JP4260251B2 - Wafer polishing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for polishing a surface of a semiconductor wafer such as a bare wafer, a device wafer, an SOI wafer, a magnetic head wafer, and a magnetic disk wafer.
[0002]
[Prior art]
As this type of polishing equipment, an index head that rotatably supports the chuck mechanism is disposed above a base having a polishing disk, and the wafer is held by the chuck mechanism and the held wafer is pressed against the polishing disk. In addition, there is known a configuration in which a polishing disk and a chuck mechanism are rotated relative to each other to polish a wafer.
[0003]
More specifically, FIG. 7 shows an example of an apparatus that we describe in the specifications of Japanese Patent Application Nos. 10-234870 and 10-208540, and this polishing apparatus has three polishing discs (hereinafter referred to as “three polishing discs”) on a base 100. 110 and a pedestal 120 of one wafer W are arranged on the same circumference around an arbitrary point O so as to form an angle of 90 ° with respect to the point. A rotating shaft 180 having a rotating shaft core as a rotating shaft core is projected from the base 100, and the four chuck mechanisms 130 are arranged around the rotating shaft 180 so as to form an angle of 90 ° with the rotating shaft 180, and An index head (indicated by broken lines in the figure) 140 that supports these in a rotatable manner is supported in a rotatable manner, and the five wafers W placed on the cradle 120 by the transfer robot 150 are each chucked. Held in a batch by the mechanism, The index head 140 is rotated by 90 ° and guided to each polisher, the wafer W is pressed by each polisher, and the chuck mechanism and the polishing disk are rotated to polish the surface of the wafer W. . In the figure, reference numerals 160a and 160b denote cassettes on which wafers W before and after polishing are loaded, and 170 denotes a pad conditioner provided with each polisher.
[0004]
The wafer W whose surface has been polished through all the polishers 110 has been transferred to the cassette 160b by the transfer robot 150 after being placed on the cradle 120 again.
The chuck mechanism 130 that has released the holding of the wafer W guides a rotating brush (not shown) to the holding surface, and rotates this to clean the surface so that dust and dirt attached in the polishing process can be wiped off. It was.
[0005]
[Problems to be solved by the invention]
Cleaning the holding surface of the chuck mechanism 130 with a rotating brush is indispensable for reliably holding a new wafer W and ensuring flatness of the polished wafer W, but the rotating brush is parallel to the cassette side. If it is provided so as to be able to move forward and backward from a location located in the position, the structure of the apparatus becomes complicated, and there is a problem that the entire polishing apparatus cannot be made compact.
[0006]
In view of the above-described problems of the prior art, the present invention is an apparatus for polishing a semiconductor wafer, which can be integrated with a rotating brush to reduce the size of the apparatus and can perform an efficient polishing process. The challenge is to do so.
[0007]
[Means for Solving the Problems]
A wafer polishing apparatus according to the present invention for solving the above-described problems includes a base having a plurality of (n groups; where n is an integer of 2 to 4) polishing disks arranged on the same circumference, An index head that rotatably supports a plurality of (n + 1) chuck mechanisms on a rotating shaft above a base, a wafer before polishing transferred from a cassette, and a wafer after polishing transferred by a chuck mechanism In a wafer polishing apparatus that includes a wafer cradle to be mounted, holds the wafer from the back surface with a chuck mechanism, and polishes the wafer surface by pressing the surface against a polishing disk, the rotation shafts of the plurality of chuck mechanisms are The circumference connecting the center lines is on the circumference, and the cradle is a wafer receiving plate and a rotating brush for cleaning the chuck mechanism that are integrally arranged in a straight line, and the receiving plate and the rotating brush. The cradle with Provided retractably in the direction, vertical plane of the linear direction of the cradle back and forth is a below the index head, that the cradle so as to intersect on the circumference is provided retractably in the linear direction It is characterized by.
[0008]
In the above structure, arranged rails appropriate length to the base, the frame provided reciprocally linearly moves along the rail, the wafer and the receiving plate to be mounted with the rotary brush arranged in series to the linear movement direction Form a cradle.
[0009]
Further, in the above configuration, the wafer placed on the cradle is held by the chuck mechanism at a position where the circumference and the cradle intersect, and the wafer before polishing is removed from the cassette on one side of the rail across the intersecting portion. The wafer is transferred to the cradle and the polished wafer is transferred from the cradle to the cassette on the other side.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on the illustrated embodiments.
FIG. 1 shows the configuration of an embodiment of the polishing apparatus of the present invention. In the figure, reference numeral 1 is a base, 2a, 2b and 2c are polishers, and 3, 3 and 3 are pad conditioners attached to each polisher. 4 is a cradle for receiving a wafer, 5 is an index head, 6a, 6b, 6c and 6d are chuck mechanisms, 7a and 7b are cassettes loaded with wafers W, 8a and 8b are transfer robots, 9 is a wafer cleaning mechanism, W is a wafer.
[0011]
The base 1 is provided with three polishers 2a to 2c and a pad conditioner 3 on the upper surface thereof.
Each polisher is arranged on the circumference of a circle C centering on an arbitrary point O on the upper surface of the base 1, the polisher 2a and the polisher 2c are in opposite positions across the point O, and the polisher 2b is from both the polishers. They are arranged at equally spaced positions, that is, at positions that are at an angle of 90 ° to the point O.
When a later-described cradle 4 is positioned on the circumference of the circle C, the polisher 2b and the cradle 4 are opposed to each other at an angle of 180 ° with the point O interposed therebetween.
[0012]
Each polisher has a polisher 2a for rough polishing, a polisher 2b for intermediate finish polishing, and a polisher 2c for finish polishing. As shown in FIG. A polishing cloth 11 is affixed on the surface. Each polisher is provided with a pad conditioner 3 that advances and retracts linearly on the upper surface of the polishing pad 11 and rotates to repair the polishing pad 11.
[0013]
The cradle 4 is formed by integrating two receiving plates 12 and 12 on which the wafers W before and after polishing are mounted and one rotating brush 13 for cleaning the chucking surface of the chuck mechanism, and the side of the polisher. It is provided so that it can slide and move linearly.
More specifically, as shown in FIGS. 4 to 6, the cradle 4 includes the cradle plates 12, 12, the rotating brush 13, and the frame 14 that supports them. It is configured to be connected to the installed drive mechanism 15 via a connecting plate 15e.
[0014]
The receiving plates 12 and 12 are formed of a circular plate having a locking member 12a projecting from the periphery so that the wafer W can be placed on the upper surface thereof.
The rotating brush 13 is provided with a substantially cruciform disk 13b with a brush 13a projecting upward and fixed to a rotating shaft connected to a driving shaft of a motor 13c so as to be rotatable.
The frame 14 has a box shape, and on the upper surface thereof, the receiving plates 12 and 12 and the rotating brush 13 are arranged in series along the moving direction of the cradle 4, and the drive motor 13c of the rotating brush 13 is fixed therein. It is.
[0015]
The drive mechanism 15 is provided with a rail 15a having an appropriate length in the base 1 and a movable body 15b is slidably mounted on the rail. The movable body 15 is moved along the rail by a servo motor 15c and a ball screw rod 15d. It is provided so that it can reciprocate. The rail 15a is installed at a position slightly crossing the outer circumference of the circle C (see FIG. 4).
[0016]
The frame 14 is integrally connected to the moving body 15b of the drive mechanism 15 via a connecting plate 15e, and the cradle 4 is reciprocated linearly along the rail along with the moving body 15b on the side of the rail 15a. and, as shown in FIG. 4, when the cradle 4 is in the substantially central portion of the rail 15a is to intersect the outer periphery of the circle C, 2 groups receiving plate 12, 12 constituting the chucking mechanism the positioned below the suction mechanism 23, when the cradle 4 is on both ends of the rail 15a is adapted to be positioned substantially outside the circle C.
Also, when moving to the end of the cassette 7b side of the receiving table 4 garage Lumpur 15a (FIG. 4 right end in), the rotary brush 13 so as to positioned below one side of the suction mechanism 23 Yes.
[0017]
The index head 5 has a center point O of the circle C as a rotation axis, and is rotatably supported by a hollow rotation shaft 16 protruding above the base 1 (see FIG. 2). The four sets of chuck mechanisms 6a to 6d are equally spaced apart from each other at a position along the substantially circumference of the circle C at the lower part, that is, with the positions shifted by 90 ° with respect to the point O.
In the hollow portion of the rotary shaft 16, as shown in FIG. 2, the vacuum pump 17, a compressor 18 and the cleaning liquid tank 19, utilities tube 21a of the eight rigidity to connect the switching-off valve 20 is It is inserted, and necessary services such as reduced pressure air, pressurized air, and cleaning liquid can be supplied to each chuck mechanism via a flexible tube 22 described later.
As shown in FIG. 1, the circle C is also a circle C connecting the center lines of the rotation shafts 24 of the suction mechanisms 23 of the plurality of chuck mechanisms 6a to 6d.
[0018]
Each chuck mechanism is configured to operate integrally with two adsorption mechanisms 23 as a set.
Each suction mechanism 23 is attached downward near the edge of the index head 5, and as shown in FIG. 3, a circular frame is formed at the tip of a hollow rotating shaft 24 into which a rigid service tube 21b is inserted. A head 25 made of a material is attached, and a suction plate 26 having a large number of small holes 26a is mounted in the frame of the head 25, and rotated around a vertical axis by a motor 27 disposed above the index head 5. Similarly, the air cylinder 28 gives a back and forth movement in the vertical axis direction, and the above-mentioned service tube 23 is connected to the service tube 21 of the index head 5 through the flexible tube 22 so as to be used in the head. It is formed so as to be able to supply a hand, and is connected to the vacuum pump 17 through the service pipes 21a and 21b and the flexible pipe 22, and the inside of the head is depressurized by the vacuum pump to suck the wafer W. Adsorbed to 6, it is provided so as to be able to hold it.
Further, the compressor 18 and the cleaning liquid tank 19 are also connected by switching the opening / closing valve 20. The cleaning liquid cleans the small holes 26a of the suction plate 26, and the pressurized gas facilitates the separation of the wafer W from the suction plate 26.
[0019]
The cassette 7a is loaded with unpolished wafers W. When the cradle 4 is located on the cassette side, the wafers W in the cassette are sequentially transferred to the cradle 4 by the transfer robot 8a. It has become.
The cassette 7b is loaded with a polished wafer W. When the cradle 4 is located on the cassette side, the wafer W that has undergone the polishing process is transferred from the cradle 4 by the transfer robot 8b. It is to be transferred.
[0020]
The wafer cleaning mechanism 9 is for cleaning the polished wafer W by ejecting a cleaning liquid onto the wafer W.
[0021]
Next, the polishing process of the wafer W by the polishing apparatus of this embodiment configured as described above will be described.
[0022]
(1) First, the transfer robot 8 a is operated to transfer the wafer W before polishing from the cassette 7 a to the receiving table 4.
The cradle 4 is placed at the end of the rail 15a on the cassette 7a side, that is, the position of the cradle 4 shown by a solid line in FIG. 1, and the wafer W is transferred from the cassette 7a to the right receiving plate 12 of the cradle 4 by the transfer robot 8a. Transport and place. Subsequently, the cradle 4 is moved to the right by one wafer, and the wafer W is transferred from the cassette 7a to the left receiving plate 12.
Next, after the cradle 4 is moved along the rail 15a to the front of the index head 5, the chuck mechanism 6a is lowered at that position, and the two wafers W placed on the cradle 4 are sucked and held. Then, the chuck mechanism is raised. The chuck mechanism 6a holds the wafer W from the back surface.
[0023]
(2) The index head 5 is rotated 90 ° clockwise in FIG. 1 to guide the wafer W held by the chuck mechanism 6a onto the first polisher 2a, and the chuck mechanism 6a is lowered to polish the wafer W. The surface of the wafer W is roughly polished by pressing against 2a and rotating the rotary shafts 10 and 24. After the polishing, the chuck mechanism 6a is raised and moved on the polisher.
During this time, the cradle 4 is returned to the end position on the cassette 7a side, and the wafer W is sequentially placed on the right and left receiving plates 12 and 12 of the cradle 4 in the same manner as described above. 4 is moved along the rail 15 a to the center of the index head 5, the two wafers W are attracted and held by the chuck mechanism 6 b, and then the chuck mechanism is raised above the receiving table 4.
[0024]
(3) The index head 5 is rotated by 90 ° in the same direction as described above, the wafer W held by the chuck mechanism 6a is placed on the second polisher 2b, and the wafer W held by the chuck mechanism 6b is put on the first polisher. Each of the chuck mechanisms 6a and 6b is moved down, and the intermediate finish polishing of the wafer W is performed by the polisher 2b, and the rough finish polishing of the wafer W is performed by the polisher 2a. When the polishing is finished, each chuck mechanism is raised and moved onto the polisher.
During this time, the cradle 4 is returned to the end position on the cassette 7a side, new wafers W are sequentially placed on the cradle 4 from the cassette 7a in the same manner as described above, and the cradle 4 is further moved to the center of the index head 5 to After the two wafers W are sucked and held by the mechanism 6 c, the chuck mechanism is raised above the receiving table 4.
[0025]
(4) The index head 5 is further rotated by 90 ° in the same manner as described above to place the wafer W held by the chuck mechanism 6a on the third polisher 2c and the wafer W held by the chuck mechanism 6b on the second polisher. The wafer W held on the chuck mechanism 6c is guided onto the first polisher 2a on the 2b, the chuck mechanisms 6a, 6b and 6c are lowered, and the polishing of the wafer W is performed by the polisher 2c. The wafer W is subjected to intermediate finish polishing, and the polisher 2a performs rough finish polishing of the wafer W. When polishing is completed by each polisher, each chuck mechanism is raised and moved onto the polisher.
During this time, the cradle 4 is returned to the end position on the cassette 7a side, new wafers W are sequentially placed on the cradle 4 from the cassette 7a in the same manner as described above, and the cradle 4 is further moved to the center of the index head 5 to After the two wafers W are attracted and held by the mechanism 6 d, the chuck mechanism is raised above the receiving table 4.
After the wafer W is attracted to the chuck mechanism 6 d, the cradle 4 is fixed to the central portion of the index head 5.
[0026]
(5) Further, the index head 5 is rotated by 90 ° in the same manner as described above, the wafer W polished by the third polisher 2c is guided onto the cradle 4, the chuck mechanism 6a is lowered, and vacuum suction is stopped and rotated. Pressurized air is sent into the shaft 24 to place both wafers W on the receiving plates 12 and 12 of the receiving table 4, and a cleaning liquid is ejected from the wafer cleaning mechanism 9 to clean the suction surface (back surface) of the wafer W.
[0027]
When the polished wafer W is placed on the cradle 4, the cradle 4 is moved from the center of the index head 5 to the right side by one wafer in FIGS. 1 and 4, and the cradle 4 is moved by the transfer robot 8b. The wafer W placed on the right receiving plate 12 is transferred to the cassette 7b. During this time, the rotating brush 13 is brought into contact with the suction surface of the suction mechanism 23 on one side (left side) of the chuck mechanism 6a, and the brush is rotated. The dirt is wiped off by rubbing, and then the cradle 4 is further moved to the right by one wafer, and the wafer W placed on the cradle 12 on the left side of the cradle 4 is transferred to the cassette 7b by the transfer robot 8b. During this time, the rotating brush 13 is brought into contact with the suction surface of the suction mechanism 23 on the other side (right side) of the chuck mechanism 6a, and the brush is rotated and rubbed to wipe off the dirt. As described above, the suction surface of the chuck mechanism 6a is cleaned by the rotating brush 13 while the polished wafer W is transferred to the cassette 7b.
[0028]
Then, after the cleaning of the chuck mechanism 6a by the rotating brush 13 is completed, the cradle 4 is moved to the end on the cassette 7a side to place a new wafer W, and again moved to the center of the index head 5, and the new wafer W is moved. It is adsorbed to the chuck mechanism 6a. After the wafer W is attracted to the chuck mechanism 6a, the cradle 4 is fixed to the central portion of the rail 15a.
[0029]
During these periods, the wafer W polished by the second polisher 2b is attracted to the third polisher 2c, the wafer W polished by the first polisher 2a is attracted to the second polisher 2b, and the chuck mechanism 6d. Each wafer W is guided to the first polisher 2a, the chuck mechanism is lowered, and the wafer W is polished by each polisher in the same manner as described above.
[0030]
(6) Thereafter, in the same manner, the wafer W is transferred from the cassette 7a, transferred to the cassette 7b as the index head 5 is rotated every 90 ° and the cradle 4 is moved, and the rotating brush 13 on the suction surface of the chuck mechanism. The wafer W is continuously polished while performing cleaning and polishing by each polisher.
[0031]
In addition, the said form is only an example and arrangement | positioning and the number of polishers and chuck mechanisms can be set as appropriate.
For example, the index head 5 in the step (6) may be rotated by 270 ° in the reverse direction (counterclockwise). The cleaning of the chuck mechanism by the rotating brush 13 may be performed in an order different from the above, and the receiving mechanism 4 may be moved regardless of the transfer of the wafer W and the chuck mechanism may be cleaned by the rotating brush 13.
[0032]
In the transfer of a new wafer W, the cradle 4 is not moved to the right side of one wafer, but the left side of the pair of left and right cassettes 7a and 7a is turned by the rotation of the transfer robot 8a about the axis center. The wafer W transferred from the cassette 7 a may be mounted on the right receiving plate 12 on the receiving table 4, and the wafer W transferred from the right cassette 7 a may be mounted on the left receiving plate 12 on the receiving table 4. . When the wafer W is placed on the left and right receiving plates 12 from the left cassette 7a and the cassette W becomes empty, the width of the rotation of the transfer robot 8a at the center of the axis is widened. W may be placed on the cradle 4.
[0033]
Furthermore, it is desirable to finish the polishing in each of the polishers at the same time. Therefore, the start time of finish polishing in the third polisher 2c, which requires a relatively short polishing time, is delayed from the start time of rough polishing in the first polisher 2a and intermediate finish polishing in the second polisher 2b. You may adjust so that grinding | polishing may be complete | finished simultaneously with a polisher.
[0034]
Different types of wafers W can be stored in the respective cassettes 7a and 7a and polished. Further, when the demand for the wafer W is small, only one of the pair of suction mechanisms constituting the chuck mechanism may be operated and the other may not be operated.
[0035]
As an aspect of the apparatus of the present invention, the polishing stage (polisher) is n (n is an integer of 2 to 5), loading (transfer of the wafer before polishing from the cassette), unloading (transfer of the wafer after polishing to the cassette) ) Is one stage and the whole is an (n + 1) stage, the rotation of the index head is 360 / (n + 1) degrees and the chuck mechanism is an (n + 1) base. That is, when the polishing stage is two stages of rough polishing and finish polishing, there are three chuck mechanisms and the index head rotates 120 degrees.
[0036]
【The invention's effect】
As described above, the wafer polishing apparatus of the present invention is provided with two receiving plates and one rotating brush integrally arranged in parallel on the receiving table, and these are provided on the supporting table so that they can reciprocate linearly. Therefore, as compared with the case where the rotary brush is driven as a separate body, the apparatus can be configured more compactly to transfer the wafer and clean the chuck mechanism.
[0037]
In addition, since the receiving plate is formed by arranging the receiving plate on which the wafer is placed and the rotating brush in series along the moving direction, the chucking surface of the chuck mechanism is cleaned by the rotating brush simultaneously with the transfer of the wafer to the cassette. Thus, the polishing process can be made more efficient and the entire processing time can be shortened.
[0038]
The cradle is slidable along the rail provided on the base so that the wafer can be attracted to the chuck mechanism at the center of the rail, and the wafer can be transferred to the cassette on both sides. By doing so, a cassette for storing wafers before and after polishing and a transfer robot for transferring the wafer before and after polishing are arranged on both sides of the rail, so that the wafer can be efficiently transferred between the cradle and the cassette.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of an embodiment of a polishing apparatus of the present invention.
FIG. 2 is a schematic cross-sectional view of the polishing apparatus of FIG.
FIG. 3 is a diagram illustrating a configuration of a chuck mechanism.
FIG. 4 is a diagram showing a configuration of a cradle.
5A and 5B show a rotating brush attached to a cradle, in which FIG. 5A is a schematic plan view thereof, and FIG. 5B is a cross-sectional view taken along line V-V in FIG.
6 is a schematic cross-sectional view taken along the line VI-VI in FIG.
FIG. 7 is a plan view showing a configuration of a conventional polishing apparatus.
[Explanation of symbols]
1 base
2a ~ 2c Polisher (Polisher)
4 cradle
5 Index head
6a-6d chuck mechanism
7a, 7b cassette
8a, 8b Transfer robot
13 Rotating brush
15 Drive mechanism
15a Rail O Center C Circle W Wafer

Claims (3)

A base having a plurality of (n groups; n is an integer of 2 to 4) polishing machines arranged on the same circumference, and a plurality (n + 1) of chuck mechanisms are rotated above the base. An index head that is freely supported on a rotating shaft, a wafer cradle on which a wafer before polishing transferred from a cassette and a wafer after polishing transferred by a chuck mechanism are placed, and the wafer is chucked from the back surface. In the wafer polishing apparatus that holds the mechanism and presses the surface against the polishing disk to polish the wafer surface, a circumference connecting the center lines of the rotation axes of the plurality of chuck mechanisms is on the circumference, and the receiving The stand is a wafer receiving plate and a rotating brush for cleaning the chuck mechanism that are integrally arranged in a straight line, and a receiving table in which the receiving plate and the rotating brush are arranged in parallel is provided so as to freely advance and retract in a linear direction. A vertical descent of the cradle Faces a below the index head, a polishing apparatus of a wafer, characterized in that the cradle is provided retractably in a linear direction so as to cross over the circumference. A rail with an appropriate length is arranged on the base, and a receiving plate on which a wafer is placed and a rotating brush are arranged in series in the linear movement direction on a frame that can be reciprocated linearly along the rail. The wafer polishing apparatus according to claim 1. At the position where the circumference and the cradle intersect , the wafer placed on the cradle is held by the chuck mechanism, and the wafer before polishing is transferred from the cassette to the cradle on one side of the rail across the intersection. The wafer polishing apparatus according to claim 1 , wherein , on the other side, the polished wafer is transferred from a receiving table to a cassette.

Images