JP2002346910A - Polishing method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing device allowing polishing in an optimum state by bringing a working surface of an object to be polished into uniform pressure contact with the surface of a pad and improvement of polishing performance, a polishing rate and productivity. SOLUTION: In this polishing method for polishing an object 3 to be polished supported by a rotating polishing head by bringing the object 3 into pressure contact with the surface of the pad 2 provided on a rotating surface plate and making the surface uniform by bringing a rotating pad conditioner 4 into pressure contact with the surface of the pad 2, polishing of the object 3 to be polished by a polishing head 5 and conditioning of the surface of the pad 2 by the pad conditioner 4 are coaxially performed. Since polishing can be performed by making the angle of the polishing head 5 to the surface of the pad 2 same as that of the pad conditioner 4 to the surface of the pad 2, the working surface of the object 3 to be polished is in uniform pressure contact with the surface of the pad 2. The angle is normally set to a right angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method and apparatus for polishing a thin plate-like object to be polished, and more particularly to a chemical mechanical polishing (CMP) method and apparatus for a semiconductor wafer, a glass plate for an LCD, and the like. Things.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional apparatus for polishing a workpiece such as a semiconductor wafer. In FIG. 1, a pad 2 is fixed on a surface plate 1 having a rotating mechanism by a double-sided tape or the like. Above the platen 1, a polishing head 5 for holding a thin plate-like workpiece 3 such as a wafer is provided. The rotating shaft 5a of the polishing head 5 is connected to a rotating / elevating mechanism 6 such as a cylinder. The polishing head 5 is provided with a suction film 10 as a suction holding and buffer material on a surface holding the work 3. In addition, a retainer ring 7 is provided on the outer peripheral portion of the polishing head 5 so that the workpiece 3 does not protrude from the polishing head 5.

In order to make the surface of the pad 2 roughened by polishing uniform, a pad conditioner 4 connected to a rotating / elevating mechanism 9 is provided at a position different from the polishing head 5. At the same time as the polishing of the object 3 or at the time of non-polishing, the pad conditioner 4 is pressed onto the pad 2 in the same manner as the polishing head 5, and the pad conditioning is performed while rotating. In FIG. 5, reference numeral 8 denotes an abrasive supply hose, and reference numeral 18 denotes a slurry abrasive.
Reference symbol A indicates the rotation direction of the platen 1, and reference symbol B indicates the rotation direction of the polishing head 5.

[0004]

In the above-mentioned conventional polishing apparatus, the polishing head 5 and the pad conditioner 4 are arranged independently of each other. However,
In this polishing apparatus, the angle between the axis of the polishing head 5 and the pad surface (square angle) and the angle between the axis of the pad conditioner 4 and the pad surface (square angle) due to mechanical accuracy errors and assembly accuracy errors. A slight error is likely to occur during the period.

That is, as shown in the schematic diagram of FIG. 6, when the angle between the surface of the pad 2 and the axis of the polishing head 5 is θ1, and the angle between the surface of the pad 2 and the axis of the pad conditioner 4 is θ2. , The angles θ1 and θ2 do not become equal (θ1 ≠ θ2). The squareness error (the difference between the angles θ1 and θ2) is generally about 1/2000 in the circumferential direction of the surface of the pad 2.

In the state shown in FIG. 6, when the polishing head 5 is brought into contact with the pad 2 during polishing and pressurized, due to the squareness error, the processed surface of the workpiece 3 does not conform to the surface of the pad 2. Pressurized uniformly. When polishing is performed in this state, a difference occurs in the pressure applied to the object 3 to be polished, and the polishing amount increases in a portion that is strongly pressed, and decreases in a portion that is weakly pressed. As a result, the polishing performance (in-plane uniformity, flatness) of the work 3 is deteriorated.

In the state shown in FIG. 6, if the polishing is performed by rotating the polishing head 5 and the pad conditioner 4 at a high speed, a high-precision polishing performance cannot be obtained. Therefore, the polishing must be performed at a low speed. Disappears. For this reason, the polishing time becomes longer, the productivity becomes worse, and the polishing performance is poor, so that it is necessary to frequently carry out the polishing condition determination and the replacement of the consumables, and the man-hours, setup time, cost are increased, and the yield is poor. There was a problem.

The present invention has been made in view of the above-mentioned problems of the prior art, and enables an object to be polished to be uniformly pressed against a pad surface and processed in an optimum state, thereby improving polishing performance, polishing rate and productivity. It is an object of the present invention to provide a polishing method and apparatus capable of performing polishing.

[0009]

In order to achieve the above object, a polishing method according to the present invention is directed to a polishing method in which an object to be polished supported by a rotating polishing head is pressed against a surface of a pad provided on a rotating surface plate. In addition, in a polishing method in which a rotating pad conditioner is pressed against a pad surface to make the surface uniform, an angle of the polishing head with respect to the pad surface is set to be equal to an angle of the pad conditioner with respect to the pad surface. And The angle is usually
Set at right angles.

According to this polishing method, the entire processing surface of the object to be polished is uniformly pressed against the pad surface, so that the polishing performance such as in-plane uniformity and flatness of the object to be polished after polishing is improved. Further, since the wafer can be polished under the high-speed rotation condition, the polishing rate is improved, and the yield is improved, so that the productivity can be improved.

The polishing apparatus according to the present invention is characterized in that an object to be polished supported by a rotating polishing head is brought into pressure contact with a surface of a pad provided on a rotating surface plate for polishing, and a rotating pad conditioner is polished. In the polishing apparatus, the surface is polished by pressing with a polishing head, and the conditioning of the pad surface by the pad conditioner is performed coaxially. Here, "performing coaxially" means that the axis of the rotation axis of the polishing head and the axis of the rotation axis of the pad conditioner are the same. Since the polishing and the conditioning are performed coaxially, the polishing can be performed with the angle of the polishing head to the pad surface being the same as the angle of the pad conditioner to the pad surface. The angle is usually set to a right angle.

Further, the polishing apparatus according to the present invention is characterized in that an object to be polished supported by a rotating polishing head is brought into pressure contact with a surface of a pad provided on a rotating surface plate to polish the object, and a rotating pad conditioner is polished. In a polishing apparatus that makes the surface uniform by pressing against, the polishing head and the pad conditioner are supported by an angle adjustment mechanism capable of adjusting the angle with respect to the pad surface, and the angle is measured by an angle measuring device. By operating the angle adjusting mechanism based on the measured value, the angle of the polishing head with respect to the pad surface is set to be the same as the angle of the pad conditioner with respect to the pad surface. In the present invention,
The rotation of the polishing head and the pad conditioner may be performed coaxially as described above, or may be performed on another axis (the axis position of the rotation axis of the polishing head and the axis position of the rotation axis of the pad conditioner are different). You can also.

In the polishing apparatus according to the present invention, the polishing head and the pad conditioner are rotated on separate axes as described above. That is, the rotation / elevation mechanism of the polishing head and the rotation / elevation mechanism of the pad conditioner are supported by separate angle adjustment mechanisms via a rotatable arm, and the angle measuring device is connected to the rotation axis of the polishing head and the pad. The angle of the polishing head with respect to the pad surface and the angle of the pad conditioner with respect to the pad surface are separately provided on the rotation axis of the conditioner and brought into contact with the pad surface while rotating these angle measuring devices about the rotation axis. The arm is rotated by an angle adjusting mechanism based on the measured value, and the two angles are set to be the same.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3,
5 and 6 are denoted by the same reference numerals.

Embodiment 1 FIG. 1 is a plan view showing the overall configuration of a polishing system provided with a polishing apparatus of the present invention, and FIG. 2 is a vertical sectional side view of the polishing apparatus of FIG. The polishing system includes a polishing unit 11 (a polishing apparatus of the present invention) in which a polishing head 5 for polishing a workpiece 3 and a pad conditioner 4 for conditioning a pad 2 are provided coaxially.
1, a slurry supply unit 12 for supplying a slurry used at the time of polishing, a cleaning unit 13 for cleaning and drying an object to be polished such as a polished wafer, and the cleaning unit 1
3 includes a chemical supply unit 14 that supplies a cleaning chemical (for example, a mixed aqueous solution of HF and NH ₃ ) used in 3, and a transport unit 16. This transport unit 16
After the object 3 in the cassette 15 is conveyed to the polishing unit 11 and then to the cleaning unit 13, the object 3 to be subjected to a predetermined process is collected in the cassette 15.

As shown in FIG. 2, the polishing unit 11 comprises:
The polishing apparatus includes a polishing head 5 arranged on the surface plate 1 and a pad conditioner 4 provided on an outer peripheral portion of the polishing head 5. The polishing head 5 and the pad conditioner 4 have the same reference axis. That is, the rotation axis 5a of the polishing head 5 and the rotation axis 4a of the pad conditioner 4 are coaxially provided, and therefore, the angle (θ1 in FIG. 6) of the polishing head 5 with respect to the pad 2 is always set to the pad condition. 6 with respect to the pad 2 (θ in FIG. 6)
It is kept equal to 2).

The rotating shafts 4a and 5a are connected to a rotating / elevating mechanism 6 supported by an angle adjusting mechanism 19, and their rotation speeds are independently variable. The pad conditioner 4 attached to the rotating shaft 4a is a cylindrical body whose lower part is entirely open, is fitted on the outer periphery of the polishing head 5 and the retainer ring 7, and is relatively to the polishing head 5. It is rotatable. The angle adjustment mechanism 19 serves to finely adjust the angle of the reference axis with respect to the surface of the pad 2, and moves the rotation / elevation mechanism 6 in the radial direction of the surface of the pad 2 to uniformly cover the entire surface of the pad 2 with the pad conditioner 4. And performs the role of pad conditioning. Preferably, the angles (θ1, θ2) are right angles, whereby the polishing performance can be particularly enhanced.

Further, the pad 2 is fixed on a surface plate 1 having a rotating mechanism (not shown) with a double-sided tape or the like. On the surface of the surface plate 1, the polishing head 5 for holding the workpiece 3 is provided. is set up. The polishing head 5 is provided with a suction holding material and a suction film 10 as a buffer material on a surface for holding the workpiece 3. Also, the retainer ring 7 is used to prevent the workpiece 3 from jumping out of the polishing head 5.
Is provided.

Next, the operation of the polishing apparatus will be described. During polishing, the platen 1 is rotated in the direction of arrow A and the polishing head 5 is rotated in the direction of arrow B while the slurry 18 in the form of slurry is supplied onto the pad 2 by the slurry supply hose 8. Rotating / elevating mechanism 6 while rotating polishing head 5
To be polished, and brought into contact with the pad 2 under pressure.
Polish. At this time, the polishing head 5 has a rotating / elevating mechanism 6.
Power is further transmitted through the rotating shaft 5a, and the polishing head 5
The object to be polished 3 is polished by the difference between the rotation speed of the platen 1 and the rotation speed of the platen 1.

On the other hand, the pad conditioner 4 rotates and
Power is transmitted from the lifting mechanism 6 via the rotating shaft 4 a, and the pad 2 is conditioned by contact with the pad 2. This conditioning can be performed in parallel with the polishing step or can be performed during non-polishing. In any case, since polishing and conditioning can be performed coaxially and the same, high-precision polishing performance can be obtained.

Second Embodiment FIG. 3 shows a polishing apparatus according to a second embodiment of the present invention. Pad 2 on platen 1 having a rotating mechanism (not shown)
Is fixed with double-sided tape, etc.
A polishing head 5 for holding the workpiece 3 is provided.
The rotating shaft 5a of the polishing head 5 is connected to a rotating / elevating mechanism 6 such as a cylinder and a motor.

The polishing head 5 is provided with a suction film 10 on a surface for holding the object 3 to be polished. Polishing head 5
Is provided with a retainer ring 7 so that the object 3 does not protrude from the polishing head 5. In order to make the surface of the pad 2 roughened by polishing uniform, a pad conditioner 4 connected to a rotating / elevating mechanism 9 is provided at a position different from the polishing head 5. At the same time as polishing of the workpiece 3 or at the time of non-polishing, the pad conditioner 4
Is pressed onto the pad 2 in the same manner as the polishing head 5, and the pad 2 is conditioned while being rotated.

In this polishing apparatus, the polishing head 5 is supported by an angle adjusting mechanism 21. That is, the rotating / elevating mechanism 6 of the polishing head 5 is attached to the angle adjusting mechanism 21 via the arm 20, and the arm 22 is attached to the rotating shaft 5a.
A contact member (angle measuring device) 23 for contacting the pad 2 via the. The contact member 23 is used to measure the angle of the polishing head 5 with respect to the pad 2 by rotating the polishing member 5 integrally with the polishing head 5 before starting the polishing process and measuring the shape and dimensions of the pad 2 in the radial direction. is there. The arm 20 is rotated up and down by the angle adjusting mechanism 21 based on the angle measurement value, and the rotating / elevating mechanism 6, the rotating shaft 6a attached to the mechanism and the polishing head 5 are indicated by dashed lines. As shown, the pad 2 of the polishing head 5
Fine-tune the angle to. This angle is preferably a right angle, so that the polishing performance can be particularly enhanced.

The pad conditioner 4 is held by the angle adjusting mechanism 26. That is, the rotating / elevating mechanism 9 of the pad conditioner 4 is attached to the angle adjusting mechanism 26 via the arm 25. A contact member (angle measuring device) for the rotating shaft 4a with the pad 2 via the arm 27
28 are provided. The contact member 28 is used to measure the angle of the pad conditioner 4 with respect to the pad 2 by measuring the shape and size of the pad 2 in the deformation direction by rotating together with the polishing head 5 before starting the polishing process. It is. Then, based on the angle measurement value, the arm 25 is rotated up and down by the angle adjustment mechanism 26, and the rotation / elevation mechanism 9, the rotation shaft 4a and the pad conditioner 4 attached to the mechanism 25 are indicated by a dashed line. As shown, the angle of the pad conditioner 4 with respect to the pad 2 is finely adjusted. This angle is preferably a right angle, so that the polishing performance can be particularly enhanced.

Before polishing by the polishing apparatus, the contact members 23 and 28 and the angle adjusting mechanisms 21 and
6 makes the angle of the polishing head 5 with respect to the pad 2 equal to the angle of the pad conditioner 4 with respect to the pad 2 (generally a right angle). After the angle adjustment, since the contact members 23 and 28 are unnecessary, the rotating shafts 4a and
Remove from 6a. As described above, by making the angles of the polishing head 5 and the pad conditioner 4 with respect to the pad 2 equal, a squareness error is eliminated, and the processed surface of the workpiece 3 is uniformly pressed. Performance (in-plane uniformity, flatness) is improved.

Experimental Example Pad conditioning and wafer polishing were performed under the conditions shown in Table 1 below using the polishing apparatus of Embodiment 2 (FIG. 3). For comparison, the wafer was polished under the same conditions using a conventional polishing apparatus as shown in FIG. 49 points on the wafer surface were measured, and the in-plane uniformity was calculated by the following equation. The more uniform the polishing, the lower this in-plane uniformity value. In-plane uniformity = ｛(MAX point−MIN point) / (MAX point +
(MIN point)｝ × 100 (%)

[0027]

[Table 1]

FIG. 4 shows the results. The solid line is the experimental result according to the present embodiment, and the broken line is the experimental result using the conventional polishing apparatus. It is apparent that the polishing apparatus of the present invention has improved in-plane uniformity, which is one of the polishing characteristics, as compared with the conventional apparatus. In the high-speed rotation area (high polishing head rotation speed), the in-plane uniformity has been dramatically improved.
It can be seen that the high-speed rotation condition of the polishing apparatus of the present invention has better in-plane uniformity and the wafer can be polished under the high-speed rotation condition than the low-speed rotation condition of the conventional apparatus.

[0029]

As described above in detail, the polishing method and apparatus of the present invention are configured such that the angle of the pad conditioner with respect to the pad is equal to the angle of the polishing head with respect to the pad. Therefore, when the object to be polished is pressed against the pad surface, the entire processing surface of the object to be polished is uniformly pressed, so that the polishing performance such as in-plane uniformity and flatness of the object to be polished is improved. . Further, since the wafer can be polished under the high-speed rotation condition, the polishing rate is improved, and the yield is improved, so that the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing an overall configuration of a polishing system provided with a polishing apparatus according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional side view of the polishing apparatus of FIG.

FIG. 3 is a vertical sectional side view of a polishing apparatus according to Embodiment 2 of the present invention.

FIG. 4 is a graph showing a comparison between a result of a polishing experiment performed by the polishing apparatus of the second embodiment and a result of a polishing experiment performed by a conventional polishing apparatus.

FIG. 5 is a vertical sectional side view of a conventional polishing apparatus.

FIG. 6 is a schematic diagram showing a squareness error between a polishing head and a pad conditioner in a conventional polishing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Surface plate, 2 ... Pad, 3 ... Workpiece, 4 ... Pad conditioner, 4a ... Rotary shaft, 5 ... Polishing head, 5a ... Rotary shaft, 6 ... Rotating / elevating mechanism, 7 ... Retainer ring, 8 ...
Abrasive supply hose, 9: rotating / elevating mechanism, 10: adsorption film, 11: polishing unit, 12: slurry supply unit, 13: cleaning unit, 14: chemical liquid supply unit,
15: cassette, 16: transport unit, 18: abrasive,
19: Angle adjusting mechanism 20, 25: Arm, 21, 26 ...
Angle adjustment mechanism.

Claims (4)

[Claims] An object to be polished, which is supported by a rotating polishing head, is pressed against a surface of a pad provided on a rotating surface plate for polishing, and a rotating pad conditioner is pressed against the surface of the pad to make the surface uniform. A polishing method, wherein an angle of a polishing head with respect to a pad surface is set to be the same as an angle of a pad conditioner with respect to a pad surface. 2. An object to be polished supported by a rotating polishing head is polished by being pressed against a surface of a pad provided on a rotating surface plate, and a rotating pad conditioner is pressed against the surface of the pad to make the surface uniform. A polishing apparatus, wherein polishing of an object to be polished by a polishing head and conditioning of a pad surface by a pad conditioner are performed coaxially. 3. An object to be polished supported by a rotating polishing head is polished by being pressed against a surface of a pad provided on a rotating platen, and a rotating pad conditioner is pressed against the surface of the pad to make the surface uniform. In the polishing apparatus, the polishing head and the pad conditioner are supported by an angle adjusting mechanism capable of adjusting the angle with respect to the pad surface, and the angle is measured by an angle measuring instrument, and the angle is adjusted based on the measured value. A polishing apparatus, wherein an angle of a polishing head with respect to a pad surface is set to be equal to an angle of a pad conditioner with respect to a pad surface by operating a mechanism. 4. A polishing head rotating / elevating mechanism and a pad conditioner rotating / elevating mechanism are supported by separate angle adjusting mechanisms via a rotatable arm, and the angle measuring device is rotated by the polishing head. Shaft and the rotation axis of the pad conditioner are separately provided, and by contacting the angle measuring device with the pad surface while rotating the angle measurement device with the rotation axis, the angle of the polishing head with respect to the pad surface and the angle of the pad conditioner with respect to the pad surface are reduced. The arm is rotated by an angle adjusting mechanism based on the measured value, and the angle
The polishing apparatus according to claim 3, wherein the three angles are set to be the same.