Polishing method and polishing apparatus

Abstract

To provide a polishing method capable of preventing insufficient polishing and excessive polishing of a substrate.SOLUTION: The polishing method includes outputting a film-thickness monitoring signal corresponding to a thickness of the substrate W by the sensor 30 during polishing of the substrate W, and determining a polishing end point C1 in the area C2 and a polishing end point C2 in the area Tfin2 based on the film-thickness monitoring signal in each of the area Tfin1 and the area on the substrate W. C1, the polishing end point Tfin2 is a polishing end point after the polishing end point Tfin1, and when the polishing end point Tfin1 is reached, the pressure in the pressure chamber 40A is lowered to stop the progress of polishing of the region C1, and when the polishing end point Tfin2 is reached, the pressure in the pressure chamber 40B is lowered to stop the progress of polishing of the region C2.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a polishing method and a polishing apparatus for polishing a substrate such as a wafer. [Background technology]

[0002] In the semiconductor device manufacturing process, technology for planarizing the surface of semiconductor devices is becoming increasingly important. The most important of these planarization technologies is chemical mechanical polishing (CMP). This polishing process involves using a polishing device to supply a polishing solution containing abrasive particles such as silica (SiO2) onto the polishing surface of a polishing pad while pressing a substrate such as a wafer against the polishing surface with a polishing head.

[0003] In a polishing apparatus that performs such CMP, monitor signals related to the film thickness on the substrate are measured for each of a plurality of areas on the substrate while the substrate is being polished, and the film thickness profile (film thickness distribution) of the substrate being polished is monitored based on the measured monitor signals. Patent Document 1 discloses a polishing apparatus that controls the pressures in a plurality of pressure chambers of a polishing head so that monitor signals acquired in other areas converge to a reference signal, which is a monitor signal acquired in a reference area on the substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2008-503356 Summary of the Invention [Problem to be solved by the invention]

[0005] In the polishing apparatus described in Patent Document 1, the polishing endpoints of multiple areas on a substrate are uniformly determined based on the polishing endpoint of a reference area. However, due to differences in the surface structures and underlying structures of the multiple areas, the polishing endpoint of the reference area and the polishing endpoint of other areas (i.e., the point at which the target film thickness is reached) may differ. Therefore, if polishing is uniformly terminated when the polishing endpoint of the reference area is reached, over-polishing or under-polishing may occur in the other areas.

[0006] Therefore, the present invention provides a polishing method and a polishing apparatus that can prevent insufficient and excessive polishing of a substrate. [Means for solving the problem]

[0007] In one aspect, a polishing method is provided, which includes rotating a polishing table supporting a polishing pad, pressing a substrate against a polishing surface of the polishing pad using a first pressure chamber and a second pressure chamber of a polishing head, and polishing the substrate. During polishing of the substrate, a sensor outputs a film thickness monitoring signal corresponding to a film thickness of the substrate. Based on the film thickness monitoring signals in a first region and a second region on the substrate corresponding to the first pressure chamber and the second pressure chamber, a first polishing end point in the first region and a second polishing end point in the second region are determined. The second polishing end point is a polishing end point that is later than the first polishing end point. When the first polishing end point is reached, the pressure in the first pressure chamber is reduced to stop polishing of the first region. When the second polishing end point is reached, the pressure in the second pressure chamber is reduced to stop polishing of the second region.

[0008] In one aspect, determining the first polishing end point and the second polishing end point based on the film thickness monitoring signal in the first region and the second region, respectively, involves determining the first polishing end point as a point in time when the output value of the film thickness monitoring signal in the first region reaches a target signal value indicating a target film thickness, and determining the second polishing end point as a point in time when the output value of the film thickness monitoring signal in the second region reaches the target signal value. In one embodiment, stopping the progress of polishing of the first region by reducing the pressure in the first pressure chamber when the first polishing endpoint is reached means stopping the progress of polishing of the first region by opening the first pressure chamber to the atmosphere when the first polishing endpoint is reached. In one embodiment, the polishing method further includes increasing the pressure in the second pressure chamber when the first polishing endpoint is reached, thereby increasing the polishing rate in the second region. In one aspect, increasing the polishing rate in the second region by increasing the pressure in the second pressure chamber when the first polishing endpoint is reached includes calculating a compensation pressure value in the second pressure chamber based on an output value of a film thickness monitoring signal corresponding to the film thickness in the second region at the first polishing endpoint and a target signal value indicating a target film thickness when the first polishing endpoint is reached, and increasing the pressure in the second pressure chamber to the compensation pressure value, thereby increasing the polishing rate in the second region. In one aspect, determining the first polishing end point and the second polishing end point based on the film thickness monitoring signals in the first region and the second region, respectively, involves calculating a signal average value, which is an average value of output values ​​of a plurality of film thickness monitoring signals from a plurality of film thickness monitoring signals at a plurality of measurement points located in the first region and the second region, and determining the first polishing end point and the second polishing end point based on the signal average value in the first region and the second region, respectively.

[0009] In one embodiment, a polishing head includes a polishing table that supports a polishing pad, a table motor that rotates the polishing table, a polishing head having a first pressure chamber and a second pressure chamber for pressing a substrate against the polishing surface of the polishing pad, a first pressure regulator that adjusts the pressure in the first pressure chamber, a second pressure regulator that adjusts the pressure in the second pressure chamber, a sensor that outputs a film thickness monitoring signal corresponding to the film thickness of the substrate, and an operation control unit that controls the operations of the first pressure regulator and the second pressure regulator, and the operation control unit controls the operation of a first region and a second region on the substrate corresponding to the first pressure chamber and the second pressure chamber. a first polishing endpoint in the first region and a second polishing endpoint in the second region are determined based on the film thickness monitoring signal in each region, the second polishing endpoint being a polishing endpoint later than the first polishing endpoint, and when the first polishing endpoint is reached, a command is issued to the first pressure regulator to reduce the pressure in the first pressure chamber, thereby stopping the polishing of the first region; and when the second polishing endpoint is reached, a command is issued to the second pressure regulator to reduce the pressure in the second pressure chamber, thereby stopping the polishing of the second region.

[0010] In one aspect, the operation control unit is configured to determine the first polishing end point as a time point at which the output value of the film thickness monitoring signal in the first region reaches a target signal value indicating a target film thickness, and to determine the second polishing end point as a time point at which the output value of the film thickness monitoring signal in the second region reaches the target signal value. In one embodiment, the polishing apparatus further includes a first atmosphere release valve that opens the first pressure chamber to the atmosphere, and the operation control unit is configured to issue a command to the first atmosphere release valve instead of the first pressure regulator when the first polishing endpoint is reached, thereby opening the first pressure chamber to the atmosphere and stopping the progress of polishing of the first region. In one embodiment, the operation control unit is configured to issue a command to the first pressure regulator to reduce the pressure in a first pressure chamber of the polishing head corresponding to the first region when the first polishing endpoint is reached, thereby stopping the progress of polishing of the first region, and to issue a command to the second pressure regulator to increase the pressure in the second pressure chamber, thereby increasing the polishing rate in the second region. In one aspect, when the first polishing endpoint is reached, the operation control unit is configured to calculate a compensation pressure value in the second pressure chamber based on an output value of a film thickness monitoring signal corresponding to the film thickness of the second region at the first polishing endpoint and a target signal value indicating a target film thickness, and issue a command to the second pressure regulator to increase the pressure in the second pressure chamber to the compensation pressure value, thereby increasing the polishing rate in the second region. In one embodiment, the operation control unit is configured to calculate a signal average value, which is an average value of output values ​​of a plurality of film thickness monitoring signals from a plurality of measurement points located in each of the first region and the second region, and to determine the first polishing end point and the second polishing end point based on the signal average values ​​in each of the first region and the second region. [Effects of the Invention]

[0011] According to the present invention, the polishing endpoint for each of a plurality of regions on a substrate is determined, and when the polishing endpoint for each region is reached, the pressure in the corresponding pressure chamber is reduced to stop the polishing of that region. Therefore, polishing can be stopped at an appropriate polishing endpoint for each region on the substrate, preventing under-polishing and over-polishing of the substrate. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram illustrating an embodiment of a polishing apparatus. [Figure 2] FIG. 2 is a cross-sectional view showing one embodiment of a polishing head. [Figure 3]FIG. 2 is a schematic diagram showing an example of a plurality of measurement points on the surface of a substrate. [Figure 4] 1 is a cross-sectional view showing an example of a laminate structure of a substrate to be polished. [Figure 5] 10 is a graph showing an example of the relationship between the output value of a film thickness monitoring signal and polishing time in a plurality of regions of a substrate. [Figure 6] 10 is a graph showing an example of the relationship between the output value of the film thickness monitoring signal and the polishing time in a plurality of regions of a substrate according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing one embodiment of a polishing apparatus 1. The polishing apparatus 1 shown in Fig. 1 is an apparatus for chemically and mechanically polishing a substrate W such as a wafer. The polishing apparatus 1 includes a polishing pad 2, a polishing table 3 that supports the polishing pad 2, a table motor 6 that rotates the polishing table 3, a polishing head 10 that presses the substrate W against the polishing pad 2, and a polishing liquid supply nozzle 20 that supplies a polishing liquid (e.g., a slurry containing abrasive grains) onto the polishing pad 2.

[0014] The polishing pad 2 is attached to the upper surface of the polishing table 3. The surface of the polishing pad 2 forms a polishing surface 2a that polishes the substrate W. The polishing table 3 is connected to a table motor 6 via a table shaft 5. The table motor 6 is configured to rotate the polishing table 3 in the direction indicated by the arrow in FIG. 1. The polishing table 3 is rotated around its axis by the table motor 6. The polishing pad 2 rotates integrally with the polishing table 3.

[0015] The polishing head 10 is connected to the lower end of a polishing head shaft 12. The polishing head 10 is configured to hold a substrate W on its lower surface by vacuum suction. The polishing head 10 is connected to a polishing head motor (not shown) via the polishing head shaft 12. The polishing head motor is configured to rotate the polishing head 10 in the direction indicated by the arrow in FIG. 1. The polishing head 10 is rotated around its axis by the polishing head motor. The polishing head 10 rotates integrally with the polishing head shaft 12.

[0016] The polishing head 10 is connected to a polishing head lifting mechanism (not shown) via a polishing head shaft 12. The polishing head lifting mechanism is configured to lift and lower (move up and down) the polishing head 10. The polishing head 10 moves up and down relative to the polishing pad 2 by the polishing head lifting mechanism. The polishing head 10 moves up and down integrally with the polishing head shaft 12. The polishing head lifting mechanism lowers the polishing head 10 holding the substrate W toward the polishing pad 2, thereby bringing the surface of the substrate W (in other words, the surface to be polished) into contact with the polishing surface 2a of the polishing pad 2.

[0017] The polishing apparatus 1 further includes an operation control unit 50 that controls the operation of each component of the polishing apparatus 1. The operation control unit 50 includes a storage device 50a that stores a program and an arithmetic unit 50b that executes calculations according to instructions included in the program. The operation control unit 50 is composed of at least one computer. The storage device 50a includes a main storage device such as a random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD). Examples of the arithmetic unit 50b include a CPU (central processing unit) and a GPU (graphics processing unit). However, the specific configuration of the operation control unit 50 is not limited to these examples.

[0018] The polishing of the substrate W is performed as follows. The polishing head 10 holds the substrate W with its surface (surface to be polished) facing the polishing pad 2. While the polishing table 3 is rotated by the table motor 6, a polishing liquid is supplied from the polishing liquid supply nozzle 20 onto the polishing surface 2a of the polishing pad 2. In this state, the polishing head 10 is rotated by the polishing head motor and lowered by the polishing head lifting mechanism. As a result, the surface of the substrate W comes into contact with the polishing surface 2a of the polishing pad 2. Furthermore, the polishing head 10 presses the substrate W against the polishing pad 2. The surface of the substrate W is polished by the chemical action of the polishing liquid and the mechanical action of the abrasive grains contained in the polishing liquid and / or the polishing surface 2a.

[0019] Next, the polishing head 10 will be described in detail. Fig. 2 is a cross-sectional view showing one embodiment of the polishing head 10. The polishing head 10 includes a carrier 41 fixed to the end of the polishing head shaft 12, an elastic membrane 44 attached to the lower part of the carrier 41, and a retainer ring 42 disposed below the carrier 41. The retainer ring 42 is disposed around the elastic membrane 44. The retainer ring 42 is an annular structure that holds the substrate W to prevent it from flying out of the polishing head 10 while it is being polished.

[0020] The elastic membrane 44 includes a contact portion 45 having a contact surface 45a that can contact the upper surface of the substrate W, and inner wall portions 46a, 46b, 46c and an outer wall portion 46d connected to the contact portion 45. The contact portion 45 has substantially the same size and shape as the upper surface of the substrate W. The inner wall portions 46a, 46b, 46c and the outer wall portion 46d are endless walls arranged concentrically. The outer wall portion 46d is located outside the inner wall portions 46a, 46b, 46c and is arranged to surround the inner wall portions 46a, 46b, 46c. In this embodiment, three inner wall portions 46a, 46b, 46c are provided, but the number of inner wall portions is not limited to this embodiment. In an embodiment, one or two inner wall portions, or four or more inner wall portions may be provided.

[0021] A plurality of pressure chambers 40A, 40B, 40C, and 40D (four in this embodiment) are provided between the elastic membrane 44 and the carrier 41. The pressure chambers 40A, 40B, 40C, and 40D are formed by the contact portion 45 of the elastic membrane 44, inner wall portions 46a, 46b, and 46c, and an outer wall portion 46d. That is, the pressure chamber 40A is located within the inner wall portion 46a, the pressure chamber 40B is located between the inner wall portion 46a and the inner wall portion 46b, the pressure chamber 40C is located between the inner wall portion 46b and the inner wall portion 46c, and the pressure chamber 40D is located between the inner wall portion 46c and the outer wall portion 46d. The sizes of the pressure chambers 40A, 40B, 40C, and 40D, i.e., the distances from the center of the elastic membrane 44 to the inner wall portions 46a, 46b, and 46c and the outer wall portion 46d, are not particularly limited. For example, the inner wall portions 46a, 46b, 46c and the outer wall portion 46d may be arranged at different intervals from the center of the elastic membrane 44, or may be arranged at equal intervals.

[0022] The pressure chamber 40A located at the center of the elastic membrane 44 is circular, while the other pressure chambers 40B, 40C, and 40D are annular. These pressure chambers 40A, 40B, 40C, and 40D are arranged concentrically. Pressure chamber 40B is located outside pressure chamber 40A, pressure chamber 40C is located outside pressure chamber 40B, and pressure chamber 40D is located outside pressure chamber 40C. In this embodiment, the elastic membrane 44 forms four pressure chambers 40A to 40D, but in another embodiment, the elastic membrane 44 may form two or three pressure chambers, or may form five or more pressure chambers.

[0023] An annular membrane (rolling diaphragm) 47 is disposed between the carrier 41 and the retainer ring 42, and a pressure chamber 40E is formed inside this membrane 47. Gas transfer lines F1, F2, F3, F4, and F5 are connected to the pressure chambers 40A, 40B, 40C, 40D, and 40E, respectively. The gas transfer lines F1, F2, F3, F4, and F5 extend via a rotary joint 15 attached to the polishing head shaft 12.

[0024] Gas transfer lines F1, F2, F3, F4, and F5 are connected to gas supply lines La1, La2, La3, La4, and La5, respectively, upstream of rotary joint 15. Gas supply lines La1, La2, La3, La4, and La5 are connected to a compressed gas supply source (not shown) serving as a utility supply source provided in a factory in which polishing apparatus 1 is installed. Compressed gas such as compressed air is supplied from gas supply lines La1, La2, La3, La4, and La5 through gas transfer lines F1, F2, F3, F4, and F5 to pressure chambers 40A, 40B, 40C, 40D, and 40E, respectively.

[0025] Gas supply valves Va1, Va2, Va3, Va4, and Va5 and pressure regulators Ra1, Ra2, Ra3, Ra4, and Ra5 are attached to the gas supply lines La1, La2, La3, La4, and La5, respectively. The gas supply valves Va1, Va2, Va3, Va4, and Va5 are actuator-driven valves, such as solenoid valves, electric valves, or air-operated valves. In one embodiment, the gas supply valves Va1 to Va5 may be manual. When the gas supply valves Va1 to Va5 are opened, compressed gas from the compressed gas supply source is supplied independently into the pressure chambers 40A to 40E through the pressure regulators Ra1 to Ra5. The pressure regulators Ra1 to Ra5 ​​are configured to adjust the pressure of the compressed gas in the pressure chambers 40A to 40E.

[0026] The gas supply valves Va1 to Va5 and the pressure regulators Ra1 to Ra5 ​​are connected to the operation control unit 50. The operation of the gas supply valves Va1 to Va5 and the pressure regulators Ra1 to Ra5 ​​is controlled by the operation control unit 50. The operation control unit 50 sends target pressure values ​​for each of the pressure chambers 40A to 40E to the pressure regulators Ra1 to Ra5, and the pressure regulators Ra1 to Ra5 ​​operate to maintain the pressures in the pressure chambers 40A to 40E at the corresponding target pressure values.

[0027] The pressure regulators Ra1 to Ra5 ​​can change the internal pressures of the pressure chambers 40A to 40E independently of one another. Therefore, the polishing head 10 can independently adjust the polishing pressures for the four corresponding regions of the substrate W, namely, the center, inner middle, outer middle, and edge regions, and the pressing force of the retainer ring 42 against the polishing surface 2a of the polishing pad 2. For example, the polishing head 10 can press different regions of the surface of the substrate W against the polishing surface 2a of the polishing pad 2 with different polishing pressures. Therefore, the polishing apparatus 1 can polish different regions of the surface of the substrate W at different polishing rates.

[0028] Furthermore, gas transfer lines F1, F2, F3, F4, and F5 are connected to vacuum lines Lb1, Lb2, Lb3, Lb4, and Lb5, respectively, upstream of rotary joint 15. Compressed gas, such as compressed air, is supplied from gas supply lines La1, La2, La3, La4, and La5 through gas transfer lines F1, F2, F3, F4, and F5 to pressure chambers 40A, 40B, 40C, 40D, and 40E, respectively. Vacuum valves Vb1, Vb2, Vb3, Vb4, and Vb5 and vacuum regulators Rb1, Rb2, Rb3, Rb4, and Rb5 are attached to vacuum lines Lb1, Lb2, Lb3, Lb4, and Lb5, respectively. Vacuum valves Vb1, Vb2, Vb3, Vb4, and Vb5 are actuator-driven valves such as solenoid valves, electric valves, or air-operated valves. In one embodiment, the vacuum valves Vb1 to Vb5 may be manual.

[0029] When the vacuum valves Vb1 to Vb5 are opened, the compressed gas in the pressure chambers 40A to 40E is discharged independently from the pressure chambers 40A to 40E to the outside through the gas transfer lines F1 to F5 and the vacuum lines Lb1 to Lb5, respectively, creating a negative pressure in the pressure chambers 40A to 40E. The vacuum regulators Rb1 to Rb5 are configured to adjust the vacuum pressure in the pressure chambers 40A to 40E.

[0030] The vacuum valves Vb1-Vb5 and the vacuum regulators Rb1-Rb5 are connected to the operation control unit 50. The operation of the vacuum valves Vb1-Vb5 and the vacuum regulators Rb1-Rb5 is controlled by the operation control unit 50. When the polishing head 10 holds the substrate W, the vacuum valves Vb1, Vb2, and Vb3 are opened with the contact portion 45 of the elastic membrane 44 in contact with the substrate W, creating a vacuum in the pressure chambers 40A, 40B, and 40C. The portions of the contact portion 45 that form these pressure chambers 40A, 40B, and 40C are recessed upward, allowing the polishing head 10 to adsorb the substrate W due to the suction effect of the elastic membrane 44. Furthermore, when compressed gas is supplied to the pressure chambers 40A, 40B, and 40C to release the suction effect, the polishing head 10 can release the substrate W.

[0031] Furthermore, the gas transfer lines F1, F2, F3, F4, and F5 are connected to atmosphere release lines Lc1, Lc2, Lc3, Lc4, and Lc5, respectively, upstream of the rotary joint 15. The atmosphere release lines Lc1, Lc2, Lc3, Lc4, and Lc5 are respectively equipped with atmosphere release valves Vc1, Vc2, Vc3, Vc4, and Vc5. The atmosphere release valves Vc1, Vc2, Vc3, Vc4, and Vc5 are actuator-driven valves such as solenoid valves, motor-operated valves, and air-operated valves. In one embodiment, the atmosphere release valves Vc1 to Vc5 may be manually operated. When the atmosphere release valves Vc1 to Vc5 are opened, the pressure chambers 40A to 40E are independently opened to the atmosphere. The atmosphere release valves Vc1 to Vc5 are connected to an operation control unit 50. The operation of the atmosphere release valves Vc1 to Vc5 is controlled by the operation control unit 50. In one embodiment, the air release lines Lc1 to Lc5 and the air release valves Vc1 to Vc5 may not be provided.

[0032] In this embodiment, gas supply valves Va1-Va5, vacuum valves Vb1-Vb5, and atmosphere release valves Vc1-Vc5 are attached to gas supply lines La1-La5, vacuum lines Lb1-Lb5, and atmosphere release lines Lc1-Lc5, respectively, which are connected to pressure chambers 40A-40E via gas transfer lines F1-F5. In one embodiment, three-way valves may be attached to gas transfer lines F1-F5 instead of the gas supply valves Va1-Va5, vacuum valves Vb1-Vb5, and atmosphere release valves Vc1-Vc5. In this case, by operating the three-way valves, the lines connected to pressure chambers 40A-40E via gas transfer lines F1-F5 may be switched to any of gas supply lines La1-La5, vacuum lines Lb1-Lb5, and atmosphere release lines Lc1-Lc5.

[0033] 1, the polishing apparatus 1 further includes a sensor 30 that outputs a film thickness monitoring signal corresponding to the film thickness of the substrate W. The film thickness monitoring signal is a signal that directly or indirectly indicates the film thickness of the substrate W, and the output value of the film thickness monitoring signal changes according to the film thickness of the substrate W. The output value of the film thickness monitoring signal may be a value that represents the film thickness of the substrate W itself, or may be a physical quantity or signal value before being converted into film thickness.

[0034] Examples of the sensor 30 include an optical film thickness sensor and an eddy current sensor. The optical film thickness sensor is configured to irradiate the surface of the substrate W with light and output a film thickness monitoring signal that directly or indirectly indicates the film thickness of the substrate W from the spectrum of the light reflected from the substrate W. For example, the optical film thickness sensor determines a reference spectrum from a reference spectrum library that has a shape that is closest to the spectrum of the reflected light, and outputs a film thickness monitoring signal that indicates the film thickness associated with the determined reference spectrum. In another example, the optical film thickness sensor performs a Fourier transform on the spectrum of the reflected light and outputs a film thickness monitoring signal that indicates the film thickness calculated from the obtained frequency spectrum. In yet another example, the optical film thickness sensor outputs a film thickness monitoring signal that indicates the relative amount of change in the spectrum of the reflected light.

[0035] The eddy current sensor is configured to induce eddy currents in a conductive film formed on the substrate W and output a film thickness monitoring signal that varies in accordance with the impedance of an electric circuit including the conductive film and a coil of the eddy current sensor. Known devices can be used for the optical film thickness sensor and the eddy current sensor.

[0036] The sensor 30 is installed inside the polishing table 3 and rotates integrally with the polishing table 3. The sensor 30 is disposed at a predetermined distance from the center of the polishing table 3 in the radial direction of the polishing table 3. The sensor 30 is configured to output film thickness monitoring signals at multiple measurement points on the substrate W while crossing the substrate W on the polishing surface 2a each time the polishing table 3 makes one rotation. The sensor 30 is electrically connected to the operation controller 50, and the film thickness monitoring signals output by the sensor 30 are sent to the operation controller 50.

[0037] 3 is a schematic diagram showing an example of a plurality of measurement points MP1 to MP4 on the surface (surface to be polished) of the substrate W. As shown in FIG. 3, the sensor 30 outputs film thickness monitoring signals at the plurality of measurement points MP1 to MP4 each time it traverses the substrate W. The plurality of (four in this embodiment) regions C1 to C4 on the substrate W correspond to the pressure chambers 40A to 40D of the polishing head 10 described above, respectively. That is, region C1 is the center of the substrate W, region C2 is the inner middle portion of the substrate W, region C3 is the outer middle portion of the substrate W, and region C4 is the edge portion of the substrate W.

[0038] The measurement points MP1 are located in region C1, the measurement points MP2 are located in region C2, the measurement points MP3 are located in region C3, and the measurement points MP4 are located in region C4. The positions of the measurement points MP1 to MP4 are determined based on the time interval at which the sensor 30 outputs a film thickness monitoring signal, the rotation speed of the polishing table 3, the position of the polishing head 10, and the rotation speed of the polishing head 10, etc. FIG. 3 shows an example of an arrangement in which the sensor 30 crosses the center CP of the substrate W. That is, one of the measurement points MP1 located in region C1 is located at the center CP of the substrate W. However, the arrangement of the sensor 30 is not limited to this example, as long as the sensor 30 can cross below the substrate W.

[0039] The operation control unit 50 associates each of the film thickness monitoring signals at the measurement points MP1 to MP4 with measurement coordinates that indicate the position of the measurement point. The measurement coordinates are coordinates (position coordinates) that indicate a position on the surface of the substrate W. For example, the measurement coordinates are indicated as a position in the radial direction on the substrate W. Each time the sensor 30 passes over the substrate W, the operation control unit 50 associates the film thickness monitoring signal at each measurement point with the measurement coordinates.

[0040] The measurement coordinates are determined, for example, as follows: The operation control unit 50 is electrically connected to the table motor 6. The operation control unit 50 receives information regarding the rotation of the polishing table 3 from the table motor 6. The operation control unit 50 determines that the sensor 30 is moving below the substrate W when the polishing table 3 is within a predetermined rotation angle range. Based on this determination, the operation control unit 50 causes the sensor 30 to output a film thickness monitoring signal at a predetermined measurement interval. Furthermore, based on this determination, the operation control unit 50 detects the rotation speed (or angular velocity) of the polishing table 3 while the film thickness monitoring signal is being output. Based on the detected rotation speed, the operation control unit 50 determines the rotation angle at a predetermined time. As a result, the operation control unit 50 determines the position of the sensor 30 at the predetermined time based on the rotation angle. Furthermore, based on the determined position of the sensor 30 and the measurement interval, the operation control unit 50 determines the position of the measurement point, i.e., the measurement coordinates. In this way, the operation control unit 50 associates the film thickness monitoring signal at a predetermined measurement point with the measurement coordinates.

[0041] The range of the predetermined rotation angle for determining that the sensor 30 is passing below the substrate W can be set in advance based on the position and size of the substrate W. The measurement coordinates may be determined by a method other than the above.

[0042] The operation control unit 50 determines regions C1 to C4 on the substrate W in which the measurement points MP1 to MP4 are located, based on the measurement coordinates of each of the measurement points MP1 to MP4. For example, the operation control unit 50 determines, based on the measurement coordinates of each of the measurement points MP1, that the region in which the measurement points MP1 are located is C1. In one embodiment, the operation control unit 50 may calculate a signal average value, which is the average value of the output values ​​of the film thickness monitoring signals at the measurement points MP1 located in region C1. In this case, the signal average value is similarly calculated for the measurement points MP2 located in region C2, the measurement points MP3 located in region C3, and the measurement points MP4 located in region C4.

[0043] FIG. 4 is a cross-sectional view showing an example of a layered structure of a substrate W to be polished. The substrate shown in FIG. 4 has a silicon nitride (Si3N4) stopper layer 101 formed on the convex portions of a silicon (Si) layer 100 having uneven steps, and a layered film 102 to be polished having uneven steps is formed on the stopper layer 101. In this embodiment, the layered film 102 to be polished is an insulating film made of silicon dioxide (SiO2). An example of the layered structure shown in FIG. 4 is shallow trench isolation (STI). In this embodiment, the polishing endpoint of the substrate W is the point at which the film thickness of the substrate W reaches a target film thickness. The substrate W is polished until the stopper layer 101 appears on the surface of the substrate W as the polishing of the layered film 102 progresses. However, the layered structure of the substrate W is not limited to this example, and the substrate W is polished until the film thickness reaches a predetermined target film thickness.

[0044] Fig. 5 is a graph showing an example of the relationship between the output value of the film thickness monitoring signal and the polishing time in multiple regions C1 to C4 of the substrate W. In Fig. 5, the solid line represents the relationship between the output value of the film thickness monitoring signal and the polishing time in region C1 on the substrate W, the dashed line represents the relationship between the output value of the film thickness monitoring signal and the polishing time in region C2 on the substrate W, the thick line represents the relationship between the output value of the film thickness monitoring signal and the polishing time in region C3 on the substrate W, and the dashed line represents the relationship between the output value of the film thickness monitoring signal and the polishing time in region C4 on the substrate W.

[0045] In the example shown in FIG. 5, the initial film thicknesses of regions C1 to C4 (i.e., the film thicknesses of the substrate W before polishing) are different. The initial film thicknesses of regions C1 to C4, in descending order, are the initial film thickness of region C4, the initial film thickness of region C3, the initial film thickness of region C2, and the initial film thickness of region C1. However, the relationship in the magnitude of the initial film thicknesses of regions C1 to C4 shown in FIG. 5 is merely an example, and is not particularly limited to this example. The output values ​​of the film thickness monitoring signal indicating the initial film thicknesses of regions C1, C2, C3, and C4 are Sini1, Sini2, Sini3, and Sini4, respectively. The magnitude relationship of these film thickness monitoring signal output values ​​Sini1 to Sini4 is Sini4>Sini3>Sini2>Sini1.

[0046] In the example shown in Figure 5, the polishing rate in each of the multiple regions C1 to C4 on the substrate W is constant during polishing of the substrate W. Therefore, the output value of the film thickness monitoring signal in each of the multiple regions C1 to C4 decreases linearly with polishing time. The polishing endpoints Tfin1 to Tfin4 in the multiple regions C1 to C4 are the times when the output value of the film thickness monitoring signal in each of the multiple regions C1 to C4 reaches the target signal value Sfin, which indicates the target film thickness. As shown in Figure 5, these polishing endpoints Tfin1, Tfin2, Tfin3, and Tfin4 may occur at different times. Therefore, if polishing of the substrate W is terminated based on the polishing endpoint of one of the multiple regions C1 to C4, over-polishing or under-polishing may occur in the other regions.

[0047] In another example, the substrate W may be polished while adjusting the polishing rates in the multiple regions C1 to C4 of the substrate W (while adjusting the pressures in the pressure chambers 40A to 40D corresponding to the regions C1 to C4) based on the film thickness monitoring signal acquired during polishing of the substrate W. However, due to differences in the surface structures and underlying structures of the multiple regions C1 to C4, it may be difficult to adjust the polishing rates in the multiple regions C1 to C4 of the substrate W so that the polishing endpoints Tfin1, Tfin2, Tfin3, and Tfin4 arrive at the same time.

[0048] In this embodiment, the operation control unit 50 is configured to determine polishing endpoints Tfin1 to Tfin4 in regions C1 to C4, respectively, based on the film thickness monitoring signals in regions C1 to C4 on the substrate W. Specifically, the operation control unit 50 determines a polishing endpoint Tfin1, which is the point at which the output value of the film thickness monitoring signal in region C1 on the substrate W reaches a target signal value Sfin indicating the target film thickness, determines a polishing endpoint Tfin2, which is the point at which the output value of the film thickness monitoring signal in region C2 on the substrate W reaches the target signal value Sfin, determines a polishing endpoint Tfin3, which is the point at which the output value of the film thickness monitoring signal in region C3 on the substrate W reaches the target signal value Sfin indicating the target film thickness, and determines a polishing endpoint Tfin4, which is the point at which the output value of the film thickness monitoring signal in region C4 on the substrate W reaches the target signal value Sfin indicating the target film thickness.

[0049] 3, the operation control unit 50 may be configured to calculate a plurality of signal average values ​​in regions C1 to C4 on the substrate W, and determine polishing endpoints Tfin1 to Tfin4 in regions C1 to C4, respectively, based on the plurality of signal average values ​​corresponding to regions C1 to C4. Specifically, the operation control unit 50 may calculate a signal average value in region C1 on the substrate W, and determine polishing endpoint Tfin1, which is the point at which the signal average value in region C1 reaches a target signal value Sfin. The same applies to determining polishing endpoints Tfin2 to Tfin4 in regions C2 to C4 on the substrate W.

[0050] When the polishing endpoint Tfin1 in region C1, which is the initial polishing endpoint, is reached, the operation control unit 50 issues a command to the pressure regulator Ra1, which adjusts the pressure in the pressure chamber 40A corresponding to region C1, to reduce the pressure in the pressure chamber 40A and thereby stop the polishing in region C1. Even after the polishing in region C1 is stopped, the polishing in regions C2 to C4 continues. The pressure value when reducing the pressure in the pressure chamber 40A may be 0, or may be a pressure value that generates a slight positive pressure in the pressure chamber 40A. In this specification, "stopping the polishing" includes not only completely stopping the polishing but also slightly progressing the polishing to an extent that does not affect the polishing quality.

[0051] When the polishing end point Tfin2 in region C2, which is the second polishing end point after polishing end point Tfin1, is reached, the operation control unit 50 issues a command to the pressure regulator Ra2 that adjusts the pressure in the pressure chamber 40B corresponding to region C2 to reduce the pressure in the pressure chamber 40B, thereby stopping the polishing of region C2. Even after the polishing of region C2 is stopped, the polishing of regions C3 and C4 continues.

[0052] When the polishing end point Tfin3 in region C3, which is the (third) polishing end point after polishing end point Tfin2, is reached, the operation control unit 50 issues a command to the pressure regulator Ra3 that adjusts the pressure in the pressure chamber 40C corresponding to region C3 to reduce the pressure in the pressure chamber 40C, thereby stopping the polishing of region C3. Even after the polishing of region C3 has been stopped, the polishing of region C4 continues.

[0053] When the polishing end point Tfin4 in region C4, which is the final polishing end point and is later than polishing end point Tfin3, is reached, the operation control unit 50 issues a command to the pressure regulator Ra4 that adjusts the pressure in the pressure chamber 40D corresponding to region C4 to reduce the pressure in the pressure chamber 40D and thereby stop the polishing of region C4. In this manner, polishing of all regions C1 to C4 on the substrate W is stopped. However, the order in which the polishing end points Tfin1 to Tfin4 are reached as shown in FIG. 5 is merely an example, and the order is not particularly limited to this example.

[0054] In one embodiment, when the first polishing endpoint Tfin1 is reached, the operation control unit 50 may issue a command to the atmosphere release valve Vc1, which opens the pressure chamber 40A corresponding to the region C1 to the atmosphere, instead of the pressure regulator Ra1, to stop the progress of polishing in the region C1 by opening the pressure chamber 40A to the atmosphere. Similarly, when the polishing endpoints Tfin2 to Tfin4 are reached, the operation control unit 50 may issue a command to the atmosphere release valves Vc2 to Vc4 to open the pressure chambers 40B to 40D to the atmosphere, to stop the progress of polishing in the regions C2 to C4, respectively.

[0055] In one embodiment, the operation control unit 50 may issue a command to the pressure regulator Ra1 to reduce the pressure in the pressure chamber 40A after a predetermined time (e.g., several seconds) has elapsed since the first polishing endpoint Tfin1 was reached, thereby stopping the progress of polishing in the region C1. Similarly, after a predetermined time (e.g., several seconds) has elapsed since the polishing endpoints Tfin2 to Tfin4 were reached, the operation control unit 50 may issue a command to the pressure regulators Ra2 to Ra4 to reduce the pressure in the pressure chambers 40B to 40D, thereby stopping the progress of polishing in the regions C2 to C4, respectively.

[0056] After polishing of all of the regions C1 to C4 on the substrate W has stopped, a polishing completion operation for the substrate W is performed. In the polishing completion operation for the substrate W, the operation control unit 50 issues a command to the polishing liquid supply nozzle 20 to stop supplying the polishing liquid to the polishing surface 2a of the polishing pad 2, and issues a command to the pure water supply nozzle (not shown) to supply pure water to the polishing surface 2a to wash away the polishing liquid present on the polishing surface 2a. Furthermore, the operation control unit 50 issues a command to the polishing head lifting mechanism to lift the polishing head 10 and move the substrate W away from the polishing surface 2a.

[0057] In one embodiment, the polishing end operation for the substrate W may be performed after a predetermined time (e.g., several seconds) has elapsed after the final polishing end point Tfin4 is reached and the polishing progress of the region C4 is stopped by lowering the pressure in the pressure chamber 40D.

[0058] According to this embodiment, polishing endpoints Tfin1 to Tfin4 are determined for multiple regions C1 to C4 on the substrate W, and when the polishing endpoint of each region is reached, the pressure in the corresponding pressure chamber is reduced to stop the polishing of each region. Therefore, polishing can be stopped at an appropriate polishing endpoint for each region on the substrate W, preventing under-polishing and over-polishing of the substrate W.

[0059] 6 is a graph showing an example of the relationship between the output value of the film thickness monitoring signal and the polishing time in multiple regions C1 to C4 of a substrate W according to another embodiment. In this embodiment, the operation control unit 50 is configured to stop the progress of polishing of region C1 by reducing the pressure in the pressure chamber 40A corresponding to region C1 on the substrate W when the first polishing endpoint Tfin1 is reached, and to increase the polishing rate in regions C2 to C4 by increasing the pressure in the pressure chambers 40B to 40D corresponding to regions C2 to C4 on the substrate W.

[0060] Specifically, when the polishing endpoint Tfin1 in region C1 on the substrate W, which is the initial polishing endpoint, is reached, the operation control unit 50 calculates a correction pressure value in the pressure chamber 40B for increasing the polishing rate in region C2 based on the output value S2 of the film thickness monitoring signal corresponding to the film thickness in region C2 at polishing endpoint Tfin1 and the target signal value Sfin indicating the target film thickness. This correction pressure value is higher than the current pressure in the pressure chamber 40B (the currently set target pressure value). The correction pressure value is calculated so that the greater the difference between the output value S2 of the film thickness monitoring signal and the target signal value Sfin, the greater the increase rate of the correction pressure value relative to the current pressure in the pressure chamber 40B (the currently set target pressure value).

[0061] In one embodiment, the operation control unit 50 may calculate the current polishing rate in region C2 from the difference between the output value S2 of the film thickness monitoring signal and the output value Sini2 of the film thickness monitoring signal indicating the initial film thickness in region C2, and the polishing time at the polishing endpoint Tfin1. In this case, the operation control unit 50 calculates a correction pressure value in the pressure chamber 40B so as to obtain a polishing rate higher than the current polishing rate in region C2. The operation control unit 50 calculates the correction pressure value in the pressure chamber 40B so as to obtain a polishing rate with a larger percentage increase from the current polishing rate as the difference between the output value S2 of the film thickness monitoring signal and the target signal value Sfin increases.

[0062] The operation control unit 50 is configured to issue a command to the pressure regulator Ra2, which adjusts the pressure in the pressure chamber 40B corresponding to the region C2, to increase the pressure in the pressure chamber 40B to the calculated corrected pressure value, thereby increasing the polishing rate in the region C2. The operation control unit 50 then determines a polishing endpoint Tfin2', which is the point at which the output value of the film thickness monitoring signal in the region C2 on the substrate W reaches the target signal value Sfin. When the polishing endpoint Tfin2' is reached, the operation control unit 50 issues a command to the pressure regulator Ra2 to reduce the pressure in the pressure chamber 40B, thereby stopping the progress of polishing in the region C2.

[0063] In this embodiment, the operation control unit 50 calculates a corrected pressure value for the pressure chamber 40C corresponding to the region C3 based on the output value S3 of the film thickness monitoring signal corresponding to the film thickness in the region C3 at the polishing endpoint Tfin1 and the target signal value Sfin indicating the target film thickness. Similarly, the operation control unit 50 calculates a corrected pressure value for the pressure chamber 40D corresponding to the region C4 based on the output value S4 of the film thickness monitoring signal corresponding to the film thickness in the region C4 at the polishing endpoint Tfin1 and the target signal value Sfin indicating the target film thickness. The operation control unit 50 issues commands to the pressure regulators Ra3 and Ra4, which adjust the pressure in the pressure chambers 40C and 40D, respectively, to increase the pressures in the pressure chambers 40C and 40D to the calculated corrected pressure values, thereby increasing the polishing rates in the regions C3 and C4. The operation control unit 50 then determines polishing endpoints Tfin3' and Tfin4', which are the points at which the output values ​​of the film thickness monitoring signal in regions C3 and C4 on the substrate W reach the target signal value Sfin, respectively. When the polishing endpoint Tfin3' is reached, the operation control unit 50 issues a command to the pressure regulator Ra3 to reduce the pressure in the pressure chamber 40C, thereby stopping the polishing of region C3. When the polishing endpoint Tfin4' is reached, the operation control unit 50 issues a command to the pressure regulator Ra4 to reduce the pressure in the pressure chamber 40D, thereby stopping the polishing of region C4.

[0064] In this embodiment, the polishing endpoints Tfin2', Tfin3', and Tfin4' are the same, but in another embodiment, the polishing endpoints Tfin2', Tfin3', and Tfin4' may be different. In this case, when the second polishing endpoint (e.g., polishing endpoint Tfin2') is reached, the operation controller 50 may stop the progress of polishing in the region (e.g., region C2) by reducing the pressure in the pressure chamber (e.g., pressure chamber 40B) corresponding to the region (e.g., region C2) that has reached the second polishing endpoint, and may further increase the pressure in the pressure chambers (e.g., pressure chambers 40C and 40D) corresponding to the other regions (e.g., regions C3 and C4) to further increase the polishing rates in the other regions (e.g., regions C3 and C4).

[0065] In one embodiment, when the first polishing endpoint Tfin1 is reached, the operation control unit 50 may increase the pressure in a pressure chamber corresponding to at least one of the regions C2 to C4 on the substrate W. For example, when the first polishing endpoint Tfin1 is reached, the operation control unit 50 may increase only the pressure in a pressure chamber (pressure chamber 40D in the example of FIG. 6) corresponding to the region where the difference between the output value of the film thickness monitoring signal at the polishing endpoint Tfin1 and the target signal value Sfin is largest (region C4 in the example of FIG. 6), thereby increasing only the polishing rate in that region.

[0066] According to this embodiment, the overall polishing time for the substrate W can be shortened. Furthermore, in the region where polishing was stopped first (region C1 in the example of FIG. 6 ), even after the pressure in the corresponding pressure chamber (pressure chamber 40A in the example of FIG. 6 ) is reduced, the contact portion 45 (see FIG. 2 ) of the elastic film 44 may come into contact with the region where polishing was stopped first (region C1 in the example of FIG. 6 ) while other regions (regions C2 to C4 in the example of FIG. 6 ) are being polished. If this state continues for a long time, the region where polishing was stopped will be unintentionally polished. Therefore, by minimizing the time difference between the end point of the earlier polishing and the polishing end point that follows the earlier polishing end point, over-polishing in the region where polishing was stopped first can be prevented.

[0067] 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]

[0068] 1 Polishing equipment 2 polishing pads 2a Polished surface 3 Polishing table 5 Table shaft 6 Table Motor 10 Polishing Head 12 Grinding head shaft 15 Rotary joint 20 Polishing liquid supply nozzle 30 sensors 40A, 40B, 40C, 40D, 40E Pressure chamber 41 Career 42 Retainer ring 44 Elastic membrane 45 Contact area 45a Contact surface 46a,46b,46c Inner wall 46d Exterior wall 47 Membrane (rolling diaphragm) 50 Operation control section 50a storage device 50b Arithmetic unit F1, F2, F3, F4, F5 gas transfer lines La1, La2, La3, La4, La5 gas supply line Va1, Va2, Va3, Va4, Va5 gas supply valves Ra1,Ra2,Ra3,Ra4,Ra5 Pressure Regulators Lb1, Lb2, Lb3, Lb4, Lb5 vacuum lines Vb1, Vb2, Vb3, Vb4, Vb5 vacuum valves Rb1, Rb2, Rb3, Rb4, Rb5 vacuum regulators Lc1, Lc2, Lc3, Lc4, Lc5 Atmospheric release line Vc1, Vc2, Vc3, Vc4, Vc5 Atmospheric release valve MP1, MP2, MP3, MP4 measurement points

Claims

1. a polishing table supporting a polishing pad is rotated, and the substrate is pressed against the polishing surface of the polishing pad by the first pressure chamber and the second pressure chamber of the polishing head, thereby polishing the substrate; outputting a film thickness monitoring signal corresponding to a film thickness of the substrate by a sensor while the substrate is being polished; determining a first polishing end point in a first region and a second polishing end point in a second region on the substrate corresponding to the first pressure chamber and the second pressure chamber, respectively, based on the film thickness monitoring signals in the first region and the second region on the substrate corresponding to the first pressure chamber and the second pressure chamber, the second polishing end point being a polishing end point later than the first polishing end point; When the first polishing end point is reached, the pressure in the first pressure chamber is reduced to stop the polishing of the first region; When the second polishing endpoint is reached, the pressure in the second pressure chamber is reduced to stop the polishing of the second region.

2. 2. The polishing method according to claim 1, wherein determining the first polishing end point and the second polishing end point based on the film thickness monitoring signal in the first region and the second region, respectively, comprises determining the first polishing end point as a time point at which the output value of the film thickness monitoring signal in the first region reaches a target signal value indicating a target film thickness, and determining the second polishing end point as a time point at which the output value of the film thickness monitoring signal in the second region reaches the target signal value.

3. 2. The polishing method according to claim 1, wherein stopping the progress of polishing of the first region by reducing the pressure in the first pressure chamber when the first polishing endpoint is reached comprises stopping the progress of polishing of the first region by opening the first pressure chamber to the atmosphere when the first polishing endpoint is reached.

4. 2. The polishing method according to claim 1, further comprising increasing the pressure in the second pressure chamber when the first polishing endpoint is reached, thereby increasing the polishing rate in the second region.

5. 5. The polishing method according to claim 4, wherein increasing the polishing rate in the second region by increasing the pressure in the second pressure chamber when the first polishing endpoint is reached comprises calculating a corrected pressure value in the second pressure chamber based on an output value of a film thickness monitoring signal corresponding to the film thickness in the second region at the first polishing endpoint and a target signal value indicating a target film thickness when the first polishing endpoint is reached, and increasing the pressure in the second pressure chamber to the corrected pressure value, thereby increasing the polishing rate in the second region.

6. determining the first polishing end point and the second polishing end point based on the film thickness monitoring signals in the first region and the second region, respectively; calculating a signal average value, which is an average value of output values ​​of a plurality of film thickness monitoring signals from a plurality of measurement points located in each of the first region and the second region; 2. The polishing method according to claim 1, wherein the first polishing endpoint and the second polishing endpoint are determined based on the average signal values ​​in the first region and the second region, respectively.

7. a polishing table supporting a polishing pad; a table motor for rotating the polishing table; a polishing head having a first pressure chamber and a second pressure chamber for pressing the substrate against the polishing surface of the polishing pad; a first pressure regulator that adjusts the pressure in the first pressure chamber; a second pressure regulator that adjusts the pressure in the second pressure chamber; a sensor that outputs a film thickness monitoring signal corresponding to the film thickness of the substrate; an operation control unit that controls operations of the first pressure regulator and the second pressure regulator; The operation control unit determining a first polishing end point in a first region and a second polishing end point in a second region on the substrate corresponding to the first pressure chamber and the second pressure chamber, respectively, based on the film thickness monitoring signals in the first region and the second region on the substrate corresponding to the first pressure chamber and the second pressure chamber, the second polishing end point being a polishing end point later than the first polishing end point; When the first polishing endpoint is reached, a command is issued to the first pressure regulator to reduce the pressure in the first pressure chamber, thereby stopping the progress of polishing of the first region; a polishing apparatus configured to stop the progress of polishing of the second region by issuing a command to the second pressure regulator to reduce the pressure in the second pressure chamber when the second polishing endpoint is reached.

8. 8. The polishing apparatus according to claim 7, wherein the operation control unit is configured to determine the first polishing endpoint as a point in time when the output value of the film thickness monitoring signal in the first region reaches a target signal value indicating a target film thickness, and to determine the second polishing endpoint as a point in time when the output value of the film thickness monitoring signal in the second region reaches the target signal value.

9. a first atmosphere release valve that opens the first pressure chamber to the atmosphere; 8. The polishing apparatus according to claim 7, wherein the operation control unit is configured to issue a command to the first atmosphere release valve instead of the first pressure regulator when the first polishing endpoint is reached, thereby opening the first pressure chamber to the atmosphere and thereby stopping the progress of polishing of the first region.

10. 8. The polishing apparatus according to claim 7, wherein the operation control unit is configured to issue a command to the first pressure regulator to reduce the pressure in a first pressure chamber of the polishing head corresponding to the first region, thereby stopping the progress of polishing of the first region, when the first polishing end point is reached, and to issue a command to the second pressure regulator to increase the pressure in the second pressure chamber, thereby increasing the polishing rate in the second region.

11. 11. The polishing apparatus according to claim 10, wherein the operation control unit is configured to, when the first polishing endpoint is reached, calculate a compensation pressure value in the second pressure chamber based on an output value of a film thickness monitoring signal corresponding to the film thickness in the second region at the first polishing endpoint and a target signal value indicating a target film thickness, and issue a command to the second pressure regulator to increase the pressure in the second pressure chamber to the compensation pressure value, thereby increasing the polishing rate in the second region.

12. The operation control unit calculating a signal average value, which is an average value of output values ​​of a plurality of film thickness monitoring signals from a plurality of measurement points located in each of the first region and the second region; 8. The polishing apparatus according to claim 7, wherein the first polishing endpoint and the second polishing endpoint are determined based on the average signal values ​​in the first region and the second region, respectively.

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