Polishing method and polishing apparatus

Abstract

To provide polishing method capable of stabilizing a polishing process of a substrate.SOLUTION: In this polishing method, once a substrate W has been polished, a fine bubble liquid is supplied onto a polishing pad 1.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a polishing method and a polishing apparatus. [Background technology]

[0002] In the manufacturing process of semiconductor devices, technology for planarizing device surfaces is becoming increasingly important. The most important of these planarization technologies is chemical mechanical polishing (CMP). Chemical mechanical polishing (hereinafter referred to as CMP) uses a polishing device to supply a polishing liquid (slurry) containing abrasive grains such as silica (SiO2) or ceria (CeO2) to a polishing pad, while a polishing head holding a substrate such as a wafer slides against the polishing surface of the polishing pad.

[0003] After polishing a substrate, a liquid (e.g., pure water) is supplied onto the polishing pad to stabilize the substrate polishing process. For example, the substrate is water-polished to remove polishing debris and abrasive particles from the polishing liquid adhering to the surface of the substrate, or the polishing pad is dressed to condition the surface of the polishing pad and remove polishing debris and abrasive particles from the polishing liquid in preparation for polishing the next substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-44250 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the polishing pressure on the substrate is increased or the processing time is extended during water polishing of the substrate in order to stabilize the substrate polishing process, not only will substrate throughput decrease, but there is also a risk of defects occurring in the substrate.

[0006] In order to stabilize the substrate polishing process, if the dressing load is increased or the rotation speed of the polishing table is increased during polishing pad dressing, thereby removing a large amount of polishing pad material, not only will the life of the polishing pad be shortened, but the polishing rate and substrate profile may also be adversely affected.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a polishing method and a polishing apparatus that can stabilize the substrate polishing process. [Means for solving the problem]

[0008] In one aspect, a polishing method is provided in which a polishing table supporting a polishing pad is rotated, a polishing liquid is supplied onto the polishing pad, a substrate held by a polishing head is pressed against the polishing pad to polish the substrate, and after polishing of the substrate is completed, a fine bubble liquid is supplied onto the polishing pad.

[0009] In one embodiment, the fine bubble liquid is supplied onto the polishing pad from one or more nozzles of a nozzle arm that can swing in the radial direction of the polishing table. In one embodiment, the fine bubble liquid is supplied onto the polishing pad while the substrate is pressed against the polishing pad, and the substrate is polished with the fine bubble liquid. In one embodiment, the fine bubble liquid comprises an ultra-fine bubble liquid having a bubble diameter of 1 micrometer or less.

[0010] In one aspect, after polishing of the substrate is completed, the substrate is transported from the polishing pad, and after the substrate is transported, a dresser is moved onto the polishing pad to dress the polishing pad, and while the polishing pad is being dressed, the fine bubble liquid is supplied onto the polishing pad. In one embodiment, the fine bubble liquid comprises a microbubble liquid having a bubble diameter of 1 micrometer to 100 micrometers or less. In one embodiment, the fine bubble liquid is supplied onto the polishing pad from an atomizer extending in the radial direction of the polishing table.

[0011] In one aspect, after polishing of the substrate is completed, the substrate is transported from the polishing pad, and after the substrate is transported, the polishing head is moved to a retracted position located outside the polishing pad, and the fine bubble liquid is supplied to the polishing head positioned at the retracted position to clean the polishing head. In one embodiment, the fine bubble liquid contains bubbles generated from a gas corresponding to the structure of the substrate, among a plurality of types of gas. In one embodiment, the fine bubble liquid is generated by a pressurized dissolution method in which the gas is dissolved in the liquid. In one embodiment, the number of bubbles contained in the fine bubble liquid is measured using a particle counter, and the fine bubble liquid is supplied after the number of bubbles reaches a predetermined reference number.

[0012] In one aspect, a polishing apparatus is provided, which includes a polishing table that supports a polishing pad, a polishing head that presses a substrate against the polishing pad, a liquid supply mechanism that supplies liquid to the polishing pad, and a control device that controls the operation of the liquid supply mechanism. The liquid supply mechanism includes a fine bubble liquid supply device that supplies fine bubble liquid onto the polishing pad after polishing of the substrate is completed.

[0013] In one embodiment, the fine bubble liquid supply device includes a nozzle arm that can swing in the radial direction of the polishing table, and one or more fine bubble liquid nozzles arranged on the nozzle arm that supply the fine bubble liquid onto the polishing pad. In one embodiment, the fine bubble liquid supplying device supplies ultra-fine bubble liquid having a bubble diameter of 1 micrometer or less onto the polishing pad as the fine bubble liquid while the polishing head presses the substrate against the polishing pad. In one embodiment, the polishing apparatus includes a dressing device that dresses the polishing pad and is electrically connected to the control device, and after polishing of the substrate is completed and the substrate is transported, the control device operates the dressing device to move a dresser onto the polishing pad and dress the polishing pad, and the fine bubble liquid supply device supplies microbubble liquid having a bubble diameter of 1 micrometer to 100 micrometers or less onto the polishing pad as the fine bubble liquid during dressing of the polishing pad.

[0014] In one aspect, the polishing apparatus includes an atomizer extending in the radial direction of the polishing table, and the fine bubble liquid supplying device supplies the fine bubble liquid from the atomizer onto the polishing pad. In one aspect, after polishing of the substrate is completed and the substrate is transported, the control device moves the polishing head to a retracted position located outside the polishing pad, and the fine bubble liquid supply device supplies the fine bubble liquid to the polishing head positioned at the retracted position to clean the polishing head. In one embodiment, the fine bubble liquid contains bubbles generated from a gas corresponding to the structure of the substrate, among a plurality of types of gas.

[0015] In one aspect, the fine bubble liquid supply device includes a fine bubble liquid generator that generates the fine bubble liquid by a pressurized dissolution method in which the gas is dissolved in the liquid. In one embodiment, the fine bubble liquid supplying device is equipped with a particle counter that measures the number of bubbles contained in the fine bubble liquid, and the fine bubble liquid supplying device supplies the fine bubble liquid after the number of bubbles measured by the particle counter reaches a predetermined reference number. [Effects of the Invention]

[0016] After polishing of the substrate is completed, a fine bubble liquid with high cleaning power is supplied onto the polishing pad, thereby stabilizing the substrate polishing process. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 illustrates an embodiment of a polishing apparatus. [Figure 2] FIG. 2 is a diagram showing a liquid supply mechanism. [Figure 3] FIG. 1 is a diagram showing a fine bubble liquid generating device. [Figure 4] FIG. 10 is a diagram showing another embodiment of the fine bubble liquid supply device. [Figure 5] FIG. 10 is a diagram showing another embodiment of the fine bubble liquid generating device. [Figure 6] FIG. 10 is a diagram showing a processing flow of a substrate by a control device. [Figure 7] FIG. 10 is a diagram showing another embodiment of the polishing apparatus. [Figure 8] FIG. 10 is a diagram showing another embodiment of the substrate processing flow by the control device. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are designated by the same reference numerals, and redundant description will be omitted.

[0019] Fig. 1 is a diagram showing one embodiment of a polishing apparatus. As shown in Fig. 1, the polishing apparatus PA includes a polishing table 2 that supports a polishing pad 1, a polishing head 3 that presses a substrate W such as a wafer against the polishing pad 1, and a liquid supply mechanism 4 that supplies a liquid to the polishing pad 1. The liquid supplied from the liquid supply mechanism 4 onto the polishing pad 1 is a polishing liquid (slurry), deionized water (DIW), or a fine bubble liquid (described later).

[0020] The polishing table 2 is connected to a table motor (not shown) that rotates the polishing table 2 via a table shaft (not shown) that supports the polishing table 2. The polishing pad 1 is attached to the upper surface of the polishing table 2, and the upper surface of the polishing pad 1 forms a polishing surface that polishes the substrate W.

[0021] The polishing head 3 is fixed to the lower end of a polishing head shaft (not shown). The polishing head 3 is configured to hold the substrate W on its lower surface by vacuum suction. The polishing head shaft is connected to a rotation mechanism (not shown), and the polishing head 3 is rotated via the polishing head shaft by this rotation mechanism.

[0022] The polishing apparatus PA further includes a dressing device 10 for dressing the polishing pad 1. The dressing device 10 includes a dresser 15 that is in sliding contact with the polishing surface of the polishing pad 1, a dresser arm 11 that supports the dresser 15, and a dresser pivot shaft 12 that pivots the dresser arm 11. The dresser pivot shaft 12 is disposed outside the polishing pad 1.

[0023] As the dresser arm 11 rotates, the dresser 15 oscillates over the polishing surface. The underside of the dresser 15 forms a dressing surface made of a large number of abrasive grains such as diamond particles. The dresser 15 rotates while oscillating over the polishing surface, dressing the polishing surface by slightly scraping away the polishing pad 1.

[0024] The polishing apparatus PA further includes an atomizer 20 that sprays a cleaning liquid (more specifically, a fine bubble liquid, which will be described later) onto the polishing surface of the polishing pad 1 to clean the polishing surface. The atomizer 20 extends along the radial direction of the polishing pad 1 (or the polishing table 2) and is located above the polishing surface of the polishing pad 1. The atomizer 20 sprays a large flow of cleaning liquid onto the polishing surface, thereby removing polishing debris and abrasive grains contained in the polishing liquid from the polishing surface of the polishing pad 1. The atomizer 20 sprays a large flow of cleaning liquid onto the polishing surface even when the polishing surface is being dressed by the dresser 15.

[0025] The polishing apparatus PA includes a control device 9 that controls the operation of its components (e.g., the polishing table 2, the polishing head 3, the liquid supply mechanism 4, the dressing device 10, and the atomizer 20). The components of the polishing apparatus PA are electrically connected to the control device 9. Thus, the control device 9 can control the operation of the components of the polishing apparatus PA.

[0026] 2 is a diagram showing the liquid supply mechanism 4. As shown in Fig. 2, the liquid supply mechanism 4 includes a nozzle arm 30 that is movable in the radial direction of the polishing table 2, a slurry nozzle 31 disposed at a tip portion 30a of the nozzle arm 30, and a pure water nozzle 32 and fine bubble liquid nozzles 33A, 33B, 33C, 33D, and 33E disposed at an arm portion 30b of the nozzle arm 30.

[0027] The nozzle arm 30 is connected to a nozzle pivot shaft 35 that rotates the nozzle arm 30 (see FIG. 1). The nozzle pivot shaft 35 is disposed outside the polishing pad 1. The nozzle arm 30 is configured to be movable between a retracted position outside the polishing pad 1 and a processing position above the polishing pad 1 by driving the nozzle pivot shaft 35 (more specifically, by a motor connected to the nozzle pivot shaft 35).

[0028] 2, when the nozzle arm 30 is in the processing position, the tip portion 30a of the nozzle arm 30 is positioned above the center CL of the polishing pad 1. Therefore, the slurry nozzle 31 disposed at the tip portion 30a of the nozzle arm 30 is positioned above the center CL of the polishing pad 1 so that its ejection port faces the center CL of the polishing pad 1.

[0029] When the nozzle arm 30 is in the processing position, each of the fine bubble liquid nozzles 33A to 33E is positioned above the region between the center CL of the polishing pad 1 and the outer periphery of the polishing pad 1 so that its jetting port faces this region. The pure water nozzle 32 is positioned adjacent to the slurry nozzle 31, and the fine bubble liquid nozzle 33A is positioned adjacent to the pure water nozzle 32.

[0030] The fine bubble liquid nozzles 33A to 33E are arranged in this order from the tip end (i.e., tip portion 30a) to the base end of the nozzle arm 30. Each of the fine bubble liquid nozzles 33A to 33E may have a single-tube shape or a spray nozzle shape.

[0031] 2, the liquid supply mechanism 4 is equipped with multiple (more specifically, five) fine bubble liquid nozzles, but the number of fine bubble liquid nozzles is not limited to this embodiment. In one embodiment, the liquid supply mechanism 4 may be equipped with one fine bubble liquid nozzle, or may be equipped with two or more fine bubble liquid nozzles.

[0032] The liquid supply mechanism 4 includes a slurry line 42 connected to the slurry nozzle 31, an on-off valve 43 that opens and closes the slurry line 42, and a slurry supply source 41 that supplies the slurry to the slurry nozzle 31 through the slurry line 42. Similarly, the liquid supply mechanism 4 includes a pure water line 45 connected to the pure water nozzle 32, an on-off valve 46 that opens and closes the pure water line 45, and a pure water supply source 44 that supplies pure water to the pure water nozzle 32 through the pure water line 45.

[0033] The on-off valves 43 and 46 are electrically connected to the control device 9. When the control device 9 opens the on-off valve 43, the slurry is supplied from the slurry supply source 41 to the slurry nozzle 31 through the slurry line 42. Similarly, when the control device 9 opens the on-off valve 46, the pure water is supplied from the pure water supply source 44 to the pure water nozzle 32 through the pure water line 45.

[0034] 2, the liquid supply mechanism 4 includes a fine bubble liquid supply device 50 that supplies fine bubble liquid to each of the fine bubble liquid nozzles 33A to 33E. The fine bubble liquid supply device 50 includes a fine bubble liquid supply line 52 connected to the fine bubble liquid nozzle 33A, an injection nozzle 51 connected to the fine bubble liquid supply line 52, and a fine bubble liquid return line 53 connected to the fine bubble liquid supply line 52 and each of the fine bubble liquid nozzles 33B to 33E.

[0035] The fine bubble liquid supply device 50 includes a bypass line 57 connected to the fine bubble liquid supply line 52, a microbubble filter 59 connected to the fine bubble liquid supply line 52, and an ultrafine bubble filter 58 connected to the bypass line 57.

[0036] The fine bubble liquid supply device 50 is equipped with three-way valves 56A and 56B that connect the bypass line 57 to the fine bubble liquid supply line 52. Each of the three-way valves 56A and 56B is electrically connected to the control device 9. By operating each of the three-way valves 56A and 56B, the control device 9 can switch the flow of the liquid (more specifically, the mixed liquid described below) sprayed from the spray nozzle 51 between a flow that passes through a microbubble filter 59 and a flow that passes through an ultrafine bubble filter 58.

[0037] The microbubble filter 59 allows microbubble liquid with a bubble diameter of 1 micrometer to 100 micrometers or less to pass through, and captures (removes) bubbles larger than microbubbles. Therefore, when the liquid injected from the injection nozzle 51 passes through the microbubble filter 59, microbubble liquid with a bubble diameter of 1 micrometer to 100 micrometers or less is supplied.

[0038] The ultra-fine bubble filter 58 allows ultra-fine bubble liquid with a bubble diameter of 1 micrometer or less to pass through, and captures (removes) bubbles larger than ultra-fine bubbles. Therefore, when the liquid sprayed from the spray nozzle 51 passes through the ultra-fine bubble filter 58, ultra-fine bubble liquid with a bubble diameter of 1 micrometer or less is supplied.

[0039] In this way, the fine bubble liquid supplying device 50 can supply both microbubble liquid and ultrafine bubble liquid. In this specification, fine bubble liquid is a general concept that encompasses microbubble liquid and ultrafine bubble liquid, and ultrafine bubble liquid has smaller bubble diameters than microbubble liquid.

[0040] Fine bubbles have the property of floating in water for a long time and have a large specific surface area.Fine bubbles are also hydrophobic and lipophilic.Fine bubble liquids containing such fine bubbles promote chemical reactions at interfaces and have the property of easily adsorbing to the surfaces of hydrophobic substances such as oils and fats.

[0041] The fine bubble liquid supplying device 50 may further include a particle counter 60 located downstream of the three-way valve 56A in the flow direction of the fine bubble liquid. The particle counter 60 is configured to measure the number of bubbles contained in the fine bubble liquid. Therefore, the fine bubble liquid supplying device 50 may supply the fine bubble liquid from each of the fine bubble liquid nozzles 33A to 33E after the number of bubbles contained in the fine bubble liquid reaches a predetermined reference number based on the number of bubbles measured by the particle counter 60. Fine bubble liquid containing bubbles that meet the predetermined reference number can fully exhibit its properties.

[0042] As shown in Fig. 2, the ultra-fine bubble filter 58 and the microbubble filter 59 are disposed adjacent to the nozzle arm 30 (more specifically, the fine bubble liquid nozzles 33A to 33E). If the distance between the filters 58, 59 and the fine bubble liquid nozzles 33A to 33E is large, there is a risk that the bubbles contained in the fine bubble liquid will disappear as the fine bubble liquid moves to the fine bubble liquid nozzles 33A to 33E. In this embodiment, this arrangement reliably prevents the bubbles contained in the fine bubble liquid from disappearing.

[0043] The fine bubble liquid return line 53 is equipped with branch lines 53A, 53B, 53C, 53D, and 53E connected to the fine bubble liquid nozzles 33A to 33E. The fine bubble liquid supply device 50 is equipped with on-off valves 54A, 54B, 54C, 54D, and 54E connected to the branch lines 53A, 53B, 53C, 53D, and 53E, and an on-off valve 55 connected to the fine bubble liquid return line 53. The on-off valves 54A, 54B, 54C, 54D, and 54E and the on-off valve 55 are electrically connected to a control device 9. The control device 9 can control the operation of each of the on-off valves 54A, 54B, 54C, 54D, and 54E, as well as the operation of the on-off valve 55.

[0044] When supplying fine bubble liquid from the fine bubble liquid nozzles 33A to 33E, the control device 9 opens the on-off valves 54A to 54E and closes the on-off valve 55. By this operation, the fine bubble liquid flowing through the fine bubble liquid supply line 52 is supplied from the fine bubble liquid nozzles 33A to 33E.

[0045] The on-off valves 54A to 54E correspond to the fine bubble liquid nozzles 33A to 33E. Therefore, by controlling each of the on-off valves 54A to 54E, the control device 9 can arbitrarily select the fine bubble liquid nozzle 33A to 33E to which the fine bubble liquid should be supplied.

[0046] For example, the control device 9 opens the on-off valve 54A and closes the on-off valves 54B, 54C, 54D, 54E and the on-off valve 55, so that the fine bubble liquid is supplied only from the fine bubble liquid nozzle 33A. The control device 9 opens the on-off valve 55 and closes the on-off valves 54A, 54B, 54C, 54D, 54E, so that the fine bubble liquid is not supplied from any of the fine bubble liquid nozzles 33A to 33E and is discharged to the outside through the fine bubble liquid return line 53.

[0047] Fig. 3 is a diagram showing a fine bubble liquid generating device. As shown in Fig. 3, a fine bubble liquid supplying device 50 is equipped with a fine bubble liquid generating device 100 that generates fine bubble liquid. The fine bubble liquid generating device 100 is a device that generates fine bubble liquid by a pressurized dissolution method in which gas is dissolved in liquid.

[0048] As shown in Fig. 3, the fine bubble liquid generator 100 includes a buffer tank 61 for storing a mixture of pure water and gas, a pure water supply line 62 for supplying pure water to the buffer tank 61, and a gas supply line 63 for supplying gas (nitrogen gas as an inert gas in the embodiment shown in Fig. 3) to the buffer tank 61. The fine bubble liquid generator 100 also includes a transfer line 65 connected to the buffer tank 61, a pump 66 connected to the transfer line 65, and a pressurized dissolution tank 64 for storing the mixture transferred by driving the pump 66.

[0049] The control device 9 is electrically connected to the pump 66 and can drive the pump 66. By driving the pump 66, the mixed liquid in the buffer tank 61 is transferred to the pressurized dissolving tank 64 through the transfer line 65. The mixed liquid is stored in the pressurized dissolving tank 64 in a pressurized state. The fine bubble liquid generator 100 is equipped with an introduction line 67 that introduces the pressurized mixed liquid in the pressurized dissolving tank 64 into the spray nozzle 51, and an on-off valve 68 connected to the introduction line 67. The on-off valve 68 is connected to the control device 9, and when the control device 9 opens the on-off valve 68, the pressurized mixed liquid is introduced into the spray nozzle 51 through the introduction line 67.

[0050] The injection nozzle 51 is equipped with a pressure reduction / release section (not shown) that generates a high pressure loss inside. The pressure reduction / release section is, for example, an orifice. When the pressurized mixed liquid in which the gas is sufficiently dissolved is introduced into the injection nozzle 51, the pressure of the mixed liquid is suddenly reduced by the pressure reduction / release section, and the dissolved gas is generated in the mixed liquid as fine bubbles. The fine bubbles contained in the mixed liquid injected from the injection nozzle 51 are sorted into microbubbles or ultrafine bubbles by a microbubble filter 59 or an ultrafine bubble filter 58.

[0051] 4 is a diagram showing another embodiment of the fine bubble liquid supply device. As described above, the liquid supply mechanism 4 (more specifically, the fine bubble liquid supply device 50) may include one fine bubble liquid nozzle 33 and an on-off valve 54 corresponding to the fine bubble liquid nozzle 33.

[0052] 4, the fine bubble liquid supplying device 50 does not necessarily have to include both the ultra-fine bubble filter 58 and the microbubble filter 59, but may include either the ultra-fine bubble filter 58 or the microbubble filter 59. Furthermore, the fine bubble liquid supplying device 50 does not necessarily have to include the particle counter 60.

[0053] Fig. 5 is a diagram showing another embodiment of the fine bubble liquid generator. As shown in Fig. 5, the fine bubble liquid generator 100 may include a gas supply line 63A for supplying a first gas (e.g., nitrogen gas) to a buffer tank 61, and a gas supply line 63B for supplying a second gas (e.g., oxygen gas, carbon dioxide gas (carbon dioxide gas), or ozone gas) to the buffer tank 61.

[0054] There are gas species that can be used depending on the structure of the substrate W to be processed. Therefore, the fine bubble liquid generating device 100 selectively supplies a gas that corresponds to the structure of the substrate W to be processed from the gas supply lines 63A, 63B. With this configuration, the fine bubble liquid supplying device 50 can supply fine bubble liquid having bubbles generated from a gas that corresponds to the structure of the substrate W, out of multiple types of gas.

[0055] 6 is a diagram showing a substrate processing flow by the control device. The control device 9 operates the nozzle arm 30 to position the tip portion 30a of the nozzle arm 30 above the center CL of the polishing pad 1. The control device 9 opens the on-off valve 43 while rotating the polishing table 2, and supplies slurry onto the polishing pad 1 (see step S101 in FIG. 6). In this state, the control device 9 rotates the substrate W held by the polishing head 3 and presses it against the polishing pad 1 to perform slurry polishing of the substrate W (see step S102). In step S102, the control device 9 rotates the polishing pad 1 and the polishing head 3 in the same direction to polish the substrate W.

[0056] At this time, the control device 9 performs supply preparations for a stable supply of ultra-fine bubble liquid in parallel with the operation of polishing the substrate W (i.e., step S102) (see step S103). More specifically, in order to supply the ultra-fine bubble liquid, the control device 9 operates the three-way valves 56A and 56B to open the bypass line 57. Then, the liquid sprayed from the spray nozzle 51 passes through the ultra-fine bubble filter 58 without passing through the microbubble filter 59, and as a result, the fine bubble liquid supply device 50 supplies the ultra-fine bubble liquid.

[0057] The control device 9 closes the on-off valves 54A to 54E and opens the on-off valve 55, so that the ultra-fine bubble liquid is not supplied from the fine bubble liquid nozzles 33A to 33E but is discharged to the outside through the fine bubble liquid return line 53. Based on the number of bubbles measured by the particle counter 60, the control device 9 determines whether the number of bubbles in the ultra-fine bubble liquid is stable.

[0058] Thereafter, the control device 9 closes the on-off valve 43 to terminate the slurry polishing of the substrate W. After the slurry polishing of the substrate W is terminated, the control device 9 starts water polishing (fine bubble liquid polishing in this embodiment) of the substrate W (see step S104). More specifically, the control device 9 opens at least one of the on-off valves 54A to 54E and closes the on-off valve 55 to supply ultra-fine bubble liquid onto the polishing pad 1 from at least one of the fine bubble liquid nozzles 33A to 33E.

[0059] When the ultra-fine bubble liquid is supplied onto the polishing pad 1, the bubbles contained in the ultra-fine bubble liquid burst. The impact of the bursting bubbles locally releases energy (light emission, high temperature and pressure, shock waves, etc.), which removes polishing debris and abrasive grains from the polishing liquid that have adhered to the surface of the substrate W. In addition, because the gas-liquid interface of the ultra-fine bubble liquid takes on a negative potential, the ultra-fine bubble liquid adsorbs and removes positively charged electrolyte ions and dirt.

[0060] The magnitude of the bubble impact depends on the bubble diameter. Therefore, when the fine bubble liquid supplied to the polishing pad 1 is a microbubble liquid, the impact caused by the bursting of bubbles contained in the microbubble liquid is greater than the impact caused by the bursting of bubbles contained in the ultrafine bubble liquid.

[0061] In this embodiment, the substrate W is polished with ultra-fine bubble liquid. Therefore, the impact on the substrate W caused by the bursting of bubbles is small. Since the substrate W may have a fine structure, polishing the substrate W with ultra-fine bubble liquid can reduce damage to the substrate W. As a result, defects can be prevented from occurring in the substrate W. Furthermore, with this configuration, it is not necessary to extend the processing time of the substrate W, and the throughput of the substrate W can be improved.

[0062] After completing the ultra-fine bubble liquid polishing of the substrate W, the control device 9 closes the on-off valves 54A to 54E and opens the on-off valve 46 to supply pure water onto the polishing pad 1. Thereafter, the control device 9 rotates the polishing table 2 and the polishing head 3 to adsorb the substrate W onto the polishing head 3 (see step S105). In this state, the control device 9 raises the polishing head 3 to position the polishing head 3 above the polishing pad 1.

[0063] The control device 9 performs supply preparation for a stable supply of microbubble liquid (see step S106) in parallel with the substrate W transport operation (i.e., step S105 and step S107 described later). More specifically, in order to supply the microbubble liquid, the control device 9 operates the three-way valves 56A and 56B to close the bypass line 57 and open part of the fine bubble liquid supply line 52 (more specifically, the upstream side of the three-way valve 56A and the downstream side of the three-way valve 56B). Then, the fine bubble liquid passes through the microbubble filter 59, and as a result, the fine bubble liquid supply device 50 supplies the microbubble liquid.

[0064] When the control device 9 closes the on-off valves 54A to 54E and opens the on-off valve 55, the microbubble liquid is not supplied from the fine bubble liquid nozzles 33A to 33E but is discharged to the outside through the fine bubble liquid return line 53. Based on the number of bubbles measured by the particle counter 60, the control device 9 determines whether the number of bubbles in the microbubble liquid is stable.

[0065] After step S105, the control device 9 moves the polishing head 3 holding the substrate W to the outside of the polishing pad 1, and transports the substrate W to the next process (see step S107). After step S107, the control device 9 moves the dresser 15 above the polishing pad 1 while supplying a microbubble liquid onto the polishing pad 1 to dress the polishing pad 1 (see step S108).

[0066] When dressing the polishing pad 1, the control device 9 may inject a large flow rate of cleaning liquid onto the surface of the polishing pad 1 from the atomizer 20 disposed above the polishing pad 1. In one embodiment, the flow rate of the fine bubble liquid supplied from the nozzle arm 30 is 1 L / min, and the flow rate of the fine bubble liquid supplied from the atomizer 20 is 10 L / min.

[0067] In this embodiment, the fine bubble liquid supplying device 50 is configured to supply fine bubble liquid through the nozzle arm 30. In one embodiment, the fine bubble liquid supplying device 50 may be configured to supply fine bubble liquid through the atomizer 20. With this configuration, the fine bubble liquid supplying device 50 can not only supply fine bubble liquid through the nozzle arm 30, but also supply a large flow rate of fine bubble liquid onto the polishing pad 1 through the atomizer 20. The structure for supplying fine bubble liquid from the atomizer 20 is the same as the structure for supplying fine bubble liquid from the nozzle arm 30, so a description thereof will be omitted.

[0068] During the dressing of the polishing pad 1, the fine bubble liquid supply device 50 supplies the microbubble liquid onto the polishing pad 1. More specifically, the control device 9 opens at least one of the on-off valves 54A to 54E and closes the on-off valve 55 to supply the microbubble liquid onto the polishing pad 1 from at least one of the fine bubble liquid nozzles 33A to 33E.

[0069] As described above, the impact caused by the bursting of bubbles contained in microbubble liquid is greater than the impact caused by the bursting of bubbles contained in ultrafine bubble liquid. Therefore, the fine bubble liquid supply device 50 can apply a large impact to the surface (polishing surface) of the polishing pad 1 due to the bursting of bubbles.

[0070] This configuration can more reliably eliminate clogging of the polishing pad 1. Therefore, the amount of polishing pad 1 that is scraped off during dressing of the polishing pad 1 can be reduced. As a result, the life of the polishing pad 1 can be extended, and there is no adverse effect on the polishing rate or the profile of the substrate W. Furthermore, the dressing time can be shortened, improving throughput.

[0071] According to this embodiment, the fine bubble liquid supplying device 50 can stabilize the polishing process of the substrate W by supplying fine bubble liquid (i.e., ultra-fine bubble liquid, microbubble liquid) having high cleaning power onto the polishing pad 1 after polishing of the substrate W is completed.

[0072] Fig. 7 is a diagram showing another embodiment of the polishing apparatus. As shown in Fig. 7, the polishing apparatus PA (more specifically, the fine bubble liquid supply device 50) may include a fine bubble liquid distributor 70 that distributes fine bubble liquid to the components of the polishing apparatus PA (in this embodiment, the polishing head 3, the liquid supply mechanism 4, and the dressing device 10).

[0073] The fine bubble liquid distributor 70 includes a distribution line 71A connected to the fine bubble liquid return line 53, a cleaning nozzle 72A connected to the distribution line 71A, and an on-off valve 73A connected to the distribution line 71A.

[0074] The cleaning nozzle 72A is positioned adjacent to the polishing head 3, which is placed in the retracted position, and the fine bubble liquid supply device 50 sprays fine bubble liquid from below the polishing head 3 toward the polishing head 3. By spraying fine bubble liquid with high cleaning power, the polishing head 3 can be cleaned more effectively.

[0075] 6, after transporting the substrate W, the control device 9 moves the polishing head 3 to a retracted position located outside the polishing pad 1, and supplies fine bubble liquid to the polishing head 3 positioned at the retracted position to clean the polishing head 3. The fine bubble liquid supply device 50 cleans the polishing head 3 while the polishing head 3 is positioned at the retracted position, thereby preventing the fine bubble liquid used to clean the polishing head 3 from dropping onto the polishing pad 1.

[0076] The on-off valve 73A is electrically connected to the control device 9. The control device 9 closes the on-off valves 54A to 54E, while opening the on-off valve 55 (see FIG. 2) and the on-off valve 73A to supply the fine bubble liquid to the polishing head 3. In step S108, the fine bubble liquid supplying device 50 supplies the microbubble liquid, and therefore, in step S109, the fine bubble liquid supplying device 50 also supplies the microbubble liquid to the polishing head 3.

[0077] As shown in FIG. 7, the fine bubble liquid distributor 70 may include a distribution line 71B connected to the fine bubble liquid return line 53, and cleaning nozzles 72B and 72D connected to the distribution line 71B.

[0078] The cleaning nozzle 72B is disposed adjacent to the nozzle arm 30, which is disposed at the retracted position. A branch line 71Ba branching from the distribution line 71B is connected to the cleaning nozzle 72B, and an on-off valve 73B is connected to the branch line 71Ba.

[0079] The cleaning nozzle 72D is disposed adjacent to the dresser 15, which is disposed at the retracted position. An on-off valve 73D connected to the distribution line 71B is disposed adjacent to the cleaning nozzle 72D.

[0080] The control device 9 can close the on-off valves 54A to 54E and open the on-off valve 55 and the on-off valves 73B and 73D to supply the fine bubble liquid to the nozzle arm 30 and the dresser 15. For example, in step S109 of FIG. 6, the control device 9 may clean not only the polishing head 3 but also at least one of the nozzle arm 30 and the dresser 15.

[0081] Fig. 8 is a diagram showing another embodiment of the substrate processing flow by the control device. As shown in Fig. 8, the control device 9 supplies slurry onto the polishing pad 1 and performs slurry polishing on the substrate W (see steps S201 and S202). The control device 9 may perform supply preparation for a stable supply of ultra-fine bubble liquid in parallel with the polishing operation of the substrate W (i.e., step S202) (see step S203), and supply the ultra-fine bubble liquid to the dresser 15 through the fine bubble liquid distributor 70 (see step S204). In one embodiment, the control device 9 may clean not only the dresser 15 but also the atomizer 20.

[0082] Thereafter, the control device 9 starts fine bubble liquid polishing of the substrate W (see step S205), and after step S205 is completed, the control device 9 causes the substrate W to be adsorbed onto the polishing head 3 (see step S206).

[0083] As shown in step S207, the control device 9 performs supply preparations for a stable supply of microbubble liquid in parallel with the transport operation of the substrate W (i.e., step S206 and step S208 described later), and after transporting the substrate W to the next process (see step S208), supplies microbubble liquid onto the polishing pad 1 to dress the polishing pad 1 (see step S209).

[0084] After the substrate W is transported, the control device 9 supplies the microbubble liquid to the polishing head 3 arranged at the retracted position to clean the polishing head 3 (see step S210). In the embodiment shown in Fig. 8, the fine bubble liquid supply device 50 cleans the dresser 15 in step S204, so there is no need to clean the dresser 15 in step S210.

[0085] In the above-described embodiment, the fine bubble liquid discharged to the outside through the fine bubble liquid return line 53 is supplied to the components of the polishing apparatus PA, but the fine bubble liquid supplying device 50 may also be provided with a storage tank (not shown) for storing the fine bubble liquid discharged to the outside. The fine bubble liquid supplying device 50 may also reuse the fine bubble liquid stored in the storage tank.

[0086] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would naturally be possible for a person skilled in the art, and the technical concept of the present invention may also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but should be accorded the broadest scope consistent with the technical concept defined by the claims. [Explanation of symbols]

[0087] 1 scouring pad 2 Polishing table 3 Polishing Heads 4 Liquid supply mechanism 9 Control Device 10 Dressing device 11 Dresser arm 12 Dresser rotation axis 15 Dresser 20 Atomizer 30 nozzle arm 30a Tip part 30b Arm part 31 Slurry nozzle 32 Pure water nozzle 33A~33E Fine bubble liquid nozzle 35 Nozzle rotation axis 41 Slurry supply source 42 Slurry Line 43 On-off valve 44 Pure water source 45 Pure water line 46 On-off valve 50 Fine bubble liquid supply device 51 Injection nozzle 52 Fine bubble liquid supply line 53 Fine bubble liquid return line 53A~53E Branch Line 54A~54E On-off valve 55 On-off valve 56A, 56B three-way valve 57 Bypass Line 58 Ultra Fine Bubble Filter 59 Microbubble filter 61 Buffer Tank 62 Pure water supply line 63, 63A, 63B Gas supply lines 64 Pressurized dissolving tank 65 Transfer Line 66 Pump 67 Introduction Line 68 On-off valve 70 Fine bubble liquid distributor 71A, 71B distribution line 71Ba branch line 72A, 72B, 72D cleaning nozzle 73A, 73B, 73D On-off valves 100 Fine bubble liquid generator PA polishing equipment

Claims

1. Rotating a polishing table supporting the polishing pad; With a polishing liquid supplied onto the polishing pad, the substrate held by a polishing head is pressed against the polishing pad to polish the substrate; After polishing of the substrate is completed, fine bubble liquid is supplied onto the polishing pad through either a fine bubble liquid supply line or a bypass line connected by a three-way valve; a microbubble filter is connected to one of the fine bubble liquid supply line and the bypass line; an ultra-fine bubble filter is connected to the other of the fine bubble liquid supply line and the bypass line; supplying a first fine bubble liquid as the fine bubble liquid onto the polishing pad while pressing the substrate against the polishing pad, thereby polishing the substrate with the first fine bubble liquid; the first fine bubble liquid passing through the ultra-fine bubble filter comprises an ultra-fine bubble liquid having a bubble diameter of 1 micrometer or less; After polishing of the substrate is completed, the substrate is removed from the polishing pad; After the substrate is transferred, a dresser is moved onto the polishing pad to dress the polishing pad; supplying a second fine bubble liquid different from the first fine bubble liquid onto the polishing pad during dressing of the polishing pad; The polishing method, wherein the second fine bubble liquid passing through the microbubble filter comprises a microbubble liquid having a bubble diameter of 1 micrometer to 100 micrometers or less.

2. 2. The polishing method according to claim 1, wherein the fine bubble liquid is supplied onto the polishing pad from one or more nozzles of a nozzle arm that is swingable in the radial direction of the polishing table.

3. 3. The polishing method according to claim 1, wherein the fine bubble liquid is supplied onto the polishing pad from an atomizer extending in a radial direction of the polishing table.

4. After polishing of the substrate is completed, the substrate is removed from the polishing pad; After the substrate is transported, the polishing head is moved to a retracted position located outside the polishing pad; 4. The polishing method according to claim 1, wherein the fine bubble liquid is supplied to the polishing head disposed at the retracted position to clean the polishing head.

5. The fine bubble liquid contains bubbles generated from at least one gas selected from an inert gas and a reactive gas, 5. The polishing method according to claim 1, wherein the inert gas corresponds to nitrogen gas, and the reactive gas corresponds to oxygen gas, carbon dioxide gas, or ozone gas.

6. The polishing method according to claim 5 , wherein the fine bubble liquid is generated by a pressure dissolution method in which the gas is dissolved in the liquid.

7. Counting the number of bubbles contained in the fine bubble liquid using a particle counter; 7. The polishing method according to claim 1, wherein the fine bubble liquid is supplied after the number of bubbles reaches a predetermined reference number.

8. a polishing table supporting a polishing pad; a polishing head that presses the substrate against the polishing pad; a liquid supply mechanism for supplying a liquid to the polishing pad; a control device for controlling the operation of the liquid supply mechanism, the liquid supply mechanism includes a fine bubble liquid supply device that supplies fine bubble liquid onto the polishing pad after polishing of the substrate is completed; The fine bubble liquid supply device is a fine bubble liquid supply line for supplying the fine bubble liquid; a bypass line connected to the fine bubble liquid supply line; a three-way valve connecting the bypass line to the fine bubble liquid supply line; a microbubble filter connected to one of the fine bubble liquid supply line and the bypass line, and allowing microbubble liquid having a bubble diameter of 1 micrometer to 100 micrometers to pass through; an ultra-fine bubble filter connected to the other of the fine bubble liquid supply line and the bypass line, and allowing ultra-fine bubble liquid having a bubble diameter of 1 micrometer or less to pass through.

9. The fine bubble liquid supply device is a nozzle arm that can swing in the radial direction of the polishing table; 9. The polishing apparatus according to claim 8, further comprising: one or more fine bubble liquid nozzles arranged on the nozzle arm for supplying the fine bubble liquid onto the polishing pad.

10. 10. The polishing apparatus according to claim 8, wherein the fine bubble liquid supplying device supplies, as the fine bubble liquid, ultra-fine bubble liquid having a bubble diameter of 1 micrometer or less onto the polishing pad while the polishing head presses the substrate against the polishing pad.

11. the polishing apparatus includes a dressing device that dresses the polishing pad and is electrically connected to the control device; the control device, after polishing of the substrate is completed and the substrate is transported, operates the dressing device to move a dresser onto the polishing pad and dress the polishing pad; The polishing apparatus according to any one of claims 8 to 10, wherein the fine bubble liquid supplying device supplies, onto the polishing pad during dressing of the polishing pad, a microbubble liquid having a bubble diameter of 1 micrometer to 100 micrometers.

12. the polishing apparatus includes an atomizer extending in a radial direction of the polishing table; The polishing apparatus according to any one of claims 8 to 11, wherein the fine bubble liquid supplying device supplies the fine bubble liquid from the atomizer onto the polishing pad.

13. the control device moves the polishing head to a retracted position located outside the polishing pad after polishing of the substrate is completed and the substrate is transported; The polishing apparatus according to any one of claims 8 to 12, wherein the fine bubble liquid supplying device supplies the fine bubble liquid to the polishing head disposed at the retracted position to clean the polishing head.

14. The fine bubble liquid contains bubbles generated from at least one gas selected from an inert gas and a reactive gas, 14. The polishing apparatus according to claim 8, wherein the inert gas corresponds to nitrogen gas, and the reactive gas corresponds to oxygen gas, carbon dioxide gas, or ozone gas.

15. 15. The polishing apparatus according to claim 14, wherein the fine bubble liquid supplying device includes a fine bubble liquid generating device that generates the fine bubble liquid by a pressurized dissolution method in which the gas is dissolved in the liquid.

16. the fine bubble liquid supply device is equipped with a particle counter that measures the number of bubbles contained in the fine bubble liquid, The polishing apparatus according to any one of claims 8 to 15, wherein the fine bubble liquid supplying device supplies the fine bubble liquid after the number of bubbles measured by the particle counter reaches a predetermined reference number.

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