JP3979451B2 - Polishing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus, and more particularly to a polishing apparatus that polishes a material to be polished such as a semiconductor wafer to a flat and mirror surface.
[0002]
[Prior art]
In recent years, as semiconductor devices are highly integrated, circuit wiring is becoming finer and the distance between wirings is becoming narrower. Along with this, the depth of focus becomes shallow when circuit formation is performed by optical lithography or the like, so that a higher flatness of the imaging surface of the stepper is required. Chemical mechanical as a means of flattening the surface of a semiconductor wafer, pressing a semiconductor wafer held by a carrier against the polishing cloth while supplying a polishing liquid containing abrasive grains to the polishing cloth affixed on a rotating turntable Polishing is taking place.
[0003]
FIG. 8 shows a polishing apparatus disclosed in Japanese Patent Laid-Open No. 9-117857, in which a pair of polishing units 101a and 101b are arranged opposite to the left and right at one end of a space on a floor that is rectangular as a whole, and the other end side. A pair of load / unload units for mounting the semiconductor wafer storage cassettes 102a and 102b are respectively arranged. A traveling rail 103 is laid on the line connecting the polishing unit and the load / unload unit, and on both sides of the traveling rail 103, there are one reversing machine 105, 106 and two washing machines 107a, 107b, 108a, 108b are arranged.
[0004]
Thus, according to the polishing apparatus in which a pair of polishing processing lines are configured on both sides of the transfer line, the normal one-stage polishing is performed in parallel in each polishing processing line to improve the efficiency. In the case of performing two-stage polishing in which the polishing liquid is changed and two-stage polishing is performed, after one polishing unit 101a is polished, one end cleaning process is performed and then moved to another polishing unit 101b to perform secondary polishing. Therefore, it is possible to selectively perform a series process for performing two-stage polishing and a parallel process for performing one-stage polishing in parallel with one apparatus.
[0005]
In the parallel processing of this polishing apparatus, the material to be polished is conveyed as follows. That is, after the polishing process of the material to be polished in the polishing units 101a and 101b is finished, the top ring 110 rotates and moves onto the pusher 112 to deliver the processed material to be polished. After the second robot 104b conveys this to the cleaning machine 107a or 107b, the unprocessed material to be polished is received from the reversing machines 105 and 106, and is transferred to the pusher 112. The top ring 110 receives this from the pusher and moves onto the turntable 109 to resume polishing. Reference numeral 111 denotes a dresser for regenerating the polished surface on the turntable 109.
[0006]
[Problems to be solved by the invention]
By the way, in order to increase the throughput in the above polishing apparatus, it is necessary to improve the operation rate of the turntable 109 that performs the polishing step that is the rate-limiting step. However, in the above conventional technique, it takes time to remove the processed material to be processed from the two pushers 112 and supply the unprocessed material to be processed by one robot 104b. The table idle time had occurred.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a polishing apparatus capable of performing parallel processing with an increased throughput by minimizing idle time of a turntable in a polishing apparatus having two polishing processing lines arranged in parallel. To do.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is a housing portion for housing a material to be polished, and at least two polishing processing lines in which a cleaning unit and a polishing unit are respectively disposed on at least two lines extending substantially in parallel from the housing portion. , Having a temporary table that is shared between the two polishing processing lines and disposed between the cleaning unit and the polishing unit, and can transfer a material to be polished between the temporary table, the polishing unit, and the cleaning unit The robot unit is provided in each of the polishing processing lines, and the polishing unit has a turntable, a top ring device, and a pusher for exchanging a material to be polished with the robot unit, and the top ring device includes: Two top rings that can be placed on the pusher and the turntable, respectively, and these two top rings can be rotated horizontally A film thickness measuring sensor for measuring the thickness of a thin film formed on the material to be polished held by the top ring located above the pusher, The polishing apparatus is characterized in that a polishing amount is obtained based on a thickness of a thin film measured by a measurement sensor, and feedback control is performed so as to adjust a polishing time of a next material to be polished .
[0009]
With such a configuration, each robot means supplies the unpolished material on the temporary table to the polishing unit, and the polished material of the polishing unit sends it directly to the cleaning unit. The polished material can be quickly replaced with an unpolished material. Accordingly, it is possible to minimize the non-operation time of the polishing unit waiting for the material to be polished, which is the rate-limiting step of the polishing apparatus, and to greatly improve the throughput of the polishing apparatus.
[0011]
This ensures that while by positioning one of the top ring on the turntable performs a polishing process, it is possible to perform the replacement of the abrasive of another top ring, non-operating time of the turntable is reduced , Improve throughput.
[0012]
This ensures that performs the calculation of the amount of polishing can be performed more fine polishing amount control based on the measured value.
[0013]
According to a second aspect of the invention, the said polishing unit, a polishing apparatus according to claim 1, characterized in that the diameter of the buffing table is provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a polishing apparatus according to the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram for explaining a first embodiment of a polishing apparatus according to the present invention. This apparatus has a rectangular space on the installation floor 10 and its components on the center line C of the installation floor. On the other hand, they are arranged symmetrically. That is, a pair of polishing units 10a and 10b are arranged opposite to the left and right on one end side of the installation floor, and a pair of load / unload units for placing the semiconductor wafer storage cassettes 12a and 12b on the other end side, respectively. In addition, a pair of secondary washers 14a and 14b, a pair of reversing machines 16a and 16b, a pair of primary washers 18a and 18b, and a pair of temporary A cradle 20 is provided. The pair of primary and secondary washing machines 14a, 14b, 18a, 18b and the reversing machines 16a, 16b are arranged to face each other across the center line, and are jointed at positions on the center line therebetween. Fixed robots 22 and 24 having arms are arranged. A pair of fixed robots 26 a and 26 b are provided on the left and right sides of the temporary placement table 20.
[0016]
Each of the polishing units 10a and 10b includes a pusher 30 for transferring the workpiece W, a top ring device 36 having two top rings 32 and 34, a turntable 38 having a polishing tool surface on the surface, and a polishing tool surface. The dresser 40 for sharpening is arranged substantially parallel to the center line. In this example, a small-diameter buffing table 42 for buffing is provided on the side of the top ring device 36.
[0017]
Hereinafter, a substantial configuration of the polishing units 10a and 10b will be described with reference to FIG. The top ring device 36 includes a vertically extending column 50 that is rotatably supported by a base 48 attached to a bracket 46 that protrudes laterally from the base 44 of the turntable 38, and a horizontal direction at the tip of the column 50. And a pair of top rings 32 and 34 respectively attached to the ends of the swivel arm 52. The top rings 32 and 34 have a function of adsorbing the material to be polished to the lower surfaces of the top rings 32 and 34, and can be independently rotated in a horizontal plane by a drive motor 56 and can be raised and lowered by an air cylinder 58. A polishing liquid supply nozzle is opened at a predetermined position on the upper surface of the turntable.
[0018]
The pusher 30 is located on the side opposite to the turntable 38 with respect to the support column 50. When one top ring 32 (34) is in a polishing position on the turntable 38, the other top ring 34 (32) It is located directly above the pusher 30. The pusher 30 is provided with a workpiece mounting table 60 that can be moved up and down, and assists the transfer of the workpiece between the top rings 32 and 34 and the robots 26a and 26b. A support column 64 of the dresser 40 is rotatably supported on a bracket 62 that protrudes on the opposite side of the base 44 of the turntable 38 from the top ring device 36.
[0019]
As shown in FIG. 3, the small-diameter buffing table 42 is approximately the same size as the material to be polished, and is approximately the same distance as the polishing position of the pusher 30 or the turntable 38 with respect to the center of the column 50 of the top ring device 36. It is in. Here, normally, the final polishing using a polishing liquid containing abrasive grains or the final polishing and cleaning using pure water is performed. Since the buffing table 42 is approximately the same size as the material to be polished, the swivel arm 52 is swung to perform the polishing with the centers of the materials appropriately shifted. In order to stabilize the posture of the material to be polished, It is preferable to control so that the center of the abrasive does not deviate from the surface of the buffing table 42.
[0020]
As shown in FIG. 4, the temporary placing table 20 is configured in two upper and lower stages, the upper side is a dry station 20A for placing a dry material to be dried, and the lower side is a wet material for placing a wet material to be dried while preventing drying. Station 20B. Although the dry station 20A is open, the wet station 20B is a closed type covered with a box body 68 because it has spray nozzles 66 arranged above and below the material to be polished, and from an open / close gate 70 provided on the side surface. The workpiece W is put in and out.
[0021]
The types of the cleaning machines 14a, 14b, 18a, and 18b are arbitrary. For example, the primary cleaning machines 18a and 18b on the polishing units 10a and 10b side wipe the semiconductor wafer front and back surfaces with a roller with a sponge. The secondary cleaning machines 14a and 14b on the side of 12a and 12b hold the edge of the semiconductor wafer and supply the cleaning liquid while rotating in the horizontal plane. The latter also has a function as a dryer for drying by centrifugal dehydration.
[0022]
In this embodiment, the reversing machines 16a and 16b are necessary in relation to the storage method of the cassettes 12a and 12b and the gripping mechanism of the robot. However, the reversing machines 16a and 16b are always transferred with the polishing surface of the semiconductor wafer facing downward. In case it is not necessary. Further, it is not necessary in the case of a structure in which the robot has a reversing function. In this embodiment, the two reversing machines 16a and 16b are selectively used for handling a dry semiconductor wafer and for handling a wet semiconductor wafer.
[0023]
In this embodiment, four robots 22, 24, 26a, and 26b are provided, each of which is fixed, and is of a type in which a joint arm having a hand at the tip moves. The first robot 22 conveys the material to be polished between a pair of cassettes, secondary cleaning machines 14a and 14b, and reversing machines 16a and 16b. The second robot 24 transfers materials to be polished between the pair of reversing machines 16a and 16b, the primary cleaning machines 18a and 18b, and the temporary placement table 20. In addition, the third and fourth robots 26 a and 26 b exchange materials to be polished between the temporary table 20, any of the primary cleaning machines 18 a and 18 b, and any of the pushers 30.
[0024]
In the polishing apparatus having such a configuration, both series processing and parallel processing are performed. FIG. 1 shows the flow of a semiconductor wafer when parallel processing is performed using one cassette in the load / unload unit. In this description, with respect to the elements provided in a pair with the center line C in between, the elements located on the upper side in FIG.
[0025]
The flow of the material to be polished (semiconductor wafer) in the parallel processing of the right side polishing processing line is as follows.
Right cassette 12a → first robot 22 → dry reversing machine 16a → second robot 24 → dry station 20A → third robot 26a → pusher 30 of right polishing unit 10a → top ring 32 or 34 → turn table 38 Polishing → (Buffing with buffing table 42) → Pusher 30 → Third robot 26a → Primary cleaning machine 18a → Second robot 24 → Wet reversing machine 16b → First robot 22 → Secondary cleaning machine 14a , 14b → right cassette 12a
[0026]
The flow of processing in each polishing unit 10a, 10b will be described with reference to FIG. A new unpolished wafer is already prepared in the pusher 30 by the third robot 26a (or the fourth robot 26b). As shown in FIG. 5A, the polishing is performed by holding the wafer with the top ring 32, while the other top ring 34 is on the pusher 30 and receives the unprocessed wafer from the pusher 30. When the main polishing process is completed at the turntable 38, the top ring 32 moves onto the buffing table 42 by the turning of the turning arm 52, as shown in FIG. Can be performed. Of course, it is also possible to transfer to the pusher 30 immediately after the main polishing process.
[0027]
When the water polishing is finished, the top ring device 36 is operated to turn the turning arm 52 and move the top ring 32 directly above the pusher 30 as shown in FIG. Then, the top ring 32 is lowered or the pusher 30 is raised, and the polished wafer is transferred to the pusher 30. The polished wafer is replaced with a new unpolished wafer by the third robot 26a (or the fourth robot 26b). During this time, the other top ring 34 is moved to the polishing position on the turntable 38 and is polished by the turntable 38. As shown in FIG. Here, water polishing for final polishing and cleaning is performed, and the process returns to the step (a) in FIG.
[0028]
In this process, since the robots 26a and 26b for putting the material into and out of the polishing units 10a and 10b are provided for each polishing processing line, the processed material to be processed by the pusher 30 is not processed quickly. Replaced with the material to be polished. Therefore, it is not necessary for the top rings 32 and 34 to wait for the arrival of the next material to be polished, and the idle time during which the turntable 38 is not performing the polishing operation is reduced.
[0029]
Further, in this embodiment, each top ring device 36 has two top rings 32 and 34 mounted on both ends of the turning arm 52, so that the other top rings 32 and 34 of the other top ring 32 and 34 are polished during the polishing process. By exchanging the material to be polished with an untreated material, idle time for attaching the material to be polished to the top rings 32 and 34 does not occur. Therefore, high throughput parallel processing with high operating efficiency of the turntable 38 can be performed.
[0030]
The throughput of parallel processing by the apparatus of FIG. 1 is shown in comparison with the conventional case shown in FIG. Here, the polishing time per sheet was set to 2 minutes, and the cleaning was performed in a two-stage cleaning in which both the primary and the secondary were sequentially performed. In the conventional case, it was 40 sheets per hour, but in the case of the present invention, it was 53 sheets. Furthermore, when comparing the throughput per unit floor area for the entire device, while the case of the conventional 7.4 Like / m ² · hr, the present invention was 7.9 Like / m ² · hr .
[0031]
FIG. 6 illustrates the flow of the material to be polished when two-stage polishing is performed using the polishing apparatus of the above embodiment, that is, when series processing is performed. The outline of the flow is as follows.
Right cassette 12a → first robot 22 → dry reversing machine 16a → second robot 24 → dry station 20A → third robot 26a → first polishing unit 10a → third robot 26a → right primary cleaning machine 18a → Second robot 24 → wet station 20B → third robot 26b → secondary polishing unit 10b → third robot 26b → left primary cleaning machine 18b → second robot 24 → wet reversing machine 16b → first robot 22 → Left secondary washing machine 14b → first robot 22 → right cassette 12a
[0032]
In this series processing, since the wet wafer is supplied to the polishing unit 10b, the dry station 20A and the wet station 20B are used properly. In the wet station 20B, the rinsing liquid is supplied from the nozzle 66 to the upper and lower surfaces of the material to be polished W to prevent the material to be polished from drying. In FIG. 6, the dry station 20 </ b> A and the wet station 20 </ b> B are separately shown for convenience, but these actually overlap each other as described in FIG. 4.
[0033]
FIG. 7 shows another embodiment of the present invention. In this polishing unit, the thickness of the thin film formed on the material to be polished at a position close to the top ring 34 positioned on the pusher 30 is shown. Is provided with a film thickness measuring device 72 for measuring. The film thickness measuring device 72 includes, for example, an arm 76 having an optical head 74 that can measure the thickness of a thin film in a non-contact manner, and an XY for scanning the arm along the surface to be polished. And a positioning device 78 such as a table.
[0034]
In the polishing apparatus having such a configuration, the thickness of the thin film formed on the polished wafer held by the top ring 34 can be measured when the revolving arm 52 is reversed. Therefore, knowing the polishing amount based on this measured value, feedback control is performed so as to adjust the polishing time of the next material to be polished (wafer), or if this does not reach the allowable value, the polishing is performed again. Can be controlled. In other words, once the polishing is completed, the amount of polishing can be increased at the upper portion of the pusher, and it is not necessary to provide a separate space for measuring the amount of polishing. Since the time required for the third or fourth robot 26a, 26b to replace the polished wafer is usually shorter than the time required for polishing on the turntable 38, the difference in time is used to measure the thickness. If done, the occurrence of downtime is also prevented.
[0035]
【The invention's effect】
As described above, according to the present invention, the unpolished workpiece on the temporary table is supplied to the polishing unit by the robot means, and the polished workpiece of the polishing unit is directly sent to the cleaning unit. Therefore, it is possible to quickly replace the polished material in the polishing unit with an unpolished material, thus minimizing the non-operation time due to the polishing unit waiting for the polishing unit, which is the rate-limiting step of the polishing apparatus. It is possible to perform parallel processing with a reduced throughput.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing the flow of a polishing apparatus and a material to be polished according to the present invention.
FIG. 2 is a front view showing a polishing unit of the polishing apparatus according to the present invention.
FIG. 3 is a plan view showing a polishing unit.
FIG. 4 is a cross-sectional view showing a configuration of a temporary placement table.
FIG. 5 is a plan view showing the operation of the polishing unit.
FIG. 6 is a plan view schematically showing a flow of another aspect of the material to be polished in the polishing apparatus of the present invention.
FIG. 7 is a front view showing another embodiment of the polishing unit of the polishing apparatus according to the present invention.
FIG. 8 is a plan view schematically showing a conventional polishing apparatus.
[Explanation of symbols]
10a, 10b Polishing units 12a, 12b Housing portions 14a, 14b, 18a, 18b Cleaning unit 20 Temporary placement table 26a, 26b Robot means 30 Pusher 32, 34 Top ring 36 Top ring device 38 Turn table 42 Polishing table 52 Turning arm W Covered Abrasive

Claims (2)

An accommodating portion for accommodating the material to be polished;
At least two polishing processing lines in which a cleaning unit and a polishing unit are respectively disposed on at least two lines extending substantially in parallel from the container;
A temporary storage table shared between the two polishing processing lines disposed between the cleaning unit and the polishing unit;
Robot means capable of transporting the material to be polished between the temporary table, the polishing unit and the cleaning unit are provided in each of the polishing processing lines .
The polishing unit has a turntable, a top ring device, and a pusher for transferring a material to be polished with the robot means,
The top ring device has two top rings that can be respectively arranged on the pusher and the turntable, and a pivot arm that supports the two top rings so as to be horizontally rotatable,
A film thickness measurement sensor for measuring the thickness of a thin film formed on the material to be polished held by the top ring positioned above the pusher is provided, and the thickness of the thin film measured by the film thickness measurement sensor A polishing apparatus characterized in that a polishing amount is obtained based on the feedback and feedback control is performed so as to adjust the polishing time of the next material to be polished . The polishing apparatus according to claim 1 , wherein the polishing unit is provided with a small-diameter buffing table.

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