tape 38 is not changed, and the outer side of the wafer edge portion is changed. The contact area between the region and the polishing tape 38 can be reduced. Therefore, the polishing tape 38 can form a flat horizontal surface as shown in FIG. The predetermined distance by which the pressing pad 51 is displaced is preferably less than half of the length of the pressing pad 51 along the tangential direction. With such a distance, the formation of the innermost vertical surface is hardly affected by the position of the pressing pad 51. It is possible to change the profile of the horizontal plane by adjusting the distance by which the pressing pad 51 is shifted from the origin position in the tangential direction orthogonal to the center line CL. For example, it is possible to form a horizontal plane having a desired angle by adjusting the distance shifted from the origin position of the pressing pad 51.

  The present invention can also be applied to a polishing method in which the polishing tape 38 is arranged in the radial direction of the wafer W. FIG. 5 is a schematic view for explaining a polishing apparatus for performing a polishing method according to another embodiment of the present invention, and FIG. 6 is a plan view of the polishing apparatus shown in FIG. The polishing apparatus shown in FIGS. 5 and 6 is configured so that the polishing tape 38 extends along the center line CL when viewed from above the wafer W (that is, the polishing tape 38 extends in the radial direction of the wafer W). ) Different from the polishing apparatus shown in FIGS. 1 and 2 in that the polishing tape 38 is disposed. Other configurations are the same as those of the polishing apparatus shown in FIGS.

  The polishing of the wafer W is performed as follows. First, the wafer W is rotated by the wafer holder 3. Then, the polishing pad 38 is pressed against the edge portion of the rotating wafer W by the pressing pad 51 to polish the edge portion of the wafer W. The inner edge of the pressing pad 51 during polishing is pressed against the edge of the wafer W via the polishing tape 38.

  FIG. 7 is a view for explaining a polishing method by the polishing apparatus shown in FIGS. 5 and 6. Similar to the above-described embodiment, the origin position of the pressing pad 51 is set in advance on the center line CL extending in the radial direction from the center Cw of the wafer W. The midpoint Cp of the inner edge 51b of the pressing pad 51 at the origin position is at the center line CL.

  When polishing the wafer W, as shown in FIG. 8, the pressing pad 51 is shifted from the origin position by a predetermined distance in the tangential direction perpendicular to the center line CL, and the polishing pad 38 is pressed by the pressing pad 51 at this shifted position. Is pressed against the wafer W. Also in this embodiment, the contact area between the outer region of the wafer edge portion and the polishing tape 38 can be reduced without changing the contact area (contact length) between the inner region of the wafer edge portion and the polishing tape 38. Therefore, a flat horizontal surface can be formed at the edge portion of the wafer W.

  Next, details of a polishing apparatus capable of executing the above-described embodiment of the polishing method shown in FIGS. 3 and 4 will be described. 9 is a plan view showing the polishing apparatus, FIG. 10 is a cross-sectional view taken along line FF in FIG. 9, and FIG. 11 is a view seen from the direction indicated by arrow G in FIG. The polishing apparatus includes a wafer holding unit 3 that horizontally holds and rotates a wafer (substrate) W that is an object to be polished. FIG. 9 shows a state in which the wafer holding unit 3 holds the wafer W. The wafer holding unit 3 includes a holding stage 4 that holds the lower surface of the wafer W by vacuum suction, a hollow shaft 5 that is connected to the center of the holding stage 4, and a motor M 1 that rotates the hollow shaft 5. . The wafer W is placed on the holding stage 4 so that the center of the wafer W coincides with the axis of the hollow shaft 5.

  The holding stage 4 is disposed in a polishing chamber 22 formed by a partition wall 20 and a base plate 21. The partition wall 20 includes a transfer port 20 a for carrying the wafer W into and out of the polishing chamber 22. The conveyance port 20a is formed as a notch extending horizontally. The transport port 20 a can be closed by a shutter 23.

  The hollow shaft 5 is supported by a ball spline bearing (linear motion bearing) 6 so as to be movable up and down. A groove 4 a is formed on the upper surface of the holding stage 4, and this groove 4 a communicates with a communication path 7 extending through the hollow shaft 5. The communication path 7 is connected to a vacuum line 9 via a rotary joint 8 attached to the lower end of the hollow shaft 5. The communication path 7 is also connected to a nitrogen gas supply line 10 for detaching the processed wafer W from the holding stage 4. By switching between the vacuum line 9 and the nitrogen gas supply line 10, the wafer W is held on the upper surface of the holding stage 4 and separated.

  The hollow shaft 5 is rotated by the motor M1 via a pulley p1 connected to the hollow shaft 5, a pulley p2 attached to the rotation shaft of the motor M1, and a belt b1 hung on the pulleys p1 and p2. . The ball spline bearing 6 is a bearing that allows the hollow shaft 5 to freely move in the longitudinal direction thereof. The ball spline bearing 6 is fixed to a cylindrical casing 12. Therefore, the hollow shaft 5 can move linearly up and down with respect to the casing 12, and the hollow shaft 5 and the casing 12 rotate integrally. The hollow shaft 5 is connected to an air cylinder (elevating mechanism) 15, and the hollow shaft 5 and the holding stage 4 can be raised and lowered by the air cylinder 15.

  A radial bearing 18 is interposed between the casing 12 and a cylindrical casing 14 disposed concentrically on the outside thereof, and the casing 12 is rotatably supported by the bearing 18. With such a configuration, the wafer holding unit 3 can rotate the wafer W around its central axis and raise and lower the wafer W along its central axis.

  A polishing unit 25 for polishing the peripheral edge of the wafer W is disposed outside the wafer W held in the wafer holding unit 3 in the radial direction. The polishing unit 25 is disposed inside the polishing chamber 22. As shown in FIG. 11, the entire polishing unit 25 is fixed on the installation table 27. The installation table 27 is connected to the polishing unit moving mechanism 30 via the arm block 28.

  The polishing unit moving mechanism 30 includes a ball screw mechanism 31 that holds the arm block 28, a motor 32 that drives the ball screw mechanism 31, and a power transmission mechanism 33 that connects the ball screw mechanism 31 and the motor 32. Yes. The power transmission mechanism 33 includes a pulley and a belt. When the motor 32 is operated, the ball screw mechanism 31 moves the arm block 28 in the direction indicated by the arrow in FIG. 11, and the entire polishing unit 25 moves in the tangential direction of the wafer W. The polishing unit moving mechanism 30 also functions as an oscillation mechanism that swings the polishing unit 25 at a predetermined amplitude and a predetermined speed.

  The polishing unit 25 includes a polishing head 50 that polishes the peripheral portion of the wafer W using the polishing tape 38, and a polishing tape supply and recovery mechanism 70 that supplies the polishing tape 38 to the polishing head 50 and collects it from the polishing head 50. ing. The polishing head 50 is a top edge polishing head that presses the polishing surface of the polishing tape 38 against the peripheral edge of the wafer W from above to polish the top edge portion of the wafer W.

  12 is a plan view of the polishing head 50 and the polishing tape supply / recovery mechanism 70, FIG. 13 is a front view of the polishing head 50 and the polishing tape supply / recovery mechanism 70, and FIG. 14 is a cross-sectional view taken along line HH shown in FIG. 15 is a side view of the polishing tape supply / recovery mechanism 70 shown in FIG. 13, and FIG. 16 is a longitudinal sectional view of the polishing head 50 shown in FIG.

  Two linear motion guides 40A and 40B extending in parallel with the radial direction of the wafer W are arranged on the installation table 27. The polishing head 50 and the linear motion guide 40A are connected via a connection block 41A. Further, the polishing head 50 is connected to a motor 42A and a ball screw 43A that move the polishing head 50 along the linear motion guide 40A (that is, in the radial direction of the wafer W). More specifically, the ball screw 43A is fixed to the connection block 41A, and the motor 42A is fixed to the installation base 27 via the support member 44A. The motor 42A is configured to rotate the screw shaft of the ball screw 43A, whereby the connecting block 41A and the polishing head 50 connected thereto are moved along the linear guide 40A. The motor 42A, the ball screw 43A, and the linear guide 40A constitute a first moving mechanism 45 that moves the polishing head 50 in the radial direction of the wafer W held by the wafer holding unit 3.

  Similarly, the polishing tape supply / recovery mechanism 70 and the linear motion guide 40B are coupled via a coupling block 41B. Further, the polishing tape supply / recovery mechanism 70 is connected to a motor 42B and a ball screw 43B that move the polishing tape supply / recovery mechanism 70 along the linear motion guide 40B (that is, in the radial direction of the wafer W). More specifically, the ball screw 43B is fixed to the connection block 41B, and the motor 42B is fixed to the installation base 27 via the support member 44B. The motor 42B is configured to rotate the screw shaft of the ball screw 43B, whereby the connecting block 41B and the polishing tape supply / recovery mechanism 70 connected thereto are moved along the linear motion guide 40B. The motor 42B, the ball screw 43B, and the linear guide 40B constitute a tape moving mechanism (second moving mechanism) 46 that moves the polishing tape 38 in the radial direction of the wafer W held by the wafer holding unit 3.

  As shown in FIG. 16, the polishing head 50 presses down the pressing pad 51 that presses the polishing tape 38 against the wafer W, the pad holder 52 that holds the pressing pad 51, and the pad holder 52 (and the pressing pad 51). And an air cylinder 53 as a pressing mechanism. The air cylinder 53 is held by a holding member 55. Further, the holding member 55 is connected to an air cylinder 56 as a lift mechanism via a linear motion guide 54 extending in the vertical direction. When a gas such as air is supplied to the air cylinder 56 from a gas supply source (not shown), the air cylinder 56 pushes up the holding member 55. Thereby, the holding member 55, the air cylinder 53, the pad holder 52, and the pressing pad 51 are lifted along the linear motion guide 54.

  In the present embodiment, the vertical movement mechanism 59 that moves the pressing pad 51 in a direction perpendicular to the wafer surface is constituted by an air cylinder 53 and an air cylinder 56. The first moving mechanism 45 including the motor 42A, the ball screw 43A, and the linear motion guide 40A also functions as a radial movement mechanism that moves the pressing pad 51 and the vertical movement mechanism in the radial direction of the wafer W. Further, the polishing unit moving mechanism 30 functions as a tangential direction moving mechanism that moves the pressing pad 51 (and the air cylinder 53 as the pressing mechanism) in the tangential direction of the wafer W.

  The air cylinder 56 is fixed to an installation member 57 fixed to the connection block 41A. The installation member 57 and the pad holder 52 are connected via a linear guide 58 extending in the vertical direction. When the pad holder 52 is pushed down by the air cylinder 53, the pressing pad 51 moves downward along the linear motion guide 58 and presses the polishing tape 38 against the edge portion of the wafer W. The pressing pad 51 is made of a resin such as PEEK (polyether ether ketone), a metal such as stainless steel, or a ceramic such as SiC (silicon carbide).

  The pressing pad 51 has a plurality of through holes 51a extending in the vertical direction, and a vacuum line 60 is connected to the through holes 51a. The vacuum line 60 is provided with a valve (not shown) so that a vacuum is formed in the through hole 51a of the pressing pad 51 by opening the valve. When a vacuum is formed in the through hole 51 a with the pressing pad 51 in contact with the upper surface of the polishing tape 38, the upper surface of the polishing tape 38 is held on the lower surface of the pressing pad 51. Note that the number of the through holes 51a of the pressing pad 51 may be one.

  The pad holder 52, the air cylinder 53, the holding member 55, the air cylinder 56, and the installation member 57 are accommodated in the box 62. The lower part of the pad holder 52 protrudes from the bottom of the box 62, and the pressing pad 51 is attached to the lower part of the pad holder 52. A position sensor 63 for detecting the vertical position of the pressing pad 51 is disposed in the box 62. The position sensor 63 is attached to the installation member 57. The pad holder 52 is provided with a dog 64 as a sensor target, and the position sensor 63 detects the vertical position of the pressing pad 51 from the vertical position of the dog 64.

  FIG. 17 is a view of the position sensor 63 and the dog 64 as viewed from above. The position sensor 63 includes a light projecting unit 63A and a light receiving unit 63B. When the dog 64 is lowered together with the pad holder 52 (and the pressing pad 51), a part of the light emitted from the light projecting unit 63A is blocked by the dog 64. Therefore, the position of the dog 64, that is, the position of the pressing pad 51 in the vertical direction can be detected from the amount of light received by the light receiving unit 63B. Note that the position sensor 63 shown in FIG. 17 is a so-called transmissive optical sensor, but other types of position sensors may be used.

  The polishing tape supply / recovery mechanism 70 includes a supply reel 71 for supplying the polishing tape 38 to the polishing head 50 and a recovery reel 72 for recovering the polishing tape 38 from the polishing head 50. The supply reel 71 and the recovery reel 72 are connected to tension motors 73 and 74, respectively. The tension motors 73 and 74 can apply a predetermined tension to the polishing tape 38 by applying a predetermined torque to the supply reel 71 and the recovery reel 72.

  A polishing tape feed mechanism 76 is provided between the supply reel 71 and the recovery reel 72. The polishing tape feeding mechanism 76 includes a tape feeding roller 77 that feeds the polishing tape 38, a nip roller 78 that presses the polishing tape 38 against the tape feeding roller 77, and a tape feeding motor 79 that rotates the tape feeding roller 77. Yes. The polishing tape 38 is sandwiched between the nip roller 78 and the tape feed roller 77. The polishing tape 38 is fed from the supply reel 71 to the collection reel 72 by rotating the tape feed roller 77 in the direction indicated by the arrow in FIG.

  The tension motors 73 and 74 and the tape feed motor 79 are installed on the base 81. The base 81 is fixed to the connection block 41B. The base 81 has two support arms 82 and 83 extending from the supply reel 71 and the recovery reel 72 toward the polishing head 50. A plurality of guide rollers 84A, 84B, 84C, 84D, and 84E that support the polishing tape 38 are attached to the support arms 82 and 83. The polishing tape 38 is guided by these guide rollers 84A to 84E so as to surround the polishing head 50.

  The extending direction of the polishing tape 38 is perpendicular to the radial direction of the wafer W when viewed from above. Two guide rollers 84D and 84E located below the polishing head 50 support the polishing tape 38 so that the polishing surface of the polishing tape 38 is parallel to the surface (upper surface) of the wafer W. Further, the polishing tape 38 between the two guide rollers 84D and 84E extends in parallel to the tangential direction of the wafer W. A gap is formed between the polishing tape 38 and the wafer W in the vertical direction.

  The polishing apparatus further includes a tape edge detection sensor 100 that detects the position of the edge of the polishing tape 38. The tape edge detection sensor 100 is a transmissive optical sensor, similar to the position sensor 63 described above. The tape edge detection sensor 100 includes a light projecting unit 100A and a light receiving unit 100B. The light projecting unit 100A is fixed to the installation base 27 as shown in FIG. 12, and the light receiving unit 100B is fixed to the base plate 21 that forms the polishing chamber 22, as shown in FIG. The tape edge detection sensor 100 is configured to detect the position of the edge of the polishing tape 38 from the amount of light received by the light receiving unit 100B.

  When polishing the wafer W, as shown in FIG. 18, the polishing head 50 and the polishing tape supply / recovery mechanism 70 are moved to predetermined polishing positions by the motors 42A and 42B and the ball screws 43A and 43B, respectively. The polishing tape 38 in the polishing position extends in the tangential direction of the wafer W when viewed from above the wafer W. The guide rollers 84D and 84E function as a polishing tape support mechanism that supports the polishing tape 38 in parallel with the surface of the wafer W in a state along the tangential direction of the wafer W.

  FIG. 19 is a schematic view of the pressing pad 51, the polishing tape 38, and the wafer W in the polishing position as viewed from the lateral direction. As shown in FIG. 19, the polishing tape 38 is positioned above the edge portion of the wafer W, and the pressing pad 51 is positioned above the polishing tape 38. The edge of the pressing pad 51 in the polishing position is coincident with the edge of the polishing tape 38. That is, the polishing head 50 and the polishing tape supply / recovery mechanism 70 are independently moved to the polishing position so that the edge of the pressing pad 51 and the edge of the polishing tape 38 coincide. FIG. 20 is a diagram showing a state where the polishing tape 38 is pressed against the wafer W by the pressing pad 51.

  The polishing tape 38 is an elongated strip-shaped polishing tool. The width of the polishing tape 38 is basically constant over its entire length, but there may be some variation in the width depending on the portion of the polishing tape 38. For this reason, there exists a possibility that the position of the edge part of the polishing tape 38 in a grinding | polishing position may differ for every wafer. On the other hand, the position of the pressing pad 51 in the polishing position is always constant. Therefore, in order to align the edge of the polishing tape 38 with the edge of the pressing pad 51, the position of the edge of the polishing tape 38 is detected by the above-described tape edge detection sensor 100 before being moved to the polishing position.

  FIG. 22A to FIG. 22C are diagrams for explaining the operation when the edge of the polishing tape 38 is detected. Prior to the polishing of the wafer W, the polishing tape 38 is moved from the retracted position shown in FIG. 22A to the tape edge detection position shown in FIG. At the tape edge detection position, the tape edge detection sensor 100 detects the position of the edge of the polishing tape 38 on the wafer side. Then, as shown in FIG. 22C, the polishing tape 38 is moved to the polishing position so that the edge of the polishing tape 38 coincides with the edge of the pressing pad 51. Since the polishing tape 38 can move independently of the polishing head 50, the polishing tape 38 can be moved by a distance that can vary depending on the width of the polishing tape 38.

  The position of the edge of the pressing pad 51 at the polishing position is stored in advance in the polishing control unit 11 (see FIG. 9). Therefore, the polishing control unit 11 causes the edge of the polishing tape 38 to coincide with the edge of the pressing pad 51 from the detected position of the edge of the polishing tape 38 and the position of the edge of the pressing pad 51. The moving distance of the polishing tape 38 can be calculated. In this way, since the moving distance of the polishing tape 38 is determined based on the detected position of the edge of the polishing tape 38, the edge of the polishing tape 38 is always pressed regardless of the width variation of the polishing tape 38. It can be aligned with the edge of the pad 51.

  As shown in FIG. 21, the polishing tape 38 is pressed against the edge portion of the wafer W by the pressing pad 51 in a state where a part of the polishing tape 38 is protruded radially inward from the inner edge portion of the pressing pad 51. May be.

  Next, the polishing operation of the polishing apparatus configured as described above will be described. The operation of the polishing apparatus described below is controlled by the polishing control unit 11 shown in FIG. The wafer W is held by the wafer holding unit 3 so that a film (for example, a device layer) formed on the surface thereof faces upward, and is further rotated around the center of the wafer W. A liquid (for example, pure water) is supplied to the center of the rotating wafer W from a liquid supply mechanism (not shown). The pressing pad 51 and the polishing tape 38 of the polishing head 50 are each moved to a predetermined polishing position as shown in FIG.

  FIG. 23A shows a view of the polishing tape 38 and the pressing pad 51 in the polishing position as viewed from the radial direction of the wafer W. FIG. The pressing pad 51 shown in FIG. 23A is lifted by the air cylinder 56 (see FIG. 16), and the pressing pad 51 is located above the polishing tape 38. Next, the operation of the air cylinder 56 is stopped and its piston rod is lowered, and the pressing pad 51 is lowered until its lower surface comes into contact with the upper surface of the polishing tape 38 as shown in FIG. In this state, a vacuum is formed in the through hole 51 a of the pressing pad 51 through the vacuum line 60, and the polishing tape 38 is held on the lower surface of the pressing pad 51. While holding the polishing tape 38, the pressing pad 51 is lowered by the air cylinder 53 (see FIG. 16). As shown in FIG. 23C, the pressing pad 51 sets the polishing surface of the polishing tape 38 to the peripheral edge of the wafer W. Press against the part with a predetermined polishing pressure. The polishing pressure is a pressing pressure that acts on the peripheral edge of the wafer W from the polishing tape 38. This polishing pressure can be adjusted by the pressure of the gas supplied to the air cylinder 53.

  As shown in FIG. 4, the pressing pad 51 during polishing is at a position shifted by a predetermined distance in the tangential direction from a preset origin position. The polishing tape 38 is pressed against the wafer W by the pressing pad 51 at the shifted position, and the edge portion of the wafer W is polished. As can be seen from FIG. 4, when the position of the pressing pad 51 is shifted in the tangential direction of the wafer W, the contact area (contact length) between the inner region of the wafer edge portion and the polishing tape 38 is not changed, and the outer side of the wafer edge portion is changed. The contact area between the region and the polishing tape 38 can be reduced. Therefore, a flat horizontal surface can be formed at the edge portion of the wafer W.

  The edge portion of the wafer W is polished by sliding contact between the rotating wafer W and the polishing tape 38. In order to increase the polishing rate of the wafer W, the polishing tape 38 and the pressing pad 51 may be swung along the tangential direction of the wafer W by the polishing unit moving mechanism (tangential moving mechanism) 30 during polishing of the wafer W. . During polishing, a liquid (for example, pure water) is supplied to the central portion of the rotating wafer W, and the wafer W is polished in the presence of water. The liquid supplied to the wafer W spreads over the entire upper surface of the wafer W due to centrifugal force, thereby preventing polishing dust from adhering to the device formed on the wafer W. As described above, during polishing, the polishing tape 38 is held on the pressing pad 51 by vacuum suction, so that the positions of the polishing tape 38 and the pressing pad 51 are prevented from shifting. Therefore, the polishing position and the polishing shape can be stabilized. Furthermore, even if the polishing pressure is increased, the polishing tape 38 and the pressing pad 51 are not displaced from each other, so that the polishing time can be shortened.

  The position of the pressing pad 51 during polishing of the wafer W in the vertical direction is detected by the position sensor 63. Therefore, the polishing end point can be detected from the vertical position of the pressing pad 51. For example, the polishing of the edge portion of the wafer W can be completed when the vertical position of the pressing pad 51 reaches a predetermined target position. This predetermined target position is determined according to the target polishing amount.

  When the polishing of the wafer W is completed, the supply of gas to the air cylinder 53 is stopped, whereby the pressing pad 51 is raised to the position shown in FIG. At the same time, the vacuum suction of the polishing tape 38 is stopped. Further, the pressing pad 51 is raised to the position shown in FIG. Then, the polishing head 50 and the polishing tape supply / recovery mechanism 70 are moved to the retracted position shown in FIG. The polished wafer W is raised by the wafer holding unit 3 and carried out of the polishing chamber 22 by a hand of a transfer mechanism (not shown). Before the polishing of the next wafer starts, the polishing tape 38 is fed from the supply reel 71 to the recovery reel 72 by a predetermined distance by the tape feeding mechanism 76. Thus, the new polishing surface is used for polishing the next wafer. When it is estimated that the polishing tape 38 is clogged with polishing scraps, the polished wafer W may be polished again with a new polishing surface after the polishing tape 38 has been fed a predetermined distance. The clogging of the polishing tape 38 can be estimated from, for example, the polishing time and the polishing pressure. The wafer W may be polished while the polishing tape 38 is fed at a predetermined speed by the tape feeding mechanism 76. It is also possible to feed the polishing tape 38 in the longitudinal direction by the tape feeding mechanism 76 while holding the polishing tape 38 on the pressing pad 51 by vacuum suction. In some cases, the polishing tape 38 may not be held on the pressing pad 51 by vacuum suction.

  As shown in FIG. 24A, when the polishing pressure on the wafer W is increased, the wafer W is greatly bent by the polishing pressure of the pressing pad 51. As a result, as shown in FIG. The surface to be polished may be inclined. Therefore, in the embodiment shown in FIG. 25, a support stage 180 that supports the peripheral edge of the wafer W from below is provided in the wafer holding unit 3. Other configurations that are not specifically described are the same as those shown in FIG. The support stage 180 is fixed to the support stage base 181. The support stage base 181 is fixed to the upper end of the casing 12 and rotates integrally with the casing 12. Therefore, the support stage 180 rotates integrally with the casing 12 and the holding stage 4.

  The support stage 180 has an inverted truncated cone shape as shown in FIG. 26 in order to support the entire lower surface of the peripheral edge of the wafer W. The lower surface of the peripheral portion of the wafer W supported by the support stage 180 is a region including at least the bottom edge portion E2 shown in FIGS. 32 (a) and 32 (b). An annular upper surface 180 a of the support stage 180 constitutes a support surface that supports the lower surface of the peripheral edge of the wafer W. At the time of polishing the wafer W, the outermost peripheral end of the support stage 180 and the outermost peripheral end of the wafer W substantially coincide with each other.

  By using such a support stage 180, even if the pressing pad 51 presses the polishing tape 38 against the wafer W, the wafer W does not bend. Therefore, by polishing the edge portion of the wafer W with the polishing tape 38, a vertical surface and a horizontal surface can be formed on the edge portion of the wafer W. Further, since the support stage 180 supports the entire lower surface of the peripheral edge of the wafer W, the edge portion of the wafer W can be uniformly polished as compared with a conventional wafer support mechanism that supports only a part of the wafer. .

  Since the ball spline bearing 6 is disposed between the hollow shaft 5 and the casing 12, the hollow shaft 5 can move in the vertical direction with respect to the casing 12. Therefore, the holding stage 4 connected to the upper end of the hollow shaft 5 can move in the vertical direction relative to the casing 12 and the support stage 180. FIG. 27 shows a state in which the holding stage 4 and the wafer W held on the upper surface thereof are raised relative to the support stage 180.

  The polishing tape 38 may receive a load in the horizontal direction due to the effect of contact with the wafer W and the shape of the peripheral edge of the wafer W. As a result, the polishing tape 38 may escape to the outside of the wafer W. Therefore, as shown in FIG. 28, a tape stopper 185 that restricts the horizontal movement of the polishing tape 38 is provided on the pressing pad 51. The tape stopper 185 is disposed outside the polishing tape 38 in the radial direction of the wafer W, and restricts the movement of the polishing tape 38 to the outside. The tape stopper 185 arranged in this way can prevent the polishing tape 38 from escaping to the outside of the wafer W. Therefore, the polishing shape and polishing width of the wafer W can be stabilized.

  When the outward movement of the polishing tape 38 is received by the tape stopper 185, the polishing tape 38 may be distorted as shown in FIG. Therefore, in the embodiment shown in FIG. 30, a tape cover 186 is provided close to the polishing surface of the polishing tape 38 in order to prevent the polishing tape 38 from being distorted. The tape cover 186 is fixed to the tape stopper 185 and is disposed so as to cover most of the polishing surface of the polishing tape 38. The tape cover 186 is disposed below the polishing tape 38, and a minute gap dg is formed between the polishing surface of the polishing tape 38 and the upper surface of the tape cover 186. The polishing tape 38 is disposed between the pressing pad 51 and the tape cover 186. By providing such a tape cover 186, the polishing tape 38 is prevented from being distorted, and the polishing tape 38 can be kept flat. Therefore, the polishing shape and polishing width of the wafer W can be stabilized.

  As shown in FIG. 30, the polishing tape 38 is disposed in a space surrounded by the pressing pad 51, the tape stopper 185, and the tape cover 186. A gap h between the lower surface of the pressing pad 51 and the upper surface of the tape cover 186 is set to be larger than the thickness of the polishing tape 38. A gap dg between the polishing tape 38 and the tape cover 186 is smaller than the thickness of the wafer W.

  The inner side surface 186 a of the tape cover 186 is located outside the edge portion 51 b of the pressing pad 51 in the radial direction of the wafer W. Therefore, the polishing surface of the polishing tape 38 is exposed by the distance dw between the edge of the polishing tape 38 and the inner surface 186a of the tape cover 186. The polishing of the wafer W is performed on the exposed polished surface.

  In the structure shown in FIG. 30, since the tape stopper 185 receives a horizontal load acting on the polishing tape 38, the pressing pad 51 may move outward together with the polishing tape 38. Such movement of the pressing pad 51 makes the polishing shape and the polishing width unstable. Therefore, in the embodiment shown in FIG. 31, a movement restricting mechanism for restricting the outward movement of the pressing pad 51 is provided. The movement restriction mechanism includes a protrusion member 190 fixed to the pressing pad 51 and a side stopper 191 that restricts the movement of the protrusion member 190 in the horizontal direction. In the present embodiment, a plunger is used as the protruding member 190.

  The side stopper 191 is disposed outside the plunger (protruding member) 190 in the radial direction of the wafer W, and receives the movement of the plunger 190 to the outside. The side stopper 191 is fixed to the lower surface of the box 62 of the polishing head 50, and the position of the side stopper 191 is fixed. The plunger 190 and the side stopper 191 are disposed close to each other, and the gap dr between the plunger 190 and the side stopper 191 is 10 μm to 100 μm. According to such a configuration, when the pressing pad 51 receives a horizontal load from the polishing tape 38 and moves to the outside during polishing, the plunger 190 comes into contact with the side stopper 191, thereby the outside of the pressing pad 51 and the polishing tape 38. Movement to is restricted. Therefore, the polishing shape and polishing width of the wafer W can be stabilized.

  The embodiments shown in FIGS. 25 to 31 can be combined as appropriate. For example, FIG. 32 shows an example in which the support stage 180 shown in FIG. 25 and the polishing head 50 shown in FIG. 31 are combined. According to the configuration shown in FIG. 32, the wafer W is prevented from being bent, and the movement and distortion of the polishing tape 38 are prevented.

  Next, details of a polishing apparatus capable of executing the above-described embodiment of the polishing method shown in FIGS. 7 and 8 will be described. 33 is a plan view showing the polishing apparatus, and FIG. 34 is a longitudinal sectional view of the polishing apparatus shown in FIG. As shown in FIGS. 33 and 34, the polishing apparatus includes a polishing head assembly 111 that presses a polishing tape 38 against an edge portion of a wafer W to polish the edge portion, and a polishing tape 38 that is attached to the polishing head assembly 111. And a polishing tape supply / recovery mechanism 112 for supplying the same. The polishing head assembly 111 is disposed inside the polishing chamber 22, and the polishing tape supply / recovery mechanism 112 is disposed outside the polishing chamber 22.

  The polishing tape supply / recovery mechanism 112 includes a supply reel 124 that supplies the polishing tape 38 to the polishing head assembly 111, and a recovery reel 125 that recovers the polishing tape 38 used for polishing the wafer W. Motors 129 and 129 are connected to the supply reel 124 and the recovery reel 125, respectively (only the motor 129 connected to the supply reel 124 is shown in FIG. 33). Each of the motors 129 and 129 can apply a predetermined torque to the supply reel 124 and the recovery reel 125 and apply a predetermined tension to the polishing tape 38.

  The polishing head assembly 111 includes a polishing head 131 for bringing the polishing tape 38 into contact with the peripheral edge of the wafer W. The polishing tape 38 is supplied to the polishing head 131 so that the polishing surface of the polishing tape 38 faces the wafer W. The polishing tape 38 is supplied from the supply reel 124 to the polishing head 131 through the opening 20b provided in the partition wall 20, and the used polishing tape 38 is recovered into the recovery reel 125 through the opening 20b.

  The polishing head 131 is fixed to one end of an arm 135, and the arm 135 is configured to be rotatable around a rotation axis Ct parallel to the tangential direction of the wafer W. The other end of the arm 135 is connected to the motor 138 via pulleys p3 and p4 and a belt b2. When the motor 138 rotates clockwise and counterclockwise by a predetermined angle, the arm 135 rotates about the axis Ct by a predetermined angle. In the present embodiment, the motor 138, the arm 135, the pulleys p3 and p4, and the belt b2 constitute a tilt mechanism that tilts the polishing head 131 with respect to the surface of the wafer W.

  The tilt mechanism is mounted on the movable table 140. The moving table 140 is connected to a polishing unit moving mechanism (tangential moving mechanism) 30, and the polishing head 131 and the polishing tape 38 supported by the polishing head 131 are moved in the tangential direction of the wafer W by the polishing unit moving mechanism 30. It is movable. On the other hand, the polishing tape supply / recovery mechanism 112 is fixed to the base plate 21.

  FIG. 35 is an enlarged view of the polishing head 131 shown in FIG. As shown in FIG. 35, the polishing head 131 includes a pressing pad 51 that presses the polishing tape 38 against the edge portion of the wafer W, and an air cylinder 53 as a pressing mechanism that presses the pressing pad 51 toward the wafer W. . The polishing head 131 includes a tape feeding mechanism 151 that sends the polishing tape 38 from the supply reel 124 to the recovery reel 125. The polishing head 131 has a plurality of guide rollers 153A, 153B, 153C, 153D, 153E, 153F, and 153G that guide the traveling direction of the polishing tape 38.

  The tape feeding mechanism 151 provided in the polishing head 131 includes a tape feeding roller 151a, a nip roller 151b, and a motor 151c that rotates the tape feeding roller 151a. The motor 151c is provided on the side surface of the polishing head 131, and a tape feed roller 151a is attached to the rotating shaft of the motor 151c. The nip roller 151b is disposed adjacent to the tape feed roller 151a. The nip roller 151b is supported by a mechanism (not shown) so as to generate a force in a direction indicated by an arrow NF in FIG. 35 (a direction toward the tape feed roller 151a), and is configured to press the tape feed roller 151a. .

  When the motor 151c rotates in the direction of the arrow shown in FIG. 35, the tape feed roller 151a rotates to feed the polishing tape 38 from the supply reel 124 to the collection reel 125 via the polishing head 131. The nip roller 151b is configured to be able to rotate around its own axis.

  The pressing pad 51 is disposed on the back side of the polishing tape 38, and the air cylinder 53 moves the pressing pad 51 toward the peripheral edge of the wafer W. By controlling the pressure of the gas supplied to the air cylinder 53, the polishing pressure on the wafer W is adjusted.

  When the edge portion of the wafer W is polished, the polishing head 131 is tilted upward by the tilt mechanism described above until the wafer pressing surface of the pressing pad 51 becomes parallel to the surface of the wafer W, as shown in FIG. Then, the polishing tape 38 is pressed against the edge portion of the wafer W by the pressing pad 51 to polish the edge portion. The two guide rollers 153D and 153E arranged so as to sandwich the pressing pad 51 are such that the polishing tape 38 extends along the center line CL (see FIG. 8) of the wafer W when viewed from above the wafer W. A polishing tape support mechanism for supporting the polishing tape 38 is configured.

  As shown in FIG. 8, the pressing pad 51 during polishing is at a position shifted from the preset origin position by a predetermined distance in the tangential direction. The polishing tape 38 is pressed against the wafer W by the pressing pad 51 at the shifted position, and the edge portion of the wafer W is polished. As can be seen from FIG. 8, when the position of the pressing pad 51 is shifted in the tangential direction of the wafer W, the contact area (contact length) between the inner region of the wafer edge portion and the polishing tape 38 is not changed, and the outer side of the wafer edge portion is changed. The contact area between the region and the polishing tape 38 can be reduced. Therefore, a flat horizontal surface can be formed at the edge portion of the wafer W.

  The embodiment described above is described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.

DESCRIPTION OF SYMBOLS 3 Wafer holding part 4 Holding stage 11 Polishing control part 25 Polishing unit 27 Installation stand 30 Polishing unit moving mechanism (tangential direction moving mechanism)
38 Abrasive tape 40A, 40B Linear motion guide 45 Radial direction moving mechanism (first moving mechanism)
46 Tape moving mechanism (second moving mechanism)
50 Polishing head 51 Press pad 52 Pad holder 53 Air cylinder 54 Linear motion guide 56 Air cylinder 59 Vertical movement mechanism 60 Vacuum line 63 Position sensor 64 Dog 70 Polishing tape supply and recovery mechanism 71 Supply reel 72 Recovery reel 73, 74 Tension motor 76 Tape Feed mechanism 82, 83 Support arm 84A, 84B, 84C, 84D, 84E Guide roller 100 Tape edge detection sensor 111 Polishing head assembly 112 Polishing tape supply and recovery mechanism 124 Supply reel 125 Recovery reel 131 Polishing heads 153A to 153G Guide roller 180 Support Stage 181 Support stage base 185 Tape stopper 186 Tape cover 190 Plunger 191 Side stopper W Wafer

Claims (7)

In a polishing apparatus for polishing an edge portion of a substrate,
A wafer holder for holding and rotating the substrate;
A pressing pad for pressing a polishing tape against the edge of the substrate;
A tangential moving mechanism connected to the pressing pad and moving the pressing pad in a tangential direction of the substrate;
A polishing controller for controlling the operation of the polishing apparatus,
The polishing control unit is configured such that, before the pressing pad presses the polishing tape against the edge portion of the substrate, the tangential movement mechanism causes the pressing pad to move to the origin position on the center line extending in the radial direction from the center of the substrate. From a position shifted by a predetermined distance in the tangential direction of the substrate, and disposed above the edge portion of the substrate,
A polishing apparatus characterized by polishing the edge portion of the substrate by pressing the polishing tape against the edge portion of the substrate with the pressing pad at the shifted position . The polishing apparatus according to claim 1 , wherein the tangential direction is perpendicular to the center line. Said predetermined distance, the polishing apparatus according to claim 1 or 2, wherein the said pressure pad along the tangential direction is less than the length of the half. The polishing apparatus according to any one of claims 1 to 3 , wherein the polishing tape extends in the tangential direction when viewed from above the substrate. In a state in which a part of the polishing tape protrudes from the edge of the pressing pad, the pressing pad does not protrude from the region protruding from the edge of the pressing pad and from the edge of the pressing pad. The polishing apparatus according to claim 4 , wherein both regions are pressed against an edge portion of the substrate. The polishing tape, when viewed from above the substrate, the polishing apparatus according to any one of claims 1 to 3, characterized in that extending along the center line. In a polishing apparatus for polishing an edge portion of a substrate,
A wafer holder for holding and rotating the substrate;
A pressing pad for pressing a polishing tape against the edge of the substrate;
A tangential moving mechanism connected to the pressing pad and moving the pressing pad in a tangential direction of the substrate;
The polishing tape extends in the tangential direction when viewed from above the substrate;
Wherein the edges of the pressure pad in a state that is aligned with the edge of the polishing tape, characterized in that the edges of the pressure pad presses the polishing tape to the edge portion of the substrate Migaku Ken apparatus.

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