Polishing apparatus
Patent Information
- Application Number
- JP2024119211
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-07-25
- Publication Date
- 2026-02-05
Smart Images
Figure 2026018121000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a polishing apparatus that polishes a substrate such as a semiconductor wafer by sliding it against a polishing pad, and more particularly to a polishing apparatus that polishes a substrate while adjusting the surface temperature of the polishing pad. [Background technology]
[0002] CMP (Chemical Mechanical Polishing) equipment is used in the process of polishing the surface of a substrate in the manufacture of semiconductor devices. The CMP equipment holds the substrate in a polishing head and rotates it, then presses the substrate against a polishing pad on a rotating polishing table to polish the surface of the substrate. During polishing, a polishing liquid (slurry) is supplied to the polishing pad, and the surface of the substrate is flattened by the chemical action of the polishing liquid and the mechanical action of the abrasive grains contained in the polishing liquid.
[0003] The polishing rate of a substrate depends not only on the polishing load of the substrate on the polishing pad, but also on the surface temperature of the polishing pad (i.e., the temperature of the polishing surface). This is because the chemical action of the polishing liquid on the substrate depends on temperature. Therefore, in the manufacture of semiconductor devices, it is important to maintain the surface temperature of the polishing pad at an optimal value during substrate polishing in order to increase the substrate polishing rate and keep it constant. In this specification, the surface temperature of the polishing pad is sometimes referred to as the "pad temperature."
[0004] Therefore, pad temperature adjustment devices for adjusting the pad temperature have been used conventionally (see, for example, Patent Document 1). The pad temperature adjustment device described in Patent Document 1 includes a pad heater that sprays a heating fluid onto the surface of the polishing pad, and a pad cooler that sprays a cooling fluid onto the surface of the polishing pad. By adjusting the flow rates of the heating fluid and the cooling fluid supplied to the pad heater and the pad cooler, respectively, the pad temperature during substrate polishing can be adjusted and maintained at a desired temperature. [Prior art documents] [Patent documents]
[0005] [Patent Document 1] Japanese Patent Publication No. 2022-170648 Summary of the Invention [Problem to be solved by the invention]
[0006] Since the chemical action of the polishing liquid on the substrate depends on temperature, a decrease in pad temperature generally decreases the substrate removal rate. On the other hand, depending on the type of polishing pad, a decrease in pad temperature may increase the hardness of the polishing pad, thereby increasing the removal rate.
[0007] Therefore, in recent years, there has been a demand for lowering the pad temperature to a temperature (e.g., 0°C) lower than room temperature (e.g., the ambient temperature around the polishing pad) in order to more precisely control the polishing rate and improve the in-plane uniformity of the polished substrate. Furthermore, for the same reason, users of polishing apparatuses sometimes desire to quickly lower the pad temperature, once it has been raised to a high temperature, to a target temperature.
[0008] Therefore, a polishing apparatus is provided that can precisely control the polishing rate by quickly lowering the pad temperature to a temperature lower than room temperature. [Means for solving the problem]
[0009] In one aspect, a polishing apparatus is provided, comprising: a rotatable polishing table that supports a polishing pad; a polishing head that polishes a substrate by pressing the substrate against the polishing surface of the rotating polishing pad; at least one pad temperature measuring device that measures the temperature of the polishing surface; a pad temperature adjusting device that adjusts the temperature of the polishing surface; and a control device that controls the operation of the pad temperature adjusting device based on the temperature of the polishing surface measured by the at least one pad temperature measuring device, wherein the pad temperature adjusting device includes at least one cooling nozzle that sprays a coolant onto the polishing surface and at least one gas nozzle that sprays a dry gas onto the polishing surface, and the coolant has a boiling point below ambient temperature.
[0010] In one embodiment, the cooling nozzle is disposed between the polishing head and the gas nozzle when viewed in the rotation direction of the polishing table. In one embodiment, the at least one cooling nozzle is a plurality of cooling nozzles arranged corresponding to each of a plurality of regions radially divided into the polishing table, and the control device independently controls the temperature of each of the plurality of regions by controlling the flow rate of the coolant supplied to each cooling nozzle. In one embodiment, the at least one pad temperature measuring device is a plurality of pad temperature measuring devices capable of measuring the temperature of each of the plurality of regions.
[0011] In one embodiment, the pad temperature adjustment device further includes a heater for heating the polishing surface, the heater being positioned between the polishing head and the at least one cooling nozzle when viewed in the direction of rotation of the polishing table. In one embodiment, the coolant is dry ice. [Effects of the Invention]
[0012] Since a coolant having a boiling point below the ambient temperature is used to lower the pad temperature, the substrate can be polished at a pad temperature lower than the ambient temperature. That is, the polishing apparatus can polish a substrate while controlling the pad temperature over a wider temperature control range than conventional polishing apparatuses. Furthermore, since the pad temperature can be lowered more quickly, the substrate can be polished more precisely than conventional polishing apparatuses, and the in-plane uniformity of the polished substrate can be improved. [Brief explanation of the drawings]
[0013] [Figure 1] FIG. 1 is a schematic diagram showing a polishing apparatus according to one embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a cooling machine according to one embodiment. [Figure 3] FIG. 3 is a schematic diagram showing a gas injector according to one embodiment. [Figure 4] FIG. 4 is a schematic diagram showing an example of the arrangement of cooling nozzles and gas nozzles according to one embodiment. [Figure 5] FIG. 5 is a schematic diagram showing the compressed gas containing the coolant being sprayed from the cooling nozzle. [Figure 6] FIG. 6(a) is a schematic diagram showing a cooling nozzle according to another embodiment, and FIG. 6(b) is a schematic cross-sectional view of the cooling nozzle shown in FIG. 6(a). [Figure 7] FIG. 7 is a schematic diagram showing a heater according to one embodiment. [Figure 8] FIG. 8 is a schematic diagram showing an example of a position adjustment mechanism that can adjust the inclination and height of the cooling nozzle relative to the polishing pad. [Figure 9] FIG. 9 is a schematic diagram showing another example of the position adjustment mechanism. [Figure 10] FIG. 10 is a schematic diagram showing a common nozzle in which a heating nozzle of a heater, a cooling nozzle of a cooler, and a gas nozzle of a gas injector are integrally formed. DETAILED DESCRIPTION OF THE INVENTION
[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing a polishing apparatus according to one embodiment. The polishing apparatus shown in Fig. 1 includes a polishing head 1 that holds and rotates a wafer W, which is an example of a substrate, a polishing table 2 that supports a polishing pad 3, a polishing liquid supply nozzle 4 that supplies a polishing liquid (e.g., a slurry) to the surface of the polishing pad 3, a pad temperature measuring device 10 that measures the temperature of the surface of the polishing pad 3, and a pad temperature adjusting device 5 that adjusts the surface temperature of the polishing pad 3. The surface (upper surface) of the polishing pad 3 forms a polishing surface that polishes the wafer W.
[0015] Furthermore, the polishing apparatus has a control device 40 that controls the operation of the pad temperature adjusting device 5 based on the temperature of the polishing surface of the polishing pad 3 (i.e., the pad temperature) measured by the pad temperature measuring device 10. In this embodiment, the control device 40 is configured to control the operation of the entire polishing apparatus including the pad temperature adjusting device 5.
[0016] The polishing head 1 is movable in the vertical direction and can rotate around its axis in the direction indicated by the arrow. The wafer W is held on the underside of the polishing head 1 by vacuum suction or the like. A motor (not shown) is connected to the polishing table 2, which can rotate in the direction indicated by the arrow. As shown in FIG. 1, the polishing head 1 and the polishing table 2 rotate in the same direction. A polishing pad 3 is attached to the upper surface of the polishing table 2.
[0017] Polishing of a wafer W is performed as follows. The wafer W to be polished is held by and rotated by a polishing head 1. Meanwhile, a polishing pad 3 is rotated together with a polishing table 2. In this state, a polishing liquid is supplied to the surface of the polishing pad 3 from a polishing liquid supply nozzle 4, and the surface of the wafer W is pressed against the surface of the polishing pad 3 (i.e., the polishing surface) by the polishing head 1. The surface of the wafer W is polished by sliding contact with the polishing pad 3 in the presence of the polishing liquid. The surface of the wafer W is planarized by the chemical action of the polishing liquid and the mechanical action of the abrasive grains contained in the polishing liquid.
[0018] 1 includes a cooler 50 for spraying a coolant onto the polishing surface of the polishing pad 3 to cool the polishing surface, and a gas injector 60 for spraying dry gas onto the polishing surface. The cooler 50 includes at least one cooling nozzle disposed above the polishing pad 3, from which the coolant is sprayed. The configuration of the cooler 50 will be described later.
[0019] The coolant is a material used to lower the pad temperature and has a boiling point below ambient temperature. In this specification, ambient temperature refers to the ambient temperature of the polishing table 2 and / or polishing pad 3, unless otherwise specified. Examples of coolants include solids that sublimate at room temperature and pressure, such as dry ice, and liquids, such as liquefied gases (e.g., liquid nitrogen, liquid oxygen, liquid helium, liquefied carbon dioxide, and liquid hydrogen). However, the type of coolant is not limited to these examples. The coolant may be in the form of a liquid, solid, or gas, as long as it has a boiling point below ambient temperature. In this embodiment, dry ice, which is solidified carbon dioxide, is used as the coolant. Dry ice has a boiling point (sublimation point) of −78.5°C at room temperature and pressure and directly sublimates into a gas. Dry ice is also a relatively inexpensive material that is readily available on the market.
[0020] Fig. 2 is a schematic diagram showing a chiller according to one embodiment. The chiller 50 shown in Fig. 2 includes a plurality of (six in Fig. 2) cooling nozzles 51, a coolant source 52, a coolant line 53 connecting the cooling nozzles 51 and the coolant source 52, a main valve 54 disposed in the coolant line 53, a coolant flow regulator 55 disposed in the coolant line 53, and a pumping line 57 connected to the coolant source 52.
[0021] Coolant source 52 is, for example, a container such as a cylinder that stores the above-mentioned coolant. Pressure supply line 57 is a line through which gas having a predetermined pressure (hereinafter referred to as pressure supply gas) flows, and this pressure supply gas transports the coolant stored in coolant source 52 to cooling nozzle 51 via coolant line 53. The pressure supply gas containing the coolant is sprayed from cooling nozzle 51. The type of pressure supply gas can be freely selected as long as it can transport the coolant to cooling nozzle 51. However, the pressure supply gas is preferably an inert gas such as nitrogen, argon, or helium so as not to deteriorate the coolant and polishing liquid and to not adversely affect devices formed on wafer W.
[0022] The coolant line 53 is composed of a main coolant line 53a connected to the coolant source 52, and branch coolant lines 53b branching from the main coolant line 53a and extending to each cooling nozzle 51. A main valve 54 is disposed in the main coolant line 53a, and a coolant flow regulator 55 is disposed in each of the branch coolant lines 53b.
[0023] The main valve 54 and the coolant flow regulator 55 are connected to the control device 40 (see FIG. 1), which controls the operation of the main valve 54 and the coolant flow regulator 55. Each coolant flow regulator 55 is configured to be able to control the flow rate of the pressurized gas containing the coolant that is sprayed from the tip of the cooling nozzle 51. In this specification, the pressurized gas containing the coolant will sometimes be simply referred to as the "coolant," and the flow rate of the pressurized gas containing the coolant will sometimes be simply referred to as the "coolant flow rate."
[0024] The coolant flow regulator 55 may be a mass flow controller or a combination of an electro-pneumatic regulator and a flow meter. When the coolant flow regulator 55 is a combination of an electro-pneumatic regulator and a flow meter, the control device 40 controls the operation of the electro-pneumatic regulator based on the measurement value of the flow meter to adjust the pressure of the pressurized gas containing coolant flowing through the coolant branch line 53b. By changing the pressure of the pressurized gas flowing through the coolant branch line 53b, the flow rate of the pressurized gas containing coolant sprayed from the cooling nozzle 51 can be changed.
[0025] In the illustrated example, multiple coolant flow regulators 55 are arranged in the coolant branch lines 53b. However, one coolant flow regulator 55 may be arranged in the main coolant line 53a. In this case, the control device 40 collectively controls the flow rates of the coolant sprayed from each cooling nozzle 51 by adjusting the flow rate of the compressed gas containing the coolant flowing through the main coolant line 53a.
[0026] The cooling nozzle 51 is configured to spray granular dry ice as a coolant from its tip together with the pressurized gas. In this embodiment, the coolant line 53 has thermal insulation so that the dry ice does not completely evaporate or liquefy midway through the coolant line 53. The coolant flow regulator 55 is configured to be able to measure and adjust the flow rate of the pressurized gas containing the granular coolant. Such cooling nozzles 51, coolant lines 53, and coolant flow regulators 55 are commercially available, and dry ice particles having a particle diameter of, for example, 0.1 to 200 μm are sprayed from the cooling nozzle 51 together with the pressurized gas.
[0027] The coolant is sprayed from the cooling nozzle 51 of the cooler 50 during polishing of the wafer W. The coolant sprayed from the cooling nozzle 51 first cools the polishing liquid on the polishing pad 3. Furthermore, a portion of the coolant that passes through the polishing liquid and reaches the polishing surface of the polishing pad 3 directly cools the polishing surface. That is, the coolant can quickly lower the pad temperature indirectly via the polishing liquid and also by direct contact. As a result, the pad temperature can be efficiently lowered. Furthermore, in this embodiment, the coolant is dry ice, which has a boiling point of 0°C or below, so it is also possible to quickly lower the pad temperature to a temperature below 0°C.
[0028] Fig. 3 is a schematic diagram showing a gas injector according to one embodiment. In the embodiment shown in Fig. 3, a gas injector 60 includes a plurality of dry gas nozzles 61 (six in Fig. 3) for injecting dry gas onto the polishing surface, a dry gas source 62, a dry gas line 63 connecting the dry gas nozzles 61 and the dry gas source 62, a dry gas main valve 64 disposed on the dry gas line 63, and a dry gas flow regulator 65 disposed on the dry gas line 63.
[0029] The dry gas is, for example, a gas having a humidity lower than that of the atmosphere surrounding the polishing table 2 and / or polishing pad 3. The dry gas is preferably an inert gas such as nitrogen, argon, or helium so as not to alter the coolant and polishing liquid and to avoid adversely affecting devices formed on the wafer W. Alternatively, the dry gas may be dry air. The dry gas source 62 is, for example, a utility line of a factory in which the polishing apparatus is located.
[0030] The dry gas line 63 is composed of a dry gas main line 63a connected to the dry gas source 62, and dry gas branch lines 63b branching from the dry gas main line 63a and extending to each dry gas nozzle 61. A dry gas main valve 64 is disposed in the dry gas main line 63a, and a dry gas flow regulator 65 is disposed in each of the dry gas branch lines 63b.
[0031] The dry gas main valve 64 and the dry gas flow regulator 65 are connected to the control device 40 (see FIG. 1 ), which controls the operation of the dry gas main valve 64 and the dry gas flow regulator 65. The dry gas flow regulator 65 is configured to control the flow rate of the dry gas injected from the tip of the dry gas nozzle 61. The dry gas flow regulator 65 may be a mass flow controller or a combination of an electropneumatic regulator and a flow meter. When the dry gas flow regulator 65 is a combination of an electropneumatic regulator and a flow meter, the control device 40 controls the operation of the electropneumatic regulator based on the measurement value of the flow meter to adjust the pressure of the dry gas flowing through the dry gas branch line 63b. The flow rate of the dry gas injected from the dry gas nozzle 61 can be changed by changing the pressure of the dry gas flowing through the dry gas branch line 63b.
[0032] In the illustrated example, multiple dry gas flow regulators 65 are arranged in the dry gas branch line 63b. However, one dry gas flow regulator 65 may be arranged in the dry gas main line 63a. In this case, the control device 40 collectively controls the flow rates of the dry gas injected from each dry gas nozzle 61 by adjusting the flow rate of the dry gas flowing through the dry gas main line 63a.
[0033] The dry gas is a gas that prevents the coolant sprayed from the cooling nozzle 51 onto the polishing pad 3 from reaching the polishing head 1, i.e., the wafer W being polished, due to the rotation of the polishing table 2. If the particulate coolant reaches the wafer W being polished, it may become trapped between the wafer W and the polishing pad 3, potentially damaging devices formed on the wafer W. If the coolant is in liquid form, it may adversely affect devices formed on the wafer W. Therefore, the dry gas increases the rate at which the coolant evaporates (hereinafter sometimes referred to as the "evaporation speed"), preventing the coolant from reaching the wafer W being polished.
[0034] By spraying the dry gas onto the polishing pad 3, the vaporized coolant layer surrounding the coolant is blown away, thereby increasing the evaporation speed of the coolant. Furthermore, the coolant sprayed onto the polishing pad 3 has a very low temperature because it is surrounded by a vaporized coolant layer. Therefore, by blowing away the vaporized coolant layer surrounding the coolant with the dry gas, the ambient temperature of the coolant can be increased. From this perspective, the evaporation speed of the coolant can also be increased. Furthermore, the presence of dry gas with low humidity around the coolant can also increase the evaporation speed of the coolant. The flow rate of the dry gas sprayed from the dry gas nozzle 61 is adjusted to an amount that can evaporate the coolant quickly enough so that the coolant does not reach the polishing head 1.
[0035] Fig. 4 is a schematic diagram showing an example of the arrangement of cooling nozzles and gas nozzles according to one embodiment. Fig. 5 is a schematic diagram showing pressurized gas containing a coolant being sprayed from a cooling nozzle. Fig. 4 corresponds to a view of the polishing pad 3 as seen from above, and Fig. 5 corresponds to a view of the polishing pad 3 as seen from the side.
[0036] As shown in FIG. 4, the multiple cooling nozzles 51 are arranged linearly in the radial direction of the polishing pad 3. As shown in FIG. 5, the multiple cooling nozzles 51 are arranged so that the pressurized gas sprayed from the multiple cooling nozzles 51 collides with the entire range from the center line CP of the polishing pad 3 to the outer periphery. The multiple cooling nozzles 51 are responsible for cooling multiple regions Z1-Z6 of the polishing pad 3, respectively (see FIG. 5). The multiple regions Z1-Z6 are virtual regions set corresponding to the multiple cooling nozzles 51 and are set concentrically. The centralmost region Z1 is a circular region. By arranging the multiple cooling nozzles 51 in this manner, the entire polishing pad 3 can be cooled.
[0037] Although not shown, as long as the entire polishing pad 3 can be cooled by the coolant sprayed from the multiple cooling nozzles 51, the multiple cooling nozzles 51 do not need to be arranged linearly in the radial direction of the polishing pad 3.
[0038] Furthermore, the number of cooling nozzles 51 can be freely selected as long as the entire polishing pad 3 can be cooled by the coolant sprayed from the multiple cooling nozzles 51. For example, as shown in Figures 6(a) and 6(b), the pad temperature adjustment device 5 may have a single cooling nozzle 51 having a long portion 51a extending substantially in the radial direction of the polishing pad 3 and an ejection port 51b for ejecting the coolant toward the polishing surface of the polishing pad 3. In this case, the ejection port 51b has a slit shape formed along the longitudinal direction of the long portion 51a, and is formed so that the coolant impinges on the entire range from the center CP (see Figures 4 and 5) of the polishing pad 3 to the outer periphery.
[0039] In this embodiment, the dry gas nozzles 61 are arranged corresponding to the cooling nozzles 51 (see FIG. 4). That is, the multiple dry gas nozzles 61 are arranged corresponding to the multiple regions Z1-Z6 of the polishing pad 3, and are arranged linearly in the radial direction of the polishing pad 3. Note that the multiple dry gas nozzles 61 do not need to be arranged linearly in the radial direction of the polishing pad 3, as long as the coolant sprayed from the cooling nozzles 51 can be prevented from reaching the polishing head 1. Furthermore, the number of dry gas nozzles 61 can be freely selected, as long as the coolant sprayed from the cooling nozzles 51 can be prevented from reaching the polishing head 1. Although not shown, like the cooling nozzle 51 described with reference to FIGS. 6(a) and 6(b), the pad temperature adjustment device 5 may have a single dry gas nozzle 61 having a long portion extending approximately in the radial direction of the polishing pad 3 and an injection port for spraying dry gas toward the polishing surface of the polishing pad 3.
[0040] As shown in FIG. 4, the cooling nozzle 51 is disposed between the polishing head 1 and the plurality of dry gas nozzles 61 in the rotation direction of the polishing table 2 (i.e., the polishing pad 3). In other words, the cooling nozzle 51 is located upstream of the gas injector 60 having the plurality of dry gas nozzles 61 in the rotation direction of the polishing table 2, and downstream of the polishing head 1 in the rotation direction of the polishing table 2. By arranging the cooling nozzle 51 and the dry gas nozzle 61 in this manner, it is possible to prevent a portion of the coolant sprayed from the cooling nozzle 51 from being blown away by the dry gas sprayed from the dry gas nozzle 61, thereby enabling the coolant to exhibit the desired cooling performance and the dry gas to exhibit the desired evaporation performance.
[0041] The polishing apparatus may have one pad temperature measuring device 10 as shown in FIG. 1, or may have multiple pad temperature measuring devices 10 corresponding to the number of regions Z1-Z6 as shown in FIG. 4. That is, the polishing apparatus only needs to have at least one pad temperature measuring device 10. The pad temperature measuring device 10 is disposed between the gas injector 60 and the polishing head 1 in the rotation direction of the polishing table 2. In other words, the pad temperature measuring device 10 is located upstream of the polishing head 1 in the rotation direction of the polishing table 2 and downstream of the gas injector 60 in the rotation direction of the polishing table 2.
[0042] The pad temperature measuring device 10 measures the pad surface temperature in a non-contact manner and sends the measurement value to the control device 40. The pad temperature measuring device 10 may be an infrared radiation thermometer or a thermocouple thermometer that measures the surface temperature of the polishing pad 3, or may be a temperature distribution measuring device that obtains the temperature distribution (temperature profile) of the polishing pad 3 along the radial direction of the polishing pad 3. Examples of temperature distribution measuring devices include thermography, thermopiles, and infrared cameras. When the polishing apparatus has a single pad temperature measuring device 10, the pad temperature measuring device 10 is configured to measure the surface temperature distribution of the polishing pad 3 in a region that includes the center and outer periphery of the polishing pad 3 and extends in the radial direction of the polishing pad 3. In this specification, the temperature distribution (temperature profile) indicates the relationship between the pad surface temperature and the radial position on the wafer W. The control device 40 can obtain each pad temperature in multiple regions Z1-Z6 of the polishing pad 3 from the measurements of the pad temperature measuring device 10.
[0043] Returning to FIG. 1, the polishing apparatus according to this embodiment has a heater 9 that heats the polishing surface of the polishing pad 3. FIG. 7 is a schematic diagram showing a heater according to one embodiment. The heater 9 shown in FIG. 7 includes at least a heating nozzle 11 disposed above the polishing pad 3 and a heating fluid supply system 30 that supplies a heating fluid to the heating nozzle 11. The heating fluid supplied to the heating nozzle 11 via the heating fluid supply system 30 is sprayed onto the polishing surface of the polishing pad 3, thereby heating the polishing surface to a predetermined target temperature.
[0044] In the following, with reference to FIG. 7, an example will be described in which the heating fluid supplied from the heating fluid supply system 30 to the heating nozzle 11 is superheated steam. However, the heating fluid is not limited to this example. The heating fluid may be a high-temperature gas (for example, high-temperature air, nitrogen, or argon) or may be heated steam. Note that superheated steam refers to high-temperature steam obtained by further heating saturated steam.
[0045] Furthermore, the heater 9 described below is a non-contact heater that raises the pad temperature by spraying a heating fluid onto the polishing surface of the polishing pad 3, but the heater 9 is not limited to this example as long as the heater 9 can raise the pad temperature to a desired target temperature. For example, the heater 9 may be a heater that contacts the polishing surface of the polishing pad 3.
[0046] 7 includes a superheated steam generator 31, a superheated steam supply line 32 extending from the superheated steam generator 31 to the heating nozzle 11, a water supply line 33 for supplying water to the superheated steam generator 31, and a gas supply line 34 for supplying room temperature gas to the superheated steam generator 31. The gas supply line 34 extends from a gas supply source (not shown) to the superheated steam generator 31.
[0047] The superheated steam generator 31 mixes water supplied from a water supply line 33 with room temperature gas supplied from a gas supply line 34 to generate superheated steam adjusted to a predetermined temperature. The superheated steam is supplied to the heating nozzle 11 via the superheated steam supply line 32 and sprayed from the heating nozzle 11 onto the polishing surface of the polishing pad 3. This operation can raise the temperature of the polishing surface of the polishing pad 3.
[0048] 7 further includes a flow regulator 35 disposed in the superheated steam supply line 32, and an exhaust line 36 branching off from the superheated steam supply line 32 upstream of the flow regulator 35. The flow regulator 35 can adjust the flow rate of the superheated steam supplied to the heating nozzle 11. Excess superheated steam is exhausted from the polishing apparatus through the exhaust line 36.
[0049] The control device 40 is connected to the superheated steam generator 31 and the flow regulator 35. The control device 40 controls the operation of the superheated steam generator 31 and the flow regulator 35 based on the measurement value of the pad temperature measuring device 10.
[0050] When polishing a wafer W using the polishing apparatus configured as described above, the control device 40 controls the operation of the pad temperature regulator 5 based on the measurement value of the pad temperature measuring device 10 to adjust the temperature of the polishing surface of the polishing pad 3 (i.e., the pad temperature) to a desired temperature. More specifically, the control device 40 adjusts the flow rate of the heating fluid sprayed from the heating nozzle 11 of the heater 9 and / or the flow rate of the pressurized gas containing a coolant sprayed from the cooling nozzle 51 of the cooler 50 to adjust the pad temperature to a desired temperature. The control device 40, which performs such control, controls, for example, the operation of the heater 9 to raise the pad temperature to a first polishing temperature higher than room temperature, thereby performing the first polishing of the wafer W. Then, the control device 40 controls at least the operation of the cooler 50 to lower the pad temperature to a second polishing temperature lower than the first polishing temperature, thereby performing the second polishing of the wafer W.
[0051] By combining such multiple polishing processes, the wafer W can be polished more precisely. According to the polishing apparatus described above, the pad temperature is lowered using a coolant having a boiling point below ambient temperature (or below room temperature), so the wafer W can be polished at a second polishing temperature set lower than ambient temperature (or room temperature). In other words, the polishing apparatus described above can polish the wafer W while controlling the pad temperature over a wider temperature control range than conventional polishing apparatuses. Furthermore, since the pad temperature can be quickly lowered from the first polishing temperature to the second polishing temperature, the wafer W can be polished more precisely than conventional polishing apparatuses, and the in-plane uniformity of the polished wafer W can be improved.
[0052] When lowering the pad temperature from the first polishing temperature to the second polishing temperature, the pad temperature can be quickly raised to the second polishing temperature by using only the cooler 50. On the other hand, by using the cooler 50 and the heater 9 in combination, the control device 40 can freely control the rate at which the pad temperature is lowered from the first polishing temperature to the second polishing temperature.
[0053] For example, assume that the control device 40 stores an intermediate temperature set between the first polishing temperature and the second polishing temperature. In this case, the control device 40 controls only the operation of the cooler 50 until the pad temperature reaches the intermediate temperature, thereby rapidly lowering the pad temperature to the intermediate temperature. Next, the control device 40 may control the operation of both the cooler 50 and the heater 9 until the pad temperature reaches the second polishing temperature from the intermediate temperature, thereby gradually raising the pad temperature to the second polishing temperature. This type of control can effectively prevent the pad temperature from falling significantly below the second polishing temperature (the so-called hunting phenomenon).
[0054] As shown in FIG. 4, when the cooler 50 has a plurality of cooling nozzles 51 and the polishing apparatus has a plurality of pad temperature measuring devices 10 corresponding to the cooling nozzles 51, the control device 40 can independently control the pad temperatures in the plurality of zones Z1-Z6 (see FIG. 5) described above. When performing such control, it is preferable that the cooler 50 has a plurality of coolant flow regulators 55 arranged in each coolant branch line 53b, and the gas injector 60 has a plurality of dry gas flow regulators 65 arranged in each dry gas branch line 63b, as described with reference to FIGS. 2 and 3. If the polishing apparatus has such a configuration, the control device 40 can easily control the flow rate of the coolant flowing through each coolant branch line 53b and the flow rate of the dry gas flowing through each dry gas branch line 63b.
[0055] 8 is a schematic diagram showing an example of a position adjustment mechanism that can adjust the inclination and height of the cooling nozzles 51 relative to the polishing pad. The position adjustment mechanism 90 shown in Fig. 8 includes a nozzle bracket 91 connected to the end of each cooling nozzle 51, a holding bracket 92 to which the nozzle bracket 91 is connected, and a fastener 93 that connects the nozzle bracket 91 to the holding bracket 92.
[0056] In this embodiment, the holding bracket 92 is fixed to a stationary member (not shown) such as a beam of the polishing apparatus. Furthermore, an elongated hole 92a is formed in the holding bracket 92. The elongated hole 92a extends in a direction perpendicular to the polishing surface of the polishing pad 3. In other words, the major axis of the elongated hole 92a extends in a direction perpendicular to the polishing surface of the polishing pad 3.
[0057] In this embodiment, the fastener 93 is made up of a bolt and a nut, and the nozzle bracket 91 is formed with a through hole (not shown) into which the bolt of the fastener 93 can be inserted. By inserting the bolt of the fastener 93 into the through hole of the nozzle bracket 91 and the elongated hole 92a of the holding bracket 92 and then tightening the nut onto the bolt, the cooling nozzle 51 is held to the polishing apparatus via the nozzle bracket 91 and the holding bracket 92.
[0058] By loosening the nut of the fastener 93 and changing the angle of the nozzle bracket 91 relative to the holding bracket 92, it is possible to change (adjust) the inclination of the cooling nozzle 51 relative to the polishing surface of the polishing pad 3. Furthermore, by moving the bolt of the fastener 93 together with the nozzle bracket 91 within the elongated hole 92a of the holding bracket 92 while the nut of the fastener 93 is loosened, it is possible to adjust the vertical position of the cooling nozzle 51 relative to the polishing surface of the polishing pad 3.
[0059] Fig. 9 is a schematic diagram showing another example of a position adjustment mechanism. The position adjustment mechanism 90 shown in Fig. 9 is composed of a rotation device 95 connected to the rear end of the cooling nozzle 51 and a vertical movement device 96 that connects the rotation device 95 to a holding bracket 92 and moves the cooling nozzle 51 and the rotation device 95 along the holding bracket 92. The rotation device 95 is, for example, a motor (e.g., a servo motor or a stepping motor) that rotates the cooling nozzle 51 relative to the polishing surface of the polishing pad 3. The vertical movement device 96 is, for example, composed of a rail 96a formed on the holding bracket 92, a connector 96b that connects the rotation device 95 to the rail 96a, and a motor (e.g., a servo motor or a stepping motor) 96c that moves the connector 96b along the rail 96a.
[0060] The rotation device 95 and the vertical movement device 96 of the position adjustment mechanism 90 are connected to the control device 40, and the operation of the rotation device 95 and the vertical movement device 96 is controlled by the control device 40. With this configuration, the inclination and height of the cooling nozzle 51 relative to the polishing surface of the polishing pad 3 can be automatically adjusted.
[0061] When pressurized gas containing a coolant is sprayed from cooling nozzle 51 onto the polishing surface of polishing pad 3, the pressurized gas colliding with the polishing surface can cause the polishing liquid on the polishing surface to splash. If the polishing liquid splashes from the polishing surface, the desired removal rate may not be achieved, and the splashed polishing liquid may contaminate components of the polishing apparatus, such as polishing table 2. Therefore, the inclination and height of cooling nozzle 51 relative to the polishing surface of polishing pad 3 can be adjusted to prevent the polishing liquid from splashing.
[0062] It should be noted that repeated polishing of the wafer W will wear down the surface of the polishing pad 3, and as a result, the inclination and height of the cooling nozzle 51 relative to the polishing surface of the polishing pad 3 will gradually change. For this reason, it is preferable that the position adjustment mechanism 90 has a configuration that can automatically adjust the inclination and height of the cooling nozzle 51 relative to the polishing surface of the polishing pad 3, as described with reference to FIG.
[0063] 10 is a schematic diagram showing a common nozzle in which the heating nozzle of the heater, the cooling nozzle of the cooler, and the gas nozzle of the gas injector are integrated. As shown in FIG. 10, the pad temperature adjustment device 5 may have a common nozzle 99 in which the heating nozzle 11 of the heater 9, the cooling nozzle 51 of the cooler 50, and the dry gas nozzle 61 of the gas injector 60 are integrated.
[0064] The common nozzle 99 has a first outlet 99a that functions as the above-mentioned heating nozzle 11, a second outlet 99b that functions as the above-mentioned cooling nozzle 51, and a third outlet 99c that functions as the above-mentioned dry gas nozzle 61. The above-mentioned coolant line 53, dry gas line 63, and superheated steam supply line 32 are connected to the common nozzle 99, and superheated steam is injected from the first outlet 99a, pressurized gas containing a coolant is injected from the second outlet 99b, and dry gas is injected from the third outlet 99c.
[0065] When a polishing apparatus has such a common nozzle 99, the cooling nozzle 51 in the common nozzle 99 is located between the heating nozzle 11 and the dry gas nozzle 61 in the rotation direction of the polishing table 2. That is, the second outlet 99b is located between the first outlet 99a and the third outlet 99c in the rotation direction of the polishing table 2. In other words, the second outlet 99b is located upstream of the third outlet 99c in the rotation direction of the polishing table 2, and downstream of the first outlet 99a in the rotation direction of the polishing table 2.
[0066] 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 be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims. [Explanation of symbols]
[0067] 1 polishing head 2 Polishing table 3 polishing pads 5 Pad temperature control device 10 Pad Temperature Meter 11 Heated nozzle 40 Control device 50 Cooler 51 Cooling nozzle 52 Coolant source 53 Coolant Line 54 Former Barrister 55 Coolant flow regulator 57 Pressure Line 60 Gas Injector 61 Dry gas nozzle 62 Dry Gas Source 63 Dry Gas Line 64 Dry gas main valve 65 Dry gas flow regulator
Claims
1. a rotatable polishing table supporting a polishing pad; a polishing head that presses the substrate against the polishing surface of the rotating polishing pad to polish the substrate; at least one pad temperature measuring device for measuring the temperature of the polishing surface; a pad temperature adjusting device for adjusting the temperature of the polishing surface; a control device that controls the operation of the pad temperature adjustment device based on the temperature of the polishing surface measured by the at least one pad temperature measuring device; The pad temperature adjustment device is at least one cooling nozzle for spraying a coolant onto the polishing surface; at least one gas nozzle for injecting a dry gas onto the polishing surface; The coolant has a boiling point below ambient temperature.
2. 2. The polishing apparatus according to claim 1, wherein the cooling nozzle is disposed between the polishing head and the gas nozzle when viewed in the direction of rotation of the polishing table.
3. the at least one cooling nozzle comprises a plurality of cooling nozzles arranged corresponding to a plurality of regions obtained by dividing the polishing table in a radial direction, 2. The polishing apparatus according to claim 1, wherein the control device controls the flow rate of the coolant supplied to each cooling nozzle, thereby independently controlling the temperature of each of the plurality of regions.
4. 4. The polishing apparatus according to claim 3, wherein said at least one pad temperature measuring device comprises a plurality of pad temperature measuring devices capable of measuring the temperatures of said plurality of regions, respectively.
5. the pad temperature adjustment device further includes a heater for heating the polishing surface; 2. The polishing apparatus according to claim 1, wherein the heater is disposed between the polishing head and the at least one cooling nozzle when viewed in the direction of rotation of the polishing table.
6. The polishing apparatus of claim 1 , wherein the coolant is dry ice.
Citation Information
Patent Citations
Polishing device, and polishing method
JP2022170648A