Polishing apparatus 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 technology]

[0002] Chemical mechanical polishing (CMP) is a well-known technique used in the manufacturing process of semiconductor devices. A polishing apparatus for CMP includes a polishing table that supports a polishing pad and a polishing head that holds 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 polishing table and the polishing head are moved relative to each other, causing the wafer to slide against the polishing surface, thereby polishing the surface of the wafer.

[0004] Furthermore, a film thickness sensor detects signals corresponding to the wafer's film thickness and obtains the film thickness distribution on the wafer. The polishing endpoint is determined based on the film thickness distribution on the wafer, and the pressure of multiple airbags concentrically mounted on the polishing head is controlled. The film thickness sensor rotates with the polishing table, and the polishing head that holds the wafer also rotates. Therefore, the film thickness sensor's movement path across the wafer surface is different with each rotation of the polishing table. The film thickness distribution on the wafer is usually calculated as an average 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] International Publication No. 2015 / 163164 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, the required level of film thickness uniformity has increased. Therefore, it has become necessary to manage and control the polishing process with greater consideration given to variations in the initial film thickness of the wafer in the circumferential direction due to the characteristics of the film-forming equipment, and variations in the amount of polishing in the circumferential direction caused by polishing. (For example, it is effective to actively polish the areas of the wafer where the film is thick, or actively polish areas other than the areas where the film is thin, to improve the uniformity of the wafer film thickness.) Furthermore, with conventional methods, it can be difficult to keep the difference between the maximum and minimum film thicknesses within the wafer surface within an acceptable range.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a polishing apparatus and a polishing method that can improve the uniformity of the film thickness on a wafer. [Means for solving the problem]

[0008] In one aspect, a polishing apparatus is provided, comprising: a polishing table for supporting a polishing pad; a polishing head having a plurality of pressure chambers divided into concentric circles 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 for outputting a signal corresponding to the film thickness of the substrate; and an operation control unit for individually controlling the pressure of each of the plurality of pressure chambers via the plurality of pressure regulators. The operation control unit acquires information about a specific position on the circumference of the substrate, calculates a control target film thickness value in a control target region including the specific position and an average film thickness value for the entire 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 control target film thickness value and the average film thickness value for the entire substrate.

[0009] In one aspect, the operation control unit identifies the specific position based on a film thickness of the substrate measured before polishing. In one embodiment, the operation control unit determines a maximum film thickness position where the maximum film thickness value is obtained and a 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 aspect, 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 average film thickness value of the entire substrate and the maximum film thickness value, and the difference between the average film thickness value of the entire 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 a maximum film thickness value and a minimum film thickness value determined based on a film thickness of the substrate measured before polishing. In one aspect, the control target film thickness value is an average value of a plurality of film thickness values ​​within the control target region. In one aspect, the operation control unit measures the film thickness of the control target area including the specific position during polishing based on the 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 aspect, the operation control unit divides the multiple pressure areas on the substrate, which are divided according to the multiple pressure chambers, into a specific pressure area including the control target area and other pressure areas excluding the specific pressure area, calculates an average film thickness value in the other pressure areas based on the film thickness of the substrate, and controls the pressure in the pressure chambers corresponding to the other pressure areas so that the difference between the average film thickness value in the other pressure areas and the average film thickness value of the entire substrate is reduced. In one aspect, the operation control unit acquires information regarding a reference position, which is a portion on the circumference of a reference substrate different from the substrate, and during polishing of the reference substrate, detects a physical quantity corresponding to the film thickness of a region on the substrate including the reference position using the film thickness sensor, acquires multiple data corresponding to the film thickness of the reference substrate based on multiple signals sent from the film thickness sensor, and associates each of the multiple data with the film thickness of the reference substrate at the time each of the multiple data was acquired. In one aspect, the operation control unit determines the reference position based on a film thickness of the reference substrate measured before polishing.

[0012] In one embodiment, 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. In one aspect, the operation control unit determines the reference position and the relative angle of the polishing head based on the relationship between the reference position of the circumferential angle of the substrate and the rotational angle of the polishing head, and controls at least one of the rotational speed of the polishing head and the rotational speed of the polishing table based on the determined relative angle.

[0013] 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, the polishing method acquires information about a specific position on the circumference of the substrate, calculates a control target film thickness value in a control target region including the specific position and an average film thickness value for the entire 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 control target film thickness value and the average film thickness value for the entire substrate.

[0014] In one embodiment, the specific position is identified based on a film thickness of the substrate measured before polishing. In one embodiment, based on the film thickness of the substrate measured before polishing, a maximum film thickness position where the maximum film thickness value is obtained and a 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 as the specific position. In one embodiment, a maximum film thickness value and a minimum film thickness value are determined based on the film thickness of the substrate measured before polishing, and the difference between the average film thickness value of the entire substrate and the maximum film thickness value, and the difference between the average film thickness value of the entire 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 to be the specific position.

[0015] In one embodiment, the controlled 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. In one aspect, the control target film thickness value is an average value of a plurality of film thickness values ​​within the control target region. In one aspect, the film thickness of the control target area 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 aspect, the multiple pressure regions on the substrate divided according to the multiple pressure chambers are divided into a specific pressure region including the control target region and other pressure regions excluding the specific pressure region, and an average film thickness value in the other pressure regions is calculated based on the film thickness of the substrate, and the pressure in the pressure chamber corresponding to the other pressure region is controlled so that the difference between the average film thickness value in the other pressure region and the average film thickness value of the entire substrate is reduced. In one aspect, information regarding a reference position, which is a portion on the circumference of a reference substrate different from the substrate, is acquired, and during polishing of the reference substrate, the film thickness sensor detects a physical quantity corresponding to the film thickness of a region on the substrate including the reference position, and based on multiple signals sent from the film thickness sensor, multiple pieces of data corresponding to the film thickness of the reference substrate are acquired, and each of the multiple pieces of data is associated with the film thickness of the reference substrate at the time each of the multiple pieces of data was acquired. In one embodiment, the reference position is determined based on a film thickness of the reference substrate measured before polishing.

[0017] In one embodiment, at least one of the rotation speed of the polishing head and the rotation speed of the polishing table is controlled so that the film thickness sensor crosses the control target area by rotating a polishing table supporting the polishing pad. In one aspect, 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 rotational angle of the polishing head, and at least one of the rotational speed of the polishing head and the rotational speed of the polishing table is controlled based on the determined relative angle.

[0018] In one aspect, a polishing apparatus is provided that includes 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 in each of the plurality of pressure chambers via the plurality of pressure regulators. The operation control unit identifies a maximum film thickness value and a minimum film thickness value from the film thickness of the substrate obtained by the film thickness sensor during polishing of the substrate, identifies at least one of the pressure chamber corresponding to the position of the substrate where the maximum film thickness value was detected and the pressure chamber corresponding to the position of the substrate where the minimum film thickness value was detected, and when controlling the pressure of the pressure chamber associated with the maximum film thickness value, controls 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, and when controlling the pressure of the pressure chamber associated with the minimum film thickness value, controls 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.

[0019] In one aspect, the operation control unit 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. In one aspect, the operation control unit calculates a polishing rate during polishing from the film thickness of the substrate acquired by the film thickness sensor, calculates an amount of change in film thickness of the substrate between an acquisition time when 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, corrects the film thickness of the substrate acquired during polishing of the substrate at the time interval using the amount of change as a correction value, 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 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 determines in advance by recipe settings 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 average film thickness value of the entire 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 average film thickness value of the entire substrate. In one aspect, 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, the operation control unit compares a first difference between the maximum film thickness value and the overall average film thickness value of the substrate with a second difference between the minimum film thickness value and the overall average film thickness value of the substrate, and when the first difference is greater than the second difference, controls 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, and when the second difference is greater than the first difference, controls 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. In one aspect, 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, the operation control unit compares a first difference between the maximum film thickness value and the average film thickness value in the pressing area corresponding to the maximum film thickness value with a second difference between the minimum film thickness value and the average film thickness value in the pressing area corresponding to the minimum film thickness value, and when the first difference is greater than the second difference, controls 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 average film thickness value of the entire substrate, and when the second difference is greater than the first difference, controls 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 average film thickness value of the entire substrate.

[0021] In one aspect, a polishing method is provided in which a substrate is pressed against a polishing surface of a polishing pad using a polishing head having a plurality of concentrically divided pressure chambers, the method including: determining 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 on the substrate where the maximum film thickness value was detected and a pressure chamber corresponding to a position on the substrate where the minimum film thickness value was detected; and controlling the pressure of the pressure chamber corresponding to the maximum film thickness value so that the average film thickness of the substrate corresponding to the pressure chamber corresponding to the maximum film thickness value is less than the average film thickness of the entire substrate; and controlling the pressure of the pressure chamber corresponding to the minimum film thickness value so that the average film thickness of the substrate corresponding to the pressure chamber corresponding to the minimum film thickness value is greater than the average film thickness of the entire substrate.

[0022] In one embodiment, 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 while the substrate is being polished. In one aspect, the polishing rate during polishing is calculated from the film thickness of the substrate, and the amount of change in the film thickness of the substrate between the acquisition time when the film thickness of the substrate is acquired at each measurement point on the substrate and a reference time is calculated based on the polishing rate, and the film thickness of the substrate obtained during polishing of the substrate at the time interval is corrected using the amount of change as a correction value, and the maximum film thickness value and the minimum film thickness value are identified based on the corrected film thickness of the substrate.

[0023] In one aspect, 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, 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 average film thickness value of the entire 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 average film thickness value of the entire substrate, is determined in advance by recipe setting. In one aspect, 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 the overall average film thickness value of the substrate is compared with a second difference between the minimum film thickness value and the overall average film thickness value of the substrate, and when the first difference is greater than the second difference, the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is greater than the overall average film thickness value of the substrate. below When the second difference is greater than the first difference, the pressure in 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 average film thickness value of the entire substrate. In one aspect, 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 the average film thickness value in the pressing area 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 the pressing area corresponding to the minimum film thickness value, and 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, and 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 is higher than the average film thickness value of the entire substrate. [Effects of the Invention]

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

[0025] [Figure 1] FIG. 1 is a schematic diagram illustrating an embodiment of a polishing apparatus. [Figure 2] FIG. 2 is a cross-sectional view of the polishing head. [Figure 3] FIG. 10 is a diagram illustrating an example of a spectrum generated by an operation control unit. [Figure 4] FIG. 10 illustrates an example process for relating a reference spectrum to a corresponding film thickness. [Figure 5] 1A to 1C are diagrams illustrating an example of a process for polishing a wafer to be polished. [Figure 6] FIG. 1 shows a wafer divided into multiple pressing regions. [Figure 7] FIG. 10 shows a notch detection device. [Figure 8] 8(a) and 8(b) are diagrams showing the path of movement of the film thickness sensor across the surface of the wafer. [Figure 9]9(a) and 9(b) are diagrams for explaining the effect of the polishing step according to this embodiment. [Figure 10] FIG. 10 is a diagram showing a flow of pressure control in a pressure chamber by an operation control unit. [Figure 11] 10A and 10B are diagrams for explaining the effect of a polishing step according to another embodiment. [Figure 12] FIG. 10 is a diagram showing a flow of correcting a film thickness value by an operation control unit. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic diagram showing one embodiment of a polishing apparatus. As shown in Fig. 1, the polishing apparatus includes 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 against the polishing pad 2, a table motor 6 that rotates the polishing table 3, a polishing liquid supply nozzle 5 that supplies 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) that measures the film thickness of the wafer W, and an operation control unit 9 that controls the operation of the polishing apparatus. The upper surface of the polishing pad 2 forms a polishing surface 2a that polishes the wafer W.

[0027] The polishing head 1 is connected to a head shaft 10, and the head shaft 10 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 a table motor 6, and the table motor 6 is configured to rotate the polishing table 3 and 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 directions indicated by the arrows in Figure 1, a polishing liquid is supplied from a polishing liquid 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 the polishing head 1 presses the wafer W against the polishing surface 2a of the polishing pad 2 with the polishing liquid present on the polishing pad 2. The polishing table 3 rotates around its center CP. The surface of the wafer W is polished by the chemical action of the polishing liquid and the mechanical action of the abrasive grains contained in the polishing liquid or the polishing pad 2.

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

[0030] The operation control unit 9 is electrically connected to the film thickness sensor 40. In this embodiment, the film thickness sensor 40 guides light to the surface of the wafer W, detects the light reflected from the wafer W, and outputs a signal corresponding to the film thickness of the wafer W to the operation control unit 9. The operation 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 light reflected from the wafer W).

[0031] In this embodiment, the film thickness sensor 40 is an optical film thickness sensor, but may be any other film thickness sensor as long as it can measure the film thickness of the wafer W by the operation control unit 9. 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. As an example, the film thickness sensor 40 may be an eddy current sensor. The eddy current sensor detects an eddy current corresponding to the film thickness of the wafer W by passing a magnetic flux through the conductive film of the wafer W with its sensor coil, and outputs 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 spectroscope 47, and an optical sensor head 7 connected to the light source 44 and the spectroscope 47. The optical sensor head 7, the light source 44, and the spectroscope 47 are attached to the polishing table 3 and rotate integrally with the polishing table 3 and the polishing pad 2. The optical sensor head 7 is positioned so that it crosses the surface of the wafer W on the polishing pad 2 every time the polishing table 3 and the polishing pad 2 rotate once.

[0033] The storage device 9a stores therein 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 by 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 spectroscope 47. The spectroscope 47 separates the reflected light according to 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] 2 is a cross-sectional view of the polishing head 1. As shown in Fig. 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 disposed below the head body 21, and an annular retainer ring 60 fixed to the underside 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 retaining ring 60 are configured to rotate integrally with the rotation of the head shaft 10. The retaining ring 60 and drive ring 62 are configured to be movable up and down relative to the head body 21. The head body 21 is made of resin such as engineering plastic (e.g., PEEK).

[0036] The lower surface of the elastic membrane 65 forms 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 disposed so as 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 membrane 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.

[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, and the other pressure chambers 71, 72, and 73 are annular. These pressure chambers 70, 71, 72, and 73 are arranged (divided) concentrically. In this embodiment, the elastic membrane 65 forms four pressure chambers 70 to 73, but the number of pressure chambers described above is an example and may be changed as appropriate.

[0039] Gas transfer lines F1, F2, F3, and F4 are connected to the pressure chambers 70, 71, 72, and 73, respectively. One end of the 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 apparatus is installed. Compressed gas, such as compressed air, is supplied to the pressure chambers 70, 71, 72, and 73 through the gas transfer lines F1, F2, F3, and F4. When the compressed gas is supplied to the pressure chambers 70 to 73, the elastic membrane 65 expands, and the compressed gas in the pressure chambers 70 to 73 presses the wafer W against the polishing surface 2a of the polishing pad 2 via the elastic membrane 65. The 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 that is disposed around the elastic membrane 65 and that comes into contact with the polishing surface 2a of the polishing pad 2. The retainer ring 60 is disposed so as to surround the peripheral edge of the wafer W, and prevents the wafer W from flying out of the polishing head 1 while the wafer W is being polished.

[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 retaining ring pressing device 80 includes an annular piston 81 fixed to the top of the drive ring 62, and an annular rolling diaphragm 82 connected to the top surface of the piston 81. A retaining ring pressure chamber 83 is formed inside the rolling diaphragm 82. This retaining 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 retaining ring pressure chamber 83 through the gas transfer line F5.

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

[0044] The gas transfer lines F1, F2, F3, F4, and F5 extend via a rotary joint 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 the pressure chambers 70-73 and the retaining ring pressure chamber 83 through the pressure regulators R1-R5. The pressure regulators R1-R5 are configured to adjust the pressure of the compressed gas in the pressure chambers 70-73 and the retaining ring pressure chamber 83. The pressure regulators R1-R5 are connected to the operation control unit 9.

[0045] The pressure regulators R1 to R5 can independently change the internal pressures of the 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, i.e., the center, inner intermediate portion, outer intermediate portion, and edge portion, and the pressing force of the retainer ring 60 against the polishing pad 2. The gas transfer lines F1, F2, F3, F4, and F5 are also connected to atmospheric release valves (not shown), allowing the pressure chambers 70 to 73 and the retainer ring pressure chamber 83 to be opened to the atmosphere. In this embodiment, the elastic membrane 65 forms four pressure chambers 70 to 73, but in another embodiment, the elastic membrane 65 may form fewer or more than four pressure chambers.

[0046] Figure 3 shows an example of a spectrum generated by the operation 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 that indicates 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, unnecessary noise such as variations in intensity inherent to the optical system of the device or the light source can be removed from the measured intensity.

[0047] The reference intensity is the intensity of light measured in advance for each wavelength, and the relative reflectance is calculated for each wavelength. Specifically, the relative reflectance is calculated 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 spectrum of the reflected light from the reflected light intensity measurement data. The spectrum of the reflected light is expressed as a line graph (i.e., a 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 light-blocking conditions) from the measured intensity, and the corrected standard intensity is obtained by subtracting the dark level from the standard intensity.The corrected measured intensity is then divided by the corrected standard intensity to obtain the relative reflectance. Specifically, the relative reflectance R(λ) can be obtained using the following equation (1):

number

[0050] The operation control unit 9 generates a spectrum as shown in FIG. 3 from the intensity measurement data of the reflected light. Furthermore, the operation control unit 9 determines the film thickness of the wafer W from the spectrum of the reflected light. The spectrum of the reflected light changes according to the film thickness of the wafer W. Therefore, the operation control unit 9 can determine the film thickness of the wafer W from the spectrum of the reflected light. 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 operation control unit 9 is configured to determine the film thickness from a comparison between the measured spectrum (i.e., the measured data) and a plurality of reference spectra (i.e., the reference data). The operation control unit 9 compares the measured spectrum generated during polishing with the plurality of reference spectra to determine the reference spectrum having the closest shape to the measured spectrum, and obtains the film thickness associated with the determined reference spectrum. The reference spectrum having the closest shape to the measured spectrum is the spectrum having the smallest difference in relative reflectance between the reference spectrum and the measured spectrum.

[0052] The multiple reference spectra are obtained in advance by polishing a reference wafer having the same or a similar 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 wafer different from the reference wafer, and is a wafer on which a film thickness planarization process is performed. The reference wafer is a wafer on which a process of relating the reference spectrum to the corresponding film thickness is performed. Each reference spectrum can be associated with the film thickness at the time the reference spectrum was obtained. In other words, each reference spectrum was obtained at a different film thickness, and the 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] FIG. 4 is a diagram showing an example of a process for relating a reference spectrum to a corresponding film thickness. First, a reference wafer having the same or equivalent film thickness as wafer W is prepared. The reference wafer is transferred to film thickness measuring instrument 170 (see FIG. 1), and the initial film thickness of the reference wafer is measured by film thickness measuring instrument 170 (see step S101). Film thickness measuring instrument 170 is electrically connected to operation control unit 9. Operation control unit 9 determines a reference position for acquiring a reference spectrum over a wide film thickness range based on the film thickness (distribution) of the reference wafer measured by film thickness measuring instrument 170 (see step S102).

[0054] In this way, the operation control unit 9 obtains information about a specific position that is a portion on the circumference of the reference wafer from the film thickness measuring device 170. The film thickness measuring device 170 may be disposed inside the polishing apparatus. In this case, the film thickness measuring device 170 constitutes a component of the polishing apparatus. In one embodiment, the film thickness measuring device 170 may be disposed 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 operation control unit 9 determines a maximum film thickness position where the maximum film thickness value is obtained (i.e., a location where the film thickness of the reference wafer is thick) and a minimum film thickness position where the minimum film thickness value is obtained (i.e., a location where the film thickness of the reference wafer is thin), and determines either the maximum film thickness position or the minimum film thickness position as the reference position. In one embodiment, the operation 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 a maximum film thickness value and a 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 slurry as a polishing liquid is supplied to the polishing pad 1 (see step S103). During polishing of the reference wafer, light is irradiated onto the surface of the reference wafer, and the spectrum of the reflected light from the reference wafer (i.e., the reference spectrum) is acquired (see step S104).

[0058] The operation control unit 9 acquires a reference spectrum at each measurement point on the reference wafer every time the polishing table 3 makes one rotation. The operation control unit 9 controls at least one of the rotation speed of the polishing head 1 and the rotation speed of the polishing table 3 so that the film thickness sensor 40 passes over a reference position on the reference wafer during polishing. Through such control, the film thickness sensor 40 detects reflected light at the reference position, and the operation control unit 9 acquires a reference spectrum including the reference position.

[0059] The operation control unit 9 can acquire reference spectra over a wide range of film thickness values ​​by acquiring a reference spectrum including the reference position. Therefore, the operation control unit 9 can more reliably determine a reference spectrum whose shape is closest to the measured spectrum generated during polishing, and as a result, can measure (acquire) the film thickness of wafers W having various film thicknesses.

[0060] The reference spectrum is acquired every time the polishing table 3 makes one rotation. Therefore, multiple reference spectra are acquired while the reference wafer is being polished. After polishing of the reference wafer is completed, the reference wafer is again transferred 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] When 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 with each rotation of the polishing table 3, so the polishing time when 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 (linked) to a corresponding film thickness. Therefore, the operation control unit 9 can determine the reference spectrum having the shape closest to the measured spectrum during polishing of the wafer W, and thereby determine the current film thickness of the wafer W from the film thickness associated with the reference spectrum.

[0063] 5 is a diagram showing an example of a 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 position that is a part on the circumference of the wafer W. Therefore, as shown in step S201 of FIG. 5, the wafer W is transferred to the film thickness measuring instrument 170, and the initial film thickness of the wafer W is measured by the film thickness measuring instrument 170.

[0064] Thereafter, similarly to step S102 in FIG. 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 a maximum film thickness position where the maximum film thickness value is obtained (i.e., a location where the film thickness of the wafer W is thick) and a minimum film thickness position where the minimum film thickness value is obtained (i.e., a location where the film thickness of the wafer W is thin), 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 a maximum film thickness value and a minimum film thickness value based on the film thickness of the wafer W measured before polishing, calculate the difference between the average film thickness value of the entire wafer W and the maximum film thickness value, and the difference between the average film thickness value of the entire 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 the specific position.

[0067] The operation control unit 9 acquires film thickness distribution information of the wafer W measured by the film thickness measuring device 170, and determines the specific position of the wafer W. In one embodiment, when the film thickness measuring device 170 is disposed 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 the specific position of the wafer W, the operation control unit 9 starts polishing the wafer W (see step S203). During this polishing, light is irradiated onto the surface of the wafer W, and the operation control unit 9 acquires the spectrum of the reflected light from the wafer W (i.e., the measured spectrum). The operation control unit 9 determines a reference spectrum having a shape closest to the acquired measured spectrum, and acquires the film thickness associated with the determined reference spectrum (see step S204).

[0069] The operation control unit 9 controls the pressure regulators R1, R2, R3, and R4 to adjust the pressing force against the polishing surface 2a of the wafer W based on the film thickness of the wafer W. In this embodiment, the operation control unit 9 divides the area on the wafer W into a plurality of pressing areas A1, A2, A3, and A4 corresponding to a plurality of pressure chambers 70, 71, 72, and 73 (see FIG. 6).

[0070] 6 is a diagram showing a wafer divided into multiple pressing regions. In FIG. 6, the area 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 pressing regions A2 to A4 each have 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 FIG. 6, a specific position IP exists in the pressing area A4 of the wafer W. In the embodiment shown in FIG. 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 a control target area CA including the specific position IP. Furthermore, if an area of ​​a certain size including the specific position IP is set as the control target area, the film thickness uniformity adjustment described below can be performed stably. In this embodiment, the control target area CA is determined within a range in the circumferential direction (i.e., a range belonging to any of the areas A1 to A4). In one embodiment, when the specific position IP is a single point on the wafer W, the control target area CA may also be a single point on the wafer W.

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

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

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

[0075] Assuming that the wafer W does not shift circumferentially relative to the polishing head 1, the mounting angle of the wafer W relative to the polishing head 1 at the start of polishing is kept constant at all times, and the operation control unit 9 identifies the notch position Nt and determines the position of the control target area CA by grasping the rotation angle of the polishing head 1 using the rotary encoder 152 (see FIG. 7). Even without identifying the position of the notch position Nt, it is possible to determine the position of the control target area CA from the rotation angle of the polishing head 1, because the positional relationship between the notch position Nt and the control target area CA is determined in advance.

[0076] On the other hand, the wafer W may shift in the circumferential direction relative to the polishing head 1 due to 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, so the operation control unit 9 identifies the notch position Nt of the wafer W in real time while the wafer W is being polished, and determines the position of the control target area CA based on the notch position Nt.

[0077] FIG. 7 is a diagram showing a notch detection device. As shown in FIG. 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 be composed of a sensor such as an eddy current sensor, an optical sensor, or an image sensor. In the embodiment shown in FIG. 7, the notch detection device 151 is disposed 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) protrudes from the polishing pad 2, and rotates the wafer W.

[0078] The notch detector 151 detects the notch position Nt of the wafer W rotating while protruding from the polishing pad 2, and outputs a detection signal to the operation controller 9. The rotary encoder 152 detects a signal corresponding to the rotation angle of the polishing head 1, and outputs the detection signal to the operation controller 9. In this manner, the operation controller 9 obtains the relationship between the notch position Nt and the rotation angle of the polishing head 1, and can determine the relative angle between the notch position Nt and the polishing head 1 in real time. In one embodiment, the operation controller 9 may identify 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 detector.

[0079] 8(a) and 8(b) are diagrams showing the movement path of the film thickness sensor 40 across the surface of the wafer. In FIGS. 8(a) and 8(b), the movement path of the film thickness sensor 40 is indicated by five dotted lines. In the embodiment shown in FIGS. 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] 8(a) and 8(b), the operation control unit 9 can control the movement path of the film thickness sensor 40 by controlling at least one of the rotation speed of the polishing head 1 and the rotation speed of the polishing table 3. Therefore, the operation control unit 9 controls at least one of the rotation speed of the polishing head 1 and the rotation speed of the polishing table 3 based on the 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 operation control unit 9 can determine the movement path of the film thickness sensor 40 by determining the rotational speed ratio between the rotational speed of the polishing head 1 and the rotational speed of the polishing table 3. The rotational speed ratio in the embodiment shown in FIG. 8(a) is different from the rotational speed ratio in the embodiment shown in FIG. 8(b). Therefore, when the relative angle between the notch position Nt and the polishing head 1 is changed, the operation control unit 9 determines the rotational speed ratio between the rotational speed of the polishing head 1 and the rotational speed of the polishing table 3 so that the film thickness sensor 40 crosses a specific position IP on the surface of the wafer W.

[0082] In this way, the operation control unit 9 measures the film thickness in the control target area CA including the 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 area CA by controlling the pressure regulators R1 to R4 based on the measured film thickness.

[0083] 5, the operation control unit 9 controls the pressure in the pressure chambers 70-73 of the polishing head 1 corresponding to the specific position IP (or the control target area CA) so as to reduce the difference between the control target film thickness value and the overall average film thickness value of the wafer W. In the embodiment shown in FIG. 6, the control target area CA is located at a position on the wafer W corresponding to the pressing area A4, and the area 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 pressure regions A1 to A4 on the wafer W, which are divided according to the multiple pressure chambers 70 to 73, into a specific pressure region including the specific position IP and other pressure regions excluding the specific pressure region. In this embodiment, the specific pressure region corresponds to the pressure region A4, and the other pressure regions correspond to the pressure regions A1 to A3.

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

[0086] 9(a) and 9(b) are diagrams illustrating the effect of the polishing process according to this embodiment. Fig. 9(a) shows the profile of the average film thickness of the wafer W before and after polishing in a polishing process as a comparative example, and Fig. 9(b) shows the profile of the average film thickness of the wafer W before and after polishing in a polishing process according to this embodiment. In each of Figs. 9(a) and 9(b), the horizontal axis represents the distance from the center CPW of the wafer W, and the vertical axis represents the film thickness of the wafer W. In Figs. 9(a) and 9(b), the film thickness of the wafer W is represented as a box-and-whisker plot, with the film thickness at each measurement point within the pressing regions A1 to A4.

[0087] 9(a), in the film thickness of the wafer W before polishing, the minimum film thickness value in the pressure region A3 is particularly smaller (or thinner) than the film thicknesses in the other pressure regions A1, A2, and A4. Furthermore, the maximum film thickness value in the pressure region A4 is particularly larger (or thicker) than the film thicknesses in the other pressure regions A1, A2, and A3. In the comparative polishing process, the operation control unit 9 calculates the average film thickness value in each of the pressure regions A1 to A4 and the average film thickness value of the entire wafer W based on the signal detected by the film thickness sensor 40. Therefore, since the operation control unit 9 calculates the average film thickness value for each of the pressure regions A3 and A4, the difference between the average film thickness value for each of the pressure regions A1 and A2 and the average film thickness value for each of the pressure regions A3 and A4 may be small.

[0088] Even in such a case, the operation control unit 9 polishes the wafer W by controlling the pressure in each of the pressure chambers 70 to 73 so as to reduce the difference between the average film thickness value in each of the pressing regions A1 to A4 and the average film thickness value of the entire wafer W. Therefore, in the polished wafer W, the film thickness over the entire 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 the specific pressure region with a pressure different from that of the other pressure regions. More specifically, the operation control unit 9 controls the pressure in the pressure chambers 72 and 73 so as to reduce the difference between the control target film thickness value in each of the specific pressure regions A3 and A4 and the overall average film thickness value of the wafer W, and controls the pressure in each of the pressure chambers 70 and 71 so as to reduce the difference between the average film thickness value in each of the other pressure regions A1 and A2 and the overall average film thickness value of the wafer W. As shown in FIG. 9(b), the operation control unit 9 may determine multiple specific pressure regions and individually control the pressure in the determined multiple specific pressure regions.

[0090] In the embodiment shown in FIG. 9(b), the control target film thickness value in the pressing region A3 is smaller than the average film thickness value, so the pressure in the pressure chamber 72 is reduced compared to the pressure in the comparative example. As a result, the polishing amount in the pressing region A3 is smaller overall compared to the polishing amount in the comparative example. Because the control target film thickness value in the 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 polishing amount in the pressing region A4 is larger overall compared to the polishing amount in the comparative example. With this configuration, the polishing head 1 can keep the film thickness at the thickest point and the film thickness at the thinnest point across the wafer W within the desired tolerance range (see FIG. 9(b)). As a result, the uniformity of the film thickness across the wafer W can be improved.

[0091] In the above-described embodiment, the polishing head has multiple pressure chambers (air bags), but the technical concept of the present invention can be applied to any polishing head having concentrically arranged pressure elements. The pressure applied to the substrate by the concentrically arranged pressure elements is controlled based on the control target film thickness value in the control target region including the specific position. The pressure element can be, for example, a piezoelectric element.

[0092] In the above-described embodiment, a method is used in which the film thickness is estimated by determining a reference spectrum whose shape is closest to the measured spectrum, but the film thickness may also be estimated using other algorithms.

[0093] In the above-described embodiment, 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] 10 is a diagram showing a pressure control flow in the pressure chamber by the operation control unit. As shown in step S301 of FIG. 10, the operation control unit 9 identifies the maximum film thickness value and the minimum film thickness value from the entire film thickness of the wafer W obtained by the film thickness sensor 40 during polishing of the wafer W. More specifically, the operation control unit 9 identifies the maximum film thickness value and the minimum film thickness value over the entire wafer W from the signal output from the film thickness sensor 40.

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

[0096] 10, the operation control unit 9 determines whether the difference between the maximum film thickness value and the minimum film thickness value (i.e., film thickness range) over the entire wafer W is within a desired (predetermined) allowable range. If the film thickness range is within the allowable range (see "YES" in step S302), the operation control unit 9 controls the pressure in each pressure chamber by controlling each pressure regulator so as to reduce the difference between the average film thickness value in each pressing region and the average film thickness value over the entire wafer W (see step S303).

[0097] If the film thickness range is outside the allowable range (see "NO" in step S302), the operation control unit 9 identifies at least one of the pressure chamber 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 of the pressure chamber associated with the maximum film thickness value, the operation control unit 9 controls the pressure of the pressure chamber (see step S305A) so that the average film thickness value of the wafer W corresponding to the target pressure chamber is lower than the average film thickness value of the entire wafer W. When controlling the pressure of the pressure chamber associated with the minimum film thickness value, the operation control unit 9 controls the pressure of the pressure chamber (see step S305B) so that the average film thickness value of the wafer W corresponding to the target pressure chamber is higher than the average film thickness value of the entire wafer W.

[0099] Specifically, when controlling the pressure of the pressure chamber associated with 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 of the target pressure chamber so that the average film thickness value of the pressing region to which the measurement point of the maximum film thickness value belongs approaches the target film thickness value. More specifically, if the average film thickness value of the pressing region to which the measurement point of the maximum film thickness value belongs exceeds the target film thickness value, the operation control unit 9 increases the pressure of the pressure chamber associated with the pressing region to which the measurement point of the maximum film thickness value belongs.

[0100] To narrow the film thickness range, the operation control unit 9 may control only the pressure in the pressure chamber associated with the maximum film thickness value as described above, or may control only the pressure in the pressure chamber associated with the minimum film thickness value as described above, or may control both the pressure in the pressure chamber associated with the maximum film thickness value and the pressure in the pressure chamber associated with the minimum film thickness value as described above. Note that with regard to the other pressure chambers, the operation control unit 9 controls the other pressure chambers so as to reduce the difference between the average film thickness value of the corresponding pressing region and the average film thickness value of the entire wafer W.

[0101] With this configuration, when the film thickness range is outside the allowable range, the polishing amount of the pressing area corresponding to the maximum film thickness value or the polishing rate within a certain period of time becomes larger than when the present invention is not applied, and the polishing amount of the pressing area corresponding to the minimum film thickness value or the polishing rate within a certain period of time becomes smaller than when the present invention is not applied. As a result, the polishing head 1 can keep the difference between the film thickness at the thickest point and the film thickness at the thinnest point on the entire wafer W within the desired allowable range.

[0102] 11 is a diagram illustrating the effect of a polishing process according to another embodiment. In the embodiment shown in FIG. 11, the maximum and minimum film thicknesses in the pressure regions A1 and A2 are within the allowable range during polishing of the wafer W. Therefore, the operation control unit 9 controls the pressures in the pressure chambers 70 and 71 corresponding to the pressure regions A1 and A2, respectively, so as to reduce the difference between the average film thickness in each of the pressure regions A1 and A2 and the average film thickness of the entire wafer W.

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

[0104] Because the maximum film thickness value in the pressing area A4 is outside the allowable range, the operation control unit 9 controls the pressure in the pressure chamber 73 so that the average film thickness value in the pressing area A4 is lower than the average film thickness value of the entire wafer W. As a result, the amount of polishing in the pressing area A4 increases, and the polishing head 1 can keep the film thickness in the pressing area A4 within the allowable 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 while the wafer W is being polished, without measuring the film thickness of the wafer W in advance.

[0106] In addition, if the film thickness range is still outside the allowable range even in the pressure areas on the wafer W excluding the pressure areas on the wafer W corresponding to the maximum film thickness value and the pressure areas on the wafer W corresponding to the minimum film thickness value, the operation control unit 9 may perform pressure control of the pressure areas 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 polishing of the wafer W. For example, when the rotation speed ratio between the polishing table 3 and the polishing head 1 (rotation speed of the polishing table 3 / rotation speed of the polishing head 1) is 100 / 90 min -1 In this case, the polishing table 3 rotates 10 times more than the polishing head 1 in 60 seconds.

[0108] With the above rotational 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. Because 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. In this way, the operation control unit 9 may identify the maximum film thickness value and the minimum film thickness value 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 identify the maximum film thickness value and the minimum film thickness value in each of the multiple pressing areas A1, A2, A3, and A4 each time the polishing table 3 rotates (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 polishing at the controlled (adjusted) pressure progresses and is reflected in a 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 film thickness measurement results obtained within a certain period of time and the pressure of the associated pressure chamber is adjusted accordingly too frequently, there is a possibility that the pressure responsiveness of the elastic membrane may not be properly controlled. Therefore, it is desirable for the operation control unit 9 to check the next film thickness range at certain intervals, leaving a period of time for the effect of the pressure chamber pressure adjustment to become apparent. Furthermore, the operation control unit 9 may measure the film thickness at the same measurement point again after adjusting the pressure to confirm the results of the pressure adjustment.

[0112] When the operation control unit 9 determines the maximum and minimum film thickness values, the polishing table 3 and polishing head 1 are constantly rotating, and polishing of the wafer W is constantly in progress. Therefore, for example, if the time interval is determined to be 6 seconds, in the relationship between the film thickness of the wafer W acquired at 1 second and the film thickness of the wafer W acquired at 5 seconds, the operation control unit 9 will determine the film thickness acquired at 5 seconds to be thinner than the film thickness acquired at 1 second, making it impossible to accurately evaluate the uniformity of the actual film thickness. Therefore, the operation control unit 9 is configured to correct the film thickness value of the wafer W at each acquisition timing based on the polishing speed of the wafer W.

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

[0114] The operation control unit 9 corrects the film thickness of the wafer W obtained during polishing at a fixed time interval using the amount of change in film thickness as a correction value (see step S403). For example, if the predetermined reference time is set to the start time of the time interval, i.e., 0 seconds, the film thickness of the wafer W gradually decreases from the reference time, and therefore the operation control unit 9 corrects the film thickness of the wafer W by adding the amount of 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 time interval (6 seconds in the above-described embodiment), the film thickness of the wafer W will be measured to be thicker than the film thickness at the reference time, and therefore the operation control unit 9 subtracts the amount of change in film thickness as a correction value from the film thickness of the wafer W obtained during polishing, thereby correcting the film thickness of the wafer W. It is arbitrarily determined whether the reference time is set to the start time of the time interval or a time in between.

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

[0117] In the above-described embodiment, the case where the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are separate (or different) pressure chambers has been described, but the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value may be the same pressure chamber. In this case, the operation control unit 9 may determine in advance by setting the polishing recipe whether to control the pressure of the target pressure chamber so that the average film thickness value of the wafer W corresponding to that pressure chamber is lower than the average film thickness value of the entire wafer W, or to control the pressure of the target pressure chamber so that the average film thickness value of the wafer W corresponding to that pressure chamber is higher than the average film thickness value of the entire wafer W.

[0118] In one embodiment, 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, 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 may compare the first difference with the second difference, and if the first difference is greater than the second difference, control the pressure of 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 of 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 above-described embodiment, the difference between the maximum film thickness value and the average film thickness value of the entire wafer W is defined as the first difference, and the difference between the minimum film thickness value and the average film thickness value of the entire wafer W is defined as the second difference. However, the difference between the maximum film thickness value and the average film thickness in the pressing area corresponding to the maximum film thickness value may be defined as the first difference, and the difference between the minimum film thickness value and the average film thickness in the pressing area corresponding to the minimum film thickness value may be defined as the second difference.

[0121] In the above-described embodiment, the operation control unit 9 determines whether the difference between the maximum and minimum film thickness values ​​(film thickness range) is within a desired (predetermined) allowable range, and if it is outside the allowable range, adjusts the pressure in the pressure chamber associated with the maximum film thickness value and / or the pressure chamber associated with the minimum film thickness value. In one embodiment, the operation control unit 9 may adjust the pressure in the pressure chamber associated with the maximum film thickness value and / or the pressure chamber associated with the minimum film thickness value without comparing the difference between the maximum and minimum film thickness values ​​with the allowable range. In this manner, the pressure in the pressure chamber is controlled so that the average film thickness value in the pressure region associated with the maximum film thickness value is lower than the average film thickness value of the entire wafer W, and the pressure in the pressure chamber is controlled so that the average film thickness value in the pressure region associated with the minimum film thickness value is higher than the average film thickness value of the entire wafer W. As a result, the difference between the maximum and minimum film thickness values ​​is reduced, and the film thickness uniformity on the wafer W can be improved.

[0122] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims. [Explanation of symbols]

[0123] 1 polishing head 2 polishing pads 2a Polished surface 3 Polishing table 5 Polishing liquid supply nozzle 6 Table Motor 7 Optical sensor head 9. Operation control section 9a Storage device 9b Arithmetic unit 10 Head shaft 21 Head body 40 Film Thickness Sensor 44 Light source 47 Spectrometer 60 Retainer ring 60a Bottom 60b top surface 62 Drive Ring 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 Measuring Instrument

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 that outputs a signal corresponding to the 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 acquiring information about a specific position that is a portion on the 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 for the entire substrate; a polishing apparatus that controls the pressure in the pressure chamber of the polishing head corresponding to the specific position so as to reduce the difference between the control target film thickness value and the average film thickness value of the entire substrate.

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

3. The operation control unit determining a maximum film thickness position where a maximum film thickness value is obtained and a minimum film thickness position where 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 determining a maximum film thickness value and a minimum film thickness value based on the film thickness of the substrate measured before polishing; calculating a difference between the average film thickness value of the entire substrate and the maximum film thickness value, and a difference between the average film thickness value of 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 largest difference in film thickness value is obtained is determined as the specific position.

5. 5. A polishing apparatus according to claim 1, 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 the 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 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, wherein the pressure in the pressure chamber of the polishing head corresponding to the specific position is controlled based on the measured film thickness.

8. The operation control unit 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; 8. The polishing apparatus according to claim 1, wherein the pressure in the pressure chamber corresponding to the other pressing region is controlled so as to reduce the difference between the average film thickness value of the other pressing region and the average film thickness value of the entire substrate.

9. The operation control unit obtaining information about a reference position that is a portion of a 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 a film thickness in a region on the substrate including the reference position; 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 the 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 determining a relative angle of the polishing head and a reference position of the substrate in the circumferential direction based on a relationship between the reference position and a rotation angle of the polishing head; 12. The polishing apparatus according to claim 11, wherein at least one of a rotation speed of the polishing head and a rotation speed of the polishing table is 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 into concentric circles, acquiring information about a specific position that is a portion on the 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 for the entire substrate; a polishing method for controlling 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.

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 where a maximum film thickness value is obtained and a minimum film thickness position where 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 the film thickness of the substrate measured before polishing; calculating a difference between the average film thickness value of the entire substrate and the maximum film thickness value, and a difference between the average film thickness value of the entire substrate and the minimum film thickness value; 15. The polishing method according to claim 13, wherein the position on the substrate where the largest difference in film thickness value 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 the 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 region including the specific position during polishing based on an output signal from a 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, wherein the pressure in the pressure chamber corresponding to the other pressing region is controlled so as to reduce a difference between the average film thickness value of the other pressing region and the average film thickness value of the entire substrate.

21. obtaining information about a reference position 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 a 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, wherein each of the plurality of data is associated 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, wherein at least one of the rotation speed of the polishing head and the rotation speed of the polishing table is controlled 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 of the polishing head and a reference position of the substrate in the circumferential direction based on a relationship between the reference position and a 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 that outputs a signal corresponding to the 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 Identifying a maximum film thickness value and a minimum film thickness value from the film thickness of the substrate obtained by the film thickness sensor during polishing of the substrate; Identifying at least one of a pressure chamber corresponding to a position on the substrate where the maximum film thickness value is detected and a pressure chamber corresponding to a position on 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 that 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 unit specifies 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 calculating a polishing rate during polishing from the film thickness of the substrate acquired by the film thickness sensor; calculating, based on the polishing rate, a change in the 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; correcting the film thickness of the substrate obtained during polishing of the substrate during the time interval using the amount of change 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 the corrected film thickness of the substrate.

28. 28. The polishing apparatus according to claim 25, wherein, 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, 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 average film thickness value of the entire 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 average film thickness value of the entire substrate.

29. The operation control unit 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, 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 average film thickness value of the entire substrate.

30. The operation control unit 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, a first difference between the maximum film thickness value and an average film thickness value in the pressing region corresponding to the maximum film thickness value is compared with a second difference between the minimum film thickness value and an 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 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 average film thickness value of the entire 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 into concentric circles, Identifying a maximum film thickness value and a minimum film thickness value from the film thickness of the substrate obtained during polishing of the substrate; Identifying at least one of a pressure chamber corresponding to a position on the substrate where the maximum film thickness value is detected and a pressure chamber corresponding to a position on 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 in which, when controlling the pressure of a pressure chamber associated with the minimum film thickness value, 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 average film thickness value of the entire substrate.

32. 32. The polishing method according to claim 31, wherein the maximum film thickness value and the minimum film thickness value are determined 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 a change in the film thickness of the substrate between an acquisition time when 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 the film thickness of the substrate obtained during polishing of the substrate during the time interval using the amount of change 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 determined based on the corrected film thickness of the substrate.

34. The polishing method according to any one of claims 31 to 33, wherein, 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, 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 average film thickness value of the entire 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 average film thickness value of the entire substrate.

35. 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, 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 average film thickness value of the entire substrate.

36. 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, a first difference between the maximum film thickness value and an average film thickness value in the pressing region corresponding to the maximum film thickness value is compared with a second difference between the minimum film thickness value and an 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 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 average film thickness value of the entire substrate.

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