EDGE POLISHING DRUM OF WAFER, EDGE POLISHING EQUIPMENT INCLUDING THE SAME, AND METHOD FOR POLISHING EDGE OF WAFER

Abstract

Disclosed are a wafer edge polishing drum, wafer edge polishing equipment including the same, and a wafer edge polishing method. The wafer edge polishing drum includes a plurality of first polishing units provided at a first body portion, a plurality of second polishing units provided at a second body portion located below the first body portion, a driving unit configured to rotate the first body portion and the second body portion, a plurality of third polishing units provided at least at one of the first body portion or the second body portion, and a controller. Each of the first to third polishing units includes a central shaft, a weight connected to one side of the central shaft, and a polishing portion connected to the opposite side of the central shaft. The controller is configured to adjust a distance between the central shaft and the weight.

Claims

1. A wafer edge polishing drum, comprising: a plurality of first polishing units provided at a first body portion; a plurality of second polishing units provided at a second body portion located below the first body portion; a driving unit configured to rotate the first body portion and the second body portion; a plurality of third polishing units provided at least at one of the first body portion or the second body portion; and a controller, wherein each of the plurality of first to third polishing units includes: a central shaft; a weight connected to one side of the central shaft; and a polishing portion connected to an opposite side of the central shaft, and wherein the controller is configured to adjust a distance between the central shaft and the weight.

2. The wafer edge polishing drum according to claim 1, wherein the first and second body portions are connected to each other via a connecting portion so as to rotate together.

3. The wafer edge polishing drum according to claim 1, wherein each of the plurality of first to third polishing units includes: a first connecting portion connecting the weight to the central shaft; and a second connecting portion connecting the polishing portion to the central shaft.

4. The wafer edge polishing drum according to claim 1, wherein the first polishing units polish an upper surface of an edge region of a wafer, the second polishing units polish a lower surface of the edge region of the wafer, and the third polishing units polish a side surface of the edge region of the wafer.

5. The wafer edge polishing drum according to claim 1, wherein the central shaft is a servomotor, and wherein the servomotor and the weight are coupled to each other using a screw.

6. The wafer edge polishing drum according to claim 1, wherein the central shaft is an air cylinder, and wherein a distance between the weight and the air cylinder is changed by pressurization of the air cylinder.

7. The wafer edge polishing drum according to claim 1, wherein, in each of the plurality of first polishing units, the central shaft is fixed to the first body portion, the weight is disposed above the first body portion, and the polishing portion is disposed below the first body portion.

8. The wafer edge polishing drum according to claim 1, wherein, in each of the plurality of second polishing units, the central shaft is fixed to the second body portion, the weight is disposed below the second body portion, and the polishing portion is disposed above the second body portion.

9. The wafer edge polishing drum according to claim 1, wherein, in each of the plurality of third polishing units, the central shaft is fixed to the first body portion or the second body portion, the weight is disposed above the first body portion or below the second body portion, and the polishing portion is disposed below the first body portion or above the second body portion.

10. The wafer edge polishing drum according to claim 1, wherein each of the plurality of first to third polishing units is provided in four, and wherein the plurality of first to third polishing units is alternately disposed in sequence along a periphery of a wafer disposed between the first body portion and the second body portion.

11. The wafer edge polishing drum according to claim 1, wherein each of the plurality of first and second polishing units includes a polishing pad provided on the polishing portion, and wherein the polishing pad has a polishing surface inclined with respect to an axis interconnecting the first body portion and the second body portion.

12. The wafer edge polishing drum according to claim 1, wherein each of the plurality of third polishing units includes a polishing pad, and wherein the polishing pad has a polishing surface parallel to an axis interconnecting the first body portion and the second body portion.

13. The wafer edge polishing drum according to claim 1, wherein the plurality of first polishing units and the plurality of second polishing units are disposed symmetrically with each other with respect to a center of a region of a wafer to be polished between the first body portion and the second body portion.

14. The wafer edge polishing drum according to claim 1, wherein each of the plurality of first to third polishing units includes a polishing pad, and wherein the polishing pad of each of the first and second polishing units has different shape from the polishing pad of each of the third polishing units.

15. Wafer edge polishing equipment, comprising: the wafer edge polishing drum according to claim 1; and a wafer support chuck disposed to face a lower surface of the second body portion of the wafer edge polishing drum, the wafer support chuck being spaced apart from the lower surface of the second body portion.

16. The wafer edge polishing equipment according to claim 15, wherein the first body portion and the second body portion are configured to rotate about a first rotation axis interconnecting the first body portion and the second body portion, wherein the wafer support chuck is configured to rotate about a second rotation axis, and wherein the first rotation axis and the second rotation axis coincide with each other.

17. The wafer edge polishing equipment according to claim 16, wherein the wafer support chuck includes: a rotary body rotating about the second rotation axis; and a support body rotating along with rotation of the rotary body and supporting a wafer.

18. A wafer edge polishing method, comprising: receiving a target profile of an edge region of a wafer; determining amounts of polishing of an upper surface, a lower surface, and a side surface of the edge region of the wafer based on the target profile; and polishing the upper surface, the lower surface, and the side surface of the edge region of the wafer using different polishing pads, wherein the different polishing pads are provided in a plurality of first to third polishing units, respectively, and wherein pressures applied by the different polishing pads according to rotation of the plurality of first to third polishing units differ from each other.

19. The wafer edge polishing method according to claim 18, wherein each of the plurality of first to third polishing units includes: a central shaft; a weight connected to one side of the central shaft; and a polishing portion connected to an opposite side of the central shaft, each of the different polishing pads being provided on the polishing portion, and wherein, by adjusting a distance between the central shaft and the weight in each of the plurality of first to third polishing units, centrifugal force generated by rotation of the weight is varied.

20. The wafer edge polishing method according to claim 19, wherein, when the centrifugal force generated by rotation of the weight is varied, pressure applied by each of the different polishing pads is varied.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the principle of the disclosure. In the drawings:

[0031] FIG. 1 is a view showing wafer edge polishing equipment according to an embodiment of the present disclosure;

[0032] FIGS. 2A to 2C are views showing changes in the distance between a central shaft and a weight according to rotation of a first polishing unit provided in the wafer edge polishing equipment shown in FIG. 1;

[0033] FIG. 3 is a view showing a third polishing unit provided in the wafer edge polishing equipment shown in FIG. 1;

[0034] FIG. 4 is a view showing arrangement of the first to third polishing units in the wafer edge polishing equipment;

[0035] FIGS. 5 and 6 are views showing variations in the pressure applied to an edge region of a wafer by a polishing pad according to changes in the distance between the central shaft and the weight in each of the first and second polishing units; and

[0036] FIG. 7 is a flowchart of a wafer edge polishing method according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0037] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which various embodiments are shown.

[0038] The examples, however, may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will more fully convey the scope of the disclosure to those skilled in the art.

[0039] In addition, relational terms, such as first, second, on/upper part/above and under/lower part/below, are used only to distinguish between one subject or element and another subject or element, without necessarily requiring or involving any physical or logical relationship or sequence between the subjects or elements.

[0040] According to a wafer edge polishing drum, wafer edge polishing equipment including the same, and a wafer edge polishing method of the present disclosure, each of first to third polishing units includes a central shaft, a weight connected to one side of the central shaft, and a polishing portion connected to the opposite side of the central shaft, and distances between the central shafts and the weights are adjusted according to a target profile of an edge region of a wafer. Accordingly, pressures applied to a front bevel, a back bevel, and an apex of the edge region of the wafer by first to third polishing pads may be varied, so that the edge region of the wafer may be polished in accordance with the target profile.

[0041] FIG. 1 is a view showing wafer edge polishing equipment according to an embodiment of the present disclosure.

[0042] The wafer edge polishing equipment 1000 according to an embodiment of the present disclosure may include a wafer edge polishing drum 100 and a wafer support chuck 200 disposed to face a lower surface of a second body portion 120 of the wafer edge polishing drum 100 while being spaced apart therefrom.

[0043] The wafer edge polishing drum 100 for polishing a wafer may rotate about a first rotation axis (first axis), and the wafer support chuck 200 for supporting the wafer may rotate about a second rotation axis (second axis).

[0044] The wafer edge polishing drum 100 for polishing the wafer and the wafer support chuck 200 for supporting the wafer may rotate in the same direction, as shown in FIG. 1, or may rotate in different directions. In this case, the first rotation axis of the wafer edge polishing drum 100 and the second rotation axis of the wafer support chuck 200 may coincide with each other.

[0045] The wafer support chuck 200 may include a rotary body 220 and a support body 210. The rotary body 220 is a portion that rotates about the aforementioned second rotation axis, and the support body 210 is a portion that rotates along with rotation of the rotary body 220 and supports the wafer.

[0046] The wafer edge polishing drum 100 may include a first body portion 110, a plurality of first polishing units 140 provided at the first body portion 110, a second body portion 120 located below the first body portion 110, and a plurality of second polishing units 150 provided at the second body portion 120. The first and second body portions 110 and 120 may be connected to each other via a connecting portion 130 so as to rotate together.

[0047] Although not shown, a driving unit may be provided to rotate both the first body portion 110 and the second body portion 120 about the first rotation axis.

[0048] The wafer edge polishing drum 100 may include first to third polishing units. The first polishing unit 140 may be provided at the first body portion 110, and the second polishing unit 150 may be provided at the second body portion 120. The first polishing unit 140 and the second polishing unit 150 may have the same shape. The third polishing unit may be provided at the first body portion 110 or the second body portion 120, which will be described later with reference to FIG. 3.

[0049] FIGS. 2A to 2C are views showing changes in the distance between a central shaft and a weight according to rotation of the first polishing unit provided in the wafer edge polishing equipment shown in FIG. 1, and FIG. 3 is a view showing the third polishing unit provided in the wafer edge polishing equipment shown in FIG. 1. Hereinafter, the first to third polishing units provided in the wafer edge polishing equipment shown in FIG. 1 will be described with reference to FIGS. 2A to 2C and FIG. 3.

[0050] Referring to FIG. 2A, each of the plurality of first polishing units 140 may include a central shaft 141, a weight 143 connected to one side of the central shaft 141 via a first connecting portion 142, a polishing portion 145 connected to the opposite side of the central shaft 141 via a second connecting portion 144, and a polishing pad 148 provided on a surface of the polishing portion 145.

[0051] Although not shown, a controller may be provided in the first polishing unit 140 to adjust the distance between the central shaft 141 and the weight 143.

[0052] As shown in FIG. 2A, the central shaft 141 and the weight 143 are spaced a first distance a0 from each other, and the central shaft 141 and the polishing portion 145 are spaced a second distance b from each other. In this case, the first distance a0 is a distance between the central portion of the central shaft 141 and the central portion of the weight 143, and the second distance b is a distance between the central portion of the central shaft 141 and the central portion of the polishing portion 145.

[0053] As described above, the controller may adjust the first distance a0 between the central shaft 141 and the weight 143 in the first polishing unit 140. That is, the controller may perform control such that the first distance a0 between the central shaft 141 and the weight 143 in the first polishing unit 140 is reduced to a1, as shown in FIG. 2B, or may perform control such that the first distance a0 between the central shaft 141 and the weight 143 in the first polishing unit 140 is increased to a2, as shown in FIG. 2C.

[0054] In order to achieve adjustment of the first distance by the above-described controller, the central shaft 141 is implemented as a servomotor, and the first connecting portion 142 is implemented as a screw. The servomotor is connected to the weight 143 via the screw, and the screw rotates along with rotation of the servomotor, thereby reducing the aforementioned first distance from a0 to a1 or increasing the same from a0 to a2.

[0055] Alternatively, in another embodiment, the central shaft 141 is implemented as an air cylinder, and the length of the first connecting portion is changed by pressurization of the air cylinder, thereby reducing the aforementioned first distance from a0 to a1 or increasing the same from a0 to a2.

[0056] The second polishing unit 150 may have the same configuration as the first polishing unit 140. As shown in FIG. 1, the second polishing unit 150 may be provided to be inverted in an upward-downward direction with respect to the first polishing unit 140. Accordingly, as shown in FIG. 1, the first polishing unit 140 may polish a back bevel, which is a lower surface of an edge region of the wafer, and the second polishing unit 150 may polish a front bevel, which is an upper surface of the edge region of the wafer.

[0057] That is, referring to FIG. 1, in the first polishing unit 140, the central shaft may be fixed to the first body portion 110, the weight may be disposed above the first body portion 110, and the polishing portion may be disposed below the first body portion 110.

[0058] In addition, referring to FIG. 1, in the second polishing unit 150, the central shaft may be fixed to the second body portion 120, the weight may be disposed below the second body portion 120, and the polishing portion may be disposed above the second body portion 120.

[0059] An apex, which is a side surface of the edge region of the wafer, may be polished by the third polishing unit. FIG. 3 is a view showing the third polishing unit provided in the wafer edge polishing equipment shown in FIG. 1.

[0060] Each of the plurality of third polishing units 160 may include a central shaft 161, a weight 163 connected to one side of the central shaft 161 via a first connecting portion 162, a polishing portion 165 connected to the opposite side of the central shaft 161 via a second connecting portion 164, and a polishing pad 168 provided on a surface of the polishing portion 165.

[0061] In addition, similar to the first polishing unit 140 described above with reference to FIGS. 2A to 2C, the third polishing unit 160 may be configured such that the central shaft 161 is implemented as a servomotor or a pressurizing cylinder, and a distance from the central shaft 161 to the weight 163 is varied, so that pressure applied to the wafer by the polishing pad 168 is varied. However, in the third polishing unit 160 of this embodiment, the distance from the central shaft 161 to the weight 163 may be kept constant, so that the apex portion of the edge region of the wafer is polished with a constant pressure.

[0062] Further, because the third polishing unit 160 applies pressure to the apex portion, which is the side surface of the edge region of the wafer, the polishing portion 165 and the polishing pad 168 may have different shapes from the polishing portions and the polishing pads of the first and second polishing units 140 and 150, as shown in FIG. 3.

[0063] That is, referring to FIG. 1, polishing surfaces of the polishing pads 148 and 158 provided on the polishing portions 145 and 155 of the first and second polishing units 140 and 150 are inclined with respect to an axis (parallel to the first rotation axis) interconnecting the first body portion 110 and the second body portion 120. This is because the polishing pads 148 and 158 polish the back bevel and the front bevel of the edge region of the wafer, respectively.

[0064] However, a polishing surface of the polishing pad 168 provided on the polishing portion 165 of the third polishing unit 160 is parallel to the axis (parallel to the first rotation axis) interconnecting the first body portion 110 and the second body portion 120. This is because the polishing pad 168 polishes the apex portion of the edge region of the wafer.

[0065] The third polishing unit 160 may be provided at the first body portion 110 or the second body portion 120 shown in FIG. 1. In detail, in the third polishing unit, the central shaft may be fixed to the first body portion 110, the weight may be disposed above the first body portion 110, and the polishing portion may be disposed below the first body portion 110. Alternatively, the central shaft may be fixed to the second body portion 120, the weight may be disposed below the second body portion 120, and the polishing portion may be disposed above the second body portion 120. In any case, the polishing pad 168 may be disposed adjacent to an edge of the apex portion, which is the side surface of the edge region of the wafer.

[0066] FIG. 4 is a view showing arrangement of the first to third polishing units in the wafer edge polishing equipment. As shown in FIG. 4, four first polishing units, four second polishing units, and four third polishing units may be provided, and the first to third polishing units may be alternately disposed in sequence around the edge region of the wafer.

[0067] When the wafer has a diameter of 300 millimeters, the edge region may have a width of about 1 millimeter.

[0068] As shown, one first polishing unit, one second polishing unit, and one third polishing unit may be disposed in each of first to fourth quadrants.

[0069] Referring to FIGS. 2A to 2C, the states of the first and second polishing units 140 and 150 in which the first distance from the central shaft to the weight is reduced to a1 are denoted by 140a and 150a, respectively, and the states of the first and second polishing units 140 and 150 in which the first distance from the central shaft to the weight is increased to a2 are denoted by 140b and 150b, respectively.

[0070] Referring to FIG. 4, in the clockwise direction, the third polishing unit 160, the first polishing unit 140a, and the second polishing unit 150a may be sequentially disposed in the first quadrant, the third polishing unit 160, the first polishing unit 140b, and the second polishing unit 150b may be sequentially disposed in the second quadrant, the third polishing unit 160, the first polishing unit 140a, and the second polishing unit 150a may be sequentially disposed in the third quadrant, and the third polishing unit 160, the first polishing unit 140b, and the second polishing unit 150b may be sequentially disposed in the fourth quadrant.

[0071] FIGS. 5 and 6 are views showing variations in the pressure applied to the edge region of the wafer by the polishing pad according to changes in the distance between the central shaft and the weight in each of the first and second polishing units. The first polishing unit and the second polishing unit may be disposed symmetrically with each other with respect to the center of a region of the wafer to be polished between the first body portion and the second body portion. When the wafer and the first and second polishing units rotate together, the first and second polishing units polish the front bevel and the back bevel of the entire edge region of the wafer. Therefore, in order to equally polish the front bevel and the back bevel of the wafer, the first and second polishing units having the same configuration need to be used together.

[0072] FIG. 5 shows a state in which, as shown in FIG. 2B, the first distance between the central shaft 141 and the weight 143 in the first polishing unit 140 is reduced to a1, and the first distance between the central shaft 151 and the weight 153 in the second polishing unit 150 is reduced to b1.

[0073] FIG. 6 shows a state in which, as shown in FIG. 2C, the first distance between the central shaft 141 and the weight 143 in the first polishing unit 140 is increased to a2, and the first distance between the central shaft 151 and the weight 153 in the second polishing unit 150 is increased to b2.

[0074] Referring to FIG. 5, because the first distances a1 and b1 between the central shafts 141 and 151 and the weights 143 and 153 in the first and second polishing units 140 and 150 are relatively short, centrifugal forces generated by the weights when the first and second body portions rotate may be relatively small. That is, when the first and second body portions rotate, the weights 143 and 153 also rotate with respect to the central shafts 141 and 151, thereby generating centrifugal forces F as will be described below.

F=(mv.sup.2)/r

[0075] Here, m represents mass of the weight, v represents velocity of the weight, and r represents distance from the rotation axis to the weight, which is identical to a1.

[0076] Accordingly, pressures applied to the back bevel and the front bevel of the edge region of the wafer by the polishing pads 148 and 158 may also be relatively small, and thus amounts of polishing of the back bevel and the front bevel of the edge region of the wafer may be small.

[0077] However, referring to FIG. 6, because the first distances a2 and b2 between the central shafts 141 and 151 and the weights 143 and 153 in the first and second polishing units 140 and 150 are relatively long, centrifugal forces generated by the weights when the first and second body portions rotate may be relatively large. Accordingly, pressures applied to the back bevel and the front bevel of the edge region of the wafer by the polishing pads 148 and 158 may be relatively large, and thus amounts of polishing of the back bevel and the front bevel of the edge region of the wafer may be large.

[0078] FIG. 7 is a flowchart of a wafer edge polishing method according to an embodiment of the present disclosure.

[0079] First, a target profile of an edge region of a wafer is input (S110). A plurality of wafers accommodated in a single cassette may be polished to the same profile, and therefore, the target profile of the edge region may be input before polishing the plurality of wafers in the single cassette.

[0080] Subsequently, amounts of polishing of an upper surface, a lower surface, and a side surface of the edge region of the wafer may be determined based on the input profile (S120).

[0081] Subsequently, the upper surface (front bevel), the lower surface (back bevel), and the side surface (apex) of the edge region of the wafer may be polished using different polishing pads provided in the wafer edge polishing equipment including the wafer edge polishing drum described above with reference to FIGS. 1 to 6 (S130).

[0082] In this case, the different polishing pads may be respectively provided in the plurality of first to third polishing units, and pressures applied by the respective polishing pads according to rotation of the first to third polishing units may differ from each other, so that amounts of polishing of the upper surface, the lower surface, and the side surface of the edge region of the wafer may be controlled.

[0083] Although it has been described with reference to FIG. 3 that the distance from the central shaft 161 to the weight 163 in the third polishing unit 160 is kept constant to polish the apex portion of the edge region of the wafer with a constant pressure, an amount of polishing of the side surface of the edge region of the wafer may also be controlled according to the method of the present disclosure.

[0084] A principle by which pressures applied by the respective polishing pads according to rotation of the first to third polishing units differ from each other is as follows.

[0085] In the first to third polishing units, as the distances between the central shafts and the weights are changed differently, centrifugal forces generated by rotation of the weights may be varied (S132).

[0086] That is, in the first to third polishing units, because the weights also rotate with respect to the central shafts, centrifugal forces F are generated as follows.

[00001]$F=\left(m{v}^2\right)/r$

[0087] Here, m represents mass of the weight, v represents velocity of the weight, and r represents distance from the rotation axis to the weight, which is identical to a1.

[0088] That is, when the first to third polishing units rotate, the weights provided in the respective polishing units are subjected to an outward force due to centrifugal forces, and at this time, the polishing pads move inward, so that the upper surface, the lower surface, and the side surface of the edge region of the wafer may be polished by the polishing pads.

[0089] When the centrifugal forces generated by rotation of the weights vary, the pressures applied to the upper surface, the lower surface, and the side surface of the edge region of the wafer by the polishing pads provided in the polishing units may also be varied (S134), thereby controlling the amounts of polishing of the upper surface, the lower surface, and the side surface of the edge region of the wafer. In addition, as the weights are positioned farther from the central shafts, the centrifugal forces may increase, and accordingly, the degree of polishing by the polishing pads may also increase.

[0090] According to the wafer edge polishing drum, the wafer edge polishing equipment including the same, and the wafer edge polishing method of the present disclosure described above, the front bevel, the back bevel, and the apex of the edge region of the wafer may be respectively polished by different polishing units, and the distances from the central shafts to the weights in the respective polishing units may be adjusted according to the target profile of the edge region of the wafer. Therefore, centrifugal forces generated by rotation of the weights when the polishing units rotate may vary, and accordingly, pressures applied to the portions of the edge region of the wafer to be polished by the polishing pads may be adjusted. As a result, the roll-off amount of the edge region of the wafer may be controlled in accordance with the target profile.

[0091] As is apparent from the above description, according to the wafer edge polishing drum, the wafer edge polishing equipment including the same, and the wafer edge polishing method of the present disclosure, a front bevel, a back bevel, and an apex of an edge region of a wafer may be respectively polished by different polishing units, and distances from central shafts to weights in the respective polishing units may be adjusted according to a target profile of the edge region of the wafer, thereby causing centrifugal forces generated by rotation of the weights when the polishing units rotate to vary. Accordingly, pressures applied to portions of the edge region of the wafer to be polished by polishing pads may be adjusted, thereby controlling the roll-off amount of the edge region of the wafer in accordance with the target profile.

[0092] Even though the embodiments of the present disclosure have been described in more detail with reference to the accompanying drawings, the present disclosure is not necessarily limited to these embodiments, and may be variously modified and implemented without departing from the technical spirit of the present disclosure. Therefore, the embodiments disclosed herein are not intended to limit the technical spirit of the present disclosure, but to describe the technical spirit, and the scope of the technical spirit of the present disclosure is not limited by these embodiments. Accordingly, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present disclosure should be construed according to the scope of the claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present disclosure.