US20060121837A1

US20060121837A1 - Dressing method for polishing pad

Info

Publication number: US20060121837A1
Application number: US11/195,722
Authority: US
Inventors: Yoshiyuki Seike
Original assignee: Asahi Sunac Corp
Current assignee: Asahi Sunac Corp
Priority date: 2004-12-03
Filing date: 2005-08-03
Publication date: 2006-06-08
Also published as: JP2006159317A

Abstract

The present invention provides a dressing method for a polishing pad in a polishing apparatus which performs work with a work piece contacting a polishing pad while supplying a slurry, comprising the steps of performing dressing of the polishing pad by pressing a pad dresser against the polishing pad and performing dressing of the polishing pad by making a cleaning fluid fog drops each with a droplet grain size of 1 μm to 500 μm inclusive and spouting the fog drops to the polishing pad from a nozzle at a speed of 10 m/second to 500 m/second inclusive.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a dressing method for a polishing pad, and particularly related to a dressing method for a polishing pad which is preferably applicable to a polishing apparatus used for a planarizing process of an interlayer film and the like of a semiconductor integrated circuit.
2. Related Art
With reduction in a design rule of a semiconductor integrated circuit, a chemical mechanical polishing method (CMP) is frequently used for a planarizing process of interlayer films and the like. Polishing of a wafer by the CMP is performed by pressing the wafer against a rotating polishing pad at a predetermined pressure while rotating the wafer and supplying an abrasive slurry between the polishing pad and the wafer (for example, Japanese Patent Application Laid Open No. 2001-54854).
Such a polishing pad becomes clogged with a reaction product and polishing waste such as an abrasive grain as the polishing pad is used many times, and therefore, dressing is necessary. As dressing, a method for pressing a pad dresser constructed by a brush or a grindstone against the polishing pad, and microscopically roughing a surface of the polishing pad is generally adopted.
However, with the conventional dressing method, polishing waste which accumulates on a deep layer of the polishing pad cannot be removed. Besides, it is necessary to rub the polishing pad intensely with a brush or grindstone, and therefore, there is a disadvantage of damaging the polishing pad, and contaminating the polishing pad with dust occurring from the brush or grindstone. Further, a scratch due to shattering from an agglomerated abrasive and the pad dresser and the like sometimes occurs. Besides, in using the polishing pad, a residue and polishing waste of the abrasive remain in bores and grooves on a surface of the polishing pad, and a scratch sometimes occurs.
When a defect due to a polishing pad occurs as described above, replacement of the polishing pad is required, which causes serious problems in manufacture such as reduction in availability, reduction in yield, increase in cost of the material and the like.
As another dressing method for a polishing pad, there is proposed a method for performing dressing by spraying cleaning water at a high pressure to the polishing pad, but it has been pointed out that this method has the disadvantage of the polishing waste which accumulates on a deep layer of the polishing pad rising to a surface of the polishing pad by the cleaning water at a high pressure and contaminating the polishing pad.

SUMMARY OF THE INVENTION

The present invention is made in view of the above circumstances, and has its object to provide a dressing method for a polishing pad, which is capable of performing dressing without damaging or contaminating the polishing pad.
In order to achieve the above-described object, a first aspect of the present invention provides a dressing method for a polishing pad in a polishing apparatus which performs work with a work piece contacting a polishing pad while supplying a slurry, which is a dressing method for a polishing pad characterized by including the step of performing dressing of the polishing pad by pressing a pad dresser against the polishing pad, and performing dressing of the polishing pad by making a cleaning fluid fog drops each with a droplet grain size of 1 μm to 500 μm inclusive and spouting the fog drops to the polishing pad from a nozzle at a speed of 10 m/second to 500 m/second inclusive.
According to a first aspect of the present invention, in addition to the conventional dressing method by the pad dresser, dressing for the pad is performed by spouting the cleaning fluid to the polishing pad from the nozzle at a high speed, and therefore, polishing waste scraped out by the pad dresser can be immediately washed out. Besides, the polishing pad is washed out with the cleaning fluid, and therefore, the polishing pad does not have to be dressed harder than necessary with the pad dresser. Further, the size of the fog drop of the cleaning fluid which is collided against the polishing pad and the colliding speed are optimized so that the cleaning fluid is allowed to reach the deep layer of the polishing pad sufficiently, and therefore, the effect of the pad dresser striking the polishing pad to wash the polishing pad by pressing can be provided. Accordingly, the polishing waste accumulating on the deep layer of the polishing pad is allowed to rise to the surface layer of the polishing pad, and can be removed. In the present invention, the term “dressing” is used as an equivalent term for “conditioning”.
A second aspect of the present invention provides the dressing method of the first aspect for a polishing pad, wherein the cleaning fluid is pressurized to 1 MPa to 50 MPa inclusive to be spouted from the nozzle. By pressurizing the cleaning fluid like this, a favorable dressing effect by the cleaning fluid can be obtained.
A third aspect of the present invention provides the dressing method for a polishing pad of the first or the second aspect, wherein the pad dresser is a plate-shaped body with a number of diamond abrasives fixed on a surface of the plate-shaped body. By using the pad dresser constructed by a plate-shaped body with a number of diamond abrasives fixed on the surface like this, a favorable dressing effect is obtained. Note that such a pad dresser can be formed by electrodeposition of diamond or a metal bond (resin bond and vitrified bond may be suitable) diamond abrasive.
A fourth aspect of the present invention provides the dressing method for a polishing pad of any one of the first to the third aspects, wherein dressing of the polishing pad by the pad dresser is performed at the same time as polishing work, and dressing of the polishing pad by spout of the cleaning fluid is performed after the polishing work. When dressing by the pad dresser is performed in-situ and dressing by spout of the cleaning fluid is performed Ex-situ like this, down time by dressing can be minimized, and availability is enhanced.
A fifth aspect of the present invention provides the dressing method for a polishing pad according to any one of the first to the third aspects, wherein dressing of the polishing pad by the pad dresser is performed at the same time as polishing work, and dressing of the polishing pad by the pad dresser and dressing of the polishing pad by spout of the cleaning fluid are performed at the same time after the polishing work. When dressing by the pad dresser is performed in-situ, and dressing by the pad dresser and dressing by spout of the cleaning fluid are performed Ex-situ, down time by the dressing can be decreased, and availability is enhanced.
A sixth aspect of the present invention provides the dressing method for a polishing pad according to any one of the first to the third aspects, wherein dressing of the polishing pad by the pad dresser and dressing of the polishing pad by spout of the cleaning fluid are performed at the same time after polishing work. In the planarizing process of an interlayer film of Cu or the like, dressing in-situ is unsuitable, and by performing dressing by the pad dresser and dressing by spout of the cleaning fluid Ex-situ are performed at the same time, a favorable result is obtained.
A seventh aspect of the present invention provides the dressing method for a polishing pad according to any one of the first to the third aspects, wherein dressing of the polishing pad by the pad dresser is performed after polishing work, and thereafter, dressing of the polishing pad by the pad dresser and dressing of the polishing pad by spout of the cleaning fluid are performed at the same time. By performing dressing by the pad dresser Ex-situ as this, and thereafter, by performing dressing by the pad dresser and dressing by spout of the cleaning fluid at the same time, a favorable result is obtained.
An eighth aspect of the present invention provides the dressing method for a polishing pad according to any one of the first to the seventh aspects, wherein the pad dresser is provided with one through-hole or more, and the cleaning fluid is spouted from the one through-hole or more.
A ninth aspect of the present invention is the dressing method for a polishing pad of any one of the first to the seventh aspects, wherein the pad dresser is formed into a disk shape, and the cleaning fluid is spouted from an outer circumferential side of the pad dresser.
A tenth aspect of the present invention provides the dressing method for a polishing pad according to any one of the first to the seventh aspects, wherein the pad dresser is formed into an annular shape, and the cleaning fluid is spouted from an inner circumferential side of the pad dresser.
By adopting any one of the above-described constructions, a synergistic effect of combining two kinds of dressing methods is obtained.
An eleventh aspect of the present invention provides the dressing method for a polishing pad according to any one of the first to the tenth aspects, wherein dressing of the polishing pad is performed while the pad dresser and the nozzle are relatively moved with respect to the polishing pad. By adopting such a construction, the entire surface of the polishing pad can be dressed uniformly.
A twelfth aspect of the present invention provides a dressing method for a polishing pad in a polishing apparatus which performs work with a work piece contacting a polishing pad while supplying a slurry, which is a dressing method for a polishing pad characterized by including the step of performing dressing of the polishing pad by making a cleaning fluid fog drops each with a droplet grain size of 1 μm to 500 μm inclusive and spouting the fog drops to the polishing pad from a nozzle at a speed of 10 m/second to 500 m/second inclusive, and cleaning the polishing pad with a rinse fluid at a higher flow rate than the cleaning fluid.
A thirteenth aspect of the present invention provides a dressing method for a polishing pad in a polishing apparatus which performs work with a work piece contacting a polishing pad while supplying a slurry, which is a dressing method for a polishing pad characterized by including the step of performing dressing of the polishing pad by making a cleaning fluid fog drops each with a droplet grain size of 1 μm to 500 μm inclusive and spouting the fog drops to the polishing pad from a nozzle at a speed of 10 m/second to 500 m/second inclusive, and thereafter, cleaning the polishing pad with a rinse fluid of a larger flow rate than the cleaning fluid.
Even when the dressing by spout of the cleaning fluid is performed, and polishing waste accumulating on the deep layer of the polishing pad rises to the surface of the polishing pad, the polishing pad is cleaned with a rinse fluid at a high flow rate. Therefore, the disadvantage of contaminating the polishing pad does not occur, and a favorable dressing result is obtained.
A fourteenth aspect of the present invention provides the dressing method for a polishing pad of the twelfth or thirteenth aspect, wherein the leaning fluid is pressurized to 1 MPa to 50 Mpa inclusive to be spouted from the nozzle. By pressurizing the cleaning fluid like this, a favorable dressing effect by the cleaning fluid is obtained.
According to the present invention, in addition to the conventional dressing method by the pad dresser, dressing of the polishing pad is performed by spouting the cleaning fluid to the polishing pad from the nozzle at a high speed, and therefore, polishing waste scraped out by the pad dresser can be immediately washed away.
Besides, according to the present invention, even if the polishing waste accumulating on the deep layer of the polishing pad rises to the surface of the polishing pad by performing dressing by spout of the cleaning fluid, the polishing pad is washed with a rinse fluid at a high flow rate. Therefore, the disadvantage of contaminating the polishing pad does not occur, and a favorable dressing result is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a polishing apparatus to which a dressing method for a polishing pad of the present invention is applied;
FIG. 2 is a plan view of an essential part of the polishing apparatus in FIG. 1;
FIG. 3 is a sectional view of a nozzle;
FIG. 4 is a bottom view of the nozzle;
FIG. 5 is a plan view of an essential part of another polishing apparatus to which the dressing method for a polishing pad of the present invention is applied;
FIG. 6 is a plan view of an essential part of still another polishing apparatus to which the dressing method for a polishing pad of the present invention is applied;
FIG. 7 is a plan view of an essential part of yet another polishing apparatus to which the dressing method for a polishing pad of the present invention is applied;
FIG. 8 is a plan view of an essential part of still another polishing apparatus to which the dressing method for a polishing pad of the present invention is applied;
FIG. 9 is a plan view of a pad dresser;
FIG. 10 is a plan view of a pad dresser;
FIG. 11 is a plan view of a pad dresser; and
FIG. 12 is a plan view of a pad dresser.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment (first embodiment) of a dressing method for a polishing pad according to the present invention will be described in detail with reference to the attached drawings hereinafter. FIG. 1 is a front view of a polishing apparatus 10 to which the dressing method for a polishing pad of the present invention is applied, and FIG. 2 is a plan view of an essential part of the same.
As shown in FIGS. 1 and 2, the polishing apparatus 10 is mainly constructed by a polishing surface plate 52, a wafer holding head 51 which holds a work piece W, and a slurry supplying arm 53 which supplies a slurry (a solution in which an abrasive is dissolved, and mechanochemical abrasive is used in many cases).
The polishing surface plate 52 is formed into a disc shape, and a rotary shaft 54 is connected to a center of an undersurface of the polishing surface plate 52. The polishing surface plate 52 is rotated in the direction of the arrow in the drawing by driving a motor 56 connected to the rotary shaft 54. The polishing pad 50 is stuck onto a top surface of the polishing surface plate 52, so that a slurry is supplied onto the polishing pad 50 from a nozzle 53A at a tip end of the slurry supplying arm 53.
The wafer holding head 51 is a disk-shaped member which holds the work piece W on its undersurface, and a pressing force is transmitted to the wafer holding head 51 from a pressing device not shown by a pressing shaft 51A connected to a center of a top surface of the wafer holding head 51. The wafer holding head 51 rotates (free-running) in the direction of the arrow in the drawing, following the rotation of the polishing surface plate 52.
Next, a dressing device for the polishing pad that is a characteristic part of the present invention will be described. The dressing device for the polishing pad is composed of a pad dresser 60 and a nozzle 14. They are supported by a pump 20 through an arm 42 and a pipe 16.
Among them, the pad dresser 60 is a disk-shaped body with diamond abrasive grain fixed to its surface (undersurface). The pad dresser 60 is rotatably supported at the arm 40 through a shaft 60A connected to a center of its top surface. Accordingly, when the polishing surface plate 52 is rotationally driven with the pad dresser 60 pressed against the polishing pad 50, the pad dresser 60 also rotates (free-running).
The nozzle 14 is disposed at a position at a predetermined distance from a surface of the polishing pad 50. FIGS. 3 and 4 explain the nozzle 14, FIG. 3 is a sectional view of the nozzle 14, and FIG. 4 is a bottom view of the nozzle 14. The nozzle 14 is constructed by a nozzle chip 24 having a discharge port 22, and a nozzle case 26 in which the nozzle chip 24 is inserted. The discharge port 22 is longer than wide as shown in FIG. 4, and is formed into an elliptical shape with a central part extended toward a front (lower side in FIG. 3). As for the kind of nozzle 14, the nozzles of various kinds of specifications are adopted in accordance with the spout pattern.
The nozzle 14 is connected to the pump 20 through the pipe 16, and the pump 20 is connected to a tank 24 through a flexible hose 22. The cleaning water stored in the tank 24 is pressurized by the pump 20 and fed to the nozzle 14 so as to be spouted to the polishing pad 50. The pipe 16 is engaged with a spindle of a motor 30 through a sector rack 26 and a pinion gear 28. The pump 20 is placed on a table 32 through a rotary stage 18.
Accordingly, by normally or reversely rotating the motor 30, the nozzle 14 and the pad dresser 60 can be allowed to make swing motion in a lateral direction with the rotary stage 18 as the center of rotation. The swing motion of the nozzle 14 and the pad dresser 60 is controlled by a control unit not shown through the motor 30. FIG. 2 shows the swing motion, and the nozzle 14 and the pad dresser 60 can make swing motion as shown by the arrows d and e.
The pump 20 and the motor 30 are placed on the table 32. The table 32 is movable in the direction of the arrow a on a rail 36 provided on a base 34, and an end portion of the table 32 is connected to an air cylinder 38, which is supported on the base 34, through a rod 40. Accordingly, by operating the air cylinder 38, the nozzle 14 and the pad dresser 60 can be moved in the direction of the arrow a through the table 32 and the like.
Note that by changing the moving direction of the table 32 by changing the disposition of the rail 36, the air cylinder 38 and the like, the nozzle 14 and the pad dresser 60 may be horizontally moved in the direction perpendicular to an axis of the pipe 16.
As the cleaning water which is spouted from the nozzle 14, water (ultra pure water, primary pure water, running tap water and the like) is generally used, but these kinds of water doped with a chemical can be used.
Next, an operation of a dressing device (the pad dresser 60 and the nozzle 14) of the polishing pad constructed as above will be described. When a polishing operation is performed with the polishing pad 50 and dressing of the polishing pad 50 is required, a table moving mechanism (air cylinder 38 and the like) is operated and the table 32 is moved so that the nozzle 14 and the pad dresser 60 are located on a substantially center of the polishing pad 50. Then, the pad dresser 60 is pressed against the polishing pad 50 and the pump 24 is operated to spout the cleaning fluid from the nozzle 14.
The pad dresser 60 scrapes out polishing waste accumulating on the polishing pad 50 in an outer peripheral direction of the polishing pad 50. The cleaning fluid spouted from the nozzle 14 becomes fog drops each in the grain size of 1 μm to 500 μm inclusive, which collide against the polishing pad 50 at a speed of 10 m/s to 500 m/s inclusive.
Then, the cleaning fluid immediately washes the polishing waste scraped out by the pad dresser 60 in the outer peripheral direction of the polishing pad 50. The polishing waste scraped out is washed by the high-pressure cleaning fluid, and therefore, it is not necessary to rub the polishing pad 50 intensely with the pad dresser 60.
Accordingly, damage to the polishing pad 50 can be prevented, occurrence of dust by abrasion of the pad dresser 60 is suppressed to be able to prevent contamination of the polishing pad 50, and the occurrence of a scratch due to shattering and the like from an agglomerated abrasive and the pad dresser 60 can be prevented.
In the dressing device, by optimizing the size of the fog drop of the cleaning fluid and the colliding speed, the cleaning fluid is allowed to sufficiently reach a deep layer of the polishing pad 50, and therefore, a clean cleaning fluid is always fed into the polishing pad 50. Accordingly, by rotating (free-running) the pad dresser 60 and pressing the polishing pad 50 with the pad dresser 60, the effect of washing the polishing pad 50 by pressing is provided. Thereby, the polishing waste accumulating on the deep layer of the polishing pad 50 is allowed to rise to the surface layer of the polishing pad 50 and can be removed.
Then, as described above, while rotating the pad dresser 60 and spouting the cleaning fluid from the nozzle 14, the polishing pad 50 (polishing surface plate 52) is rotated in the arrow direction in FIG. 2. Further, dressing is performed while the arm 42 is swung in the directions of the arrows d and e in FIG. 2, and thereby, dressing is fully performed for the entire surface of the polishing pad 50 while the polishing waste on the polishing pad 50 is swept out in the outer peripheral direction of the polishing pad 50.
The grain size of the fog drop of the cleaning fluid which is collided against the polishing pad 50 is preferably from 1 μm to 500 μm inclusive, more preferably from 1 μm to 300 μm inclusive, and still more preferably from 1 μm to 100 μm inclusive.
A too small fog drop easily loses kinetic energy by resistance of air and collision with the polishing pad 50, a too large fog drop cannot enter a hole of the polishing pad 50, and therefore, neither of them can reach the deep layer of the polishing pad 50.
The speed at which the fog drops of the cleaning fluid collide against the polishing pad 50 is preferably from 10 m/s to 500 m/s inclusive, and more preferably from 30 m/s to 150 m/s inclusive. If the colliding speed of the fog drops is too low, sufficient kinetic energy to reach the deep layer of the polishing pad 50 is not obtained, and if the colliding speed of the fog drops is too high, there arises the possibility of damaging the polishing pad 50.
In order to realize the size of the fog drops of the cleaning fluid and the colliding speed described above, in the case of the discharge port of the nozzle 14 in the elliptic shape with the short diameter of 400 μm and the long diameter of 600 μm, it is preferable to supply the cleaning fluid to the nozzle 14 at the pressure of 1 MPa to 50 MPa inclusive, and it is more preferable to supply the cleaning fluid at the pressure of 10 MPa to 30 MPa inclusive.
In the operation of the dressing device for the polishing pad as described above, various kinds of variations are conceivable for the combination of the polishing work and dressing in accordance with the material quality of the polished object (work piece W, a pattern on a wafer and the like), the kind of the polishing pad 50, composition of the abrasive slurry and the like. The variations will be described hereinafter.
1) A method for performing dressing of the polishing pad 50 by the pad dresser 60 at the same time as polishing work, and performing dressing of the polishing pad 50 by spouting the cleaning fluid from the nozzle 14 after the polishing work.
If the dressing by the pad dresser 60 is performed in-situ and the dressing by spout of the cleaning fluid is performed Ex-situ, downtime by the dressing can be minimized, and the availability is enhanced.
Note that the dressing may not performed for each treatment of each work piece W (wafer), and a method for performing one dressing every 10-cassette treatment of the work pieces W (250 work pieces) may be adopted (the same applies to the following variations (variations 2 to 6)), for example.
2) A method for performing dressing of the polishing pad 50 by the pad dresser 60 at the same time as polishing work, and performing dressing of the polishing pad 50 by spouting the cleaning fluid from the nozzle 14 at the same time as the dressing of the polishing pad 50 by the pad dresser 60 after the polishing work.
As described above, when the dressing by the pad dresser 60 is performed in-situ, and the dressing by the pad dresser 60 and the dressing by spout of the cleaning fluid are performed Ex-situ, downtime by the dressing can be also decreased, and availability is enhanced.
3) A method for performing dressing of the polishing pad 50 by spouting the cleaning fluid from the nozzle 14 at the same time as dressing of the polishing pad 50 by the pad dresser 60, after polishing work.
In the planarizing process of the inter-layer film of Cu or the like, dressing in-situ is unsuitable, and a favorable result is obtained by performing the dressing by the pad dresser 60 and the dressing by spout of the cleaning fluid Ex-situ at the same time.
4) A method for performing dressing of the polishing pad 50 by the pad dresser 60 after polishing work, and thereafter, performing dressing of the polishing pad 50 by spouting the cleaning fluid from the nozzle 14 at the same time as the dressing of the polishing pad 50 by the pad dresser 60.
A favorable result is also obtained by performing the dressing by the pad dresser 60 Ex-situ, and thereafter, performing the dressing by the pad dresser 60 and the dressing by the spout of the cleaning fluid at the same time.
Next, another embodiment (second embodiment) of a dressing method for a polishing pad according to the present invention will be described in detail. FIG. 5 is a plan view of an essential part of another polishing apparatus to which the dressing method for a polishing pad of the present invention is applied, and corresponds to FIG. 2 of the first embodiment. The same and similar members as and to those in FIGS. 1 and 2 are assigned with the same reference numerals and characters, and the detailed explanation will be omitted.
In this embodiment, the different point from the first embodiment is the construction of the dressing device (pad dresser 60 and the nozzle 14) and the construction of the slurry supplying arm 53.
Concerning the dressing device, the pad dresser 60 is rotatably supported at a tip end portion of the arm 42 in this embodiment as in the first embodiment, but the nozzle 14 is fixed to a side surface of the arm 42 unlike the first embodiment. The cleaning fluid is supplied to the nozzle 14 through a supply pipe 14A by the pump 20 (see FIG. 1).
Unlike the first embodiment, the arm 42 is rotated around a rotational center 42A by a rotating device not shown (the same thing also applies to the following third to fifth embodiments).
The above construction of the dressing device is different from the first embodiment, but the basic operation is substantially the same as in the first embodiment. As for the operation of the dressing device (pad dresser 60 and the nozzle 14) of the polishing pad constructed as above is substantially the same as the first embodiment, and therefore, the explanation will be omitted.
When the pad dresser 60 is not used as in the case of the other variations (variations 5) and 6)) of the combination of the later-described polishing work and dressing, the pad dresser 60 is capable of retreating above.
The nozzle 53A for slurry supply is fixed to a tip end portion of the slurry supplying arm 53 as in the first embodiment, but in this embodiment, in addition to this, six rinse fluid supplying nozzles 55 are fixed to the undersurface of the slurry supplying arm 53 at predetermined spaces.
According to the construction of the above slurry supplying arm 53, the rinse fluid can be supplied to a wide range from the center to the outer periphery on the polishing pad 50.
An operation of the slurry supplying arm 53 constructed as above will be described. On polishing work, the slurry supplying arm 53 is fixed to the position in FIG. 5, and a slurry is supplied onto the polishing pad 50 by the nozzle 53A for slurry supply at the tip end. At this time, there is no supply of a rinse fluid from the rinse fluid supplying nozzles 55.
Meanwhile, on dressing by the nozzle 14, or after dressing by the nozzle 14, the rinse fluid is supplied onto the polishing pad 50 by the rinse fluid supplying nozzles 55, and polishing waste, which is allowed to rise to the surface layer of the polishing pad 50 from the deep layer of the polishing pad 50 by the nozzle 14, is washed away in an outer peripheral direction of the polishing pad 50, and the entire surface of the polishing pad 50 is fully dressed.
In this case, the polishing pad 50 (polishing surface plate 52) rotates, and therefore, even if the slurry supplying arm 53 is fixed to the position in FIG. 5, the entire surface of the polishing pad 50 can be fully dressed. On dressing, supply of slurry onto the polishing pad 50 from the nozzle 53A is not performed.
As the rinse fluid which is supplied from the rinse fluid supplying nozzles 55, water (ultra pure water, primary pure water, running tap water and the like) is generally used, but these kinds of water to which a chemical agent is added can be used. As for a supply flow rate of the rinse fluid, a larger flow rate than the flow rate of the cleaning fluid which is spouted from the nozzle 14 is required. By making the supply flow rate of the rinse fluid higher than the flow rate of the cleaning fluid like this, the polishing waste which is allowed to rise to the surface layer of the polishing pad 50 can be completely washed away in the outer peripheral direction of the polishing pad 50.
When the flow rate of the cleaning fluid which is spouted from the nozzle 14 is set at, for example, 1 litter/minute, it is preferable to set the supply flow rate of rinse fluid at 1 to 1000 litter/minute, and it is more preferable to set it at 10 to 100 little/minute. The optimal flow rate of the cleaning fluid changes in accordance with the diameter of the polishing pad 50 and the number of nozzles 14. Spout of the rinse fluid which is supplied from the rinse fluid supplying nozzles 55 may be simultaneous spout or may be sequential spout.
Next, variations of the combination of polishing work and dressing according to the construction of the second embodiment will be described.
5) After polishing work, dressing of the polishing pad 50 is performed by spouting the cleaning fluid to the polishing pad 50 from the nozzle 14, and the polishing pad 50 is cleaned by supplying the rinse fluid at a higher flow rate than the cleaning fluid onto the polishing pad 50 from the rinse fluid supplying nozzles 55.
Even when polishing waste accumulating on the deep layer of the polishing pad 50 rises to the surface of the polishing pad 50 by performing dressing by spout of the cleaning fluid as above, the polishing pad 50 is cleaned with the rinse fluid at a high flow rate, and therefore, a disadvantage of contaminating the polishing pad 50 does not occur, thus making it possible to obtain a favorable dressing result.
6) After polishing work, dressing of the polishing pad 50 is performed by spouting the cleaning fluid to the polishing pad 50 from the nozzle 14, and thereafter, the polishing pad 50 is cleaned by supplying the rinse fluid at a higher flow rate than the cleaning fluid onto the polishing pad 50 by the rinse fluid supplying nozzles 55.
Even when polishing waste accumulating on the deep layer of the polishing pad 50 rises to the surface of the polishing pad 50 by performing dressing by spout of the cleaning fluid as above, the polishing pad 50 is cleaned with the rinse fluid at a high flow rate, and therefore, a disadvantage of contaminating the polishing pad 50 does not occur, thus making it possible to obtain a favorable dressing result.
Next, another embodiment (third embodiment) of the dressing method for a polishing pad according to the present invention will be described in detail. FIG. 6 is a plan view of an essential part of still another polishing apparatus to which the dressing method for a polishing pad of the present invention is applied, and corresponds to FIG. 2 of the first embodiment and FIG. 5 of the second embodiment. The same and similar members as and to FIGS. 1, 2 and 5 are assigned with the same reference numerals and characters, and the detailed explanation thereof will be omitted.
In this embodiment, the different point from the second embodiment is the construction of the nozzle 14 of the dressing device. Namely, the third embodiment is the same as the second embodiment in the point that the nozzle 14 is placed at the side surface of the arm 42, but the nozzle 14 is supported slidably in the longitudinal direction with respect to the arm 42 through a nozzle guide 14B. Supply of the cleaning fluid to the nozzle 14 is performed by the pump 20 (see FIG. 1) through the supply pipe 14A.
An operation of the third embodiment corresponding to the above construction will be described. On dressing by the dressing device, the arm 42 moves to a position of a phantom line (two-dot-chain line) from a retreat position shown in FIG. 6, and the dressing of the polishing pad 50 by any one or both of the pad dresser 60 and the nozzle 14 is performed.
At this time, the nozzle 14 can be slid in the longitudinal direction with the position of the pad dresser 60 fixed. Therefore, dressing of the substantially entire surface of the polishing pad 50 can be performed by spouting the cleaning fluid to the polishing pad 50 from the nozzle 14 with the position of the pad dresser 60 fixed.
Next, another embodiment (fourth embodiment) of the dressing method of the polishing pad according to the present invention will be described in detail. FIG. 7 is a plan view of an essential part of still another polishing apparatus to which the dressing method of the polishing pad of the present invention is applied, and corresponds to FIG. 2 of the first embodiment, FIG. 5 of the second embodiment, and FIG. 6 of the third embodiment. The same and similar members as those in FIGS. 1, 2, 5 and 6 are given the same reference numerals and characters, and the detailed explanation thereof will be omitted.
In this embodiment, the different point from the first embodiment is the construction of the nozzle 14 of the dressing device. Namely, the nozzle 14 is placed in the vicinity of a tip end portion of the slurry supplying arm 53 (inner side from the nozzle 53A for slurry supply) instead of being placed at the arm 42. Supply of the cleaning fluid to the nozzle 14 is performed by the pump 20 (see FIG. 1) through the supply pipe 14A.
An operation of the fourth embodiment corresponding to the above construction will be described. On the occasion of dressing by the dressing device, the arm 42 moves to the position of the phantom line (two-dot-chain line) from the retreat position shown in FIG. 7, and dressing of the polishing pad 50 by the pad dresser 60 is performed.
When dressing of the polishing pad 50 is performed by spouting the cleaning fluid to the polishing pad 50 from the nozzle 14 at the same time as the dressing of the polishing pad 50 by the pad dresser 60, the slurry supplying arm 53 is swung with the position of the pad dresser 60 (the position of the arm 42) fixed, whereby the cleaning fluid is spouted to the polishing pad 50 from the nozzle 14 to be able to perform dressing of the substantially entire surface of the polishing pad 50.
Next, another embodiment (fifth embodiment) of the dressing method for the polishing pad according to the present invention will be described in detail. FIG. 8 is a plan view of an essential part of still another polishing apparatus to which the dressing method for the polishing pad of the present invention is applied, and corresponds to FIG. 2 of the first embodiment, FIG. 5 of the second embodiment, FIG. 6 of the third embodiment and FIG. 7 of the fourth embodiment. The same and similar members as and to those in FIGS. 1, 2, 5, 6 and 7 are assigned with the same reference numerals and characters, and the detailed explanation thereof will be omitted.
In this embodiment, the different point from the first embodiment is the construction of the pad dresser 60 and the construction of the nozzle 14 of the dressing device. Namely, the nozzle 14 is placed at a rear surface of the pad dresser 60, so that the cleaning fluid is spouted to the polishing pad 50 from a through-hole provided at the pad dresser 60 or an inner and outer circumferences of the pad dresser 60. Supply of the cleaning fluid to the nozzle 14 is performed from the pump 20 (see FIG. 1) through the supply pipe 14A.
Hereinafter, the details of the pad dresser 60 will be described. FIGS. 9 to 12 are plane views (bottom views) of the pad dresser 60. The pad dresser 60 shown in FIG. 9 is disk-shaped and is provided with a through-hole 60A at a central part, and the cleaning fluid is spouted from the through-hole 60A.
The pad dresser 60 shown in FIG. 10 is disk-shaped and is provided with a plurality of (eight in the drawing) through-holes 60B to be distributed on the entire surface, and the cleaning fluid is spouted from the through-holes 60B.
The pad dresser 60 shown in FIG. 11 is disk-shaped and is provided with a ring-shaped member 61 at an outer peripheral side of this, and the cleaning fluid is spouted from a plurality of (four in the drawing) through-holes 61A provided in the ring-shaped member 61.
The pad dresser 60 shown in FIG. 12 is annular and is provided with a ring-shaped member 63 at an inner peripheral side of this, and the cleaning fluid is spouted from a plurality of (four in the drawing) through-holes 63A provided in the ring-shaped member 63.
By adopting any one of the constructions shown in FIG. 9 to FIG. 12 as described above, a synergistic effect of combination of two kinds of dressing methods such as the pad dresser 60 and the nozzle 14 is obtained.
Namely, in each of the constructions, the pad dresser 60 and the nozzle 14 are adjacently placed, and therefore, foreign matters such as polishing waste scraped out from the polishing pad 50 by the pad dresser 60 can be immediately washed away by the cleaning fluid spouted from the nozzle 14.
Each of the embodiments of the dressing method for the polishing pad according to the present invention is described thus far, but the present invention is not limited to the above described embodiments, and various kinds of modes can be adopted.
For example, in this embodiment, the wafer holding head 51 which holds the work piece W on the undersurface rotates (free-running) in the direction of the arrow in each drawing, following the rotation of the polishing surface plate 52, but the wafer holding head 51 can be provided with a unique driving device (motor or the like).
The polishing apparatus 10 shown in this embodiment is of a type of holding the work piece W with the wafer holding head 51, but the present invention can be favorably applied to a polishing apparatus of a type in which the work piece W is placed in a carrier placed at an inner side of the ring-shaped member placed on the polishing pad 50, a so-called ring polisher.
Further, in this embodiment, a polishing pad (for example, a polyurethane pad) of a semiconductor wafer polishing apparatus is cited as an example of the target of dressing, but the target of dressing is not limited to this, and the present invention can be also favorably applied to dressing of a polishing puff, a porous grindstone and the like of other polishing apparatuses.

Claims

1. A dressing method for a polishing pad in a polishing apparatus which performs work with a work piece contacting a polishing pad while supplying a slurry, comprising the steps of:

performing dressing of the polishing pad by pressing a pad dresser against the polishing pad; and

performing dressing of the polishing pad by making a cleaning fluid fog drops each with a droplet grain size of 1 μm to 500 μm inclusive and spouting the fog drops to the polishing pad from a nozzle at a speed of 10 m/second to 500 m/second inclusive.

2. The dressing method for a polishing pad according to claim 1, wherein the cleaning fluid is pressurized to 1 MPa to 50 MPa inclusive to be spouted from the nozzle.

3. The dressing method for a polishing pad according to claim 1, wherein the pad dresser is a plate-shaped body with a number of diamond abrasives fixed on a surface of the plate-shaped body.

4. The dressing method for a polishing pad according to claim 2, wherein the pad dresser is a plate-shaped body with a number of diamond abrasives fixed on a surface of the plate-shaped body.

5. The dressing method for a polishing pad according to claim 1, wherein dressing of the polishing pad by the pad dresser is performed at the same time as polishing work, and dressing of the polishing pad by spout of the cleaning fluid is performed after the polishing work.

6. The dressing method for a polishing pad according to claim 2, wherein dressing of the polishing pad by the pad dresser is performed at the same time as polishing work, and dressing of the polishing pad by spout of the cleaning fluid is performed after the polishing work.

7. The dressing method for a polishing pad according to claim 3, wherein dressing of the polishing pad by the pad dresser is performed at the same time as polishing work, and dressing of the polishing pad by spout of the cleaning fluid is performed after the polishing work.

8. The dressing method for a polishing pad according to claim 4, wherein dressing of the polishing pad by the pad dresser is performed at the same time as polishing work, and dressing of the polishing pad by spout of the cleaning fluid is performed after the polishing work.

9. The dressing method for a polishing pad according to claim 1, wherein dressing of the polishing pad by the pad dresser is performed at the same time as polishing work, and dressing of the polishing pad by the pad dresser and dressing of the polishing pad by spout of the cleaning fluid are performed at the same time after the polishing work.

10. The dressing method for a polishing pad according to claim 1, wherein dressing of the polishing pad by the pad dresser and dressing of the polishing pad by spout of the cleaning fluid are performed at the same time after polishing work.

11. The dressing method for a polishing pad according to claim 1, wherein dressing of the polishing pad by the pad dresser is performed after polishing work, and thereafter, dressing of the polishing pad by the pad dresser and dressing of the polishing pad by spout of the cleaning fluid are performed at the same time.

12. The dressing method for a polishing pad according to claim 1, wherein the pad dresser is provided with one through-hole or more, and the cleaning fluid is spouted from the one through-hole or more.

13. The dressing method for a polishing pad according to claim 1, wherein the pad dresser is formed into a disk shape, and the cleaning fluid is spouted from an outer circumferential side of the pad dresser.

14. The dressing method for a polishing pad according to claim 1, wherein the pad dresser is formed into an annular shape, and the cleaning fluid is spouted from an inner circumferential side of the pad dresser.

15. The dressing method for a polishing pad according to claim 1, wherein dressing of the polishing pad is performed while the pad dresser and the nozzle are relatively moved with respect to the polishing pad.

16. A dressing method for a polishing pad in a polishing apparatus which performs work with a work piece contacting a polishing pad while supplying a slurry, comprising the steps of:

performing dressing of the polishing pad by making a cleaning fluid fog drops each with a droplet grain size of 1 μm to 500 μm inclusive and spouting the fog drops to the polishing pad from a nozzle at a speed of 10 m/second to 500 m/second inclusive; and

cleaning the polishing pad with a rinse fluid at a higher flow rate than the cleaning fluid.

17. A dressing method for a polishing pad in a polishing apparatus which performs work with a work piece contacting a polishing pad while supplying a slurry, comprising the steps of:

thereafter, cleaning the polishing pad with a rinse fluid at a higher flow rate than the cleaning fluid.

18. The dressing method for a polishing pad according to claim 16 wherein the cleaning fluid is pressurized to 1 MPa to 50 MPa inclusive to be spouted from the nozzle.

19. The dressing method for a polishing pad according to claim 17 wherein the cleaning fluid is pressurized to 1 MPa to 50 MPa inclusive to be spouted from the nozzle.