Polishing device and polishing method

Abstract

The present invention suitably removes, in water polishing after polishing using a polishing liquid, the polishing liquid or polishing debris.　This polishing device comprises a water supply mechanism configured to supply water to a supply position located in a central region of a polishing surface of a polishing pad. The polishing device, after performing a first polishing of polishing an object to be polished by pressing the object to be polished against the polishing pad while supplying a polishing liquid from a polishing liquid supply mechanism, stops the supply of the polishing liquid, and performs a second polishing of pressing the object to be polished against the polishing pad while supplying water from the water supply mechanism to the supply position at a flow rate of 5 L / min to 15 L / min.

Description

Polishing Device and Polishing Method

[0001] The present invention relates to a polishing device and a polishing method.

[0002] In the manufacturing process of semiconductor devices, the planarization technology of the semiconductor device surface has become increasingly important. As a planarization technology, chemical mechanical polishing (CMP (Chemical Mechanical Polishing)) is known. This chemical mechanical polishing uses a polishing device to supply a polishing liquid (slurry) containing abrasive grains such as silica (SiO2) and ceria (CeO2) to a polishing pad while bringing a substrate such as a semiconductor wafer into sliding contact with the polishing pad to perform polishing.

[0003] A polishing device for performing a CMP process includes a polishing table that supports a polishing pad and a substrate holding portion, such as a top ring or ring or a polishing head, for holding a substrate. This polishing device supplies a polishing liquid from a polishing liquid supply nozzle to the polishing pad and presses the substrate against the surface (polishing surface) of the polishing pad with a predetermined pressure. At this time, by rotating the polishing table and the substrate holding mechanism, the substrate comes into sliding contact with the polishing surface, and the surface of the substrate is polished to be flat and mirror-like.

[0004] In the device described in Patent Document 1, after polishing a substrate using a polishing liquid, water is supplied to the polishing pad to perform water polishing on the substrate. This water polishing is not aimed at substantially polishing the substrate, but at removing the slurry and polishing debris from the polishing pad and the substrate surface. Conventionally, in water polishing, water is discharged from a small water discharge nozzle provided together with the polishing liquid supply nozzle or an atomizer.

[0005] Japanese Patent Application Laid-Open No. 2013-99828

[0006] In the water polishing in the conventional device, there are cases where the polishing liquid and polishing debris are not sufficiently removed. If the polishing liquid and polishing debris are not sufficiently removed or the polishing liquid is unevenly removed on the polishing surface, the uniformity of the polishing surface profile after water polishing may be impaired by the remaining polishing liquid.

[0007] The present invention has been made in view of the above circumstances, and one of its objectives is to suitably remove polishing liquid or polishing debris during water polishing after polishing with a polishing liquid. Another objective of the present invention is to improve the uniformity of the polished surface profile in substrate polishing.

[0008] According to one embodiment of the present invention, a polishing apparatus is proposed for polishing an object to be polished using a polishing pad having a polishing surface, comprising: a rotatable polishing table comprising: a polishing table for supporting the polishing pad; a substrate holding portion configured to hold the object to be polished and press the object to be polished against the polishing pad; a polishing liquid supply mechanism configured to supply polishing liquid to the polishing surface; a water supply mechanism configured to supply water to a supply position located in the central region of the polishing surface; and a controller that controls the polishing apparatus to perform a first polishing in which the object to be polished is pressed against the polishing pad while the polishing liquid is supplied from the polishing liquid supply mechanism, and then a second polishing in which the supply of polishing liquid is stopped and water is supplied from the water supply mechanism to the supply position at a flow rate of 5 L / min or more and 15 L / min or less while the object to be polished is pressed against the polishing pad.

[0009] According to one embodiment of the present invention, a polishing method is proposed for polishing an object to be polished by rotating a polishing table to which a polishing pad is attached and pressing the object to be polished against the polishing pad, the method comprising: a first polishing step of polishing the object to be polished by pressing the object to be polished against the polishing pad while supplying polishing liquid to the polishing surface of the polishing pad; and a second polishing step of stopping the supply of polishing liquid and supplying water at a flow rate of 5 L / min or more and 15 L / min or less to a supply position located in the central region of the polishing surface while pressing the object to be polished against the polishing pad.

[0010] This is a perspective view showing the general configuration of a polishing apparatus according to one embodiment of the present invention. This is a diagram showing the general configuration of a polishing apparatus according to one embodiment of the present invention from above. This is a flowchart showing an example of a substrate polishing method performed by a controller. This is a diagram showing a comparative example polishing apparatus from above. This is a diagram showing the size of the irregularities on the polished surface of the substrate after polishing and the uniformity of the polished surface according to this embodiment and the comparative example.

[0011] Embodiments of the present invention will be described below with reference to the drawings. In the drawings, identical or corresponding components are denoted by the same reference numerals, and redundant descriptions are omitted.

[0012] Figure 1 is a perspective view showing the schematic configuration of a polishing apparatus according to one embodiment of the present invention. Figure 2 is a view from above showing the schematic configuration of a polishing apparatus according to one embodiment of the present invention. The polishing apparatus of this embodiment is configured to polish a substrate W, such as a semiconductor wafer, which is the object to be polished, using a polishing pad 1 having a polishing surface 1a. As shown in the figure, the polishing apparatus of this embodiment includes a polishing table 2 that supports the polishing pad 1 and a top ring (substrate holding part) 3 that holds the substrate W and presses it against the polishing pad 1. Furthermore, the polishing apparatus includes a polishing liquid supply mechanism 4 that supplies polishing liquid (slurry) to the polishing pad 1 and a water supply mechanism 30 that supplies water to the polishing pad 1.

[0013] The polishing table 2 is connected via a table shaft 5 to a table motor 6 located below it. This table motor 6 rotates the polishing table 2 in the direction indicated by the arrow. A polishing pad 1 is attached to the polishing table 2 by adhesive or other means. The surface of the polishing pad 1 constitutes the polishing surface 1a.

[0014] The top ring 3 is configured to hold the substrate W, which is to be polished, on its lower surface by vacuum suction or the like. The upper part of the top ring 3 is connected to the top ring arm 8 via the top ring shaft 7. The top ring 3 is movable in the upper direction by an air cylinder (not shown), and its distance from the polishing table 2 can be adjusted. This allows the top ring 3 to press the held substrate W against the upper surface (polishing surface) 1a of the polishing pad 1. The top ring arm 8 is also configured to swing using a motor (not shown), which moves the top ring 3 in a direction parallel to the polishing surface 1a. In this embodiment, the top ring 3 is configured to move between a receiving position for the substrate W (not shown) and a position above the polishing pad 1, and is configured to allow changing the position in which the substrate W is pressed against the polishing pad 1.

[0015] The polishing fluid supply mechanism 4 has a polishing fluid supply nozzle 10 positioned above the polishing table 2 and supplies polishing fluid to the polishing pad 1 supported by the polishing table 2. The polishing fluid supply nozzle 10 is configured to be swingable by a motor (not shown), and the polishing fluid supply mechanism 4 can change the supply position of the polishing fluid during polishing.

[0016] The water supply mechanism 30 is positioned above the polishing table 2 and supplies water (or pure water (DIW)) to the polishing pad 1 supported by the polishing table 2. In this embodiment, the water supply position from which the water supply mechanism 30 supplies water is located in the central region of the polishing surface 1a. Here, the "central region" of the polishing surface 1a means the center or a region near the center of the polishing surface 1a. For example, the central region of the polishing surface 1a can be defined as the region within the range that includes the center when the polishing surface 1a is divided radially into 3, 5, or 7 equal parts. As another example, the central region of the polishing surface 1a can be defined as the region closer to the center of the polishing surface 1a than the center (rotation axis) of the top ring 3 when the substrate W is pressed against the polishing surface 1a by the top ring 3. Furthermore, the supply position means the flow center of the water supplied from the water supply mechanism 30 to the polishing table 2. In this embodiment, the water supply mechanism 30 has a single water supply port, but it may have multiple supply ports. If the water supply mechanism 30 has multiple water supply ports, the flow center (flow rate center) of the water supplied to the polishing surface 1a from the multiple water supply ports should be located in the central region of the polishing surface 1a. The water supply mechanism 30 may be configured integrally with the polishing fluid supply mechanism 4, or it may be configured to move together with the polishing fluid supply nozzle 10 of the polishing fluid supply mechanism 4. Furthermore, the water supply mechanism 30 may be configured integrally with the atomizer 40, or it may be configured to move together with the atomizer 40.

[0017] The water supply mechanism 30 is configured to supply water at a high flow rate to the supply position on the polishing surface 1a. Specifically, the water supply mechanism 30 is configured to supply water at a flow rate of 5 L / min or more, 7 L / min or more, 10 L / min or more, or 12 L / min or more to the supply position on the polishing surface 1a. It is preferable that the water supply mechanism 30 and its supply rate are configured so that excessive splashing of water is prevented from occurring on the polishing surface 1a. For example, the water supply port of the water supply mechanism 30 is preferably located at a distance of 5 cm, 7 cm, or less than 10 cm from the polishing pad 1, and may also be located at a distance of about 1 cm, 2 cm, or 3 cm from the polishing pad 1. Furthermore, it is preferable to supply water at a flow rate of no more than 15 L / min. The water supply port of the water supply mechanism 30 may be located higher than the polishing liquid supply port of the polishing liquid supply mechanism 4 or the supply port 40a of the atomizer 40. Furthermore, splashing can be suppressed by configuring the water supply mechanism 30 with a spray nozzle, or by making the discharge port shape a fan shape, a slit shape, or a structure in which multiple small diameter pipes are bundled or arranged in a narrow area. Also, when water is supplied from the water supply mechanism 30, it is preferable that the supply port of the water supply mechanism 30 be positioned vertically above the central region of the polishing surface 1a. As an example, the water supply from the water supply mechanism 30 to the polishing surface 1a is carried out so that the water flows vertically downward. However, the water supply from the water supply mechanism 30 may be carried out so that the water flows at an inclination relative to the polishing surface 1a.

[0018] The polishing apparatus further includes a dressing apparatus 24 for dressing the polishing pad 1. The dressing apparatus 24 comprises a dresser 26 that slides against the polishing surface 1a of the polishing pad 1, a dresser arm 27 that supports the dresser 26, and a dresser swivel shaft 28 that rotates the dresser arm 27. As the dresser arm 27 rotates, the dresser 26 oscillates on the polishing surface 1a. The lower surface of the dresser 26 forms a dressing surface consisting of numerous abrasive particles such as diamond particles. The dresser 26 rotates while oscillating on the polishing surface 1a, dressing the polishing surface 1a by slightly scraping off the polishing pad 1.

[0019] The polishing apparatus further includes an atomizer 40 that sprays a mist of cleaning fluid onto the polishing surface 1a of the polishing pad 1 to clean the polishing surface 1a. The cleaning fluid is a fluid containing at least a cleaning solution (e.g., pure water). More specifically, the cleaning fluid consists of a mixed fluid of the cleaning solution and a gas (e.g., an inert gas such as nitrogen gas), or the cleaning solution alone. The atomizer 40 has a plurality of supply ports 40a along the radial direction of the polishing pad 1 (or polishing table 2) (see dashed line in Figure 2) and is supported by a support shaft 49. The support shaft 49 is located outside the polishing table 2. The atomizer 40 is located above the polishing surface 1a of the polishing pad 1. The atomizer 40 removes polishing debris and abrasive particles contained in the polishing fluid from the polishing surface 1a of the polishing pad 1 by spraying a high-pressure cleaning fluid onto the polishing surface 1a.

[0020] The polishing apparatus further includes a controller 50 that controls the overall operation of the polishing apparatus. The controller 50 may be configured as a microcomputer equipped with a CPU, memory, etc., that realizes desired functions using software, or it may be configured as a hardware circuit that performs dedicated calculation processing.

[0021] Figure 3 is a flowchart showing an example of a method for polishing a substrate W performed by the controller 50. First, the controller 50 performs a first polishing (slurry polishing) in which the substrate W and the polishing pad 1 come into contact in the presence of polishing fluid (slurry) (step S10). Specifically, the controller 50 rotates the top ring 3 and the polishing table 2 while holding the substrate W on its lower surface. In this state, the controller 50 supplies polishing fluid from the polishing fluid supply mechanism 4 to the polishing surface 1a of the polishing pad 1 and presses the substrate W, held by the top ring 3, against the polishing surface 1a. As a result, the substrate W and the polishing pad 1 move relative to each other while the surface of the substrate W is in contact with the polishing pad 1 in the presence of slurry, and the substrate W is polished.

[0022] After the completion of the first polishing, the controller 50 performs a second polishing (water polishing) in which the substrate W and the polishing pad 1 are brought into contact while water is supplied to the polishing surface 1a (step S20). Specifically, the controller 50 stops the supply of polishing fluid from the polishing fluid supply mechanism 4 and supplies water to the polishing surface 1a from the water supply mechanism 30. Here, the water from the water supply mechanism 30 is supplied at a large flow rate (for example, a flow rate of 5 L / min or more) to a supply position located in the central region of the polishing surface 1a. Although not limited to this, in the second polishing, the pressing load between the substrate W and the polishing pad 1 may be smaller than the pressing load during the first polishing.

[0023] When the second polishing is completed, the controller 50 moves the top ring 3 holding the substrate W to the outside of the polishing table 2, and the polishing of the substrate W is completed. Note that the first and second polishing may be performed only once or multiple times before the polishing of the substrate W is completed. When the polishing of the substrate W is completed, the controller 50 performs a dressing and cleaning process for the polishing pad 1 (step S30). Specifically, the controller 50 moves the dresser 26 onto the polishing pad 1 and rotates the dresser 26 and the polishing table 2. In this state, the controller 50 brings the dresser 26 into contact with the polishing pad 1 and oscillates the dresser 26 on the polishing surface 1a. As a result, the dresser 26 slightly scrapes off the polishing pad 1, and the polishing pad 1 is dressed. The controller 50 also supplies cleaning fluid from the atomizer 40 to the polishing pad 1 to clean the polishing surface 1a. Note that the dressing and cleaning process for the polishing pad 1 may be performed at any time.

[0024] In the polishing apparatus of this embodiment, during the second polishing (water polishing), a large flow rate of water is supplied to a supply position located in the central region of the polishing surface 1a. As a result, as shown by the white arrow in Figure 2, a large flow rate of water flows from the supply position on the polishing surface 1a toward the outer periphery, effectively removing any slurry remaining on the polishing surface 1a. This prevents the profile of the polished surface after water polishing from being damaged by residual slurry during water polishing.

[0025] Figure 4 is a view of the comparative example polishing apparatus from above. In the comparative example polishing apparatus, instead of the water supply mechanism 30, water is sprayed and supplied from multiple supply ports arranged roughly along the radial direction of the atomizer 40, and the second polishing (water polishing) is performed. According to the inventors' observations, in this comparative example polishing apparatus, although the polishing surface 1a is cleaned by the water supply from the atomizer 40, water convection (recirculation) occurs near the atomizer 40, and the water flow that removes the slurry on the polishing surface 1a from the polishing pad 1 is weak and uneven, so slurry tends to remain on the polishing surface 1a.

[0026] Figure 5 shows the size of surface irregularities and the uniformity of the polished substrate after polishing, according to this embodiment and the comparative example. In Figure 5, the polishing apparatus of this embodiment shows data of the polished substrate where water polishing was performed by supplying 10 L / min of water from the water supply mechanism 30 to the supply position. Also in Figure 5, the polishing apparatus of the comparative example shows data of the polished substrate where water polishing was performed by supplying a total of 10 L / min of water from multiple supply ports 40a along the light direction of the atomizer 40. The horizontal axis of Figure 5 shows the distance from the center of the substrate, with information from the central part of the substrate shown as you move to the left, and information from the outer periphery of the substrate shown as you move to the right. The vertical axis of Figure 5 shows the size of surface irregularities and the uniformity of the polished surface, with smaller values ​​(lower values) indicating a better polished surface profile. As shown in Figure 5, in the polishing apparatus of this embodiment, which supplies a large flow rate of water to the central region from the water supply mechanism 30, an improvement in both the size and uniformity of the surface irregularities of the polished substrate after water polishing was observed at all locations compared to the polishing apparatus of the comparative example which supplies a large flow rate of water from the atomizer 40. In the information shown in Figure 5, a wafer with metal wiring formed on it is used as the substrate, and the size of the irregularities generally occurs at the boundary between the metal wiring and the insulating portion. However, it is believed that the polishing surface profile can also be improved by polishing other substrates, such as substrates without metal wiring formed on them, using the polishing apparatus of this embodiment.

[0027] (Modification) In the above embodiment, water is supplied from the water supply mechanism 30 during the second polishing (water polishing). At this time, the controller 50 may change the water supply flow rate from the water supply mechanism 30 based on at least one of the type of polishing pad 1, the condition of the polishing pad 1, and the type of polishing liquid (slurry) supplied from the polishing liquid supply mechanism 4. This is based on the fact that the ease of removing the slurry from the polishing surface 1a differs depending on the type or condition of the polishing pad 1. Here, the condition of the polishing pad 1 may include, for example, the groove shape applied to the polishing surface 1a, the period since replacement, or the number of times the substrate has been polished. Furthermore, this is based on the fact that the ease of removal from the polishing surface 1a differs depending on the type of polishing liquid, and that the optimal degree of removal may differ because the polishing liquid may contain corrosion inhibitors for metal wiring. As an example, a map that pre-determines the relationship between at least one of the type of polishing pad 1, the condition of the polishing pad 1, and the type of slurry, and the water supply flow rate from the water supply mechanism 30 may be created by experimentation or simulation. The controller 50 may then determine the water supply flow rate from the water supply mechanism 30 by applying the information obtained from the external input to the map.

[0028] Furthermore, in the above-described embodiment, in the second polishing, a large flow of water is supplied from the water supply mechanism 30 to a supply position located in the central region of the polishing pad 1, but a small amount of water may also be dripped or supplied outside the central region of the polishing pad 1. For example, in the above-described embodiment, the water supplied from the water supply mechanism 30 to the supply position may be scattered outside the central region of the polishing pad 1, or in addition to the supply of a large flow of water from the water supply mechanism 30, a small amount of water may be supplied outside the central region of the polishing pad 1 from another supply mechanism.

[0029] The embodiment described above can also be described in the following form. [Embodiment 1] According to embodiment 1, a polishing apparatus is proposed for polishing an object to be polished using a polishing pad having a polishing surface, comprising: a rotatable polishing table comprising: a polishing table for supporting the polishing pad; a substrate holding part configured to hold the object to be polished and press the object to be polished against the polishing pad; a polishing liquid supply mechanism configured to supply polishing liquid to the polishing surface; a water supply mechanism configured to supply water to a supply position located in the central region of the polishing surface; and a controller that controls the polishing apparatus to perform a first polishing in which the object to be polished is pressed against the polishing pad while the polishing liquid is supplied from the polishing liquid supply mechanism and the object to be polished is pressed against the polishing pad while the supply of polishing liquid is stopped and water is supplied from the water supply mechanism to the supply position at a flow rate of 5 L / min or more and 15 L / min or less and the object to be polished is pressed against the polishing pad. According to embodiment 1, polishing liquid or polishing debris can be suitably removed in water polishing after polishing with polishing liquid.

[0030] [Embodiment 2] According to Embodiment 2, in Embodiment 1, the polishing apparatus has a plurality of supply ports along the radial direction of the polishing table and is equipped with an atomizer that sprays cleaning fluid onto the polishing surface from the plurality of supply ports, and the controller removes the object to be polished from the polishing pad after the second polishing is performed and cleans the polishing pad by supplying the cleaning fluid from the atomizer. According to Embodiment 2, the polishing pad can be cleaned by supplying cleaning fluid from the atomizer.

[0031] [Embodiment 3] According to Embodiment 3, in Embodiment 1 or 2, the controller is configured to change the water supply flow rate from the water supply mechanism in the second polishing based on at least one of the type of polishing pad, the condition of the polishing pad, and the type of polishing liquid. According to Embodiment 3, the polishing pad can be washed with water based on the type or condition of the polishing pad, or the type of polishing liquid.

[0032] [Embodiment 4] According to Embodiment 4, a polishing method is proposed in which a polishing table to which a polishing pad is attached is rotated and an object to be polished is pressed against the polishing pad to polish the object, the polishing method comprising: a first polishing step in which an object to be polished is pressed against the polishing pad while a polishing liquid is supplied to the polishing surface of the polishing pad to polish the object; and a second polishing step in which the supply of the polishing liquid is stopped and water is supplied at a flow rate of 5 L / min or more and 15 L / min or less to a supply position located in the central region of the polishing surface while the object to be polished is pressed against the polishing pad. According to Embodiment 4, the polishing liquid or polishing debris can be suitably removed in water polishing after polishing with a polishing liquid.

[0033] While embodiments of the present invention have been described above, the embodiments of the invention described above are for the purpose of facilitating understanding of the present invention and do not limit it. The present invention can be modified and improved without departing from its spirit, and of course, the present invention includes equivalents thereof. Furthermore, any combination of embodiments and modifications is possible to the extent that at least some of the above-mentioned problems can be solved or at least some of the effects can be achieved, and any combination or omission of each component described in the claims and specification is possible.

[0034] This application claims priority based on Japanese Patent Application No. 2024-200590, filed on 18 November 2024. All disclosures of Japanese Patent Application No. 2024-200590, including the specification, claims, drawings, and abstract, are incorporated herein by reference in whole. All disclosures of Japanese Patent Publication No. 2013-99828 (Patent Document 1), including the specification, claims, drawings, and abstract, are incorporated herein by reference in whole.

[0035] W...Substrate 1...Polishing pad 1a...Polishing surface 2...Polishing table 3...Top ring 4...Polishing fluid supply mechanism 5...Water supply mechanism 10...Polishing fluid supply nozzle 24...Dressing device 26...Dresser 30...Water supply mechanism 40...Atomizer 50...Controller

Claims

1. A polishing apparatus for polishing an object to be polished using a polishing pad having a polishing surface, comprising: a rotatable polishing table for supporting the polishing pad; a substrate holding section configured to hold the object to be polished and press the object against the polishing pad; a polishing liquid supply mechanism configured to supply polishing liquid to the polishing surface; a water supply mechanism configured to supply water to a supply position located in the central region of the polishing surface; and a controller that controls the polishing apparatus to perform a first polishing in which the object to be polished is pressed against the polishing pad while the polishing liquid is supplied from the polishing liquid supply mechanism, and then a second polishing in which the supply of polishing liquid is stopped and water is supplied from the water supply mechanism to the supply position at a flow rate of 5 L / min or more and 15 L / min or less while the object to be polished is pressed against the polishing pad.

2. The polishing apparatus according to claim 1, wherein the polishing apparatus has a plurality of supply ports along the radial direction of the polishing table and includes an atomizer that sprays cleaning fluid from the plurality of supply ports onto the polishing surface, and the controller removes the object to be polished from the polishing pad after the second polishing is performed and cleans the polishing pad by supplying the cleaning fluid from the atomizer.

3. The polishing apparatus according to claim 1 or 2, wherein the controller is configured to change the water supply flow rate from the water supply mechanism in the second polishing based on at least one of the type of polishing pad, the state of the polishing pad, and the type of polishing liquid.

4. A polishing method comprising rotating a polishing table to which a polishing pad is attached and pressing an object to be polished against the polishing pad to polish the object, the method comprising: a first polishing step of polishing the object to be polished by pressing the object to be polished against the polishing pad while supplying a polishing liquid to the polishing surface of the polishing pad; and a second polishing step of stopping the supply of the polishing liquid and supplying water at a flow rate of 5 L / min or more and 15 L / min or less to a supply position located in the central region of the polishing surface while pressing the object to be polished against the polishing pad.

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