SEO, Sung Bum (114-501, Jugong Apt. 778-1Busan-dong, Osan-si, Gyeonggi-do 447-717, KR)
YOON, Jung Woo (28-706, Miseong Apt.Apgujeong-dong, Gangnam-gu, Seoul 135-785, KR)
SEO, Sung Bum (114-501, Jugong Apt. 778-1Busan-dong, Osan-si, Gyeonggi-do 447-717, KR)
Claims
[1] A drive mechanism of a chemical mechanical polishing apparatus for rotating a rotating body installed on a polishing pad, and revolving and translating a polishing head, eccentrically installed on a lower surface of the rotating body to attach a wafer, on the polishing pad, the drive mechanism comprising: a non-rotating hollow center shaft vertically passing through the center of the rotating body to rotate the rotating body; a drive member for rotating the rotating body about the non-rotating hollow center shaft; a supply line for supplying a working fluid to the polishing head through the non-rotating hollow center shaft; and a power transmission member installed in the rotating body to translate the polishing head revolving on the polishing pad when the rotating body rotates, without any phase change. [2] The drive mechanism according to claim 1, wherein the power transmission member comprises: a stationary gear engaged with the non-rotating hollow center shaft; a polishing head rotating shaft in eccentric relation with the non-rotating hollow center shaft, rotatably engaged with the rotating body, and axially engaged with the polishing head; a driven gear engaged with the polishing head rotating shaft; an idle shaft in eccentric relation with the non-rotating hollow center shaft and rotatably engaged with the rotating body; and idle gears engaged with the idle shaft and meshed with the stationary gear and the driven gear. [3] The drive mechanism according to claim 2, wherein the stationary gear, the idle gears, and the driven gear are meshed with one another by a gear ratio of 1 : 1 : 1 to translate the polishing head without any phase change. [4] The drive mechanism according to claim 3, wherein the idle gears comprise: a first idle gear engaged with an upper end of the idle shaft and meshed with the stationary gear; and a second idle gear engaged with a lower end of the idle shaft and meshed with the driven gear. [5] The drive mechanism according to any one of claims 1 to 4, further comprising an electric line passing through the non-rotating hollow center shaft and connected to the polishing head. [6] The drive mechanism according to any one of claims 1 to 4, wherein the non- rotating hollow center shaft, through which the supply line is inserted, further comprises a tube guide installed adjacent to the supply line. |
Description
DRIVE MECHANISM OF A CHEMICAL MECHANICAL
POLISHING APPARATUS
Technical Field
[1] The present invention relates to a drive mechanism of a chemical mechanical polishing apparatus, and more particularly, to a drive mechanism of a chemical mechanical polishing apparatus capable of revolving and translating a polishing head on a polishing pad, and simultaneously supplying a working fluid for vacuum-sucking a wafer and pressing the wafer against the polishing pad. Background Art
[2] Generally, a semiconductor device is manufactured by performing various processes such as deposition, photolithography, etching, and ion implantation on a silicon wafer.
[3] For example, various process layers are formed on the silicon wafer during a manufacturing process. A portion of the process layer may be selectively removed and patterned, an additional process layer may be deposited on the previously formed process layer, and these processes may be repeated.
[4] Such a process layer may be an insulating layer, a gate oxide layer, a conductive layer, a metal layer, or a glass layer.
[5] In specific processes, an uppermost layer of the process layers previously formed on the wafer may be planarized in order to deposit the following process layer.
[6] Therefore, the silicon wafer is subjected to a polishing process for planarizing the previously formed process layer in order to stably perform the following process.
[7] That is, the wafer polishing process is a process for planarizing a surface of the wafer. For example, there is a chemical mechanical polishing (CMP) method of applying chemical slurry on a polishing head in friction contact with a wafer surface, and rubbing the wafer and the polishing pad in a state that the wafer surface to be polished is pressed against the polishing pad to planarize the wafer surface.
[8] FIG. 1 is a schematic view of a conventional chemical mechanical polishing apparatus.
[9] Referring to FIG. 1, the conventional chemical mechanical polishing apparatus includes a polishing pad 11 in surface contact with a water surface to be polished, and on which slurry is applied to perform a chemical mechanical polishing process, a platen 10 on which the polishing pad 11 is mounted, a polishing head 20 for fixing a wafer to be in friction contact with the polishing pad 11, a rotating body 30 for rotating the polishing head 20 on the polishing pad 11 in a pressed manner, and a loading unit
40 for loading a wafer to be treated on the polishing head 20 or unloading the polished wafer from the polishing head 20.
[10] In the loading unit 40, a wafer is loaded and supported on a loading plate 42 installed at an uppermost part of a loading cup 41. An arm 44 connected to the loading cup 41 is pivoted and raised/lowered to the polishing head 20 about a rotary shaft 43 such that the loading plate 42 and the polishing head 20 cooperates to attach or detach the wafer.
[11] The conventional chemical mechanical polishing apparatus may perform various wafer polishing methods. That is, the platen 10 on which the polishing pad 11 is mounted, the polishing head 20 to which a wafer is attached, and the rotating body 30 at which the polishing head 20 is installed relatively move in various manners to perform various polishing methods.
[12] For example, a conventional wafer polishing method is disclosed in Korean Patent
Registration No. 443330.
[13] In the above conventional art, a wafer and a polishing pad rotate at the same angular velocity such that the wafer is uniformly polished all over the surface. As a result, the wafer translates on the polishing pad about the center of the polishing pad by a predetermined radius.
[14] FIGS. 2 and 3 are schematic views illustrating a conventional wafer polishing method.
[15] Referring to FIGS. 2 and 3, in the conventional wafer polishing method, the wafer and the polishing pad have the same relative velocity at every point on the wafer to uniformly polish the wafer.
[16] As shown in FIG. 2,
W H is an angular velocity of the wafer, cδ ~ p is an angular velocity of the polishing pad,
is a position vector from a rotational center to a point P of the wafer,
T P is a position vector from a rotational center to a point P of the polishing pad, and
Tec is a position vector between the rotational center of the polishing pad and the rotational center of the wafer.
[17] Therefore, when the angular velocity of the wafer is equal to the angular velocity of the polishing pad (
), a relative velocity between the wafer and the polishing pad is varied depending on the angular velocity and a distance between the rotational centers, regardless of a position and a direction on the wafer. That is, a relative velocity V pi pad of the wafer to the polishing pad at the point P on the wafer can be expressed as the following formula. [18] [Formula]
V 1 plpad
ω ~ P X
[19] As described above, when the angular velocity of the wafer is equal to the angular velocity of the polishing pad, the relative velocity between the wafer and the polishing pad is the same at every point on the wafer, thereby uniformly polishing the wafer. [20] In FIG. 3, (a) to (c) illustrate a relative motion between a wafer and a polishing pad when the wafer and the polishing pad are relatively rotated. [21] That is, as shown in (a) to (c) of FIG. 3, the relative motion between the wafer and the polishing pad is the same as an orbital motion of a radius r performed by the wafer on the fixed polishing pad without rotating. [22] In FIG. 3, (a) sequentially illustrates states of the wafer and the polishing pad rotated to 0, 45, 90, 180, and 270 degrees, respectively. In this process, a small circle represents the water, and a large circle represents the polishing pad. Dots represent relative positions between the wafer and the polishing pad. [23] In FIG. 3, (b) re-illustrates (a) of FIG. 3 after fixing the polishing pad.
[24] As shown in (c) of FIG. 3, all points on the wafer draw a circle having a radius rcc on the polishing pad. [25] Meanwhile, the polishing head of the conventional chemical mechanical polishing apparatus generally attaches a wafer using a vacuum method. [26] As described above, in order to attach the wafer to the polishing head using a vacuum method and press the wafer attached to the polishing head against the polishing pad, a fluid supply line should be connected to the polishing head to supply a working fluid thereto.
[27] In addition, Korean Patent Registration Nos. 490266 and 530742, filed by the applicant, disclose a conventional chemical mechanical polishing apparatus providing a rotational driving force to the polishing head to be relatively rotated on the polishing pad, and supplying a working fluid to vacuum-suck and press the wafer.
[28] According to the conventional chemical mechanical polishing apparatus, a rotary union is essentially used as a means for smoothly supplying a working fluid between a rotating component and a stationary component.
[29] The rotary union is disclosed in detail in Korean Patent Publication No.
2005-581626, filed by the applicant.
[30] The rotary union has several inherent limitations as follows. For example, since a sealing member is worn away by physical friction when using for a long time to decrease its sealing performance, a separate cooling means should be required to reduce friction heat generated by the physical friction. Also, its components should be very precisely machined to prevent leakage of a working fluid. In addition, since there is a need to simultaneously perform power transmission and working fluid supply, its structure must be complicated, and its maintenance takes much time and cost due to the complicated structure.
[31] As described above, the conventional chemical mechanical polishing apparatus requires equalizing the relative velocity between the wafer and the polishing pad at every point on the wafer to uniformly polish the wafer, and smoothly supplying the working fluid to the polishing head relatively moved to the polishing pad according to the polishing method.
[32] Therefore, the chemical mechanical polishing apparatus should have a drive mechanism satisfying the above requirements as well as a constitution simpler than the rotary union.
[33] Meanwhile, a sensor for detecting a state of the wafer may be installed at the polishing head of the conventional chemical mechanical polishing apparatus.
[34] However, in the conventional chemical mechanical polishing apparatus, since the polishing head is relatively rotated with respect to a rotating body, it is impossible to directly connect an electric line for transmitting a signal to the sensor to the polishing head.
[35] Therefore, the conventional chemical mechanical polishing apparatus includes a slip ring installed at the polishing head to transmit a signal between rotating bodies. However, the signal transmission through the slip ring causes noise to be amplified, thereby making it difficult to transmit a fine signal. Disclosure of Invention Technical Problem
[36] In order to solve the above problems, the present invention provides a drive mechanism of a chemical mechanical polishing apparatus capable of smoothly supplying a working fluid for attaching and pressing a wafer to a polishing head, without a rotary union.
[37] The present invention also provides a drive mechanism of a chemical mechanical polishing apparatus capable of smoothly transmitting an electrical signal to a polishing head, without a slip ring. Technical Solution
[38] One aspect of the present invention provides a drive mechanism of a chemical mechanical polishing apparatus for rotating a rotating body installed on a polishing pad, and revolving and translating a polishing head, eccentrically installed on a lower surface of the rotating body to attach a wafer, on the polishing pad, the drive mechanism comprising: a non-rotating hollow center shaft vertically passing through the center of the rotating body to rotate the rotating body; a drive member for rotating the rotating body about the non-rotating hollow center shaft; a supply line for supplying a working fluid to the polishing head through the non-rotating hollow center shaft; and a power transmission member installed in the rotating body to translate the polishing head revolving on the polishing pad when the rotating body rotates, without any phase change.
[39] The power transmission member may comprise: a stationary gear engaged with the non-rotating hollow center shaft; a polishing head rotating shaft in eccentric relation with the non-rotating hollow center shaft, rotatably engaged with the rotating body, and axially engaged with the polishing head; a driven gear engaged with the polishing head rotating shaft; an idle shaft in eccentric relation with the non-rotating hollow center shaft and rotatably engaged with the rotating body; and idle gears engaged with the idle shaft and meshed with the stationary gear and the driven gear.
Advantageous Effects
[40] As described above, since a working fluid supply line is directly connected to a polishing head, it is possible to improve sealing performance to almost perfectly prevent leakage of a working fluid and pressure drop as well as precisely control the pressure of the working fluid. [41] In addition, since the polishing head revolves and translates, it is possible to prevent twist of the supply line directly connected to the polishing head and improve wafer polishing performance. [42] Further, since it is possible to omit a rotary union applied to the conventional art, it is possible to remarkably simplify and miniaturize the apparatus as well as reduce time and cost consumed for maintenance.
[43] Furthermore, since a plurality of supply lines can be connected to the polishing head, it is possible to apply a plurality of difference pressures at each part of the polishing head, to which a wafer is attached, thereby improving wafer attachment performance as well as locally adjusting a polishing amount of the wafer. [44] In addition, since an electric line for transmitting an electrical signal is directly connected to the polishing head, without a slip ring applied to the conventional art, it is possible to smoothly transmit the electrical signal to the polishing head, thereby improving wafer control performance of the polishing head. [45] Further, a single drive source performs rotation of the rotating body, revolution of the polishing head, and proper position control of the polishing head, thereby simplifying and miniaturizing the structure, and reducing manufacturing cost of the apparatus.
Brief Description of the Drawings [46] FIG. 1 is a schematic view of a conventional chemical mechanical polishing apparatus; [47] FIGS. 2 and 3 are schematic views illustrating a conventional wafer polishing method; [48] FIG. 4 is a cross-sectional view of a drive mechanism of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention; [49] FIG. 5 is a partially cut-away perspective view of an inner part of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention; [50] FIG. 6 illustrates the operating state of a polishing head on a polishing pad by a drive mechanism of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention; and [51] FIG. 7 illustrates the operating state of a power transmission member corresponding to the operating state of the polishing head shown in FIG. 6.
Mode for the Invention [52] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings, throughout which like reference numerals refer to like elements. [53] FIG. 4 is a cross-sectional view of a drive mechanism of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention, and FIG. 5 is a partially cut-away perspective view of an inner part of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention.
[54] Referring to FIGS. 4 and 5, a drive mechanism of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention includes: a non-rotating hollow center shaft 100 vertically passing through the center of a rotating body 500 such that the rotating body 500 can rotate; a drive member 200 for rotating the rotating body 500 about the non-rotating hollow center shaft 100; a supply line 300 for supplying a working fluid for sucking a wafer to a polishing head 800 through the non-rotating hollow center shaft 100; and a power transmission member 400 installed in an inner space 501 of the rotating body 500 to translate the polishing head 800 revolving on a polishing pad 910 when the rotating body 500 rotates, without any phase change.
[55] The rotating body 500 is installed over a platen 900, on which the polishing pad 910 is mounted, to rotate over the polishing pad 910.
[56] The rotating body 500 is referred to as a spindle, and a non-rotating spindle housing
600 is installed around the spindle.
[57] Specifically, a bearing 510 is installed between the rotating body 500 and the spindle housing 600 to rotatably support the rotating body 500.
[58] The non-rotating hollow center shaft 100 functions as a rotational center axis of the rotating body 500.
[59] Specifically, a bearing 120 is installed between the rotating body 500 and the non- rotating hollow center shaft 100 to rotatably support the rotating body 500.
[60] The non-rotating hollow center shaft 100, through which a supply line 300 and an electric line 310 are inserted, is fixedly engaged with a stationary bracket 130.
[61] For example, the non-rotating hollow center shaft 100, through which the supply line 300 and the electric line 310 are inserted, may further include a tube guide 110 installed adjacent to the supply line 300 and the electric line 310.
[62] The tube guide 110 is advantageous to minimize movement of the supply line 300 and the electric line 310 in the non-rotating hollow center shaft 100.
[63] For example, the rotating body 500 receives a rotational drive force from a drive member 200 installed at its one side.
[64] While the drive member 200 may be one of various conventional devices for transmitting a rotational drive force, a belt-type rotational drive force transmission device is described herein as an example.
[65] The drive member 200 includes a geared motor 240 installed at one side of the rotating body 500, a drive pulley 210 engaged with a drive shaft (not shown) of the geared motor 240, and a driven pulley 230 connected to the drive pulley 210 by a belt and engaged with an upper part of the rotating body 500.
[66] Therefore, the rotational drive force generated from the geared motor 240 is transmitted to the rotating body 500 through the drive pulley 210, a drive belt 220 and
the driven pulley 230.
[67] As a result, the rotating body 500 is supported by the spindle housing 600 and the non-rotating hollow center shaft 100 and rotated by the drive member 200.
[68] In addition, the polishing head 800 for attaching a wafer is installed at a bottom surface of the rotating body 500.
[69] The rotating body 500 may further include a conditioning head (not shown) installed at a bottom surface thereof for conditioning a surface of the polishing pad 910.
[70] The polishing head 800 attaches a wafer, and revolves on the polishing pad 910 by rotation of the rotating body 500 to press the wafer against the polishing pad 910, thereby polishing the wafer.
[71] The polishing head 800 should receive a working fluid for attaching and pressing the wafer. While the conventional polishing head receives the working fluid through a rotary union, the polishing head 800 of the present embodiment is directly connected to the supply line 300 for conveying the working fluid.
[72] That is, the working fluid is supplied to the polishing head 800 through the supply line 300 to attach a wafer using a vacuum method and press the wafer against the polishing pad 910.
[73] The polishing head 800 attaches the wafer using the working fluid in vacuum when the wafer is loaded, presses the wafer against the polishing pad 910 using the working fluid supplied through the supply line 300, and prevents separation of the wafer from the polishing pad 910 during a polishing process using a retainer ring (not shown) installed at a lower surface thereof.
[74] When the polishing head 800 presses the wafer against the polishing pad 910, different pressures can be applied from a center to an edge of the wafer to locally adjust a polishing amount of the wafer.
[75] Generally, the polishing head 800 includes a membrane (not shown) installed at its lower surface to be in surface contact with the wafer, and a plurality of compression chambers (not shown) radially installed in the polishing head 800 to be in communication with the supply line 300 to transmit the pressure to the membrane, thereby locally adjusting a polishing amount of the wafer.
[76] The supply line 300 is inserted through a through-hole 101 of a tube guide 110 installed in the non-rotating hollow center shaft 100 and directly connected to a fluid and electrical signal connection port 422 installed at an upper end of a polishing head rotating shaft 420 in the rotating body 500, thereby supplying the working fluid to the polishing head 800 or re-collecting the working fluid from the polishing head 800 such that the polishing head 800 attaches and detaches the wafer.
[77] As described above, since the supply line 300 is directly connected to the polishing
head 800, it is possible to perfectly prevent leakage of the working fluid and pressure drop, which may be generated from the conventional rotary union.
[78] For example, the supply line 300 may be a pressure regulation pneumatic line for vacuum sucking a wafer to the polishing head 800 or a fluid line for injecting water or chemical solution to the polishing head 800.
[79] In addition, the polishing head 800 should be electrically connected to the electric line 310. While the conventional polishing head is electrically connected to the electric line by a slip ring, the polishing head 800 of the present invention is directly connected to the electric line 310.
[80] Specifically, the electric line 310 is inserted through the through-hole 101 of the tube guide 110 installed in the non-rotating hollow center shaft 100 and directly connected to the fluid and electrical signal connection port 422 installed at the upper end of the polishing head rotating shaft 420 in the inner space 501 of the rotating body 500, thereby supplying power and transmitting signals to various sensors (not shown) installed at the polishing head 800.
[81] In the above constitution, the supply line 300 and the electric line 310 may be formed of a flexible material, and the polishing head 800 may be configured to revolve and translate by the power transmission member 400 to prevent twist of the supply line 300 and the electric line 310.
[82] As described above, the wafer can be uniformly polished when the polishing head
800 revolves and translates by rotation of the rotating body 500, without any phase change.
[83] For example, the platen 900 may be fixedly installed, or perform an auxiliary motion such as a separate oscillation motion to increase a polishing trajectory of the wafer.
[84] The power transmission member 400 converts rotation of the rotating body 500 into translation of the polishing head 800.
[85] The power transmission member 400 includes: a stationary gear 411 engaged with a lower end of the non-rotating hollow center shaft 100; the polishing head rotating shaft 420 in eccentric relation with the non-rotating hollow center shaft 100, rotatably engaged with the rotating body 500, and axially engaged with the polishing head 800 at its one end; a driven gear 421 engaged with the polishing head rotating shaft 420; an idle shaft 430 in eccentric relation with the non-rotating hollow center shaft 100 and rotatably engaged with the rotating body 500; and idle gears 431 and 432 engaged with the idle shaft 430 and meshed with the stationary gear 411 and the driven gear 421.
[86] The stationary gear 411 is fixedly engaged with the lower end of the non-rotating hollow center shaft 100.
[87] The polishing head rotating shaft 420 is rotatably engaged with the rotating body
500 by the bearing 520, and engaged with the polishing head 800 at its one end.
[88] The idle shaft 430 is installed in the inner space 501 of the rotating body 500, and rotatably engaged with top and bottom surfaces of the rotating body 500 by bearings 433 at its upper and lower ends.
[89] The idle gears 431 and 432 may be a first idle gear 431 meshed with the stationary gear 411, and a second idle gear 432 engaged with a lower end of the idle shaft 430 and meshed with the driven gear 421.
[90] As described above, since the idle gears 431 and 432 are installed at the upper and lower ends of the idle shaft 430, the polishing head 800 translates without any phase change to prevent twist between the working fluid supply line 300 and the electric line 310 for transmitting an electrical signal to the polishing head 800.
[91] In the above constitution, most preferably, the stationary gear 411, the idle gears
431 and 432, and the driven gear 421 are meshed with each other by a gear ratio of 1:1:1 such that the polishing head 800 translates on the polishing pad 910 without any phase change.
[92] Therefore, while the polishing head 800 revolves about the non-rotating hollow center shaft 100 by rotation of the rotating body 500, since the power transmission member 400 maintains the same position of the polishing head 800, it is possible to prevent twist between the supply line 300 and the electric line 310.
[93] FIG. 6 illustrates the operating state of a polishing head on a polishing pad by a drive mechanism of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention, and FIG. 7 illustrates the operating state of a power transmission member corresponding to the operating state of the polishing head shown in FIG. 6. Here, " — " shown on the polishing head 800 is an imaginary line for representing an absolute position of the polishing head 800, and "J." shown on the stationary gear 411 and the driven gear 421 are imaginary lines for representing absolute positions of the stationary gear 411 and the driven gear 421.
[94] Referring to FIGS. 6 and 7 together with FIGS. 4 and 5, the drive mechanism of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention converts rotation of the rotating body 500 into translation of the polishing head 800, thereby uniformly polishing the wafer and preventing twist of the supply line 300.
[95] Specifically, when the rotating body 500 rotates about the non-rotating hollow center shaft 100 by the drive member 200, the idle shaft 430, the polishing head rotating shaft 420, and the polishing head 800, which are eccentrically installed in the rotating body 500, rotate about the non-rotating hollow center shaft 100.
[96] At this time, since the stationary gear 411 fixedly engaged with the non-rotating hollow center shaft 100, the idle gears 431 and 432 engaged with the idle shaft 430,
and the driven gear 421 engaged with the polishing head rotating shaft 420 are meshed with one another, as shown in (a) to (d) of FIG. 7, the first idle gear 431 revolves along an outer surface of the stationary gear 411, and simultaneously, the second idle gear 432 and the driven gear 421 also revolve.
[97] In particular, the driven gear 421 revolves about the non-rotating hollow center shaft 100, and translates without any phase change as shown in FIG. 7.
[98] FIG. 6 illustrates revolution trajectories, in (a) to (d), of the polishing head 800 respectively corresponding to revolution trajectories of the driven gear 421 shown in (a) to (d) of FIG. 7.
[99] As shown in FIG. 6, the polishing head 800 rotating with the driven gear 421 revolves about the non-rotating hollow center shaft 100 and translates without any phase change.
[100] As described above, since the polishing head 800 translates without any phase change, it is possible to prevent twist of the supply line 300 directly connected to the polishing head 800 as well as uniformly polish the wafer attached to the polishing head 800.
[101] In addition, while the working fluid supply line 300 and the electric line 310 are inserted through the through-hole 101 of the tube guide 110 installed in the non- rotating hollow center shaft 100, various lines for performing various functions may be inserted through the through-hole 101 of the non-rotating hollow center shaft 100 to be connected to the polishing head 800 without any twist.
Industrial Applicability
[102] As can be seen from the foregoing, since a working fluid supply line is directly connected to a polishing head, it is possible to improve sealing performance to almost perfectly prevent leakage of a working fluid and pressure drop as well as precisely control the pressure of the working fluid.
[103] In addition, since the polishing head revolves and translates, it is possible to prevent twist of the supply line directly connected to the polishing head and improve wafer polishing performance.
[104] Further, since it is possible to omit a rotary union applied to the conventional art, it is possible to remarkably simplify and miniaturize the apparatus as well as reduce time and cost consumed for maintenance.
[105] Furthermore, since a plurality of supply lines can be connected to the polishing head, it is possible to apply a plurality of difference pressures at each part of the polishing head, to which a wafer is attached, thereby improving wafer attachment performance as well as locally adjusting a polishing amount of the wafer.
[106] In addition, since an electric line for transmitting an electrical signal is directly
connected to the polishing head, without a slip ring applied to the conventional art, it is possible to smoothly transmit the electrical signal to the polishing head, thereby improving wafer control performance of the polishing head.
[107] Further, a single drive source performs rotation of a rotating body, revolution of the polishing head, and proper position control of the polishing head, thereby simplifying and miniaturizing the structure, and reducing manufacturing cost of the apparatus.
[108] While few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes may be made to these embodiments without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.
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