US20080274673A1

US20080274673A1 - Wafer polishing apparatus, wafer polishing system and wafer polishing method

Info

Publication number: US20080274673A1
Application number: US12/079,155
Authority: US
Inventors: Tadashi Adachi
Original assignee: Tokyo Seimitsu Co Ltd
Current assignee: Tokyo Seimitsu Co Ltd
Priority date: 2007-05-01
Filing date: 2008-03-25
Publication date: 2008-11-06
Also published as: JP2008277635A; TWI362698B; TW200845174A

Abstract

It is possible to execute a one-step polishing or a plural-step polishing at a high throughput, and it is possible to achieve a reduction of an occupied area on the basis of a compact structure of a whole apparatus. Two platens are respectively provided with a first wafer retention head and a second wafer retention head, and a wafer transfer apparatus on which a wafer is mounted is arranged between two platens. The two wafer retention heads are moved between two platens and the wafer transfer apparatus respectively by a first moving means and a second moving means. Further, a two-step polishing is executed by whirl moving two wafer retention heads from one platen to the other platen at 180 degree respectively by a whirl moving means supporting two moving means.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a wafer polishing apparatus, a wafer polishing system and a wafer polishing method, and more particularly to a wafer polishing apparatus, a wafer polishing system and a wafer polishing method executing a polishing work according to one step or two or more steps by using a plurality of platens.
2. Description of the Related Art
Conventionally, this kind of wafer polishing apparatus (CMP apparatus) 1 is provided with a rotationally drivable platen 2, a polishing pad 3 stuck to an upper surface of the platen 2, an upward and downward movable wafer retaining head 4 retaining a wafer, and a feed nozzle (not shown) feeding an abrasive agent to an upper surface of the polishing pad 3, as shown in FIG. 9, and the platen 2 is structured such as to be rotated via a rotating shaft 6 on the basis of a drive of a motor 5.
At a time of polishing the wafer, the wafer is polished by pressing the wafer to the upper surface of the polishing pad 3 at a predetermined pressure, and feeding the abrasive agent to the upper surface of the polishing pad 3 while rotating the polishing pad 3 and the wafer.
In the case of CMP processing a plurality of wafers, in the view of an improvement of a throughput, there is a method of simultaneously CMP processing a plurality of wafers by arranging a plurality of wafers on the same platen, however, since it is impossible to secure a uniform high work quality in all a plurality of wafers, there is employed a method of CMP processing one wafer by one platen.
Further, in the case of mounting the wafers one by one on one platen and polishing the wafer according to a one-step polishing, that is, in one step, or polishing according to a two-step polishing, that is, in two steps while changing a polishing condition (kind of the abrasive agent, a polishing pressure, a polishing speed and the like) in the middle, a waiting time is generated at a time of feeding the wafer to one platen or discharging the wafer from one platen. Accordingly, a throughput is lowered.
In order to improve the throughput, there have been conventionally proposed various polishing methods. For example, there is a structure obtained by combining one platen, and n sets of units (including a common transfer apparatus) provided with a positioning means retaining one wafer retention head so as to be capable of positioning to one transfer apparatus (for example, refer to patent documents 1 and 2). Further, there is a structure provided with n platens, and a positioning means retaining (n+1) wafer retention heads so as to be capable of positioning to one transfer apparatus (for example, refer to patent documents 3 and 4).
Further, there is a structure obtained by combing two platens, and two units provided with a positioning means retaining a wafer retention head so as to be capable of positioning to one transfer apparatus, and using one platen in common (for example, refer to patent documents 5 and 6). Further, there is a structure provided with two platens, and two positioning means retaining a wafer retention head so as to be capable of positioning to a transfer apparatus, and making the positioning means independently controllable with each other (for example, refer to patent document 7).
Patent Document 1: Japanese Unexamined Patent Publication No. 11-204468
Patent Document 2: Japanese Unexamined Patent Publication No. 10-202515
Patent Document 3: Japanese Unexamined Patent Publication No. 09-174420
Patent Document 4: Japanese Unexamined Patent Publication No. 2005-131772
Patent Document 5: Japanese Unexamined Patent Publication No. 2003-332282
Patent Document 6: Japanese Unexamined Patent Publication No. 2000-263433
Patent Document 7: Japanese Unexamined Patent Publication No. 2000-117628

SUMMARY OF THE INVENTION

In the prior art described in the patent document 1 or 2, since it is difficult to carry out a continuous polishing work in the case of executing the two-step polishing, a processing efficiency is lowered.
Further, in the prior art described in the patent document 3 or 4, the CMP process can be carried out continuously without rehandling the wafer in the case of executing the two-step polishing, however, the CMP process is carried out between a plurality of platens in the case of executing the one-step polishing. Accordingly, a productivity is lowered at a time for moving the wafer between a plurality of platens.
Further, in the prior art described in the patent document 5 or 6, since there exists the platen which is not used, in the case of executing the one-step polishing, a size of the apparatus becomes large. Further, in the prior art described in the patent document 7, the efficient polishing work can be achieved in both of the one-step polishing and the two-step polishing, however, it is necessary to arrange the platen and the transfer apparatus on a circumference, and a size of the apparatus becomes large for securing a rigidity of the positioning means.
In the prior art, there has been generally employed a method of sequentially executing a plural-step polishing on each of the platens by using different kinds of abrasive agents and providing a plurality of platens per kinds of the abrasive agents, or a method of providing a wafer retention head per a plurality of platens, however, each of them has an advantage and a disadvantage. It is difficult to achieve a high throughput in both of the one-step polishing and the plural-step polishing, the numbers of the platens and the wafer retention heads are increased, and there is a problem that a whole size of the apparatus is enlarged.
Accordingly, in the case of carrying out the one-step polishing by using one platen, or in the case of carrying out the plural-step polishing by sequentially using a plurality of platens, there is generated a technical problem to be solved for polishing the wafer at a high throughput and reducing an occupied space without enlarging a whole of the apparatus. An object of the present invention is to solve the problem.
The present invention is proposed for achieving the object mentioned above. According to the invention described in claim 1, there is provided a wafer polishing apparatus polishing a wafer by pressing the wafer retained by a wafer retention head to a polishing pad on a platen, comprising: a first platen and a second platen provided in parallel while having a gap from each other; a first wafer retention head and a second wafer retention head respectively installed above the first platen and the second platen and being movable up and down; a wafer transfer apparatus arranged between the first platen and the second platen and on which the wafer before being polished and the wafer after being polished are mounted; a first moving means moving and stopping the first wafer retention head to both positioning portions of the first platen and the wafer transfer apparatus; a second moving means moving and stopping the second wafer retention head to both positioning portions of the second platen and the wafer transfer apparatus; and a third moving means supporting the first moving means and the second moving means, and whirling around the wafer transfer apparatus so as to move and stop the first wafer retention head and the second wafer retention head respectively to the positioning portions of the second platen and the first platen, wherein the wafer polished by the first platen or the second platen is whirled and moved to the positioning portion of the second platen or the first platen so as to be polished.
According to this structure, in the case of the one-step polishing, the first platen and the second platen polish by setting their polishing conditions identical. First, the first wafer retention head is moved to the positioning portion of the wafer transfer apparatus by the first moving means so as to retain the wafer, and the polishing work is started by moving the wafer retention head to the positioning portion of the first platen. In slightly retard of this, after the second wafer is mounted to the wafer transfer apparatus, the wafer is retained by the second wafer retention head in the same manner as mentioned above, and is moved to the positioning portion of the second platen, and the polishing work is started.
As mentioned above, two wafers are sequentially and independently moved to the first platen and the second platen respectively so as to be polished, the polished wafers are sequentially moved to the wafer carry-out portion on the wafer transfer apparatus so as to be discharged, thereafter the third wafer and the fourth wafer carried in the wafer transfer apparatus are retained by the first wafer retention head and the second wafer retention head respectively, and the one-step polishing is repeated in the same procedure as mentioned above.
Further, in the case of the two-step polishing, the first platen and the second platen polish by differentiating the polishing conditions. First, the first wafer is mounted to a wafer carry-in position of the wafer transfer apparatus, the first wafer retention head is thereafter moved to the wafer carry-in position of the wafer transfer apparatus by the first moving means so as to retain the wafer, and the first wafer retention head is next moved to the polishing position of the first platen so as to start polishing.
On the other hand, the second wafer retention head is moved to the wafer feed portion on the wafer transfer apparatus by the second moving means so as to retain the second wafer. Further, after the end of the polishing of the first wafer, the first wafer retention head is whirled and moved to the polishing position of the second platen by the third moving means, and the second wafer is moved to the polishing position of the first platen by the second moving means so as to start polishing.
After the end of the polishing of the first wafer, the first wafer retention head is moved to the wafer transfer apparatus so as to discharge the first wafer, and thereafter retains the third wafer instead. Further, after the end of the polishing of the second wafer, the second wafer retention head is whirled and moved to the polishing position of the second platen by the third moving means so as to start polishing. Thereafter, the two-step polishing is sequentially carried out by the first platen and the second platen, by repeating the steps mentioned above.
According to the invention described in claim 2, there is provided a wafer polishing apparatus polishing a wafer by pressing the wafer retained by a wafer retention head to a polishing pad on a platen, comprising: a first platen and a second platen provided in parallel while having a gap from each other; a first wafer retention head and a second wafer retention head respectively installed above the first platen and the second platen and being movable up and down; a wafer transfer apparatus arranged between the first platen and the second platen and on which the wafer before being polished and the wafer after being polished are mounted; a first moving means moving and stopping the first wafer retention head to both positioning portions of the first platen and the wafer transfer apparatus; a second moving means moving and stopping the second wafer retention head to both positioning portions of the second platen and the wafer transfer apparatus; and a third moving means supporting the first moving means and the second moving means, and whirling around the wafer transfer apparatus so as to move and stop the first wafer retention head and the second wafer retention head respectively to the positioning portions of the second platen and the first platen, wherein the wafer polished by the first platen or the second platen is whirled and moved to the positioning portion of the second platen or the first platen so as to be polished, a partition wall for preventing a liquid from flying in all directions is provided between the first platen and the wafer transfer apparatus, and between the second platen and the wafer transfer apparatus, a passage through which the first wafer retention head and the second wafer retention head pass is formed in the partition wall, and the partition wall is provided in such a manner as to be capable of integrally whirling with the third moving means.
According to this structure, the same operation as claim 1 can be achieved. In addition, even if the first platen and the second platen are arranged close to each other, it is possible to prevent the abrasive agent or the like fed to one of two platens from flying in all directions toward the other platen during the polishing work because the partition wall is provided between each of the platens and the wafer transfer apparatus. Further, since the passage allowing the movement of each of the wafer retention heads is formed in the partition wall, and the partition wall is attached so as to be capable of integrally whirling with the third moving means, the wafer retention head is moved between two platens and the wafer transfer apparatus without being interfered with the partition wall.
According to the invention described in claim 3, there is provided a wafer polishing apparatus as described in claim 1 or 2, wherein the wafer transfer apparatus is provided with a wafer carry-in means carrying in the unpolished wafer, and a wafer carry-out means carrying out the polished wafer, and the wafer carry-out means and the wafer carry-in means are structured such as to be independently movable to a position corresponding to a center position of whirling of the third moving means.
According to this structure, the wafer carry-in means and the wafer carry-out means are moved to the position corresponding to the center position of whirling of the third moving means independently from each other in alternate shifts. Accordingly, the unpolished wafer is retained by the wafer retention head after being set to the wafer feed portion on the wafer transfer apparatus by the wafer carry-in means. Further, the polished wafer is carried out to the outer portion by the wafer carry-out means after being set to the wafer discharge portion on the wafer transfer apparatus by the wafer retention head.
According to the invention described in claim 4, there is provided a wafer polishing apparatus as described in claim 1, 2 or 3, wherein the third moving means is provided so as to be retractable from the center position of whirling, and ahead cleaning apparatus for cleaning the first wafer retention head and the second wafer retention head is installed at the center position of whirling.
According to this structure, the first wafer retention head or the second wafer retention head is cleaned by the head cleaning apparatus by retracting the third moving means to a predetermined position from the center position of whirling at a time of cleaning the first wafer retention head or the second wafer retention head.
According to the invention described in claim 5, there is provided a wafer polishing system provided with the wafer polishing apparatus as described in claim 1 or 2, wherein two or more the wafer polishing apparatuses are provided in parallel, and a transfer apparatus for transferring the wafer polished by one wafer polishing apparatus to the other wafer polishing apparatus installed in adjacent thereto is provided between the adjacent wafer polishing apparatuses.
According to this structure, three or more steps of polishing can be achieved by polishing the wafer by the one wafer polishing apparatus and thereafter transferring the wafer to the adjacent wafer polishing apparatus by the transfer apparatus so as to further polish. For example, in the case of polishing the wafer in the wafer polishing system in which two wafer polishing apparatuses are provided in parallel, the wafer is CMP processed according to the two-step polishing by one of two wafer polishing apparatuses, and the wafer can be thereafter transferred to the other wafer polishing apparatus so as to be further CMP processed according to the one-step polishing or the two-step polishing. Accordingly, the three-step polishing or the four-step polishing is executed as whole with respect to the wafer.
According to the invention described in claim 6, there is provided a wafer polishing method of polishing a wafer by the wafer polishing system as described in claim 5 in which two wafer polishing apparatuses are provided in parallel, comprising: a step of transferring the wafer to one of two wafer polishing apparatuses so as to execute a one-step polishing or a two-step polishing; a step of transferring the wafer executed the one-step polishing or the two-step polishing to the other wafer polishing apparatus by a transfer apparatus; and a step of further applying the one-step polishing or the two-step polishing to the wafer by the other wafer polishing apparatus, wherein a three-step polishing or a four-step polishing is applied as a whole to the wafer.
According to this method, after the wafer is first transferred to the one wafer polishing apparatus so as to be applied the one-step polishing or the two-step polishing, the wafer is transferred to the other wafer polishing apparatus by the transfer apparatus. Further, the one-step polishing or the two-step polishing is further applied to the wafer. Accordingly, the three-step polishing or the four-step polishing is applied to the wafer as a whole.
In the invention described in claim 1, since the polishing work is continuously carried out without generating a waiting time in both of the case of alternately carrying out the one-step polishing at two portions by using one platen, and the case of carrying out the two-step polishing by sequentially using two platens, it is possible to obtain a high throughput. Further, since two platens provided in close parallel in both of the one-step polishing and the two-step polishing is used, it is possible to achieve a compact structure having a small occupied space in addition that a productivity is improved.
Further, since the continuous polishing work is not affected by a rate of a process time for each of the polishing works in any of the one-step polishing case and the two-step polishing case, it is possible to carry out the one-step polishing or the two-step polishing having a good productivity. Particularly, after the first polishing step and the second polishing step are finished in the two-step polishing, it is possible to smoothly give way to the next polishing motion immediately, one of the first polishing step and the second polishing step is not stood to the other polishing work condition, and it is possible to well prevent a corrosion of the wafer worked surface by the waiting time.
In the invention described in claim 2, since it is possible to inhibit the abrasive agent from flying in all directions from one of two platens to the other by the partition wall, it is possible to prevent an environment pollution due to the abrasive agent flying in all directions, in addition to the effect of the invention described in claim 1. Further, there is no risk that the different kinds of abrasive agents are mixed with each other, and a working quality of the wafer is improved. Further, the wafer retention head can smoothly move between the platen and the wafer transfer apparatus without interfering with the partition wall.
In the invention described in claim 3, since the wafer carry-in means and the wafer carry-out means can move to the position corresponding to the center position of whirling of the third moving means, it is possible to accurately mount the unpolished wafer to the wafer feed position on the wafer transfer apparatus by the wafer carry-in means, in addition to the effect of the invention described in claim 1 or 2. Further, it is possible to securely carry out the polished wafer mounted to the wafer discharge position on the wafer transfer apparatus by the wafer carry-out means. Since the wafer transfer apparatus exists in the center of whirling of the third moving means, it is possible to freely position the other wafer retention head to two platens by using the third moving means even at a time when the first wafer retention head or the second wafer retention head feeds or discharges the wafer with respect to the wafer transfer apparatus.
In the invention described in claim 4, since the head cleaning apparatus is installed at the center position of whirling of the third moving means, it is possible to easily and rapidly clean the wafer retention head only by moving the wafer retention head to the center position of whirling while being compact in the structure, in addition to the effect of the invention described in claim 1, 2 or 3. Since the head cleaning apparatus exists in the center of whirling of the third moving means, it is possible to freely position the other wafer retention head to two platens by using the third moving means even at a time when the first wafer retention head or the second wafer retention head carries out the head cleaning by the head cleaning apparatus.
In the invention described in claim 5, since it is possible to carry out a plurality of (three or more) desired steps of polishing by sequentially transferring the wafer to two or more wafer polishing apparatuses so as to carry out the polishing work, it is possible to easily obtain the wafer having a high working quality.
In the invention described in claim 6, since it is possible to carry out the three-step polishing or the four-step polishing by sequentially transferring the wafer to two wafer polishing apparatuses so as to carry out the polishing work in a plurality of steps, it is possible to easily manufacture the wafer having a higher polishing quality than the conventional one while maintaining an improvement of the productivity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an embodiment according to the present invention and showing a wafer polishing system;

FIG. 2 is a plan view showing an example of a layout of a platen, a wafer transfer apparatus and the like in a wafer polishing portion according to the embodiment;

FIG. 3 is a side elevational view showing a whirl moving means and a portion near a partition wall according to the embodiment partly using a cross section;

FIG. 4 is a plan view showing an installed example of an upper wall portion of the partition wall according to the embodiment;

FIG. 5 is a plan view showing an installed example of a lower wall portion of the partition wall according to the embodiment;

FIGS. 6A to 6E show a main portion of a wafer polishing apparatus according to the embodiment, and are step diagrams explaining respective motions of a one-step polishing;

FIGS. 7A to 7J show a main portion of the wafer polishing apparatus according to the embodiment, and are step views explaining respective motions of a two-step polishing;

FIG. 8 is a plan view of a wafer polishing system exemplifying the other embodiment according to the present invention; and

FIG. 9 is a perspective view of the wafer polishing apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is provided for achieving the object that it is possible to polish the wafer at a high throughput and it is possible to reduce the occupied space without enlarging a whole of the apparatus, in the case of carrying out the one-step polishing by using one platen, or in the case of carrying out the plural-step polishing by sequentially using a plurality of platens. The present invention achieves the object mentioned above by a wafer polishing apparatus polishing a wafer by pressing the wafer retained by a wafer retention head to a polishing pad on the platen, comprising: a first platen and a second platen provided in parallel while having a gap from each other; a first wafer retention head and a second wafer retention head respectively installed above the first platen and the second platen and being movable up and down; a wafer transfer apparatus arranged between the first platen and the second platen and on which the wafer before being polished and the wafer after being polished are mounted; a first moving means moving and stopping the first wafer retention head to both positioning portions of the first platen and the wafer transfer apparatus; a second moving means moving and stopping the second wafer retention head to both positioning portions of the second platen and the wafer transfer apparatus; and a third moving means supporting the first moving means and the second moving means, and whirling around the wafer transfer apparatus so as to move and stop the first wafer retention head and the second wafer retention head respectively to the positioning portions of the second platen and the first platen, wherein the wafer polished by the first platen or the second platen is whirled and moved to the positioning portion of the second platen or the first platen so as to be polished.

Embodiment

A description will be given below of an embodiment according to the present invention with reference to FIGS. 1 to 8. The present embodiment can achieve a one-step polishing at a high throughput by being provided a first wafer retention head and a second wafer retention head respectively installed above a first platen and a second platen, arranging a wafer transfer apparatus mounting a wafer thereon between two platens, and respectively moving the first wafer retention head and the second wafer retention head to both positioning portions of two platens and the wafer transfer apparatus by a first moving means and a second moving means.
Further, it is possible to achieve a two-step polishing at a high throughput by respectively whirl moving two wafer retention heads to the platen in the opposite side by a whirl moving means (a third moving means) supporting two moving means. Further, since two platens and the moving means can be arranged compact, it is possible to achieve a reduction of an occupied area without enlarging a size of a whole of the apparatus.
FIG. 1 is a plan view showing a whole structure of a CMP system 11 according to the present embodiment. As shown in FIG. 1, the CMP system 11 is provided with a wafer polishing portion 12, a wafer cleaning portion 13 provided in one side of the wafer polishing portion 12, and a wafer storage portion 14 provided in one side of the wafer cleaning portion 13, and a cleaning apparatus 15 and a wafer storing cassette 16 are respectively installed in the wafer cleaning portion 13 and the wafer storing portion 14.
The wafer carried in the wafer polishing portion 12 is CMP processed according to a one-step polishing or a two-step polishing, the polished wafer is transferred to a carrier robot 17 so as to be fed to the wafer cleaning portion 13, and is cleaned by the cleaning apparatus 15. Further, the cleaned wafer is transferred to a carrier robot 18 so as to be fed to the wafer storage portion 14, and is stored in the wafer storing cassette 16.
Next, a description will be given in detail of a structure of the CMP apparatus 10 installed to the wafer polishing portion 12. A first platen 21 and a second platen 22 which can be rotationally driven by a motor (not shown) are provided in the wafer polishing portion 12 in parallel so as to have a predetermined interval, and a first polishing pad 24 and a second polishing pad 25 are respectively stuck to upper surfaces of the first platen 21 and the second platen 22. Further, a wafer transfer apparatus 23 is arranged between the first platen 21 and the second platen 22, and the unpolished wafer and the polished wafer are mounted to the wafer transfer apparatus 23.
Further, above the first polishing pad 24 and the second polishing pad 25, there are provided a first wafer retention head 26 and a second wafer retention head 27 which respectively press the wafer to the polishing pads 24 and 25 at predetermined pressures while retaining the wafer and can move up and down and can be rotationally driven, and feed nozzles (not shown) which respectively feed an abrasive agent onto the polishing pads 24 and 25.
Accordingly, a lower surface of the wafer is polished by pressing the wafer retained by each of the wafer retention heads 26 and 27 to an upper surface of each of the polishing pads 24 and 25 and feeding the abrasive agent onto the polishing pads 24 and 25 while rotating the polishing pads 24 and 25 and the wafer.
The wafer transfer apparatus 23 is provided with a wafer feed means 28 and a wafer discharge means 29, as shown in FIG. 2, and the wafer feed means 28 can be moved to a wafer carry-in position 31, and receives the unpolished wafer from the carrier robot at the wafer carry-in position 31 so as to feed to the wafer retention head 26 and 27. Further, the wafer discharge means 29 can be moved to a wafer carry-out position 32, and transfers the processed wafer received from the wafer retention heads 26 and 27 to the carrier robot 17.
Further, a first moving means 33 and a second moving means 34 are provided above the wafer transfer apparatus 23 and the platens 21 and 22. As a drive system of the first moving means 33 and the second moving means 34, it is possible to employ a ball screw drive system, an air cylinder drive system or the like. Further, the first wafer retention head 26 and the second wafer retention head 27 are movably supported respectively by the first moving means 33 and the second moving means 34.
Accordingly, the first wafer retention head 26 is reciprocated between the wafer transfer apparatus 23 and the first platen 21 by the first moving means 33, whereby the first wafer retention head 26 is moved to the wafer transfer apparatus 23 and the polishing positions of the first platen 21 so as to be positioned. In other words, the first wafer retention head 26 is structured such as to be moved to and stopped at the positioning portions (the polishing position and the wafer transfer position) of both the first platen 21 and the wafer transfer apparatus 23 by the first moving means 33.
In the same manner, the wafer retention head 27 is reciprocated between the wafer transfer apparatus 23 and the second platen 22 by the second moving means 34, whereby the second wafer retention head 27 is moved to the wafer transfer apparatus 23 and the polishing position of the second platen 22 so as to be positioned. In other words, the second wafer retention head 27 is structured such as to be moved to and stopped at the positioning portions (the polishing position and the wafer transfer position) of both the second platen 22 and the wafer transfer apparatus 23 by the second moving means 34.
Further, a whirl moving means 35 corresponding to the third moving means is additionally provided above the wafer transfer apparatus 23. The whirl moving means 35 supports the first moving means 33 and the second moving means 34, whirls around the wafer transfer apparatus 23, and respectively moves and stops the first wafer retention head 26 and the second wafer retention head 27 to the positioning portions (the polishing positions) of the second plate 22 and the first platen 21.
Accordingly, the first wafer retention head 26 is horizontally whirled at 180 degree around the wafer transfer apparatus 23 together with the first moving means 33 by the whirl moving means 35, thereby being rotationally moved to the polishing position of the second platen 22 in an opposite side to the first platen 21 so as to be stopped. In the same manner, the second wafer retention head 27 is horizontally whirled at 180 degree around the wafer transfer apparatus 23 together with the second moving means 34 by the whirl moving means 35, thereby being rotationally moved to the polishing position of the first platen 21 in an opposite side to the second platen 22 so as to be stopped. In this case, the wafer carry-out means 31 and the wafer carry-in means 32 mentioned above are structured at a position corresponding to the center position of whirling of the whirl moving means 35 such as to be alternately movable independently from each other.
The whirl moving means 35 has a whirl support portion (not shown) in an outer peripheral portion of a member to which the first moving means 33 and the second moving means 34 are supported, as shown in FIG. 3, and is rotationally driven by a motor (not shown). The first wafer retention head 26 and the second wafer retention head 27 are arranged in an outer peripheral portion of the whirl moving means 35 so as to face to each other.
Accordingly, the whirl moving means 35 is reciprocated at 180 degree according to a motor drive, whereby the first wafer retention head 26 and the second wafer retention head 27 are whirl moved between the first platen 21 and the second platen 22.
In the present embodiment, a partition wall 38 for preventing a liquid from flying in all directions is provided between the first platen 21 and the wafer transfer apparatus 23, and between the second platen 22 and the wafer transfer apparatus 23, in order to prevent the liquid such as the abrasive agent or the like fed to the upper surface of the first platen 21 or the second platen 22 under rotation from flying in all directions toward the second platen 22 or the first platen 21 arranged so as to oppose to the first platen 21 and the second platen 22.
As shown in FIG. 3, the partition wall 38 is constituted by an upper wall portion 39 and a lower wall portion (an auxiliary wall portion) 40. The upper wall portion 39 is attached in such a manner as to be whirled integrally with the whirl moving means 35, and the upper wall portion 39 in a plan view is constituted by a pair of vertical surface portions 41 arranged between the first platen 21 and the second platen 22, and circular arc surface portions 42 and 43 formed so as to correspond to the outer peripheral shapes of the first platen 21 and the second platen 22 from both ends of the vertical surface portion 41, as shown in FIG. 4.
Further, a passage 44 communicating between the first platen 21 and the second platen 22 is formed in an inner side of a pair of vertical surface portions 41, and the passage 44 allows the first wafer retention head 26 and the second wafer retention head 27 to move. Accordingly, the first wafer retention head 26 and the second wafer retention head 27 are formed by the passage 44 in such a manner as to be movable without interfering with the partition wall 38.
The lower wall portion 40 is constituted by a circular arc surface portion 45 fixed between the wafer transfer apparatus 23, and the first platen 21 and the second platen 22, and a horizontal surface portion 46 continuously provided in such a manner as to cover the upper surfaces of the first platen 21 and the second platen 22 from an upper end of the circular arc surface portion 45 (refer to FIG. 5).
Since the partition wall 38 is installed between the platens 21 and 22, and the wafer transfer apparatus 23, the abrasive agent fed to the upper surface of the first platen 21 or the second platen 22 during the wafer polishing is prevented from flying in all directions toward the upper surface of the second platen 22 or the first platen 21 in the opposite side. Since a prior art (not shown) is provided for cleaning the abrasive agent flying in all directions toward the wall by a pure water or the like, and the abrasive agent flying in all directions toward the wall can be cleaned before the upper wall portion 39 is moved by the whirl moving means 35, the abrasive agents respectively used in the first platen 21 and the second platen 22 are not brought in the second platen 22 and the first platen 21 even if the upper wall portion 39 is whirled.
Next, a description will be given of an operation of the present embodiment. Each of motion portions constructing the CMP system 11 is generally controlled according to a predetermined motion program by a control apparatus (not shown). FIGS. 6A to 6E show motion steps at a time of CMP processing the wafer according to the one-step polishing. In this case, as a matter of convenience for explaining, an illustration of the moving means 33, 34, and 35 is omitted in these drawings.
In this case, polishing conditions such as the abrasive agent and the like respectively set in the first platen 21 and the second platen 22 for applying the one-step polishing to the wafer in the first platen 21 and the second platen 22 are identical with each other.
First, after mounting the wafer to the wafer feed portion 28 of the wafer transfer apparatus 23 shown in FIG. 3, the first wafer retention head 26 is moved to the receiving position of the wafer transfer apparatus 23 by the first moving means 33 (FIG. 6A). Next, the first wafer retention head 26 receives the wafer on the wafer transfer apparatus 23 (FIG. 6B), the first wafer retention head 26 is moved to the polishing position on the first platen 21 by the first moving means 33 so as to start the polishing work (FIG. 6C).
During the polishing, the wafer to be polished next is mounted on the wafer transfer apparatus 23, and the second wafer retention head 27 is thereafter moved to the receiving position of the wafer transfer apparatus 23 by the second moving means 34, and receives the wafer (FIG. 6D). Further, the second wafer retention head 27 is moved to the polishing position on the second platen 22 by the second moving means 34 so as to start the polishing work (FIG. 6E).
Accordingly, the first wafer retention head 26 polishes the wafer on the first platen 21, and the second wafer retention head 27 simultaneously polishes the wafer on the second platen 22.
Next, if the polishing of the wafer on the first platen 21 is finished, the first wafer retention head 26 is moved to the positioning portion of the wafer transfer apparatus 23 by the first moving means 33 (FIG. 6A). Then, the first wafer retention head 26 discharges the polished wafer, and receives the unpolished wafer fed onto the wafer transfer apparatus 23 instead (FIG. 6B). Thereafter, the first wafer retention head 26 is moved to the polishing position on the first platen 21 by the first moving means 33 so as to start the polishing work (FIG. 6C).
On the other hand, if the polishing of the wafer on the second platen 22 is finished, the second wafer retention head 27 is moved to the positioning portion of the wafer transfer apparatus 23 by the second moving means 34. Further, the second wafer retention head 27 discharges the polished wafer, and receives the unpolished wafer fed onto the wafer transfer apparatus 23 instead (FIG. 6D).
Thereafter, the second wafer retention head 27 is moved to the polishing position on the second platen 22 by the second moving means 34 so as to start the polishing work. Accordingly, the first wafer retention head 26 again polishes the wafer on the first platen 21, and the second wafer retention head 27 simultaneously polishes the wafer on the second platen 22 (FIG. 6E). Thereafter, the one-step polishing is efficiently executed in each of the first platen 21 and the second platen 22 by sequentially repeating the series of motion steps shown in FIGS. 6A to 6E.
In other words, the first wafer retention head 26 is moved to the polishing position on the first platen 21 so as to start the polishing work after moving to the receiving position of the wafer transfer apparatus 23 so as to receive the unpolished wafer. During the while, the wafer to be polished next is mounted on the wafer transfer apparatus 23, and the second wafer retention head 27 is moved to the receiving position of the wafer transfer apparatus 23 so as to receive the wafer, and is thereafter moved to the polishing position on the second platen 22 so as to start the polishing work.
Accordingly, the first wafer retention head 26 executes the polishing work on the first platen 21, and the second wafer retention head 27 simultaneously executes the polishing work on the second platen 22. A lot of wafers can be efficiently polished by sequentially repeating the series of polishing motions.
As mentioned above, it is possible to apply the one-step polishing to the wafer in the first platen 21 and the second platen 22 in the simultaneous parallel manner. In this case, since any waiting time is not generated, a high throughput can be secured.
In the description of the one-step polishing mentioned above, the case of the one kind of wafer process is exemplified, however, the motion steps mentioned above can be applied to a case that two kinds of one-step polishing are executed to two kinds of wafers in the first platen 21 and the second platen 22 in the simultaneous parallel manner while changing the abrasive agent.
Next, FIGS. 7A to 7J show polishing motion steps in the case of CMP processing the wafer according to the two-step polishing. In this case, in order to apply the two-step polishing to the wafer by using both the first platen 21 and the second platen 22, the polishing conditions such as the abrasive agent and the like in the first platen 21 and the second platen 22 are differentiated from each other. In the illustrated embodiment, after the polishing of the first step is executed on the first platen 21, the polishing of the second step is executed on the second platen 22.
First, after mounting the wafer to the wafer feed portion 28 of the wafer transfer apparatus 23 shown in FIG. 3, the first wafer retention head 26 is moved to the transfer position on the wafer transfer apparatus 23 by the first moving means 33 (FIG. 7A). Next, the first wafer retention head 26 receives the wafer on the wafer transfer apparatus 23 (FIG. 7B), the first wafer retention head 26 is moved to the polishing position on the first platen 21 by the first moving means 33 so as to start the polishing work of the first step (FIG. 7C).
During the polishing, the wafer to be polished next is mounted to the wafer feed portion 28 of the wafer transfer apparatus 23, and the second wafer retention head 27 is thereafter moved to the receiving position of the wafer transfer apparatus 23 by the second moving means 34. Further, the second wafer retention head 27 is moved onto the wafer transfer apparatus 23 by the second moving means 34 so as to receive the wafer (FIG. 7D).
Next, if the polishing of the first step applied to the wafer is finished on the first platen 21, the first wafer retention head 26 is whirl moved to the polishing position on the second platen 22 by the whirl moving means 35 so as to start applying the polishing work of the second step to the wafer (FIGS. 7E and 7F). Further, the second wafer retention head 27 is moved to the polishing position on the first platen 21 by the second moving means 34 so as to start the polishing work of the first step (FIG. 7G).
Accordingly, the first wafer retention head 26 executes the polishing work of the second step on the second platen 22, and the second wafer retention head 27 simultaneously executes the polishing work of the first step on the first platen 21.
Further, if the polishing work of the second step applied to the wafer is finished on the second platen 21, the first wafer retention head 26 is moved to the receiving position on the wafer transfer apparatus 23 by the first moving means 33 (FIG. 7H), discharges the polished wafer, and receives the unpolished wafer fed onto the wafer transfer apparatus 23 instead.
On the other hand, if the polishing of the first step on the first platen 21 is finished, the second wafer retention head 26 is whirl moved to the polishing position on the second platen 22 by the whirl moving means 35 so as to start applying the polishing work of the second step to the wafer (FIGS. 7I and 7J). Thereafter, the first wafer retention head 26 is moved to the polishing position on the first platen 21 by the first moving means 33 so as to again start the polishing work of the first step.
Thereafter, the two-step polishing applied to the wafer is efficiently executed by sequentially repeating the series of motion steps shown in FIGS. 7A to 7J.
In the present embodiment, a head cleaning apparatus (refer to reference numeral 48 in FIG. 1) for cleaning the wafer retention heads 26 and 27 is installed in a center position of whirling of the whirl moving means 35, and the wafer feed means 28 and the wafer discharge means 29 are structured such as to be retracted from the center position of whirling to the wafer carry-in position 32 and the wafer carry-out position 32 respectively at a time of cleaning the wafer retention heads 26 and 27.
Accordingly, the cleaning process of the wafer retention heads 26 and 27 is executed by retracting the wafer feed means 28 and the wafer discharge means 29 to the desired positions from the center position of whirling and thereafter moving the wafer retention heads 26 and 27 to the head cleaning apparatus 48 installed at the center position of whirling, at a time of cleaning the wafer retention heads 26 and 27.
According to this structure, since the head cleaning apparatus 48 is installed at the center position of whirling of the whirl moving means 35, it is possible to achieve a compact structure of the whole apparatus, and it is possible to easily and rapidly clean the wafer retention heads 26 and 27 by moving the wafer retention heads 26 and 27 to the center position of whirling.
Further, since the wafer transfer apparatus 23 including the wafer feed means 28 and the wafer discharge means 29 and the head cleaning apparatus 48 exist at the center of whirling, the wafer retention head 26 (27) is positioned at the center of whirling until the wafer retention head 26 (27) mounts the processed wafer to the wafer discharge means 29, thereafter cleans by the head cleaning apparatus 48 and receives the wafer to be processed from the wafer feed means 28, whereby the other wafer retention head 27 (26) can be whirled between the first platen 21 and the second platen 22, and does not back up the polishing process.
As described above, since the present embodiment can independently and continuously execute the polishing work without generating any waiting time in both of the case that the one-step polishing is carried out by using one platen 21 or 22 and the case that the two-step polishing is carried out by sequentially using two platens 21 and 22, it is possible to obtain a high throughput.
Further, in both of the one-step polishing and the two-step polishing, it is possible to always operate two platens 21 and 22 which are provided in close parallel so as to polish. Accordingly, a productivity of the polishing work is significantly improved, and it is possible to achieve a compact structure so as to reduce an occupied space of the whole apparatus.
Further, in any case of the one-step polishing and the two-step polishing, since it is possible to smoothly apply the continuous polishing work to the wafer without being affected by the rate of the process time for each of the polishing works, it is possible to execute the one-step polishing or the two-step polishing having a good production efficiency. Particularly, since it is possible to smoothly give way to the next polishing work immediately after the first polishing step and the second polishing step are finished in the two-step polishing, one of the first polishing step and the second polishing step is neither stood to nor stopped its motion by the other polishing work condition.
In the illustrated embodiment, since the partition wall 38 is provided between each of the platens 21 and 22 and the wafer transfer apparatus 23, there is no risk that the liquid such as the abrasive agent or the like fed to one of two platens 21 and 22 flies in all directions toward the other platen 21 or 22 during the polishing work, and it is possible to always maintain the polishing environment clean.
Further, the passage 44 allowing each of the wafer retention heads 26 and 27 to move is formed in the partition wall 38, and the partition wall 38 is attached to the whirl moving means 35 so as to be integrally whirled. Accordingly, the wafer retention heads 26 and 27 can be smoothly reciprocated to the predetermined positioning portion between two platens 21 and 22 and the wafer transfer apparatus 23, without being interfered with the partition wall 38.
Further, the wafer feed means 28 and the wafer discharge means 29 can be moved to the position corresponding to the center position of whirling of the whirl moving means 35 independently from each other in alternate shifts. Accordingly, after the unpolished wafer is accurately set to the wafer feed means 28 from the carrier robot 17 at the wafer carry-in position 31, the wafer feed means 28 is moved to the position of the wafer transfer apparatus 23, and the wafer is thereafter retained efficiently by the wafer retention heads 26 and 27.
Further, after the polished wafer is set to the wafer discharge means 29 on the wafer transfer apparatus 23 by the wafer retention heads 26 and 27, the wafer discharge means 29 is moved to the wafer carry-out position 31 and is transferred to the carrier robot 17 from the wafer discharge means 29.
FIG. 8 is a plan view showing the other embodiment according to the present invention. The wafer polishing portion 12 is provided with two CMP apparatuses, that is, a first CMP apparatus 10A and a second CMP apparatus 10B having the same structure as the embodiment mentioned above in parallel. In the illustrated embodiment, the first CMP apparatus 10A and the second CMP apparatus 10B are arranged so as to form a truncated chevron shape in a plan view, and the first platen 21 of the first CMP apparatus 10A and the second platen 22 of the second CMP apparatus 10B are arranged so as to come close to each other.
Further, a transfer apparatus 49 is installed between the first CMP apparatus 10A and the second CMP apparatus 10B. The transfer apparatus 49 transfers the wafer polished by the first CMP apparatus 10A to the second CMP apparatus 10B.
As mentioned above, according to the wafer polishing system 11 in FIG. 8, it is possible to execute the CMP process according to the one-step polishing or the two-step polishing by CMP processing the wafer according to the two-step polishing by one wafer polishing apparatus 10A and thereafter transferring the wafer to the other wafer polishing apparatus 10B.
Accordingly, it is possible to apply the three-step polishing or the four-step polishing to the wafer as a whole, and it is possible to easily obtain the wafer having a high work quality. The high throughput can be achieved by respectively carrying out the same one-step polishing and two-step polishing. Further, it is also possible to simultaneously process plural kinds of wafers by independently carrying out the different one-step polishing and two-step polishing respectively.
The first moving means 33 and the second moving means 34 are shown on the basis of the linear motion in the embodiment and the description of the motion according to the present invention, however, it is sufficient to position the wafer retention head to the platen 21 (22) and the wafer transfer apparatus 23 respectively, and it is possible to obtain the effect even if the moving means carries out the whirling motion.
The present invention can be variously modified within the scope of the present invention, and it goes without saying that the present invention comes to the modified structure.

DESCRIPTION OF REFERENCE NUMERALS

10 wafer polishing apparatus (CMP apparatus)
11 wafer polishing system (CMP system)
12 wafer polishing portion
21 first platen
22 second platen
23 wafer transfer apparatus
24 first polishing pad
25 second polishing pad
26 first wafer retention head
27 second wafer retention head
28 wafer feed means
29 wafer discharge means
31 wafer carry-in position
32 wafer carry-out position
33 first moving means
34 second moving means
35 whirl moving means (third moving means)
38 partition wall
44 passage
48 head cleaning apparatus
49 transfer apparatus (distributing means)

Claims

1. A wafer polishing apparatus that polishes a wafer by pressing the wafer retained by a wafer retention head to a polishing pad on a platen, comprising:

a first platen and a second platen provided in parallel while having a gap from each other;

a first wafer retention head and a second wafer retention head respectively installed above the first platen and the second platen and being movable up and down;

a wafer transfer apparatus arranged between the first platen and the second platen and on which the wafer before being polished and the wafer after being polished are mounted;

a first moving means that moves and stops the first wafer retention head to both positioning portions of the first platen and the wafer transfer apparatus;

a second moving means that moves and stops the second wafer retention head to both positioning portions of the second platen and the wafer transfer apparatus; and

a third moving means that supports the first moving means and the second moving means, and whirls around the wafer transfer apparatus so as to move and stop the first wafer retention head and the second wafer retention head respectively to the positioning portions of the second platen and the first platen,

wherein the wafer polished by the first platen or the second platen is whirled and moved to the positioning portion of the second platen or the first platen so as to be polished.

2. A wafer polishing apparatus that polishes a wafer by pressing the wafer retained by a wafer retention head to a polishing pad on a platen, comprising:

wherein the wafer polished by the first platen or the second platen is whirled and moved to the positioning portion of the second platen or the first platen so as to be polished, a partition wall for preventing a liquid from flying in all directions is provided between the first platen and the wafer transfer apparatus, and between the second platen and the wafer transfer apparatus, a passage through which the first wafer retention head and the second wafer retention head pass is formed in the partition wall, and the partition wall is provided in such a manner as to be capable of integrally whirling with the third moving means.

3. The wafer polishing apparatus as claimed in claim 1 or 2, wherein the wafer transfer apparatus is provided with a wafer carry-in means that carries in the unpolished wafer, and a wafer carry-out means that carries out the polished wafer, and the wafer carry-out means and the wafer carry-in means are structured such as to be independently movable to a position corresponding to a center position of whirling of the third moving means.

4. The wafer polishing apparatus according to claim 1, 2 or 3, wherein the third moving means is provided so as to be retractable from the center position of whirling, and a head cleaning apparatus for cleaning the first wafer retention head and the second wafer retention head is installed at the center position of whirling.

5. The wafer polishing system provided with the wafer polishing apparatus according to claim 1 or 2, wherein two or more the wafer polishing apparatuses are provided in parallel, and a transfer apparatus for transferring the wafer polished by one wafer polishing apparatus to the other wafer polishing apparatus installed in adjacent thereto is provided between the adjacent wafer polishing apparatuses.

6. The wafer polishing method of polishing a wafer by the wafer polishing system according to claim 5 in which two wafer polishing apparatuses are provided in parallel, comprising:

a step of transferring the wafer to one of two wafer polishing apparatuses so as to execute a one-step polishing or a two-step polishing;

a step of transferring the wafer executed the one-step polishing or the two-step polishing to the other wafer polishing apparatus by a transfer apparatus; and

a step of further applying the one-step polishing or the two-step polishing to the wafer by the other wafer polishing apparatus,

wherein a three-step polishing or a four-step polishing is applied as a whole to the wafer.