JP2017157646A - Polishing method and polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing method capable of preventing breakdown or damage of a polishing object, which may occur when the polishing object is left out on the polished surface after completion of polishing.SOLUTION: A top ring 20 has a top ring body 60, a holding mechanism for holding a semiconductor wafer W on the lower surface of the top ring body 60, and a stopper 64 placed on the radial outside of the wafer W, and movable up and down independently from the top ring body 60. While rotating a polishing table 12, the wafer W is pressed against an abrasive pad 10 by means of the top ring 20, thus polishing the surface of the wafer W. Polishing conditions of the wafer W are adjusted by pressing a retainer ring 62, placed between the wafer W and stopper 64, against the abrasive pad 10, while polishing. After polishing the surface of the wafer W, the top ring body 60 is moved upward from the abrasive pad 10, while bringing the lower surface of the stopper 64 into contact with the abrasive pad 10 for a predetermined time, in a state where the holding mechanism is actuated.SELECTED DRAWING: Figure 4E

Description

  The present invention relates to a polishing method and a polishing apparatus, and more particularly to a polishing method and a polishing apparatus for polishing a polishing object such as a semiconductor wafer and flattening the surface thereof.

  With the recent high integration of semiconductor devices, it is important to planarize the surface of the semiconductor device in the semiconductor device manufacturing process. Chemical mechanical polishing (CMP) is known as one method for flattening the surface of such a semiconductor wafer. In this type of polishing apparatus, as shown in FIG. 1A, the semiconductor wafer W is held on the lower surface of the top ring 500, and the semiconductor wafer W is pressed against the polishing pad 502 on the polishing table 501 with a predetermined pressure. At this time, a polishing liquid 506 containing slurry or the like is supplied from the liquid supply nozzle 504 onto the polishing pad 502. The polishing table 501 and the top ring 500 are rotated independently of each other to cause relative movement between the polishing pad 502 and the top ring 500. As a result, the semiconductor wafer W is brought into sliding contact with the polishing pad 502, and the surface of the semiconductor wafer W is polished flat and mirror-like by the mechanical action and the chemical action of the polishing liquid 506 on the polishing pad 502.

  When the polishing of the semiconductor wafer W is completed, the semiconductor wafer W is attracted to the lower surface of the top ring 500 and the top ring 500 is raised as shown in FIG. 1B. As a result, the semiconductor wafer W is peeled off from the polishing pad 502, and the polished semiconductor wafer W is transferred to the next step. However, when the top ring 500 is raised, a liquid such as a polishing liquid, pure water, or a cleaning liquid exists between the polishing pad 502 and the semiconductor wafer W, and therefore, between the polishing pad 502 and the semiconductor wafer W. Adsorption force is generated in Therefore, when the top ring 500 is raised so as to peel the semiconductor wafer W from the polishing pad 502, the semiconductor wafer W has an adsorption force between the polishing pad 502 and the semiconductor wafer W as shown in FIG. 1C. In some cases, it may be left behind on the polishing pad 502 without resisting.

  When the semiconductor wafer W is left on the polishing pad 502 in this way, as shown in FIG. 1D, the semiconductor wafer W slides out of the polishing table 501 due to the centrifugal force generated by the rotation of the polishing table 501 and is set around the semiconductor wafer W. The semiconductor wafer W collides with another component (for example, a dresser) (slipout). In such a case, the semiconductor wafer W is broken or damaged, and the yield in the manufacturing process is lowered.

  In order to prevent this, an attempt has been made to adsorb the semiconductor wafer W while reducing the flow rate of the polishing liquid supplied onto the polishing pad 502 when the semiconductor wafer W is peeled off (for example, Patent Document 1). This method cannot completely prevent the semiconductor wafer W from being left on the polishing pad 502. Further, for example, it is conceivable that the rotation of the polishing table 501 is stopped by detecting that the semiconductor wafer W is left on the polishing table 501, but the polishing is performed after detecting that the semiconductor wafer W is left behind. Even if the rotation of the table 501 is stopped, the semiconductor wafer W slides out of the polishing table 501 until the polishing table 501 is completely stopped, so that it is difficult to avoid collision with the components installed around.

JP 2009-178800 A

  The present invention has been made in view of such problems of the prior art, and can prevent damage or damage to the polishing object that may occur when the polishing object is left behind on the polishing surface after polishing. An object of the present invention is to provide a polishing method and a polishing apparatus.

  According to the first aspect of the present invention, there is provided a polishing method capable of preventing breakage or damage of a polishing object even if the polishing object is left on the polishing surface after completion of polishing. In this method, the top ring body, a holding mechanism for holding the object to be polished on the lower surface of the top ring body, and the top ring disposed on the radially outer side of the object to be polished held by the holding mechanism. A top ring having a stopper that can move up and down independently of the main body is prepared. While rotating the polishing surface, the object to be polished is pressed against the polishing surface by the top ring to polish the surface of the object to be polished. After polishing the surface of the object to be polished, the top ring body is moved upward from the polishing surface while the holding mechanism is operated and the lower surface of the stopper is in contact with the polishing surface for a predetermined time. Let

  According to this method, even if the object to be polished is left on the polishing surface for some reason after polishing the surface of the object to be polished, the top ring main body moves upward from the polishing surface for a predetermined time. Since the stopper remains in contact with the polishing surface, the stopper is positioned so as to surround the object to be polished on the polishing surface. Accordingly, even if the object to be polished slides outward due to the centrifugal force due to the rotation of the polishing surface, the movement of the object to be polished is blocked by the stopper, and the object to be polished collides with a component (such as a dresser) installed around the object. There is nothing. For this reason, breakage or damage of the object to be polished can be prevented, and a decrease in yield in the manufacturing process can be prevented.

  Here, when the top ring body is moved upward from the polishing surface, it is determined whether the object to be polished is held on the lower surface of the top ring body, and the object to be polished is the top ring body The rotation of the polishing surface may be stopped when it is determined that the polishing surface is not held on the lower surface. In this way, by stopping the rotation of the polishing surface when the object to be polished is left on the polishing surface, the centrifugal force due to the rotation of the polishing surface is reduced, so that the object can be effectively damaged or damaged. Can be prevented.

  A suction mechanism using fluid pressure may be used as the holding mechanism of the top ring. In this case, when determining whether or not the object to be polished is held on the lower surface of the top ring body, the pressure of the fluid used in the suction mechanism is measured, and the pressure of the fluid to be measured is measured. Based on the above, it may be determined whether the object to be polished is held on the lower surface of the top ring body.

  Moreover, it is preferable to form the lower end part of the internal peripheral surface of the said stopper with the material which has elasticity. Thereby, it is possible to absorb an impact when the object to be polished hits the stopper, and effectively prevent the object to be polished from being broken or damaged.

  For example, a retainer ring disposed between the object to be polished and the stopper is polished during the polishing of the surface of the object to be polished so that only the outer peripheral edge of the object is not polished. It is preferable to adjust the polishing conditions of the workpiece by pressing against the surface. In addition to this, or alternatively, during the polishing of the surface of the object to be polished, the polishing condition of the object to be polished may be adjusted by pressing the stopper against the polishing surface.

  According to the second aspect of the present invention, there is provided a polishing apparatus capable of preventing breakage or damage of an object to be polished even if the object to be polished is left on the polishing surface after completion of polishing. The polishing apparatus includes a polishing surface, a rotating mechanism that rotates the polishing surface, and a top ring that presses the object to be polished against the polishing surface and polishes the surface of the object to be polished. The top ring is disposed on the outer side in the radial direction of the object to be polished held by the holding mechanism, a holding mechanism for holding the object to be polished on the lower surface of the top ring body, and the top ring. A stopper that can move up and down independently of the top ring body is provided. The polishing apparatus includes a main body vertical movement mechanism that moves the top ring main body up and down, a stopper vertical movement mechanism that moves the stopper up and down independently of the top ring main body, at least the rotation mechanism, the holding mechanism, and the A main body vertical movement mechanism, and a controller that controls the operation of the stopper vertical movement mechanism. The controller is configured to move the top ring body upward from the polishing surface while keeping the lower surface of the stopper in contact with the polishing surface for a predetermined time while the holding mechanism is operated. The operation of the main body vertical movement mechanism and the stopper vertical movement mechanism is controlled.

  It is preferable that the polishing apparatus further includes a sensor that detects whether the object to be polished is held on the lower surface of the top ring body. In this case, the control unit preferably stops the rotation by the rotation mechanism when the sensor detects that the object to be polished is not held on the lower surface of the top ring body. The holding mechanism may be a suction mechanism that sucks the object to be polished to the lower surface of the top ring body using a fluid pressure, and the sensor controls the pressure of the fluid used in the suction mechanism. It may be a pressure sensor to measure.

  The lower end portion of the inner peripheral surface of the stopper is preferably formed of an elastic material. Thereby, it is possible to absorb an impact when the object to be polished hits the stopper, and effectively prevent the object to be polished from being broken or damaged.

  It is preferable that the top ring further includes a retainer ring that is disposed on the radially inner side of the stopper and can move up and down independently of the top ring body and the stopper. In this case, it is preferable that the polishing apparatus further includes a retainer ring vertical movement mechanism that moves the retainer ring up and down independently of the top ring body and the stopper. Moreover, it is preferable that the said control part is comprised so that the said retainer ring vertical movement mechanism may be controlled so that the said retainer ring may press the said grinding | polishing surface corresponding to the outer peripheral part of the said to-be-polished object. Moreover, it is preferable that the said control part controls the said stopper vertical movement mechanism so that the said stopper may press the said grinding | polishing surface corresponding to the outer peripheral part of the said to-be-polished object.

  According to the present invention, even if the object to be polished is left on the polishing surface for some reason after polishing the surface of the object to be polished, the top ring main body moves upward from the polishing surface for a predetermined time. Since the stopper remains in contact with the polishing surface, the stopper is positioned so as to surround the object to be polished on the polishing surface. Therefore, even if the object to be polished slides outward due to the centrifugal force due to the rotation of the polishing surface, the movement of the object to be polished is blocked by the stopper, and the object to be polished does not collide with the components installed around. For this reason, breakage or damage of the object to be polished can be prevented, and a decrease in yield in the manufacturing process can be prevented.

It is a schematic diagram which shows the structure of the conventional grinding | polishing apparatus. It is a schematic diagram for demonstrating the problem in the conventional grinding | polishing apparatus. It is a schematic diagram for demonstrating the problem in the conventional grinding | polishing apparatus. It is a schematic diagram for demonstrating the problem in the conventional grinding | polishing apparatus. It is a mimetic diagram showing the composition of the polish device in one embodiment of the present invention. It is a schematic diagram which shows the top ring in the grinding | polishing apparatus shown in FIG. It is a schematic diagram for demonstrating the grinding | polishing process by the grinding | polishing apparatus shown in FIG. It is a schematic diagram for demonstrating the grinding | polishing process by the grinding | polishing apparatus shown in FIG. It is a schematic diagram for demonstrating the grinding | polishing process by the grinding | polishing apparatus shown in FIG. It is a schematic diagram for demonstrating the grinding | polishing process by the grinding | polishing apparatus shown in FIG. It is a schematic diagram for demonstrating the grinding | polishing process by the grinding | polishing apparatus shown in FIG. It is a schematic diagram which shows the top ring of the grinding | polishing apparatus in other embodiment of this invention.

  Hereinafter, embodiments of a polishing apparatus according to the present invention will be described in detail with reference to FIGS. 2 to 5, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted. In FIGS. 2 to 5, the scale and dimensions of each component are exaggerated and some components may be omitted.

  FIG. 2 is a schematic diagram showing the configuration of the polishing apparatus 1 according to an embodiment of the present invention. As shown in FIG. 2, the polishing apparatus 1 includes a polishing table 12 having a polishing pad 10 affixed to an upper surface, and a top that holds a semiconductor wafer W as an object to be polished and presses the polishing pad 10 on the polishing table 12. The ring 20, the liquid supply nozzle 30 disposed above the polishing table 12, the top ring head 42 that can swing on a horizontal plane around the head shaft 40, and the operation of each component in the polishing apparatus 1 are controlled. And a control unit 91.

  The polishing table 12 is supported by a table shaft 14 that extends downward from the center of the polishing table 12. The surface of the polishing pad 10 affixed to the upper surface of the polishing table 12 constitutes a polishing surface for polishing the wafer W. The polishing table 12 is connected to a table motor (not shown) via a table shaft 14, and the polishing table 12 rotates around the table shaft 14 by driving the table motor. Thus, the table shaft 14 and the table motor constitute a rotating mechanism that rotates the polishing surface.

  FIG. 3 is a schematic diagram showing the top ring 20. As shown in FIG. 3, the top ring 20 includes a top ring main body 60 connected to the top ring shaft 22 (FIG. 2), and an annular retainer ring located on the radially outer side of the wafer W held by the top ring 20. 62, an annular stopper 64 disposed radially outside the retainer ring 62, and an elastic film 66 attached to the lower surface of the top ring body 60. The top ring body 60 is connected to the lower end of the top ring shaft 22 that extends vertically. The top ring main body 60, the retainer ring 62, and the stopper 64 are configured to rotate integrally with the rotation of the top ring shaft 22. As will be described later, the top ring head 42 is provided with a mechanism for rotating and moving the top ring shaft 22 up and down, and the top ring 20 (the top ring body 60) is rotated and moved up and down. Rotate and move up and down.

  Returning to FIG. 2, the top ring head 42 is provided with a main body vertical movement mechanism 43 that moves the top ring main body 60 of the top ring 20 up and down by moving the top ring shaft 22 up and down. The main body vertical movement mechanism 43 includes a bridge 45 that rotatably supports the top ring shaft 22 via a bearing 44, a ball screw 46 attached to the bridge 45, a column 47 fixed to the top ring head 42, a column A pedestal 48 supported by the pedestal 47 and an AC servomotor 49 installed on the pedestal 48 are provided.

  The ball screw 46 includes a screw shaft 46A connected to the AC servomotor 49, and a nut 46B fixed to the bridge 45 and screwed to the screw shaft 46A. The top ring shaft 22 is configured to move up and down integrally with the bridge 45. In such a configuration, when the AC servomotor 49 is driven, the screw shaft 46A rotates, and the nut 46B moves up and down accordingly. As a result, the bridge 45 and the top ring shaft 22 move up and down with respect to the top ring head 42, and the top ring body 60 attached to the lower end of the top ring shaft 22 moves up and down.

  The top ring shaft 22 is connected to the rotary cylinder 50 via a key (not shown). The rotary cylinder 50 has a timing pulley 51 on the outer periphery. A top ring motor 52 is fixed on the top ring head 42, and a timing pulley 53 is connected to a rotation shaft of the top ring motor 52. A timing belt 54 is bridged between the timing pulley 51 and the timing pulley 53. In such a configuration, when the top ring motor 52 is driven, the rotary cylinder 50 and the top ring shaft 22 are rotated together via the timing pulley 53, the timing belt 54, and the timing pulley 51, and accordingly the top ring is rotated. The main body 60 rotates around the top ring shaft 22.

  When polishing the wafer W, the top ring motor 52 is driven to rotate the top ring 20, and the table motor is driven to rotate the polishing table 12. A liquid 32 such as a polishing liquid is supplied from the liquid supply nozzle 30 onto the polishing pad 10 of the polishing table 12. Then, the AC servo motor 49 is driven to lower the top ring 20 and press the wafer W held on the lower surface of the top ring 20 against the polishing pad 10 on the polishing table 12.

  As shown in FIG. 3, the elastic film 66 attached to the lower surface of the top ring main body 60 has a plurality of partition walls 67. The elastic film 66 is made of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, and silicon rubber. By these partition walls 67, the lower surface of the top ring main body 60 has a center chamber 71 located at the center, a ripple chamber 72 located radially outside the center chamber 71, and an outer chamber 73 located radially outside the ripple chamber 72. And the edge chamber 74 located in the radial direction outer side of the outer chamber 73 is formed. The ripple chamber 72 is formed with a suction hole 72A that opens downward.

  The retainer ring 62 is disposed so as to surround the outer peripheral edge of the wafer W when the wafer W is held on the lower surface of the top ring main body 60, and is connected to the top ring main body 60 by an elastic film 68. A retainer ring chamber 75 is formed inside the elastic film 68. The elastic film 68 is formed of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, or silicon rubber.

  The stopper 64 is disposed so as to surround the outer peripheral edge of the retainer ring 62, and is connected to the top ring body 60 by an elastic film 69. A stopper chamber 76 is formed inside the elastic film 69. The elastic film 69 is formed of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, and silicon rubber.

  As shown in FIG. 3, the top ring 20 has a flow path 81 communicating with the center chamber 71, a flow path 82 communicating with the ripple chamber 72, a flow path 83 communicating with the outer chamber 73, and an edge chamber. A flow path 84 that communicates with 74, a flow path 85 that communicates with the retainer ring chamber 75, and a flow path 86 that communicates with the stopper chamber 76 are formed. These flow paths 81 to 86 are shown in FIG. As described above, it extends to the pressure adjusting unit 90 via the rotary joint 24 attached to the upper end of the top ring shaft 22. The pressure adjusting unit 90 is configured to adjust the pressure of each of the flow paths 81 to 86 using the pressure of a compressed air source, a vacuum source, the atmosphere, or the like based on a command from the control unit 91. .

  In the present embodiment, the pressure adjusting unit 90 connects the ripple chamber 72 to a vacuum source via the flow path 82, thereby forming a negative pressure in the suction hole 72 </ b> A of the ripple chamber 72, so that the wafer W is attached to the top ring body 60. Suction to the bottom of the. Thus, in the present embodiment, a suction mechanism that sucks the wafer W to the lower surface of the top ring body 60 is configured by the ripple chamber 72 in which the pressure adjusting unit 90, the flow path 82, and the suction hole 72A are formed.

  In addition, the pressure adjusting unit 90 can increase or decrease the volume of the retainer ring chamber 75 by adjusting the pressure of the fluid supplied to the retainer ring chamber 75 via the flow path 85. The ring 62 can be moved up and down independently of the top ring body 60 and the stopper 64. That is, a retainer ring up-and-down moving mechanism that moves the retainer ring 62 up and down independently of the top ring body 60 and the stopper 64 is configured by the elastic film 68 that forms the pressure adjusting unit 90, the flow path 85, and the retainer ring chamber 75. .

  In addition, the pressure adjusting unit 90 can increase or decrease the volume of the stopper chamber 76 by adjusting the pressure of the fluid supplied to the stopper chamber 76 via the flow path 86, and thereby the stopper 64 can be reduced. The top ring body 60 and the retainer ring 62 can move up and down independently. That is, a stopper vertical movement mechanism for moving the stopper 64 up and down independently of the top ring main body 60 and the retainer ring 62 is configured by the elastic film 69 forming the pressure adjusting unit 90, the flow path 86, and the stopper chamber 76.

  Next, a method for polishing the wafer W using the polishing apparatus 1 having such a configuration will be described. First, at the start of polishing, the top ring head 42 is swung around the head shaft 40, and the top ring 20 is moved to the position of the pusher 100 that delivers the wafer W as shown in FIG. 4A. When the pusher 100 delivers the wafer W between the top ring 20 and the pusher 100, the support portion 102 that can be fitted to the outer peripheral surface of the top ring 20 for centering with the top ring 20. A pusher stage 104 for supporting the wafer W, an air cylinder (not shown) for moving the pusher stage 104 up and down, and an air cylinder (not shown) for moving the pusher stage 104 and the support portion 102 up and down. ).

  When the wafer W is transferred between the top ring 20 and the pusher 100, the top ring 20 moves upward of the pusher 100, and then the pusher stage 104 and the support unit 102 of the pusher 100 are raised to move the support unit 102. The top ring 20 and the pusher 100 are centered by fitting with the outer peripheral surface of the top ring 20. Then, the pusher stage 104 on which the wafer W is placed is raised, and the upper surface of the wafer W is brought into contact with the elastic film 66 of the top ring 20. At this time, the pressure adjustment unit 90 connects the ripple chamber 72 to the vacuum source via the flow path 82 in accordance with a command from the control unit 91. Thereby, a negative pressure is formed in the suction hole 72A, and the wafer W is vacuum-sucked on the lower surface of the elastic film 66.

  Next, the top ring 20 is moved above the polishing table 12 by the swing of the top ring head 42 and the vertical movement of the top ring shaft 22, and the top ring 20 is lowered and vacuum-sucked as shown in FIG. 4B. Is brought into contact with the polishing pad 10. At this time, the polishing table 12 and the top ring 20 are rotated, and the polishing liquid is supplied onto the polishing pad 10 from the liquid supply nozzle 30. When the wafer W is pressed against the polishing pad 10 by the top ring 20, the wafer W is brought into sliding contact with the polishing pad 10, and the surface of the wafer W is flattened by the mechanical action and chemical action of the polishing liquid on the polishing pad 10. And it is polished into a mirror surface.

  Here, when the relative pressing force between the wafer W being polished and the polishing pad 10 is not uniform over the entire surface of the wafer W, the polishing is insufficient or excessive depending on the pressing force acting on each part of the wafer W. Polishing occurs. Therefore, in the present embodiment, the pressure adjusting unit 90 applies a predetermined pressure to the center chamber 71, the ripple chamber 72, the outer chamber 73, and the edge chamber 74 via the flow paths 81 to 84 in accordance with a command from the control unit 91. Then, the elastic film 66 is expanded to press the wafer W against the polishing pad 10. Thus, the pressing force for pressing the wafer W against the polishing pad 10 is adjusted for each portion corresponding to the center chamber 71, the ripple chamber 72, the outer chamber 73, and the edge chamber 74, and the surface of the wafer W becomes in a desired state. So that it is polished.

  Further, since the polishing pad 10 has elasticity, the pressing force applied to the outer peripheral edge portion of the wafer W being polished becomes non-uniform, and only the outer peripheral edge portion of the wafer W may be often polished. In order to prevent such a situation, the pressure adjusting unit 90 supplies a fluid with a predetermined pressure to the retainer ring chamber 75 via the flow path 85 in accordance with a command from the control unit 91 to inflate the elastic film 68. . As a result, the retainer ring 62 is pressed against the portion of the polishing pad 10 located on the outer peripheral edge side of the wafer W with a predetermined pressure, so that only the outer peripheral edge portion of the wafer W is not polished much. Is adjusted.

  As will be described later, the stopper 64 protects the wafer W left on the polishing pad 10 when the wafer W is peeled off from the polishing pad 10. The stopper 64 is also similar to the retainer ring 62 described above. You may give the function of. That is, it is conceivable that the retainer ring 62 receives a horizontal force from the wafer W during polishing, and the retainer ring 62 is inclined or locally deformed. The portion of the polishing pad 10 located on the outer peripheral edge side of the wafer W cannot be pressed with a desired pressure. Accordingly, the portion of the polishing pad 10 located on the outer peripheral edge side of the wafer W is also pressed by the stopper 64 to suppress the inclination and local deformation of the retainer ring 62 with respect to the polishing pad 10, while only the outer peripheral edge portion of the wafer W. You may adjust the grinding | polishing conditions of the wafer W so that it may not polish much.

  Specifically, the pressure adjusting unit 90 supplies a fluid having a predetermined pressure to the stopper chamber 76 via the flow path 86 in accordance with a command from the control unit 91 to inflate the elastic film 69. As a result, the stopper 64 is pressed against the portion of the polishing pad 10 located on the outer peripheral edge side of the wafer W with a predetermined pressure. The pressing by the retainer ring 62 and the pressing by the stopper 64 can be performed independently. For example, the pressing force by the stopper 64 may be lower than the pressing force by the retainer ring 62. In this way, the horizontal force acting on the retainer ring 62 does not act on the stopper 64, and the inclination of the stopper 64 relative to the polishing pad 10 and local deformation can be suppressed. Therefore, the portion of the polishing pad 10 located on the outer peripheral edge side of the wafer W can be pressed with a desired pressure by the retainer ring 62 and the stopper 64.

  After the polishing of the wafer W is completed, the pressure adjusting unit 90 connects the ripple chamber 72 to the vacuum source via the flow path 82 in accordance with a command from the control unit 91. Thereby, a negative pressure is formed in the suction hole 72A, and the wafer W is vacuum-sucked on the lower surface of the elastic film 66. Thereafter, the top ring main body 60 is raised and the wafer W is peeled off from the polishing pad 10. At this time, the pressure adjusting unit 90 follows the command from the control unit 91 for a predetermined time (for example, until the top ring main body 60 rises to a predetermined height) via the flow path 86 to the stopper chamber 76. Is supplied with a fluid having a predetermined pressure, and the elastic membrane 69 is expanded as shown in FIG. 4C. As a result, the stopper 64 is pressed against (in contact with) the polishing pad 10.

  After the predetermined time has elapsed, the pressure adjusting unit 90 stops supplying the pressure fluid to the stopper chamber 76. As a result, as shown in FIG. 4D, the swelled elastic film 69 returns to its original state, and the stopper 64 rises away from the polishing pad 10. Thereafter, the top ring 20 is moved, for example, to the position of the pusher 100 or a transfer robot (not shown) by the vertical movement of the top ring shaft 22 and the swing of the top ring head 42, and the polished wafer W is moved to the pusher 100 or the like. Hand it over to the transfer robot.

  As described above, after polishing the wafer W, the wafer W is vacuum-sucked to the lower surface of the elastic film 66, and the top ring body 60 is raised. At this time, it is assumed that the wafer W is left on the polishing pad 10 without resisting the adsorption force generated between the polishing pad 10 and the wafer W. Even in such a case, as described above, the stopper 64 remains in contact with the polishing pad 10 for a predetermined time after the top ring body 60 is lifted from the polishing pad 10, so that FIG. As shown, the stopper 64 is positioned so as to surround the wafer W on the polishing pad 10. Therefore, even if the wafer W starts to slide outward due to the centrifugal force generated by the rotation of the polishing table 12, the movement of the wafer W outward in the radial direction is blocked by the stopper 64, and the wafer is placed on the surrounding components (for example, a dresser). W will not collide. As described above, in the present embodiment, even when the wafer W is left on the polishing pad 10, the wafer W does not collide with components installed around it, and the breakage or damage of the wafer W is prevented. Can do. Therefore, it is possible to prevent a decrease in yield in the manufacturing process.

  At this time, it is detected whether or not the wafer W is left on the polishing pad 10, that is, whether or not the wafer W is dropped from the lower surface of the elastic film 66, and the wafer W is left on the polishing pad 10. In some cases, an alarm may be issued, the rotation of the polishing table 12 by the table motor may be stopped, or the operation of another transport mechanism may be stopped. For example, when a pressure sensor 95 (see FIG. 3) for measuring the pressure of the fluid in the flow path 82 connected to the ripple chamber 72 is provided, and the pressure sensor 95 detects an increase in pressure in the flow path 82. It may be determined that the wafer W has dropped out. Alternatively, it may be detected that the wafer W is left on the polishing pad 10 by an eddy current sensor (not shown) embedded in the polishing table 12, or the intensity of reflected light of the light irradiated on the polishing pad 10. It may be detected that the wafer W is left on the polishing pad 10 by a sensor that detects the above.

  When it is determined that the wafer W is left on the polishing pad 10, the wafer W is picked up using a hand (not shown) for holding the wafer W and mounted on a load unit (not shown). It may be collected in an open cassette, a SMIF (Standard Manufacturing Interface) pod, or a FOUP (Front Opening Unified Pod), or may be moved to the next transport device. For example, these processes are performed by an operator operating an operation panel. Thereafter, the operator may cancel the alarm issued due to the dropping of the wafer W and resume processing of another wafer.

  Further, as shown in FIG. 5, the portion of the wafer W left on the polishing pad 10 is in contact with the stopper 64, that is, the lower end portion 64A of the inner peripheral surface of the stopper 64 is made of an elastic material such as resin or rubber. And the impact when the wafer W hits the stopper 64 may be absorbed. Further, the entire stopper 64 may be formed of a material that absorbs such an impact.

  The rotation mechanism, the main body vertical movement mechanism 43, the retainer ring vertical movement mechanism, and the stopper vertical movement mechanism described above are merely examples, and these mechanisms can be configured using other known techniques. In the above-described embodiment, the wafer W is held on the lower surface of the top ring body 60 by using a suction mechanism that sucks the wafer W onto the lower surface of the top ring body 60. Other known mechanisms can also be used as a holding mechanism for holding in the case.

  In the above-described embodiment, the example in which the retainer ring 62 is disposed on the radially inner side of the stopper 64 has been described. However, the retainer ring 62 may be omitted. In this case, as described above, the portion of the polishing pad 10 positioned on the outer peripheral edge side of the wafer W is pressed by the stopper 64 during polishing so that only the outer peripheral edge portion of the wafer W is not polished much. It is preferable to adjust the polishing conditions of the wafer W.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and it goes without saying that the present invention may be implemented in various forms within the scope of the technical idea.

W Semiconductor wafer (object to be polished)
1 Polishing device 10 Polishing pad (Polished surface)
DESCRIPTION OF SYMBOLS 12 Polishing table 14 Table shaft 20 Top ring 22 Top ring shaft 24 Rotary joint 30 Liquid supply nozzle 40 Head shaft 42 Top ring head 43 Main body vertical movement mechanism 60 Top ring main body 62 Retainer ring 64 Stopper 66 Elastic film 67 Bulkhead 68 Elastic film 69 Elastic membrane 71 Center chamber 72 Ripple chamber 72A Adsorption hole 73 Outer chamber 74 Edge chamber 75 Retainer ring chamber 76 Stopper chamber 81-86 Flow path 90 Pressure adjusting section 91 Control section 95 Pressure sensor

Claims (12)

A top ring main body, a holding mechanism for holding the object to be polished on the lower surface of the top ring main body, and disposed radially outside the object to be polished held by the holding mechanism, independent of the top ring main body Prepare a top ring with a stopper that can move up and down,
While rotating the polishing surface, press the polishing object against the polishing surface by the top ring to polish the surface of the polishing object,
After polishing the surface of the object to be polished, the top ring body is moved upward from the polishing surface while the holding mechanism is operated and the lower surface of the stopper is in contact with the polishing surface for a predetermined time. A polishing method, characterized by comprising: When moving the top ring body upward from the polishing surface,
Determining whether the object to be polished is held on the lower surface of the top ring body;
The polishing method according to claim 1, wherein the polishing surface is stopped when it is determined that the object to be polished is not held on the lower surface of the top ring body. Using a suction mechanism using fluid pressure as the holding mechanism of the top ring,
When determining whether the object to be polished is held on the lower surface of the top ring body,
Measuring the pressure of the fluid used in the suction mechanism;
The polishing method according to claim 2, wherein it is determined whether or not the object to be polished is held on the lower surface of the top ring main body based on the measured pressure of the fluid.   The polishing method according to claim 1, wherein the lower end portion of the inner peripheral surface of the stopper is formed of a material having elasticity.   During polishing of the surface of the object to be polished, the polishing condition of the object to be polished is adjusted by pressing a retainer ring disposed between the object to be polished and the stopper against the polishing surface. The polishing method according to any one of claims 1 to 4.   6. The polishing according to claim 1, wherein the polishing condition of the object to be polished is adjusted by pressing the stopper against the polishing surface during the polishing of the surface of the object to be polished. Method. A polished surface;
A rotating mechanism for rotating the polishing surface;
A top ring that presses the object to be polished against the polishing surface to polish the surface of the object to be polished,
The top ring body,
A holding mechanism for holding the object to be polished on the lower surface of the top ring body;
A stopper that is arranged on the radially outer side of the workpiece held by the holding mechanism and can move up and down independently of the top ring body;
A top ring having
A main body vertical movement mechanism for moving the top ring main body up and down;
A stopper vertical movement mechanism for moving the stopper up and down independently of the top ring body;
A controller that controls at least the operations of the rotation mechanism, the holding mechanism, the main body vertical movement mechanism, and the stopper vertical movement mechanism, and the lower surface of the stopper is moved for a predetermined time with the holding mechanism being operated. A controller that controls the operation of the main body vertical movement mechanism and the stopper vertical movement mechanism so as to move the top ring main body upward from the polishing surface while being in contact with the polishing surface.
A polishing apparatus comprising: A sensor for detecting whether the object to be polished is held on the lower surface of the top ring body;
The said control part stops rotation by the said rotation mechanism, when it is detected by the said sensor that the said to-be-polished object is not hold | maintained on the lower surface of the said top ring main body. Polishing equipment. The holding mechanism is a suction mechanism that sucks the object to be polished to the lower surface of the top ring body using fluid pressure;
The polishing apparatus according to claim 8, wherein the sensor is a pressure sensor that measures a pressure of the fluid used in the suction mechanism.   The polishing apparatus according to any one of claims 7 to 9, wherein a lower end portion of an inner peripheral surface of the stopper is formed of an elastic material. The top ring is disposed radially inside the stopper, and further includes a retainer ring that can move up and down independently of the top ring body and the stopper,
A retainer ring vertical movement mechanism for moving the retainer ring up and down independently of the top ring body and the stopper;
The said control part controls the said retainer ring up-and-down moving mechanism so that the said retainer ring may press the said grinding | polishing surface corresponding to the outer peripheral part of the said to-be-polished object, It is any one of Claim 7 to 10 characterized by the above-mentioned. The polishing apparatus according to item.   The said control part controls the said stopper up-and-down moving mechanism so that the said stopper may press the said grinding | polishing surface corresponding to the outer peripheral part of the said to-be-polished object, It is any one of Claim 7 to 11 characterized by the above-mentioned. The polishing apparatus as described.

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