Polishing head, polishing device and method for removing a workpiece

Abstract

The present invention relates to a polishing head 11 with at least one disc-shaped carrier 13 for holding the back side of a workpiece W, in which a carrier contact area 13b is formed on a circumferential section, a head body 12 for holding the carrier, and an outwardly projecting, annular head body contact area 12a, as well as a membrane 14 for connecting the head body to the carrier. The workpiece is detached from a polishing pad 22 by lifting the head body and the carrier contact area, wherein the carrier contact area and the head body contact area interlock when the workpiece is detached from the polishing pad by lifting the polishing head after polishing the workpiece. A spacer 15 is provided between the carrier contact area and the head body contact area in a portion of the carrier contact area and / or the head body contact area.The spacer rests against the support area and the head body contact area when the polishing head is lifted, so that the workpiece is released from the polishing pad by lifting the support at an angle. The thickness of the spacer is adjustable to set the tilt angle when the polishing head is lifted.

Description

TECHNICAL AREA

[0001] The present invention relates to a polishing head for holding a back side of a workpiece when a front side of the workpiece is being polished, a polishing device comprising this polishing head, and a method for removing the workpiece from a polishing pad. STATE OF THE ART

[0002] Devices for polishing the surface of a semiconductor wafer, such as a silicon wafer, include a single-sided polishing device, in which the workpiece is polished on one side at a time, and a double-sided polishing device, in which both sides of the workpiece are polished at the same time.

[0003] For example, in the Fig. As shown in Figure 10, a typical single-sided polishing device comprises a rotary table 73 to which a polishing pad 74 is attached, a polishing agent feed device 76, a polishing head 72, and the like. The polishing device 71 polishes a wafer W by holding the wafer W with the polishing head 72, supplying the polishing agent 75 to the polishing pad 74 via the polishing agent feed device 76, rotating the rotary table 73 or the polishing head 72, and bringing the surface of the wafer W into sliding contact with the polishing pad 74.

[0004] Methods for holding the workpiece include a method for attaching the workpiece to a flat, disc-like plate with an adhesive such as wax, a method for adhesively attaching the workpiece to a soft cushion (an additional cushion) using water, a method for suctioning the workpiece using a vacuum, and the like.

[0005] In the Fig. Figure 11 shows a schematic example of a polishing head that holds the workpiece with the auxiliary pad. This polishing head 91 has the auxiliary pad 95, which is made of polyurethane and the like, and is attached to the underside of a disc-like carrier 92, which is made of ceramic or the like.

[0006] The cushion 95 is allowed to absorb water in order to hold the workpiece W in place via surface tension. To prevent the workpiece W from detaching from the carrier 92 during the polishing process, a ring-shaped molded part 94 is also provided around the carrier 92.

[0007] When polishing a large-diameter workpiece, such as a silicon single-crystal wafer with a diameter of 300 mm, a problem arises when using a flat polishing pad without a groove. This is because, when lifting the polishing head to remove the workpiece from the pad after polishing, the polished workpiece adheres to a surface of the pad due to the surface tension of the polishing compound, thus remaining stuck to the pad. Furthermore, if the suction force of the polishing head becomes too strong, the bearing components supporting the rotary table are subjected to a load that causes the rotary table to lift.

[0008] In light of these problems, a method was adopted, for example, in which the suction power of the polishing pad is reduced by forming a groove on the polishing pad, or in which the polishing head is lifted after it has once left the rotating plate laterally (hereinafter referred to as the shearing method. See, for example, the Japanese patent application with publication number (kokai) 2001-341070, published under file number JP 2001-341070A).

[0009] However, quality problems arise during the formation of the groove on the polishing pad. These problems include the formation of a fine waviness on the workpiece surface, which is due to imperfections in the polishing pad's groove. Additionally, the edge of the workpiece can become caught in the groove and thus damaged, or a depression can form on the outer circumference. Furthermore, the shearing process presents problems because the device becomes quite large to allow space for swiveling out the polishing head and other components.

[0010] US Patent 5,527,209 A discloses a device that reduces the forces required to remove a wafer from a wet polishing surface after polishing. The device includes a mounting that can be attached to a polishing device to allow a mounting surface, configured to engage two areas of the wafer, to be inclined relative to the polishing surface. Means are provided for defining an adhesive force between the mounting surface and one of the two wafer areas, as well as means for defining an adhesive force between the mounting surface and the other of the two wafer areas, which differs from the adhesive force defined between the mounting surface and one wafer area, in order to create a non-parallel relationship between one wafer area and the polishing surface. The device may further include lifting prongs arranged at different distances from the polishing surface.When the polishing head is lifted from a polishing pad, one of the lifting prongs engages a lifting support before the other lifting prongs. This arrangement of lifting prongs and lifting supports allows the area of ​​the wafer adjacent to the stronger vacuum adhesion force to be lifted first, so that the wafer tilts as it is pulled away from the polishing pad.

[0011] The translation DE 698 07 780 T2 of European patent EP 0879678 B1 discloses a carrier head for a chemical-mechanical polishing system. The carrier head includes a substrate detection device. The carrier head comprises a base and a flexible element connected to the base to define a chamber. An underside of the flexible element forms a substrate receiving surface. The substrate detection device includes a sensor for measuring pressure in the chamber and generating a representative output signal, as well as a processor configured to indicate, in response to the output signal, whether the substrate is attached to the substrate receiving surface. REVELATION OF THE INVENTION

[0012] In view of the problems described above, the object of the present invention is to provide a polishing head in which the workpiece can be easily, safely and reliably detached from the polishing pad by lifting the polishing head holding the workpiece, without moving the polishing head out of the rotary plate or forming a groove on the polishing pad, wherein the release conditions of the workpiece, in particular an angle of inclination, can be easily adjusted.

[0013] To solve the aforementioned problem, the present invention provides a polishing head with at least one disc-shaped carrier for holding a rear side of a workpiece, in which an annular projecting section, which protrudes upwards, and an annular carrier contact area, which projects inwards from the projecting section, are formed on a circumferential section, a head body for holding the carrier, in which a space section is formed inside, and an outwardly projecting, annular head body contact area, which is formed on the outside, wherein the head body is rotatable, and a membrane for connecting the head body to the carrier and for tightly sealing the space section of the head body;wherein the polishing head holds the back of the workpiece in which a pressure of the tightly sealed chamber section is set by means of a pressure adjusting device connected to the chamber section, when a front of the workpiece is polished by bringing it into sliding contact with a polishing pad attached to a rotary table, and the workpiece is detached from the polishing pad by lifting the head body and the support contact area, wherein the support contact area and the head body contact area interlock when the workpiece is detached from the polishing pad by lifting the polishing head after polishing the workpiece;wherein a spacer is provided at least between the support area and the head body support area, in a part of the support area and / or the head body support area, and the spacer is supported on the support area and / or the head body support area when the head body is lifted, so that the workpiece is released from the polishing pad by lifting the support at an angle when the workpiece is released from the polishing pad by lifting the polishing head, wherein a thickness of the spacer is adjustable in order to set an angle of inclination when lifting the polishing head.

[0014] If the workpiece has been polished with the polishing head described above and is removed from the polishing pad after polishing, the workpiece can be easily, safely, and reliably detached from the polishing pad. Furthermore, since the tilt angle when lifting the polishing head can be adjusted by changing the thickness of the spacer, the tilt angle of the polishing head can be set with a simple process. In contrast to the method of forming a groove on the polishing pad, the quality of the polished surface of the workpiece is not impaired, and unlike the shearing method, it is also not necessary for a polishing device to be large.

[0015] It is preferred that the polishing head has an additional pad on a surface of the carrier, with the surface holding the back of the workpiece.

[0016] If the polishing head has an additional pad on the backing surface, with this surface holding the back of the workpiece, the backing can securely hold the workpiece. Using the polishing head described above thus allows for more reliable release of the workpiece from the polishing pad.

[0017] Furthermore, the carrier can be capable of holding a semiconductor wafer with a diameter of 300 mm or more as a workpiece.

[0018] Even if the carrier holds a semiconductor wafer with a diameter of 300 mm or more as the workpiece, and the semiconductor wafer adheres to the polishing pad with a strong force after polishing, the workpiece can be easily, safely and reliably removed from the polishing pad when using the polishing head according to the present invention.

[0019] The object of the invention is further achieved by a polishing device used for polishing the surface of a workpiece, comprising at least the following: a polishing pad attached to a rotary plate; a polishing agent supply device for supplying a polishing agent to the polishing pad; and a polishing head for holding the workpiece, which is the polishing head according to the present invention.

[0020] When the workpiece is polished and, after the polishing process, is removed from the polishing pad by the polishing device comprising the polishing head according to the present invention, the polishing device can easily, safely, and reliably remove the workpiece from the polishing pad. Furthermore, in contrast to the method of forming the groove on the polishing pad, the quality of the polished surface of the workpiece is not impaired, and unlike the shearing method, it is also not necessary for a polishing device to have large dimensions.

[0021] It is preferred that the polishing device has a device for automatically setting a rotation stop position of the polishing head.

[0022] Thus, if the polishing device has the device for automatically adjusting the rotation stop position of the polishing head, the polishing device can adjust the rotation angle position of the polishing head to the position in which the wafer is more easily released and stop the polishing head in a corresponding position.

[0023] The object of the invention is further achieved by a method for detaching a workpiece from a polishing pad after dressing the polishing pad attached to a rotary table and for bringing a surface of the workpiece into sliding contact with the dressed polishing pad for polishing, which comprises the following steps: holding and polishing the workpiece with the polishing head according to the present invention; stopping the rotation of the polishing head such that a rotational position of the spacer is within 30° of a center point of the polishing head with respect to a center point of the polishing pad; and detaching the workpiece by lifting the head body in the rotational position.

[0024] The process of dressing or smoothing the polishing pad, polishing the front of the workpiece with the polishing head according to the present invention, stopping the rotation of the polishing head such that, after polishing the workpiece, the rotational position of the spacer is within 30° of the center of the polishing head, and removing the workpiece from the polishing head, thus enables easier, safer, and more reliable removal of the workpiece from the polishing head. Furthermore, in contrast to the method of forming the groove on the polishing pad, the quality of the polished surface of the workpiece is not impaired, and unlike the shearing method, it is also not necessary for a polishing device to be large.

[0025] The use of the polishing head according to the present invention enables easy, safe, and reliable removal of the workpiece from the polishing pad, without any deterioration in the quality of the polished surface of the workpiece during removal. Since the tilt angle when lifting the polishing head can be adjusted by changing the thickness of the spacer, the tilt angle of the polishing head can also be easily adjusted, and the wafer removal conditions can be readily adapted.

[0026] In addition, by polishing the workpiece with the polishing head according to the present invention after dressing, stopping the rotation of the polishing head in such a way that the spacer corresponds to the near area of ​​a center point of the rotary table, and detaching the workpiece from the polishing pad, it is possible to detach the workpiece from the polishing pad more easily, safely and reliably. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic sectional view showing a first embodiment of the polishing head according to the present invention; Fig. 2 is a schematic top view showing an example of the polishing head according to the present invention; Fig. 3 is a schematic basic view showing an example of the polishing device comprising the polishing head according to the present invention; Fig. Figure 4 is a schematic sectional view showing a movement at the time of detachment of the workpiece from the polishing pad using the polishing head according to the present invention; Fig. Figure 5 is a schematic sectional view showing a movement at the time of detachment of the workpiece from the polishing pad using the polishing head according to the present invention; Fig. Figure 6 is an explanatory view showing the case where one looks from above at the rotation stop position of the polishing head; Fig. 7 (a) is a schematic top view showing one type of training, and Fig. 7 (b) is a diagram showing a height distribution in the diameter direction of the polishing pad after dressing; Fig. Figure 8 is a schematic sectional view showing an example of the polishing head, which has the spacer on the head body; Fig. Figure 9 is a schematic sectional view showing a movement at the time of detachment of the workpiece from the polishing pad by raising the polishing head, in a position where there is no spacer; Fig. Figure 10 is a schematic basic view showing an example of a single-sided polishing device; Fig. Figure 11 is a schematic basic view showing an example of a conventional double-sided polishing device; Fig. Figures 12 are schematic sectional views showing an example of a method for assembling the polishing head according to the present invention; and Fig. Figure 13 is a schematic sectional view showing a second embodiment of the polishing head according to the present invention. BEST WAYS TO IMPLEMENT THE INVENTION

[0027] The present invention will now be explained in more detail.

[0028] As described above, when polishing a large-diameter workpiece using the polishing pad without the groove, a problem arises in that when lifting the polishing head in an attempt to detach the workpiece from the polishing pad after its polishing process (also known as separating or peeling off), the polished workpiece adheres to the surface of the polishing pad and thus remains on the polishing pad.

[0029] In view of the problems, the present inventors have carried out very precise investigations into a method for easily detaching the workpiece from the polishing pad without using the method of forming a groove on the polishing pad and also without using the shearing method.

[0030] Through their investigations, the inventors discovered that when the polishing head holding the workpiece is lifted, the workpiece can be released by applying a concentrated force to a specific area on a workpiece-holding surface of the carrier. This area holds the back side (the side opposite the surface to be polished) of the workpiece when the polishing head is tilted and lifted. Furthermore, the inventors found that when dressing is performed using a conventional method, a shape forms in the center of the polishing pad that is lower than its edge region, creating a depression.Furthermore, the present inventors are convinced that after polishing, at the time of detachment of the workpiece from the polishing pad, the workpiece can be more easily detached from the polishing pad by applying a force in the vicinity of the depression located in the center of the polishing pad, and have thereby come about the present invention.

[0031] A polishing head and a polishing device according to the present invention will now be explained in detail with reference to the accompanying figures. However, the present invention is not limited to this.

[0032] The Fig. Figure 1 shows an embodiment of the polishing head according to the present invention (a first embodiment). The polishing head 11 according to the present invention comprises a spacer 15, which will be explained later. First, the general structure is described. The polishing head 11 has a head body 12. A chamber 18 is formed within the head body 12. The head body 12 is rotatable and has a through-hole 20 for pressure adjustment, which is connected to a pressure adjustment device 19 arranged centrally on its upper part.

[0033] The head body 12 is connected by a membrane 14 to a disc-like support 13, which is arranged concentrically. Through this connection via the membrane 14, the head body 12 holds the support 13, and the space section 18 of the head body 12 is tightly sealed.

[0034] A device for vertical movement (not shown) causes the head body 12 to move in a vertical direction.

[0035] The support 13 is used to hold the back side (the side opposite the surface to be polished) of the workpiece W. For example, a support 13 with a flat holding surface, high rigidity, and which does not cause metallic contamination of the workpiece W can be used. Preferably, a circular plate made of ceramic, such as aluminum oxide, is used for the support. Alternatively, other supports, such as a so-called rubber clamping support, which will be described later, can also be used.

[0036] Furthermore, it is preferred that the diameter of the workpiece holding surface of the carrier 13 corresponds to a diameter of the workpiece W to be polished or is slightly larger than a diameter of the workpiece W in order to support the entire back side of the workpiece W.

[0037] A highly elastic material, such as elastomer or rubber, can preferably be used for the membrane 14. A film of the membrane 14, made from the material described above, is fixed to the head body 12 and the support 13 by screws and the like, so that the head body, the support, and the membrane are connected to each other and the space section 18 of the head body 12 is tightly sealed.

[0038] On the outside of the head body 12, an annular head body contact area 12a is formed, which projects outwards. On the support 13, an upwardly projecting, annular protruding section 13a and an annular support contact area 13b are formed. The outer diameter of the head body contact area 12a is larger than the inner diameter of the support contact area 13b. As shown in the Fig. As shown in Figure 9, when the head body 12 is lifted to detach the workpiece from the polishing pad, an annular contact surface of the head body contact area 12a and the support contact area 13b engage each other in a position where no spacer is present. Since the spacer 15 is provided, there is indeed an area with a gap between the head body contact area 12a and the support contact area 13b, although this area is not shown in the figure.

[0039] In order for the head body 12 to move vertically, the projecting section 13a of the support must extend further upwards than the head body contact area 12a, and its inner diameter must be larger than the outer diameter of the head body contact area 12a. A section within the projecting section 13a of the support 13 is not necessarily flat and may have a convex shape that enters the space of the head body 12.

[0040] The positional relationship between the head body 12 and the support 13, as described above, can be represented by the following: Fig. The methods shown in section 12 can be obtained, but the present invention is not limited to them.

[0041] As regards the support 13, a first part 13c, consisting of a part of the annular projecting section 13a and the support mounting area 13b, and a second part 13d, consisting of other sections, primarily a disk-shaped section, are prepared separately ( Fig. 12 (a)). Next, the head body 12 is placed on the second part 13d, to which the membrane 14 is attached by means of screws and the like ( Fig. 12 (b)). Then the first part 13c is attached to the second part 13d by means of screws and the like, as a result of which the support 13 is created ( Fig. 12 (c)). It should be noted that the membrane 14 can be attached to the support 13 using the same screws with which the first part 13c is fixed to the second part 13d.

[0042] It should be noted that when the support 13 and the head body 12 are connected between the aforementioned section 13a of the support 13 and the head body contact area 12a by the membrane 14, its construction becomes simpler and is therefore preferred. However, the present invention is not limited to this.

[0043] Preferably, an additional cushion 17 is provided on the surface (the holding surface) of the carrier 13 where the back of the workpiece W is held. The additional cushion 17, made of foamed polyurethane, is fixed to the holding surface of the carrier 13, for example, with double-sided adhesive tape or the like. By providing such an additional cushion 17 and allowing it to become saturated with water, the workpiece W can be held more securely by the surface tension of the water contained in the additional cushion 17.

[0044] A molded part 16 can be provided on a circumferential section of the carrier 13, i.e., outside the workpiece holding surface. The molded part 16 is used to hold an edge region of the workpiece W and is arranged such that it extends downwards along the circumferential section of the carrier 13. The molded part 16 holds the edge region of the workpiece so that the workpiece cannot detach from the carrier 13, and the molded part 16 does not press against the polishing pad 22. The molded part 16 is preferably made of a material that does not contaminate the workpiece W and is softer than the workpiece W to avoid causing scratches or marks.

[0045] A dressing ring (not shown) can be arranged on the circumference of the molded part 16, the dressing ring pressing against the polishing pad 22 during polishing to prevent wavy deformation of the polishing pad 22. The dressing ring preferably consists of a material that does not cause metallic contamination on the workpiece W and that exhibits minimal wear upon contact with the polishing pad 22. Preferably, for example, a ring made of aluminum oxide is used.

[0046] As in the Fig. As shown in Figure 1, the polishing head 11 according to the present invention is provided with a spacer 15 in the aforementioned general structure, which is arranged at least between the support contact area and the head body contact area in a portion of at least either the support contact area or the head body contact area. In the embodiment shown in the Fig. 1 is fixed to the support area 13b with screws and the like. It should be noted that the spacer 15, as shown in the Fig. Figure 2 shows the spacer attached to a portion of the annular support contact area 13b when viewed from above. The spacer can be made of any material, provided the material possesses a certain stiffness and does not deform easily. The size of the spacer 15 is not limited, as long as the spacer does not become unstable when it is placed against the head body contact area 12a. For example, the size of the spacer can be approximately one-tenth of the inner diameter of the support contact area 13b. Furthermore, the cross-sectional shape of the spacer 15 is also not limited, as long as the spacer is positioned between the support contact area 13b and the head body contact area 12a. For example, as shown in Figure 2, the spacer can be made of any material that does not deform easily. Fig. As shown in Figure 1, the spacer has a shape that encompasses the support mounting area 13b and is fixed from above by means of screws; it can be assumed that it is stable. However, the present invention is not limited to this.

[0047] As described below, when the beam 13 is lifted at an angle, the thickness of the spacer 15 is adjusted accordingly, for example, so that the angle of inclination of the beam is approximately 0.1 to 1°. The thickness of the spacer 15 is adjusted in a simple manner, preferably by preparing spacers of different thicknesses in advance and replacing them accordingly.

[0048] Since the spacer 15 does not touch the head body contact area 12a during polishing of the workpiece, the workpiece can be polished as well as with a general polishing head, without any change compared to a polishing head that does not have the spacer 15, and thus there is no problem regarding the polishing quality of the workpiece.

[0049] Fig. Figure 13 shows the polishing head, in which the support is a rubber tension support, as a second embodiment of the polishing head according to the present invention.

[0050] The polishing head 61 mainly comprises the head body 12 and the rubber tensioning support 62, which is connected to the head body 12 by the membrane 14. Through this connection by means of the membrane 14, the head body 12 holds the rubber tensioning support 62, the chamber section 18 is tightly sealed, and the through-hole 20 for pressure adjustment, which is connected to the pressure adjustment device 19, is provided in the center of the upper part of the head body 12, as in the previous first embodiment.

[0051] The rubber clamping carrier 62 has an upper support part 63 and a rubber part 65, which is connected with uniform tension to an annular, rigid ring 64 made of a rigid material such as SUS (stainless steel) or the like, and has a flat underside. The workpiece holding surface W is the underside of the rubber part 65. The rubber clamping carrier also has a workpiece pressure chamber 66 on the side opposite the workpiece holding surface of the rubber part 65. A fluid is supplied to the workpiece pressure chamber 66 through a fluid supply channel 68, which is connected to a pressure adjustment device 67 to exert pressure on the workpiece.The rubber part 65 can be subjected to uniform pressure by supplying compressed air to the workpiece pressure chamber 66 via the pressure adjusting device 67, thus exerting pressure on the workpiece. The workpiece can then be pressed with uniform pressure against the polishing pad 22 located on the rotary table 21. Creating a vacuum in the workpiece pressure chamber 66 with the pressure adjusting device 67 to press the workpiece allows the workpiece W to be drawn onto the rubber part 65. Additionally, the auxiliary pad 17 can be provided on the underside of the rubber part 65, and this auxiliary pad 17 can also draw the workpiece W into contact with the rubber part. Furthermore, the molded part 16 can be provided.

[0052] The preceding section 63a and the support mounting area 63b are formed on the upper support part 63. As in the preceding first embodiment, the spacer 15 is provided such that the spacer 15 is located at least between the support mounting area 63b and the head body mounting area 12a in a partial area of ​​at least either the support mounting area 63b or the head body mounting area 12a.

[0053] In addition to the rubber tensioning device with a typical structure as described above, various conventionally known rubber tensioning devices can be used.

[0054] The Fig. Figure 3 shows a rough drawing of a polishing device 31, which is equipped with the polishing head 11 described above according to the present invention. The polishing device 31 comprises the polishing pad 22 attached to the rotary plate 21, and, in addition to the polishing head 11, a polishing agent supply device 36 for supplying a polishing agent 35 to the polishing pad 22.

[0055] Before polishing the workpiece W using the polishing device 31, the polishing pad 22 is first dressed or smoothed. This dressing is carried out as usual using an ordinary dresser, as described in the Fig. 7 (a) is shown.

[0056] Normally, at least one area where the workpiece has sliding contact during its polishing process is dressed using a dresser that is larger than the workpiece to be polished.

[0057] For example, a wheel dresser 41 is used as a dresser, in which the outer diameter of a section bearing against the polishing pad 22 is slightly larger than the radius of the rotary table 21, and its inner diameter is slightly smaller than the radius of the rotary table 21 (for example, when polishing a silicon wafer with a diameter of 300 mm using a rotary table with a diameter of 800 mm, the outer diameter of the section bearing against the polishing pad is approximately 410 mm, and its inner diameter is approximately 380 mm). Dressing is performed with the wheel dresser 41 by clamping the wheel dresser 41 in place and rotating the rotary table 21 while the wheel dresser is bearing against the polishing pad 22. In this case, the wheel dresser 41 can be rotated and pivoted in the diameter direction of the rotary table 21 with an amplitude of approximately one-tenth of the radius of the rotary table.

[0058] As mentioned above, the present inventors have found that when dressing is carried out using a normal method as described above, the polishing pad assumes a shape that is deeper in the middle than at the outer edge, and as in the Fig. Figure 7(b) shows a depression. It should be noted that the diagram in the Fig. 7 (b) shows the height distribution of the polishing pad in the diameter direction of the turntable and two curves in the diagram show height distributions of the polishing pad in two mutually perpendicular directions in an upper plane of the turntable.

[0059] It can be assumed that this is due to the fact that the oscillation period at the dresser is longer near the center of the polishing pad than at the circumference when dressing is done using the wheel dresser.

[0060] After the conventional dressing process described above, the workpiece W is polished using the polishing device 31, which is provided with the polishing head 11 according to the present invention.

[0061] When the workpiece W is polished using the polishing device 31, the workpiece W is first held with the carrier 13, e.g. by attaching it to the additional cushion 17 which contains water to hold the back of the workpiece W in place, and the edge area of ​​the workpiece W is held with the molded part 16.

[0062] The polishing compound 35 is then supplied to the polishing pad 22 by the polishing compound feed device 36, while the workpiece W is in sliding contact with the polishing pad 22, with the polishing head 11 and the rotary table 21 rotating in their respective prescribed directions. At this time, the diaphragm 14 can be elastically deformed by adjusting the pressure of the tightly sealed chamber 18 of the head body 12 using the pressure adjustment device 19. For example, if compressed air is supplied to the chamber 18 by the pressure adjustment device 19, the diaphragm 14 deforms elastically between the head body 12 and the support 13, and the support 13 is pressed against the side of the polishing pad 22 with a prescribed pressure.In this way, the front of the workpiece W can be polished by elastic deformation of the membrane 14 by means of the pressure adjustment device 19, while the workpiece W, held by the carrier 13, is pressed against the polishing pad 22 located on the rotary table 21 with a prescribed pressure force and the workpiece W is rotated in relation to the polishing pad 22.

[0063] It should be noted that the depression in the immediate vicinity of the center of the polishing pad 22 flattens out so much due to the pressure of the workpiece W that it can be disregarded when polishing the workpiece W; there is no problem with regard to the polishing quality of the workpiece.

[0064] Furthermore, the workpiece W can be polished with the polishing head 11 in such a way that it is swivelled during the polishing of the workpiece W.

[0065] After the workpiece W has been dressed and polished as described above, the workpiece W is removed from the polishing pad 22 by the following procedure.

[0066] First, the rotation of the polishing head 11 is stopped so that the spacer 15 is located near the recess formed in the central section of the polishing pad 22. More precisely, as shown in the Fig. As shown in Figure 6, the rotation of the polishing head 11 is stopped such that the rotational position of the spacer 15 is within 30° of the center of the polishing head 11 (specifically, the center of the turntable 21) with respect to the center of the polishing pad 22. More preferably, the rotational position of the spacer 15 is within 15° of the center of the polishing pad 22, as seen from the center of the polishing head 11, and most preferably, it lies on a line connecting the center of the polishing head 11 with the center of the polishing pad 22.

[0067] A method for stopping the rotational position of the polishing head 11 in the aforementioned prescribed position is not limited, but automatic stopping in the prescribed position is easily feasible and therefore desirable. For this reason, the polishing device 31 is preferably equipped with a device for automatically setting the rotational stop position of the polishing head 11 (for example, with a servo device or the like).

[0068] After stopping the rotation of the polishing head 11, as described above, the workpiece W is detached from the polishing pad 22 by lifting the head body 12 as follows.

[0069] First, as in the Fig. As shown in Figure 4, the head body 12 is raised, and consequently, the spacer 15 rests against the head body's contact area 12. If the lifting force continues in this state, the spacer 15 is subjected to a force that then acts on a region of the workpiece holding surface of the carrier 13, with this region located directly below the spacer 15. If the spacer 15 is located near the center of the polishing pad 22, with a slight depression in this area, then the region of the workpiece holding surface of the carrier 13 on which the force is focused is also located near the center of the polishing pad 22, with a slight depression in this area. Therefore, the workpiece W can be easily and stably removed from the polishing pad 22.

[0070] When the polishing head is raised further, it supports itself, as in the Fig. 5 shows the head body contact area 12a at the spacer 15 and at the section of the ring-shaped support contact area 13b opposite the spacer 15, and the support 13 is lifted at an angle.

[0071] It is important to note that the thickness of the spacer 15 must be adjusted appropriately so that the workpiece W detaches consistently from the polishing pad 22. As described above, when lifting the carrier 13 at an angle, the thickness of the spacer 15 can be adjusted so that the angle of inclination is approximately 0.1 to 1°.

[0072] It should be noted that the effects of the present invention can be achieved as long as the workpiece to be polished is not considerably smaller than the dressing area, since the circumferential section of the workpiece lies in the area of ​​the recess near the center of the polishing pad.

[0073] Furthermore, once the dressing has been carried out, the effects of the present invention can also be achieved if the polishing of the workpiece and the removal from the polishing pad are repeated within a normal span without dressing.

[0074] In the preceding explanation, the spacer with which the polishing head of the present invention is provided is attached to the support mounting area 13b. However, the spacer 15 can also be, as shown in the Fig. 8 is shown, attached to the head body mounting area 12a or both to the support mounting area 13b and to the head body mounting area 12a.

[0075] Examples and a comparative example of the present invention are explained below. (Example 1)

[0076] The one like in the Fig. The assembled polishing head 61 was manufactured as follows. A head body 12 made of stainless steel and a carrier 63 were prepared, in which the workpiece holding surface is formed by the rubber part 65, the workpiece pressure chamber 66 is provided on the back of the rubber part, and the rubber part 65 can be subjected to a uniform pressure by supplying compressed air to the workpiece pressure chamber 66 via the pressure adjusting device 67. The elements were connected to each other by the diaphragm 14.

[0077] A silicon wafer with a diameter of 300 mm and a thickness of 775 µm was used as the workpiece, as described below. Fig. 3 polishing device 31 shown, which was equipped with the polishing head 61 described above (the Fig. Figure 3 shows an embodiment in which the polishing head 11 of the Fig. 1 is provided, in this example an embodiment with polishing head 61). The silicon wafer used was previously subjected to a first polishing process on both sides, whereby its edge region was also polished. A rotary table 21 with a diameter of 800 mm and a conventional polishing pad 22, which has no groove, were used.

[0078] Before polishing, the polishing pad 22 was first dressed. The wheel dresser 41 was used, with an outer diameter of 410 mm and an inner diameter of 380 mm at the bottom. The wheel dresser 41 was pressed down with a pressure of 30 kPa, the rotary table 21 rotated at 29 rpm, and the dressing process was carried out for 180 minutes.

[0079] An alkaline solution containing colloidal silicon dioxide was used as the polishing agent, and the polishing head 11 and the rotary table 21 were rotated at 31 rpm and 29 rpm, respectively. A polishing pressure (pressure force) for the workpiece W was set to 15 kPa. The polishing time was 10 minutes.

[0080] After the workpiece polishing process was completed, the rotation of the polishing head 11 was stopped so that the rotational position of the spacer 15 (with a thickness of 2 mm) was within 30° of the center of the polishing head 11 and the center of the polishing pad 22. The polishing head 12 was raised in the rotational position so that the pressure (the pressure of the workpiece clamping chamber 66; suction pressure) acting between the workpiece W and the suction surface of the carrier 13 (the rubber part) reached a value of -45 kPa, and the workpiece detached within 2 seconds.

[0081] The polishing and removal from the polishing pad were repeated with 300 workpieces, half of which were without a dressing process.

[0082] As a result, 300 of the 300 workpieces could be removed normally (success rate 100%), thus clearly achieving the effects of the present invention. (Example 2)

[0083] The removal from the polishing pad was tested as in Example 1 with 26 workpieces, except that the rotation of the polishing head was stopped without setting the stop position of the spacer, and the polishing head body 12 was lifted in the rotation position after polishing the workpiece.

[0084] As a result, 24 of the 26 workpieces could be removed without any problems; however, an unusual noise occurred when two workpieces were removed. (Comparative example 1)

[0085] As in Example 1, silicon wafers were polished using the same polishing device equipped with the same polishing head as in Example 1, except that no spacer was used. Removal was attempted with a suction pressure of -30 kPa for 1 to 2 seconds.

[0086] The result was that the turntable was lifted and the workpiece could therefore not be removed.

[0087] The present invention is not limited to the embodiment mentioned above. The embodiment described above is merely an exemplary representation, and all embodiments according to the claims are included within the technical scope of the present invention. For example, the feature of the polishing device is not limited to one that is included in the Fig. Figure 3 shows that the polishing device can, for example, have several polishing heads according to the present invention.

Claims

[1] Polishing head (11) with at least one disc-shaped support (13) for holding a rear side of a workpiece (W), in which an annular projecting section (13a) which projects upwards and an annular support contact area (13b) which projects inwards from the projecting section (13a) are formed on a circumferential section, a head body (12) for holding the carrier, in which an internal space section (18) is formed, and an outwardly projecting, ring-shaped head body contact area (12a) formed on the outside, wherein the head body (12) is rotatable, and a membrane (14) for connecting the head body (12) to the support (13) and for tightly sealing the space section of the head body (12); wherein the polishing head (11) holds the back of the workpiece (W) with the carrier (13) in the state in which a pressure of the tightly sealed chamber section (18) is set by means of a pressure adjusting device connected to the chamber section (18), when a front of the workpiece is polished by bringing it into sliding contact with a polishing pad (22) attached to a rotary table, and the workpiece (W) is detached from the polishing pad (22) by lifting the head body (12) and the support contact area (13b), wherein the support contact area (13b) and the head body contact area (12a) interlock when the workpiece (W) is detached from the polishing pad (22) by lifting the polishing head (11) after polishing the workpiece (W); wherein a spacer (15) is provided at least between the support area (13b) and the head body support area (12a) in a part of the support area (13b) and / or the head body support area (12a), and the spacer (15) is supported on the support area (13b) and on the head body support area (12a) when the head body (12) is lifted, so that the workpiece (W) is released from the polishing pad (22) by lifting the support (13) at an angle when the workpiece is released from the polishing pad (22) by lifting the polishing head (11), wherein a thickness of the spacer (15) is adjustable in order to set an angle of inclination when lifting the polishing head (11). [2] Polishing head (11) according to claim 1, comprising an additional pad (17) on a surface of the carrier (13), wherein the surface holds the back of the workpiece (W). [3] Polishing head (11) according to claim 1 or claim 2, wherein the carrier (13) is able to hold a semiconductor wafer with a diameter of 300 mm or more as a workpiece. [4] Polishing device used for polishing a surface of a workpiece, comprising at least the following: a polishing pad attached to a rotary plate; a polishing agent supply device for supplying a polishing agent to the polishing pad; and a polishing head (11) for holding the workpiece, the polishing head (11) being that according to any one of claims 1 to 3. [5] Polishing device according to claim 4, comprising a device for automatically setting a rotation stop position of the polishing head (11) [6] Method for removing a workpiece from a polishing pad after dressing the polishing pad attached to a rotary table, and for bringing a surface of the workpiece into sliding contact with the dressed polishing pad for polishing, comprising the following steps: Holding and polishing the workpiece with the polishing head (11) according to one of claims 1 to 3; Stopping the rotation of the polishing head (11) such that a rotational position of the spacer is within 30° of a center point of the polishing head (11) with respect to a center point of the polishing pad; and Detaching the workpiece by lifting the head body (12) in the rotating position.

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