Polishing device and polishing method

Abstract

To provide a polishing device that can improve the uniformity of wafer thickness.SOLUTION: A polishing device has an operation controller 9 that controls the individual pressure of each of pressure chambers. The operation controller 9 controls the pressure within the pressure chamber of a polishing head 1 corresponding to a specific position so as to reduce the difference between a control object thickness value and an average thickness value of the whole substrate.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] As a technique in the manufacturing process of semiconductor devices, chemical mechanical polishing (CMP) is known. A polishing apparatus for performing CMP includes a polishing table that supports a polishing pad and a polishing head for holding a wafer.

[0003] When polishing a wafer using such a polishing apparatus, the wafer is held by the polishing head and pressed against the polishing surface of the polishing pad with a predetermined pressure. At this time, the wafer is brought into sliding contact with the polishing surface by relatively moving the polishing table and the polishing head, and the surface of the wafer is polished.

[0004] Furthermore, a signal corresponding to the film thickness of the wafer is detected by a film thickness sensor, and the film thickness distribution of the wafer is obtained. Based on the film thickness distribution of the wafer, the end point of polishing is determined, or the pressure of a plurality of air bags provided concentrically on the polishing head is controlled. The film thickness sensor rotates together with the polishing table, and the polishing head that holds the wafer also rotates. Therefore, the movement path of the film thickness sensor across the surface of the wafer is different every time the polishing table makes one rotation. Usually, the film thickness distribution of the wafer is calculated as an averaged value in the circumferential direction based on signals obtained from different measurement points on the circumference.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, the required degree of uniformity in film thickness has increased. Therefore, it has become necessary to manage and control the polishing process, taking into account variations in the circumferential direction of the initial film thickness of the wafer due to the characteristics of the film deposition equipment, and variations in the amount of polishing in the circumferential direction caused by polishing (for example, it is effective to improve the uniformity of the wafer film thickness by actively polishing areas where the film is thicker, or by actively polishing areas other than those where the film is thin). In addition, with conventional methods, it can be difficult to keep the difference between the maximum and minimum film thickness on the wafer surface within an acceptable range.

[0007] Therefore, the present invention aims to provide a polishing apparatus and a polishing method that can improve the uniformity of the wafer film thickness. [Means for solving the problem]

[0008] In one embodiment, a polishing apparatus is provided comprising: a polishing table supporting a polishing pad; a polishing head having a plurality of concentrically divided pressure chambers for pressing a substrate against the polishing surface of the polishing pad; a plurality of pressure regulators connected to the plurality of pressure chambers; a film thickness sensor embedded in the polishing table that outputs a signal corresponding to the film thickness of the substrate; and an operation control unit that individually controls the pressure of each of the plurality of pressure chambers through the plurality of pressure regulators. The operation control unit acquires information about a specific position which is a part of the circumference of the substrate, calculates a target film thickness value in the control target region including the specific position and the overall average film thickness value of the substrate, and controls the pressure in the pressure chamber of the polishing head corresponding to the specific position so as to reduce the difference between the target film thickness value and the overall average film thickness value of the substrate.

[0009] In one embodiment, the operation control unit identifies the specific position based on the film thickness of the substrate measured before polishing. In one embodiment, the operation control unit determines the maximum film thickness position where the maximum film thickness value is obtained and the minimum film thickness position where the minimum film thickness value is obtained, based on the film thickness of the substrate measured before polishing, and determines at least one of the maximum film thickness position and the minimum film thickness position as the specific position. In one embodiment, the operation control unit determines a maximum film thickness value and a minimum film thickness value based on the film thickness of the substrate measured before polishing, calculates the difference between the overall average film thickness value of the substrate and the maximum film thickness value, and the difference between the overall average film thickness value of the substrate and the minimum film thickness value, and determines the position on the substrate where the film thickness value with the largest difference is obtained as the specific position.

[0010] In one embodiment, the controlled film thickness value corresponds to at least one of the maximum film thickness value and minimum film thickness value determined based on the film thickness of the substrate measured before polishing. In one embodiment, the controlled film thickness value is the average value of a plurality of film thickness values ​​within the controlled region. In one embodiment, the operation control unit measures the film thickness of the controlled area, including the specific position, during polishing based on a signal output from the film thickness sensor, and controls the pressure in the pressure chamber of the polishing head corresponding to the specific position based on the measured film thickness.

[0011] In one embodiment, the operation control unit divides the plurality of pressing regions on the substrate, which are divided according to the plurality of pressure chambers, into a specific pressing region including the controlled region and other pressing regions excluding the specific pressing region, calculates the average film thickness value in the other pressing regions based on the film thickness of the substrate, and controls the pressure in the pressure chambers corresponding to the other pressing regions so as to reduce the difference between the average film thickness value of the other pressing regions and the average film thickness value of the entire substrate. In one embodiment, the operation control unit acquires information about a reference position which is a part of the circumference of a reference substrate different from the substrate, and during polishing of the reference substrate, the film thickness sensor detects a physical quantity corresponding to the film thickness of the region on the substrate including the reference position, acquires a plurality of data corresponding to the film thickness of the reference substrate based on a plurality of signals sent from the film thickness sensor, and associates each of the plurality of data with the film thickness of the reference substrate at the time each of the plurality of data was acquired. In one embodiment, the operation control unit determines the reference position based on the film thickness of the reference substrate measured before polishing.

[0012] In one embodiment, the operation control unit controls at least one of the rotational speed of the polishing head and the rotational speed of the polishing table so that the film thickness sensor crosses the controlled area. In one embodiment, the operation control unit determines the relative angle between the reference position and the polishing head based on the relationship between the reference position of the circumferential angle of the substrate and the rotation angle of the polishing head, and controls at least one of the rotation speed of the polishing head and the rotation speed of the polishing table based on the determined relative angle.

[0013] In one embodiment, a polishing method is provided in which a substrate is pressed against the polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers divided in a concentric circle. The polishing method acquires information about a specific position which is a part of the circumference of the substrate, calculates a controlled target film thickness value in a controlled target area including the specific position and the overall average film thickness value of the substrate, and controls the pressure in the pressure chamber of the polishing head corresponding to the specific position so as to reduce the difference between the controlled target film thickness value and the overall average film thickness value of the substrate.

[0014] In one embodiment, the specific position is determined based on the film thickness of the substrate measured before polishing. In one embodiment, based on the film thickness of the substrate measured before polishing, the maximum film thickness position where the maximum film thickness value is obtained and the minimum film thickness position where the minimum film thickness value is obtained are determined, and at least one of the maximum film thickness position and the minimum film thickness position is determined to be the specific position. In one embodiment, the maximum film thickness value and the minimum film thickness value are determined based on the film thickness of the substrate measured before polishing, the difference between the overall average film thickness value of the substrate and the maximum film thickness value, and the difference between the overall average film thickness value of the substrate and the minimum film thickness value are calculated, and the position on the substrate where the film thickness value with the largest difference is obtained is determined as the specific position.

[0015] In one embodiment, the controlled film thickness value corresponds to at least one of the maximum film thickness value and minimum film thickness value determined based on the film thickness of the substrate measured before polishing. In one embodiment, the controlled film thickness value is the average value of a plurality of film thickness values ​​within the controlled region. In one embodiment, the film thickness of the controlled region including the specific position during polishing is measured based on the output signal of the film thickness sensor, and the pressure in the pressure chamber of the polishing head corresponding to the specific position is controlled based on the measured film thickness.

[0016] In one embodiment, the multiple pressing regions on the substrate, which are divided according to the multiple pressure chambers, are divided into a specific pressing region including the controlled region and other pressing regions excluding the specific pressing region. Based on the film thickness of the substrate, the average film thickness value in the other pressing regions is calculated, and the pressure in the pressure chambers corresponding to the other pressing regions is controlled so as to reduce the difference between the average film thickness value of the other pressing regions and the average film thickness value of the entire substrate. In one embodiment, information is obtained regarding a reference position which is a part of the circumference of a reference substrate different from the substrate. During polishing of the reference substrate, the film thickness sensor detects a physical quantity corresponding to the film thickness of the region on the substrate including the reference position. Based on a plurality of signals sent from the film thickness sensor, a plurality of data corresponding to the film thickness of the reference substrate is obtained, and each of the plurality of data is associated with the film thickness of the reference substrate at the time each of the plurality of data was obtained. In one embodiment, the reference position is determined based on the film thickness of the reference substrate measured before polishing.

[0017] In one embodiment, the rotation speed of the polishing head and the rotation speed of the polishing table are controlled by the rotation of the polishing table supporting the polishing pad so that the film thickness sensor crosses the controlled area. In one embodiment, the relative angle between the reference position and the polishing head is determined based on the relationship between the reference position of the circumferential angle of the substrate and the rotation angle of the polishing head, and at least one of the rotation speed of the polishing head and the rotation speed of the polishing table is controlled based on the determined relative angle.

[0018] In one embodiment, a polishing apparatus is provided comprising: a polishing table that supports a polishing pad; a polishing head having a plurality of concentrically divided pressure chambers for pressing a substrate against the polishing surface of the polishing pad; a plurality of pressure regulators connected to the plurality of pressure chambers; a film thickness sensor embedded in the polishing table that outputs a signal corresponding to the film thickness of the substrate; and an operation control unit that individually controls the pressure of each of the plurality of pressure chambers through the plurality of pressure regulators. The operation control unit uses the film thickness sensor to identify a maximum film thickness value and a minimum film thickness value from the film thickness of the substrate obtained during polishing of the substrate, and identifies at least one of the pressure chambers: a pressure chamber corresponding to the position of the substrate where the maximum film thickness value was detected and a pressure chamber corresponding to the position of the substrate where the minimum film thickness value was detected. When controlling the pressure of the pressure chamber related to the maximum film thickness value, the operation control unit controls the pressure of the pressure chamber related to the maximum film thickness value so that the average film thickness value of the substrate corresponding to the pressure chamber related to the maximum film thickness value is lower than the overall average film thickness value of the substrate. When controlling the pressure of the pressure chamber related to the minimum film thickness value, the operation control unit controls the pressure of the pressure chamber related to the minimum film thickness value so that the average film thickness value of the substrate corresponding to the pressure chamber related to the minimum film thickness value is higher than the overall average film thickness value of the substrate.

[0019] In one aspect, during the polishing of the substrate, the operation control unit identifies the maximum film thickness value and the minimum film thickness value based on the film thickness of the substrate obtained at regular time intervals. In one aspect, the operation control unit calculates the polishing rate during polishing from the film thickness of the substrate acquired by the film thickness sensor, and based on the polishing rate, calculates the change amount of the film thickness of the substrate between the acquisition time when the film thickness of the substrate is acquired by the film thickness sensor at each measurement point of the substrate and the reference time. Using the change amount as a correction value, the operation control unit corrects the film thickness of the substrate obtained during the polishing of the substrate at the time interval, and identifies the maximum film thickness value and the minimum film thickness value based on the corrected film thickness of the substrate.

[0020] In one aspect, when the pressure chamber related to the maximum film thickness value and the pressure chamber related to the minimum film thickness value are the same pressure chamber, the operation control unit determines in advance by recipe setting whether to control the pressure of the pressure chamber related to the maximum film thickness value so that the average film thickness value of the substrate corresponding to the pressure chamber related to the maximum film thickness value is lower than the overall average film thickness value of the substrate, or to control the pressure of the pressure chamber related to the minimum film thickness value so that the average film thickness value of the substrate corresponding to the pressure chamber related to the minimum film thickness value is higher than the overall average film thickness value of the substrate. In one aspect, when the pressure chamber related to the maximum film thickness value and the pressure chamber related to the minimum film thickness value are the same pressure chamber, the operation control unit compares the first difference between the maximum film thickness value and the overall average film thickness value of the substrate with the second difference between the minimum film thickness value and the overall average film thickness value of the substrate. When the first difference is greater than the second difference, the operation control unit controls the pressure of the pressure chamber related to the maximum film thickness value so that the average film thickness value of the substrate corresponding to the pressure chamber related to the maximum film thickness value is lower than the overall average film thickness value of the substrate. When the second difference is greater than the first difference, the operation control unit controls the pressure of the pressure chamber related to the minimum film thickness value so that the average film thickness value of the substrate corresponding to the pressure chamber related to the minimum film thickness value is higher than the overall average film thickness value of the substrate. In one aspect, when the pressure chambers related to the maximum film thickness value and the pressure chambers related to the minimum film thickness value are the same pressure chamber, the operation control unit compares a first difference between the maximum film thickness value and the average film thickness value in the pressing region corresponding to the maximum film thickness value, and a second difference between the minimum film thickness value and the average film thickness value in the pressing region corresponding to the minimum film thickness value. When the first difference is greater than the second difference, the pressure of the pressure chamber related to the maximum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber related to the maximum film thickness value is lower than the overall average film thickness value of the substrate. When the second difference is greater than the first difference, the pressure of the pressure chamber related to the minimum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber related to the minimum film thickness value is higher than the overall average film thickness value of the substrate.

[0021] In one aspect, a polishing method is provided in which a substrate is pressed against a polishing surface of a polishing pad by a polishing head having a plurality of concentrically divided pressure chambers. From the film thickness of the substrate obtained during polishing of the substrate, a maximum film thickness value and a minimum film thickness value are specified, and at least one of the pressure chamber corresponding to the position of the substrate where the maximum film thickness value is detected and the pressure chamber corresponding to the position of the substrate where the minimum film thickness value is detected is specified. When controlling the pressure of the pressure chamber related to the maximum film thickness value, the pressure of the pressure chamber related to the maximum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber related to the maximum film thickness value is lower than the overall average film thickness value of the substrate. When controlling the pressure of the pressure chamber related to the minimum film thickness value, the pressure of the pressure chamber related to the minimum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber related to the minimum film thickness value is higher than the overall average film thickness value of the substrate.

[0022] In one aspect, during polishing of the substrate, the maximum film thickness value and the minimum film thickness value are specified based on the film thickness of the substrate obtained at regular time intervals. In one embodiment, the polishing speed during polishing is calculated from the film thickness of the substrate, the amount of change in the film thickness of the substrate between the acquisition time and the reference time at each measurement point of the substrate is calculated based on the polishing speed, the amount of change is used as a correction value to correct the film thickness of the substrate obtained during polishing of the substrate at the time interval, and the maximum film thickness value and the minimum film thickness value are determined based on the corrected film thickness of the substrate.

[0023] In one embodiment, when the pressure chamber associated with the maximum film thickness and the pressure chamber associated with the minimum film thickness are the same pressure chamber, it is predetermined by recipe settings whether to control the pressure in the pressure chamber associated with the maximum film thickness so that the average film thickness of the substrate corresponding to the pressure chamber associated with the maximum film thickness is lower than the overall average film thickness of the substrate, or to control the pressure in the pressure chamber associated with the minimum film thickness so that the average film thickness of the substrate corresponding to the pressure chamber associated with the minimum film thickness is higher than the overall average film thickness of the substrate. In one embodiment, when the pressure chamber associated with the maximum film thickness and the pressure chamber associated with the minimum film thickness are the same pressure chamber, a first difference between the maximum film thickness and the overall average film thickness of the substrate is compared with a second difference between the minimum film thickness and the overall average film thickness of the substrate. If the first difference is greater than the second difference, the pressure in the pressure chamber associated with the maximum film thickness is controlled so that the average film thickness of the substrate corresponding to the pressure chamber associated with the maximum film thickness exceeds the overall average film thickness of the substrate. If the second difference is greater than the first difference, the pressure in the pressure chamber associated with the minimum film thickness is controlled so that the average film thickness of the substrate corresponding to the pressure chamber associated with the minimum film thickness exceeds the overall average film thickness of the substrate. In one embodiment, when the pressure chamber associated with the maximum film thickness and the pressure chamber associated with the minimum film thickness are the same pressure chamber, a first difference between the maximum film thickness and the average film thickness in the pressing region corresponding to the maximum film thickness is compared with a second difference between the minimum film thickness and the average film thickness in the pressing region corresponding to the minimum film thickness. If the first difference is greater than the second difference, the pressure in the pressure chamber associated with the maximum film thickness is controlled so that the average film thickness of the substrate corresponding to the pressure chamber associated with the maximum film thickness is lower than the overall average film thickness of the substrate. If the second difference is greater than the first difference, the pressure in the pressure chamber associated with the minimum film thickness is controlled so that the average film thickness of the substrate corresponding to the pressure chamber associated with the minimum film thickness is higher than the overall average film thickness of the substrate. [Effects of the Invention]

[0024] By controlling the pressure in the pressure chamber of the polishing head corresponding to a control target area that includes a specific position for planarizing the wafer's film thickness, the uniformity of the wafer's film thickness can be improved. [Brief explanation of the drawing]

[0025] [Figure 1] This is a schematic diagram showing one embodiment of a polishing apparatus. [Figure 2] This is a cross-sectional view of the polishing head. [Figure 3] This figure shows an example of a spectrum generated by the motion control unit. [Figure 4] This figure shows an example of a process for associating a reference spectrum with a corresponding film thickness. [Figure 5] This figure shows an example of the process for polishing a wafer to be polished. [Figure 6] This diagram shows a wafer divided into multiple pressing regions. [Figure 7] This is a diagram showing a notch detection device. [Figure 8] Figures 8(a) and 8(b) show the movement paths of the film thickness sensor across the surface of the wafer. [Figure 9]Figures 9(a) and 9(b) are diagrams illustrating the effects of the polishing process according to this embodiment. [Figure 10] This diagram shows the pressure control flow within the pressure chamber by the operation control unit. [Figure 11] This figure illustrates the effects of the polishing process according to another embodiment. [Figure 12] This diagram shows the flow of the motion control unit correcting the film thickness value. [Modes for carrying out the invention]

[0026] Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is a schematic diagram showing one embodiment of a polishing apparatus. As shown in Figure 1, the polishing apparatus comprises a polishing table 3 that supports a polishing pad 2, a polishing head 1 that presses a wafer W (such as a substrate) having a film onto the polishing pad 2, a table motor 6 that rotates the polishing table 3, a polishing liquid supply nozzle 5 for supplying a polishing liquid such as slurry onto the polishing pad 2, a film thickness sensor 40 (in this embodiment, an optical film thickness sensor 40) for measuring the film thickness of the wafer W, and an operation control unit 9 for controlling the operation of the polishing apparatus. The upper surface of the polishing pad 2 constitutes a polishing surface 2a for polishing the wafer W.

[0027] The polishing head 1 is connected to the head shaft 10, which is connected to a polishing head motor (not shown) via a connecting means such as a belt. The polishing head motor rotates the polishing head 1 together with the head shaft 10 in the direction indicated by the arrow. The polishing table 3 is connected to the table motor 6, which is configured to rotate the polishing table 3 and the polishing pad 2 in the direction indicated by the arrow.

[0028] The wafer W is polished as follows: While the polishing table 3 and polishing head 1 are rotated in the direction indicated by the arrows in Figure 1, polishing fluid is supplied from the polishing fluid supply nozzle 5 to the polishing surface 2a of the polishing pad 2 on the polishing table 3. The wafer W is rotated by the polishing head 1 around the head shaft 10, and while the polishing fluid is present on the polishing pad 2, the wafer W is pressed against the polishing surface 2a of the polishing pad 2 by the polishing head 1. The polishing table 3 rotates around its center CP. The surface of the wafer W is polished by the chemical action of the polishing fluid and the mechanical action of the abrasive grains contained in the polishing fluid or the polishing pad 2.

[0029] The operation control unit 9 is comprised of at least one computer. The operation control unit 9 includes a storage device 9a in which a program is stored, and an arithmetic unit 9b that performs calculations according to the instructions contained in the program. The arithmetic unit 9b includes a CPU (Central Processing Unit) or GPU (Graphics Processing Unit), etc., that performs calculations according to the instructions contained in the program stored in the storage device 9a. The storage device 9a includes main memory (e.g., random access memory) accessible by the arithmetic unit 9b, and auxiliary storage (e.g., a hard disk drive or solid-state drive) that stores data and programs.

[0030] The motion control unit 9 is electrically connected to the film thickness sensor 40. In this embodiment, the film thickness sensor 40 directs light onto the surface of the wafer W, detects the reflected light from the wafer W, and outputs a signal corresponding to the film thickness of the wafer W to the motion control unit 9. The motion control unit 9 measures the film thickness of the wafer W based on the signal sent from the film thickness sensor 40 (more specifically, the intensity measurement data of the reflected light from the wafer W).

[0031] In this embodiment, the film thickness sensor 40 is an optical film thickness sensor, but any other film thickness sensor may be used as long as the operation control unit 9 can measure the film thickness of the wafer W. In other words, the film thickness sensor 40 is a sensor that detects a physical quantity related to the film thickness of the wafer W. For example, the film thickness sensor 40 may be an eddy current sensor. The eddy current sensor generates eddy currents by passing a magnetic flux through the conductive film of the wafer W using its sensor coil, thereby detecting eddy currents corresponding to the film thickness of the wafer W and outputting an eddy current signal. The operation control unit 9 measures the film thickness of the wafer W based on this eddy current signal.

[0032] In this embodiment, the film thickness sensor 40 includes a light source 44 that emits light, a spectrometer 47, and an optical sensor head 7 connected to the light source 44 and the spectrometer 47. The optical sensor head 7, the light source 44, and the spectrometer 47 are mounted on the polishing table 3 and rotate together with the polishing table 3 and the polishing pad 2. The position of the optical sensor head 7 is such that it crosses the surface of the wafer W on the polishing pad 2 each time the polishing table 3 and the polishing pad 2 complete one rotation.

[0033] The memory device 9a stores a program for generating a spectrum and detecting the film thickness of the wafer W, which will be described later. Light emitted from the light source 44 is transmitted to the optical sensor head 7 and guided from the optical sensor head 7 to the surface of the wafer W. The light is reflected from the surface of the wafer W, and the reflected light from the surface of the wafer W is received by the optical sensor head 7 and sent to the spectrometer 47. The spectrometer 47 decomposes the reflected light according to its wavelength. In this way, the film thickness sensor 40 detects the intensity of the reflected light at each wavelength and sends the reflected light intensity measurement data to the operation control unit 9.

[0034] Figure 2 is a cross-sectional view of the polishing head. As shown in Figure 2, the polishing head 1 includes an elastic membrane 65 for pressing the wafer W against the polishing surface 2a of the polishing pad 2, a head body 21 for holding the elastic membrane 65, an annular drive ring 62 positioned below the head body 21, and an annular retainer ring 60 fixed to the lower surface of the drive ring 62.

[0035] The elastic membrane 65 is attached to the lower part of the head body 21. The head body 21 is fixed to the end of the head shaft 10, and the head body 21, elastic membrane 65, drive ring 62, and retainer ring 60 are configured to rotate together as the head shaft 10 rotates. The retainer ring 60 and drive ring 62 are configured to move up and down relative to the head body 21. The head body 21 is made of a resin such as engineering plastic (e.g., PEEK).

[0036] The lower surface of the elastic film 65 constitutes a substrate pressing surface 65a that presses the wafer W against the polishing surface 2a of the polishing pad 2. The retainer ring 60 is positioned to surround the substrate pressing surface 65a, and the wafer W is surrounded by the retainer ring 60. Four pressure chambers 70, 71, 72, and 73 are provided between the elastic film 65 and the head body 21.

[0037] Pressure chamber 70 is a circular central pressure chamber located in the center, pressure chamber 73 is an annular edge pressure chamber located on the outermost periphery, and pressure chambers 71 and 72 are intermediate pressure chambers located between pressure chamber 70 and pressure chamber 73, respectively.

[0038] The pressure chambers 70, 71, 72, and 73 are formed by the elastic membrane 65 and the head body 21. The central pressure chamber 70 is circular, while the other pressure chambers 71, 72, and 73 are annular. These pressure chambers 70, 71, 72, and 73 are arranged (divided) in a concentric pattern. In this embodiment, the elastic membrane 65 forms four pressure chambers 70 to 73, but the number of pressure chambers described above is illustrative and may be changed as appropriate.

[0039] Pressure chambers 70, 71, 72, and 73 are connected to gas transfer lines F1, F2, F3, and F4, respectively. One end of gas transfer lines F1, F2, F3, and F4 is connected to a compressed gas supply source (not shown) provided as a utility in the factory where the polishing equipment is installed. Compressed gas, such as compressed air, is supplied to pressure chambers 70, 71, 72, and 73, respectively, through gas transfer lines F1, F2, F3, and F4. When compressed gas is supplied to pressure chambers 70 to 73, the elastic membrane 65 expands, and the compressed gas in pressure chambers 70 to 73 presses the wafer W against the polishing surface 2a of the polishing pad 2 via the elastic membrane 65. Pressure chambers 70 to 73 function as actuators for pressing the wafer W against the polishing surface 2a of the polishing pad 2.

[0040] The retainer ring 60 is an annular member positioned around the elastic film 65 and in contact with the polishing surface 2a of the polishing pad 2. The retainer ring 60 is positioned to surround the peripheral edge of the wafer W, preventing the wafer W from flying out of the polishing head 1 during polishing.

[0041] The upper part of the drive ring 62 is connected to an annular retainer ring pressing device 80. The retainer ring pressing device 80 applies a downward load to the entire upper surface 60b of the retainer ring 60 via the drive ring 62, thereby pressing the lower surface 60a of the retainer ring 60 against the polishing surface 2a of the polishing pad 2.

[0042] The retainer ring pressing device 80 comprises an annular piston 81 fixed to the upper part of the drive ring 62 and an annular rolling diaphragm 82 connected to the upper surface of the piston 81. A retainer ring pressure chamber 83 is formed inside the rolling diaphragm 82. This retainer ring pressure chamber 83 is connected to the compressed gas supply source via a gas transfer line F5. The compressed gas is supplied into the retainer ring pressure chamber 83 through the gas transfer line F5.

[0043] When compressed gas is supplied to the retainer ring pressure chamber 83 from the compressed gas supply source described above, the rolling diaphragm 82 pushes the piston 81 downward, the piston 81 pushes the drive ring 62 downward, and the drive ring 62 further pushes the entire retainer ring 60 downward. In this way, the retainer ring pressing device 80 presses the lower surface 60a of the retainer ring 60 against the polishing surface 2a of the polishing pad 2. The drive ring 62 is detachably connected to the retainer ring pressing device 80.

[0044] Gas transfer lines F1, F2, F3, F4, and F5 extend via rotary joints 25 attached to the head shaft 10. The polishing apparatus further includes pressure regulators R1, R2, R3, R4, and R5, which are provided on the gas transfer lines F1, F2, F3, F4, and F5, respectively. Compressed gas from a compressed gas supply source is supplied independently to pressure chambers 70-73 and retainer ring pressure chamber 83 through pressure regulators R1-R5. Pressure regulators R1-R5 are configured to regulate the pressure of the compressed gas in pressure chambers 70-73 and retainer ring pressure chamber 83. Pressure regulators R1-R5 are connected to the operation control unit 9.

[0045] Pressure regulators R1 to R5 can independently change the internal pressure of pressure chambers 70 to 73 and the retainer ring pressure chamber 83, thereby independently adjusting the pressing force of the wafer W against the polishing surface 2a in four corresponding regions of the wafer W, namely the central portion, the inner intermediate portion, the outer intermediate portion, and the edge portion, and the pressing force of the retainer ring 60 against the polishing pad 2. Gas transfer lines F1, F2, F3, F4, and F5 are also connected to atmospheric release valves (not shown), respectively, making it possible to release the pressure chambers 70 to 73 and the retainer ring pressure chamber 83 to the atmosphere. In this embodiment, the elastic membrane 65 forms four pressure chambers 70 to 73, but in one embodiment, the elastic membrane 65 may form fewer than four or more pressure chambers.

[0046] Figure 3 shows an example of a spectrum generated by the motion control unit. In Figure 3, the horizontal axis represents the wavelength of light reflected from the wafer, and the vertical axis represents the relative reflectance derived from the intensity of the reflected light. Relative reflectance is an index value indicating the intensity of reflected light, and is the ratio of the light intensity to a predetermined reference intensity. By dividing the light intensity (measured intensity) at each wavelength by the predetermined reference intensity, unwanted noise such as variations in intensity inherent to the optical system or light source of the device can be removed from the measured intensity.

[0047] The reference intensity is the light intensity measured in advance for each wavelength, and the relative reflectance is calculated for each wavelength. Specifically, the relative reflectance is obtained by dividing the light intensity (measured intensity) at each wavelength by the corresponding reference intensity.

[0048] The operation control unit 9 is configured to generate a reflected light spectrum from reflected light intensity measurement data. The reflected light spectrum is represented as a line graph (i.e., spectral waveform) showing the relationship between the wavelength and intensity of the reflected light. The intensity of the reflected light can also be expressed as a relative value such as reflectance or relative reflectance.

[0049] In actual polishing, the corrected measured intensity is obtained by subtracting the dark level (background intensity obtained under conditions where light is blocked) from the measured intensity, the corrected reference intensity is obtained by subtracting the dark level from the reference intensity, and then the relative reflectance is obtained by dividing the corrected measured intensity by the corrected reference intensity. Specifically, the relative reflectance R(λ) can be calculated using the following equation (1).

number

[0050] The motion control unit 9 generates a spectrum as shown in Figure 3 from the reflected light intensity measurement data. Furthermore, the motion control unit 9 determines the film thickness of the wafer W from the reflected light spectrum. The reflected light spectrum changes according to the film thickness of the wafer W. Therefore, the motion control unit 9 can determine the film thickness of the wafer W from the reflected light spectrum. Hereinafter, in this specification, the spectrum generated from the reflected light from the wafer W being polished will be referred to as the measured spectrum.

[0051] The motion control unit 9 is configured to determine the film thickness by comparing the measured spectrum (i.e., measurement data) with multiple reference spectra (i.e., reference data). The motion control unit 9 compares the measured spectrum generated during polishing with multiple reference spectra to determine the reference spectrum that is closest in shape to the measured spectrum, and obtains the film thickness associated with this determined reference spectrum. The reference spectrum that is closest in shape to the measured spectrum is the spectrum with the smallest difference in relative reflectance between the reference spectrum and the measured spectrum.

[0052] Multiple reference spectra are obtained in advance by polishing a reference wafer having the same or equivalent initial film thickness as the wafer to be polished (hereinafter, in this specification, wafer W corresponds to the wafer to be polished). The wafer to be polished is a different wafer from the reference wafer and is the wafer on which the film thickness planarization process is performed. The reference wafer is the wafer on which the process of associating the reference spectrum with the corresponding film thickness is performed. Each reference spectrum can be associated with the film thickness at which it was obtained. That is, each reference spectrum was obtained at a different film thickness, and multiple reference spectra correspond to multiple different film thicknesses. Therefore, the current film thickness can be estimated by determining the reference spectrum whose shape is closest to the measured spectrum.

[0053] Figure 4 shows an example of the process of associating a reference spectrum with a corresponding film thickness. First, a reference wafer having the same or equivalent film thickness as wafer W is prepared. The reference wafer is transported to a film thickness measuring instrument 170 (see Figure 1), and the initial film thickness of the reference wafer is measured by the film thickness measuring instrument 170 (see step S101). The film thickness measuring instrument 170 is electrically connected to the operation control unit 9. Based on the film thickness (distribution) of the reference wafer measured by the film thickness measuring instrument 170, the operation control unit 9 determines a reference position for obtaining a reference spectrum over a wide range of film thicknesses (see step S102).

[0054] In this way, the operation control unit 9 obtains information about a specific location, which is a part of the circumference of the reference wafer, from the film thickness measuring instrument 170. The film thickness measuring instrument 170 may be located inside the polishing apparatus. In this case, the film thickness measuring instrument 170 constitutes part of the components of the polishing apparatus. In one embodiment, the film thickness measuring instrument 170 may be located outside the polishing apparatus.

[0055] The reference wafer is polished to obtain reference spectra corresponding to various film thicknesses. Based on the measured film thickness of the reference wafer, the motion control unit 9 determines the maximum film thickness position (i.e., the location where the reference wafer is thickest) where the maximum film thickness value is obtained and the minimum film thickness position (i.e., the location where the reference wafer is thinnest) where the minimum film thickness value is obtained, and determines either the maximum film thickness position or the minimum film thickness position as the reference position. In one embodiment, the motion control unit 9 may determine both the maximum film thickness position and the minimum film thickness position as the reference position.

[0056] In one embodiment, the operation control unit 9 may determine the maximum film thickness value and the minimum film thickness value based on the measured film thickness of the reference wafer, calculate the difference between the overall average film thickness value of the reference wafer and the maximum film thickness value, and the difference between the overall average film thickness value of the reference wafer and the minimum film thickness value, and determine the position on the reference wafer where the film thickness value with the largest difference is obtained as the reference position.

[0057] Next, the reference wafer is polished while a slurry, acting as a polishing liquid, is supplied to the polishing pad 1 (see step S103). During the polishing of the reference wafer, light is shone onto the surface of the reference wafer, and the spectrum of the reflected light from the reference wafer (i.e., the reference spectrum) is obtained (see step S104).

[0058] The motion control unit 9 acquires a reference spectrum at each measurement point on the reference wafer each time the polishing table 3 completes one rotation. The motion control unit 9 controls at least one of the rotation speeds of the polishing head 1 and the polishing table 3 so that the film thickness sensor 40 crosses the reference position on the reference wafer during polishing. With this control, the film thickness sensor 40 detects the reflected light at the reference position, and the motion control unit 9 acquires a reference spectrum that includes the reference position.

[0059] The motion control unit 9 can acquire a reference spectrum over a wide range of film thickness values ​​by acquiring a reference spectrum that includes a reference position. Therefore, the motion control unit 9 can more reliably determine the reference spectrum that is closest in shape to the measurement spectrum generated during polishing, and as a result, it can measure (acquire) the film thickness of wafers W of any thickness.

[0060] A reference spectrum is acquired each time the polishing table 3 rotates. Therefore, multiple reference spectra are acquired during the polishing of the reference wafer. After the polishing of the reference wafer is complete, the reference wafer is again transported to the film thickness measuring instrument 170, where the film thickness of the polished reference wafer (i.e., the final film thickness) is measured (see step S105).

[0061] If the polishing rate of the reference wafer is constant, the film thickness decreases linearly with polishing time. The polishing rate can be calculated by dividing the difference between the initial film thickness and the final film thickness by the polishing time required to reach the final film thickness. As described above, the reference spectrum is acquired periodically each time the polishing table 3 rotates, so the polishing time at which each reference spectrum is acquired can be calculated from the rotation speed of the polishing table 3. In this way, the operation control unit 9 determines the film thickness corresponding to each reference spectrum (see step S106).

[0062] Each reference spectrum can be associated with (linked to) a corresponding film thickness. Therefore, the operation control unit 9 can determine the current film thickness of wafer W from the film thickness associated with the reference spectrum by determining the reference spectrum that most closely matches the shape of the measured spectrum during the polishing of wafer W.

[0063] Figure 5 shows an example of the process for polishing a wafer to be polished. In order to improve the uniformity of the film thickness of the wafer W to be polished, it is necessary to determine a specific location, which is a part of the circumference of the wafer W. Therefore, as shown in step S201 of Figure 5, the wafer W is transported to a film thickness measuring instrument 170, and the initial film thickness of the wafer W is measured by the film thickness measuring instrument 170.

[0064] Subsequently, similar to step S102 in Figure 4, the operation control unit 9 determines a specific position on the wafer W based on the film thickness of the wafer W measured by the film thickness measuring instrument 170 (see step S202).

[0065] The method for determining the specific position is the same as the method for determining the reference position. Based on the film thickness of the wafer W measured before polishing, the operation control unit 9 determines the maximum film thickness position where the maximum film thickness value was obtained (i.e., the location where the wafer W is thickest) and the minimum film thickness position where the minimum film thickness value was obtained (i.e., the location where the wafer W is thinnest), and determines at least one of the maximum film thickness position and the minimum film thickness position as the specific position.

[0066] In one embodiment, the operation control unit 9 may determine the maximum film thickness value and the minimum film thickness value based on the measured film thickness of the wafer W measured before polishing, calculate the difference between the overall average film thickness value of the wafer W and the maximum film thickness value, and the difference between the overall average film thickness value of the wafer W and the minimum film thickness value, and determine the position on the wafer W where the film thickness value with the largest difference is obtained as a specific position.

[0067] The operation control unit 9 acquires the film thickness distribution information of the wafer W measured by the film thickness measuring instrument 170 and determines a specific position on the wafer W. In one embodiment, if the film thickness measuring instrument 170 is located outside the polishing apparatus, the operation control unit 9 may acquire only the position information of the specific position determined from the film thickness distribution of the wafer W.

[0068] After determining a specific position on the wafer W, the motion control unit 9 starts polishing the wafer W (see step S203). During this polishing, light is shone onto the surface of the wafer W, and the motion control unit 9 acquires the spectrum of the reflected light from the wafer W (i.e., the measurement spectrum). The motion control unit 9 determines the reference spectrum that is closest in shape to the acquired measurement spectrum and acquires the film thickness associated with the determined reference spectrum (see step S204).

[0069] The motion control unit 9 adjusts the pressing force on the polishing surface 2a of the wafer W based on the film thickness of the wafer W by controlling the pressure regulators R1, R2, R3, and R4. In this embodiment, the motion control unit 9 divides a region on the wafer W into multiple pressing regions A1, A2, A3, and A4 corresponding to multiple pressure chambers 70, 71, 72, and 73 (see Figure 6).

[0070] Figure 6 shows a wafer divided into multiple pressing regions. In Figure 6, the region on the wafer W is divided into pressing region A1 corresponding to pressure chamber 70, pressing region A2 corresponding to pressure chamber 71, pressing region A3 corresponding to pressure chamber 72, and pressing region A4 corresponding to pressure chamber 73. Pressing region A1 has a circular shape, and each of pressing regions A2 to A4 has an annular shape. These pressing regions A1 to A4 are arranged concentrically with the center CPW of the wafer W. The operation control unit 9 is configured to independently adjust the pressing force on the wafer W for each of the multiple pressing regions.

[0071] As shown in Figure 6, a specific position IP exists in the pressing region A4 of the wafer W. In the embodiment shown in Figure 6, the specific position IP is a single point on the wafer W, but the specific position IP may be multiple points located in a narrow area on the wafer W, or multiple points located in a wide area on the wafer W. Therefore, the operation control unit 9 determines the control target region CA that includes the specific position IP. Furthermore, by setting a control target region of a certain size that includes the specific position IP, the adjustment of the uniformity of the film thickness, as described below, can be performed stably. In this embodiment, the control target region CA is determined within a range in the circumferential direction (i.e., a range belonging to any of regions A1 to A4). In one embodiment, if the specific position IP is a single point on the wafer W, the control target region CA may also be a single point on the wafer W.

[0072] The operation control unit 9 determines the target film thickness value in the control area CA and calculates the overall average film thickness value of the wafer W based on the film thickness of the wafer W measured by the film thickness sensor 40. The target film thickness value may correspond to the maximum or minimum film thickness value determined based on the film thickness of the wafer W measured by the film thickness sensor 40, or it may be both the maximum and minimum film thickness values. In one embodiment, the target film thickness value may be the average value of multiple film thickness values ​​in the control area CA.

[0073] The motion control unit 9 controls at least one of the rotation speeds of the polishing head 1 and the polishing table 3 so that the film thickness sensor 40 crosses the controlled area CA on the wafer W. For this control, the motion control unit 9 needs to determine the position of the controlled area CA while polishing the wafer W.

[0074] As an example of a method for determining the position of the controlled region CA, the motion control unit 9 identifies a reference position (for example, the notch position Nt in Figure 6) of the circumferential angle of the wafer W (i.e., the wafer angle) during the polishing of the wafer W, and determines the position of the controlled region CA as the wafer angle.

[0075] Assuming that the wafer W does not shift circumferentially relative to the polishing head 1, the operation control unit 9 can determine the notch position Nt and the position of the controlled area CA by keeping the mounting angle of the wafer W relative to the polishing head 1 constant at the start of polishing and by knowing the rotation angle of the polishing head 1 using the rotary encoder 152 (see Figure 7). Even without determining the position of the notch position Nt, the positional relationship between the notch position Nt and the controlled area CA is predetermined, so it is possible to determine the position of the controlled area CA from the rotation angle of the polishing head 1.

[0076] On the other hand, the wafer W may shift circumferentially relative to the polishing head 1 due to the frictional force acting between the wafer W and the polishing pad 1. In this case, the relative angle between the notch position Nt and the polishing head 1 also shifts. Therefore, the motion control unit 9 identifies the notch position Nt of the wafer W in real time while polishing the wafer W and determines the position of the controlled area CA based on the notch position Nt.

[0077] Figure 7 shows a notch detection device. As shown in Figure 7, the polishing apparatus may include a notch detection device 151 that detects the notch position Nt of the wafer W. The notch detection device 151 may consist of sensors such as an eddy current sensor, an optical sensor, or an image sensor. In the embodiment shown in Figure 7, the notch detection device 151 is located to the side of the polishing table 3. The polishing head 1 moves to a position where the peripheral edge of the wafer W held by the polishing head 1 (more specifically, the notch position Nt) extends beyond the polishing pad 2, and rotates the wafer W.

[0078] The notch detection device 151 detects the notch position Nt of the wafer W as it rotates with the wafer extending beyond the polishing pad 2, and outputs a detection signal to the operation control unit 9. The rotary encoder 152 detects a signal corresponding to the rotation angle of the polishing head 1, and outputs a detection signal to the operation control unit 9. In this way, the operation control unit 9 can obtain the relationship between the notch position Nt and the rotation angle of the polishing head 1, and determine the relative angle between the notch position Nt and the polishing head 1 in real time. In one embodiment, the operation control unit 9 may determine the notch position Nt based on a signal output from the film thickness sensor 40. In this case, the film thickness sensor 40 corresponds to the notch detection device.

[0079] Figures 8(a) and 8(b) show the movement path of the film thickness sensor across the surface of the wafer. In Figures 8(a) and 8(b), the movement path of the film thickness sensor 40 is shown by five dotted lines. In the embodiments shown in Figures 8(a) and 8(b), the film thickness sensor 40 crosses a specific position IP during the first rotation of the polishing table 3.

[0080] As shown in Figures 8(a) and 8(b), the motion control unit 9 can control the movement path of the film thickness sensor 40 by controlling at least one of the rotational speeds of the polishing head 1 and the polishing table 3. Therefore, the motion control unit 9 controls at least one of the rotational speeds of the polishing head 1 and the polishing table 3 based on a determined relative angle so that the film thickness sensor 40 crosses a specific position IP on the surface of the wafer W.

[0081] For example, the motion control unit 9 can determine the movement path of the film thickness sensor 40 by determining the rotation speed ratio between the rotation speed of the polishing head 1 and the rotation speed of the polishing table 3. The rotation speed ratio in the embodiment shown in Figure 8(a) and the rotation speed ratio in the embodiment shown in Figure 8(b) are different from each other. Therefore, when the relative angle between the notch position Nt and the polishing head 1 is changed, the motion control unit 9 determines the rotation speed ratio between the rotation speed of the polishing head 1 and the rotation speed of the polishing table 3 so that the film thickness sensor 40 traverses a specific position IP on the surface of the wafer W.

[0082] In this way, the operation control unit 9 measures the film thickness of the control target region CA, including a specific position IP during polishing, based on the signal output from the film thickness sensor 40, and controls the pressure in the pressure chambers 70 to 73 of the polishing head 1 corresponding to the control target region CA by controlling the pressure regulators R1 to R4 based on the measured film thickness.

[0083] More specifically, as shown in step S205 of Figure 5, the operation control unit 9 controls the pressure in the pressure chambers 70-73 of the polishing head 1 corresponding to a specific position IP (or controlled region CA) so that the difference between the controlled film thickness value and the overall average film thickness value of the wafer W is reduced. In the embodiment shown in Figure 6, the controlled region CA is located on the wafer W at a position corresponding to the pressing region A4, and region A4 corresponds to the pressure chamber 73. Therefore, the operation control unit 9 controls the pressure regulator R4 to control the pressure in the pressure chamber 73.

[0084] The operation control unit 9 divides the multiple pressing regions A1 to A4 on the wafer W, which are divided according to the multiple pressure chambers 70 to 73, into a specific pressing region including a specific position IP and other pressing regions excluding the specific pressing region. In this embodiment, the specific pressing region corresponds to pressing region A4, and the other pressing regions correspond to pressing regions A1 to A3.

[0085] The motion control unit 9 calculates the average film thickness value in each of the other pressing regions A1 to A3 based on the film thickness of the wafer W measured by the film thickness sensor 40. Subsequently, the motion control unit 9 controls the pressure in the pressure chambers 70 to 72 corresponding to the other pressing regions A1 to A3 by controlling each of the pressure regulators R1 to R3 so as to reduce the difference between the average film thickness values ​​of each of the other pressing regions A1 to A3 and the overall average film thickness value of the wafer W.

[0086] Figures 9(a) and 9(b) are diagrams illustrating the effects of the polishing process according to this embodiment. Figure 9(a) shows the average film thickness profile of wafer W before and after polishing using a comparative example polishing process, and Figure 9(b) shows the average film thickness profile of wafer W before and after polishing using the polishing process according to this embodiment. In both Figures 9(a) and 9(b), the horizontal axis represents the distance from the center CPW of wafer W, and the vertical axis represents the film thickness of wafer W. In Figures 9(a) and 9(b), the film thickness of wafer W is represented as a box plot as the film thickness at each measurement point within the pressing region A1 to A4.

[0087] As shown in Figure 9(a), the minimum film thickness value in pressing region A3 of the wafer W before polishing is particularly small (or thin) compared to the film thicknesses in the other pressing regions A1, A2, and A4. Also, the maximum film thickness value in pressing region A4 is particularly large (or thick) compared to the film thicknesses in the other pressing regions A1, A2, and A3. In the polishing process as a comparative example, the motion control unit 9 calculates the average film thickness value in each of the pressing regions A1 to A4 and the overall average film thickness value of the wafer W based on the signal detected by the film thickness sensor 40. Therefore, since the motion control unit 9 calculates the average film thickness values ​​for pressing regions A3 and A4, the difference between the average film thickness values ​​for pressing regions A1 and A2 and the average film thickness values ​​for pressing regions A3 and A4 may be small.

[0088] Even in such cases, the operation control unit 9 polishes the wafer W by controlling the pressure in each of the pressure chambers 70 to 73 so that the difference between the average film thickness of each of the pressing regions A1 to A4 and the overall average film thickness of the wafer W is reduced. Therefore, after polishing, the overall film thickness of the wafer W may not fall within a predetermined (desired) allowable range.

[0089] According to this embodiment, the operation control unit 9 individually controls the pressure of specific pressing regions with a different pressure than that of other pressing regions. More specifically, the operation control unit 9 controls the pressure in pressure chambers 72 and 73 so as to reduce the difference between the controlled film thickness value in each of the specific pressing regions A3 and A4 and the overall average film thickness value of the wafer W, and controls the pressure in pressure chambers 70 and 71 so as to reduce the difference between the average film thickness values ​​in each of the other pressing regions A1 and A2 and the overall average film thickness value of the wafer W. As shown in Figure 9(b), the operation control unit 9 may determine a plurality of specific pressing regions and individually control the pressure in the determined plurality of specific pressing regions.

[0090] In the embodiment shown in Figure 9(b), since the controlled film thickness value in pressing region A3 is smaller than the average film thickness value, the pressure in the pressure chamber 72 is reduced compared to the pressure in the comparative example. As a result, the amount of polishing in pressing region A3 is generally smaller compared to the amount of polishing in the comparative example. Since the controlled film thickness value in pressing region A4 is larger than the average film thickness value, the pressure in the pressure chamber 73 is increased compared to the pressure in the comparative example. As a result, the amount of polishing in pressing region A4 is generally larger compared to the amount of polishing in the comparative example. With this configuration, the polishing head 1 can bring the film thickness of the thickest and thinnest parts of the wafer W within a desired tolerance range (see Figure 9(b)). As a result, the overall uniformity of the film thickness of the wafer W can be improved.

[0091] In the embodiments described above, the polishing head has a plurality of pressure chambers (airbags), but the technical concept of the present invention is applicable to any polishing head having concentrically arranged pressing elements. The pressing force applied by the concentrically arranged pressing elements to the substrate is controlled based on the target film thickness value in a control target region including a specific position. Examples of pressing elements include piezoelectric elements.

[0092] In the embodiments described above, the film thickness is estimated by determining a reference spectrum whose shape is closest to the measured spectrum, but other algorithms may also be used to estimate the film thickness.

[0093] In the embodiment described above, the operation control unit 9 is configured to determine a specific position on the wafer W based on the film thickness of the wafer W measured by the film thickness measuring instrument 170, and to control the pressure in the pressure chamber of the polishing head 1 corresponding to the specific position. In one embodiment, the operation control unit 9 may be configured to control the pressure in the pressure chamber of the polishing head 1 without measuring the film thickness of the wafer W in advance. The configuration of such an operation control unit 9 will be described below with reference to the drawings.

[0094] Figure 10 shows the pressure control flow in the pressure chamber by the motion control unit. As shown in step S301 of Figure 10, the motion control unit 9 uses the film thickness sensor 40 to identify the maximum and minimum film thickness values ​​from the total film thickness of the wafer W obtained during the polishing of the wafer W. More specifically, the motion control unit 9 identifies the maximum and minimum film thickness values ​​for the entire wafer W from the signal output from the film thickness sensor 40.

[0095] The motion control unit 9 divides the area on the wafer W into multiple pressing regions A1, A2, A3, and A4 corresponding to the multiple pressure chambers 70, 71, 72, and 73. In other words, the motion control unit 9 divides each measurement data acquired by the film thickness sensor 40 for each pressing region A1, A2, A3, and A4 based on the trajectory of the film thickness sensor 40 as it crosses the surface of the wafer W. The motion control unit 9 identifies the maximum and minimum film thickness values, as well as the average film thickness value for each of the multiple pressing regions A1, A2, A3, and A4. Furthermore, the motion control unit 9 also identifies the average film thickness value for the entire wafer W.

[0096] As shown in step S302 of Figure 10, the operation control unit 9 determines whether the difference between the maximum and minimum film thickness values ​​over the entire wafer W (i.e., the film thickness range) is within a desired (predetermined) acceptable range. If the film thickness range is within the acceptable range (see "YES" in step S302), the operation control unit 9 controls the pressure in each pressure chamber by controlling each of the pressure regulators so that the difference between the average film thickness value of each pressing region and the average film thickness value of the entire wafer W is reduced (see step S303).

[0097] If the film thickness range is outside the acceptable range (see "NO" in step S302), the operation control unit 9 identifies at least one of the pressure chambers corresponding to the position of the wafer W where the maximum film thickness value was detected and the pressure chamber corresponding to the position of the wafer W where the minimum film thickness value was detected (see step S304).

[0098] When controlling the pressure in a pressure chamber related to the maximum film thickness, the operation control unit 9 controls the pressure in the pressure chamber so that the average film thickness of the wafer W corresponding to the target pressure chamber is lower than the overall average film thickness of the wafer W (see step S305A). When controlling the pressure in a pressure chamber related to the minimum film thickness, the operation control unit 9 controls the pressure in the pressure chamber so that the average film thickness of the wafer W corresponding to the target pressure chamber is higher than the overall average film thickness of the wafer W (see step S305B).

[0099] Specifically, when controlling the pressure in a pressure chamber related to the maximum film thickness value, the operation control unit 9 calculates a target film thickness value that is reduced by a predetermined amount or a predetermined percentage from the overall average film thickness value of the wafer W, and adjusts the pressure in the target pressure chamber so that the average film thickness value of the pressing region to which the maximum film thickness measurement point belongs approaches the target film thickness value. More specifically, if the average film thickness value of the pressing region to which the maximum film thickness measurement point belongs exceeds the target film thickness value, the operation control unit 9 increases the pressure in the pressure chamber related to the pressing region to which the maximum film thickness measurement point belongs.

[0100] To reduce the film thickness range, the operation control unit 9 may control only the pressure in the pressure chamber related to the maximum film thickness as described above, or only the pressure in the pressure chamber related to the minimum film thickness as described above, or it may control both the pressure in the pressure chamber related to the maximum film thickness and the pressure in the pressure chamber related to the minimum film thickness as described above. For the other pressure chambers, the operation control unit 9 controls them so that the difference between the average film thickness of the corresponding pressing region and the overall average film thickness of the wafer W is reduced.

[0101] With this configuration, when the film thickness range is outside the acceptable range, the amount of polishing in the pressing area corresponding to the maximum film thickness or the polishing speed within a certain period will be larger than when the present invention is not applied, and the amount of polishing in the pressing area corresponding to the minimum film thickness or the polishing speed within a certain period will be smaller than when the present invention is not applied. As a result, the polishing head 1 can keep the difference between the film thickness of the thickest part of the wafer W and the film thickness of the thinnest part of the wafer W within the desired acceptable range.

[0102] Figure 11 is a diagram illustrating the effects of the polishing process according to another embodiment. In the embodiment shown in Figure 11, during the polishing of the wafer W, the maximum and minimum film thickness values ​​in the pressing regions A1 and A2 are within the acceptable range. Therefore, the operation control unit 9 controls the pressure in the pressure chambers 70 and 71 corresponding to the pressing regions A1 and A2, respectively, so that the difference between the average film thickness values ​​of the pressing regions A1 and A2 and the overall average film thickness value of the wafer W is reduced.

[0103] Since the minimum film thickness in the pressing region A3 is outside the acceptable range, the operation control unit 9 controls the pressure in the pressure chamber 72 so that the average film thickness in the pressing region A3 exceeds the overall average film thickness of the wafer W. As a result, the amount of polishing in the pressing region A3 is reduced, and the polishing head 1 can keep the film thickness in the pressing region A3 within the acceptable range.

[0104] Since the maximum film thickness in the pressing region A4 is outside the acceptable range, the operation control unit 9 controls the pressure in the pressure chamber 73 so that the average film thickness in the pressing region A4 is lower than the overall average film thickness of the wafer W. As a result, the amount of polishing in the pressing region A4 increases, and the polishing head 1 can keep the film thickness in the pressing region A4 within the acceptable range.

[0105] According to this embodiment, the operation control unit 9 can keep the difference in film thickness within the wafer W surface within an acceptable range based on the film thickness of the wafer W measured by the film thickness sensor 40 during the polishing of the wafer W, without having to measure the film thickness of the wafer W in advance.

[0106] Furthermore, if the film thickness range is still outside the acceptable range in the pressing regions on the wafer W, excluding the pressing region on the wafer W corresponding to the maximum film thickness value and the pressing region on the wafer W corresponding to the minimum film thickness value, the operation control unit 9 may perform pressure control of the pressing region in the same manner as described above.

[0107] In one embodiment, the operation control unit 9 may determine the maximum and minimum film thickness values ​​on the wafer W based on the film thickness of the wafer W obtained at regular time intervals during the polishing of the wafer W. For example, the rotational speed ratio between the polishing table 3 and the polishing head 1 (rotational speed of the polishing table 3 / rotational speed of the polishing head 1) is 100 / 90 min -1 In this case, the polishing table 3 rotates 10 more times relative to the polishing head 1 in 60 seconds.

[0108] With the above rotation speed ratio, the polishing table 3 rotates 10 times in 6 seconds and the polishing head 1 rotates 9 times in 6 seconds, so the relative positions of the polishing table 3 and the polishing head 1 return to their original positions once every 6 seconds. Since the film thickness sensor 40 is embedded in the polishing table 3, the number of times the film thickness sensor 40 crosses the surface of the wafer W depends on the rotation of the polishing table 3. Therefore, the movement path of the film thickness sensor 40 returns to its original position once every 6 seconds. Thus, the operation control unit 9 may determine the maximum and minimum film thickness values ​​based on the film thickness of the wafer W obtained during the time interval until the movement path of the film thickness sensor 40 returns to its original position.

[0109] In one embodiment, the operation control unit 9 may determine the maximum and minimum film thickness values ​​in each of the multiple pressing regions A1, A2, A3, and A4 each time the polishing table 3 rotates once (i.e., each time the film thickness sensor 40 passes through one movement path), and control the pressure in each of the pressure chambers 70, 71, 72, and 73.

[0110] If the pressure in each of the pressure chambers 70, 71, 72, and 73 is controlled each time the film thickness sensor 40 passes through one movement path, the operation control unit 9 may start the next pressure adjustment before the polishing due to the controlled (adjusted) pressure has progressed and been reflected in the change in the film thickness of the wafer W.

[0111] Furthermore, if the difference between the maximum and minimum film thickness values ​​is calculated based on the film thickness measurement results performed within a certain period, and the pressure in the relevant pressure chamber is adjusted too frequently, the pressure responsiveness of the elastic membrane may not be controlled properly. Therefore, it is desirable for the operation control unit 9 to check the next film thickness range at a certain interval, allowing a period of time for the pressure adjustment in the pressure chamber to take effect. Alternatively, the operation control unit 9 may perform another film thickness measurement at the same measurement point after the pressure adjustment to confirm the results of the pressure adjustment.

[0112] When the motion control unit 9 determines the maximum and minimum film thickness values, the polishing table 3 and polishing head 1 are always rotating, and the polishing of the wafer W is always progressing. Therefore, for example, if the time interval is set to 6 seconds, in the relationship between the film thickness of wafer W acquired at 1 second and the film thickness of wafer W acquired at 5 seconds, the motion control unit 9 will find the film thickness acquired at 5 seconds to be thinner than the film thickness acquired at 1 second, and will not be able to accurately evaluate the actual uniformity of the film thickness. Therefore, the motion control unit 9 is configured to correct the film thickness value of wafer W at each acquisition timing based on the polishing speed of wafer W.

[0113] Figure 12 is a diagram showing the flow of correction of the film thickness value by the motion control unit. As shown in step S401 of Figure 12, the motion control unit 9 calculates the polishing speed of the wafer W during polishing from the film thickness of the wafer W acquired by the film thickness sensor 40. Then, based on the polishing speed of the wafer W, the motion control unit 9 calculates the amount of change in the film thickness of the wafer W between the acquisition time when the film thickness of the wafer W was acquired by the film thickness sensor 40 at each measurement point of the wafer W and a predetermined reference time (see step S402).

[0114] The operation control unit 9 corrects the film thickness of the wafer W obtained during polishing of the wafer W at regular time intervals, using the change in film thickness as a correction value (see step S403). For example, if a predetermined reference time is set to the start time of the above time interval, i.e., 0 seconds, the film thickness of the wafer W gradually decreases from the reference time, so the operation control unit 9 corrects the film thickness of the wafer W by adding the decrease in film thickness as a correction value to the film thickness of the wafer W obtained during polishing.

[0115] Conversely, if the predetermined reference time is set to the end time of the above time interval (6 seconds in the embodiment described above), the film thickness of the wafer W will be measured to be thicker than the film thickness at the reference time. Therefore, the operation control unit 9 corrects the film thickness of the wafer W by subtracting the change in film thickness as a correction value from the film thickness of the wafer W obtained during polishing. Whether the reference time is set to the start time of the above time interval or to an intermediate time can be arbitrarily determined.

[0116] After step S403, the operation control unit 9 determines the maximum and minimum film thickness values ​​based on the corrected wafer W film thickness (see step S404). After step S404, the operation control unit 9 controls the pressures in pressure chambers 70, 71, 72, and 73 in the same manner as the pressure control flow shown in Figure 10.

[0117] In the embodiments described above, the case where the pressure chamber associated with the maximum film thickness and the pressure chamber associated with the minimum film thickness are separate (or different) pressure chambers was explained. However, there are also cases where the pressure chamber associated with the maximum film thickness and the pressure chamber associated with the minimum film thickness are the same pressure chamber. In this case, the operation control unit 9 may pre-determine, by setting a polishing recipe, whether to control the pressure of the target pressure chamber so that the average film thickness of the wafer W corresponding to that pressure chamber is lower than the overall average film thickness of the wafer W, or to control the pressure of the target pressure chamber so that the average film thickness of the wafer W corresponding to that pressure chamber is higher than the overall average film thickness of the wafer W.

[0118] In one embodiment, if the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, the operation control unit 9 may calculate a first difference between the maximum film thickness value and the overall average film thickness value of the wafer W, and a second difference between the minimum film thickness value and the overall average film thickness value of the wafer W.

[0119] The operation control unit 9 compares the first difference and the second difference. If the first difference is greater than the second difference, it may control the pressure in the target pressure chamber so that the average film thickness value of the wafer W corresponding to the pressure chamber associated with the maximum film thickness value is lower than the overall average film thickness value of the wafer W. If the second difference is greater than the first difference, the operation control unit 9 may control the pressure in the target pressure chamber so that the average film thickness value of the wafer W corresponding to the pressure chamber associated with the minimum film thickness value is higher than the overall average film thickness value of the wafer W.

[0120] In the embodiment described above, the difference between the maximum film thickness and the overall average film thickness of the wafer W was defined as the first difference, and the difference between the minimum film thickness and the overall average film thickness of the wafer W was defined as the second difference. However, the difference between the maximum film thickness and the average film thickness in the pressing region corresponding to the maximum film thickness may be defined as the first difference, and the difference between the minimum film thickness and the average film thickness in the pressing region corresponding to the minimum film thickness may be defined as the second difference.

[0121] In the embodiments described above, the operation control unit 9 determines whether the difference between the maximum film thickness value and the minimum film thickness value (film thickness range) is within a desired (predetermined) allowable range, and adjusts the pressure in the pressure chamber related to the maximum film thickness value and / or the pressure chamber related to the minimum film thickness value if it is outside the allowable range. In one embodiment, the operation control unit 9 may adjust the pressure in the pressure chamber related to the maximum film thickness value and / or the pressure chamber related to the minimum film thickness value without comparing the difference between the maximum film thickness value and the minimum film thickness value with the allowable range. In this case as well, the pressure in the pressure chamber is controlled so that the average film thickness value of the pressing area related to the maximum film thickness value is lower than the overall average film thickness value of the wafer W, and the pressure in the pressure chamber is controlled so that the average film thickness value of the pressing area related to the minimum film thickness value is higher than the overall average film thickness value of the wafer W. As a result, the difference between the maximum film thickness value and the minimum film thickness value is reduced, and the uniformity of the film thickness of the wafer W can be improved.

[0122] The embodiments described above are intended to enable persons with ordinary skill in the art to implement the present invention. Various modifications of the above embodiments can be made naturally by those skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments as well. Therefore, the present invention is not limited to the embodiments described, but is to be interpreted in the broadest sense according to the technical idea defined by the claims. [Explanation of Symbols]

[0123] 1 Polishing head 2 polishing pads 2a Polished surface 3 Polishing Table 5. Polishing fluid supply nozzle 6 Table motors 7 Optical sensor head 9. Operation Control Unit 9a Storage device 9b Arithmetic unit 10 Head Shaft 21 Head body 40 Film Thickness Sensor 44 Light source 47 Spectrometer 60 Retainer Rings 60a Bottom 60b top surface 62 drive rings 65 Elastic membrane 65a Substrate pressing surface 70 Central pressure chamber 71 Intermediate pressure chamber 72 Intermediate pressure chamber 73 Edge pressure chamber 80 Retainer ring pressing device 81 Piston 82 Rolling Diaphragm 83 Retainer Ring Pressure Chamber 151 Notch detection device 152 Rotary Encoder 170 Film Thickness Gauge

Claims

1. a polishing table supporting a polishing pad; a polishing head having a plurality of concentrically divided pressure chambers for pressing the substrate against the polishing surface of the polishing pad; a plurality of pressure regulators coupled to the plurality of pressure chambers; a film thickness sensor embedded in the polishing table for outputting a signal corresponding to a film thickness of the substrate; an operation control unit that controls the pressure of each of the plurality of pressure chambers individually through the plurality of pressure regulators; The operation control unit is acquiring information about a specific position that is a portion on a circumference of the substrate, and calculating a control target film thickness value in a control target region that includes the specific position and an average film thickness value of the entire substrate; a polishing apparatus that controls a pressure in a pressure chamber of the polishing head corresponding to the specific position so as to reduce a difference between the control target film thickness value and an average film thickness value of the entire substrate.

2. 2. The polishing apparatus according to claim 1, wherein the operation control section identifies the specific position based on a film thickness of the substrate measured before polishing.

3. The operation control unit is determining a maximum film thickness position at which a maximum film thickness value is obtained and a minimum film thickness position at which a minimum film thickness value is obtained based on the film thickness of the substrate measured before polishing; 3. The polishing apparatus according to claim 1, wherein at least one of the maximum film thickness position and the minimum film thickness position is determined as the specific position.

4. The operation control unit is determining a maximum film thickness value and a minimum film thickness value based on a film thickness measured on the substrate before polishing; calculating a difference between an average film thickness value over the entire substrate and the maximum film thickness value, and a difference between an average film thickness value over the entire substrate and the minimum film thickness value; 3. The polishing apparatus according to claim 1, wherein the position on the substrate where the film thickness value having the largest difference is obtained is determined as the specific position.

5. The polishing apparatus according to any one of claims 1 to 4, wherein the control target film thickness value corresponds to at least one of a maximum film thickness value and a minimum film thickness value determined based on a film thickness of the substrate measured before polishing.

6. 5. The polishing apparatus according to claim 1, wherein the control target film thickness value is an average value of a plurality of film thickness values ​​within the control target region.

7. The operation control unit is measuring a film thickness in the control target region including the specific position during polishing based on a signal output from the film thickness sensor; 7. The polishing apparatus according to claim 1, further comprising: a pressure control unit that controls a pressure in a pressure chamber of the polishing head that corresponds to the specific position based on the measured film thickness.

8. The operation control unit is Dividing the plurality of pressure regions on the substrate, which are divided according to the plurality of pressure chambers, into a specific pressure region including the control target region and other pressure regions excluding the specific pressure region; Calculating an average film thickness value in the other pressing region based on the film thickness of the substrate; The polishing apparatus according to any one of claims 1 to 7, further comprising: a pressure control section for controlling a pressure chamber corresponding to the other pressing region so as to reduce a difference between an average film thickness value of the other pressing region and an average film thickness value of the entire substrate.

9. The operation control unit is obtaining information about a reference location that is a portion of a circumference of a reference substrate different from the substrate; detecting a physical quantity corresponding to a film thickness in a region on the substrate including the reference position by the film thickness sensor during polishing of the reference substrate; acquiring a plurality of data corresponding to the film thickness of the reference substrate based on a plurality of signals sent from the film thickness sensor; 9. The polishing apparatus according to claim 1, wherein each of the plurality of data is associated with a film thickness of the reference substrate at the time when each of the plurality of data was acquired.

10. 10. The polishing apparatus according to claim 9, wherein the operation control section determines the reference position based on a film thickness of the reference substrate measured before polishing.

11. The polishing apparatus according to any one of claims 1 to 10, wherein the operation control unit controls at least one of the rotation speed of the polishing head and the rotation speed of the polishing table so that the film thickness sensor crosses the control target area.

12. The operation control unit is determining a relative angle between the reference position of the circumferential angle of the substrate and the rotation angle of the polishing head based on a relationship between the reference position and the rotation angle of the polishing head; 12. The polishing apparatus according to claim 11, further comprising: a rotation speed of the polishing head and / or a rotation speed of the polishing table, the rotation speed being controlled based on the determined relative angle.

13. A polishing method in which a substrate is pressed against a polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers divided concentrically, comprising the steps of: acquiring information about a specific position that is a portion on a circumference of the substrate, and calculating a control target film thickness value in a control target region that includes the specific position and an average film thickness value of the entire substrate; a pressure in a pressure chamber of the polishing head corresponding to the specific position is controlled so that a difference between the control target film thickness value and an average film thickness value of the entire substrate is reduced.

14. The polishing method according to claim 13, wherein the specific position is identified based on a film thickness of the substrate measured before polishing.

15. determining a maximum film thickness position at which a maximum film thickness value is obtained and a minimum film thickness position at which a minimum film thickness value is obtained based on the film thickness of the substrate measured before polishing; 15. The polishing method according to claim 13, wherein at least one of the maximum film thickness position and the minimum film thickness position is determined as the specific position.

16. determining a maximum film thickness value and a minimum film thickness value based on a film thickness measured on the substrate before polishing; calculating a difference between an average film thickness value over the entire substrate and the maximum film thickness value, and a difference between an average film thickness value over the entire substrate and the minimum film thickness value; 15. The polishing method according to claim 13, wherein a position on the substrate where the film thickness value having the largest difference is obtained is determined as the specific position.

17. The polishing method according to any one of claims 13 to 16, wherein the control target film thickness value corresponds to at least one of a maximum film thickness value and a minimum film thickness value determined based on a film thickness of the substrate measured before polishing.

18. 17. The polishing method according to claim 13, wherein the control target film thickness value is an average value of a plurality of film thickness values ​​within the control target region.

19. measuring a film thickness in the control target area including the specific position during polishing based on an output signal from the film thickness sensor; 19. The polishing method according to claim 13, further comprising controlling a pressure in a pressure chamber of the polishing head corresponding to the specific position based on the measured film thickness.

20. Dividing the plurality of pressure regions on the substrate, which are divided according to the plurality of pressure chambers, into a specific pressure region including the control target region and other pressure regions excluding the specific pressure region; Calculating an average film thickness value in the other pressing region based on the film thickness of the substrate; The polishing method according to any one of claims 13 to 19, further comprising controlling a pressure in a pressure chamber corresponding to the other pressing region so as to reduce a difference between an average film thickness value of the other pressing region and an average film thickness value of the entire substrate.

21. obtaining information about a reference location that is a portion of a circumference of a reference substrate different from the substrate; detecting a physical quantity corresponding to a film thickness in a region on the substrate including the reference position by the film thickness sensor during polishing of the reference substrate; acquiring a plurality of data corresponding to the film thickness of the reference substrate based on a plurality of signals sent from the film thickness sensor; 21. The polishing method according to claim 13, further comprising: associating each of the plurality of data with the film thickness of the reference substrate at the time when each of the plurality of data was acquired.

22. 22. The polishing method according to claim 21, wherein the reference position is determined based on a film thickness of the reference substrate measured before polishing.

23. The polishing method according to any one of claims 13 to 22, further comprising controlling at least one of a rotation speed of the polishing head and a rotation speed of the polishing table so that the film thickness sensor crosses the control target area by rotation of a polishing table supporting the polishing pad.

24. determining a relative angle between the reference position of the circumferential angle of the substrate and the rotation angle of the polishing head based on a relationship between the reference position and the rotation angle of the polishing head; 24. The polishing method according to claim 23, further comprising controlling at least one of a rotation speed of the polishing head and a rotation speed of the polishing table based on the determined relative angle.

25. a polishing table supporting a polishing pad; a polishing head having a plurality of concentrically divided pressure chambers for pressing the substrate against the polishing surface of the polishing pad; a plurality of pressure regulators coupled to the plurality of pressure chambers; a film thickness sensor embedded in the polishing table for outputting a signal corresponding to a film thickness of the substrate; an operation control unit that controls the pressure of each of the plurality of pressure chambers individually through the plurality of pressure regulators; The operation control unit is Identifying a maximum film thickness value and a minimum film thickness value from a film thickness of the substrate obtained during polishing of the substrate by the film thickness sensor; Identifying at least one of a pressure chamber corresponding to a position of the substrate where the maximum film thickness value is detected and a pressure chamber corresponding to a position of the substrate where the minimum film thickness value is detected; When controlling the pressure of the pressure chamber associated with the maximum film thickness value, the pressure of the pressure chamber associated with the maximum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate; A polishing apparatus, which controls the pressure of a pressure chamber associated with the minimum film thickness value so that, when controlling the pressure of the pressure chamber associated with the minimum film thickness value, the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value exceeds the overall average film thickness value of the substrate.

26. 26. The polishing apparatus according to claim 25, wherein the operation control section identifies the maximum film thickness value and the minimum film thickness value based on film thicknesses of the substrate obtained at regular time intervals while the substrate is being polished.

27. The operation control unit is calculating a polishing rate during polishing from the film thickness of the substrate obtained by the film thickness sensor; calculating an amount of change in a film thickness of the substrate between an acquisition time at which the film thickness of the substrate is acquired by the film thickness sensor at each measurement point on the substrate and a reference time based on the polishing rate; correcting a film thickness of the substrate obtained during polishing of the substrate during the time interval using the change amount as a correction value; 27. The polishing apparatus according to claim 26, wherein the maximum film thickness value and the minimum film thickness value are determined based on a corrected film thickness of the substrate.

28. The polishing apparatus of any one of claims 25 to 27, wherein, when a pressure chamber associated with the maximum film thickness value and a pressure chamber associated with the minimum film thickness value are the same pressure chamber, the operation control unit determines in advance by setting a recipe whether to control the pressure of the pressure chamber associated with the maximum film thickness value so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the overall average film thickness value of the substrate, or to control the pressure of the pressure chamber associated with the minimum film thickness value so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value is higher than the overall average film thickness value of the substrate.

29. The operation control unit is when the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, a first difference between the maximum film thickness value and an average film thickness value of the entire substrate is compared with a second difference between the minimum film thickness value and the average film thickness value of the entire substrate; When the first difference is greater than the second difference, the pressure of the pressure chamber associated with the maximum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate; A polishing apparatus according to any one of claims 25 to 27, wherein when the second difference is greater than the first difference, the pressure of the pressure chamber associated with the minimum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value exceeds the overall average film thickness value of the substrate.

30. The operation control unit is When the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, a first difference between the maximum film thickness value and an average film thickness value in a pressing region corresponding to the maximum film thickness value is compared with a second difference between the minimum film thickness value and the average film thickness value in a pressing region corresponding to the minimum film thickness value; When the first difference is greater than the second difference, the pressure of the pressure chamber associated with the maximum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate; A polishing apparatus according to any one of claims 25 to 27, wherein when the second difference is greater than the first difference, the pressure of the pressure chamber associated with the minimum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value exceeds the overall average film thickness value of the substrate.

31. A polishing method in which a substrate is pressed against a polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers divided concentrically, comprising the steps of: Identifying a maximum film thickness value and a minimum film thickness value from a film thickness of the substrate obtained during polishing of the substrate; Identifying at least one of a pressure chamber corresponding to a position of the substrate where the maximum film thickness value is detected and a pressure chamber corresponding to a position of the substrate where the minimum film thickness value is detected; When controlling the pressure of the pressure chamber associated with the maximum film thickness value, the pressure of the pressure chamber associated with the maximum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate; A polishing method, comprising: controlling the pressure of a pressure chamber associated with the minimum film thickness value such that an average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value exceeds an overall average film thickness value of the substrate.

32. 32. The polishing method according to claim 31, wherein the maximum film thickness value and the minimum film thickness value are identified based on film thicknesses of the substrate obtained at regular time intervals during polishing of the substrate.

33. Calculating a polishing rate during polishing from the film thickness of the substrate; calculating an amount of change in a film thickness of the substrate between an acquisition time at which the film thickness of the substrate is acquired at each measurement point on the substrate and a reference time based on the polishing rate; correcting a film thickness of the substrate obtained during polishing of the substrate during the time interval using the change amount as a correction value; 33. The polishing method according to claim 32, wherein the maximum film thickness value and the minimum film thickness value are identified based on the corrected film thickness of the substrate.

34. The polishing method according to any one of claims 31 to 33, wherein, when a pressure chamber associated with the maximum film thickness value and a pressure chamber associated with the minimum film thickness value are the same pressure chamber, it is determined in advance by setting a recipe whether to control the pressure of the pressure chamber associated with the maximum film thickness value so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the overall average film thickness value of the substrate, or to control the pressure of the pressure chamber associated with the minimum film thickness value so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value is higher than the overall average film thickness value of the substrate.

35. when the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, a first difference between the maximum film thickness value and an average film thickness value of the entire substrate is compared with a second difference between the minimum film thickness value and the average film thickness value of the entire substrate; When the first difference is greater than the second difference, the pressure of the pressure chamber associated with the maximum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate; A polishing method according to any one of claims 31 to 33, wherein when the second difference is greater than the first difference, the pressure of the pressure chamber associated with the minimum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value exceeds the overall average film thickness value of the substrate.

36. When the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, a first difference between the maximum film thickness value and an average film thickness value in a pressing region corresponding to the maximum film thickness value is compared with a second difference between the minimum film thickness value and the average film thickness value in a pressing region corresponding to the minimum film thickness value; When the first difference is greater than the second difference, the pressure of the pressure chamber associated with the maximum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate; A polishing method according to any one of claims 31 to 33, wherein when the second difference is greater than the first difference, the pressure of the pressure chamber associated with the minimum film thickness value is controlled so that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value exceeds the overall average film thickness value of the substrate.

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