PLATEN DRIVING SYSTEM OF CHEMICAL MECHANICAL POLISHING EQUIPMENT FOR WAFER

Technical Field

The present invention relates generally to a platen driving system of chemical mechanical polishing equipment for wafer, and more particularly to a platen driving system of chemical mechanical polishing equipment for wafer which is capable of oscillation movement and rotational movement in parallel so as to allow oscillation movement of polishing pad when polishing of wafer surface and rotational movement of polishing pad when washing of polishing pad as well.

Background Art

Generally semiconductor wafer manufacturing process consists of a plurality of processes including ion injection process, film deposition process, diffusion process, photo process, surface polishing process, washing process, and the like to form multi layers of semiconductor diode on surface of wafer made from silicon as its main raw material.

As a wafer surface polishing equipment in general for carrying out the surface polishing process out of above said processes, a chemical mechanical polishing (abbreviated as CMP hereinafter) equipment is widely used to perform high-precision planarizing operation by eliminating inter- layer unevenness on wafer surface through both mechanical polishing and chemical reaction with polishing slurry.

This kind of prior-art chemical mechanical polishing equipment for wafer as illustrated in FIG. 1 has a configuration which is furnished with a platen 3 attached thereon by a polishing pad 2, and with a wafer rotating device 4 installed beyond said polishing pad 2 for rotating and/or revolving

the wafer 1 which is in contact with the polishing pad 2, wherein said wafer rotating device 4 has a configuration which is furnished with a carrier 5 to rotate the wafer 1 as held and attached thereto and with a spindle 6 to revolve said carrier 5. Therefore, in traditional type of wafer surface polishing equipment

100 as illustrated in FIG. 1 , said wafer 1 gets into contact with polishing pad

2 supported by said platen 3, and this wafer 1 on contacting with polishing pad rotates by virtue of said carrier 5 and revolves at the same time by said spindle 6, thereby surface of wafer 1 contacted with said polishing pad 2 can be polished.

This kind of traditional fixed-type platen 3 as illustrated in FIG. 1 is however installed fixedly against ground so that polishing pad 2 should not move while wafer 1 rotates and revolves by wafer rotating equipment 4. So if there occurs any uneven part at a portion of the polishing pad 2 by prominences or impurities adhered, scratches incurred by the prominences or impurities during wafer polishing process will concentrate on wafer 1 at a particular place of wafer surface so as to increase damage of the wafer 1. Such damaged portion happening repeatedly will result in 1 frequent production of bad-quality wafer. In order to solve those problems described above, an oscillation-type platen driving equipment 110 as illustrated in FIG. 2 was developed and suggested later as a prior art technology, wherein cam groove 7 is formed at lower plane of said platen 3. In addition, cam 8 can rotate eccentrically because it is in combination with a driving motor 9 on one hand and gets inserted in said cam groove 7 on the other hand, which enables said platen 3 to oscillate (vibrate) back-and-forth left-and-right by virtue of rotational movement of said cam 8.

In this kind of oscillation-type platen driving equipment 110 according to prior art however, when it is considered that rotational movement of said cam 7 should convert into oscillation movement of said platen 3, said platen

3 can not rotate by itself regrettably, but can only move and change its

position on a predetermined circular orbit. Moreover, said platen 3 can not rotate either when said polishing pad 2 is to be washed by use of washing slurry spray nozzle 12, which means said platen 3 cannot produce centrifugal force, thereby it is difficult to eliminate impurities from said polishing pad 2, so it takes longer time for washing.

In order to solve the problems accompanied by above oscillation-type platen driving equipment 110, a rotation-type platen driving equipment 120 according to a prior art was developed and suggested as illustrated in FIG. 3, wherein center of platen 3 is concentrically combined to rotational shaft 11 of driving motor 10; it is possible in washing process thereof to wash said polishing pad 2 with washing slurry spray nozzle 12 by use of centrifugal force produced at high-speed rotating of said platen. Therefore with this kind of platen driving equipment, elimination of impurities from said polishing pad

2 is easy to be done, so that washing time can be reduced. However in this configuration, because said wafer 1 makes rotational movement and revolution movement during the process of polishing of wafer 1 , said polishing pad 2 does not need to rotate overlapping; furthermore, said platen

3 can not make oscillation movement either in this configuration. Therefore, if any uneven part at a portion of the polishing pad 2 appears by prominences or impurities adhered, occurrences of scratches on wafer 1 by the prominences or impurities during wafer polishing process will concentrate at a particular place of wafer surface so as to increase damage of the wafer 1. Repeated happening of such damaged portion can cause frequent production of poor-quality wafer 1. By this kind of platen driving equipment, accordingly the problem accompanied by the prior art of fixed- type platen 3 as illustrated in FIG. 1 can not be solved.

Therefore, there was a great necessity for development of a technology where said platen 3 can perform oscillation movement when polishing of wafer and high-speed rotational movement when washing of polishing pad 2; nevertheless, it was very difficult to realize such a conception in a technical way.

DISCLOSURE OF THE INVENTION Technical Problem

The present invention was contrived to alleviate or solve above- mentioned problems and/or drawbacks. It is an object of the present invention therefore to provide a platen driving system of chemical mechanical polishing equipment for wafer, wherein the platen can perform selectively either oscillation movement when polishing of wafer or high- speed rotational movement when washing of polishing pad, which can thereby prevent from occurrence of bad-quality wafer, and increase at the same time efficiencies both in washing of polishing pad and in removal of impurities so as to reduce washing time remarkably.

Technical Solution

In order to achieve the object described as above, a platen driving system of chemical mechanical polishing equipment for wafer according to the present invention comprises: a moving plate furnished thereon with a polishing pad, the moving plate being installed in such a manner that said moving plate is capable of performing selectively either oscillation movement or rotational movement; a middle supporting plate installed concentrically under and spaced-apart from said moving plate; a driving shaft installed at center of said middle supporting plate in such a manner that said driving shaft is capable of moving up and down; a cam member inserted at upper side of said driving shaft, the cam member being installed in such a manner that said cam member should get combined by cam with said moving plate when said driving shaft is at up-position; a driving shaft lift means which can take up said driving shaft when polishing of wafer so that said cam member should get combined by cam with said moving plate and take down said

driving shaft when washing of polishing pad so that said driving shaft should get joined with said middle supporting plate; a driving shaft rotating means to rotate said driving shaft; an oscillation guide means installed between said moving plate and middle supporting plate to guide oscillation path for oscillation movement of said moving plate when said cam member is in combination by cam with said moving plate; and a rotation supporting means which is installed between said moving plate and middle supporting plate so that said moving plate should rotate according to rotation of said driving shaft when said driving shaft is in combination with said middle supporting plate. It is preferable in above description that said cam member should correspond to a cam groove member which is formed at lower plane of said moving plate, and be installed eccentrically to rotational center of said driving shaft so that the moving plate should be able to do oscillation(vibration) movement; said driving shaft should be formed at its periphery with a plurality of protruding parts; and said middle supporting plate should be formed at its center with a groove member to be joined with said protruding parts so that said protruding parts of said driving shaft should get inserted into said groove of said middle supporting plate when said driving shaft is at down-position. In addition, said driving shaft lift means might comprise: a lift motor; a ball screw to be rotated by driving of said lift motor; a lift plate inserted at periphery of said ball screw to move up and down as said ball screw rotates; and a connection plate located at upper side of said lift plate for transferring up-and-down motion of said lift plate to the driving shaft. Moreover, it is preferable that said driving shaft rotating means should comprise: an oscillation/rotation motor installed at said lift plate; a driving pulley to be driven by driving of said oscillation/rotation motor; a driven pulley to be driven by driving of said driving pulley; and a connection plate which is to be rotated by driving of said driven pulley in order to rotate the driving shaft located at upper side.

In addition, it is preferable that said oscillation guide means should comprise a dual-axis oscillation guide member consisting of X-axis guide which is combined to said moving plate so that oscillation of said moving plate should follow circular path, and Y-axis guide which is combined to said X-axis guide and fixed at said middle supporting plate.

Moreover, it is preferable that said rotation supporting means should comprise: a centering housing fixedly combined at upper side of said driving shaft; a plurality of rollers in contact with periphery of said centering housing; and a centering guide bracket of which one side is combined with said roller and the other side is fixedly combined with lower part of said moving plate.

Moreover, one side of said middle supporting plate might be further furnished with a carriage to guide up-and-down motion of said middle supporting plate, and with a stopper to limit the lowest position of said carriage.

Advantageous Effect

According to the platen driving system of chemical mechanical polishing equipment for wafer of the present invention, the platen can perform either oscillation movement when polishing of wafer or rotational movement when washing of polishing pad, thereby it is possible to prevent from occurrence of bad-quality wafer, to raise at the same time efficiencies both in washing of polishing pad and in removal of impurities, and to reduce washing time remarkably as well.

Brief Description of the Drawings

FIG. 1 is perspective view illustrating chemical mechanical polishing equipment for wafer (fixed-platen type) according to a traditional embodiment;

FIG. 2 is side sectional view illustrating chemical mechanical polishing equipment for wafer (oscillating-platen type) according to another traditional embodiment;

FIG. 3 is side sectional view illustrating chemical mechanical polishing equipment for wafer (rotating-platen type) according to another traditional embodiment;

FIG. 4 is side sectional view illustrating a platen driving system of chemical mechanical polishing equipment for wafer according to present invention; FIG. 5 is top view showing the status when the moving plate in FIG. 4 has been removed;

FIG. 6 is an explanatory drawing to show the driving shaft lift means of a platen driving system of chemical mechanical polishing equipment for wafer according to present invention; FIG. 7 is perspective view of the driving shaft of a platen driving system of chemical mechanical polishing equipment for wafer according to present invention;

FIG. 8 is side sectional view showing up-position of driving shaft (oscillating-platen mode) in the platen driving system of chemical mechanical polishing equipment for wafer of FIG. 4;

FIG. 9 is side sectional view showing middle-position of driving shaft (standby-platen mode) in the platen driving system of chemical mechanical polishing equipment for wafer of FIG. 4;

FIG. 10 is side sectional view showing down-position of driving shaft (rotating-platen mode) in the platen driving system of chemical mechanical polishing equipment for wafer of FIG. 4; and

FIG. 11 is perspective view showing the status when the moving plate of FIG. 4 has been removed.

Best Mode for Carrying Out the Invention

Hereinafter, a platen driving system of chemical mechanical polishing equipment for wafer according to a preferred embodiment of the present invention will be described in detail with reference to appended drawings.

The platen driving system of chemical mechanical polishing equipment for wafer according to a preferred embodiment of the present invention comprises, as illustrated in FIG. 4, a moving plate 20, a middle supporting plate 22, a driving shaft 25, a cam member 24, a driving shaft lift means 30, a driving shaft rotating means 40, an oscillation guide means 50, and a rotation supporting means 60.

The moving plate 20 mentioned above is furnished thereon with a polishing pad 21 , and installed in such a manner that its oscillation movement and rotational movement each are possible; as illustrated in FIG. 8, it does oscillation movement when polishing of wafer so that scratches of wafer should be prevented from gathering at one place; as illustrated in FIG. 10, it does rotational movement when washing of polishing pad so that impurities should be removed by use of centrifugal force. The term of "oscillation" used in this specification means a circular orbital movement without any phase change.

Said middle supporting plate 22 is installed concentrically under and spaced-apart from said moving plate 20, and is formed at its center with a groove member 22a whereto the protruding parts 25a of driving shaft 25 (to be described later in this specification) get inserted. Said driving shaft 25 is installed at center of said middle supporting plate 22 in such a manner that said driving shaft 25 can move up and down. Referring to FIGS. 5 and 7, said driving shaft 25 is formed at its periphery with a plurality of protruding parts 25a; referring to FIG. 10, these protruding parts 25a get inserted to and combined with the groove member 22a of said middle supporting plate 22 when said driving shaft 25 is at down-position.

Said cam member 24, as illustrated in FIG. 4, is inserted at upper side of said driving shaft 25; and installed eccentrically to the rotational center of said driving shaft 25 so that oscillation (vibration) movement of said moving plate 20 is possible. Said cam member 24 will get inserted in and combined by cam with the cam groove member 28 formed at lower plane of said moving plate 20 when said driving shaft 25 is at up-position.

Said driving shaft lift means 30, which comprises a lift motor 31, a ball screw 32, a lift plate 33 and a connection plate 45, can take up said driving shaft 25 when polishing of wafer so that said cam member 24 should get combined by cam with said moving plate 20, and take down said driving shaft 25 when washing of polishing pad so that said driving shaft 25 should get joined with said middle supporting plate 22.

Said ball screw 32 is rotated by driving of the lift motor 31 installed at base 54. As said ball screw 32 rotates, the nut 34 combined by screw at periphery of said ball screw 32 moves up and down. Referring to FIG. 6, said ball screw 32 can transfer power from said lift motor 31 through coupling 37 and speed reducer 36.

Said lift plate 33 is inserted at periphery of said ball screw 32, and combined fixedly with the nut 34 that moves up and down when said ball screw 32 rotates, so said lift plate 33 moves up and down together with the motion of said nut 34.

Said lift plate 33 may further achieve a stable up-and-down motion when it is allowed to move up and down along a guide rod 39 that is fixedly installed at base 54. Said connection plate 45 is located at upper side of said lift plate 33 and transfers up-and-down motion of said lift plate 33 to driving shaft 25.

Moreover, said driving shaft rotation means 40, which is installed at said lift plate 33 for rotating said driving shaft 25, comprises an oscillation/rotation motor 41 , a driving pulley 42, a driven pulley 44, and a connection plate 45.

Said oscillation/rotation motor 41 , which is installed at said lift plate

33, generates either oscillating force for said moving plate 20 when said driving shaft 25 moves up and gets connected with said moving plate 20, or rotating force for said moving plate 20 when said driving plate 25 moves down and gets connected with said middle supporting plate 22.

Said driving pulley 42 is driven by driving of said oscillation/rotation motor 41 ; a speed reducer 46 may be installed between said driving pulley 42 and oscillation/rotation motor 41.

In addition, said driven pulley 44 as inserted at periphery of said screw 32 receives rotating force from said driving pulley 42 through a belt 43 and transfers it to the connection plate 45 located at upper side.

Said connection plate 45 is rotated by driving of said driven pulley 44 so as to rotate the driving shaft 25 located at upper side.

Said oscillation guide means 50 is installed between said moving plate 20 and middle supporting plate 22 and functions as a guide means of oscillating path for oscillation movement of said moving plate 20 when said cam member 24 is in combination by cam with said moving plate 20.

Referring to FIGS. 5 and 11 , said oscillation guide means 50 comprises a dual-axis oscillation guide member consisting of X-axis guide 51 which is connected to said moving plate 20 and Y-axis guide 52 which is connected to said X-axis guide 51 and fixed at said middle supporting plate 22, in order that oscillation of said moving plate 20 should be made along circular path.

By virtue of said dual-axis oscillation guide member, said moving plate 20 is therefore capable of performing oscillation movement with circular orbit. Said moving plate 20 is in connection with said middle supporting plate 22 via said dual-axis oscillation guide member in-between.

Said rotation supporting means 60 is installed between said moving plate 20 and middle supporting plate 22, functions as a means to make said moving plate 20 rotate along with rotation of said driving shaft 25 when said driving shaft 25 is in combination with said middle supporting plate 22, and

comprises, referring to FIGS. 5 and 11 , a centering housing 61 , a plurality of rollers 62, and a centering guide bracket 63.

Referring to FIGS. 4 and 11 , Said centering housing 61 is fixedly combined at upper side of said driving shaft 25, and rotates together with said driving shaft 25 and middle supporting plate 22 when the protruding parts 25a of said driving shaft 25 rotate as they get inserted in the groove member 22a of said middle supporting plate 22.

Said plurality of rollers 62 are in contact with periphery of said centering housing 61. Said centering guide bracket 63, because its one side is combined with said roller 62 and the other side is fixedly combined to lower part of said moving plate 20, can support rotation of moving plate 20 together with said middle supporting plate 22 when said middle supporting plate 22 rotates according to rotation of said driving shaft 25. Now, said middle supporting plate 22 may be further furnished at its one side with a carriage 70 to guide up-and-down movement of said middle supporting plate 22. Referring to FIGS. 4 and 6, a guide 72 is attached at one side of said carriage 70; and the guide 72 moves up and down in accordance with a guide rail 71. In addition, said carriage 70 is furnished further with a stopper 75 to limit the possible lowest position for moving down. Referring to FIG. 9, when said carriage 70 contacts with the stopper 74, it cannot move down further, and accordingly the middle supporting plate 22 fixedly combined with carriage 70 also stops and cannot move down further. If the driving shaft 25 at such state moves down further, referring to FIG. 10, the protruding parts 25a of driving shaft 25 get inserted in groove member 22a of middle supporting plate 22, so said driving shaft 25 gets combined with middle supporting plate 22.

Moreover, said middle supporting plate 22 may further be furnished at lower part thereof with a rotation preventing pin 23 in order to prevent said middle supporting plate 22 from rotation when the combination between said

driving shaft 25 and said middle supporting plate 22 gets disconnected. Said rotation preventing pin 23 when inserted into middle supporting plate 22 can prevent rotation of said middle supporting plate 22 notwithstanding rotation of said driving shaft 25. Hereinafter, operating process of the platen driving system of chemical mechanical polishing equipment for wafer according to the present invention will be described in detail with reference to the appended drawings. At oscillation mode when polishing of wafer: Referring to FIG. 8, when the lift motor 31 of said driving shaft lift means 30 rotates, said lift plate 33 moves upwards in accordance with said guide rod 39 by rotation of ball screw 32; said driving shaft 25 moves up along with said lift plate 33; and then, the cam member 24 attached at end of said driving shaft 25 gets inserted into cam groove member 28 of said moving plate 20 so as to become position of cam-combination. At next step, when the oscillation/rotation motor 41 of said driving shaft rotation means 40 rotates, said driving pulley 42 rotates and transfers rotating force to said driving shaft 25 through said driven pulley 44 and connection plate 45, and when said driving shaft 25 rotates, said cam member 24 rotates eccentrically around said moving plate 20. At this time, the protruding parts 25a formed at lower part of said driving part 25 gets disconnected from jointing with said middle supporting plate 22 due to rising-up of said driving shaft 25, so as to be made fixed because of failure in transfer of rotating force from said driving shaft 25. Thus, thanks to said middle supporting plate 22 made fixed, the dual-axis oscillation guide member consisting of X-axis guide 51 and Y-axis guide 52 can introduce a circular orbit movement without any phase change as X-axis movement and Y-axis movement of said moving plate 20.

Then, referring to FIG. 9, at stand-by mode in preparation of washing of said polishing pad 21 after completion of wafer polishing: When the lift motor 31 of said driving shaft lift means 30 rotates reversely by first-order, said lift plate 33 moves down firstly in accordance with said guide rod 39 by

virtue of the reverse rotation of ball screw 32; the driving shaft 25 also moves down together with moving-down of said lift plate 33; and the moving plate 20 that is in cam-combination with said driving shaft 25 moves down by weight as said driving shaft 25 moves down. At this step, however, while the middle supporting plate 22 combined to lower part of said moving plate 20 moves down in accordance with moving-down of the moving plate 20, said middle supporting plate 22 cannot move down further than the position where the carriage 70 combined at lower part of said middle supporting plate 22 hits the stopper 75, but keeps at the same position .

Then, at rotational mode when washing of polishing pad: Referring to FIG. 10, when the lift motor 31 of said driving shaft lift means 30 continues second-order reverse rotation, the driving shaft 25 continues to move down while said middle supporting plate 22 remains at the same state as before. Thus, the cam member 24 attached at end of said driving shaft 25 gets to escape completely from the lower part of moving plate 20; and at the same time, a plurality of protruding parts 25a formed at periphery of said driving shaft 25 gets inserted to the groove member 22a of said middle supporting plate 22, so that said driving shaft 25 and said middle supporting plate 22 can get combined each other.

Thereafter, when the oscillation/rotation motor 41 of said driving shaft rotation means 40 rotates, the rotational force of said oscillation/rotation motor 41 gets transferred to said driving shaft 25 via driving pulley 42, driven pulley 44, and connection plate 45. At this time, when said driving shaft 25 rotates, the centering housing

61 which is combined with the upper side of said driving shaft 25 also rotates together with said middle supporting plate 22. Because a plurality of rollers

62 engages with the periphery of said centering housing 61 , said centering housing 61 cannot escape outwards but rotates among the plurality of rollers 62. Now, because said rollers 62 are in fixed combination with centering guide bracket 63, and because said centering guide bracket 63 is in fixed

combination with lower part of moving plate 20, rotation of said driving shaft

25 can be transferred to moving plate 20 through said centering housing 61. In this way, as said driving shaft 25 rotates, the moving plate 20 also rotates, which can generate centrifugal force; and at this state, spraying of washing water on polishing pad 21 can remove impurities by use of centrifugal force.

In addition, there might be further installed with support stand 80 formed with waterway 81 , or bellows cover 82 and the like that is capable of extension and shrinkage, so that water can be easily discharged on oscillation movement or rotational movement of said moving plate 20

The present invention is not limited within the preferred embodiments that have been described hereinbefore, and it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. For example, although the preferred embodiments of the present invention seem to limit the forms of constituents of the present invention within the appended drawings, it is possible to those who have common knowledge in the art that various modifications, variations and changes can be made without departing from the technical concepts of the invention in the forms, designs, materials, sizes, and/or numbers for describing constituents of the present invention.

Therefore, the scope of patented right to be claimed according to the present invention will not be determined within the scope of detailed description but by the claims to be described hereinafter and by technical concepts thereof.

Industrial Applicability

As it has been described hereinbefore, the platen driving system of chemical mechanical polishing equipment for wafer of the present invention

can perform either oscillation movement of platen when polishing of wafer or rotational movement of platen when washing of polishing pad, thereby it has advantageous effects of preventing from occurrences of bad-quality wafer, of enhancing efficiencies both in washing of polishing pad and in removal of impurities, and of reducing washing time remarkably.