Non-contact pad cleaning device

Abstract

To provide a non-contact pad cleaning device which can remove foreign objects from minute holes formed on a polishing surface of a polishing pad.SOLUTION: A non-contact pad cleaning device includes: a rotary table 5 which rotates a polishing pad 2; a plurality of two-fluid nozzles 8 disposed above the polishing pad 2; and a liquid supply line 61 and a gas supply line 65 connected to the two-fluid nozzles 8. The two-fluid nozzles 8 are arranged along a radial direction of the polishing pad 2. When viewed from a direction perpendicular to a polishing surface 2a of the polishing pad 2, jet ports 8a of the two-fluid nozzles 8 obliquely incline relative to a reference line RL extending in the radial direction of the polishing pad 2.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a non-contact pad cleaning device for cleaning the polishing surface of a polishing pad used for polishing workpieces such as wafers, substrates, and wiring panels with a fluid.

Background Art

[0002] A polishing device is a device for polishing workpieces such as wafers, substrates, and wiring panels used in the manufacture of semiconductor devices. The workpiece is polished on its surface by being brought into sliding contact with the polishing surface of a polishing pad in the presence of a slurry. In order to maintain the polishing performance of the polishing pad, dressing of the polishing surface of the polishing pad is performed using a dresser. Specifically, the dresser regenerates the polishing surface of the polishing pad by bringing a dressing surface on which abrasive grains such as diamond particles are fixed into sliding contact with the polishing surface of the polishing pad, thereby slightly shaving off the polishing surface of the polishing pad.

[0003] Microscopic holes are formed in the polishing surface of the polishing pad. Foreign substances such as polishing debris of the workpiece, abrasive grains contained in the slurry, and shaving debris of the polishing pad accumulate in these holes. Therefore, in order to remove the foreign substances from the holes, while rotating the polishing pad, a jet of pure water is applied to the polishing surface from an atomizer, and the foreign substances are washed away from the polishing pad with the pure water.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the polishing surface of the polishing pad is wide, foreign matter once removed from the holes by the jet of pure water from the atomizer may adhere to the polishing surface again. In addition, dressing of the polishing pad by the dresser slightly scrapes the polishing surface of the polishing pad, so that foreign matter deposited in the holes of the polishing pad cannot be completely removed. As a result, the workpiece is polished with foreign matter remaining on the polishing pad. The foreign matter remaining on the polishing pad causes scratches on the workpiece. In addition, foreign matter adhering to the workpiece may contaminate the cleaning tool used in the cleaning process performed after the polishing process. Furthermore, foreign matter adhering to the workpiece may also cause defects in the semiconductor device.

[0006] Therefore, the present invention provides a non-contact pad cleaning device capable of removing foreign matter from minute holes formed in the polishing surface of a polishing pad.

Means for Solving the Problems

[0007] In one aspect, there is provided a non-contact pad cleaning device for non-contact cleaning of a polishing surface of a polishing pad for polishing a workpiece, including a rotating table for rotating the polishing pad, a plurality of two-fluid nozzles disposed above the polishing pad, and a liquid supply line and a gas supply line connected to the plurality of two-fluid nozzles. The plurality of two-fluid nozzles are arranged along the radial direction of the polishing pad, and when viewed from a direction perpendicular to the polishing surface of the polishing pad, the ejection ports of the plurality of two-fluid nozzles are inclined obliquely with respect to a reference line extending in the radial direction of the polishing pad.

[0008] In one aspect, when viewed from a direction perpendicular to the polishing surface of the polishing pad, the ejection ports of the plurality of two-fluid nozzles are inclined in the same direction as the rotation direction of the polishing pad. In one aspect, when viewed from a direction perpendicular to the polishing surface of the polishing pad, the ejection ports of the plurality of two-fluid nozzles are on the reference line. In one aspect, when viewed from a direction perpendicular to the polishing surface of the polishing pad, the inclination angle of the ejection ports of the plurality of two-fluid nozzles with respect to the reference line increases according to the distance of each two-fluid nozzle from the center of the polishing pad. In one aspect, when viewed from a direction perpendicular to the polishing surface of the polishing pad, the distance of the ejection ports of the plurality of two-fluid nozzles from the reference line increases according to the distance of each two-fluid nozzle from the center of the polishing pad, and the distance of the ejection ports of each two-fluid nozzle from the reference line is the distance toward the downstream side from the reference line in the rotation direction of the polishing pad.

[0009] In one aspect, the non-contact pad cleaning device further includes a fine bubble generator connected to the liquid supply line. In one aspect, the non-contact pad cleaning device further includes a liquid heating device connected to the liquid supply line and heating the liquid flowing through the liquid supply line. In one aspect, the non-contact pad cleaning device further includes a pad cleaning nozzle that forms a jet of liquid discharge fluid for guiding the liquid contained in the two-fluid on the polishing surface of the polishing pad to the outer periphery of the polishing pad. In one aspect, the non-contact pad cleaning device further includes a liquid discharge fluid line that supplies liquid discharge fluid to the pad cleaning nozzle and a fine bubble generator connected to the liquid discharge fluid line. In one aspect, the pad cleaning nozzle is disposed downstream of the plurality of two-fluid nozzles in the rotation direction of the polishing pad.

[0010] In one aspect, the plurality of two-fluid nozzles include center-side two-fluid nozzles located on the center side of the polishing pad and outer-periphery-side two-fluid nozzles located on the outer periphery side of the polishing pad, and the distance of the ejection ports of the outer-periphery-side two-fluid nozzles from the polishing surface is smaller than the distance of the ejection ports of the center-side two-fluid nozzles from the polishing surface. In one aspect, the plurality of two-fluid nozzles include a central two-fluid nozzle located on the central side of the polishing pad and an outer peripheral two-fluid nozzle located on the outer peripheral side of the polishing pad, and the distance from the ejection port of the outer peripheral two-fluid nozzle to the polishing surface is greater than the distance from the ejection port of the central two-fluid nozzle to the polishing surface. In one aspect, the liquid supply line has a plurality of branched liquid lines respectively connected to the plurality of two-fluid nozzles, the non-contact pad cleaning device further includes a plurality of liquid flow rate control valves respectively connected to the plurality of branched liquid lines, and an operation control unit that independently controls the operations of the plurality of liquid flow rate control valves. The plurality of two-fluid nozzles include a central two-fluid nozzle located on the central side of the polishing pad and an outer peripheral two-fluid nozzle located on the outer peripheral side of the polishing pad. The operation control unit is configured to control the operations of the plurality of liquid flow rate control valves such that the flow rate of the liquid supplied to the outer peripheral two-fluid nozzle is higher than the flow rate of the liquid supplied to the central two-fluid nozzle. In one aspect, the liquid supply line has a plurality of branched liquid lines respectively connected to the plurality of two-fluid nozzles, the non-contact pad cleaning device further includes a plurality of liquid flow rate control valves respectively connected to the plurality of branched liquid lines, and an operation control unit that independently controls the operations of the plurality of liquid flow rate control valves. The plurality of two-fluid nozzles include a central two-fluid nozzle located on the central side of the polishing pad and an outer peripheral two-fluid nozzle located on the outer peripheral side of the polishing pad. The operation control unit is configured to control the operations of the plurality of liquid flow rate control valves such that the flow rate of the liquid supplied to the central two-fluid nozzle is higher than the flow rate of the liquid supplied to the outer peripheral two-fluid nozzle.

[0011] In one aspect, the gas supply line has a plurality of branched gas lines respectively connected to the plurality of two-fluid nozzles, and the non-contact pad cleaning device further includes a plurality of gas flow control valves respectively connected to the plurality of branched gas lines and an operation control unit that independently controls the operations of the plurality of gas flow control valves. The plurality of two-fluid nozzles include a central two-fluid nozzle located on the central side of the polishing pad and an outer peripheral two-fluid nozzle located on the outer peripheral side of the polishing pad. The operation control unit is configured to control the operations of the plurality of gas flow control valves such that the flow rate of the gas supplied to the outer peripheral two-fluid nozzle is higher than the flow rate of the gas supplied to the central two-fluid nozzle. In one aspect, the gas supply line has a plurality of branched gas lines respectively connected to the plurality of two-fluid nozzles, and the non-contact pad cleaning device further includes a plurality of gas flow control valves respectively connected to the plurality of branched gas lines and an operation control unit that independently controls the operations of the plurality of gas flow control valves. The plurality of two-fluid nozzles include a central two-fluid nozzle located on the central side of the polishing pad and an outer peripheral two-fluid nozzle located on the outer peripheral side of the polishing pad. The operation control unit is configured to control the operations of the plurality of gas flow control valves such that the flow rate of the gas supplied to the central two-fluid nozzle is higher than the flow rate of the gas supplied to the outer peripheral two-fluid nozzle. In one aspect, the gas supply line has a plurality of branched gas lines respectively connected to the plurality of two-fluid nozzles, and the non-contact pad cleaning device further includes a plurality of pressure regulators respectively connected to the plurality of branched gas lines and an operation control unit that independently controls the operations of the plurality of pressure regulators. The plurality of two-fluid nozzles include a central two-fluid nozzle located on the central side of the polishing pad and an outer peripheral two-fluid nozzle located on the outer peripheral side of the polishing pad. The operation control unit is configured to control the operations of the plurality of pressure regulators such that the pressure of the gas supplied to the outer peripheral two-fluid nozzle is higher than the pressure of the gas supplied to the central two-fluid nozzle.

[0012] In one aspect, there is provided a non-contact pad cleaning device for cleaning a polishing surface of a polishing pad for polishing a workpiece without contact, the non-contact pad cleaning device including a rotating table for rotating the polishing pad, a two-fluid nozzle arranged above the polishing pad, a liquid supply line and a gas supply line connected to the two-fluid nozzle, and a nozzle swing mechanism for swinging the two-fluid nozzle along the polishing surface, wherein an ejection port of the two-fluid nozzle faces outward in a radial direction of the polishing pad.

[0013] In one aspect, the non-contact pad cleaning device further includes a fine bubble generator connected to the liquid supply line. In one aspect, the non-contact pad cleaning device further includes a liquid heating device connected to the liquid supply line and configured to heat a liquid flowing through the liquid supply line. In one aspect, the non-contact pad cleaning device further includes a pad cleaning nozzle configured to form a jet flow of a liquid discharge fluid for guiding a liquid contained in the two-fluid on the polishing surface of the polishing pad to an outer periphery of the polishing pad. In one aspect, the non-contact pad cleaning device further includes a liquid discharge fluid line for supplying a liquid discharge fluid to the pad cleaning nozzle, and a fine bubble generator connected to the liquid discharge fluid line. In one aspect, the pad cleaning nozzle is arranged downstream of the two-fluid nozzle in a rotation direction of the polishing pad.

Advantages of the Invention

[0014] Since ejection ports of a plurality of two-fluid nozzles are inclined obliquely with respect to a reference line extending in a radial direction of the polishing pad, two-fluid jets ejected from the plurality of ejection ports do not collide with each other and do not impede flows of liquids on the polishing surface from each other. The liquid contained in the two-fluid jets flows outward by a centrifugal force generated by the rotating polishing pad, and foreign matters such as polishing debris can be washed away from the polishing pad.

[0015] Since the ejection ports of the plurality of two-fluid nozzles face outward in the radial direction of the polishing pad, the two-fluid jets ejected from the plurality of ejection ports form a flow of liquid that moves outward on the polishing surface. This outward flow of the liquid is accelerated by the centrifugal force generated by the rotating polishing pad, and foreign matter such as polishing debris can be washed away from the polishing pad.

Brief Description of the Drawings

[0016]

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[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of a polishing apparatus including a non-contact pad cleaning device. The polishing apparatus is an apparatus for chemically mechanically polishing a wafer W, which is an example of a workpiece used in the manufacture of semiconductor devices. As shown in FIG. 1, this polishing apparatus includes a rotary table 5 that supports a polishing pad 2 having a polishing surface 2a, a polishing head 7 that presses the wafer W against the polishing surface 2a, a polishing liquid supply nozzle 10 that supplies a polishing liquid (for example, a slurry containing abrasive grains) to the polishing surface 2a, and a plurality of two-fluid nozzles 8 and a plurality of pad cleaning nozzles 9 that clean the polishing surface 2a of the polishing pad 2. The plurality of two-fluid nozzles 8 and the plurality of pad cleaning nozzles 9 are arranged above the polishing surface 2a of the polishing pad 2 and face the polishing surface 2a.

[0018] The polishing head 7 is configured to hold the wafer W on its lower surface. The wafer W has a film to be polished. In the following embodiments, a wafer is used as an example of the workpiece, but the workpiece is not limited to a wafer and may be a circular substrate, a rectangular substrate, a panel, etc. used in the manufacture of semiconductor devices.

[0019] The polishing apparatus further includes a support shaft 14, a polishing head swing arm 16 connected to the upper end of the support shaft 14, and a polishing head shaft 18 rotatably supported at the free end of the polishing head swing arm 16. The polishing head 7 is fixed to the lower end of the polishing head shaft 18. A polishing head rotation mechanism (not shown) including an electric motor or the like is disposed within the polishing head swing arm 16. This polishing head rotation mechanism is connected to the polishing head shaft 18 and is configured to rotate the polishing head shaft 18 and the polishing head 7 in the direction indicated by the arrow.

[0020] The polishing head shaft 18 is connected to a polishing head lifting mechanism (including a ball screw mechanism or the like) not shown. This polishing head lifting mechanism is configured to move the polishing head shaft 18 relatively up and down with respect to the polishing head swing arm 16. Due to the up and down movement of the polishing head shaft 18, the polishing head 7 can move relatively up and down with respect to the polishing head swing arm 16 and the rotary table 5 as indicated by the arrow.

[0021] The polishing apparatus further includes a table rotation motor 21 that rotates the polishing pad 2 and the rotary table 5 about their axes. The table rotation motor 21 is disposed below the rotary table 5, and the rotary table 5 is connected to the table rotation motor 21 via a table shaft 5a. The rotary table 5 and the polishing pad 2 are rotated in the direction indicated by the arrow about the table shaft 5a by the table rotation motor 21. The polishing pad 2 is attached to the upper surface of the rotary table 5. The exposed surface of the polishing pad 2 constitutes a polishing surface 2a for polishing the wafer W.

[0022] The wafer W is polished as follows. The wafer W is held by the polishing head 7 with its polished surface facing downward. While rotating the polishing head 7 and the rotary table 5 respectively, polishing liquid (for example, slurry containing abrasive grains) is supplied from a polishing liquid supply nozzle 10 provided above the rotary table 5 onto the polishing surface 2a of the polishing pad 2. The polishing pad 2 rotates integrally with the rotary table 5 about its central axis. The polishing head 7 is moved to a predetermined height by a polishing head elevating mechanism (not shown). Further, while maintaining the polishing head 7 at the above-mentioned predetermined height, the wafer W is pressed against the polishing surface 2a of the polishing pad 2. The wafer W rotates integrally with the polishing head 7. With the polishing liquid present on the polishing surface 2a of the polishing pad 2, the wafer W is brought into sliding contact with the polishing surface 2a. The surface of the wafer W is polished by a combination of the chemical action of the polishing liquid and the mechanical action of the abrasive grains contained in the polishing liquid and / or the polishing pad 2.

[0023] The polishing apparatus includes a dresser 50 for dressing the polishing surface 2a of the polishing pad 2. This dresser 50 includes a dressing disk 51 that is brought into sliding contact with the polishing surface 2a of the polishing pad 2, a dresser shaft 52 to which the dressing disk 51 is connected, and a dresser swing arm 55 that rotatably supports the dresser shaft 52. The lower surface of the dressing disk 51 constitutes a dressing surface 51a, and this dressing surface 51a is composed of abrasive grains (for example, diamond particles).

[0024] The dresser shaft 52 is connected to a disk pressing mechanism (including, for example, an air cylinder) (not shown) disposed within the dresser swing arm 55. This disk pressing mechanism is configured to press the dressing surface 51a of the dressing disk 51 against the polishing surface 2a of the polishing pad 2 via the dresser shaft 52. Further, the dresser shaft 52 is connected to a disk rotation mechanism (including, for example, an electric motor) (not shown) disposed within the dresser swing arm 55. This disk rotation mechanism is configured to rotate the dressing disk 51 in the direction indicated by the arrow via the dresser shaft 52.

[0025] Dressing of the polishing surface 2a of the polishing pad 2 is performed as follows. The polishing pad 2 is rotated by the table rotation motor 21 together with the rotary table 5. The dressing disk 51 is rotated by a disk rotation mechanism (not shown) about the dresser shaft 52, and the dressing surface 51a of the dressing disk 51 is pressed against the polishing surface 2a by a disk pressing mechanism (not shown) and brought into sliding contact with the polishing surface 2a. During rotation of the dressing disk 51, the dresser swing arm 55 is pivoted about the support shaft 58 to swing the dressing disk 51 in the radial direction of the polishing surface 2a. In this way, the polishing pad 2 is slightly scraped off by the dressing disk 51, and the polishing surface 2a is dressed (regenerated). Dressing of the polishing surface 2a of the polishing pad 2 is performed during polishing of the wafer W or after polishing of the wafer W.

[0026] A plurality of two-fluid nozzles 8 are disposed above the polishing pad 2 and arranged along the radial direction of the polishing pad 2. Each two-fluid nozzle 8 is configured to form a two-fluid jet flow composed of a mixed fluid of a liquid and a gas and discharge the two-fluid jet flow toward the polishing surface 2a of the polishing pad 2. The plurality of two-fluid nozzles 8 and the plurality of pad cleaning nozzles 9 are held by the nozzle carrier 22. The nozzle carrier 22 is fixed to the support column 32.

[0027] The plurality of pad cleaning nozzles 9 are arranged along the radial direction of the polishing pad 2, and are configured to discharge a jet of liquid discharge fluid toward the polishing surface 2a of the polishing pad 2. The plurality of pad cleaning nozzles 9 are arranged downstream of the plurality of two-fluid nozzles 8 in the rotational direction of the polishing pad 2.

[0028] The plurality of two-fluid nozzles 8 and pad cleaning nozzles 9 simultaneously discharge the two-fluid jet and the liquid discharge fluid jet toward the polishing surface 2a of the polishing pad 2 to clean the polishing surface 2a. The cleaning of the polishing surface 2a of the polishing pad 2 is performed after the wafer W has been polished and before the next wafer is polished. The cleaning of the polishing pad 2 using the two-fluid nozzles 8 and the pad cleaning nozzles 9 (hereinafter sometimes referred to as the pad cleaning operation) may be performed before or after the dressing of the polishing pad 2 using a dresser (hereinafter sometimes referred to as the dressing operation), or may be performed during the dressing operation.

[0029] For example, after the polishing of the wafer W, the dressing operation may be performed, and then the pad cleaning operation may be performed. In another example, after the polishing of the wafer W, the dressing operation and the pad cleaning operation may be performed simultaneously. In still another example, while polishing the wafer W, the dressing operation may be performed, and after the polishing and dressing operations of the wafer W, the pad cleaning operation may be performed. The time of the pad cleaning operation, that is, the cleaning time of the polishing pad 2 using the two-fluid nozzles 8 and the pad cleaning nozzles 9 can be arbitrarily set.

[0030] The polishing apparatus includes an operation control unit 30 that controls the operations of the polishing apparatus, including the polishing operation, dressing operation, and pad cleaning operation of the wafer W. The operation control unit 30 is composed of at least one computer. The operation control unit 30 includes a storage device 30a in which a program is stored, and a processing device 30b that executes calculations according to the instructions included in the program. The storage device 30a includes a main storage device such as a random access memory (RAM), and auxiliary storage devices such as a hard disk drive (HDD) and a solid state drive (SSD). Examples of the processing device 30b include a CPU (central processing unit) and a GPU (graphics processing unit). However, the specific configuration of the operation control unit 30 is not limited to these examples.

[0031] In the embodiment shown in FIG. 1, the non-contact pad cleaning device that cleans the polishing surface 2a of the polishing pad 2 without contact includes a plurality of two-fluid nozzles 8, a pad cleaning nozzle 9, and a rotating table 5. When the flow rate of the liquid contained in the two-fluid jet discharged from the two-fluid nozzle 8 is sufficiently high, the pad cleaning nozzle 9 may not be provided. The rotating table 5 forms a part of the non-contact pad cleaning device and also forms a part of the polishing apparatus shown in FIG. 1.

[0032] FIG. 2 is a top view of an embodiment of a plurality of two-fluid nozzles 8, a pad cleaning nozzle 9, and a polishing pad 2 as seen from above. In the embodiment shown in FIG. 2, the polishing pad 2 rotates in the direction indicated by the arrow (counterclockwise in the example of FIG. 2). The plurality of two-fluid nozzles 8 are fixed to the nozzle carrier 22 by the nozzle holding portion 35. The pad cleaning nozzles 9 are arranged along the radial direction of the polishing pad 2. These pad cleaning nozzles 9 are arranged facing the outer side in the radial direction of the polishing pad 2, and form a flow of liquid discharge fluid toward the outer side in the radial direction on the polishing surface 2a of the polishing pad 2.

[0033] In the embodiment shown in FIG. 2, four two-fluid nozzles 8 are arranged in the radial direction of the polishing pad 2. However, the number of the two-fluid nozzles 8 is not limited to this embodiment, and two, three, or five or more two-fluid nozzles 8 may be provided.

[0034] In this embodiment, the positions of the plurality of two-fluid nozzles 8 and the pad cleaning nozzle 9 are fixed and are always located above the polishing pad 2. In one embodiment, the plurality of two-fluid nozzles 8 may be arranged away from the pad cleaning nozzle 9. For example, the plurality of two-fluid nozzles 8 may be held by a nozzle holding portion or a nozzle carrier (not shown) away from the pad cleaning nozzle 9. Even in this case, the pad cleaning nozzle 9 is arranged downstream of the two-fluid nozzles 8 in the rotational direction of the polishing pad 2. Each two-fluid nozzle 8 is a fan nozzle configured to form a fan-shaped two-fluid jet. Each two-fluid nozzle 8 has a jet outlet 8a at its bottom for discharging the two-fluid jet.

[0035] As shown in FIG. 2, when viewed from a direction perpendicular to the polishing surface 2a of the polishing pad 2, the jet outlets 8a of the plurality of two-fluid nozzles 8 are inclined obliquely with respect to a reference line RL extending in the radial direction of the polishing pad 2. The reference line RL is an imaginary straight line passing through the center Cr of the polishing pad 2 and extending in the radial direction of the polishing pad 2. In this embodiment, when viewed from a direction perpendicular to the polishing surface 2a of the polishing pad 2, the jet outlets 8a of the plurality of two-fluid nozzles 8 are on the reference line RL.

[0036] Figure 3 is an enlarged view of the two-fluid nozzle 8. The ejection port 8a of each two-fluid nozzle 8 is inclined at a predetermined angle α with respect to the reference line RL. More specifically, the ejection port 8a of each two-fluid nozzle 8 is inclined in the same direction as the rotation direction of the polishing pad 2. In the embodiment shown in FIG. 3, since the polishing pad 2 rotates counterclockwise, the ejection port 8a of each two-fluid nozzle 8 is also inclined counterclockwise with respect to the reference line RL when viewed from above. The ejection ports 8a of the four two-fluid nozzles 8 are inclined at the same angle, but they may be inclined at different angles. For example, the inclination angle α of the ejection ports 8a of the four two-fluid nozzles 8 with respect to the reference line RL may increase according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8.

[0037] As shown in FIG. 2, the ejection ports 8a of the plurality of two-fluid nozzles 8 are arranged at equal intervals from the center Cr to the outer periphery of the polishing pad 2. Therefore, when the polishing pad 2 is rotating, the two-fluid nozzles 8 can guide the two-fluid jet flow to the entire polishing surface 2a of the polishing pad 2.

[0038] FIG. 4 is a diagram showing an embodiment of the two-fluid nozzle 8 when discharging the two-fluid jet flow, and FIG. 5 is a diagram for explaining the flow of the liquid contained in the two-fluid jet flow discharged from the two-fluid nozzle 8. The fan-shaped two-fluid jet flows discharged from the plurality of two-fluid nozzles 8 collide with the polishing surface 2a of the polishing pad 2 without hitting each other. The elliptical dotted line shown in FIG. 5 represents the region (hereinafter referred to as the collision region) where the two-fluid jet flow collides with the polishing surface 2a. These collision regions are inclined obliquely with respect to the reference line RL and are arranged on the reference line RL.

[0039] The two-fluid jet can remove foreign matters (e.g., abrasive grains of slurry, abrasive debris such as reaction by-products generated during wafer polishing, debris of the polishing pad 2 generated during the dressing operation, etc.) from minute holes formed on the polishing surface 2a of the polishing pad 2. The liquid contained in the two-fluid jet forms a liquid flow on the polishing surface 2a after the two-fluid jet collides with the polishing surface 2a of the polishing pad 2. As shown in FIG. 5, since the polishing pad 2 is rotating in the direction indicated by the arrow, due to the centrifugal force and the friction between the polishing pad 2 and the liquid, the liquid flows toward the outside of the polishing pad 2 and in the rotation direction of the polishing pad 2. Such a liquid flow can wash away the foreign matters discharged from the holes of the polishing pad 2 from the polishing pad 2. Further, the flow of the liquid discharge fluid indicated by the thick white arrow can enhance the action of discharging the liquid contained in the two-fluid jet and the foreign matters contained in the liquid from the polishing pad 2.

[0040] FIG. 6 is a view showing another embodiment of the arrangement of the two-fluid nozzles 8. As shown in FIG. 6, each two-fluid nozzle 8 may be inclined with respect to the polishing surface 2a so that the two-fluid jet is discharged to the radially outer side of the polishing pad 2. Each two-fluid nozzle 8 is inclined so that the jet outlet 8a of each two-fluid nozzle 8 faces the radially outer side of the polishing pad 2. Since the two-fluid nozzle 8 can form a liquid flow flowing radially outward, it becomes easier to discharge foreign matters from the polishing pad 2.

[0041] FIG. 7 is a view for explaining the inclination angle of the two-fluid nozzle 8 with respect to the polishing surface 2a. The inclination angle θ of each two-fluid nozzle 8 with respect to the direction perpendicular to the polishing surface 2a is greater than 0 degree and equal to or less than 60 degrees. More preferably, the inclination angle θ of each two-fluid nozzle 8 is within the range of 15 to 30 degrees. The plurality of two-fluid nozzles 8 may be inclined with respect to the polishing surface 2a at different angles. In one embodiment, each two-fluid nozzle 8 is inclined with respect to the polishing surface 2a such that the jet outlet 8a of each two-fluid nozzle 8 faces the radially outer side of the polishing pad 2 and faces the downstream side in the rotation direction of the polishing pad 2. Since the two-fluid nozzle 8 can form a liquid flow flowing radially outward, it becomes easier to discharge foreign matters from the polishing pad 2.

[0042] FIG. 8 is a view showing still another embodiment of the arrangement of the two-fluid nozzles 8. In FIG. 8, illustration of the pad cleaning nozzle 9, the nozzle carrier 22, and the nozzle holder 35 is omitted. When viewed from a direction perpendicular to the polishing surface 2a of the polishing pad 2, the inclination angle of the ejection ports 8a of the plurality of two-fluid nozzles 8 with respect to the reference line RL increases according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8. The inclination angle of the ejection port 8a of each two-fluid nozzle 8 with respect to the reference line RL corresponds to the angle α described with reference to FIG. 3.

[0043] In addition, when viewed from a direction perpendicular to the polishing surface 2a of the polishing pad 2, the distance L from the reference line RL of the ejection ports 8a of the plurality of two-fluid nozzles 8 increases according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8. The distance L from the reference line RL of the ejection port 8a of each two-fluid nozzle 8 is the distance toward the downstream side from the reference line RL in the rotation direction of the polishing pad 2.

[0044] Although not shown, the plurality of two-fluid nozzles 8 may be fixed to the nozzle carrier 22 by the nozzle holder 35 (see FIG. 2), or the pad cleaning nozzle 9 may be arranged away from the plurality of two-fluid nozzles 8.

[0045] FIG. 9 is a perspective view of the two-fluid nozzle 8 shown in FIG. 8, and FIG. 10 is a view for explaining the flow of the liquid contained in the two-fluid jet discharged from the two-fluid nozzle 8. The fan-shaped two-fluid jets discharged from the plurality of two-fluid nozzles 8 collide with the polishing surface 2a of the polishing pad 2. The elliptical dotted line shown in FIG. 10 represents the collision region where the two-fluid jet collides with the polishing surface 2a. These collision regions are inclined obliquely with respect to the reference line RL and are connected in an arc from the center Cr to the outer periphery of the polishing pad 2.

[0046] The liquid that constitutes the two-fluid jet discharged from each two-fluid nozzle 8 merges with the liquid that constitutes the two-fluid jet discharged from other two-fluid nozzles 8, forming a strong flow of liquid from the center Cr to the outer periphery of the polishing pad 2. This flow of liquid can wash away foreign matter discharged from the holes of the polishing pad 2 from the polishing pad 2. Furthermore, the flow of the liquid discharge fluid indicated by the thick white arrow can enhance the action of discharging the liquid contained in the two-fluid jet and the foreign matter contained in the liquid from the polishing pad 2.

[0047] In one embodiment, as shown in FIG. 11, each two-fluid nozzle 8 is inclined with respect to the polishing surface 2a such that a two-fluid jet is discharged to the radially outer side of the polishing pad 2. The plurality of two-fluid nozzles 8 may be inclined with respect to the polishing surface 2a at different angles. Each two-fluid nozzle 8 is inclined such that the nozzle outlet 8a of each two-fluid nozzle 8 faces the radially outer side of the polishing pad 2. The inclination angle of each two-fluid nozzle 8 with respect to the direction perpendicular to the polishing surface 2a is greater than 0 degrees and 60 degrees or less, and more preferably, the inclination angle of each two-fluid nozzle 8 is within the range of 15 to 30 degrees. In one embodiment, each two-fluid nozzle 8 is inclined with respect to the polishing surface 2a such that the nozzle outlet 8a of each two-fluid nozzle 8 faces the radially outer side of the polishing pad 2 and faces the downstream side in the rotational direction of the polishing pad 2. Since the two-fluid nozzle 8 can form a flow of liquid flowing radially outward, it becomes easier to discharge foreign matter from the polishing pad 2.

[0048] Examples of the liquid supplied to the two-fluid nozzle 8 and the liquid discharge fluid supplied to the pad cleaning nozzle 9 include pure water and pure water containing fine bubbles. Examples of the gas supplied to the two-fluid nozzle 8 include air and an inert gas (for example, nitrogen gas).

[0049] FIG. 12 is a schematic diagram showing an embodiment of a configuration for supplying liquid and gas to the two-fluid nozzle 8. The non-contact pad cleaning device includes a liquid supply line 61 and a gas supply line 65 connected to a plurality of two-fluid nozzles 8. The liquid supply line 61 is connected to a liquid supply source (for example, a pure water supply source) not shown, and the gas supply line 65 is connected to a gas supply source (for example, an air supply source or an inert gas supply source) not shown.

[0050] The liquid supply line 61 has a plurality of branched liquid lines 62, and the gas supply line 65 has a plurality of branched gas lines 66. The plurality of two-fluid nozzles 8 are respectively connected to the plurality of branched liquid lines 62, and further respectively connected to the plurality of branched gas lines 66.

[0051] The non-contact pad cleaning device includes a liquid flow control valve 71 disposed in the liquid supply line 61, a gas flow control valve 73 and a pressure regulator 75 disposed in the gas supply line 65. The liquid flow control valve 71 is configured to adjust the flow rate of the liquid supplied to the plurality of two-fluid nozzles 8. The gas flow control valve 73 is configured to adjust the flow rate of the gas supplied to the plurality of two-fluid nozzles 8. The pressure regulator 75 is configured to adjust the pressure of the gas supplied to the plurality of two-fluid nozzles 8. The liquid flow control valve 71, the gas flow control valve 73, and the pressure regulator 75 are electrically connected to the operation control unit 30, and the operations of the liquid flow control valve 71, the gas flow control valve 73, and the pressure regulator 75 are controlled by the operation control unit 30.

[0052] The liquid and gas are supplied to each two-fluid nozzle 8 through the liquid supply line 61 and the gas supply line 65 and are mixed inside each two-fluid nozzle 8. Then, the mixed fluid of the liquid and gas is discharged as a two-fluid jet from the jet outlet 8a of each two-fluid nozzle 8.

[0053] FIG. 13 is a schematic diagram showing another embodiment of the non-contact pad cleaning device. Since the configuration of this embodiment not particularly described is the same as that of the embodiment described with reference to FIG. 12, redundant description thereof will be omitted. As shown in FIG. 13, the non-contact pad cleaning device of this embodiment further includes a fine bubble generator 78 connected to the liquid supply line 61. A liquid such as pure water is first supplied to the fine bubble generator 78, and the fine bubble generator 78 generates a liquid containing fine bubbles (microbubbles). The configuration of the fine bubble generator 78 is not particularly limited, and a commercially available fine bubble generator can be used. The liquid containing fine bubbles is supplied to the two-fluid nozzle 8 through the liquid supply line 61. The two-fluid nozzle 8 discharges a two-fluid jet containing fine bubbles onto the polishing pad 2.

[0054] FIG. 14 is a schematic diagram for explaining an example of the action of fine bubbles. The fine bubbles 400 are usually negatively charged. Foreign matters 500 such as polishing debris are surrounded by the fine bubbles 400 present in the liquid, and on the other hand, the fine bubbles 400 adhere to the polishing surface 2a of the polishing pad 2. The fine bubbles 400 surrounding the foreign matter 500 and the fine bubbles 400 surrounding another foreign matter 500 repel each other due to the negative charge, so that the foreign matters 500 can be prevented from adhering to each other. Further, since the fine bubbles 400 are present on the polishing surface 2a, the fine bubbles 400 surrounding the foreign matter 500 repel the fine bubbles 400 on the polishing surface 2a, and the foreign matter 500 can be prevented from reattaching to the polishing surface 2a.

[0055] FIG. 15 is a schematic diagram for explaining another example of the action of fine bubbles. Tiny foreign matters 500 adhere to the fine bubbles 400, and the foreign matters 500 are discharged from the polishing pad 2 together with the fine bubbles 400 by the flow of the liquid.

[0056] In one embodiment, as shown in FIG. 16, the fine bubble generator 78 may be connected to a liquid discharge fluid line 80 that supplies liquid discharge fluid to the plurality of pad cleaning nozzles 9 instead of or in addition to the liquid supply line 61. The liquid discharge fluid line 80 is connected to the plurality of pad cleaning nozzles 9. The liquid discharge fluid containing fine bubbles is supplied to the pad cleaning nozzles 9 through the liquid discharge fluid line 80. The pad cleaning nozzles 9 discharge a jet of the liquid discharge fluid containing fine bubbles onto the polishing pad 2. Also in this embodiment, the effects of the fine bubbles described with reference to FIGS. 14 and 15 can be obtained.

[0057] FIG. 17 is a schematic diagram showing still another embodiment of the non-contact pad cleaning apparatus. Since the configuration of this embodiment not particularly described is the same as that of the embodiment described with reference to FIG. 13, the overlapping description thereof is omitted. As shown in FIG. 17, the non-contact pad cleaning apparatus of this embodiment further includes a liquid heating device 83 connected to the liquid supply line 61. The liquid heating device 83 is configured to heat the liquid flowing through the liquid supply line 61. Specifically, the liquid heating device 83 is configured to heat the liquid flowing through the liquid supply line 61 to a temperature within the range of 20°C to 100°C. The specific configuration of the liquid heating device 83 is not particularly limited, and for example, an electric heater or the like can be used for the liquid heating device 83.

[0058] The heated liquid is supplied to the two-fluid nozzle 8 through the liquid supply line 61. The two-fluid nozzle 8 discharges a two-fluid jet containing the heated liquid onto the polishing pad 2. The temperature of the polishing pad 2 rises due to the heated liquid, and the polishing pad 2 becomes softer. As a result, the two-fluid jet can more easily remove foreign matter from the holes of the polishing pad 2. The liquid heating device 83 is applicable to each of the embodiments described with reference to FIGS. 1 to 16.

[0059] FIG. 18 is a schematic diagram showing still another embodiment of the non-contact pad cleaning device. The configuration of this embodiment that is not particularly described is the same as that of the embodiment described with reference to FIG. 13, so the overlapping description thereof will be omitted. As shown in FIG. 18, the distance from the polishing surface 2a of the ejection port 8a of the two-fluid nozzle 8 located on the outer peripheral side of the polishing pad 2 is smaller than the distance from the polishing surface 2a of the ejection port 8a of the two-fluid nozzle 8 located on the central side of the polishing pad 2. This is for the following reason. That is, as the distance from the center Cr of the polishing pad 2 increases, the circumferential length on the polishing surface 2a of the polishing pad 2 becomes larger. Therefore, the two-fluid nozzle 8 located on the outer peripheral side of the polishing pad 2 requires a higher cleaning ability than the two-fluid nozzle 8 located on the central side of the polishing pad 2.

[0060] According to this embodiment, since the ejection port 8a of the two-fluid nozzle 8 located on the outer peripheral side of the polishing pad 2 is arranged closer to the polishing surface 2a, the cleaning effect of the outer peripheral region of the polishing surface 2a of the polishing pad 2 can be improved. In one embodiment, as shown in FIG. 18, the distance from the polishing surface 2a of the ejection ports 8a of the plurality of two-fluid nozzles 8 may be made smaller according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8. The two-fluid nozzles 8 arranged in this way can uniformly clean the entire polishing surface 2a of the polishing pad 2. The arrangement of the two-fluid nozzles 8 described with reference to FIG. 18 is applicable to each of the embodiments described with reference to FIGS. 1 to 17.

[0061] In another embodiment, as shown in FIG. 19, the distance from the polishing surface 2a of the ejection port 8a of the two-fluid nozzle 8 located on the outer peripheral side of the polishing pad 2 is larger than the distance from the polishing surface 2a of the ejection port 8a of the two-fluid nozzle 8 located on the central side of the polishing pad 2. This is for the following reason. That is, the outer peripheral side of the polishing surface 2a of the polishing pad 2 has a larger area to be cleaned than the central side. Since the ejection port 8a of the two-fluid nozzle 8 located on the outer peripheral side of the polishing pad 2 is far from the polishing surface 2a, the two-fluid jet spreads along its traveling direction and can clean a wider area.

[0062] In one embodiment, as shown in FIG. 19, the distance from the polished surface 2a of the ejection port 8a of the plurality of two-fluid nozzles 8 may be increased according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8. The arrangement of the two-fluid nozzles 8 described with reference to FIG. 19 is applicable to each of the embodiments described with reference to FIGS. 1 to 17.

[0063] FIG. 20 is a schematic diagram showing still another embodiment of the non-contact pad cleaning device. Since the configuration of this embodiment not particularly described is the same as that of the embodiment described with reference to FIG. 13, the overlapping description thereof is omitted. As shown in FIG. 20, the non-contact pad cleaning device further includes a plurality of ultrasonic generators 87 respectively attached to the plurality of two-fluid nozzles 8. These ultrasonic generators 87 are electrically connected to the operation control unit 30, and the operation of the ultrasonic generators 87 is controlled by the operation control unit 30.

[0064] The plurality of ultrasonic generators 87 are configured to apply ultrasonic waves to the two-fluid jets discharged from the plurality of two-fluid nozzles 8. The frequency of the ultrasonic waves is selected from the range of 100 kHz to 3.0 MHz. The operation control unit 30 gives commands to each ultrasonic generator 87 to generate ultrasonic waves of a preselected frequency. The plurality of ultrasonic generators 87 may generate ultrasonic waves of the same frequency or may generate different frequencies.

[0065] In one embodiment, the operation control unit 30 controls the operation of the plurality of ultrasonic generators 87 such that the frequency of the ultrasonic waves applied to the two-fluid jets discharged from the two-fluid nozzles 8 arranged on the outer peripheral side of the polishing pad 2 is lower than the frequency of the ultrasonic waves applied to the two-fluid jets discharged from the two-fluid nozzles 8 arranged on the central side of the polishing pad 2. Generally, when the frequency of the ultrasonic waves applied to the two-fluid jet is lowered, the cleaning ability of the two-fluid jet is improved. According to this embodiment, the cleaning effect of the outer peripheral region of the polished surface 2a of the polishing pad 2 can be improved.

[0066] In one embodiment, the operation control unit 30 controls the operations of the plurality of ultrasonic generators 87 such that the frequency of the ultrasonic waves applied to the two-fluid jets discharged from the plurality of two-fluid nozzles 8 decreases according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8. The two-fluid nozzle 8 incorporating the ultrasonic generator 87 controlled in this manner can uniformly clean the entire polishing surface 2a of the polishing pad 2.

[0067] FIG. 21 is a schematic diagram showing still another embodiment of the non-contact pad cleaning device. Since the configuration of this embodiment which will not be particularly described is the same as that of the embodiment described with reference to FIG. 15, the overlapping description thereof will be omitted. The non-contact pad cleaning device includes a plurality of liquid flow control valves 71 respectively connected to a plurality of branch liquid lines 62, a plurality of gas flow control valves 73 respectively connected to a plurality of branch gas lines 66, and a plurality of pressure regulators 75 respectively connected to the plurality of branch gas lines 66.

[0068] The plurality of liquid flow control valves 71 are respectively connected to the plurality of two-fluid nozzles 8 via a liquid supply line 61. The plurality of gas flow control valves 73 are respectively connected to the plurality of two-fluid nozzles 8 via a gas supply line 65. The plurality of pressure regulators 75 are also respectively connected to the plurality of two-fluid nozzles 8 via the gas supply line 65.

[0069] The plurality of liquid flow control valves 71 can independently adjust the flow rate of the liquid supplied to the plurality of two-fluid nozzles 8. The plurality of gas flow control valves 73 can independently adjust the flow rate of the gas supplied to the plurality of two-fluid nozzles 8. The plurality of pressure regulators 75 can independently adjust the pressure of the gas supplied to the plurality of two-fluid nozzles 8. The plurality of liquid flow control valves 71, the plurality of gas flow control valves 73, and the plurality of pressure regulators 75 are electrically connected to the operation control unit 30, and the operations of the plurality of liquid flow control valves 71, the plurality of gas flow control valves 73, and the plurality of pressure regulators 75 are controlled by the operation control unit 30. The fine bubble generator 78 is disposed upstream of the plurality of liquid flow control valves 71.

[0070] In one embodiment, the operation control unit 30 controls the operations of the plurality of liquid flow control valves 71 such that the flow rate of the liquid supplied to the two-fluid nozzle 8 disposed on the outer peripheral side of the polishing pad 2 is higher than the flow rate of the liquid supplied to the two-fluid nozzle 8 disposed on the central side of the polishing pad 2. The two-fluid nozzle 8 disposed on the outer peripheral side of the polishing pad 2 can apply a stronger two-fluid jet to the outer peripheral surface of the polishing surface 2a of the polishing pad 2 than the two-fluid nozzle 8 disposed on the central side of the polishing pad 2. According to the present embodiment, the cleaning effect of the outer peripheral region of the polishing surface 2a of the polishing pad 2 can be improved.

[0071] In one embodiment, the operation control unit 30 controls the operations of the plurality of liquid flow control valves 71 such that the flow rate of the liquid supplied to the plurality of two-fluid nozzles 8 increases according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8. By controlling the flow rate of the liquid in this way, the two-fluid nozzle 8 can uniformly clean the entire polishing surface 2a of the polishing pad 2.

[0072] In another embodiment, the operation control unit 30 controls the operations of the plurality of liquid flow control valves 71 such that the flow rate of the liquid supplied to the two-fluid nozzle 8 disposed on the central side of the polishing pad 2 is higher than the flow rate of the liquid supplied to the two-fluid nozzle 8 disposed on the outer peripheral side of the polishing pad 2. The slurry adhering to the central portion of the polishing pad 2 has a longer distance to move to the outside of the polishing pad 2 compared to the slurry adhering to the outer peripheral portion of the polishing pad 2. Therefore, in this embodiment, in order to improve the liquid dischargeability at the central portion of the polishing pad 2, the flow rate of the liquid of the two-fluid nozzle 8 on the central side is made higher than the flow rate of the liquid of the two-fluid nozzle 8 on the outer peripheral side.

[0073] In one embodiment, the operation control unit 30 controls the operations of the plurality of liquid flow control valves 71 such that the flow rate of the liquid supplied to the plurality of two-fluid nozzles 8 decreases according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8.

[0074] In one embodiment, the operation control unit 30 controls the operations of the plurality of gas flow control valves 73 such that the flow rate of the gas supplied to the two-fluid nozzle 8 disposed on the outer peripheral side of the polishing pad 2 is higher than the flow rate of the gas supplied to the two-fluid nozzle 8 disposed on the central side of the polishing pad 2. The two-fluid nozzle 8 disposed on the outer peripheral side of the polishing pad 2 can apply a stronger two-fluid jet to the outer peripheral surface of the polishing surface 2a of the polishing pad 2 than the two-fluid nozzle 8 disposed on the central side of the polishing pad 2. According to the present embodiment, the cleaning effect of the outer peripheral region of the polishing surface 2a of the polishing pad 2 can be improved.

[0075] In one embodiment, the operation control unit 30 controls the operations of the plurality of gas flow control valves 73 such that the flow rate of the gas supplied to the plurality of two-fluid nozzles 8 increases according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8. By controlling the gas flow rate in this way, the two-fluid nozzle 8 can uniformly clean the entire polishing surface 2a of the polishing pad 2.

[0076] In another embodiment, the operation control unit 30 controls the operations of the plurality of gas flow control valves 73 such that the flow rate of the gas supplied to the two-fluid nozzle 8 disposed on the central side of the polishing pad 2 is higher than the flow rate of the gas supplied to the two-fluid nozzle 8 disposed on the outer peripheral side of the polishing pad 2. The slurry adhering to the central portion of the polishing pad 2 has a longer distance to move to the outside of the polishing pad 2 compared to the slurry adhering to the outer peripheral portion of the polishing pad 2. Therefore, in this embodiment, in order to improve the liquid dischargeability at the central portion of the polishing pad 2, the gas flow rate of the two-fluid nozzle 8 on the central side is made higher than the gas flow rate of the two-fluid nozzle 8 on the outer peripheral side.

[0077] In one embodiment, the operation control unit 30 controls the operations of the plurality of gas flow control valves 73 such that the flow rate of the gas supplied to the plurality of two-fluid nozzles 8 decreases according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8.

[0078] In one embodiment, the operation control unit 30 controls the operations of the plurality of pressure regulators 75 such that the pressure of the gas supplied to the two-fluid nozzle 8 disposed on the outer peripheral side of the polishing pad 2 is higher than the pressure of the gas supplied to the two-fluid nozzle 8 disposed on the central side of the polishing pad 2. The two-fluid nozzle 8 disposed on the outer peripheral side of the polishing pad 2 can apply a stronger two-fluid jet to the outer peripheral surface of the polishing surface 2a of the polishing pad 2 than the two-fluid nozzle 8 disposed on the central side of the polishing pad 2. According to the present embodiment, the cleaning effect of the outer peripheral region of the polishing surface 2a of the polishing pad 2 can be improved.

[0079] In one embodiment, the operation control unit 30 controls the operations of the plurality of pressure regulators 75 such that the pressure of the gas supplied to the plurality of two-fluid nozzles 8 increases according to the distance from the center Cr of the polishing pad 2 of each two-fluid nozzle 8. By controlling the gas pressure in this way, the two-fluid nozzle 8 can uniformly clean the entire polishing surface 2a of the polishing pad 2.

[0080] The arrangements of the plurality of liquid flow rate control valves 71, the plurality of gas flow rate control valves 73, and the plurality of pressure regulators 75 described with reference to FIG. 21 are applicable to each of the embodiments described with reference to FIGS. 1 to 20.

[0081] FIG. 22 is a schematic diagram showing still another embodiment of the non-contact pad cleaning device, and FIG. 23 is a top view of the two-fluid liquid nozzle 8 and the pad cleaning nozzle 9 shown in FIG. 22. The configuration of this embodiment not particularly described is the same as that of the embodiment described with reference to FIG. 1, and thus the overlapping description is omitted. The non-contact pad cleaning device includes a nozzle swing mechanism 90 that swings a plurality of two-fluid nozzles 8 along the polishing surface 2a. The plurality of two-fluid nozzles 8 are held by a nozzle holding portion 35. The plurality of two-fluid nozzles 8 are connected to a liquid supply line 61 and a gas supply line 65. The pad cleaning nozzle 9 is disposed downstream of the two-fluid nozzle 8 in the rotation direction of the polishing pad 2.

[0082] The nozzle swing mechanism 90 is configured to swing the plurality of two-fluid nozzles 8 in the radial direction of the polishing pad 2 by swinging the nozzle holding portion 35. The nozzle swing mechanism 90 is configured to be able to change the swing speed of the plurality of two-fluid nozzles 8. In one embodiment, the nozzle swing mechanism 90 is configured to swing the plurality of two-fluid nozzles 8 in the radial direction of the polishing pad 2 by alternately rotating the nozzle holding portion 35 clockwise and counterclockwise by a predetermined angle about its end. In another embodiment, the nozzle swing mechanism 90 may be configured to swing the plurality of two-fluid nozzles 8 in the radial direction of the polishing pad 2 by translating the nozzle holding portion 35.

[0083] FIG. 24 is a view of the two-fluid nozzle 8 as seen from the direction indicated by the arrow A in FIG. 22. The ejection port 8a of each two-fluid nozzle 8 faces outward in the radial direction of the polishing pad 2. The inclination angle θ of each two-fluid nozzle 8 with respect to the direction perpendicular to the polishing surface 2a is greater than 0 degrees and equal to or less than 60 degrees. More preferably, the inclination angle θ of each two-fluid nozzle 8 is in the range of 15 to 30 degrees. The plurality of two-fluid nozzles 8 may be inclined with respect to the polishing surface 2a at different angles.

[0084] Since the ejection ports 8a of the plurality of two-fluid nozzles 8 face outward in the radial direction of the polishing pad 2, the two-fluid jets ejected from the plurality of ejection ports 8a form a flow of liquid that moves outward on the polishing surface 2a. This outward flow of liquid is accelerated by the centrifugal force generated by the rotating polishing pad 2, and foreign substances such as polishing debris can be washed away from the polishing pad 2.

[0085] The arrangement of the two-fluid nozzles 8 is not limited to the embodiment described with reference to FIGS. 22 to 24. In one embodiment, the plurality of two-fluid nozzles 8 may be arranged linearly. In the embodiment described with reference to FIGS. 22 to 24, five two-fluid nozzles 8 are provided, but the number of two-fluid nozzles 8 is not limited to the above embodiment. In one embodiment, a single two-fluid nozzle 8 may be provided.

[0086] The embodiments described with reference to FIGS. 1 to 24 may be combined as appropriate. The configurations of the embodiments described with reference to FIGS. 1 to 21, for example, the fine bubble generator 78, the ultrasonic generator 87, the liquid heating device 83, the inclination of the two-fluid nozzle 8 with respect to the polishing surface 2a, etc., may be applied to the embodiments described with reference to FIGS. 22 to 24.

[0087] The above-described embodiments are described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention pertains to practice the present invention. Various modifications of the above embodiments can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is interpreted in the broadest scope in accordance with the technical idea defined by the claims.

Explanation of Reference Numerals

[0088] 2 Polishing pad 2a Polishing surface 5 Rotating table 5a Table axis 7 Polishing head 8 Two-fluid nozzle 8a Nozzle outlet 9 Pad cleaning nozzle 10 Polishing liquid supply nozzle 14 Support shaft 16 Polishing head swing arm 18 Polishing head shaft 21 Table rotation motor 22 Nozzle carrier 30 Operation control unit 32 Support column 35 Nozzle holding part 50 Dressing tool 51 Dressing disk 51a Dressing surface 52 Dressing tool shaft 55 Dressing tool swing arm 58 Support shaft 61 Liquid supply line 62 Branch liquid line 65 Gas supply line 66 Branch gas line 71 Liquid flow control valve 73 Gas flow control valve 75 Pressure regulator 78 Fine bubble generator 80 Liquid discharge fluid line 83 Liquid heating device 87 Ultrasonic generator 90 Nozzle oscillation mechanism

Claims

1. A non-contact pad cleaning device for cleaning a polishing surface of a polishing pad for polishing a workpiece in a non-contact manner, comprising: a rotating table for rotating the polishing pad; a plurality of two-fluid nozzles disposed above the polishing pad; a liquid supply line and a gas supply line connected to the plurality of two-fluid nozzles; the plurality of two-fluid nozzles are arranged along the radial direction of the polishing pad; a non-contact pad cleaning device, wherein when viewed from a direction perpendicular to the polishing surface of the polishing pad, the ejection ports of the plurality of two-fluid nozzles are inclined obliquely with respect to a reference line extending in the radial direction of the polishing pad.

2. The non-contact pad cleaning device according to claim 1, wherein when viewed from a direction perpendicular to the polishing surface of the polishing pad, the ejection ports of the plurality of two-fluid nozzles are inclined in the same direction as the rotation direction of the polishing pad.

3. The non-contact pad cleaning device according to claim 1, wherein when viewed from a direction perpendicular to the polishing surface of the polishing pad, the ejection ports of the plurality of two-fluid nozzles are on the reference line.

4. The non-contact pad cleaning device according to claim 1, wherein when viewed from a direction perpendicular to the polishing surface of the polishing pad, the inclination angle of the ejection ports of the plurality of two-fluid nozzles with respect to the reference line increases according to the distance of each two-fluid nozzle from the center of the polishing pad.

5. When viewed from a direction perpendicular to the polishing surface of the polishing pad, the distance of the ejection ports of the plurality of two-fluid nozzles from the reference line increases according to the distance of each two-fluid nozzle from the center of the polishing pad, The non-contact pad cleaning device according to claim 4, wherein the distance of the ejection ports of each two-fluid nozzle from the reference line is a distance downstream from the reference line in the rotation direction of the polishing pad.

6. The non-contact pad cleaning device according to claim 1, further comprising a fine bubble generator connected to the liquid supply line.

7. The non-contact pad cleaning device according to claim 1, further comprising a liquid heating device connected to the liquid supply line for heating the liquid flowing through the liquid supply line.

8. The non-contact pad cleaning device according to claim 1, further comprising a pad cleaning nozzle for forming a jet of liquid discharge fluid for guiding the liquid contained in the two-fluid on the polishing surface of the polishing pad to the outer periphery of the polishing pad.

9. A liquid discharge fluid line for supplying a liquid discharge fluid to the pad cleaning nozzle; The non-contact pad cleaning device according to claim 8, further comprising a fine bubble generator connected to the liquid discharge fluid line.

10. The non-contact pad cleaning device according to claim 8, wherein the pad cleaning nozzle is disposed downstream of the plurality of two-fluid nozzles in the rotational direction of the polishing pad.

11. The plurality of two-fluid nozzles include a center-side two-fluid nozzle located on the center side of the polishing pad and an outer-periphery-side two-fluid nozzle located on the outer periphery side of the polishing pad. The non-contact pad cleaning device according to claim 1, wherein a distance from the polishing surface to the ejection port of the outer-periphery-side two-fluid nozzle is smaller than a distance from the polishing surface to the ejection port of the center-side two-fluid nozzle.

12. The plurality of two-fluid nozzles include a center-side two-fluid nozzle located on the center side of the polishing pad and an outer-periphery-side two-fluid nozzle located on the outer periphery side of the polishing pad. The non-contact pad cleaning device according to claim 1, wherein a distance from the polishing surface to the ejection port of the outer-periphery-side two-fluid nozzle is larger than a distance from the polishing surface to the ejection port of the center-side two-fluid nozzle.

13. The liquid supply line has a plurality of branched liquid lines respectively connected to the plurality of two-fluid nozzles. The non-contact pad cleaning device further includes a plurality of liquid flow control valves respectively connected to the plurality of branched liquid lines and an operation control unit for independently controlling the operations of the plurality of liquid flow control valves. The plurality of two-fluid nozzles include a center-side two-fluid nozzle located on the center side of the polishing pad and an outer-periphery-side two-fluid nozzle located on the outer periphery side of the polishing pad. The non-contact pad cleaning device according to claim 1, wherein the operation control unit is configured to control the operations of the plurality of liquid flow control valves such that a flow rate of the liquid supplied to the outer-periphery-side two-fluid nozzle is higher than a flow rate of the liquid supplied to the center-side two-fluid nozzle.

14. The liquid supply line has a plurality of branched liquid lines respectively connected to the plurality of two-fluid nozzles. The non-contact pad cleaning device further includes a plurality of liquid flow control valves respectively connected to the plurality of branched liquid lines and an operation control unit for independently controlling the operations of the plurality of liquid flow control valves. The plurality of two-fluid nozzles include a center-side two-fluid nozzle located on the center side of the polishing pad and an outer-periphery-side two-fluid nozzle located on the outer periphery side of the polishing pad. The operation control unit is configured to control the operations of the plurality of liquid flow rate control valves such that the flow rate of the liquid supplied to the center-side two-fluid nozzle is higher than the flow rate of the liquid supplied to the outer-periphery-side two-fluid nozzle. The non-contact pad cleaning device according to claim 1.

15. The gas supply line has a plurality of branched gas lines respectively connected to the plurality of two-fluid nozzles. The non-contact pad cleaning device further includes a plurality of gas flow rate control valves respectively connected to the plurality of branched gas lines, and an operation control unit that independently controls the operations of the plurality of gas flow rate control valves. The plurality of two-fluid nozzles include a center-side two-fluid nozzle located on the center side of the polishing pad and an outer-periphery-side two-fluid nozzle located on the outer periphery side of the polishing pad. The operation control unit is configured to control the operations of the plurality of gas flow rate control valves such that the flow rate of the gas supplied to the outer-periphery-side two-fluid nozzle is higher than the flow rate of the gas supplied to the center-side two-fluid nozzle. The non-contact pad cleaning device according to claim 1.

16. The gas supply line has a plurality of branched gas lines respectively connected to the plurality of two-fluid nozzles. The non-contact pad cleaning device further includes a plurality of gas flow rate control valves respectively connected to the plurality of branched gas lines, and an operation control unit that independently controls the operations of the plurality of gas flow rate control valves. The plurality of two-fluid nozzles include a center-side two-fluid nozzle located on the center side of the polishing pad and an outer-periphery-side two-fluid nozzle located on the outer periphery side of the polishing pad. The operation control unit is configured to control the operations of the plurality of gas flow rate control valves such that the flow rate of the gas supplied to the center-side two-fluid nozzle is higher than the flow rate of the gas supplied to the outer-periphery-side two-fluid nozzle. The non-contact pad cleaning device according to claim 1.

17. The gas supply line has a plurality of branched gas lines respectively connected to the plurality of two-fluid nozzles. The non-contact pad cleaning device further includes a plurality of pressure regulators respectively connected to the plurality of branched gas lines, and an operation control unit that independently controls the operations of the plurality of pressure regulators. The plurality of two-fluid nozzles include a central two-fluid nozzle located on the central side of the polishing pad and an outer peripheral two-fluid nozzle located on the outer peripheral side of the polishing pad. The operation control unit is configured to control the operations of the plurality of pressure regulators such that the pressure of the gas supplied to the outer peripheral two-fluid nozzle is higher than the pressure of the gas supplied to the central two-fluid nozzle. The non-contact pad cleaning device according to claim 1.

18. A non-contact pad cleaning device for non-contact cleaning of a polishing surface of a polishing pad for polishing a workpiece, a rotating table for rotating the polishing pad, two-fluid nozzles arranged above the polishing pad, a liquid supply line and a gas supply line connected to the two-fluid nozzles, a nozzle swing mechanism for swinging the two-fluid nozzles along the polishing surface, The ejection ports of the two-fluid nozzles face outward in the radial direction of the polishing pad. The non-contact pad cleaning device.

19. The non-contact pad cleaning device according to claim 18, further comprising a fine bubble generator connected to the liquid supply line.

20. The non-contact pad cleaning device according to claim 18, further comprising a liquid heating device connected to the liquid supply line for heating the liquid flowing through the liquid supply line.

21. The non-contact pad cleaning device according to claim 18, further comprising a pad cleaning nozzle for forming a jet of liquid discharge fluid for guiding the liquid contained in the two-fluid on the polishing surface of the polishing pad to the outer periphery of the polishing pad.

22. a liquid discharge fluid line for supplying liquid discharge fluid to the pad cleaning nozzle, The non-contact pad cleaning device according to claim 21, further comprising a fine bubble generator connected to the liquid discharge fluid line.

23. The pad cleaning nozzle is arranged downstream of the two-fluid nozzle in the rotation direction of the polishing pad. The non-contact pad cleaning device according to claim 21.

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