GB2358153A

GB2358153A - Slurry feed device

Info

Publication number: GB2358153A
Application number: GB0028486A
Authority: GB
Inventors: Uto Mitsuyoshi
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 1999-11-25
Filing date: 2000-11-22
Publication date: 2001-07-18
Also published as: KR20010051860A; GB0028486D0; KR100385333B1; JP2001150346A

Abstract

A slurry circulation line 2 is connected to an inlet and an outlet of a slurry feed unit 1. Slurry inside the slurry circulation line 2 is subjected to ultrasonic waves generated by an ultrasonic wave oscillator 3 to thereby break up large aggregated particles. Piping 10 connects the slurry circulation line 2 to a point of use 5 (e.g. a chemical-mechanical polishing device). Two pumps 6 and 7 respectively circulate slurry around the circulation line 2 and conduct slurry from the circulation line 2 to the point of use 5 via the piping 10. The piping 10 is connected to the slurry circulation line 2 downstream from the ultrasonic wave oscillator 3. A filter 4 and a valve 7 may be provided in the piping 10. The slurry may contain silica.

Description

2358153 SLURRY FEED DEVICE

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to a slurry feed device for supplying slurry used for polishing, for example, semiconductor substrates to a chemical mechanical polishing (hereinbelow abbreviated as "CMP") device, and particularly to a slurry feed device that prevents aggregation of slurry particles contained in the slurry, thereby suppressing the occurrence of polishing flaws. 2. Description of the Related Art

Slurry feed devices that supply slurry to equipment such as CMP devices used in polishing semiconductor substrates are known in the pr ior art. Fig. 1 is a schematic diagram showing a slurry feed device of the prior art that is adapted for a CMP device. In a priorart slurry feed device, slurry circulation line 101 for circulating slurry is connected to the inlet and outlet of slurry feed unit 100 for supplying slurry. This slurry circulation line 101 is provided with first pump 104 for moving the slurry inside circulation line 101.

Piping 110 connects circulation line 101 and CMP device 103, and this piping 110 is provided with filter 102 for filtering aggregated particles in the slurry. Piping 110 is also provided with second pump 106 for conducting slurry from slurry circulation line 101. Valve 105 is provided between filter 102 and second pump 106 for both, regulating the amount of slurry that is supplied to CMP device 103 and controlling the supply and shut-off of slurry.

Slurry that is prepared at slurry feed unit 100 is pumped and circulated through slurry circulation line 101. by first pump 104 to prevent sedimentation of the slurry.

The slurry inside this circulation line 101 is drawn in by pump 106 and, after undergoing filtration by filter 102 provided in piping 110, is supplied to CMP device 103.

In the ultrasonic wave abrasive grain polisher that is described in Japanese Patent Laid-open No. 156045/95, an ultrasonic wave vibrator is arranged at the base of an. ultrasonic transmission tank that is filled with an ultrasonic transmission fluid. A polishing tank filled with polishing fluid is immersed in the ultrasonic wave transmission fluid in this ultrasonic wave transmission tank. The material to be polished is then placed in the polishing tank, and the ultrasonic waves generated by the ultraso nic wave vibrator are conveyed to the polishing fluid by way of the ultrasonic wave transmission fluid, thereby both preventing sedimentation of the polishing particles contained in the polishing fluid and polishing the material to be polished.

-2 In a case in which slurry is not used in CMP device 103 in the abovedescribed slurry feed device shown in Fig. 1, however, valve 105 is closed and slurry is continuously circulated in slurry circulation line 101. 5 As a consequence, minute silica aggregated particles (slurry particles) contained in the slurry combine with each other to form three- dimensional network structures having weak cohesive strength, the aggregated minute silica particles thus forming larger silica aggregated particles. These large silica aggregated particles not only cause clogging of filter 102 and reduce the life of filter 102, but also cause microscratches on the wafer surface in CMP device 103.

AS in the above-described prior art, moreover, the ultrasonic wave abrasive grain polisher described in Japanese Patent Laid- open No. 156045/95 has the problem that, despite the use of ultrasonic waves both to prevent the sedimentation of slurry particles and to polish the material that is to undergo polishing, the aggregation of polishing particles cannot be prevented.

1 3 SUMMARY OF THE INVENTION

The slurry f eed device according to the present invention comprises: a slurry feed unit for supplying slurry; a slurry circulation line that is connected to the inlet and outlet of the slurry feed unit for circulating the slurry; a first pump for moving the slurry inside the slurry circulation line; an ultrasonic wave oscillator for irradiating ultrasonic waves to slurry inside the slurry circulation line; piping for connecting the slurry circulation line and the point of use of the slurry; and a second pump for conducting the slurry from the slurry circulation line by way of the piping.

In the present invention, sedimentation of the slurry is prevented because the slurry is circulated in the slurry circulation line by the first pump, but slurry particles contained in the slurry tend to aggregate to form larger particles. In this invention, however, ultrasonic waves are irradiated from an ultrasonic wave oscillator onto the slurry in the slurry circulation line. Cohesion of the aggregated slurry particles is thus disrupted and the slurry returns to a state of minute slurry particles. The slurry particles are therefore prevented from forming large aggregated particles.

Accordingly, slurry containing only minute particles can be reliably supplied to the point of use of the slurry A when the slurry is conducted from the slurry circulation line by the second pump. The occurrence of microscratches can thus be suppressed at the point of use of the slurry, such as in a CMP device.

A filter for filtering the slurry is preferably provided in the piping. The provision of a filter enables elimination of extraneous matter contained in the slurry, thereby enabling supply of clean slurry to the point of use of the slurry. In this case, clogging of the filter can be prevented and the life of the filter can be extended because the slurry -in the present invention does not contain large aggregated particles.

In the present invention, the piping is preferably connected to the slurry circulation line downstream in the direction of f low of the slurry from the point of connection of the ultrasonic wave oscillator. in this way, slurry in which cohesion of particles has just been disrupted by ultrasonic waves, that is not aggregated, and that contains only minute particles can be supplied to the point of use of the slurry.

Finally, the point of use of the slurry may be, for example, a chemical mechanical polishing device, and the slurry may contain, for example, silica particles. The above and other objects. features, and advantages of the present invention will become apparent from the following description based on the accompanying drawing which illustrate examples of preferred embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram showing a slurry feed device of the prior art that is adapted f or a CMP device

Fig. 2 is a schematic diagram showing a system ii.-i which a slurry f eed device according to an embodiment oJ the present invention has been adapted for a CMP device DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the accompanying drawing-, detail5 of the slurry feed device according to an embodiment of the present invention are next provided. Fig. 2 is a schematic diagram showing a system in which a slurry fed device according to an embodiment of the present invention has been adapted for a CMP device.

In this embodiment, slurry circulation line 2 for circulating slurry is connected to an inlet and outlet f slurry feed unit 1, which prepares and supplies a slurr(. First pump 6 is provided in slurry circulation line 2, and this first pump 6 causes slurry to circulate in circulation line 2. Ultrasonic wave oscillator 3 for irradiating ultrasonic waves to the slurry is then connected to slurry circulation line 2.

Slurry circulation line 2 is connected to CMP 6 device 5, which is the point of use of the slurry, by means of piping 10. This piping 10 is connected to slurry circulation line 2 downstream in the direction of flow of the slurry from the point of connection of 5 ultrasonic wave oscillator 3.

Piping 10 is further provided with filter 4 for filtering out aggregated particles of the slurry. Piping 10 is also provided with second pump 8 which draws slurry from slurry circulation line 2 and supplies CMP device 5.

Valve 7 is provided between f ilter 4 and second pump 8 for both regulating the amount of slurry that is supplied to CMP device 5 and supplying or halting the supply of slurry to CMP device 5.

In the slurry feed device of this embodiment constructed as described in the foregoing explanation, slurry that has been prepared by slurry feed unit 1 Is supplied to slurry circulation line 2, and the slurry is circulated in slurry circulation line 2 by first pump 6 in order to prevent the sedimentation of slurry particles.

During circulation, minute aggregated particles of silica contained within the slurry combine with each other in slurry circulation line 2 to form three-dimensional network structures having weak cohesive strength, tending to become large aggregated particles. However, the cohesion of these large aggregated particles can be broken up by irradiating the slurry inside circulation 7 line 2 with ultrasonic waves using ultrasonic wave oscillator 3, and the slurry particles thus again becomel minute particles. The slurry inside slurry circulation line 2 that has been broken down by ultrasonic waves is then conducted to piping 10, filtered by filter 4, and then supplied to CMP device 5.

The aggregation of slurry particles can be prevented by thus providing ultrasonic wave oscillator 3 in slurry circulation line 2 and irradiating ultrasonic waves onto the slurry inside slurry circulation line 2, As a result, slurry containing only minute particles ca be reliably supplied to CMP device 5. In addition, extraneous matter contained in the slurry can be eliminated by filter 4 and clean slurry can be supplied to CMP device 5. Furthermore, the filtering life of filter 4 can be improved because large aggregated particles are not contained in the slurry. Finally, ultrasonic wave oscillator 3 may also be incorporated a a part of slurry circulation line 2.

In this embodiment, the connection of piping 10 downstream in the direction of slurry flow from ultrasonic wave oscillator 3 allows CMP device 5 to be reliably supplied from circulation line 2 with slurry immediately after the slurry is subjected to irradiat.LO by ultrasonic waves, and the slurry therefore is free o aggregation and contains only minute particles.

8 Although filter 4 is provided in this embodiment, the provision of a filter is not absolutely necessary. In this invention, the aggregation of slurry particles is prevented and slurry containing minute particles can be supplied to CMP device 5 even if f ilter 4 is not provided. The cause of such defects as microscratches can thus be eliminated. In addition, the point of use of the slurry is not limited to CMP device 5, and the present invention may be adapted for other devices that use slurry.

According to the embodiment as described in detail in the foregoing explanation, slurry particles can be prevented f rom, forming aggregated particles by providing an ultrasonic wave oscillator in a slurry circulation line and subjecting the slurry inside the slurry circulation line to ultrasonic waves. Accordingly, a slurry containing minute particles can be reliably supplied to the point of use of the slurry, thereby suppressing the occurrence of such defects as microscratches.

While a preferred embodiment of the present invention has been described using specific terms, such description is for Illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the scope of the following claims.

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Claims

1 A slurry f eed device comprising: a slurry feed unit for supplying slurry; a slurry circulation line that is connected to an inlet and an outlet of the slurry feed unit for circulating the slurry; a first pump for moving and circulating slurry inside said slurry circulation line; an ultrasonic wave oscillator for irradiating slurry inside said slurry circulation line with ultrasonic waves; piping connecting said slurry circulation line and a point of use of the slurry; and a second pump for conducting said slurry from said slurry circulation line by way of said piping.

2. A slurry feed device according to claim 1 wherein a filter for filtering said slurry is provided in 'i said piping.

3. A slurry f eed device according to claim 1 or claim 2 wherein said piping is connected to said slurry circulation line downstream in the direction of f low of slurry from the position of connection of said ultrasonic wave oscillator.

4. A slurry feed device according to any one of claims 1 to 3 wherein the point of use of said slurry is a chemical-mechanical polishing device.

5. A slurry feed device according to any one of claims 1 to 4 provided with slurry, wherein said slurry contains silica particles.

6. A slurry feed device substantially as herein described with reference to Figure 2 of the drawings.

7. A chemical-mechanical polishing device fed with slurry provided by a slurry feed device in accordance with any preceding claim.

8. A semiconductor substrate polished by a chemical-mechanical polishing device in accordance with claim 7.

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