JP2002246342A - Polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably supply slurry onto the surface to be polished of a wafer 10, and to uniformly polish the surface of the wafer, in a polishing device for polishing the wafer 10. SOLUTION: An ultrasonic vibrator 9 is brought into contact with the liquid surface of the slurry 8 for applying ultrasonic vibration, so that rubbish 12 of a polishing pad 2, that is generated by the setting of the polishing pad 2 and is contained in the slurry 8, cannot be blocked, and chips 12 are disconnected from the hole 11 for transport for discharging to the outside of the polishing pad 2, thus stabilizing the supply of slurry.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for polishing and flattening irregularities in an insulating film, a wiring film and a semiconductor film formed on one main surface of a semiconductor wafer.

[0002]

2. Description of the Related Art In recent years, with the integration of semiconductor integrated circuits, insulating layers and wiring layers have been repeatedly laminated on a surface of a semiconductor wafer (hereinafter simply referred to as a wafer). However, every time these insulating layers and wiring layers are laminated, irregularities are generated on the surface, and there is a problem that the irregularities cannot be completely covered by the depth of focus of the exposure apparatus. As a method for solving this problem, flattening by a chemical mechanical polishing method has been generally used.

FIG. 4 is a view showing an example of a conventional polishing apparatus, and FIG. 5 is an enlarged view of a part of the polishing table shown in FIG. Conventionally, this type of polishing apparatus includes, for example, a polishing table 1 on which a polishing pad 2 is attached, as shown in FIG.
A wafer carrier 3 for holding the wafer and pressing the wafer 10 against the polishing pad 2, a nozzle 5 for dropping slurry onto the polishing pad 2, and a disk 7 Is provided on the surface of the polishing pad 2 to sharpen the polishing pad 2.

In order to polish a wafer 10 with this polishing apparatus, a slurry 8 is dropped from a nozzle 5 onto a polishing pad 2 while rotating a polishing table 1, and a load is applied to a wafer carrier 3 holding the wafer 10. The surface of the wafer 10 is polished. At this time, it is one of the important factors to stabilize the polishing rate of the wafer 10 and uniformly polish the wafer surface. .

Further, dressing of the polishing pad 2 by the disk 7 of the pad conditioner 6 has been performed before or during polishing of the wafer 10. For this dressing, the pad conditioner 6 was swung in the radial direction of the polishing table 1 to sharpen the entire surface of the polishing pad 2.

On the other hand, there is almost no gap between the holding ring 4 of the wafer carrier 3 and the polishing pad 2, and the slurry entering the wafer is limited. Therefore, a large number of transport holes 11 are formed on the surface of the polishing pad 2 so that the slurry 8 is efficiently supplied into the wafer. The hole 11 has a function of transporting the slurry 8 and stably supplies the slurry 8 within the wafer surface.

[0007]

However, the chips 12 of the polishing pad 2 which are shaved off by the disk 7 are not shown in FIG.
As shown in (1), there is a problem that the supply of the slurry 8 into the surface of the wafer 10 held by the wafer carrier 3 is reduced due to the clogging of the hole into the hole 11 for transportation and the polishing of the wafer 10 becomes unstable. Had occurred.

[0008] In addition, there has been a quality problem that debris from the polishing pad made of foamed polyurethane resin adheres to the wafer surface and contaminates the flattened wafer surface. Further, when sharpening the polishing pad, there is a problem that chips of the polishing pad adhere between diamond abrasive grains embedded in the disk, resulting in poor sharpness.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a polishing apparatus capable of uniformly supplying a slurry to a surface to be polished of a wafer and uniformly polishing the wafer surface.

[0010]

SUMMARY OF THE INVENTION The features of the present invention include a wafer carrier that holds and rotates a semiconductor wafer, a polishing pad that contacts the surface of the semiconductor wafer and polishes the semiconductor wafer, and a polishing pad that attaches and rotates the polishing pad. A polishing table having a polishing table, a disk conditioner having a disk which oscillates in the radial direction of the polishing table to sharpen the polishing pad, a nozzle for dropping slurry onto the polishing pad, and a polishing table. An ultrasonic vibrator, which is in contact with the surface of the slurry dropped on the pad and liquid leveled on the polishing pad, moves in the surface of the polishing pad.

Preferably, the ultrasonic transducer is supported by the rotating wafer carrier. And
Specifically, it is preferable that a plurality of the ultrasonic transducers are evenly arranged outside a retaining ring for preventing the semiconductor wafer from jumping out of the wafer carrier. If necessary, a stainless steel plate attached to the vibration surface of the ultrasonic transducer is provided.

On the other hand, it is desirable that the ultrasonic vibrator is also arranged around the pad conditioner. Preferably, another ultrasonic vibrator is mounted on the disk mounting surface of the pad conditioner.

[0013]

Next, the present invention will be described with reference to the drawings.

FIGS. 1A and 1B are views showing a polishing apparatus according to an embodiment of the present invention and a view in which a part of a polishing table is cut away and enlarged. This polishing device,
As shown in FIG. 1A, there is provided an ultrasonic vibrator 9 which comes into contact with the liquid level of a slurry 8 entering the wafer surface around the wafer carrier 3 and moves with the rotation of the wafer carrier 3. . That is, a plurality of ultrasonic transducers 9 are arranged uniformly outside the holding ring 4 of the wafer carrier 3.

Other polishing tables 1, a pad conditioner 6 having a disk 7 having a number of cutting edges of diamond abrasive grains, a nozzle 5, a wafer carrier 3, and a polishing pad 2 are the same as those of the above-mentioned conventional example. is there.

The ultrasonic vibrator 9 is a steel plate 14 attached to the vibration transmitting surface of the ultrasonic vibrator 9 instead of directly contacting the liquid surface of the slurry 8. The steel plate 14 is desirably hardly rusted, for example, stainless steel. The thickness of the stainless steel is, for example, about ｍｍ of the wavelength when the frequency is 300 KHz, that is, about 3 mm. Then, a casing for wrapping each ultrasonic transducer 9
It is desirable to mount a plurality of wafers around the wafer carrier 3 via the support member 13 at equal intervals.

Next, the operation of removing dust from the polishing pad 2 will be described. First, the debris 12 generated by being dressed by the pad conditioner 6 is supplied in a state of being contained in a slurry 8 which is dropped and is liquid-filled on the polishing pad 2. Then, as shown in FIG. 1 (b), the rotation of the polishing table 1 causes
And the hole 11 is closed. However, the vibration of the ultrasonic vibrator 9 near the wafer carrier 3 causes the debris 12 to rise up from the hole 11, and has a function of rotating the polishing table 1 and a function of pushing out the slurry 8 by the rotation of the wafer carrier 3. Accordingly, the waste 12 is discharged out of the wafer carrier 3.

As described above, the dust 12 remaining in the hole 11 of the polishing pad 2 is discharged from the hole 11 by the ultrasonic vibration energy and the rotation of the wafer carrier 3, and the dust in the hole 11 around the wafer carrier 3 is formed. 12 is eliminated,
Stable supply of the slurry 8 becomes possible. As a result, a reduction in the wafer polishing rate is eliminated, and the uniformity of polishing within the wafer surface is obtained.

FIG. 2 is a partial cutaway view of a pad conditioner showing a modification of the polishing apparatus of FIG. In this polishing apparatus, as shown in FIG. 3, a plurality of ultrasonic vibrators 9 are arranged around a pad conditioner 6, and dust 12 generated at the time of dressing by a disk 7 is discharged from a hole 11 for transportation. ing.

The ultrasonic vibrator 9 is attached to the holding member 13a derived from the flange of the pad conditioner 6, as in the above-described embodiment.
The surroundings are wrapped in a case to prevent contamination. Further, a steel plate 14a made of stainless steel is attached to a portion that comes into contact with the slurry 8 so as not to rust.

The pad conditioner 6 swings in the direction indicated by the arrow, and dresses the entire surface of the polishing pad 2 on the polishing table rotating in the direction indicated by the arrow. At this time, the debris 12 discharged from the pad conditioner 6 is discharged out of the polishing table 1 as the polishing table 1 rotates. As described above, if the pad conditioner 6 is provided with the ultrasonic vibrator 9 in addition to the ultrasonic vibrator attached to the wafer carrier 3 in the above-described embodiment, the effect of removing the dust 12 from the polishing pad 2 is great. Become.

FIG. 3 is a diagram showing a modification of the pad conditioner of FIG. As shown in FIG. 4, the pad conditioner 6 in this polishing apparatus is mounted such that a plurality of ultrasonic transducers 9a are embedded in a mounting surface of the pad conditioner 6 to the disk 7. Further, it is desirable that the ultrasonic transducers 9a are arranged at the same pitch as the pitch of the transport holes 11 of the polishing pad 2 in the radial direction of the polishing table 1.

When ultrasonic vibration is applied to the disk 7 as described above, the chips of the polishing pad 2 shaved with diamond abrasive grains are not clogged between the diamond abrasive grains, and are formed in the transport holes 11 as chips 12. When the pad conditioner 6 is moved, the ultrasonic transducer 9 moves the hole 1 into the hole 1.
The waste 12 is discharged from 1.

[0024]

As described above, according to the present invention, an ultrasonic wave is applied to the surface of the slurry so that chips generated from the polishing pad and contained in the slurry do not block the holes for transportation. By contacting the vibrator and applying ultrasonic vibration, chips can be detached from the transport hole and discharged out of the polishing pad,
There is an effect that the supply of the slurry is stabilized and the quality of polishing the wafer is improved.

By applying ultrasonic vibration to the disk, the sharpness can be maintained for a long time without clogging between the blade portions of the disk.

[Brief description of the drawings]

FIG. 1 is a diagram showing a polishing apparatus according to an embodiment of the present invention, and is a diagram showing a part of a polishing table in a partially cut away view.

FIG. 2 is a partial cutaway view of a pad conditioner showing a modification of the polishing apparatus of FIG.

FIG. 3 is a diagram showing a modified example of the pad conditioner of FIG. 2;

FIG. 4 is a diagram showing an example of a conventional polishing apparatus.

FIG. 5 is an enlarged view of a part of the polishing table of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polishing table 2 Polishing pad 3 Wafer carrier 4 Retaining ring 5 Nozzle 6 Pad conditioner 7 Disk 8 Slurry 9, 9a Ultrasonic transducer 10 Wafer 11 Hole 12 Debris 13, 13a Holding member

Claims (6)

[Claims] 1. A wafer carrier for holding and rotating a semiconductor wafer, a polishing pad for contacting the surface of the semiconductor wafer and polishing the semiconductor wafer, a polishing table for attaching and rotating the polishing pad, and the polishing table. A pad conditioner comprising a disk which oscillates in the radial direction of the table to sharpen the polishing pad; a nozzle for dropping slurry on the polishing pad; An ultrasonic vibrator that contacts the liquid surface of the slurry and moves within the polishing pad surface. 2. The polishing apparatus according to claim 1, wherein the ultrasonic vibrator is supported by the rotating wafer carrier. 3. The polishing apparatus according to claim 2, wherein a plurality of said ultrasonic vibrators are arranged evenly outside a holding ring for preventing the semiconductor wafer from jumping out of said wafer carrier. . 4. The polishing apparatus according to claim 1, further comprising a stainless steel plate adhered to a vibrating surface of said ultrasonic vibrator. 5. The polishing apparatus according to claim 1, wherein a plurality of said ultrasonic transducers are arranged around said pad conditioner. 6. The polishing apparatus according to claim 5, wherein another ultrasonic vibrator is mounted on a disk mounting surface of said pad conditioner.