JP2024083854A - How to polish a workpiece - Google Patents

Abstract

[Problem] To polish a workpiece to a flat surface. [Solution] The method includes a polishing step in which a polishing liquid is supplied to a workpiece (W) held on a holding table (20) having an internal flow path (23) through which a medium for temperature adjustment is supplied, while the workpiece (W) is polished with a polishing pad (12), a measurement step in which at least one of the temperature of the holding table (20), the temperature of the polishing pad (12), the temperature of the drained medium, the amount of polishing of the workpiece (W), and the temperature of the drained polishing liquid is measured, and a medium adjustment step in which at least one of the temperature and flow rate of the medium is changed depending on the results of the measurement step. [Selected Figure] Figure 1

Description

The present invention relates to a method for polishing a workpiece.

When a workpiece is polished using a processing device, frictional heat generated between the polishing pad and the workpiece can cause thermal expansion of the workpiece, which is the object to be processed, and components around the processing point, such as the holding table that holds the workpiece. This thermal expansion can hinder the workpiece from being polished flat.

To address this issue, a holding table with a flow path through which a cooling medium flows has been proposed to remove processing heat such as frictional heat (for example, Patent Document 1).

JP 2014-237200 A

However, even if the above-mentioned holding table is used and the cooling medium is continuously supplied under constant conditions, if the processing time is long, the processing heat generated cannot be sufficiently removed, which may adversely affect the flatness of the workpiece.

The present invention was made in consideration of these points, and aims to provide a method for polishing a workpiece that can polish the workpiece flat.

The method for polishing a workpiece according to one aspect of the present invention is characterized by comprising a polishing step in which a polishing liquid is supplied to a workpiece held on a holding table having an internal flow path through which a medium for temperature adjustment is supplied, while the workpiece is polished with a polishing pad; a measurement step in which at least one of the temperature of the holding table, the temperature of the polishing pad, the temperature of the drained medium, the amount of polishing of the workpiece, and the temperature of the drained polishing liquid is measured; and a medium adjustment step in which at least one of the temperature or flow rate of the medium is changed depending on the results of the measurement step.

The workpiece polishing method of the present invention allows the amount of heat that can be removed to be adjusted, so the workpiece can be polished flat even in a work environment where heat is likely to accumulate.

1 is a diagram for explaining a configuration of a polishing apparatus according to an embodiment of the present invention; FIG. 2 is a diagram showing an oxide film forming step. FIG. 2 illustrates a planarization step. FIG. 13 is a diagram showing a substrate bonding step. FIG. 13 is a diagram showing the relationship between the measured temperature and the supply temperature of a temperature adjustment medium. FIG. 13 is a diagram showing the relationship between the measured temperature and the supply flow rate of the temperature adjustment medium. 13 is a diagram showing the relationship between the variation in polishing amount and the supply temperature of a temperature adjustment medium. FIG. 13 is a diagram showing the relationship between the variation in polishing amount and the supply flow rate of a temperature adjustment medium. FIG. FIG. 13 is a diagram showing the shape of a thermally expanded porous plate.

The polishing apparatus and method according to the present embodiment will be described below with reference to the attached drawings. FIG. 1 shows the configuration of the polishing apparatus. The polishing apparatus 1 shown in FIG. 1 is a polishing apparatus that performs polishing using chemicals (hereinafter referred to as wet polishing), such as CMP (Chemical Mechanical Polishing), and is an example of a processing apparatus that polishes a workpiece W.

However, the polishing device according to this embodiment is not limited to a device dedicated to polishing as shown in FIG. 1. The polishing device according to this embodiment may be incorporated into, for example, a fully automatic type processing device that performs a series of processes such as grinding, polishing, and cleaning fully automatically.

The workpiece W to be polished is not particularly limited, but may be, for example, a disk-shaped as-sliced wafer cut from a cylindrical ingot of silicon or the like. The workpiece W is not limited to an as-sliced wafer before devices are formed, but may also be a device wafer after devices are formed. The material of the wafer is not limited to silicon. For example, it may be another semiconductor substrate such as gallium arsenide, or an inorganic material substrate such as ceramic, glass, or sapphire.

The polishing using the polishing apparatus 1 is not particularly limited, but is used, for example, in planarization processing in the wafer manufacturing process or the front-end process of semiconductor manufacturing. In addition to planarization processing, polishing using the polishing apparatus 1 may also be used for stress relief after grinding the back surface of the wafer, mirror finishing, and other applications.

The polishing liquid (slurry), which is the chemical used for polishing, is not particularly limited, but may be, for example, an alkaline or acidic aqueous solution containing abrasive grains. The polishing liquid may contain abrasive grains such as green carborundum, diamond, alumina, cerium oxide, or CBN (cubic boron nitride). Alkaline polishing liquids may be used for polishing silicon wafers, and acidic polishing liquids may be used for polishing inorganic material wafers.

As shown in FIG. 1, the polishing apparatus 1 includes a polishing mechanism 10 having a polishing pad 12, a holding table 20 that holds a workpiece W, a rotation mechanism 30 that rotates the holding table 20, a rocking mechanism 40 that rocks the workpiece W relative to the polishing pad 12, and a polishing liquid supply source 60 that supplies polishing liquid between the polishing pad 12 and the workpiece W.

As shown in FIG. 1, the polishing apparatus 1 also includes a temperature adjustment medium supplying device 70 that supplies a medium for adjusting the temperature (hereinafter referred to as the temperature adjustment medium) to the holding table 20, a recovery section 80 that recovers the polishing liquid and waste liquid of the temperature adjustment medium, and a group of sensors that detect various data (temperature sensor 91, temperature sensor 92, temperature sensor 93, thickness measurement unit 94).

The polishing apparatus 1 further includes a control unit (not shown) that controls each part of the apparatus. The control unit is composed of a processor that executes various processes, a memory, etc. The memory is composed of one or more storage media such as a ROM (Read Only Memory) or a RAM (Random Access Memory) depending on the application.

The polishing mechanism 10 is equipped with a spindle unit 11 having a spindle shaft 14 that can rotate freely around the Z axis. The direction of the Z axis is perpendicular to the surface on which the base 50 is placed, and is vertical if the base 50 is placed on a horizontal surface. The polishing pad 12 is attached to a platen 13 provided at the lower end of the spindle shaft 14. When the spindle shaft 14 rotates around the Z axis, the polishing pad 12 attached to the platen 13 rotates.

The spindle unit 11 is fixed, for example, via a flange portion (not shown) to a housing (not shown) that surrounds the spindle unit 11. The polishing apparatus 1 further includes a lifting mechanism (not shown) that moves up and down in the Z-axis direction along a column erected on the base 50, and the polishing mechanism 10 is fixed to the lifting table of the lifting mechanism via the housing described above. In the polishing apparatus 1, the lifting table moves up and down, making it possible to adjust the position of the polishing pad 12 in the Z-axis direction relative to the workpiece W.

The polishing mechanism 10 is further provided with a through hole 15, which passes through the spindle unit 11, the spindle shaft 14, the platen 13, and the polishing pad 12. A thickness measuring unit 94 is disposed at the upper opening of the through hole 15. Furthermore, a polishing liquid supply source 60 that supplies polishing liquid is connected to the through hole 15. The polishing liquid supplied from the polishing liquid supply source 60 is supplied between the polishing pad 12 and the workpiece W through the through hole 15.

The control unit controls the movement of the polishing mechanism 10 using the lifting mechanism, the rotation of the polishing pad 12 by the spindle unit 11, the supply of polishing liquid from the polishing liquid supply source 60, etc. The control unit performs these control operations, allowing the polishing mechanism 10 to polish the workpiece W.

The holding table 20 is a chuck table and includes a porous plate 21 and a frame 22. In the holding table 20, the porous plate 21 is fitted into a recess formed in the upper surface of the frame 22, so that the upper surface of the porous plate 21 and the upper surface of the frame 22 are flush with each other.

The porous plate 21 is made of a porous material such as porous ceramic. Fine pores are formed throughout the porous plate 21. More specifically, the porous plate 21 has, for example, a disk shape, and is configured as a dense body with a higher pore density in the peripheral portion than in the central portion. The frame body 22 is formed with a suction path that connects the upper surface of the recess in which the porous plate 21 is fitted to a suction source (not shown).

The frame 22 further includes a flow path 23 for a temperature adjustment medium for adjusting the temperature of the holding table 20. The temperature adjustment medium is typically a liquid. The flow path 23 is a water channel that guides the temperature adjustment medium supplied to the frame 22 from the temperature adjustment medium supply device 70 via the flow rate controller 71 through the frame 22 to the collection section 80.

The control unit controls the suction operation of the suction source (not shown) to generate negative pressure in the porous plate 21. This allows the holding table 20 to suction and hold the workpiece W. The control unit also controls the temperature adjustment medium supply device 70 and the flow rate controller 71 to supply the temperature adjustment medium to the flow path 23. This allows the temperature adjustment medium flowing through the holding table 20 to remove (remove) heat from the holding table 20, which has been heated by frictional heat generated between the polishing pad 12 and the workpiece W, and cool it. As a result, the polishing apparatus 1 can suppress a rise in temperature of the holding table 20, and therefore of the workpiece W held on the holding table 20, and further, of the polishing pad 12 in contact with the workpiece W.

The function of the temperature adjustment medium is not limited to cooling the holding table 20. When the temperature of the temperature adjustment medium is higher than that of the holding table 20, the temperature adjustment medium acts to warm the holding table 20. The temperature adjustment medium may act as at least one of a cooling medium and a heating medium. More preferably, the temperature adjustment medium may function as at least a cooling medium, and may also function as a heating medium. Heating may improve the polishing speed.

The rotation mechanism 30 rotatably connects the holding table 20 and the rocking mechanism 40. The rotation mechanism 30 includes, for example, a rotating shaft 31 connected to the holding table 20, a bearing (not shown) that rotatably supports the rotating shaft 31 on the rocking mechanism 40, and a motor (not shown) that applies torque to the rotating shaft 31.

The control unit controls the driving of a motor (not shown) of the rotation mechanism 30 to rotate the holding table 20. This allows the workpiece W to be polished using both the rotation of the holding table 20 and the rotation of the polishing pad 12.

The rocking mechanism 40 includes a table 41 that supports the holding table 20 via the rotation mechanism 30, a ball screw 42 that extends in the rocking direction on the base 50, a guide rail (not shown), and a motor 43 connected to one end of the ball screw 42. The table 41 is fixed, for example, to a nut (not shown) of the ball screw 42.

The control unit controls the driving of the motor 43 to oscillate the holding table 20. As a result, the workpiece W held on the holding table 20 oscillates relative to the polishing pad 12, so that the polishing device 1 can polish the entire workpiece while adjusting the polishing area within the workpiece W and the polishing conditions by the oscillation.

In the polishing apparatus 1, an example has been shown in which the rocking mechanism 40 rocks the workpiece W via the holding table 20, but the rocking mechanism may operate so that the workpiece W rocks relative to the polishing pad 12. Instead of rocking the holding table 20 or the workpiece W, the rocking mechanism may rock the polishing pad 12, or may rock the spindle unit 11 to rock the polishing pad 12.

The temperature adjustment medium supplying device 70 supplies the temperature adjustment medium to the holding table 20 via a flow controller 71. The flow rate of the temperature adjustment medium supplied by the temperature adjustment medium supplying device 70 is adjusted by the flow controller 71 under the control of the control unit, for example. Furthermore, the temperature of the temperature adjustment medium supplied by the temperature adjustment medium supplying device 70 may be adjusted by the control performed by the control unit. The temperature of the temperature adjustment medium supplied by the temperature adjustment medium supplying device 70 may be adjusted by the temperature adjustment medium supplying device 70 itself under the control of the control unit, for example, and the temperature-adjusted temperature adjustment medium may be supplied to the holding table 20 via the flow controller 71.

The control unit controls the temperature adjustment medium supply device 70 and the flow rate controller 71. More specifically, the control unit controls the temperature adjustment medium supply device 70 and the flow rate controller 71 to adjust at least one of the temperature and flow rate of the temperature adjustment medium. This adjusts the amount of heat that can be removed by the temperature adjustment medium supplied to the holding table 20, so that the polishing apparatus 1 can adjust the temperature of the holding table 20 to within a temperature range suitable for polishing the workpiece W.

The recovery section 80 recovers waste liquid generated in the polishing apparatus 1. In the polishing apparatus 1, two types of waste liquid are generated: polishing liquid and temperature adjustment medium. Although the specific method is not particularly limited, it is desirable for the recovery section 80 to recover these separately or through separate paths. By recovering them separately or through separate paths, the temperature sensor 91 can easily measure the temperature of the polishing liquid waste and the temperature of the temperature adjustment medium waste. For example, the temperature adjustment medium waste may be recovered via the flow path 23, and the polishing liquid waste may be recovered via the suction path.

The temperature sensor 91 is, for example, a contact-type temperature sensor using a thermocouple, and measures the temperature of the drainage liquid. The temperature sensor 91 may also be another contact-type temperature sensor, such as a thermistor. The measurement result by the temperature sensor 91 is output to the control unit. The control unit may use the measurement result by the temperature sensor 91 to control the temperature adjustment medium supplied to the holding table 20.

The temperature sensor 92 and the temperature sensor 93 are, for example, non-contact radiation temperature sensors. The temperature sensor 92 measures the temperature of the holding table 20, and the temperature sensor 93 measures the temperature of the polishing pad 12. The measurement results by the temperature sensors 92 and 93 are output to the control unit. The control unit may control the temperature adjustment medium supplied to the holding table 20 using the measurement results by at least one of the temperature sensors 92 and 93.

The thickness measurement unit 94 measures the thickness of the workpiece W. The thickness measurement unit 94 may measure the thickness of the entire workpiece W, or may measure the thickness of a specific layer (e.g., an oxide film) within the workpiece W. The thickness measurement unit 94 is installed at the upper end opening of the through hole 15 formed in the polishing mechanism 10. The thickness measurement unit 94 is an optical measurement unit that measures the thickness of the workpiece W using reflected light of inspection light irradiated through the through hole 15. The thickness measurement unit 94 may be, for example, a measurement unit that uses reflectance spectroscopy in which light is irradiated perpendicularly to the workpiece W.

The thickness measurement unit 94 can measure the thickness of the workpiece W at various positions by changing the positional relationship between the polishing mechanism 10 and the workpiece W using the oscillating mechanism 40. The thickness measurement unit 94 may measure the thickness of the central portion and the peripheral portion of the workpiece W, for example. The measurement results by the thickness measurement unit 94 are output to the control unit. The control unit may use the measurement results by the thickness measurement unit 94 to control the temperature adjustment medium supplied to the holding table 20. The control unit may also control each part of the polishing apparatus 1 to measure the thickness at a predetermined time interval using the thickness measurement unit 94, and end polishing when the measured value reaches a predetermined desired thickness, for example.

The method of thickness measurement by the thickness measurement unit 94 is not particularly limited. The arrangement of the thickness measurement unit 94 is also not particularly limited. As shown in FIG. 1, the thickness measurement unit 94 may be arranged directly above the workpiece W and the thickness may be measured using reflectance spectroscopy. The thickness measurement unit 94 may also employ other optical measurement methods such as ellipsometry, which measures the thickness by irradiating the workpiece W with light from an oblique angle. The thickness measurement unit 94 may also measure the thickness using a method other than the optical measurement method.

2A to 2C are diagrams for explaining a process in which the polishing apparatus according to the present embodiment is particularly suitable. FIG. 2A is a diagram showing a step of forming a layer of oxide film 103. FIG. 2B shows a step of planarizing the layer of oxide film 103. FIG. 2C shows a step of bonding another substrate 104 onto the planarized layer of oxide film 103.

In the step shown in FIG. 2A, an oxide film 103 is formed on a support substrate 101 on which chips 102 are arranged. This results in the formation of a workpiece covered with the oxide film 103. In the workpiece including the support substrate 101, multiple chips 102, and oxide film 103, the oxide film 103 has irregularities corresponding to the height of the chips 102.

In the step shown in FIG. 2B, the oxide film 103 is polished to flatten the oxide film 103, which has irregularities according to the height of the chip 102. If the flattening process shown in FIG. 2B is insufficient, it may cause problems in subsequent steps, such as the bonding of the substrate 104 in FIG. 2C. Therefore, in the step shown in FIG. 2B, it is required to sufficiently flatten the oxide film 103.

However, as mentioned above, the oxide film 103 has irregularities whose size corresponds to the thickness of the chip 102, so a larger amount of polishing than usual is often required. For example, whereas polishing of about 2-3 μm is usually sufficient, polishing of as much as 10-20 μm may be required to flatten the oxide film 103 that covers the support substrate 101 and chip 102.

In this way, the polishing time required for the planarization of an oxide film is longer than that required for a normal planarization process because the amount of polishing is large. Furthermore, the characteristic of the oxide film itself, which makes it difficult to polish, also contributes to this tendency. Therefore, the planarization of an oxide film is likely to generate heat in excess of the amount of heat that can be removed, and thermal expansion can easily hinder polishing the workpiece to a flat surface. However, with the polishing device 1 described above, by carrying out the polishing method described below, the workpiece can be polished to a sufficiently flat surface even when the oxide film is being flattened. This point will be explained in more detail below.

In the above, the planarization process of an oxide film covering a chip has been given as an example of a process that requires a long polishing time, but the process that requires a long polishing time is not limited to this example. Since polishing an oxide film takes time, the polishing device 1 may be applied to a process of planarizing an oxide film regardless of whether it covers a chip. Furthermore, the polishing device 1 may be applied not only to the planarization process of an oxide film, but also to other processes that require a long polishing time, such as processes for machining multiple workpieces in succession. With the polishing device 1, the workpiece can be polished sufficiently flat even when the polishing time is long.

Figures 3A to 3D are diagrams for explaining the control of the temperature adjustment medium performed by the polishing apparatus according to this embodiment. Figure 3A is a diagram showing the relationship between the measured temperature and the supply temperature of the temperature adjustment medium. Figure 3B is a diagram showing the relationship between the measured temperature and the supply flow rate of the temperature adjustment medium. Figure 3C is a diagram showing the relationship between the variation in the polishing amount and the supply temperature of the temperature adjustment medium. Figure 3D is a diagram showing the relationship between the variation in the polishing amount and the supply flow rate of the temperature adjustment medium. Figure 4 is a diagram showing the shape of the thermally expanded porous plate 21.

The polishing method performed by the polishing apparatus 1 will now be described. The polishing apparatus 1 performs a polishing method that includes a polishing step, a measurement step, and a media adjustment step.

In the polishing step, the control unit controls each part of the polishing device 1, so that the workpiece W held on the holding table 20 is polished with the polishing pad 12 while a polishing liquid is supplied to the workpiece W. A flow path through which a temperature adjustment medium is supplied is formed inside the holding table 20. Therefore, the temperature adjustment medium can remove the processing heat generated in the polishing step according to its temperature and flow rate, thereby cooling the holding table 20.

In addition, in the measurement step, the group of sensors of the polishing apparatus 1 measures at least one of the temperature of the holding table 20, the temperature of the polishing pad 12, the temperature of the drained temperature adjustment medium, the amount of polishing of the workpiece W, and the temperature of the drained polishing liquid. This makes it possible to detect changes in the polishing apparatus 1 related to thermal expansion that prevents the workpiece W from being polished flat.

The temperature of the holding table 20 is measured non-contact by a temperature sensor 92, and the temperature of the polishing pad 12 is measured non-contact by a temperature sensor 93. These temperature sensors measure the temperatures of the components of the polishing apparatus 1 (holding table 20) and the workpiece W non-contact, so that the temperature of the object itself, where thermal expansion occurs, can be measured almost in real time even during the polishing step without adversely affecting the polishing process. Therefore, it is possible to capture without delay any changes in the condition that occur in the polishing apparatus 1 that prevent the workpiece W from being polished flat.

The temperature of the drained temperature adjustment medium and the temperature of the drained polishing liquid are measured by a temperature sensor 91. The temperature sensor 91 comes into contact with the temperature adjustment medium and polishing liquid discharged from the holding table 20 and collected in the collection section 80, and measures their temperatures. This allows for more accurate temperature measurement than the non-contact method.

The thickness measurement unit 94 measures the amount of polishing of the workpiece W. When thermal expansion occurs in the porous plate 21, the central part of the disk expands more than the peripheral part, as shown in FIG. 4. This is because the proportion of pores formed in the porous plate 21 is higher in the central part than in the peripheral part, and the gas in the pores has a higher expansion coefficient than a solid. As the central part of the porous plate 21 expands more, the central part of the workpiece W is also polished more, which deteriorates the flatness of the workpiece W.

The thickness measurement unit 94 measures the thickness at multiple different radial positions by the oscillation mechanism 40 oscillating the workpiece W. The thickness measurement unit 94 measures the thickness of the central and peripheral parts of the workpiece W, for example, and detects the variation in the amount of polishing from the difference between the thicknesses. This makes it possible to detect deterioration in the flatness of the workpiece W more directly than a temperature sensor. Furthermore, by configuring the thickness measurement unit 94 as an optical thickness measurement unit, it is possible to measure only the thickness of a specific layer, such as an oxide film. Therefore, it is possible to measure only the amount of polishing of a specific layer by comparing it with the film thickness immediately after formation.

Furthermore, in the medium adjustment step, the control unit controls the temperature adjustment medium supply device 70 and the flow rate controller 71 to change at least one of the temperature and flow rate of the temperature adjustment medium according to the results of the measurement step. This makes it possible to adjust the amount of heat that can be removed per unit time. In particular, by making adjustments according to the results of the measurement step, it is possible to avoid excessive adjustments to the temperature adjustment medium or adjustments that are more frequent than necessary.

The specific control method in the medium adjustment step is not particularly limited, but for example, at least one of the temperature and flow rate of the temperature adjustment medium may be controlled by the following method. For example, the memory of the control unit stores information on the desired relationship between the measurement results of the sensor group and at least one of the temperature and flow rate of the temperature adjustment medium after adjustment, as shown in Figures 3A to 3D. The control unit may use this information to control the temperature adjustment medium supply device 70 and the flow rate controller 71 according to the measurement results.

Figure 3A shows information indicating a negative correlation between the measured temperature (temperature of the holding table 20, temperature of the polishing pad 12, temperature of the drained temperature adjustment medium, temperature of the drained polishing liquid, etc.) and the supply temperature of the temperature adjustment medium. As the measured temperature increases, the amount of heat to be removed also increases. For this reason, the control unit may control the temperature adjustment medium supply device 70 to lower the temperature of the temperature adjustment medium supplied to the holding table 20 in response to an increase in the measured temperature, as shown in Figure 3A.

Figure 3B shows information indicating a positive correlation between the measured temperature (temperature of the holding table 20, temperature of the polishing pad 12, temperature of the drained temperature adjustment medium, temperature of the drained polishing liquid, etc.) and the flow rate of the temperature adjustment medium supplied. As the measured temperature increases, the amount of heat to be removed also increases. For this reason, the control unit may control the flow rate controller 71 to increase the flow rate of the temperature adjustment medium supplied to the holding table 20 in response to an increase in the measured temperature, as shown in Figure 3B.

Figure 3C shows information indicating a negative correlation between the variation in the amount of polishing and the supply temperature of the temperature adjustment medium. It is estimated that the greater the variation in the amount of polishing, the greater the amount of stored heat, and therefore the amount of heat to be removed also increases. For this reason, as shown in Figure 3C, the control unit may control the temperature adjustment medium supply device 70 to lower the temperature of the temperature adjustment medium supplied to the holding table 20 in response to an increase in the variation in the amount of polishing.

Figure 3D shows information indicating a positive correlation between the variation in the amount of polishing and the flow rate of the temperature adjustment medium supplied. It is estimated that the greater the variation in the amount of polishing, the greater the amount of stored heat, and therefore the amount of heat to be removed also increases. For this reason, the control unit may control the flow rate controller 71 to increase the flow rate of the temperature adjustment medium supplied to the holding table 20 in response to an increase in the variation in the amount of polishing, as shown in Figure 3D.

Note that although Figures 3A to 3D show a linear correlation as a desirable relationship, the correlation indicated by the information stored in the control unit is not limited to a linear relationship and may be a nonlinear relationship. The control unit only needs to store a desirable correlation obtained by measurement, simulation, etc.

Although FIGS. 3A to 3D show desirable relationships between two parameters (measured temperature and supply temperature, measured temperature and supply flow rate, polishing amount variation and supply temperature, polishing amount variation and supply flow rate), desirable relationships between three or more parameters may be stored. The control unit may determine the temperature of the temperature adjustment medium from, for example, two or more measured temperatures (e.g., the temperature of the holding table 20 and the temperature of the drained temperature adjustment medium). Also, the control unit may determine the temperature and flow rate of the temperature adjustment medium from one or more measured temperatures (e.g., the temperature of the drained temperature adjustment medium).

The control unit may also store information on multiple points indicating a desired correlation in table format, and may generate necessary information from such information by interpolation or the like. The control unit may also store information on function forms and parameters indicating a desired correlation.

In the above polishing method, changes caused by processing heat generated in the polishing step are detected by the measurement results in the measurement step, and at least one of temperature control and flow rate control of the temperature adjustment medium is performed according to the measurement results. This allows the heat removal capacity of the polishing device 1 to be appropriately adjusted. Therefore, even if the polishing time is long, the polishing device 1 can prevent or suppress deformation of the holding table 20 due to high temperatures.

The measurement results used in the above-mentioned medium adjustment step may be measurement results obtained from a single measurement, or may be measurement results obtained from multiple measurements. The measurement results obtained from multiple measurements may be results calculated by statistical processing from measurements taken within a specified period, and may be, for example, the average value, median value, mode value, etc.

Although not specifically mentioned above, the above-mentioned media adjustment step may be performed while the polishing step is being carried out. By performing the media adjustment step during the polishing step, there is no need to stop polishing to control the temperature and flow rate of the temperature adjustment medium, and the workpiece can be polished efficiently.

The control unit may periodically perform measurements using the group of sensors, and adjust at least one of the temperature and flow rate of the temperature supply medium using the temperature adjustment medium supply device 70 and the flow rate controller 71 each time depending on the measurement results. By performing adjustments each time a measurement is made, large fluctuations in the temperature of the holding table 20 can be suppressed, so that the desired temperature range can be maintained and the amount of adjustment of the temperature or flow rate of the temperature adjustment medium per time can be kept small.

The control unit may also perform measurements periodically or continuously using the group of sensors, and adjust at least one of the temperature and flow rate of the temperature supply medium using the temperature adjustment medium supply device 70 and the flow rate controller 71 based on a comparison between the measurement results and a threshold value. For example, when the variation in the polishing amount between the central portion and the peripheral portion obtained from the measurement results exceeds a predetermined threshold value, the control unit may adjust at least one of the temperature and flow rate of the temperature supply medium using the temperature adjustment medium supply device 70 and the flow rate controller 71. By separating the timing of measurement and adjustment using the threshold value, it is possible to set short measurement intervals and thoroughly monitor the state of the polishing apparatus 1 while avoiding frequent adjustment of the temperature adjustment medium.

The above-mentioned media adjustment step may also be performed for each workpiece. That is, after the polishing step is performed on a workpiece, the media adjustment step may be performed before the polishing step is performed on the next workpiece. By performing the media adjustment step between polishing steps, even if it takes some time to adjust the temperature and flow rate of the temperature adjustment medium, it is possible to effectively utilize the time required to replace the workpiece, and the workpiece can be polished efficiently.

The control unit may use the group of sensors to perform measurements while a workpiece is being polished, and after polishing of the workpiece is finished and the next workpiece is being prepared, adjust at least one of the temperature and flow rate of the temperature adjustment medium using the measurement results of the previous workpiece. Note that if the measurement target is not a workpiece, the measurement step may also be performed after polishing of a workpiece is finished and the next workpiece is being prepared, that is, between polishing steps.

Furthermore, the control unit may execute a combination of control to perform an adjustment step during the polishing step and control to perform an adjustment step between one polishing step and the next polishing step. For example, if the measurement value by the sensor group falls outside the allowable range represented by the threshold value, the adjustment step may be executed during the polishing step, and at least one of the temperature and flow rate of the temperature adjustment medium may be changed to an optimal state between polishing steps even if it is within the allowable range. This makes it possible to maintain the flatness of the resulting workpiece while avoiding, as much as possible, adjustment of the temperature adjustment medium during polishing operations on the same workpiece.

The embodiments of the present invention are not limited to the above-mentioned embodiments and modifications, and may be modified, substituted, or altered in various ways without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in a different way due to technological advances or derived other technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may be included within the scope of the technical idea of the present invention.

In the above-described embodiment, a suction chuck type table is exemplified as a holding table having a flow path through which a temperature adjustment medium is supplied, but the holding table is not limited to a suction chuck type table and may be an electrostatic chuck type table.

In addition, in the above-described embodiment, a polishing method and a polishing apparatus using wet polishing are exemplified, but the polishing method and the polishing apparatus can also be applied to dry polishing.

As described above, the workpiece polishing method of the present invention can adjust the amount of heat that can be removed per unit time, making it possible to polish the workpiece flat even in a working environment where heat is likely to accumulate, such as when polishing is continued for a long period of time, and is therefore extremely useful as a polishing method used in polishing devices, etc.

1: Polishing apparatus 10: Polishing mechanism 11: Spindle unit 12: Polishing pad 13: Platen 14: Spindle shaft 15: Through hole 20: Holding table 21: Porous plate 22: Frame 23: Flow path 30: Rotation mechanism 40: Swing mechanism 41: Table 42: Ball screw 43: Motor 50: Base 60: Polishing liquid supply source 70: Temperature adjustment medium supply device 71: Flow rate controller 80: Recovery section 91: Temperature sensor 92: Temperature sensor 93: Temperature sensor 94: Thickness measurement unit W: Workpiece

Claims (5)

A method for polishing a workpiece, comprising the steps of:
a polishing step in which a polishing liquid is supplied to a workpiece held on a holding table having an internal flow path through which a medium for temperature adjustment is supplied, while the workpiece is polished with a polishing pad;
a measuring step of measuring at least one of a temperature of the holding table, a temperature of the polishing pad, a temperature of the drained medium, a polishing amount of the workpiece, and a temperature of the drained polishing liquid;
a medium adjusting step of varying at least one of a temperature or a flow rate of the medium in response to a result of the measuring step;
A method for polishing a workpiece, comprising: The medium conditioning step includes:
2. The method for polishing a workpiece according to claim 1, which is carried out during the polishing step. The medium conditioning step includes:
2. The method for polishing a workpiece according to claim 1, wherein the method is carried out after the polishing step is carried out on a workpiece and before the polishing step is carried out on a next workpiece. The workpiece is coated with an oxide film,
2. The method for polishing a workpiece according to claim 1, wherein said polishing step polishes said oxide film. The workpiece is
A support substrate, a plurality of chips arranged on the support substrate, and an oxide film covering the plurality of chips and having projections and recesses corresponding to the height of the chips,
2. The method for polishing a workpiece according to claim 1, wherein the oxide film is planarized in the polishing step.

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