JP2000153450A - Flat surface polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a favorable flat surface precision in a flat surface polishing device using a polishing tool of a relatively small surface compared to a surface of a workpiece to be polished. SOLUTION: A silicon wafer 1 is held on an upper surface of a turn table 2. A polishing head 7 is disposed above the turn table 2, and a polishing cloth 6 is installed on a lover surface of it. The polishing head 7 is installed on a tip part of an arm, and it makes reciprocating motion in a parallel surface to a surface to be polished. A pair of polishing agent supplying nozzles 31a, 31b are disposed along an outer circumference of the polishing head 7, and the respective nozzles 31a, 31b are connected to respective pumps 33a, 33b. On a column 12 supporting the arm 11, a turning angle detecting angle sensor 43 is installed. A control device 41 receives an output signal from the angle sensor 43 to separately control supply quantity of polishing agent from the nozzles 31, 31b in accordance with a turning angle of the arm 11 based on preset instructions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat surface polishing apparatus such as a CMP apparatus (Chemical Mechanical Polishing Machine) which uses a polishing tool having a smaller area than a surface to be polished of a workpiece. Related to the device.

[0002]

2. Description of the Related Art In recent years, as semiconductor circuits have been miniaturized and multilayered, the beam wavelength of an exposure apparatus used for pattern formation has been shortened, and the margin of depth of focus by photolithography has been gradually narrowed. . For this reason, a planarization technique for globally reducing steps on the surface of an interlayer insulating film or a metal film formed on a silicon substrate is becoming an indispensable technique for performing multilayer wiring. Therefore, as a method for globally and accurately planarizing the surface of a silicon wafer, a CMP (Chemical Mechanical) method is used.
cal Polishing).

[0003] In a CMP apparatus, generally, a slurry (hereinafter, referred to as a polishing machine) in which abrasive grains are mixed in pure water is provided between a polishing tool such as a polishing cloth or a grindstone and a surface to be polished of a workpiece such as a silicon wafer. The polishing tool and the workpiece are rotated while the polishing tool is pressed against the surface to be polished, and the workpiece is polished. When a grindstone is used as a polishing tool, a chemical solution or pure water may be used instead of the abrasive.

When a workpiece having a large area such as a large-diameter silicon wafer is polished, a polishing tool having a smaller area than a surface to be polished is used. Such a C
In the MP apparatus, the polishing tool is reciprocated within a plane parallel to the surface to be polished, and the entire surface of the surface to be polished is polished.

FIG. 9 shows an outline of such a CMP apparatus.

A silicon wafer 1 to be processed is provided on a top surface of a turntable 2 with a backing pad (not shown).
(Or held by vacuum suction or electrostatic suction). A polishing head 7 is arranged so as to face the upper surface of the turntable 2, and a polishing cloth 6 is attached to the lower surface of the polishing head 7 by bonding.

The polishing head 7 is fixed to a shaft of a motor 8, and a housing of the motor 8
And, it is attached to the distal end of the arm 11 via the linear motion guide 10. The motor 8 drives the polishing head 7 to rotate, and the air cylinder 9 moves the polishing head 7 in the vertical direction, and presses the polishing cloth 6 against the silicon wafer 1 during polishing. The arm 11 is a column 1
Oscillating motion is performed on a swivel path around 2, thereby reciprocating the polishing head 7 in a plane parallel to the surface to be polished.

A nozzle 4 for supplying an abrasive is arranged adjacent to the outer peripheral portion of the polishing head 7. This nozzle 4
The polishing agent is supplied between the surface to be polished and the polishing pad 6 by dropping the polishing agent 5 around the polishing head 7.

FIG. 10 shows a relative position between the surface to be polished of the silicon wafer 1 and the polishing head 7 (that is, a relative position with respect to the polishing cloth 6 mounted on the lower surface of the polishing head 7). The polishing head 7 moves on a turning orbit passing through the center of the silicon wafer 1.
The silicon wafer 1 reciprocates between one peripheral edge and the other peripheral edge.

At this time, depending on the relative position of the polishing head 7 with respect to the silicon wafer 1, the abrasive 5 dropped from the nozzle 4 to the periphery of the polishing head 7 causes the silicon wafer 1 to move as shown by a relative position C in FIG. With the rotation of 1, the polishing head 7 is carried in the direction opposite to the polishing head 7 and is not efficiently supplied between the polishing cloth 6 and the surface to be polished.

As described above, when the effective supply amount of the abrasive to the surface to be polished fluctuates depending on the relative position of the polishing head with respect to the workpiece (in the above example, the silicon wafer 1), the processing speed changes every moment. As a result, the planarity of the polished surface is reduced.

Further, since the supplied abrasive is not used effectively, an extra abrasive is required.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional planar polishing apparatus, and an object of the present invention is to reduce the size of a surface to be polished of a workpiece. It is an object of the present invention to provide a planar polishing apparatus which can realize good planar accuracy in a planar polishing apparatus using a polishing tool having a large area.

[0014]

According to the present invention, there is provided a planar polishing apparatus comprising: a turntable on which a flat workpiece is held on an upper surface; and a turntable opposed to the upper surface of the turntable.
A polishing tool having a smaller area than the surface to be polished of the workpiece is mounted. The polishing tool is pressed against the surface to be polished while rotating and driving the polishing tool, and a polishing head for polishing the surface to be polished, A moving mechanism for moving the polishing head in a plane parallel to the polishing head, a plurality of nozzles provided near the outer periphery of the polishing head and supplying an abrasive from the periphery of the polishing head to the surface to be polished. And a control device for individually controlling the supply amount of the abrasive from each of the nozzles according to a preset instruction according to the position of the polishing head with respect to the turntable.

[0015] Preferably, the control device selectively supplies the polishing agent from a nozzle located rearward of the plurality of nozzles in the rotation direction of the turntable with respect to the polishing head. At the same time, the supply amount of the abrasive from each nozzle is controlled according to the number of nozzles for supplying the abrasive.

In the above description, the term “abrasive” refers to not only a slurry in which fine abrasive grains are dispersed in pure water but also a water in which a chemical which reacts chemically with the surface to be polished to process the polished surface is dissolved. Alternatively, it also means a solvent or pure water.

The number of nozzles depends on the diameter of the polishing head, but is suitably about 2 to 4 nozzles.

According to the planar polishing apparatus of the present invention, in a planar polishing apparatus using a polishing tool having a smaller area than the surface to be polished of the workpiece, the relative position of the polishing head with respect to the turntable holding the workpiece. In accordance with the above, by controlling the presence / absence of the abrasive from the plurality of nozzles and the flow rate thereof as needed, an appropriate amount of the abrasive is supplied to the polishing head from an optimal position. be able to.

Thus, the supply amount of the abrasive to the surface to be polished is stabilized without being affected by the change in the relative position of the polishing head with respect to the turntable, so that the processing speed is stabilized. As a result, good planar accuracy can be achieved for the polished surface after polishing.

As described above, instead of a structure in which a plurality of nozzles are arranged and selectively used, a nozzle for supplying an abrasive to the surface to be polished is arranged near the outer periphery of the polishing head. In addition, this is configured so as to be able to move along the outer periphery of the polishing head, and according to a relative position of the polishing head with respect to the turntable, the position of the nozzle is controlled in accordance with a preset instruction to control the position of the nozzle. The device can also be configured.

Here, the control device controls the position of the nozzle, for example, such that the nozzle comes rearward of the polishing head in the rotation direction of the turntable with respect to the polishing head.

[0022]

FIG. 1 shows an example of a CMP apparatus according to the present invention.

In the figure, 1 is a silicon wafer (workpiece), 2 is a turntable, 6 is a polishing cloth (polishing tool),
7 is a polishing head, 11 is an arm (moving mechanism), 31a,
Reference numeral 31b denotes an abrasive supply nozzle, and reference numeral 41 denotes an abrasive supply control device (control device).

The silicon wafer 1 to be processed is held on the upper surface of the turntable 2 via a backing pad. A polishing head 7 is arranged so as to face the upper surface of the turntable 2, and a polishing cloth 6 is mounted on the lower surface of the polishing head 7.

The polishing head 7 is fixed to a shaft of a motor 8, and a housing of the motor 8 is provided with an air cylinder 9.
And, it is attached to the distal end of the arm 11 via the linear motion guide 10. The motor 8 drives the polishing head 7 to rotate, and the air cylinder 9 moves the polishing head 7 in the vertical direction, and presses the polishing cloth 6 against the silicon wafer 1 during polishing. The arm 11 is a column 1
The rocking motion is performed on a swirl path around 2. Along with this,
The polishing head 7 reciprocates between one peripheral edge and the other peripheral edge of the silicon wafer 1 in a plane parallel to the surface to be polished and on a turning orbit passing through the center of the silicon wafer 1. Do.

In this example, a pair of abrasive supply nozzles 31a and 31b are arranged along the outer periphery of the polishing head 7. These nozzles supply the polishing agent between the polishing surface of the silicon wafer 1 and the polishing pad 6 by dropping the polishing agent 5 around the polishing head 7.

Each of the nozzles 31a, 31b is connected to an individual abrasive supply pump 33a, 33b via an individual tube 32a, 32b. An angle sensor 43 for detecting the turning angle of the arm 11 is provided near the base of the column 12 for supporting and turning the arm 11.
Is attached. The abrasive supply control device 41 receives the output signal from the angle sensor 43 and individually controls each of the abrasive supply pumps 33a and 33b according to the turning angle of the arm 11 according to a preset instruction. Thus, the supply amount of the abrasive from each of the nozzles 31a and 31b is individually controlled.

Referring to FIG. 2, in this CMP apparatus,
An example of a method of controlling the supply of the polishing agent from each of the nozzles 31a and 31b according to the relative position of the polishing head 7 with respect to the silicon wafer 1 will be described. The arrows in the figure indicate the turntable 2 (that is, the silicon wafer 1).
And the rotation direction of the polishing head 7 (that is, the polishing cloth 6).

In FIG. 2, for example, when the polishing head 7 is at each of the positions A, B and C, the supply of the polishing agent from each nozzle is controlled as follows. That is, when the polishing head 7 is located at the position A (one peripheral portion) on the silicon wafer 1 and between the position A and the position B, the polishing head 7 is located on the rear side in the rotation direction of the turntable 2 with respect to the polishing head 7. Is selected, and an abrasive is supplied from the nozzle 31b. Similarly, when the polishing head 7 is located at the position C (the other peripheral portion) on the silicon wafer 1 and between the position C and the position B, the polishing head 7 is positioned rearward in the rotation direction of the turntable 2 with respect to the polishing head 7. The nozzle 31a on the side is selected, and the abrasive is supplied from the nozzle 31a. When the polishing head 7 is located at the position B (center portion) on the silicon wafer 1 and in the vicinity thereof, both nozzles 31
The abrasive is supplied simultaneously from a and 31b. When the abrasive is supplied from both nozzles 31a and 31b at the same time, the flow rate of the abrasive is set to half of that when the abrasive is supplied from only one of the nozzles.

Similarly, when the number of nozzles is three or more, a combination of one or more nozzles that can supply the polishing agent most efficiently between the silicon wafer 1 and the polishing pad 6 is selected. I do. Further, the flow rate of the abrasive to be supplied from each nozzle is set according to the number of selected nozzles.

Before the actual polishing operation is started, the relationship between the nozzles selected as described above, the flow rate of each nozzle, and the output signal of the angle sensor 43 is set in the polishing agent supply control device 41 in advance. Keep it.

(Example 2) FIG. 3 shows another example of a CMP apparatus according to the present invention.

In this example, as a mechanism for moving the polishing head 7 in a plane parallel to the surface to be polished, instead of the arm 11 and the column 12 in the example shown in FIG.
A portal frame 15 and a linear motion mechanism 17 are used. Other configurations are the same as those in the example shown in FIG.

A linear motion mechanism 17 that runs along the beam 16 is supported on the lower surface of the beam 16 of the portal frame 15. The polishing head 7 is fixed to a shaft of a motor 8, and a housing of the motor 8 is mounted below the above-mentioned linear motion mechanism 17 via an air cylinder 9 and a linear motion guide 10. The linear motion mechanism 17 reciprocates along the beam 16. Along with this, the polishing head 7 moves between one peripheral portion and the other peripheral portion of the silicon wafer 1 in a plane parallel to the surface to be polished and on a turning trajectory passing through the center of the silicon wafer 1. Reciprocate with.

The linear motion mechanism 17 is provided with a position sensor 45 (linear scale) for detecting its position. The abrasive supply control device 41 receives an output signal from the position sensor 45, and according to a preset instruction, according to the position of the linear motion mechanism 17, each of the abrasive supply pumps 33a,
By individually controlling the nozzles 33b, each nozzle 31
a, the supply amount of the polishing agent from 31b is individually controlled.

FIG. 4 shows an example of a method of controlling the supply of the polishing agent from each of the nozzles 31a and 31b according to the position of the polishing head 7 with respect to the silicon wafer 1 in this CMP apparatus.

Also in this example, the supply of the abrasive from each nozzle is controlled in the same manner as in the example shown in FIG. That is, when the polishing head 7 is at the position A or the position C on the silicon wafer 1, the nozzle 31b or 31a located on the rear side in the rotation direction of the turntable 2 with respect to the polishing head 7 is selected. The abrasive is supplied from the nozzle 31b or 31a. When the polishing head 7 is at the position B on the silicon wafer 1, the abrasive is supplied from both nozzles 31a and 31b at the same time. When the abrasive is supplied from both nozzles 31a and 31b at the same time, the flow rate of the abrasive is set to half of that when the abrasive is supplied from only one of the nozzles.

(Example 3) FIG. 5 shows another example of a CMP apparatus according to the present invention. In the figure, 10 is a linear motion guide, 51 is a nozzle for supplying an abrasive, and 61 is a nozzle position control device (control device).

In this example, instead of providing a plurality of nozzles for supplying the polishing agent around the polishing head as in the example shown in FIG. 1, the nozzles can be swiveled along the outer periphery of the polishing head. Make up. Other configurations are the same as those in the example shown in FIG.

A nozzle 51 for supplying an abrasive is arranged adjacent to the outer periphery of the polishing head 7. This nozzle 51
Is supported around the shaft portion of the polishing head 7 via a rotary joint 55, and can be turned by the motor 54 along the outer periphery of the polishing head 7. The motor 54 is supported on the lower surface of the housing of the motor 8 for driving the polishing head. The abrasive is supplied from an abrasive supply pump (not shown) to the nozzle 51 via a tube 52 and a flow path formed in the rotary joint 55.

The nozzle 51 is angled toward the center of the polishing head 7 so that the polishing agent can be efficiently supplied to the polishing head 7.

An angle sensor 43 for detecting the turning angle of the arm 11 is attached near the base of the column 12 that supports and turns the arm 11. The nozzle position control device 61 receives the output signal from the angle sensor 43 and controls the turning position of the nozzle in accordance with the turning angle of the arm 11 according to a preset instruction. Thus, the polishing agent is supplied to the polishing head 7 from an optimal position.

Referring to FIG. 6, in this CMP apparatus,
An example of a method of controlling the turning position of the nozzle 51 according to the relative position of the polishing head 7 with respect to the silicon wafer 1 will be described. The arrows in the figure represent the rotation directions of the turntable 2 (ie, the silicon wafer 1) and the polishing head 7 (ie, the polishing cloth 6).

In FIG. 6, for example, when the polishing head 7 is at each of the positions A, B and C, the turning position of the nozzle 51 around the polishing head 7 is controlled as follows. That is, when the polishing head 7 is located at the position A (one peripheral portion) on the silicon wafer 1 and between the position A and the position B, the turning position of the nozzle 51 is shifted with respect to the polishing head 7 by the turntable 2. Control so that it comes to the rear side in the rotation direction. Similarly, when the polishing head 7 is located at the position C (the other peripheral portion) on the silicon wafer 1 and between the position C and the position B, the turning position of the nozzle 51 is set to the turntable 2 with respect to the polishing head 7. Is controlled to come to the rear side in the direction of rotation of. Further, when the polishing head 7 passes through the position B (center portion) on the silicon wafer 1, the nozzle 51 is swiveled about 180 degrees with respect to the polishing head 7 so that the above condition is maintained.

Before starting the actual polishing operation, the turning position of the nozzle 51 and the angle sensor 43 selected as described above are used.
The relationship with the output signal of the nozzle position control device 61
Set to. (Example 4) FIG. 7 shows another example of the CMP apparatus according to the present invention.

In this example, as a mechanism for moving the polishing head 7 in a plane parallel to the surface to be polished, a gate-shaped frame is used instead of the arm 11 and the column 12 in the example shown in FIG. 15 and a linear motion mechanism 17 are used. Other configurations are the same as those in the example shown in FIG.

A linear motion mechanism 17 running along the beam 16 is supported on the lower surface of the beam 16 of the portal frame 15. The polishing head 7 is fixed to a shaft of a motor 8, and a housing of the motor 8 is mounted below the above-mentioned linear motion mechanism 17 via an air cylinder 9 and a linear motion guide 10. The linear motion mechanism 17 reciprocates along the beam 16. Along with this, the polishing head 7 moves between one peripheral portion and the other peripheral portion of the silicon wafer 1 in a plane parallel to the surface to be polished and on a turning trajectory passing through the center of the silicon wafer 1. Reciprocate with.

The linear motion mechanism 17 is provided with a position sensor 45 (linear scale) for detecting the position. The nozzle position control device 61 receives the output signal from the position sensor 45 and controls the turning position of the nozzle 51 according to the position of the translation mechanism 17 according to a preset instruction.

FIG. 8 shows an example of a method for controlling the turning position of the nozzle 51 in accordance with the relative position of the polishing head 7 with respect to the silicon wafer 1 in this CMP apparatus.

Also in this example, the turning position of the nozzle 51 around the polishing head 7 is controlled in the same manner as in the example shown in FIG. That is, when the polishing head 7 is at the position A (and between the position A and the position B) or the position C (and between the position C and the position B) on the silicon wafer 1,
The turning position of the nozzle 51 is controlled so as to be located rearward with respect to the polishing head 7 in the rotation direction of the turntable 2. When the polishing head 7 passes through the position B on the silicon wafer 1, the nozzle 51 is swiveled about 180 degrees with respect to the polishing head 7 so that the above condition is maintained.

[0051]

According to the planar polishing apparatus of the present invention, in a planar polishing apparatus using a polishing tool having a smaller area than the surface to be polished of the workpiece, the polishing head is mounted on the turntable for holding the workpiece. The abrasive can be supplied to the polishing head from an optimum position according to the relative position. Thus, the supply amount of the abrasive to the surface to be polished is stabilized without being affected by the change in the position of the polishing head with respect to the turntable, so that the processing speed is stabilized. As a result, good planar accuracy can be achieved for the polished surface after polishing.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a planar polishing apparatus according to the present invention.

FIG. 2 is a view showing an example of a method of selecting a nozzle for supplying an abrasive in accordance with a relative position of a polishing head to a surface to be polished in the planar polishing apparatus shown in FIG.

FIG. 3 is a schematic configuration diagram showing another example of the planar polishing apparatus according to the present invention.

FIG. 4 is a view showing an example of a method of selecting a nozzle for supplying an abrasive in accordance with a relative position of a polishing head with respect to a surface to be polished in the planar polishing apparatus shown in FIG.

FIG. 5 is a schematic configuration diagram showing another example of the planar polishing apparatus according to the present invention.

6 is a view showing an example of a method of controlling a turning position of a nozzle for supplying an abrasive in accordance with a relative position of a polishing head with respect to a surface to be polished in the planar polishing apparatus shown in FIG.

FIG. 7 is a schematic configuration diagram showing another example of the planar polishing apparatus according to the present invention.

8 is a diagram showing an example of a method of controlling a turning position of a nozzle for supplying an abrasive in accordance with a relative position of a polishing head with respect to a surface to be polished in the planar polishing apparatus shown in FIG.

FIG. 9 is a schematic configuration diagram showing an example of a conventional planar polishing apparatus.

FIG. 10 is a diagram showing a relationship between a position of a polishing head with respect to a surface to be polished and a position of a nozzle for supplying an abrasive in the planar polishing apparatus shown in FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Silicon wafer (workpiece), 2 ... Turntable, 4 ... Nozzle for supplying abrasives, 5 ... Abrasives, 6 ... Polishing cloth (polishing tool), 7 ..Polishing head, 8 ... motor for driving the polishing head, 9 ... air cylinder, 10 ... linear guide, 11 ... arm (moving mechanism), 12 ... column, 15 ...・ Gate frame, 16 ・ ・ ・ Beam, 17 ・ ・ ・ Linear mechanism (moving mechanism), 31a, 31b ・ ・ ・ Nozzle, 32a, 32b ・ ・ ・ Tube, 33a, 33b ・ ・ ・ Abrasive supply pump, 41: abrasive supply control device (control device), 43: angle sensor, 45: position sensor, 51: nozzle, 52: tube, 54: motor for nozzle rotation, 55 ... rotating joint, 61 ... nozzle position control Device (control device).

Claims (4)

[Claims] 1. A turntable on which a flat work piece is held on an upper surface, and a polishing tool having a smaller area than a surface to be polished of the work piece, which is arranged to face the upper surface of the turntable, is mounted. ,
A polishing head for polishing the surface to be polished by pressing the polishing tool against the surface to be polished while rotating, and a moving mechanism for moving the polishing head in a plane parallel to the surface to be polished; A plurality of nozzles provided near the outer periphery of the polishing head for supplying an abrasive to the surface to be polished from the periphery of the polishing head, and are preset according to the position of the polishing head with respect to the turntable. A control device for individually controlling an amount of the abrasive supplied from each of the nozzles according to an instruction; 2. The control device according to claim 2, wherein the control device selectively supplies the polishing agent from a nozzle located at a rear side in a rotation direction of the turntable with respect to the polishing head among the plurality of nozzles. 2. The apparatus according to claim 1, wherein the amount of the abrasive supplied from each nozzle is controlled according to the number of nozzles for supplying the abrasive. 3. A turntable on which a flat workpiece is held on an upper surface, and a polishing tool having an area smaller than the surface to be polished of the workpiece, which is disposed to face the upper surface of the turntable, is mounted. ,
A polishing head for polishing the surface to be polished by pressing the polishing tool against the surface to be polished while rotating, and a moving mechanism for moving the polishing head in a plane parallel to the surface to be polished; A nozzle that is provided near the outer periphery of the polishing head, moves along the outer periphery of the polishing head, and supplies an abrasive to the surface to be polished from around the polishing head; A control device for controlling the position of the nozzle according to a preset instruction in accordance with the position; 4. The control device according to claim 3, wherein the control device controls the position of the nozzle so that the nozzle is located rearward of the polishing head in a direction of rotation of the turntable. A flat polishing apparatus according to item 1.