JP2002270556A - Wafer polishing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer polishing apparatus capable of automatically flatly dressing a polishing pad based on a measured result by automatically measuring a surface shape of the pad. SOLUTION: The wafer polishing apparatus comprises a displacement measuring unit 88A mounted at a polishing head 38A. The measuring unit 88A has a stylus 90 vertically moving with respect to the surface of a polishing surface platen 34A. The head 38A is horizontally moved in a state in which the stylus 90 is contacted with the surface of the polishing pad 34a, and the displacement of the stylus 90 at each point is measured. The surface shape of the pad 34a is obtained from the measured data. A controller 100 controls a pressing force F, a rotating speed ω and a moving speed V of a dresser 72 so as to flatly dress the pad 34a based on the data of the obtained surface shape, and dresses the pad 34a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wafer polishing apparatus, and more particularly, to a wafer polishing apparatus for polishing a wafer by a chemical mechanical polishing (CMP) method.

[0002]

2. Description of the Related Art In recent years, fine processing of IC has been advanced, and an IC pattern is formed over multiple layers. However, it is inevitable that a certain degree of unevenness occurs on the surface of the layer on which the pattern is formed. Conventionally, the pattern of the next layer has been formed as it is, but as the number of layers increases, the unevenness of the surface becomes remarkable, making it difficult to form a good pattern. Further, the depth of focus of the exposure apparatus has become shallow due to the miniaturization of the pattern width, and it has been difficult to transfer a good pattern due to slight irregularities on the surface. Therefore, in recent years, after a pattern is formed, the surface of a layer is polished and flattened, and then a pattern of the next layer is formed. As described above, a wafer polishing apparatus (CMP apparatus) using a chemical mechanical polishing (CMP) is used to polish and flatten the wafer during the process of forming an IC pattern.

A CMP apparatus is generally composed of a polishing table for polishing a wafer and a polishing head for holding the wafer. The wafer held by the polishing head is pressed against the polishing table, and the wafer, the polishing table and The wafer is polished by rotating both of them while supplying an abrasive (slurry) therebetween.

Here, a polishing pad is attached to the surface of a polishing platen for polishing the wafer, and the wafer is
Polishing is performed by pressing against the polishing pad. But,
Since the polishing amount of the polishing pad decreases due to clogging of the surface, the CMP apparatus dresses the polishing pad every time one wafer is polished or during polishing of the wafer.

Conventionally, in the dressing of the CMP apparatus, the entire polishing pad is dressed at once by rotating a dresser having a diameter larger than the polishing use area on the polishing pad while rotating the dresser. Or,
Dressing is performed by pressing a relatively small-diameter dresser against a polishing pad while rotating the dresser and moving the dresser along the surface of the polishing pad.

The surface of the polishing pad is polished little by little by dressing, so that the surface shape is deformed and the flatness gradually deteriorates. When the wafer is polished using such a polishing pad, there is a disadvantage that the wafer cannot be flattened with high accuracy.

Therefore, conventionally, when dressing is performed, an operator measures the straightness of the surface of the polishing pad with a straightness measuring device, and checks the polishing amount from the measurement result to adjust the dressing. Alternatively, in the case of a polishing pad with a groove, an operator measures the depth of the groove, checks the polishing amount from the measurement result, and adjusts the dressing.

[0008]

However, the conventional method of manually measuring the straightness of the polishing pad by an operator has the disadvantage that the measuring operation requires a great deal of time and is inefficient. In the method of measuring the depth of the groove, accurate measurement cannot be performed, and it is difficult to dress the polishing pad flat.

The present invention has been made in view of such circumstances, and a wafer polishing apparatus capable of automatically measuring the surface shape of a polishing pad and automatically dressing the polishing pad flat based on the measurement result. The purpose is to provide.

[0010]

According to the present invention, in order to achieve the above object, a wafer held by a polishing head is pressed against a polishing pad affixed to the surface of a rotating polishing plate while rotating the wafer. In a wafer polishing apparatus for polishing, a moving means for moving the polishing head along the surface of the polishing platen, and a measurement provided on the polishing head for measuring a distance from a predetermined reference point to the surface of the polishing head. Means, while measuring the distance from the reference point to the surface of the polishing head by the measuring means, by moving the polishing head in the radial direction of the polishing platen, the surface shape of the polishing pad The present invention provides a wafer polishing apparatus characterized by measuring the following.

According to the present invention, by moving the polishing head in the radial direction of the polishing plate while measuring the distance from a predetermined reference point to the surface of the polishing head by the measuring means,
Measure the surface shape of the polishing pad.

According to the present invention, in order to achieve the above object, the measuring means comprises a stylus provided in contact with a surface of the polishing platen and movably provided in a direction perpendicular to the surface. A moving amount measuring means for measuring the distance based on a moving amount of the stylus.
And a wafer polishing apparatus according to (1).

According to the present invention, the polishing head is moved along the surface of the polishing plate while the stylus is in contact with the polishing pad. Measure the uneven shape of the pad surface.

According to another aspect of the present invention, there is provided a wafer polishing apparatus, comprising: a dresser for rotating the polishing pad to dress the polishing pad; and a dresser for dressing the polishing pad. Dresser moving means for moving along the surface of the, based on the measurement result of the measuring means, so that the polishing pad is dressed flat, control means for controlling the drive of the dresser and the dresser moving means, The wafer polishing apparatus according to claim 1 or 2, further comprising:

According to the present invention, the control means controls the driving of the dresser and the dresser moving means so that the polishing pad is dressed flat based on the measurement information of the surface shape of the polishing pad.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a wafer polishing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a plan view showing an embodiment of a wafer polishing apparatus according to the present invention. As shown in FIG. 1, the wafer polishing apparatus 10 of the present embodiment includes an indexer section 12, a transport section 14, a polishing section 16, and a cleaning section 18.

The indexer section 12 supplies the wafer W before polishing and collects the wafer W after polishing. The indexer unit 12 includes a cassette rack 20 and an index robot 22.

In the cassette rack 20, four cassettes 24 each storing a large number of wafers W are set in parallel.

The indexing robot 22 is provided with two pivotable and bendable arms, and the arrow Y in FIG.
It is provided movably along the direction. The index robot 22 takes out the wafer W to be polished from the cassette 24 and transports the wafer W to the transport unit 14.
The cleaned wafer W is received from the cleaning unit 18 and stored in the cassette 24.

The transfer section 14 transfers the wafer W.
The transfer section 14 includes a first aligner 26, a transfer robot 30, and an unload cassette 32.

The first aligner 26 performs centering and thickness measurement of the wafer W supplied to the polishing section 16. Also,
The thickness of the wafer W is measured as needed.

The transfer robot 30 is provided with a load arm 30A and an unload arm 30B that can be bent and turned freely, and is provided so as to be movable along the arrow X direction in FIG. Here, load arm 3
0A is used for transporting the wafer W before polishing, and the wafer W before polishing is transferred to the indexing robot 22 of the indexer unit 12 by a pad (not shown) provided at the tip.
And transported to the first aligner 26. And
Wafer W centered by the first aligner 26
Is transported to the polishing section 16. On the other hand, the unloading arm 30 </ b> B is used for transporting the polished wafer W, and receives the polished wafer W from the polishing unit 16 by a pad (not shown) provided at the tip thereof, and transports it to the cleaning unit 18.

The unload cassette 32 is used to temporarily store polished wafers.
While the operation of Step 8 is stopped, the polished wafer W is transferred to the transfer robot 30 and temporarily stored therein.

The polishing section 16 polishes the wafer. As shown in FIGS. 1 and 2, the polishing section 16 includes polishing plates 34A, 34B, 34C, dressing devices 35A,
5B, 35C, transport units 36A, 36B, slurry supply nozzles 37A, 37B, 37C, polishing head 38A,
38B, polishing head moving devices 39A and 39B, pad shape measuring devices 40A and 40B and carrier cleaning unit 4
1A and 41B.

The polishing platens 34A, 34B and 34C are formed in a disk shape, and three units are horizontally disposed at a predetermined interval. Polishing pads 34a, 34b, 34c are provided on the upper surfaces of the respective polishing platens 34A, 34B, 34C.
Are attached, and the polishing pads 34a, 34b, 3
Slurry is supplied onto slurry 4c from slurry supply nozzles 37A, 37B, 37C. In addition, each polishing platen 34A, 34
B and 34C are driven by a motor (not shown) to rotate,
The wafer W is polished by pressing the wafer W against the rotating polishing plates 34A, 34B, and 34C.

Here, the three polishing plates 34A, 34
The center polishing table 34C of B and 34C is set to have polishing characteristics different from those of the left and right two polishing tables 34A and 34B. Basically, the polishing characteristics vary depending on the type of slurry to be supplied, but also by changing the number of revolutions of the polishing head and the number of revolutions of the polishing platen, and also by changing the pressing force of the polishing head and the material of the polishing pad. Can also be changed.

Dressing devices 35A, 35B, 35C
Is arranged near each of the polishing plates 34A, 34B, 34C, and dresses the polishing pads 34a, 34b, 34c attached to each of the polishing plates 34A, 34B, 34C.
The dressing devices 35A, 35B, 35C are shown in FIG.
As shown in the figure, the arm 70 and a dresser 72 provided at the tip of the arm 70.

The arm 70 is provided so as to be pivotable in a horizontal direction about a pivot shaft 71 provided at a base end thereof and vertically movable in a vertical direction. The arm 70 is driven by an arm turning device (not shown) to turn in the horizontal direction, and is driven by an arm lifting device (not shown) to move up and down in the vertical direction.

The dresser 72 is formed in a disk shape, and is rotatably provided at the lower end of the tip of the arm 70. The dresser 72 is driven and rotated by a dresser driving motor (not shown) built in the distal end of the arm 70.

The dressing devices 35A, 35B and 35C configured as described above are used for rotating the polishing pad 34.
a, 34b, and 34c, the rotating dresser 72 is pressed against the polishing platens 34A, 34B, and 34.
By moving along the upper surface of C, the polishing pad 3
4a, 34b and 34c are dressed.

Here, the dresser 72 moves horizontally along the upper surfaces of the polishing plates 34A, 34B, 34C by turning the arm 70 by an arm turning device (not shown). The arm 70 is moved up and down by a not-shown arm elevating device so as to move up and down. The arm 70 is connected to the polishing pads 34a, 3a
By descending toward 4b, 34c, the dresser 72 is pressed against the polishing pads 34a, 34b, 34c.

The driving of the arm turning device and the arm lifting / lowering device is controlled by a control device 100, and the arm 70 is controlled based on an operation signal output from the control device 100.
Turn and move up and down. The driving of the dresser driving motor is similarly controlled by the control device 100, and the dresser 72 is rotated based on an operation signal output from the control device 100. That is, the controller 100 controls the horizontal moving speed V, the pressing force F applied to the polishing pads 34a, 34b, and 34c, and the rotation speed ω of the dresser 72.

Normally, the dresser 72 is located at the standby position as shown by a two-dot broken line in FIG. 3 so as not to contact the polishing heads 38A and 38B during polishing.

The dresser 72 moves along an arc centered on the turning shaft 71 as the arm 70 turns. At this time, the dresser 72 is
a, 34b, the center O _A of 34c, O _B, moves on a circular arc passing through the O _C.

The transport units 36A and 36B are provided between the polishing plates 34A and 34C and between the polishing plates 34B and 34C. The transport units 36A and 36B include load pots 42A and 42B and unload pots 44A and 44B, respectively. Road pot 42A,
42B and the unload pots 44A and 44B are installed coaxially in the vertical direction, and each is independently shown by an arrow Y-Y in FIG.
Move in the direction.

Here, the load pots 42A and 42B are
Used for transporting the wafer W before polishing, the wafer W before polishing is received from the loading arm 30A of the transfer robot 30 at the predetermined receiving positions S _A and S _B and moved to the predetermined transfer positions T _A and T _B. Then, the wafer W before polishing is transferred to the polishing heads 38A and 38B. On the other hand, the unload pots 44A and 44B
, And receives the polished wafer W from the polishing heads 38A, 38B at predetermined delivery positions T _A , T _B , moves to the predetermined receiving positions S _A , S _B , and transfers the polished wafer W is transferred to the unloading arm 30B of the transfer robot 30.

Two polishing heads 38A and 38B are provided, and polishing head moving devices 39A and 39B described later are provided.
Are provided so as to be movable along the arrow X direction in FIG.

FIG. 4 is a longitudinal sectional view showing the structure of the polishing head 38A. As shown in FIG.
Head body 45, carrier 46, retainer ring 4
8, a guide ring 50, a carrier airbag 52, and a retainer ring airbag 54.

The head body 45 is formed in a disk shape, and a rotating shaft 56 is connected to the center of the upper surface. Rotary axis 5
6 is rotatably and vertically movable supported by a drive unit 57 (see FIG. 2). The drive unit 6 is driven by a motor (not shown) provided in the drive unit 57 to rotate, and is also driven by a lifting mechanism (not shown). Go up and down.

The carrier 46 is disposed below the head main body 45 and is provided so as to be vertically movable. The carrier 46 is formed in a disk shape, and a plurality of air outlets 58 and a plurality of air suction ports 60 are formed on a lower surface thereof. Compressed air is blown from the air outlet 58, and the wafer W is pressed against the polishing platen by the air pressure of the compressed air blown from the air outlet 58. On the other hand, the air suction port 6
Air is sucked from 0, and the air is sucked from the air suction port 60, whereby the wafer W is suction-held on the lower surface of the carrier 46.

The retainer ring 48 is formed in a cylindrical shape and is arranged on the outer periphery of the carrier 46. The retainer ring 48 is pressed against the polishing pad with a predetermined pressure, surrounds the periphery of the wafer W, and prevents the wafer W from jumping out. At the same time, the state of the inner polishing pad is made uniform to prevent uneven polishing of the wafer W.

The guide ring 50 is formed in a cylindrical shape, and is arranged on the outer periphery of the retainer ring 48. The guide ring 50 is integrally fixed to the outer periphery of the lower surface of the head main body 45 and moves up and down together with the head main body 45. When the head body 45 is raised, the retainer ring 4
The retainer ring 48 is lifted by engaging with a flange portion formed on the outer periphery of 8. Also, retainer ring 4
When the guide ring 8 is lifted by the guide ring 50, it engages with a flange formed on the outer peripheral portion of the carrier 46 to lift the carrier 46.

When the retainer ring 48 is pressed against the polishing pad, the retainer ring 48 is disengaged from the guide ring 50 and is supported vertically. Similarly, when the carrier 46 is pressed against the polishing pad via the wafer W, the engagement with the retainer ring 48 is released, and the carrier 46 is supported so as to be vertically movable.

The carrier airbag 52 is provided between the head body 45 and the carrier 46. The carrier airbag 52 is formed of a rubber sheet 62 </ b> A disposed on the lower surface of the head main body 45, and is inflated by supplying compressed air from a central air outlet 64 formed on the lower surface of the head main body 45. The compressed air of a predetermined pressure is supplied to the carrier airbag 52,
The carrier 46 is pressed downward at a predetermined pressure, and the wafer W is pressed by the carrier 46 to the polishing pad via the air layer.

The retainer ring airbag 54 is disposed between the head body 45 and the retainer ring 48. The retainer ring airbag 54 is formed of a rubber sheet 62B disposed on the lower surface of the head body 45, and is inflated by supplying compressed air from an outer air outlet 66 formed on the lower surface of the head body 45. . By supplying compressed air at a predetermined pressure to the retainer ring airbag 54, the retainer ring 4
8 is pressed downward at a predetermined pressure and pressed against the polishing pad at a predetermined pressure.

The polishing head 38A is constructed as described above. The wafer W held by the polishing head 38A is pressed against the polishing pad 34a on the polishing table 34A to rotate the polishing table 34A and the polishing head 38A. While supplying the slurry onto the polishing pad 34a, the wafer W is polished. Polishing head 34 on the other side
B is similarly configured.

The polishing heads 38A and 38B are
By moving in the direction of arrow X in FIG. 1 respectively, predetermined delivery positions T _A , T _B and predetermined polishing positions P _A , P _B , P
Move between _C. More specifically, the polishing head 38A of the right side in the figure, between a predetermined polishing position P _A which is set on a predetermined transfer position T _A and the polishing surface plate 34A of the transport unit 36A, and the conveying unit 36A to the move between the predetermined polishing position P _B that is set on a predetermined transfer position T _a and the polishing surface plate 34B. The polishing head 38B on the left side in the figure, between a predetermined polishing position P _B that is set on a predetermined delivery position T _B and the polishing surface plate 34B of the conveying unit 36B, and a predetermined transfer conveyance unit 36B position moves between the predetermined polishing position T _C set on a polishing platen 34C and T _B.

The polishing head moving devices 39A and 39B reciprocate the polishing heads 38A and 38B horizontally along the arrow X direction in FIGS.

As shown in FIGS. 2 and 5, a pair of guide rails 76, 76 are provided on the ceiling frame 74 of the polishing section 16.
Are placed horizontally at regular intervals (each polishing platen 34A, 34
B, 34C). On the guide rails 76, 76, movable tables 78A, 78B are slidably supported via guide blocks (not shown).

A screw rod 80 is laid on the ceiling frame 74 in parallel with the guide rail 76, and a pair of nuts 82A and 82B are screwed to the screw rod 80. Gear teeth are integrally formed on the outer periphery of the nuts 82A and 82B, and drive teeth 84A and 8
4B is engaged. The drive gears 84A and 84B are connected to output shafts of polishing head moving motors 86A and 86B installed on the moving tables 78A and 78B, respectively.
The polishing head moving motors 86A and 86B are driven to rotate.

Here, the polishing head moving motor 86
The driving of A and 86B is controlled by the control device 100, and the polishing head moving motors 86A and 86B are driven based on the driving signal output from the control device 100. Then, the polishing head moving motor 86A,
When the drive gear 86A is driven to rotate the drive gears 84A and 84B, the rotation is transmitted to the nuts 82A and 82B, and the movable tables 78A and 78 are moved together with the nuts 82A and 82B.
B moves along the guide rails 76,76.

The polishing head moving motor 86
An encoder (not shown) is attached to A and 86B. The encoder detects the number of rotations of the motor and outputs the detected value to control device 100. The control device 100
The moving tables 78A, 78 based on the detected values of the encoder
The position of B, that is, the positions of the polishing heads 38A and 38B is detected.

The driving units 57, 57 for driving the polishing heads 38A, 38B are installed on the moving tables 78A, 78B. Therefore, the polishing heads 38A, 38B
Moves horizontally along the X direction in FIG. 2 by moving the moving tables 78A and 78B.

The pad shape measuring devices 40A and 40B measure the surface shapes of the polishing pads 34a, 34b and 34c attached to the polishing plates 34A, 34B and 34C. The pad shape measuring devices 40A and 40B are provided with a displacement measuring device 88.
A and 88B, and a control device 100 for obtaining the surface shapes of the polishing pads 34a, 34b and 34c based on the measurement results of the displacement measuring devices 88A and 88B.

As shown in FIG. 4, the displacement measuring devices 88A and 88B are provided on the polishing heads 38A and 38B.
A guide rail 92 is attached to the head main body 45 of the polishing heads 38A and 38B via a bracket 90. The guide rails 92 are polished platens 34A, 34B,
The guide 94 is provided perpendicular to the upper surface of the guide rail 34C, and a slider 94 is slidably provided on the guide rail. The slider 94 is driven up and down by an elevating means (not shown), and a displacement measuring device main body 96 is provided on the slider 94.

The polishing table 34 is attached to the displacement measuring device main body 96.
A stylus 98 that moves vertically with respect to the upper surfaces of A, 34B, and 34C is provided, and the amount of displacement of the stylus 98 is measured by a detector (for example, an operation transformer) incorporated in the displacement measuring device main body 96. Is detected. Then, this detected value is output to control device 100.

The control device 100 includes displacement measuring devices 88A, 8
The surface shapes of the polishing pads 34a, 34b, 34c are measured based on the position information of 8B and the displacement information at that position. That is, the control device 100 controls the displacement measuring device 8
8A and 88B are attached to the polishing pads 34a and 3b.
4b and 34c in contact with the displacement measuring devices 88A and 88
8B is moved horizontally, and the styluses 98, 98 at each position are moved.
Polishing pads 34a, 34b, 34 based on displacement information of
The shape of the surface of c is measured. Specifically, the measurement is performed as follows.

First, the control device 100 drives the polishing head moving motors 86A and 86B to drive the displacement measuring device 88.
A, 88B stylus 98, 98 with polishing pad 34a, 34
b, 34c. Next, the displacement measuring device main body 96 is lowered to a predetermined measurement position at that position, and the stylus 9 is moved.
8 and 98 are brought into contact with the polishing pads 34a, 34b and 34c. Next, the polishing head moving motors 86A and 86B are driven to move the displacement measuring devices 88A and 88B to the polishing pad 34.
a, 34b and 34c are moved horizontally along the radial direction. Then, the stylus 98 at each position at this time
Is measured by the displacement measuring devices 88A and 88B. The detected displacement information is recorded in a memory (not shown) built in the control device 100 together with the corresponding position information.
The displacement information at each point is directly transmitted to the polishing pad 34.
a, 34b, and 34c indicate the state of the irregularities on the surface.
The surface shapes of 4a, 34b, and 34c are obtained.

The displacement measuring device main body 96 of the displacement measuring devices 88A and 88B is usually located at the standby position at the upper end of the guide rail, and moves to the measuring position only at the time of measurement. Therefore, usually, the styluses 98, 98 are attached to the polishing pads 34a, 3a.
There is no contact with 4b and 34c.

The carrier cleaning units 41A and 41B are
There are two units, each of which has a transport unit 36A, 3
6B at predetermined delivery positions T _A and T _B.
The carrier cleaning units 41A and 41B clean the carriers of the polishing heads 38A and 38B.

The cleaning unit 18 cleans the polished wafer. The cleaning unit 18 includes a cleaning device 68A and a drying device 68B. The wafer W polished by the polishing unit 16 is transported to the cleaning unit 18 by the transfer robot 30, and is roughly cleaned and finely cleaned by the cleaning device 68A of the cleaning unit 18 and then dried by the drying device 68B. The dried wafer W is taken out of the drying device 68B by the indexing robot 22 of the indexer unit 12 and stored in a predetermined position of the cassette 24 set in the cassette rack 20.

The wafer polishing apparatus 10 according to the present embodiment is configured as described above.

First, a method of processing a wafer W in the wafer polishing apparatus 10 will be described.

First, the wafer W stored in the cassette 24 is taken out by the index robot 22,
It is transported to the first aligner 26. Then, centering and thickness measurement are performed by the first aligner 26. The centered wafer W is transferred to the transfer robot 30.
Is taken out of the first aligner 26 by the loading arm 30A and transported to the polishing section 16.

[0066] On the other hand, in the polishing unit 16, passed preloaded pot 42A has been waiting in a predetermined receiving position S _A, the wafer W from the load arm 30A to a load pot 42A located in the delivery position S _A receives . Loading pot 42A to the wafer W is transferred is moved forward to to a predetermined transfer position T _A. Above the transfer position T _A, and advance the polishing head 38A is waiting,
The wafer W is delivered to the polishing head 38A from the load pot 42A.

The polishing head 38 to which the wafer W has been delivered
A sucks and holds the wafer W with the carrier 46,
Moves to a predetermined polishing position P _A. Then, the suction is released at that position, and the wafer W is mounted on the polishing pad 34a to polish the wafer W. In the polishing, while the wafer W is pressed against the polishing pad 38a by the carrier 46, both the polishing table 34A and the polishing head 38A are rotated, and the slurry supply nozzle 37A is placed on the rotating polishing pad 34a.
The slurry is supplied from and polished.

After the polishing is completed, the wafer W is sucked and held by the carrier 46 again and collected from the polishing platen 34A. Thereafter, in case of polishing a further wafer W by changing the polishing characteristics, polishing head 38A is moved to the polishing position P _C of the intact central polishing platen 34C. Then, the second polishing with the polishing characteristics changed is performed on the central polishing table 34C. On the other hand, if the finish polishing in only once, the polishing head 38A is moved to a predetermined transfer position T _A. Then, pass the wafer W to unload pot 44A, which was previously located in the transfer position T _A.

[0069] Also in the case of performing the second time of the polishing at the center of the polishing platen 34C, after completion of polishing, the unload pot 44A polishing head 38A is moved to the transfer position T _A from the polishing position P _C Deliver the wafer W.

[0070] transfer position T _A unload pot 44A which the wafer W after polishing has been passed, the movement retreated to a predetermined transfer position S _A. Then, the wafer W by the unloading arm 30B of the transfer robot 30 from the unload pot 44A located in the delivery position S _A is extracted, is conveyed to the cleaning section 18.

The wafer W transferred to the cleaning unit 18 is roughly cleaned and finely cleaned by the cleaning device 68A, and then dried by the drying device 6A.
Dry at 8B. Then, the wafer W dried by the drying device 68B is taken out from the drying device 68B by the indexing robot 22 of the indexer unit 12, and
The cassette 24 is stored at a predetermined position on the cassette 24 set on the cassette rack 20.

The polishing of one wafer W is completed through a series of steps described above. In the above example, for simplicity of explanation, an example in which only one of the two polishing heads 38A is used to polish the wafer W has been described. However, in order to perform efficient processing. Then, the wafer W is polished using the other polishing head 38A. That is, one of the polishing heads 38A is positioned at the center of the polishing platen 34C.
While the wafer W is being polished by the other polishing head 3
8B polishes the wafer W with the left polishing platen 34B, and while the other polishing head 38B polishes the wafer W with the central polishing platen 34C, one polishing head 34A is polished with the right polishing platen 34A. Polish the wafer with.

Next, the wafer polishing apparatus 1 of the present embodiment
A method of dressing the polishing pads 34a, 34b, 34c by using a zero will be described. Here, a case where the polishing pad 34a is dressed will be described.

The dressing is performed every time one wafer W is polished or during the polishing of the wafer W.

First, the control device 100 drives the polishing head moving motor 86A to drive the stylus 9 of the displacement measuring device 88A.
8 is positioned at the center O _A of the polishing pad 34a.

Next, the displacement measuring device main body 96 is lowered to a predetermined measuring position at that position. As a result, the stylus 98 comes into contact with the polishing pad 34a.

Next, by driving the polishing head moving motor 86A to move the polishing head 38A in the horizontal direction, the displacement measuring device 88A is moved horizontally along the radial direction of the polishing pad 34a.

The displacement measuring device 88 A outputs the displacement information of the stylus 98 at each point moved to the control device 100.
The control device 100 records the displacement information of the stylus 98 together with the position information in a built-in memory.

When the stylus 98 reaches the outer periphery of the polishing pad 34a, the control device 100 stops the movement of the polishing head 38A. That is, the polishing head driving motor 8
The drive of 6A is stopped. Then, the displacement measuring device main body 96
Is raised to a predetermined standby position.

Thus, the measurement of the surface shape of the polishing pad 34a is completed. After the measurement is completed, the polishing head 38A
Waiting above the transfer position T _A. The control device 100 obtains the surface shape of the polishing pad 34a based on the measured displacement information of the stylus 98 and the corresponding position information.
That is, since the stylus 98 moves while being in contact with the surface of the polishing pad 34a, the displacement directly reflects the unevenness of the polishing pad surface. Therefore, the change in the displacement directly represents the unevenness state of the polishing pad surface.

[0081] Also, the stylus 98, since is moved along the radial direction of the polishing pad 34a from the center O _A of the polishing pad 34a, the information of the obtained displacement, irregularities of the polishing pad 34a in a certain cross-section Is grasped. Here, since the polishing pad 34a is dressed while rotating at a constant speed, the amount of wear in the circumferential direction can be regarded as constant. Accordingly, the unevenness state of the entire surface of the polishing pad 34a can be obtained from the obtained displacement information of the stylus 98.

For example, as shown in FIG. 6A, the obtained displacement information of the stylus 98 is stored in the center O of the polishing pad 34a.
_{When the} size gradually increases from _A to the outer peripheral portion, it indicates that the amount of wear increases toward the central portion of the polishing pad 34a as shown in FIG.
(B), the case that is a constant toward the outer periphery from the center O _A of the polishing pad 34a is drawing (b
As shown in '), the wear amount of the polishing pad 34a is constant. Further, as shown in FIG. 6C, the obtained displacement information of the stylus 98 is transmitted to the polishing pad 34a.
If the center O _A gradually decreases toward the outer periphery, as shown in FIG. (C'), polishing pad 34
It shows that the amount of wear is large toward the outer peripheral portion of a.

As described above, the control device 100 obtains the surface shape of the polishing pad 34a based on the measured displacement information of the stylus 98 and the corresponding positional information. Then, based on the obtained surface shape data, the polishing pad 34a
Dressing device 3 so that the surface of
The dressing is performed by controlling the driving of 5A. More specifically, dressing is performed so that the polishing pad 34a is flat by controlling the moving speed V, the pressing force F, and the rotation speed ω of the dresser 72.

Here, for example, a case is considered in which the pressing force F and the rotation speed ω of the dresser 72 are kept constant, and only the moving speed V is controlled to dress the polishing pad 34a. When the moving speed V is constant, the dress amount per unit area (dressing time) increases as the dresser 72 approaches the center of the polishing pad 34a, so that the polishing pad 34a is as shown in FIG. Then, it is dressed so as to be inclined toward the center. If the moving speed is gradually increased from the outer periphery toward the center, the dressing is performed so as to be inclined toward the outer periphery, as shown in FIG. Therefore, by controlling only the moving speed V, the polishing pad 34a
6 is controlled by controlling the moving speed V of the dresser 72 so that the dress amount per unit area (dress time) is constant at any point.
As shown in (b '), the polishing pad 34a can be dressed flat.

As described above, by controlling the moving speed V of the dresser 72, the amount of dress per unit area (dressing time) can be controlled.
From the obtained data on the surface shape of the polishing pad 34a, a dresser 7 is used so that the polishing pad 34a becomes flat.
The polishing speed of the polishing pad 34a is polished by controlling the moving speed V of Step 2.

For example, when dressing the polishing pad 34a by controlling only the pressing force F while keeping the moving speed V and the rotating speed ω of the dresser 72 constant, depending on the magnitude of the pressing force F, the polishing pad 34a Can be controlled, the control device 100 controls the pressing force F of the dresser 72 from the obtained data of the surface shape of the polishing pad 34a so that the polishing pad 34a is flat,
The polishing pad 34a can be polished.

Further, when the polishing pad 34a is dressed by controlling only the rotation speed ω while keeping the moving speed V and the pressing force F of the dresser 72 constant, the dressing of the polishing pad 34a depends on the level of the rotation speed ω. Since the amount can be controlled, the control device 100 controls the rotation speed ω of the dresser 72 based on the obtained data on the surface shape of the polishing pad 34a so that the polishing pad 34a becomes flat, thereby polishing the polishing pad 34a. You can also.

The controller 100 does not individually control the moving speed V, the pressing force F, and the rotational speed ω of the dresser 72, but controls them in a complex manner to dress the polishing pad 34a so that the polishing pad 34a becomes flat. You can also. That is, the control device 100 most efficiently controls the polishing pad 3
Dressing is performed by appropriately selecting a combination capable of dressing 4a flat.

As described above, in the wafer polishing apparatus 10 of the present embodiment, the surface shapes of the polishing pads 34a, 34b, 34c are measured, and the polishing pad 3 is determined based on the measurement results.
Since dressing is performed so that 4a, 34b and 34c are flat, polishing pads 34a, 34b and 34 are always used.
c can be kept flat. As a result, the wafer can always be polished with stable accuracy.

The polishing pads 34a, 34b, 3
Since the measurement means for measuring the surface shape of 4c is installed in the wafer polishing apparatus 10, and the measurement is automatically performed, it is not necessary for the operator to separately perform the measurement, and the highly accurate measurement can be easily performed.

The measuring means includes the polishing heads 38A,
8B, it is not necessary to provide a separate moving means, and the entire apparatus can be compactly assembled.

In the above embodiment, only the case where the polishing pad 34a is dressed is described. However, the other polishing pads 34b and 34c can be dressed in the same manner.

The dressing may be performed each time one wafer W is polished, or
May be carried out during the polishing.

In the present embodiment, the polishing pad 34
As a method of measuring the surface shape of a, 34b, 34c,
The method employs a method of measuring the amount of displacement of the stylus 98 brought into contact with the surfaces of the polishing pads 34a, 34b, 34c, but the polishing head moves parallel to the surfaces of the polishing platens 34A, 34B, 34C. Any means capable of measuring the distance from a certain point (reference point) of 38A, 38B to the surface of the polishing pad 34a, 34b, 34c is not limited thereto. For example, a non-contact ultrasonic sensor or An optical sensor or the like may be used.

Further, in the present embodiment, the irregularities on one specific cross section of the polishing pads 34a, 34b, 34c are measured by one measurement. For example, the measurement may be performed a plurality of times at predetermined intervals. It may be. This allows
The unevenness of the polishing pad surface at a plurality of cross sections can be measured, and the unevenness of the polishing pad surface can be grasped more accurately.

[0096]

As described above, according to the present invention,
Since the surface shape of the polishing pad is automatically measured by the measuring means provided on the polishing head, the surface shape of the polishing pad can be easily and accurately measured without separately measuring by the measuring means. Also, since the polishing pad is dressed so as to be flat based on the measurement result,
The polishing pad can always maintain a flat state, and can constantly polish the wafer with stable accuracy.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a wafer polishing apparatus according to the present invention.

FIG. 2 is a front view showing a configuration of a polishing unit.

FIG. 3 is a plan view showing a configuration of a dressing device.

FIG. 4 is a longitudinal sectional view showing a configuration of a polishing head.

FIG. 5 is a top view showing a configuration of a polishing unit.

FIG. 6 is an explanatory diagram of a dressing method.

[Explanation of symbols]

10: Wafer polishing apparatus, 12: Indexer unit, 14
... Conveying unit, 16 ... Polishing unit, 18 ... Washing unit, 20 ... Cassette rack, 22 ... Index robot, 24 ... Cassette, 26 ... First aligner, 30 ... Transfer robot, 30A ... Load arm, 30B ... Unload Arm, 32 ... unload cassette, 34A, 34B,
34C: Polishing surface plate, 34a, 34b, 34c: Polishing pad, 35A, 35B, 35C: Dressing device, 36
A, 36B: transport unit, 37A, 37B, 37C ...
Slurry supply nozzle, 38A, 38B ... polishing head, 39
A, 39B: Polishing head moving device, 40A, 40B: Pad shape measuring device, 41A, 41B: Carrier cleaning unit, 42A, 42B: Load pot, 44A, 44B
... unload pot, 45 ... head body, 46 ... carrier, 48 ... retainer ring, 50 ... guide ring, 5
2 ... Airbag for carrier, 54 ... Airbag for retainer ring, 56 ... Rotating shaft, 57 ... Drive unit, 58
... air outlet, 60 ... air suction port, 62A, 62B ... rubber sheet, 64 ... central air outlet, 66 ... outer peripheral air outlet, 68A ... cleaning device, 68B ... drying device, 70 ... arm, 72 ... dresser, 74: ceiling frame, 76: guide rail, 78A, 78B: movable table, 80: screw rod, 8
2A, 82B: nut, 84A, 84B: drive gear, 8
6A, 86B: Polishing head moving motor, 88A, 88
B ... displacement meter, 90 ... Bracket, 92 ... guide rail, 94 ... slider, 96 ... displacement measuring instrument body, 98 ... probe, 100 ... control unit, W ... wafer, O _A, O _B, O
_C : Center of polishing platen, S _A , S _B … Receiving position, T _A , T
_B ... delivery _{position, P A, P B, P} C ... polishing position

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B24B 53/02 B24B 53/02 F-term (Reference) 3C034 AA08 AA13 BB92 CA09 DD05 3C047 AA02 AA34 3C058 AA07 AA19 AC02 BC02 DA12 DA17

Claims (3)

[Claims] 1. A wafer polishing apparatus for polishing a wafer by rotating and pressing a wafer held by a polishing head against a polishing pad stuck on a surface of a rotating polishing table, wherein the polishing head is mounted on the polishing pad. Moving means for moving along the surface of the board; andmeasuring means provided on the polishing head, for measuring a distance from a predetermined reference point to the surface of the polishing head, comprising: A wafer polishing apparatus, wherein a surface shape of the polishing pad is measured by moving the polishing head in a radial direction of the polishing platen while measuring a distance to a surface of the polishing head. 2. The stylus provided in contact with a surface of the polishing platen and movably provided in a direction perpendicular to the surface, wherein the measuring means comprises: 2. The wafer polishing apparatus according to claim 1, further comprising a movement amount measuring means for measuring a distance. 3. A dresser, which is pressed against the polishing pad while rotating, to dress the polishing pad, and a dresser moving means for moving the dresser along the surface of the polishing platen. And control means for controlling the driving of the dresser and the dresser moving means so that the polishing pad is dressed flat based on the measurement result of the measuring means. Item 3. The wafer polishing apparatus according to item 1 or 2.