Retainer ring, substrate polishing device, substrate processing device, and method for cleaning retainer ring

Abstract

This retainer ring is attached to a polishing head for pressing a substrate against a polishing pad. The retainer ring comprises a ring body in which a plurality of groove sections extending from the inner peripheral side toward the outer peripheral side are formed on a bottom surface abutting on the polishing pad. First surfaces constituting the inner walls of the groove sections formed in the ring body and second surfaces facing the first surfaces are formed substantially parallel to each other. The first surfaces and the second surfaces are inclined toward a rotation direction of the retainer ring during polishing of the substrate.

Description

Retainer ring, substrate polishing apparatus, substrate processing apparatus, and method for cleaning retainer ring

[0001] The present invention relates to a retainer ring, a substrate polishing apparatus, a substrate processing apparatus, and a method for cleaning a retainer ring.

[0002] The polishing rate in a substrate polishing apparatus is a factor related to productivity, and a higher polishing rate is generally desirable. The retainer ring used in the substrate polishing apparatus is generally considered to be one factor that determines the polishing rate.

[0003] JP 2015-116656 A JP 2016-155188 A JP 2010-129863 A

[0004] An object of the present invention is to provide a retainer ring, a substrate polishing apparatus, a substrate processing apparatus, and a method for cleaning a retainer ring, which are capable of achieving a good polishing rate.

[0005] [1] A retainer ring according to one aspect of the present invention is a retainer ring attached to a polishing head for pressing a substrate against a polishing pad, and comprises a ring body having a bottom surface that abuts the polishing pad and has a plurality of grooves extending from the inner periphery to the outer periphery, a first surface that forms the inner wall of the groove formed in the ring body and a second surface that faces the first surface are formed approximately parallel, and the first surface and the second surface are inclined toward the direction of rotation of the retainer ring when polishing the substrate.

[0006] [2] A retainer ring according to one aspect of the present invention is the retainer ring described in [1] above, wherein the first surface and the second surface are located in the front and rear, respectively, in the direction of rotation of the retainer ring when polishing the substrate, and the length of the second surface is longer than the length of the first surface in the depth direction of the groove portion.

[0007] [3] A substrate polishing apparatus according to one aspect of the present invention includes the retainer ring according to [1] or [2] above.

[0008] [4] A substrate polishing apparatus according to one aspect of the present invention is the substrate polishing apparatus described in [3] above, further comprising a cleaning mechanism unit having a cleaning nozzle that sprays cleaning liquid toward the groove at an angle that approximately matches the inclination angle of the inner wall of the groove of the retainer ring.

[0009] [5] A substrate polishing apparatus according to one aspect of the present invention is the substrate polishing apparatus described in [3] or [4] above, further comprising a cleaning mechanism for cleaning the retaining ring, wherein when the cleaning mechanism cleans the retaining ring, the retaining ring rotates in a direction opposite to the direction of rotation when polishing the substrate.

[0010] [6] A substrate processing apparatus according to one aspect of the present invention includes the substrate polishing apparatus according to any one of [3] to [5] above.

[0011] [7] A method for cleaning a retainer ring according to one aspect of the present invention is the method for cleaning a retainer ring described in [1] or [2] above, and includes the steps of: placing the retainer ring on top of a cleaning mechanism; rotating the retainer ring in a direction opposite to the direction of rotation when polishing the substrate; and spraying a cleaning liquid from a cleaning nozzle of the cleaning mechanism toward the groove at an angle that approximately matches the inclination angle of the inner wall of the groove in the retainer ring.

[0012] 5 is a diagram showing an example of a schematic configuration of a substrate polishing apparatus according to the present embodiment. FIG. 6 is a perspective view of a substrate polishing apparatus according to the present embodiment. FIG. 7 is a cross-sectional view showing the internal configuration of the substrate polishing apparatus according to the present embodiment. FIG. 8 is a schematic view of a side of a retaining ring according to the present embodiment. FIG. 9 is an enlarged view of region P shown in FIG. 4. FIG. 10 is a diagram explaining the state of a polishing liquid in a groove formed in a retaining ring according to the present embodiment. FIG. 11 is a diagram showing the shape of the bottom surface of a retaining ring according to the present embodiment. FIG. 12 is a diagram showing another example of the shape of the bottom surface of a retaining ring according to the present embodiment. FIG. 13 is a diagram showing a comparison result of the polishing rate of a retaining ring according to the present embodiment with a conventional example. FIG. 14 is a diagram showing an example of a schematic configuration of a cleaning mechanism unit that cleans a retaining ring according to the present embodiment. FIG. 15 is a schematic view of a side of a cleaning mechanism unit according to the present embodiment. FIG. 16 is a diagram showing a flow of a method for cleaning a retaining ring according to the present embodiment. FIG. 17 is a side view of a groove formed in a retaining ring according to Comparative Example 1. FIG. 18 is a side view of a groove formed in a retaining ring according to Comparative Example 2. FIG. 19 is a side view of a groove formed in a retaining ring according to Comparative Example 3. FIG. 20 is a side view of a groove formed in a retaining ring according to Comparative Example 4.

[0013] Hereinafter, each embodiment will be described with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art.

[0014] (Substrate processing apparatus) Fig. 1 is a diagram showing an example of the schematic configuration of a substrate processing apparatus 100 according to this embodiment. As shown in Fig. 1, the substrate processing apparatus 100 has a substantially rectangular housing 2, the interior of which is partitioned by partitions 2a and 2b into a load / unload section 6, a polishing section (substrate polishing apparatus) 1, and a cleaning section 8. This substrate processing apparatus 100 has an operation control section (control device) 10 that controls wafer processing operations.

[0015] The load / unload section 6 is equipped with load ports 12 on which wafer cassettes containing a large number of wafers are placed. A traveling mechanism 14 is installed in the load / unload section 6 along the row of load ports 12, and a transfer robot (loader) 16 that can move along the direction in which the wafer cassettes are arranged is installed on the traveling mechanism 14. The transfer robot 16 can access the wafer cassettes placed on the load ports 12 by moving on the traveling mechanism 14.

[0016] The polishing section (substrate polishing apparatus) 1 is an area where wafers are polished and includes a first polishing unit 1A, a second polishing unit 1B, a third polishing unit 1C, and a fourth polishing unit 1D. The first polishing unit 1A includes a first polishing table 22A to which a polishing pad 20 having a polishing surface is attached, a first polishing head 24A for holding a wafer and polishing the wafer while pressing it against the polishing pad 20 on the first polishing table 22A, a first polishing liquid supply nozzle 26A for supplying a polishing liquid (e.g., slurry) or a dressing liquid (e.g., pure water) to the polishing pad 20, a first dressing unit 28A for dressing the polishing surface of the polishing pad 20, and a first atomizer 30A for spraying a mixture of a liquid (e.g., pure water) and a gas (e.g., nitrogen gas) or a liquid (e.g., pure water) onto the polishing surface.

[0017] Similarly, the second polishing unit 1B comprises a second polishing table 22B having a polishing pad 20 attached thereto, a second polishing head 24B, a second polishing liquid supply nozzle 26B, a second dressing unit 28B, and a second atomizer 30B; the third polishing unit 1C comprises a third polishing table 22C having a polishing pad 20 attached thereto, a third polishing head 24C, a third polishing liquid supply nozzle 26C, a third dressing unit 28C, and a third atomizer 30C; and the fourth polishing unit 1D comprises a fourth polishing table 22D having a polishing pad 20 attached thereto, a fourth polishing head 24D, a fourth polishing liquid supply nozzle 26D, a fourth dressing unit 28D, and a fourth atomizer 30D.

[0018] A first linear transporter 40 is disposed adjacent to the first polishing unit 1A and the second polishing unit 1B. This first linear transporter 40 is a mechanism for transporting wafers between four transfer positions (first transfer position TP1, second transfer position TP2, third transfer position TP3, and fourth transfer position TP4). A second linear transporter 42 is disposed adjacent to the third polishing unit 1C and the fourth polishing unit 1D. This second linear transporter 42 is a mechanism for transporting wafers between three transfer positions (fifth transfer position TP5, sixth transfer position TP6, and seventh transfer position TP7).

[0019] A lifter 44 for receiving a wafer from the transfer robot 16 is disposed adjacent to the first transfer position TP1. The wafer is delivered from the transfer robot 16 to the first linear transporter 40 via this lifter 44. A shutter (not shown) is provided on the partition wall 2a between the lifter 44 and the transfer robot 16, and the shutter is opened during wafer delivery so that the wafer can be delivered from the transfer robot 16 to the lifter 44.

[0020] The wafer is transferred to the lifter 44 by the transfer robot 16, and then transferred from the lifter 44 to the first linear transporter 40, and then transported to the polishing units 1A and 1B by the first linear transporter 40. The polishing head 24A of the first polishing unit 1A moves between a position above the first polishing table 22A and the second transfer position TP2 by the swing movement of the head arm 31. Therefore, the wafer is transferred to and from the polishing head 24A at the second transfer position TP2.

[0021] Similarly, the polishing head 24B of the second polishing unit 1B moves between a position above the polishing table 22B and a third transfer position TP3, and wafers are transferred to and from the polishing head 24B at the third transfer position TP3. The polishing head 24C of the third polishing unit 1C moves between a position above the polishing table 22C and a sixth transfer position TP6, and wafers are transferred to and from the polishing head 24C at the sixth transfer position TP6. The polishing head 24D of the fourth polishing unit 1D moves between a position above the polishing table 22D and a seventh transfer position TP7, and wafers are transferred to and from the polishing head 24D at the seventh transfer position TP7.

[0022] A swing transporter 46 is disposed between the first linear transporter 40, the second linear transporter 42, and the cleaning unit 8. Wafers are transferred from the first linear transporter 40 to the second linear transporter 42 by the swing transporter 46. The wafers are transported by the second linear transporter 42 to the third polishing unit 1C and / or the fourth polishing unit 1D.

[0023] A wafer temporary placement table 48 mounted on a frame (not shown) is disposed to the side of the swing transporter 46. As shown in FIG. 3 , this temporary placement table 48 is disposed adjacent to the first linear transporter 40 and is located between the first linear transporter 40 and the cleaning unit 8. The swing transporter 46 transports wafers between the fourth transfer position TP4, the fifth transfer position TP5, and the temporary placement table 48.

[0024] The wafer placed on the temporary table 48 is transported to the cleaning unit 8 by a first transfer robot 50 of the cleaning unit 8. The cleaning unit 8 includes a primary cleaning unit 52 and a secondary cleaning unit 54 that clean the polished wafer with a cleaning liquid, and a drying unit 56 that dries the cleaned wafer. The first transfer robot 50 operates to transport the wafer from the temporary table 48 to the primary cleaning unit 52 and then from the primary cleaning unit 52 to the secondary cleaning unit 54. A second transfer robot 58 is disposed between the secondary cleaning unit 54 and the drying unit 56. The second transfer robot 58 operates to transport the wafer from the secondary cleaning unit 54 to the drying unit 56.

[0025] The dried wafer is removed from the drying unit 56 by the transfer robot 16 and returned to the wafer cassette. In this manner, in the substrate processing apparatus 100, the wafer undergoes a series of processes including polishing, cleaning, and drying.

[0026] (Substrate Polishing Apparatus) Next, a substrate polishing apparatus 1 according to this embodiment will be described. The first polishing unit 1A, the second polishing unit 1B, the third polishing unit 1C, and the fourth polishing unit 1D of the substrate polishing apparatus 1 have the same configuration. Therefore, the first polishing unit 1A will be described below.

[0027] Fig. 2 is a perspective view showing the first polishing unit 1A. As shown in Fig. 2, the first polishing unit 1A includes a polishing table 22A that supports the polishing pad 20, a polishing head 24A that presses the wafer W against the polishing pad 20, and a polishing liquid supply nozzle 26A that supplies a polishing liquid (slurry) to the polishing pad 20. In Fig. 2, the first dressing unit 28A and the first atomizer 30A are not shown.

[0028] The polishing table 22A is connected via a table shaft 23 to a table motor 25 disposed below the table shaft 23, and the table motor 25 rotates the polishing table 22A in the direction indicated by the arrow. A polishing pad 20 is affixed to the upper surface of the polishing table 22A, and the upper surface of the polishing pad 20 forms a polishing surface 20a for polishing the wafer W. The polishing head 24A is fixed to the lower end of a shaft 27. The polishing head 24A is configured to hold the wafer W on its lower surface by vacuum suction. The shaft 27 is connected to a rotation mechanism (described later) installed in a head arm 31, and the polishing head 24A is rotated via the shaft 27 by this rotation mechanism.

[0029] The surface of the wafer W is polished as follows: The polishing head 24A and the polishing table 22A are rotated in the directions indicated by the arrows, and a polishing liquid (slurry) is supplied onto the polishing pad 20 from the polishing liquid supply nozzle 26A. In this state, the wafer W is pressed against the polishing surface 20a of the polishing pad 20 by the polishing head 24A. The surface of the wafer W is polished by the mechanical action of abrasive grains contained in the polishing liquid and the chemical action of chemical components contained in the polishing liquid.

[0030] The wafer W polished by the first polishing unit 1A shown in Figure 2 is moved to the second transfer position TP2 (see Figure 1) by the swinging motion of the head arm 31. The second transfer position TP2 functions as a wafer transfer position, where the wafer W is released. A pusher is provided at the second transfer position (wafer transfer position) TP2, and the polished wafer W is transferred to the transfer stage of the first linear transporter 40 by the up and down movement of the pusher.

[0031] 3 is a cross-sectional view of the first polishing unit 1A (substrate polishing apparatus 1). As shown in FIG. 3, the polishing head 24A includes a polishing head main body 18 that presses the wafer W against the polishing surface 20a, and a retainer ring 19 that supports the outer periphery of the wafer W to prevent the wafer W from jumping out of the polishing head 24A. The shape of the retainer ring 19 will be described later.

[0032] The polishing head 24A is connected to a shaft 27, and a rotary joint 35 is attached to the upper end of the shaft 27. The shaft 27 is configured to move up and down relative to the head arm 31 by a vertical movement mechanism 37, so that the entire polishing head 24A can be raised and lowered relative to the head arm 31 to position it.

[0033] The up-and-down movement mechanism 37 that moves the shaft 27 and polishing head 24A up and down includes a bridge 38 that rotatably supports the shaft 27 via a bearing 36, a ball screw 71 attached to the bridge 38, a support base 39 supported by a support column 70, and a servo motor 78 provided on the support base 39. The support base 39 that supports the servo motor 78 is fixed to the head arm 31 via the support column 70.

[0034] The ball screw 71 includes a screw shaft 71a connected to a servo motor 78 and a nut 71b onto which the screw shaft 71a is threaded. The shaft 27 moves up and down integrally with the bridge 38. Therefore, when the servo motor 78 is driven, the bridge 38 moves up and down via the ball screw 71, which in turn moves the shaft 27 and the polishing head 24A up and down.

[0035] Next, the rotation mechanism of the shaft 27 will be described. The shaft 27 is connected to a rotary cylinder 72 via a key (not shown). The rotary cylinder 72 is provided with a timing pulley 73 on its outer periphery. A head motor 76 is fixed to the head arm 31, and the timing pulley 73 is connected to a timing pulley 75 attached to the head motor 76 via a timing belt 74. By rotating the head motor 76, the rotary cylinder 72 and the shaft 27 rotate together via the timing pulley 75, timing belt 74, and timing pulley 73, thereby rotating the polishing head 24A. The head arm 31 is supported by an arm shaft 77 rotatably supported on a frame (not shown). The head motor 76, servo motor 78, and other internal devices are controlled by an operation control unit (control device) 10 (see FIG. 1) of the substrate processing apparatus 100.

[0036] (Retainer Ring) Next, the retainer ring 19 according to this embodiment will be described.

[0037] Fig. 4 is a schematic side view of the retainer ring 19 according to this embodiment. As shown in Fig. 4, the retainer ring 19 has a ring main body 19A, and a plurality of grooves 19b are formed in the bottom surface 19a of the ring main body 19A (the surface that comes into contact with the polishing surface 20a of the polishing pad 20). The plurality of grooves 19b are formed so that their inner walls are inclined relative to the polishing surface 20a of the polishing pad 20 in the direction A of rotation of the retainer ring 19 during polishing of the substrate (wafer W).

[0038] Fig. 5 is an enlarged view of region P shown in Fig. 4. As shown in Fig. 5, the inner wall of groove 19b has a first surface and an opposing second surface. First surface 19b1 and second surface 19b2 are located in front and behind, respectively, in the rotation direction A of retainer ring 19 during polishing of the substrate (wafer W).

[0039] The first surface 19b1 and the second surface 19b2 are formed substantially parallel to each other. Therefore, even if the bottom surface 19a of the retainer ring 19 (ring body 19A) wears (decreases in the thickness direction) due to sliding contact with the polishing pad 20, the width D (see FIG. 5) of the opening of the groove 19b does not change. In other words, even if the bottom surface 19a of the retainer ring 19 wears, the contact area of ​​the retainer ring 19 with the polishing pad 20 does not change. Therefore, the pressure pressing on the polishing pad 20 can be kept constant.

[0040] Furthermore, first surface 19b1 and second surface 19b2 are formed so as to be inclined toward the rotation direction A of retainer ring 19 during polishing of the substrate (wafer W). Specifically, the inclination angle θ1 of first surface 19b1 and second surface 19b2 is 90 degrees or more, and more preferably an obtuse angle of 100 to 135 degrees.

[0041] 6 is a diagram showing the state of the polishing liquid (slurry) S drawn into the groove 19b during polishing of a substrate (wafer W). When polishing a substrate (wafer W), the polishing liquid S supplied to the polishing pad 20 is drawn into the groove 19b. The polishing liquid S drawn into the groove 19b then rises upward (in the Y direction in FIG. 6 ) as the retainer ring 19 rotates. In contrast, in the retainer ring 19 of this embodiment, the inner wall (second surface 19b2) of the groove 19b is inclined toward the rotation direction A of the retainer ring 19 during polishing of the substrate (wafer W). This presses the polishing liquid S downward and forward in the rotation direction A (in the X direction in FIG. 6 ), preventing the polishing liquid S from escaping upward within the groove 19b. Therefore, when polishing a substrate (wafer W), a flow of polishing liquid S is generated from inside groove 19b of retainer ring 19 toward polishing surface 20a of polishing pad 20, and polishing liquid S can be spread over a wider area on polishing surface 20a, thereby increasing the proportion of polishing liquid that contributes to polishing.

[0042] Furthermore, since the inner wall (second surface 19b2) of groove portion 19b is inclined toward the rotation direction A of retainer ring 19 when polishing the substrate (wafer W), the area of ​​second surface 19b2 of the inner wall of groove portion 19b is larger than when it is not inclined, and therefore more polishing liquid S can be taken into groove portion 19b.

[0043] 7 is a diagram showing the shape of the groove 19b as viewed from the bottom surface 19a of the retainer ring 19 (ring body 19A) (only a portion of the arc on the circumference is shown). As shown in FIG. 7, the groove 19b of the retainer ring 19 extends from the inner periphery to the outer periphery, and the shape of the groove 19b as viewed from the bottom surface 19a is radial. By shaping the groove 19b in this way, the polishing liquid S can be taken into the inside of the groove 19b.

[0044] 8 is a diagram showing another example of the shape of the groove 19b as viewed from the bottom surface 19a of the retainer ring 19 (ring main body 19A). As shown in Fig. 8, the groove 19b may be formed so that it is inclined when viewed from the bottom surface 19a of the retainer ring 19. By shaping the groove 19b in this way, the area of ​​the inner wall (second surface 19b2) can be increased, allowing more polishing liquid S to be taken into the groove 19b.

[0045] Comparative Example 1: FIG. 13 is an enlarged view of the groove 191b of the retainer ring 191 (ring body 191A) according to Comparative Example 1. As shown in FIG. 13, the retainer ring 191 according to Comparative Example 1 is formed so that the width of the groove 191b decreases from the bottom surface 191a upward (in the depth direction). Therefore, when the bottom surface 191a of the retainer ring 191 wears (decreases in the thickness direction) due to sliding contact with the polishing pad 20, the width D1 of the opening of the groove 191b changes (becomes smaller). In other words, when the bottom surface 191a of the retainer ring 191 wears, the contact area of ​​the retainer ring 191 with the polishing pad 20 changes. Therefore, the pressure pressing the polishing pad 20 cannot be kept constant.

[0046] 14 is an enlarged view of the groove 192b of the retainer ring 192 (ring body 192A) according to Comparative Example 2. As shown in FIG. 14 , the retainer ring 192 according to Comparative Example 2 is formed so that the width of the groove 192b decreases upward (in the depth direction) from the bottom surface 192a. Therefore, when the bottom surface 192a of the retainer ring 192 wears (decreases in the thickness direction) due to sliding contact with the polishing pad 20, the width D2 of the opening of the groove 192b changes (becomes smaller). In other words, when the bottom surface 192a of the retainer ring 192 wears, the contact area of ​​the retainer ring 192 with the polishing pad 20 changes. Therefore, the pressure pressing the polishing pad 20 cannot be kept constant.

[0047] 15 is an enlarged view of the groove 193b of the retainer ring 193 (ring body 193A) according to Comparative Example 3. As shown in FIG. 15 , the retainer ring 193 according to Comparative Example 3 is formed so that the width of the groove 193b increases upward (in the depth direction) from the bottom surface 193a. Therefore, when the bottom surface 193a of the retainer ring 193 wears (decreases in the thickness direction) due to sliding contact with the polishing pad 20, the width D3 of the opening of the groove 193b changes (increases). In other words, when the bottom surface 193a of the retainer ring 193 wears, the contact area of ​​the retainer ring 193 with the polishing pad 20 changes. Therefore, the pressure pressing the polishing pad 20 cannot be kept constant.

[0048] 16 is an enlarged view of the groove 194b of the retainer ring 194 (ring body 194A) according to Comparative Example 4. In the retainer ring 194 of this comparative example, the inner walls of the groove 194b are generally parallel to each other. Therefore, even if the bottom surface 194a of the retainer ring 194 wears (decreases in the thickness direction) due to sliding contact with the polishing pad 20, the width D4 of the opening of the groove 194b does not change, and the contact area of ​​the retainer ring 194 with the polishing pad 20 does not change. However, because the inner walls of the groove 194b are vertical (90 degrees), the polishing liquid S taken into the groove 194b during polishing of the substrate (wafer W) floats upward (in the Y1 direction in FIG. 16 ) within the groove 194b. Therefore, it is not possible to create a flow of the polishing liquid S from inside the groove portion 194b of the retainer ring 194 toward the polishing surface 20a of the polishing pad 20, and the polishing liquid S cannot be spread over a wider area on the polishing surface 20a.

[0049] (Comparison of Polishing Rate with Comparative Examples) FIG. 9 shows the results of comparing the polishing rates when the retainer ring 19 according to the present embodiment is used and when the retainer ring 194 of Comparative Example 4 (see FIG. 16) is used. As shown in FIG. 9, when the retainer ring 19 according to the present embodiment is used, the polishing rate is improved by about 10% compared to Comparative Example 4. Therefore, by using the retainer ring 19 according to the present embodiment, it is possible to significantly improve the polishing rate. When the polishing pad during polishing is observed when the retainer ring 19 according to the present embodiment is used and when the retainer ring 194 of Comparative Example 4 (see FIG. 16) is used, it can be confirmed that the polishing liquid S is spread over a wider area on the polishing pad when the retainer ring 19 according to the present embodiment is used. From this, it can be inferred that the amount of polishing liquid S contributing to polishing is increasing.

[0050] As such, the retainer ring 19 of this embodiment is used in a polishing head 24 for pressing a substrate against a polishing pad, and is a retainer ring 19 for supporting the outer periphery of a substrate W held by the polishing head 24, and is provided with a ring body 19A having a bottom surface 19a that abuts the polishing pad 20 and has multiple grooves extending from the inner periphery to the outer periphery, and a first surface 19b1 that forms the inner wall of the grooves 19b formed in the ring body 19A and a second surface 19b2 that faces the first surface 19b1 are formed approximately parallel, and the first surface 19b1 and the second surface 19b2 are inclined toward the rotation direction A of the retainer ring when the substrate W is polished.

[0051] With this configuration, the retainer ring 19 of this embodiment can achieve a good polishing rate.

[0052] (Cleaning Mechanism) Next, a cleaning mechanism for cleaning the groove of the retainer ring according to this embodiment will be described. The cleaning mechanism also cleans the gap between the retainer ring 19 and the membrane, but a description thereof will be omitted.

[0053] As an example, the following description will be given based on the positional relationship between the first polishing unit 1A and the second transfer position (wafer transfer position) TP2, but the positional relationship between the second polishing unit 1B and the third transfer position TP3, the relationship between the third polishing unit 1C and the sixth transfer position TP6, and the positional relationship between the fourth polishing unit 1D and the seventh transfer position TP7 are similar.

[0054] As shown in Fig. 10, the polishing head 24A is moved between a position above the first polishing table 22A and a second transfer position (wafer transfer position) TP2 by the swinging motion of the head arm 31. A pusher (not shown) is disposed at the second transfer position (wafer transfer position) TP2. Fig. 10 also shows the traveling rails 47 of the first linear transporter 40, along which the transfer stage 49 moves. A wafer W is shown placed on the transfer stage 49.

[0055] A cleaning mechanism 60 for cleaning the retainer ring 19 of the polishing head 24A is disposed at the second transfer position (wafer transfer position) TP2, and the cleaning mechanism 60 includes a plurality of comb-shaped cleaning units 61 (in the illustrated example, three cleaning units 61). Each cleaning unit 61 is capable of reciprocating between a radially outer position (retracted position) and a radially inner position (cleaning position) as indicated by the arrows.

[0056] 11 is a diagram showing how the cleaning mechanism 60 according to this embodiment cleans the inside of the groove of the retainer ring 19 (ring main body 19A) when moved to the cleaning position. In FIG. 11, the polishing head 24A holding the wafer W is located at the second transfer position (wafer transfer position) TP2. For ease of explanation, only the retainer ring 19 (ring main body 19A) is shown for the polishing head 24A, and only the cleaning nozzle 61n provided on the cleaning unit 61 is shown for the cleaning mechanism.

[0057] As shown in Figure 11, the cleaning mechanism 60 rotates the polishing head 24A in a direction (rotation direction B) opposite to the rotation direction A used when polishing the wafer W, and sprays cleaning liquid from the cleaning nozzle 61n toward the groove portion 19b of the retainer ring 19 (ring main body 19A).

[0058] Here, the reason why the rotation direction of the polishing head 24A during cleaning is reversed from that during polishing will be explained. If the rotation direction of the polishing head 24A during cleaning were the same as that during polishing (rotation direction A in FIG. 4 ), the cleaning liquid would be knocked downward by the inner wall (second surface 19b2) of the groove 19b, making it difficult to clean the depths of the groove 19b. On the other hand, by rotating the polishing head 24A during cleaning in the opposite direction from that during polishing (rotation direction B), the cleaning liquid is not knocked downward by the inner wall (second surface 19b2) of the groove 19b. Rather, the inner wall (second surface 19b2) of the groove 19b scoops up the cleaning liquid, allowing more cleaning liquid to enter the groove 19b, thereby improving the cleaning effect. For this reason, in this embodiment, the rotation direction of the polishing head 24A during cleaning of the retainer ring 19 by the cleaning mechanism unit 60 is reversed from that during polishing.

[0059] Furthermore, the spray angle θ2 of the cleaning liquid sprayed from the cleaning nozzle 61n (the angle with respect to a plane parallel to the bottom surface 19a of the retaining ring 19) may be set to approximately match the inclination angle θ1 of the inner wall of the groove of the retaining ring 19. This allows more cleaning liquid to enter the inside of the groove of the retaining ring 19, thereby improving the cleaning effect.

[0060] (Method of Cleaning the Retainer Ring) Next, a method of cleaning the retainer ring 19 using the cleaning mechanism section 60 will be described.

[0061] FIG. 12 is a flowchart showing the procedure of the method for cleaning the retainer ring 19 by the cleaning mechanism section 60.

[0062] 12, first, the retaining ring 19 is placed above the cleaning mechanism 60 (step S1). Specifically, the polishing head 24 having the retaining ring 19 is placed above the cleaning mechanism 60 by swinging the head arm 31 (see FIG. 10). For example, when cleaning the retaining ring 19 of the polishing head 24A, the polishing head 24A is moved from a position above the first polishing table 22A to the second transfer position (wafer transfer position) TP2 by swinging the head arm 31, thereby placing the polishing head 24A above the cleaning mechanism 60.

[0063] Next, the retainer ring is rotated in the direction opposite to the direction of rotation during polishing of the substrate (rotation direction B shown in FIG. 11) (step S2). Specifically, the head motor 76 (see FIG. 3) is rotated in the direction opposite to the direction of rotation during polishing, thereby rotating the polishing head 24A.

[0064] Then, the cleaning liquid is sprayed from the cleaning nozzle 61n of the cleaning mechanism 60 toward the groove at an angle that substantially matches the inclination angle of the inner wall of the groove of the retainer ring 19 (ring body 19A) (step S3).

[0065] As described above, the method for cleaning the retainer ring 19 according to this embodiment includes step S1 of placing the retainer ring 19 on top of the cleaning mechanism unit 60, step S2 of rotating the retainer ring 19 in a direction opposite to the rotation direction during polishing of the substrate (wafer W), and step S3 of spraying a cleaning liquid from the cleaning nozzle of the cleaning mechanism unit 60 toward the groove at an angle θ2 that is approximately equal to the inclination angle θ1 of the inner wall of the groove of the retainer ring 19.

[0066] This configuration makes it possible to efficiently clean the inside of the groove formed on the bottom surface 19a of the retainer ring 19.

[0067] The above-described embodiments have been described for the purpose of enabling a person having ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would naturally be possible for a person skilled in the art, and the technical concept of the present invention may also be applied to other embodiments. The present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims.

Claims

1. A retainer ring attached to a polishing head for pressing a substrate against a polishing pad, comprising a ring body with a plurality of grooves extending from the inner periphery to the outer periphery formed on its bottom surface that abuts the polishing pad, a first surface that forms the inner wall of the groove formed on the ring body and a second surface that faces the first surface are formed approximately parallel, and the first surface and the second surface are inclined toward the direction of rotation of the retainer ring when polishing the substrate.

2. The retainer ring according to claim 1, wherein the first surface and the second surface are located in the front and rear, respectively, in the direction of rotation of the retainer ring when polishing the substrate, and the length of the second surface is longer than the length of the first surface in the depth direction of the groove.

3. A substrate polishing apparatus comprising the retainer ring according to claim 1 or 2.

4. The substrate polishing apparatus according to claim 3, further comprising a cleaning mechanism having a cleaning nozzle that sprays a cleaning liquid toward the groove at an angle that substantially matches the inclination angle of the inner wall of the groove of the retainer ring.

5. The substrate polishing apparatus according to claim 3, further comprising a cleaning mechanism for cleaning the retaining ring, wherein when the cleaning mechanism cleans the retaining ring, the retaining ring rotates in a direction opposite to the direction of rotation when polishing the substrate.

6. A substrate processing apparatus comprising the substrate polishing apparatus according to claim 3.

7. A method for cleaning a retainer ring as described in claim 1, comprising the steps of: placing the retainer ring on top of a cleaning mechanism; rotating the retainer ring in a direction opposite to the direction of rotation when polishing the substrate; and spraying a cleaning liquid from a cleaning nozzle of the cleaning mechanism toward the groove at an angle that approximately matches the inclination angle of the inner wall of the groove in the retainer ring.

Images