Non-contact pad cleaning device

Abstract

The present invention provides a non-contact pad cleaning device that can improve the cleaning effect of the polishing surface by preventing the liquid supplied to the polishing surface of the polishing pad from accumulating on the polishing surface. [Solution] The polishing surface cleaning device 8 comprises a plurality of two-fluid nozzles 9 that eject two-fluid jets, an upstream nozzle cover 41 and a downstream nozzle cover 42. The upstream nozzle cover 41 is positioned upstream of the plurality of two-fluid nozzles 9 in the rotational direction of the polishing pad 2, and the downstream nozzle cover 42 is positioned downstream of the plurality of two-fluid nozzles 9 in the rotational direction of the polishing pad 2. The distance D1 from the polishing surface 2a to the lower end 41c of the upstream nozzle cover 41 is greater than the distance D2 from the polishing surface 2a to the lower end 42c of the downstream nozzle cover 42.

Description

Technical Field

[0001] The present invention relates to a non-contact pad cleaning device for cleaning a 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 apparatus is an apparatus 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 scraping 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 from an atomizer to the polishing surface, and the foreign substances are washed away from the polishing pad with pure water. Since the pure water collides forcefully with the polishing surface of the polishing pad, a splash prevention cover is attached to the atomizer to prevent the scattering of the pure water (see Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the pure water guided from the atomizer to the polishing surface of the polishing pad is dragged along the polishing surface of the rotating pad and collides with the jet of pure water, forming a water film on the polishing surface. This water film is blocked by the jet of pure water and the splash-proof cover, increasing its thickness. This water film on the polishing surface may obstruct the jet of pure water from the atomizer to the polishing surface, potentially reducing the cleaning effect of the polishing surface.

[0006] Therefore, the present invention provides a non-contact pad cleaning device that can improve the cleaning effect of the polishing surface by preventing the liquid supplied to the polishing surface of the polishing pad from accumulating on the polishing surface. [Means for solving the problem]

[0007] In one embodiment, a non-contact pad cleaning device is provided for cleaning the polishing surface of a polishing pad for polishing a workpiece without contact, comprising: a rotary table for rotating the polishing pad; a polishing surface cleaning device having a plurality of two-fluid nozzles for ejecting two-fluid jets toward the polishing surface of the polishing pad; a liquid supply line and a gas supply line connected to the plurality of two-fluid nozzles, wherein the polishing surface cleaning device comprises a plurality of two-fluid nozzles, each having a plurality of nozzles for ejecting two-fluid jets; a nozzle carrier for holding the plurality of two-fluid nozzles; and an upstream nozzle cover and a downstream nozzle cover fixed to the nozzle carrier, wherein the plurality of nozzles are arranged at different distances from the center of the polishing pad; the upstream nozzle cover is positioned upstream of the plurality of two-fluid nozzles in the rotational direction of the polishing pad; the downstream nozzle cover is positioned downstream of the plurality of two-fluid nozzles in the rotational direction of the polishing pad; and the distance from the polishing surface to the lower end of the upstream nozzle cover is greater than the distance from the polishing surface to the lower end of the downstream nozzle cover.

[0008] In one embodiment, the distance from the polishing surface to the lower end of the upstream nozzle cover is within the range of 10 mm to 20 mm. In one embodiment, the distance from the polishing surface to the lower end of the downstream nozzle cover is within the range of 3 mm to 9 mm. In one embodiment, the outer end of the upstream nozzle cover and the outer end of the downstream nozzle cover are located radially outward from the outer edge of the polishing pad. In one embodiment, the polishing surface cleaning device further includes an outer cover connected to the outer end of the upstream nozzle cover and the outer end of the downstream nozzle cover. In one embodiment, the polishing surface cleaning device further includes an inner cover connected to the inner end of the upstream nozzle cover and the inner end of the downstream nozzle cover. In one embodiment, the width of the upstream nozzle cover in a direction perpendicular to the longitudinal direction of the nozzle carrier is greater than the width of the downstream nozzle cover in a direction perpendicular to the longitudinal direction of the nozzle carrier.

[0009] In one embodiment, each of the plurality of nozzles is parallel to the longitudinal direction of the nozzle carrier. In one embodiment, the non-contact pad cleaning device further includes a nozzle oscillation mechanism that oscillates the polishing surface cleaning device above the polishing pad. In one embodiment, the non-contact pad cleaning device further comprises an operation control unit that controls the operation of the nozzle oscillation mechanism, the operation control unit is configured to give a command to the nozzle oscillation mechanism to oscillate the polishing surface cleaning device above the polishing pad at a preset oscillation angle, and the preset oscillation angle is changeable. In one embodiment, the upstream nozzle cover is inclined downward toward the upstream side in the rotational direction of the rotary table, and the downstream nozzle cover is inclined downward toward the downstream side in the rotational direction of the rotary table. In one embodiment, the plurality of nozzles are inclined at different angles with respect to the longitudinal direction of the nozzle carrier. In one embodiment, the plurality of nozzles are each located on a plurality of straight lines passing through the center of the polishing pad when viewed from above the polishing pad. In one embodiment, the non-contact pad cleaning device further includes a cover inner surface cleaning device for cleaning the inner surfaces of the upstream nozzle cover and the downstream nozzle cover. In one embodiment, the non-contact pad cleaning device further includes a cover exterior cleaning device for cleaning the outer surfaces of the upstream nozzle cover and the downstream nozzle cover. [Effects of the Invention]

[0010] The jets of two fluids ejected from the two-fluid nozzle collide with the polishing surface of the polishing pad, and the liquids in the two fluids then flow upstream and downstream over the polishing surface. Some of the liquid flowing upstream is dragged back by the polishing surface of the rotating polishing pad and is blocked by the jets of two fluids ejected from the two-fluid nozzle. As a result, a liquid film is formed between the two-fluid jets and the lower end of the upstream nozzle cover. Since the distance between the lower end of the upstream nozzle cover and the polishing surface is large, the liquid film does not easily come into contact with the lower end of the upstream nozzle cover. Therefore, the liquid flowing upstream can pass through the gap between the lower end of the upstream nozzle cover and the polishing surface. Some of the liquid film is carried by the liquid flowing upstream and flows out through the gap between the lower end of the upstream nozzle cover and the polishing surface. Other parts of the liquid film flow radially outward from the polishing pad and are discharged from the polishing surface. Therefore, the thickness of the liquid film does not become large. As a result, the jets of two fluids ejected from the two-fluid nozzle collide with the polishing surface of the polishing pad without being obstructed by a liquid film, thereby cleaning the polishing surface. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing one embodiment of a polishing apparatus equipped with a non-contact pad cleaning device. [Figure 2] This is a top view showing one embodiment of a non-contact pad cleaning device. [Figure 3] This is a view of the polishing surface cleaning device from below. [Figure 4] This is a cross-sectional view along line AA in Figure 2. [Figure 5]This is a diagram showing a comparative example in which the distance from the polishing surface of the polishing pad to the lower end of the upstream nozzle cover is the same as the distance from the polishing surface to the lower end of the downstream nozzle cover. [Figure 6] This is a diagram showing an embodiment in which the distance from the polishing surface of the polishing pad to the lower end of the upstream nozzle cover is greater than the distance from the polishing surface to the lower end of the downstream nozzle cover. [Figure 7] This is a diagram showing an embodiment in which the upstream nozzle cover and the downstream nozzle cover are fixed to both side surfaces of the nozzle carrier. [Figure 8] This is a diagram for explaining the velocity vectors of a part of the liquid spread on the polishing surface after the jets of the two fluids collide with the polishing surface and the velocity vectors of the liquid on the polishing surface of the rotating polishing pad. [Figure 9] This is a top view for explaining an embodiment in which a polishing surface cleaning device including a plurality of two-fluid nozzles is swung above the polishing surface of a polishing pad. [Figure 10] This is a diagram showing an embodiment of the arrangement of the plurality of ejection openings of a plurality of two-fluid nozzles. [Figure 11] This is a diagram showing another embodiment of the plurality of ejection openings of a plurality of two-fluid nozzles. [Figure 12] This is a diagram showing yet another embodiment of the plurality of ejection openings of a plurality of two-fluid nozzles. [Figure 13] This is a diagram showing yet another embodiment of the plurality of ejection openings of a plurality of two-fluid nozzles. [Figure 14] This is a top view showing another embodiment of the upstream nozzle cover and the downstream nozzle cover. [Figure 15] This is a cross-sectional view taken along line B-B of FIG. 14. [Figure 16] This is a cross-sectional view showing yet another embodiment of the upstream nozzle cover and the downstream nozzle cover. [Figure 17] This is a cross-sectional view showing yet another embodiment of the upstream nozzle cover and the downstream nozzle cover. [Figure 18] This is a cross-sectional view showing yet another embodiment of the upstream nozzle cover and the downstream nozzle cover. [Figure 19]This is a top view showing yet another embodiment of the non-contact pad cleaning device. [Figure 20] This is a top view illustrating the operation of moving the polishing surface cleaning device from a position above the polishing surface to a position above multiple cleaning nozzles. [Figure 21] This figure shows how multiple cleaning nozzles are releasing cleaning fluid onto the inner surfaces of the upstream and downstream nozzle covers. [Figure 22] This is a top view showing yet another embodiment of the non-contact pad cleaning device. [Figure 23] This is a top view illustrating the operation of moving the polishing surface cleaning device from a position above the polishing surface to a position below the multiple cleaning nozzles. [Figure 24] This figure shows how multiple cleaning nozzles are discharging cleaning fluid onto the outer surfaces of the upstream and downstream nozzle covers. [Figure 25] This is a top view showing yet another embodiment of the non-contact pad cleaning device. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic diagram showing one embodiment of a polishing apparatus equipped with a non-contact pad cleaning device. The polishing apparatus is a device for chemically and mechanically polishing a wafer W, which is an example of a workpiece used in the manufacture of semiconductor devices. As shown in Figure 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 slurry supply nozzle 10 that supplies slurry to the polishing surface 2a, and a polishing surface cleaning device 8 that cleans the polishing surface 2a of the polishing pad 2. The polishing surface cleaning device 8 is positioned above the polishing surface 2a of the polishing pad 2 and faces the polishing surface 2a.

[0013] The polishing head 7 is configured to hold a 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 a workpiece, but the workpiece is not limited to a wafer and may be a circular substrate, rectangular substrate, wiring board, panel, etc., used in the manufacture of semiconductor devices.

[0014] The polishing device further comprises a support shaft 14, a polishing head oscillating 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 oscillating 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) equipped with an electric motor or the like is arranged inside the polishing head oscillating 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.

[0015] The polishing head shaft 18 is connected to a polishing head lifting mechanism (including a ball screw mechanism, etc.) not shown. This polishing head lifting mechanism is configured to move the polishing head shaft 18 up and down relative to the polishing head oscillating arm 16. This up and down movement of the polishing head shaft 18 allows the polishing head 7 to move up and down relative to the polishing head oscillating arm 16 and the rotary table 5, as indicated by the arrows.

[0016] The polishing apparatus further includes a table rotation motor 21 that rotates the polishing pad 2 and the rotary table 5 around their respective axes. The table rotation motor 21 is located below the rotary table 5, and the rotary table 5 is connected to the table rotation motor 21 via a table axis 5a. The rotary table 5 and the polishing pad 2 are rotated by the table rotation motor 21 around the table axis 5a in the direction indicated by the arrow. The polishing pad 2 is attached to the upper surface of the rotary table 5. The exposed surface of the polishing pad 2 constitutes the polishing surface 2a for polishing the wafer W.

[0017] The wafer W is polished as follows: The wafer W is held in the polishing head 7 with its surface to be polished facing downwards. While the polishing head 7 and the rotary table 5 are rotated, slurry is supplied from the slurry supply nozzle 10 located 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 around its central axis. The polishing head 7 is moved to a predetermined height by a polishing head lifting mechanism (not shown). Furthermore, while the polishing head 7 is maintained at the predetermined height, the wafer W is pressed against the polishing surface 2a of the polishing pad 2. The wafer W is rotated by the polishing head 7. With the slurry present on the polishing surface 2a of the polishing pad 2, the wafer W is slid against the polishing surface 2a. The surface of the wafer W is polished by a combination of the chemical action of the slurry and the mechanical action of the abrasive grains contained in the slurry and / or the polishing pad 2.

[0018] The polishing apparatus includes a dresser 22 for dressing the polishing surface 2a of the polishing pad 2. The dresser 22 comprises a dressing disc 23 that slides against the polishing surface 2a of the polishing pad 2, a dresser shaft 24 to which the dressing disc 23 is connected, and a dresser swing arm 25 that rotatably supports the dresser shaft 24. The lower surface of the dressing disc 23 constitutes a dressing surface 23a, and this dressing surface 23a is made up of abrasive grains (for example, diamond particles).

[0019] The dresser shaft 24 is connected to a disc pressing mechanism (including, for example, an air cylinder) located within the dresser oscillating arm 25. This disc pressing mechanism is configured to press the dressing surface 23a of the dressing disc 23 against the polishing surface 2a of the polishing pad 2 via the dresser shaft 24. Furthermore, the dresser shaft 24 is connected to a disc rotation mechanism (including, for example, an electric motor) located within the dresser oscillating arm 25. This disc rotation mechanism is configured to rotate the dressing disc 23 via the dresser shaft 24 in the direction indicated by the arrow.

[0020] The polishing surface 2a of the polishing pad 2 is dressed as follows: The polishing pad 2 is rotated together with the rotary table 5 by the table rotation motor 21. The dressing disc 23 is rotated around the dresser shaft 24 by a disk rotation mechanism (not shown), and the dressing surface 23a of the dressing disc 23 is pressed against the polishing surface 2a by a disk pressing mechanism (not shown), and slides against the polishing surface 2a. While the dressing disc 23 is rotating, the dresser swing arm 25 is swung around the pivot shaft 28 to swing the dressing disc 23 radially over the polishing surface 2a. In this way, the polishing pad 2 is slightly scraped off by the dressing disc 23, and the polishing surface 2a is dressed (regenerated). The dressing of the polishing surface 2a of the polishing pad 2 is performed during or after the polishing of the wafer W.

[0021] The polishing apparatus includes an operation control unit 30 that controls the operation of the polishing apparatus, including the polishing and dressing operations 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 unit 30b that performs calculations according to the instructions contained in the program. The storage device 30a includes a main memory such as random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) or solid state drive (SSD). Examples of processing units 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.

[0022] Next, a non-contact pad cleaning device for cleaning the polishing surface 2a of the polishing pad 2 will be described. Figure 2 is a top view showing one embodiment of the non-contact pad cleaning device, Figure 3 is a view of the polishing surface cleaning device 8 from below, and Figure 4 is a cross-sectional view taken along line AA in Figure 2. The non-contact pad cleaning device for cleaning the polishing surface 2a of the polishing pad 2 without contact comprises a polishing surface cleaning device 8 having a plurality of two-fluid nozzles 9 that eject two fluids toward the polishing surface 2a of the polishing pad 2, and a liquid supply line 33 and a gas supply line 34 connected to the plurality of two-fluid nozzles 9.

[0023] In the embodiment shown in Figure 2, the non-contact pad cleaning device further comprises the rotary table 5 and motion control unit 30 shown in Figure 1. The rotary table 5 and motion control unit 30 constitute a part of the non-contact pad cleaning device, but at the same time also constitute a part of the polishing device shown in Figure 1.

[0024] Multiple two-fluid nozzles 9 are positioned at different distances from the center CP of the polishing pad 2. In the embodiment shown in Figure 2, the multiple two-fluid nozzles 9 are arranged radially to the polishing pad 2. That is, when viewed from above the polishing pad 2, the multiple two-fluid nozzles 9 are positioned on a straight line RL that passes through the center CP of the polishing pad 2 and extends radially to the polishing pad 2. The straight line RL is a dashed line. The multiple two-fluid nozzles 9 are located above the polishing surface 2a of the polishing pad 2. The outermost two-fluid nozzle 9 of the multiple two-fluid nozzles 9 is located radially inward from the outer edge of the polishing pad 2.

[0025] Each of the two-fluid nozzles 9 has multiple outlets 9a from which two fluids are ejected. The polishing surface cleaning device 8 further comprises a nozzle carrier 35 that holds the multiple two-fluid nozzles 9, and an upstream nozzle cover 41 and a downstream nozzle cover 42 fixed to the nozzle carrier 35. The multiple outlets 9a are arranged at different distances from the center CP of the polishing pad 2. The nozzle carrier 35 is held by a holding arm 44, which is connected to a nozzle swing mechanism 38. Liquid supply lines 33 and gas supply lines 34 extend through the holding arm 44 and nozzle carrier 35 and communicate with the multiple two-fluid nozzles 9.

[0026] Liquids and gases are supplied to a plurality of two-fluid nozzles 9 through a liquid supply line 33 and a gas supply line 34, and are mixed within each two-fluid nozzle 9 to form a two-fluid jet, which is a mixed fluid of liquid and gas. The two-fluid jet is ejected from a plurality of outlets 9a of the plurality of two-fluid nozzles 9 onto the polishing surface 2a of the polishing pad 2. Examples of liquids supplied from the liquid supply line 33 to the plurality of two-fluid nozzles 9 include pure water and pure water containing fine bubbles. Examples of gases supplied from the gas supply line 34 to the plurality of two-fluid nozzles 9 include air and inert gases (e.g., nitrogen gas). The liquid supply line 33 and the gas supply line 34 are connected to a liquid supply source (not shown) and a gas supply source (not shown), respectively.

[0027] Each two-fluid nozzle 9 has a slit-shaped outlet 9a that forms a fan-shaped jet of two fluids. As shown in Figure 3, in this embodiment, each of the multiple outlets 9a is parallel to the longitudinal direction of the nozzle carrier 35. More specifically, each outlet 9a is parallel to a straight line RL that passes through the center CP of the polishing pad 2 and extends radially across the polishing pad 2. The multiple outlets 9a are arranged along the longitudinal direction of the nozzle carrier 35, and the jet of two fluids is ejected onto the polishing surface 2a of the polishing pad 2 to clean the polishing surface 2a.

[0028] A jet of two fluids, a mixture of liquid and gas, delivers a stronger impact to the polishing surface 2a of the polishing pad 2 compared to a jet of liquid alone. Therefore, it can remove polishing debris and abrasive particles from the slurry through the numerous holes formed on the polishing surface 2a of the polishing pad 2. On the other hand, the liquid contained in the two fluids is prone to scattering when the two-fluid jet collides with the polishing surface 2a. Since the liquid contains polishing debris and slurry, if the scattered liquid comes into contact with the polishing surface 2a of the polishing pad 2 again, it may adversely affect the polishing of the wafer.

[0029] Therefore, in this embodiment, the polishing surface cleaning device 8 is equipped with an upstream nozzle cover 41 and a downstream nozzle cover 42 to prevent liquid splashing. The upstream nozzle cover 41 and the downstream nozzle cover 42 are fixed to the nozzle carrier 35. The upstream nozzle cover 41 and the downstream nozzle cover 42 are positioned on both sides of the plurality of two-fluid nozzles 9. That is, the upstream nozzle cover 41 is positioned upstream of the plurality of two-fluid nozzles 9 in the rotational direction of the polishing pad 2, and the downstream nozzle cover 42 is positioned downstream of the plurality of two-fluid nozzles 9 in the rotational direction of the polishing pad 2. The upstream nozzle cover 41 and the downstream nozzle cover 42 extend along the arrangement direction of the plurality of two-fluid nozzles 9.

[0030] The inner end 41a of the upstream nozzle cover 41 is located between the center CP of the polishing pad 2 and the innermost two-fluid nozzle 9 among the multiple two-fluid nozzles 9. The outer end 41b of the upstream nozzle cover 41 is located radially outward from the outer edge of the polishing pad 2. The polishing surface cleaning device 8 of this embodiment further includes an inner cover 47 connected to the inner end 41a of the upstream nozzle cover 41 and the inner end 42a of the downstream nozzle cover 42. The inner cover 47 is located radially inward from the multiple two-fluid nozzles 9.

[0031] Because the peripheral velocity of the outer circumference of the polishing pad 2 is high, a large amount of liquid is likely to be scattered when the two-fluid jets collide with the outer circumference of the polishing pad 2. Furthermore, the liquid on the polishing surface 2a is scattered from the outer edge of the polishing pad 2 due to centrifugal force. To catch this scattered liquid, the polishing surface cleaning device 8 of this embodiment is equipped with an outer cover 48 connected to the outer end 41b of the upstream nozzle cover 41 and the outer end 42b of the downstream nozzle cover 42. The outer cover 48 is located radially outward from the plurality of two-fluid nozzles 9 and radially outward from the outer edge of the polishing pad 2. In one embodiment, the outer end 41b of the upstream nozzle cover 41, the outer end 42b of the downstream nozzle cover 42, and the outer cover 48 are located at least 15 mm away from the outer edge of the polishing pad 2 in the radial direction.

[0032] In one embodiment, the upstream nozzle cover 41, the downstream nozzle cover 42, the inner cover 47, and the outer cover 48 are a single integrated structure and are connected without gaps. The upstream nozzle cover 41, the downstream nozzle cover 42, the inner cover 47, and the outer cover 48 together form a rectangular cover structure that encloses the entirety of the multiple two-fluid nozzles 9 and the nozzle carrier 35. Therefore, the upstream nozzle cover 41, the downstream nozzle cover 42, the inner cover 47, and the outer cover 48 can prevent splashing of liquid when the two-fluid jets collide with the polishing surface 2a of the polishing pad 2.

[0033] Since the outer end 41b of the upstream nozzle cover 41, the outer end 42b of the downstream nozzle cover 42, and the outer cover 48 are located radially outward from the outer edge of the polishing pad 2, some of the liquid that comes into contact with the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42 flows radially outward along the upstream nozzle cover 41 and the downstream nozzle cover 42 and is discharged from the polishing surface 2a.

[0034] As shown in Figure 4, the distance D1 from the polishing surface 2a of the polishing pad 2 to the lower end 41c of the upstream nozzle cover 41 is greater than the distance D2 from the polishing surface 2a to the lower end 42c of the downstream nozzle cover 42. In one embodiment, the distance D1 is in the range of 10 mm to 20 mm, and the distance D2 is in the range of 3 mm to 9 mm. The reason why the distance D1 is greater than the distance D2 will be explained with reference to Figures 5 and 6.

[0035] Figure 5 shows a comparative example in which the distance from the polishing surface 2a of the polishing pad 2 to the lower end 41c of the upstream nozzle cover 41 is the same as the distance from the polishing surface 2a to the lower end 42c of the downstream nozzle cover 42. As shown in Figure 5, the jet of two fluids ejected from the two-fluid nozzle 9 collides with the polishing surface 2a of the polishing pad 2, and then the liquid in the two fluids flows upstream and downstream over the polishing surface 2a. The liquid flowing downstream passes through the gap between the lower end 42c of the downstream nozzle cover 42 and the polishing surface 2a. The liquid flowing upstream also passes through the gap between the lower end 41c of the upstream nozzle cover 41 and the polishing surface 2a, but some of the liquid is dragged back by the polishing surface 2a of the rotating polishing pad 2 and is blocked by the jet of two fluids ejected from the two-fluid nozzle 9. As a result, a liquid film is formed between the jet of two fluids and the lower end 41c of the upstream nozzle cover 41.

[0036] If the distance from the polishing surface 2a of the polishing pad 2 to the lower end 41c of the upstream nozzle cover 41 is small, as shown in Figure 5, the liquid film will come into contact with the lower end 41c of the upstream nozzle cover 41, blocking the gap between the polishing surface 2a and the lower end 41c of the upstream nozzle cover 41. As a result, the liquid flowing upstream will have difficulty passing through the gap between the polishing surface 2a and the lower end 41c of the upstream nozzle cover 41, and the amount (thickness) of the liquid film between the two-fluid nozzle 9 and the upstream cover 41 will increase. A portion of the two-fluid jet ejected from the two-fluid nozzle 9 will be obstructed by the liquid film and will not be able to collide with the polishing surface 2a of the polishing pad 2. As a result, the desired cleaning result of the polishing surface 2a cannot be obtained.

[0037] Figure 6 shows one embodiment in which the distance from the polishing surface 2a of the polishing pad 2 to the lower end 41c of the upstream nozzle cover 41 is greater than the distance from the polishing surface 2a to the lower end 42c of the downstream nozzle cover 42. As shown in Figure 6, the distance between the lower end 41c of the upstream nozzle cover 41 and the polishing surface 2a is large, so the liquid film is less likely to come into contact with the lower end 41c of the upstream nozzle cover 41. In particular, when the distance between the lower end 41c of the upstream nozzle cover 41 and the polishing surface 2a is in the range of 10 mm to 20 mm, the liquid film is less likely to come into contact with the lower end 41c of the upstream nozzle cover 41.

[0038] Therefore, the liquid flowing upstream can pass through the gap between the lower end 41c of the upstream nozzle cover 41 and the polishing surface 2a. A portion of the liquid film is carried by the liquid flowing upstream and flows out through the gap between the lower end 41c of the upstream nozzle cover 41 and the polishing surface 2a. The other portion of the liquid film flows radially outward from the polishing pad 2 and is discharged from the polishing surface 2a. Therefore, the thickness of the liquid film does not increase. As a result, the jets of two fluids ejected from the two-fluid nozzle 9 collide with the polishing surface 2a of the polishing pad 2 without being obstructed by the liquid film, and the polishing surface 2a can be cleaned.

[0039] On the other hand, from the viewpoint of preventing droplets from passing through when the two-fluid jet from the two-fluid nozzle 9 collides with the polishing surface 2a, it is preferable that the distance D2 from the polishing surface 2a to the lower end 42c of the downstream nozzle cover 42 be small. Therefore, in one embodiment, the distance D2 is in the range of 3 mm to 9 mm.

[0040] In the embodiment shown in Figure 4, the upstream nozzle cover 41 and the downstream nozzle cover 42 are fixed to the upper surface 35a of the nozzle carrier 35, and the upstream nozzle cover 41 and the downstream nozzle cover 42 are connected to each other at the upper surface 35a of the nozzle carrier 35, forming an integrated structure.

[0041] In one embodiment, as shown in Figure 7, the upstream nozzle cover 41 and the downstream nozzle cover 42 may be fixed to both sides 35b and 35c of the nozzle carrier 35, respectively. The embodiment shown in Figure 7 allows for a reduction in the surface area of ​​the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42. Droplets bounced back from the polishing surface 2a of the polishing pad 2 contain polishing debris and slurry. Droplets containing polishing debris and slurry adhere to the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42. According to this embodiment, since the surface area of ​​the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42 is small, the amount of droplets adhering to the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42 is reduced. Furthermore, it is easier to clean the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42.

[0042] Figure 8 illustrates the velocity vectors of some of the liquid that spreads on the polishing surface 2a after the two-fluid jets collide with the polishing surface 2a, and the velocity vectors of the liquid on the polishing surface 2a of the rotating polishing pad 2. When the two-fluid jets ejected from the two-fluid nozzle 9 collide with the polishing surface 2a, the liquid in the two fluids spreads on the polishing surface 2a. The white arrows in Figure 8 represent the velocity vector V1 of some of the liquid that spreads on the polishing surface 2a after the two-fluid jets collide with the polishing surface 2a. The black arrows in Figure 8 represent the velocity vector V2 of the liquid dragged along the polishing surface 2a of the rotating polishing pad 2. Velocity vectors V1 and V2 are perpendicular to the radial direction of the polishing pad 2 and point in opposite directions to each other.

[0043] The dotted ellipse T shown in Figure 8 represents the liquid contact area where the jet of two fluids ejected from the nozzle 9a of the two-fluid nozzle 9 collides with the polishing surface 2a. Since the jet of two fluids ejected from the two-fluid nozzle 9 is fan-shaped, the liquid contact area T on the polishing surface 2a is elliptical. The larger the velocity vectors V1 and V2, the more likely the liquid is to splatter. As shown in Figure 8, the velocity vector V2 increases with distance from the center CP of the polishing pad 2. Therefore, the liquid is likely to splatter around the outer circumference of the polishing pad 2. The upstream nozzle cover 41 and the downstream nozzle cover 42 are positioned upstream and downstream of all two-fluid nozzles 9, including the outermost two-fluid nozzle 9, so that liquid splatter can be prevented.

[0044] The magnitude of the velocity vector V1 is minimized when the nozzle 9a of each two-fluid nozzle 9 is parallel to the radial direction of the polishing pad 2 (parallel to the straight line RL). Therefore, from the viewpoint of minimizing liquid splashing, the arrangement of the nozzles 9a of the two-fluid nozzle 9 shown in Figure 8 is desirable. On the other hand, as shown in Figure 8, there is a gap between adjacent liquid contact areas T. This indicates that there are areas where the two-fluid jets do not collide. In areas where the two-fluid jets do not collide, polishing debris and slurry may not be removed.

[0045] Therefore, in order to eliminate areas where the two fluid jets do not collide, in one embodiment, as shown in Figure 9, the operation control unit 30 commands the nozzle oscillation mechanism 38 to oscillate the polishing surface cleaning device 8, which includes a plurality of two-fluid nozzles 9, an upstream nozzle cover 41, a downstream nozzle cover 42, an inner cover 47, and an outer cover 48, at an oscillation angle θ above the polishing surface 2a of the polishing pad 2. As the plurality of two-fluid nozzles 9 move above the polishing surface 2a and eject two fluid jets onto the polishing surface 2a, the plurality of two-fluid nozzles 9 can guide the two fluid jets over the entire polishing surface 2a.

[0046] The oscillation angle θ is set and can be changed by the motion control unit 30. In one embodiment, the oscillation angle θ can be changed within the range of 0 to 45 degrees. When the oscillation angle θ is small, a large amount of the two-fluid mixture can be supplied to the central region of the polishing surface 2a of the polishing pad 2, making it easier to maintain a wet state of the polishing surface 2a. On the other hand, when the oscillation angle θ is large, the jets of the two-fluid mixture ejected from the multiple two-fluid nozzles 9 push polishing debris, slurry, and the liquid contained in the two-fluid mixture itself to the outside of the polishing pad 2, making it easier to discharge them from the polishing pad 2. In addition, the liquid film, as explained with reference to Figure 6, becomes thinner, allowing the jets of the two-fluid mixture to collide with the polishing surface 2a of the polishing pad 2. As a result, the cleaning effect of the polishing pad 2 is improved.

[0047] In one embodiment, as shown in Figure 10, the multiple two-fluid nozzles 9 do not have to be arranged radially around the polishing pad 2. In the example shown in Figure 10, when viewed from above the polishing pad 2, the multiple nozzles 9a of the multiple two-fluid nozzles 9 are arranged parallel to a straight line RL extending radially around the polishing pad 2, but they are not on the straight line RL. In this arrangement, the velocity vector V1 of the liquid when the two-fluid jets collide with the polishing surface 2a is slightly larger than that of the embodiment shown in Figure 8, but in the outer periphery of the polishing pad 2 where liquid splashing is likely to occur, the velocity vector V1 is approximately the same as that of the embodiment shown in Figure 8. Furthermore, although not shown in Figure 10, the upstream nozzle cover 41 and the downstream nozzle cover 42 are positioned upstream and downstream of all two-fluid nozzles 9, including the outermost two-fluid nozzle 9, so that the upstream nozzle cover 41 and the downstream nozzle cover 42 can prevent liquid splashing.

[0048] In the embodiment shown in Figure 10, as described with reference to Figure 9, the operation control unit 30 may give a command to the nozzle oscillation mechanism 38 to oscillate the polishing surface cleaning device 8, which includes a plurality of two-fluid nozzles 9, above the polishing surface 2a of the polishing pad 2 at a preset oscillation angle.

[0049] Figure 11 shows another embodiment of the multiple outlets 9a of the multiple bifluid nozzles 9. In the embodiment shown in Figure 11, the multiple outlets 9a of the multiple bifluid nozzles 9 are inclined with respect to the radial direction of the polishing pad 2. That is, each outlet 9a is inclined with respect to the straight line RL passing through the center CP of the polishing pad 2. In one embodiment, each outlet 9a is inclined within a range of 5 to 15 degrees with respect to the straight line RL passing through the center CP of the polishing pad 2. The liquid contact area T where the jets of bifluid ejected from the multiple outlets 9a collide with the polishing surface 2a of the polishing pad 2 is also inclined with respect to the radial direction (i.e., the straight line RL) of the polishing pad 2.

[0050] Multiple liquid contact areas T are separated from each other, and there are gaps between adjacent liquid contact areas T. The liquid dragged along the polishing surface 2a of the rotating polishing pad 2 can pass through the gaps between the liquid contact areas T. Therefore, a liquid film is less likely to form upstream of the multiple two-fluid nozzles 9. Furthermore, the multiple liquid contact areas T overlap in a direction perpendicular to the radial direction of the polishing pad 2 (a direction perpendicular to the straight line RL). Therefore, when the polishing pad 2 is rotating, the two-fluid jets can clean the entire target cleaning area within the polishing surface 2a without oscillating the multiple two-fluid nozzles 9. In the embodiment shown in Figure 11, the nozzle oscillating mechanism 38 shown in Figure 2 may not be provided.

[0051] On the other hand, the velocity vector V1 of the liquid when the two-fluid jets collide with the polishing surface 2a is slightly larger than that of the embodiment shown in Figure 8. This is because each liquid contact area T is inclined with respect to the radial direction of the polishing pad 2, and the velocity component in the direction perpendicular to the radial direction is large. However, since the upstream nozzle cover 41 and the downstream nozzle cover 42 are positioned upstream and downstream of all two-fluid nozzles 9, splashing of the liquid can be prevented.

[0052] Figure 12 shows yet another embodiment of the multiple outlets 9a of the multiple two-fluid nozzles 9. In the embodiment shown in Figure 12, the multiple outlets 9a are inclined at different angles with respect to the longitudinal direction of the nozzle carrier 35. These outlets 9a are arranged along an arc. Furthermore, when viewed from above the polishing pad 2, the multiple outlets 9a are each located on multiple straight lines RL that pass through the center CP of the polishing pad 2 and extend radially across the polishing pad 2. Each outlet 9a is parallel to the corresponding straight line RL. That is, the multiple outlets 9a are parallel to multiple radial directions of the polishing pad 2.

[0053] With this arrangement, the velocity vector V1 of the liquid when the two-fluid jets collide with the polishing surface 2a is the same magnitude as in the embodiment shown in Figure 8, and splashing of the liquid can be suppressed. The multiple liquid contact areas T overlap in a direction perpendicular to the radial direction of the polishing pad 2 (a direction perpendicular to the straight line RL). Therefore, when the polishing pad 2 is rotating, the two-fluid jets can clean the entire target cleaning area within the polishing surface 2a without oscillating the multiple two-fluid nozzles 9.

[0054] Figure 13 shows yet another embodiment of the multiple outlets 9a of the multiple two-fluid nozzles 9. The embodiment shown in Figure 13 is the same as the embodiment described with reference to Figure 12 in that the multiple outlets 9a are inclined at different angles with respect to the longitudinal direction of the nozzle carrier 35 and are each located on multiple straight lines RL extending radially from the polishing pad 2, but differs in that the multiple outlets 9a are arranged linearly along the longitudinal direction of the nozzle carrier 35.

[0055] In this embodiment as well, the velocity vector V1 of the liquid when the two-fluid jets collide with the polishing surface 2a is the same magnitude as in the embodiment shown in Figure 8, and liquid splashing can be suppressed. Furthermore, since the multiple liquid contact areas T overlap in a direction perpendicular to the radial direction of the polishing pad 2 (a direction perpendicular to the straight line RL), the two-fluid jets can clean the entire target cleaning area within the polishing surface 2a without having to oscillate the multiple two-fluid nozzles 9.

[0056] Figure 14 is a top view showing another embodiment of the upstream nozzle cover 41 and the downstream nozzle cover 42, and Figure 15 is a cross-sectional view taken along line BB of Figure 14. The configuration of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 1 to 4, so a redundant explanation is omitted. In this embodiment, the width W1 of the upstream nozzle cover 41 in the direction perpendicular to the longitudinal direction of the nozzle carrier 35 is greater than the width W2 of the downstream nozzle cover 42 in the direction perpendicular to the longitudinal direction of the nozzle carrier 35. The width W1 of the upstream nozzle cover 41 is the distance from the upstream side surface 35b of the nozzle carrier 35 to the upstream nozzle cover 41, and the width W2 of the downstream nozzle cover 42 is the distance from the downstream side surface 35c of the nozzle carrier 35 to the downstream nozzle cover 42.

[0057] According to this embodiment, since the width W1 of the upstream nozzle cover 41 is large, when the jet of two fluids ejected from the two-fluid nozzle 9 collides with the polishing surface 2a, the droplets that bounce back from the polishing surface 2a have difficulty passing through the gap between the lower end 41c of the upstream nozzle cover 41 and the polishing surface 2a. In other words, the upstream nozzle cover 41 can catch most of the droplets that bounce back from the polishing surface 2a.

[0058] Figure 16 is a cross-sectional view showing yet another embodiment of the upstream nozzle cover 41 and the downstream nozzle cover 42. The configuration of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 1 to 4, so a redundant explanation will be omitted. In this embodiment, the upstream nozzle cover 41 is inclined downward toward the upstream side in the rotational direction of the rotary table 5, and the downstream nozzle cover 42 is inclined downward toward the downstream side in the rotational direction of the rotary table 5.

[0059] When the jet of two fluids ejected from the two-fluid nozzle 9 collides with the polishing surface 2a of the polishing pad 2, the liquid bounces off the polishing surface 2a and is received by the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42. Since the upstream nozzle cover 41 and the downstream nozzle cover 42 are inclined downward toward their lower ends 41c and 42c, the liquid flows downward along the inclined inner surfaces and falls onto the polishing surface 2a. Therefore, it is possible to prevent polishing debris and slurry contained in the liquid from remaining on the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42. Furthermore, even if liquid splashes onto the outer surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42, the liquid flows downward along the inclined outer surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42 and falls onto the polishing surface 2a. Therefore, it is possible to prevent polishing debris and slurry contained in the liquid from remaining on the outer surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42.

[0060] Figures 17 and 18 are cross-sectional views showing yet another embodiment of the upstream nozzle cover 41 and the downstream nozzle cover 42. The configuration of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 1 to 4, so a redundant description will be omitted. In the embodiment shown in Figures 17 and 18, the upstream nozzle cover 41 and the downstream nozzle cover 42 have a wing shape.

[0061] In Figure 17, the upstream nozzle cover 41 and the downstream nozzle cover 42 have the same shape. In Figure 18, the width W1 of the upstream nozzle cover 41 in the direction perpendicular to the longitudinal direction of the nozzle carrier 35 is greater than the width W2 of the downstream nozzle cover 42 in the direction perpendicular to the longitudinal direction of the nozzle carrier 35.

[0062] In the embodiments shown in Figures 17 and 18, the width of the upstream nozzle cover 41 and the width of the downstream nozzle cover 42 increase with respect to the distance from the center CP of the polishing pad 2. As explained with reference to Figure 8, the greater the distance from the center CP of the polishing pad 2, the more likely the liquid is to splash. The wing-shaped upstream nozzle cover 41 and downstream nozzle cover 42 shown in Figures 17 and 18 can effectively prevent liquid splashing.

[0063] The cleaning of the polishing surface 2a of the polishing pad 2 by the non-contact pad cleaning device is performed after the wafer W has been polished and before the next wafer is polished. The cleaning of the polishing surface 2a of the polishing pad 2 using the two-fluid nozzle 9 (hereinafter sometimes referred to as the pad cleaning operation) may be performed before or after the dressing of the polishing surface 2a of the polishing pad 2 using the dresser 22 (hereinafter sometimes referred to as the dressing operation), or it may be performed during the dressing operation.

[0064] For example, after polishing the wafer W, a dressing operation may be performed, followed by a pad cleaning operation. In another example, after polishing the wafer W, the dressing operation and the pad cleaning operation may be performed simultaneously. In yet another example, the dressing operation may be performed while polishing the wafer W, and the pad cleaning operation may be performed after polishing and dressing the wafer W. The time for the pad cleaning operation, i.e., the cleaning time for the polishing pad 2 using the two-fluid nozzle 9, can be set arbitrarily.

[0065] Figure 19 is a top view showing yet another embodiment of the non-contact pad cleaning device. The configuration of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 1 to 4, so a redundant description will be omitted. The non-contact pad cleaning device further includes an inner surface cover cleaning device 51 for cleaning the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42. The inner surface cover cleaning device 51 includes a plurality of cleaning nozzles 52 arranged radially outward from the rotary table 5, and a cleaning fluid supply line 53 connected to these cleaning nozzles 52. The cleaning fluid supply line 53 is connected to a cleaning fluid supply source, which is not shown.

[0066] The cleaning of the upstream nozzle cover 41 and the downstream nozzle cover 42 is performed after the cleaning of the polishing surface 2a of the polishing pad 2 by the non-contact pad cleaning device is completed. Specifically, as shown in Figure 20, the nozzle oscillation mechanism 38 moves the polishing surface cleaning device 8 from a position above the polishing surface 2a to a position above the multiple cleaning nozzles 52. The multiple cleaning nozzles 52 are positioned lower than the upstream nozzle cover 41 and the downstream nozzle cover 42. A cleaning solution (e.g., pure water, or chemical solution, or a combination thereof) is supplied to the multiple cleaning nozzles 52 through a cleaning solution supply line 53. The multiple cleaning nozzles 52 are arranged along the longitudinal direction of the upstream nozzle cover 41 and the downstream nozzle cover 42. That is, some of the multiple cleaning nozzles 52 are positioned below the upstream nozzle cover 41, and the rest of the multiple cleaning nozzles 52 are positioned below the downstream nozzle cover 42.

[0067] Figure 21 shows how multiple cleaning nozzles 52 discharge cleaning fluid onto the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42. The cleaning fluid is discharged from below toward the upstream nozzle cover 41 and the downstream nozzle cover 42. The inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42 are cleaned with the cleaning fluid, and any abrasive debris and slurry adhering to the inner surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42 are washed away by the cleaning fluid.

[0068] Figure 22 is a top view showing yet another embodiment of the non-contact pad cleaning device. The configuration of this embodiment, which is not specifically described, is the same as that of the embodiment described with reference to Figures 1 to 4, so the redundant description is omitted. The non-contact pad cleaning device further includes a cover outer surface cleaning device 61 for cleaning the outer surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42. The cover outer surface cleaning device 61 includes a plurality of cleaning nozzles 62 arranged radially outward from the rotary table 5, and a cleaning fluid supply line 63 connected to these cleaning nozzles 62. The cleaning fluid supply line 63 is connected to a cleaning fluid supply source, which is not shown.

[0069] The cleaning of the upstream nozzle cover 41 and the downstream nozzle cover 42 is performed after the cleaning of the polishing surface 2a of the polishing pad 2 by the non-contact pad cleaning device is completed. Specifically, as shown in Figure 23, the nozzle oscillation mechanism 38 moves the polishing surface cleaning device 8 from a position above the polishing surface 2a to a position below the multiple cleaning nozzles 62. The multiple cleaning nozzles 62 are positioned higher than the upstream nozzle cover 41 and the downstream nozzle cover 42. A cleaning solution (e.g., pure water, or a chemical solution, or a combination thereof) is supplied to the multiple cleaning nozzles 62 through a cleaning solution supply line 63. The multiple cleaning nozzles 62 are arranged along the longitudinal direction of the upstream nozzle cover 41 and the downstream nozzle cover 42. That is, some of the multiple cleaning nozzles 62 are positioned above the upstream nozzle cover 41, and the rest of the multiple cleaning nozzles 62 are positioned above the downstream nozzle cover 42.

[0070] Figure 24 shows how multiple cleaning nozzles 62 discharge cleaning fluid onto the outer surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42. The cleaning fluid is discharged from above toward the upstream nozzle cover 41 and the downstream nozzle cover 42. The outer surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42 are cleaned with the cleaning fluid, and any abrasive debris and slurry adhering to the outer surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42 are washed away by the cleaning fluid.

[0071] In one embodiment, as shown in Figure 25, a plurality of cleaning nozzles 62 may be fixed to the nozzle carrier 35 by a nozzle holding part 65. The plurality of cleaning nozzles 62 face the outer surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42. By discharging cleaning liquid from above toward the upstream nozzle cover 41 and the downstream nozzle cover 42, the outer surfaces of the upstream nozzle cover 41 and the downstream nozzle cover 42 can be cleaned. According to this embodiment, cleaning of the upstream nozzle cover 41 and the downstream nozzle cover 42 can be performed not only after cleaning of the polishing surface 2a of the polishing pad 2 by the non-contact pad cleaning device is completed, but also while cleaning of the polishing surface 2a of the polishing pad 2 by the non-contact pad cleaning device is being performed.

[0072] The embodiments described with reference to Figures 2 to 25 can be combined as appropriate. For example, the embodiment described with reference to Figure 7 is applicable to other embodiments. The cover inner surface cleaning device 51 and / or the cover outer surface cleaning device 61 described with reference to Figures 19 to 21 may be combined with each of the embodiments described with reference to Figures 10 to 18. Furthermore, both the cover inner surface cleaning device 51 and the cover outer surface cleaning device 61 may be provided.

[0073] The embodiments described above are intended to enable persons with ordinary skill in the art to implement the present invention. Various modifications of the above embodiments can be made naturally by those skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments as well. Therefore, the present invention is not limited to the embodiments described, but is to be interpreted in the broadest sense according to the technical idea defined by the claims. [Explanation of Symbols]

[0074] W wafer 2 polishing pads 2a Polished surface 5 Rotating Table 5a Table axis 7 Polishing head 8. Polishing surface cleaning device 9. Two-fluid nozzle 9a spout 10 Slurry supply nozzles 14 Spindle 16. Polishing head oscillating arm 18 Polished Head Shaft 21 Table Rotating Motor 22 Dresser 23 Dressing Discs 23a Dressing surface 24 Dresser Shafts 25 Dresser oscillating arm 28 Spindle 30 Operation Control Unit 30a storage device 30b Processing Unit 33 Liquid supply line 34 Gas supply line 35 Nozzle Carrier 35a top side 35b,35c side 38 Nozzle oscillating mechanism 41 Upstream nozzle cover 41a Inner edge 41b Outer edge 41c bottom end 42 Downstream nozzle cover 42a Inner edge 42b Outer edge 42c bottom end 44 Holding Arm 47 Inner cover 48 Outer cover 51 Cover inner surface cleaning device 52 Cleaning nozzles 53 Cleaning fluid supply line 61 Cover exterior cleaning device 62 Cleaning Nozzles 63 Cleaning fluid supply line 65 Nozzle holding part

Claims

1. A non-contact pad cleaning device for cleaning the polishing surface of a polishing pad used to polish a workpiece without contact, A rotating table for rotating the polishing pad, A polishing surface cleaning device having a plurality of two-fluid nozzles that eject two-fluid jets toward the polishing surface of the polishing pad, The system includes liquid supply lines and gas supply lines connected to the plurality of two-fluid nozzles, The polishing surface cleaning device is The plurality of two-fluid nozzles each having a plurality of nozzles that eject a jet of the two fluids, A nozzle carrier that holds the plurality of two-fluid nozzles, The nozzle carrier is equipped with an upstream nozzle cover and a downstream nozzle cover, The plurality of nozzles are arranged at different distances from the center of the polishing pad, The upstream nozzle cover is positioned upstream of the plurality of two-fluid nozzles in the rotational direction of the polishing pad. The downstream nozzle cover is positioned downstream of the plurality of two-fluid nozzles in the rotational direction of the polishing pad. A non-contact pad cleaning device in which the distance from the polishing surface to the lower end of the upstream nozzle cover is greater than the distance from the polishing surface to the lower end of the downstream nozzle cover.

2. The non-contact pad cleaning device according to claim 1, wherein the distance from the polishing surface to the lower end of the upstream nozzle cover is within the range of 10 mm to 20 mm.

3. The non-contact pad cleaning device according to claim 1, wherein the distance from the polishing surface to the lower end of the downstream nozzle cover is within the range of 3 mm to 9 mm.

4. The non-contact pad cleaning device according to claim 1, wherein the outer end of the upstream nozzle cover and the outer end of the downstream nozzle cover are located radially outward from the outer edge of the polishing pad.

5. The non-contact pad cleaning device according to claim 1, wherein the polishing surface cleaning device further comprises an outer cover connected to the outer end of the upstream nozzle cover and the outer end of the downstream nozzle cover.

6. The non-contact pad cleaning device according to claim 1, wherein the polishing surface cleaning device further comprises an inner cover connected to the inner end of the upstream nozzle cover and the inner end of the downstream nozzle cover.

7. The non-contact pad cleaning device according to claim 1, wherein the width of the upstream nozzle cover in a direction perpendicular to the longitudinal direction of the nozzle carrier is greater than the width of the downstream nozzle cover in a direction perpendicular to the longitudinal direction of the nozzle carrier.

8. The non-contact pad cleaning device according to claim 1, wherein each of the plurality of nozzles is parallel to the longitudinal direction of the nozzle carrier.

9. The non-contact pad cleaning device according to claim 1, further comprising a nozzle oscillating mechanism for oscillating the polishing surface cleaning device above the polishing pad.

10. The system further comprises an operation control unit that controls the operation of the nozzle oscillation mechanism, The aforementioned operation control unit is configured to give a command to the nozzle oscillation mechanism to oscillate the polishing surface cleaning device above the polishing pad at a preset oscillation angle. The non-contact pad cleaning device according to claim 9, wherein the preset oscillation angle is changeable.

11. The upstream nozzle cover is inclined downward toward the upstream side in the rotational direction of the rotary table. The non-contact pad cleaning device according to claim 1, wherein the downstream nozzle cover is inclined downward toward the downstream side in the rotational direction of the rotary table.

12. The non-contact pad cleaning device according to claim 1, wherein the plurality of nozzles are inclined at different angles with respect to the longitudinal direction of the nozzle carrier.

13. The non-contact pad cleaning device according to claim 12, wherein the plurality of nozzles are each located on a plurality of straight lines passing through the center of the polishing pad when viewed from above the polishing pad.

14. The non-contact pad cleaning device according to claim 1, further comprising a cover inner surface cleaning device for cleaning the inner surfaces of the upstream nozzle cover and the downstream nozzle cover.

15. The non-contact pad cleaning device according to claim 1, further comprising a cover outer surface cleaning device for cleaning the outer surfaces of the upstream nozzle cover and the downstream nozzle cover.

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