Polishing apparatus, polishing method, and method for outputting visualization information of film thickness distribution of substrate

Abstract

To provide a polishing device capable of acquiring accurate film thickness distribution information.SOLUTION: A polishing device comprises: a polishing table for supporting a polishing pad 2; a plurality of film thickness sensors 60A-60G that are embedded in the polishing table and that output a plurality of signals depending on the film thickness of a base plate; and a control unit 9. The control unit 9 outputs visualized information on film thickness distribution in which a notch position is set to be a reference position, by analyzing film thickness distribution information of the base plate while identifying the notch position of the base plate on the basis of measured film thickness information.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a polishing apparatus, a polishing method, and a method for outputting visualization information of a film thickness distribution of a substrate.

Background Art

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

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

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

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, the required degree of film thickness uniformity has been increasing. Therefore, it has become necessary to manage and control the polishing process while taking more into account the variation in the circumferential direction of the initial film thickness of the wafer due to the characteristics of the film forming apparatus and the like, and the variation in the circumferential polishing amount caused by polishing (for example, it is effective to actively polish the thick film portions of the wafer or the portions other than the thin film portions of the wafer to improve the uniformity of the film thickness distribution of the wafer).

[0007] Therefore, an object of the present invention is to provide a polishing apparatus and a polishing method capable of acquiring accurate film thickness distribution information. An object of the present invention is to provide a method for outputting visualization information of an accurate film thickness distribution.

Means for Solving the Problems

[0008] In one aspect, there is provided a polishing apparatus including a polishing table that supports a polishing pad, a plurality of film thickness sensors embedded in the polishing table that output a plurality of signals corresponding to the film thickness of a substrate, and a control device that measures the film thickness information of the substrate based on the plurality of signals acquired from the plurality of film thickness sensors. On the polishing pad, when an inner region where the peripheral edge of the substrate contacts is defined as an inner edge portion and an outer region where the peripheral edge of the substrate contacts is defined as an outer edge portion, the plurality of film thickness sensors are arranged from the inner edge portion to the outer edge portion, and the control device, based on the measured film thickness information, specifies the notch position of the substrate, analyzes the film thickness distribution information of the substrate, and outputs visualization information of the film thickness distribution with the notch position as a reference position.

[0009] In one aspect, each of the plurality of film thickness sensors includes a PSD sensor. In one aspect, the control device includes a median filter unit that performs median filtering on a plurality of signals acquired from each of the plurality of film thickness sensors. The median filter unit performs median filtering on the plurality of signals acquired from each of the plurality of film thickness sensors to remove noise from the plurality of signals. In one aspect, the polishing apparatus includes a wear amount detection device that outputs a signal corresponding to the wear amount of the polishing pad. The control device measures the wear amount of the polishing pad based on the signal acquired from the wear amount detection device, and corrects the film thickness information based on the measured wear amount of the polishing pad.

[0010] In one aspect, the polishing apparatus includes a display device connected to the control device. The control device outputs visualization information of the film thickness distribution to the display device.

[0011] Provided is a polishing apparatus including a polishing table that supports a polishing pad, a polishing head having a plurality of pressing elements for pressing a substrate against a polishing surface of the polishing pad, a pressing force control unit capable of individually controlling the pressing forces of the plurality of pressing elements, a plurality of film thickness sensors embedded in the polishing table and outputting a plurality of signals corresponding to the film thickness of the substrate, and a control device that measures film thickness information of the substrate based on the signals acquired from the plurality of film thickness sensors. The plurality of pressing elements are arranged at least along the circumferential direction of the polishing head. When an inner region where the peripheral edge of the substrate contacts on the polishing pad is defined as an inner edge portion and an outer region where the peripheral edge of the substrate contacts is defined as an outer edge portion, the plurality of film thickness sensors are arranged from the inner edge portion to the outer edge portion. The control device controls a specific pressing element via the pressing force control unit based on the measured film thickness information to control the pressing force at a specific position on the substrate.

[0012] In one aspect, the polishing apparatus includes a rotation angle detector that detects the rotation angle of the polishing head, and the control device controls a specific pressing element via the pressing force control unit based on the rotation angle of the polishing head acquired from the rotation angle detector and the measured film thickness information, thereby controlling the pressing force at a specific position on the substrate. In one aspect, the control device identifies the notch position of the substrate based on the measured film thickness information, determines a specific position on the substrate from the relationship between the rotation angle of the polishing head and the notch position, and controls a specific pressing element via the pressing force control unit, thereby controlling the pressing force at a specific position on the substrate. In one aspect, the control device identifies a specific position on the substrate based on the measured film thickness information, and based on the relationship between the rotation angle of the polishing head and the specific position on the substrate, controls a specific pressing element via the pressing force control unit, thereby controlling the pressing force at a specific position on the substrate.

[0013] In one aspect, a method for outputting visualization information of the film thickness distribution of a substrate is provided. This method defines the inner region where the peripheral portion of the substrate contacts as the inner edge portion and the outer region where the peripheral portion of the substrate contacts as the outer edge portion on the polishing pad, and acquires a plurality of signals corresponding to the film thickness of the substrate from a plurality of film thickness sensors arranged from the inner edge portion to the outer edge portion. Based on the acquired plurality of signals, the film thickness information of the substrate is measured. Based on the measured film thickness information, while identifying the notch position of the substrate, the film thickness distribution information of the substrate is analyzed, and visualization information of the film thickness distribution with the notch position as the reference position is output.

[0014] In one aspect, a plurality of signals corresponding to the film thickness of the substrate are acquired from a plurality of PSD sensors. In one aspect, the acquired plurality of signals are subjected to median filter processing to remove noise from the plurality of signals. In one aspect, a signal corresponding to the wear amount of the polishing pad is acquired from a wear amount detection device, the wear amount of the polishing pad is measured based on the acquired signal, and the film thickness distribution information of the substrate is corrected based on the measured wear amount of the polishing pad.

[0015] In one aspect, the visualization information of the film thickness distribution is output to a display device.

[0016] In one aspect, when, on the polishing pad, an inner region where the peripheral edge of the substrate contacts is defined as an inner edge portion and an outer region where the peripheral edge of the substrate contacts is defined as an outer edge portion, a plurality of signals corresponding to the film thickness of the substrate are acquired from a plurality of film thickness sensors arranged from the inner edge portion to the outer edge portion, the film thickness information of the substrate is measured based on the acquired plurality of signals, and at least a plurality of pressing elements arranged along the circumferential direction of the polishing head for pressing the substrate against the polishing surface of the polishing pad are controlled based on the measured film thickness information, thereby controlling the pressing force at a specific position on the substrate, and a polishing method is provided.

[0017] In one aspect, the rotation angle of the polishing head is acquired by a rotation angle detector that detects the rotation angle of the polishing head, and the plurality of pressing elements are controlled based on the rotation angle of the polishing head acquired from the rotation angle detector and the measured film thickness information, thereby controlling the pressing force at a specific position on the substrate. In one aspect, based on the measured film thickness information, the notch position of the substrate is specified, a specific position on the substrate is determined from the relationship between the rotation angle of the polishing head and the notch position, and the plurality of pressing elements are controlled, thereby controlling the pressing force at a specific position on the substrate. In one aspect, based on the measured film thickness information, a specific position on the substrate is specified, and the plurality of pressing elements are controlled based on the relationship between the rotation angle of the polishing head and the specific position on the substrate, thereby controlling the pressing force at a specific position on the substrate.

Advantages of the Invention

[0018] According to the present invention, by providing a plurality of film thickness sensors, the control device can acquire accurate film thickness distribution information including the notch position of the wafer.

Brief Description of the Drawings

[0019]

Figure 1

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Figure 9

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Figure 11

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals, and redundant descriptions are omitted.

[0021] FIG. 1 is a schematic diagram showing an embodiment of a polishing apparatus. As shown in FIG. 1, the polishing apparatus includes a polishing head (substrate holding device) 1 that holds and rotates a wafer W, which is an example of a substrate, a polishing table 3 that supports a polishing pad 2, a polishing liquid supply nozzle 5 that supplies a polishing liquid (slurry) to the polishing pad 2, and a control device 9 that controls the operations of these components of the polishing apparatus.

[0022] The polishing head 1 and the polishing table 3 rotate in the same direction. In this state, the polishing head 1 presses the wafer W against the polishing surface 2a of the polishing pad 2. A polishing liquid is supplied onto the polishing pad 2 from the polishing liquid supply nozzle 5, and the wafer W is polished by sliding contact with the polishing pad 2 in the presence of the polishing liquid.

[0023] The polishing table 3 is connected to a table motor 13 disposed below it via a table shaft 3a and is rotatable around the table shaft 3a. A polishing pad 2 is attached to the upper surface of the polishing table 3, and the upper surface of the polishing pad 2 constitutes a polishing surface 2a for polishing the wafer W. By rotating the polishing table 3 with the table motor 13, the polishing surface 2a moves relative to the polishing head 1. Therefore, the table motor 13 constitutes a polishing surface moving mechanism that moves the polishing surface 2a in the horizontal direction.

[0024] The polishing head 1 is connected to a polishing head shaft 11, and this polishing head shaft 11 is configured to move up and down relative to the head arm 16 by a vertical movement mechanism 27. By the up and down movement of the polishing head shaft 11, the entire polishing head 1 is raised and lowered relative to the head arm 16 for positioning.

[0025] The control device 9 is composed of at least one computer. The control device 9 includes a storage device 9a in which a program is stored and a processing device 9b that executes calculations according to instructions included in the program. The processing device 9b includes a CPU (central processing unit) or a GPU (graphics processing unit) that performs calculations according to instructions included in the program stored in the storage device 9a.

[0026] The head arm 16 is provided with a polishing head height sensor 39 facing the bridge 28. This polishing head height sensor 39 is electrically connected to the control device 9. The polishing head height sensor 39 detects a physical quantity corresponding to the height of the polishing head 1 from the position of the bridge 28 that moves up and down integrally with the polishing head 1, and outputs a signal corresponding to this height. The control device 9 measures the height of the polishing head 1 based on the signal sent from the polishing head height sensor 39.

[0027] The polishing head 1 is adapted to hold the wafer W on its lower surface. The polishing head 1 holding the wafer W on its lower surface is moved from the wafer transfer position to a position above the polishing table 3 by the rotation of the head arm 16. The polishing head 1 and the polishing table 3 are rotated respectively, and polishing liquid is supplied onto the polishing pad 2 from a polishing liquid supply nozzle 5 provided above the polishing table 3. Then, the wafer W is pressed against the polishing surface 2a of the polishing pad 2 by the polishing head 1, and the wafer W is brought into sliding contact with the polishing surface 2a of the polishing pad 2 in the presence of the polishing liquid. The surface of the wafer W is polished by the chemical action of the chemical components of the polishing liquid and the mechanical action of the abrasive grains contained in the polishing liquid.

[0028] As shown in FIG. 1, the polishing apparatus includes a dressing unit 50 for dressing the polishing surface 2a of the polishing pad 2. The dressing unit 50 includes a dresser 51 that is brought into sliding contact with the polishing surface 2a, a dresser shaft 52 to which the dresser 51 is connected, and a swing arm 55 that rotatably supports the dresser shaft 52.

[0029] The dressing unit 50 is provided with a displacement sensor 56 for detecting the displacement of the dresser 51. The displacement sensor 56 is provided on the upper surface of the swing arm 55. A target plate 57 is fixed to the dresser shaft 52. Therefore, the target plate 57 moves up and down as the dresser 51 moves up and down. The displacement sensor 56 is disposed to penetrate the target plate 57 and detects the displacement of the target plate 57 (i.e., the dresser 51). Note that as the displacement sensor 56, any type of sensor such as a linear scale, a laser sensor, an ultrasonic sensor, or an eddy current sensor can be used.

[0030] The displacement sensor 56 is a wear amount detection device that outputs a signal corresponding to the wear amount of the polishing pad 2. The control device 9 is electrically connected to the displacement sensor 56 and is configured to measure the wear amount of the polishing pad 2 based on the signal acquired from the displacement sensor 56.

[0031] The wear amount of the polishing pad 2 is measured as follows. First, the dresser 51 is lowered to bring the dresser 51 into contact with the polishing surface 2a of the initial polishing pad 2. In this state, the displacement sensor 56 detects the initial position of the dresser 51, and the control device 9 stores the initial position detected by the dresser 51 in the storage device 9a of the control device 9. Then, after the polishing of the wafer W is completed, the dresser 51 is again brought into contact with the polishing surface 2a of the polishing pad 2. In this state, the displacement sensor 56 detects the current position of the dresser 51. Since the lowering position of the dresser 51 is displaced downward according to the wear amount of the polishing pad 2, the control device 9 can measure the wear amount of the polishing pad 2 by calculating the difference between the initial position of the dresser 51 and the current position of the dresser 51 after polishing.

[0032] Next, the polishing head 1 will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view of the polishing head. As shown in FIG. 2, the polishing head 1 includes a head body 102 that presses the wafer W against the polishing surface 2a, and a retainer ring 103 disposed so as to surround the wafer W. The retainer ring 103 is configured to be vertically movable independently of the head body 102.

[0033] The polishing head 1 has a plurality of pressing elements for pressing the wafer W against the polishing surface 2a of the polishing pad 2. Examples of the pressing elements include a pressurizing mechanism provided on the polishing head 1 or a piezoelectric element provided on the polishing head 1. In the present embodiment, the pressing element is a pressurizing mechanism provided on the polishing head 1. Hereinafter, the details of the pressurizing mechanism will be described.

[0034] FIG. 3 is a schematic diagram showing an elastic film connected to the lower surface of the head body. As shown in FIGS. 2 and 3, an elastic film 110 that abuts against the back surface of the wafer W is connected to the lower surface 102a of the head body 102. The elastic film 110 includes a plurality of walls 114. The plurality of walls 114 are arranged at least along the circumferential direction of the polishing head 1. In the embodiment shown in FIG. 3, the plurality of walls 114 are arranged along the radial direction and the circumferential direction of the polishing head 1. The retainer ring 103 is arranged so as to surround the elastic film 110. A plurality of pressure chambers 116 arranged along the radial direction and the circumferential direction of the polishing head 1 are formed by these walls 114. The pressurizing mechanism as the pressing element has the pressure chambers 116 formed in the elastic film 110, and the fluid supply source (see FIG. 1) pressurizes the pressure chambers 116 by supplying fluid to the pressure chambers 116.

[0035] When the pressing element is a piezoelectric element, the polishing head 1 includes a plurality of piezoelectric elements mounted on the lower surface 102a of the head body 102 instead of the elastic film 110. These plurality of piezoelectric elements are arranged along the radial direction and the circumferential direction of the polishing head 1 in the same manner as the pressure chambers 116.

[0036] The polishing apparatus includes a pressing force control unit that can individually control the pressing forces of a plurality of pressing elements. In the present embodiment, the pressing force control unit is a pressure adjusting device 165 that individually adjusts the pressure in the pressure chambers 116. These pressure chambers 116 are connected to the pressure adjusting device (i.e., pressure regulator) 165 via a rotary joint 182, and fluid (e.g., air) is supplied through fluid lines 173 extending from the pressure adjusting device 165 to each pressure chamber 116. The pressure adjusting device 165 is connected to the control device 9 and can independently adjust the pressure in these pressure chambers 116.

[0037] The pressure adjusting device 165 can also form a negative pressure in the pressure chambers 116. Each pressure chamber 116 is also connected to an atmosphere release mechanism (not shown), and it is also possible to release the pressure chamber 116 to the atmosphere.

[0038] Figs. 4(a), 4(b), and 4(c) are diagrams showing examples of the film thickness distribution along the circumferential direction of the wafer at a position 3 mm inside from the outermost end of the wafer. More specifically, Fig. 4(a) shows the initial film thickness distribution before wafer polishing, Fig. 4(b) shows the film thickness distribution of the wafer when polished by a conventional polishing apparatus, and Fig. 4(c) exemplarily shows the film thickness distribution of the wafer when polished by the polishing apparatus of the present embodiment.

[0039] The position of the wafer angle of 0 degrees in Figs. 4(a) to 4(c) is set at the position of a characteristic portion that can identify the circumferential angle (or orientation) of the wafer. In the example shown in Figs. 4(a) to 4(c), the position of the wafer angle of 0 degrees is the position of a notch formed at the peripheral edge of the wafer.

[0040] In the example shown in Fig. 4(a), the initial film thickness distribution before polishing has a peak position at a wafer angle of 180 degrees and shows a variation in film thickness with a certain peak width and peak height. Possible causes for such an initial film thickness distribution include the characteristics of the film-forming apparatus and the influence of various processes for forming multilayer wiring.

[0041] When a wafer having the initial film thickness distribution shown in Fig. 4(a) is polished by a conventional polishing apparatus, polishing proceeds almost uniformly in the circumferential direction. Therefore, as shown in Fig. 4(b), a film thickness distribution almost the same as that before polishing remains on the polished wafer. Such variations in the film thickness distribution may cause the focus to be misaligned in the next exposure process, resulting in a decrease in the yield of semiconductor manufacturing.

[0042] As shown in Fig. 4(c), when a wafer having the initial film thickness distribution shown in Fig. 4(a) is polished by the polishing apparatus of the present embodiment, by selectively increasing the polishing rate at the peak position, it is possible to reduce the circumferential film thickness variation compared to the initial film thickness distribution.

[0043] An embodiment for improving the variation in the film thickness distribution in the circumferential direction of the wafer by controlling the polishing rate distribution in the circumferential direction of the wafer will be described. Fig. 5 is a diagram showing the positional relationship viewed from above the polishing surface. When a line connecting the center CP of the wafer W and the center CT of the polishing surface 2a is defined as an imaginary line VL, the polishing surface 2a can be divided into an upstream side of the imaginary line VL and a downstream side of the imaginary line VL with respect to its rotational direction. The upstream side and the downstream side of the imaginary line VL are, in other words, the upstream side and the downstream side of the wafer W with respect to the moving direction of the polishing surface 2a.

[0044] The circular S shown in Fig. 5 represents the rotation locus of the polishing surface 2a passing through the center CP of the wafer W. Among the two intersections of the tangent T at the wafer center CP of the circle S and the wafer circle, the upstream intersection is defined as the polishing head angle of 0 degrees, and the downstream intersection is defined as the polishing head angle of 180 degrees. Among the two intersections of the imaginary line VL and the wafer circle, the intersection on the polishing surface center side is defined as the polishing head angle of 270 degrees, and the intersection on the outer peripheral side of the polishing surface is defined as the polishing head angle of 90 degrees. The wafer circle is a circle representing the outermost end of the wafer W. Note that the polishing head angle is the initial rotation angle at the position of the polishing head 1 before polishing the wafer, more specifically, the position of the polishing head 1 when the polishing head 1 holding the wafer is disposed above the polishing pad 2. The rotation angle of the polishing head 1 is detected by a rotary encoder 41 (see Fig. 1) attached to the polishing head motor 18. The rotary encoder 41 is a rotation angle detector that detects the rotation angle of the polishing head 1.

[0045] In order to control the variation in film thickness in the circumferential direction of the wafer or the polishing pressure, it is necessary to grasp the film thickness at a specific position on the wafer. It is necessary to obtain the film thickness distribution on the wafer based on the reference position of the wafer angle (in this embodiment, the notch position). In order to obtain the film thickness distribution within the wafer surface during polishing, it is necessary to grasp the notch position of the wafer during polishing.

[0046] If it is assumed that the orientation of the wafer with respect to the polishing head 1 does not change from the start to the end of polishing, that is, the wafer does not shift in the circumferential direction with respect to the polishing head 1, the mounting angle of the wafer with respect to the polishing head 1 at the start of polishing is always kept constant, and by grasping the angle of the polishing head 1 by the rotary encoder 41 (see Fig. 1), the scanning locus of the film thickness sensor 60 on the wafer can be calculated from the positional relationship between the rotation angle of the polishing head 1 and the film thickness sensor 60 (described later), and thus it becomes possible to measure the film thickness at a specific position on the wafer.

[0047] However, due to the frictional force between the polishing pad 2 and the wafer, the wafer may shift in the circumferential direction within the polishing head 1. Also, it may be difficult to always keep the mounting angle of the wafer with respect to the polishing head constant at the start of polishing. Further, simply providing only one film thickness sensor for measuring a limited range of film thicknesses on the polishing table 3 as in the prior art, the measurement points on the wafer obtained while the polishing table 3 makes one rotation are limited to the arc-shaped passing locus of the sensor, which is insufficient for real-time measurement of the polishing film thickness.

[0048] In order to enhance the uniformity of the film thickness distribution, it is important to acquire accurate film thickness distribution information during the polishing of the wafer. Further, in order to acquire accurate film thickness distribution information, it is important to accurately identify the reference position of the wafer angle (in this embodiment, the notch position). Therefore, the polishing apparatus is configured to acquire accurate film thickness distribution information during the polishing of the wafer and enhance the uniformity of the film thickness distribution of the wafer. In this embodiment, the reference position of the circumferential angle of the wafer is the position of the notch. Hereinafter, a polishing apparatus having such a configuration will be described with reference to the drawings.

[0049] FIG. 6 is a diagram showing a plurality of film thickness sensors embedded in the polishing pad. As shown in FIG. 6, the polishing apparatus includes a plurality of film thickness sensors 60A to 60G that detect a plurality of physical quantities corresponding to the film thickness of the wafer W and output a plurality of signals corresponding to the film thickness of the wafer W. Hereinafter, in this specification, the film thickness sensors 60A to 60G may be simply referred to as the film thickness sensor 60 without distinction.

[0050] In FIG. 6, the circle S represents the rotation locus of the polishing surface 2a (i.e., the film thickness sensor 60D) passing through the center CP of the wafer W. The circle S1 represents the rotation locus of the polishing surface 2a (i.e., the film thickness sensor 60A) passing through the peripheral edge of the wafer W on the center side of the polishing pad 2. The circle S2 represents the rotation locus of the polishing surface 2a (i.e., the film thickness sensor 60G) passing through the peripheral edge of the wafer W on the outer peripheral side of the polishing pad 2. The peripheral edge of the wafer W is the outermost end of the wafer W where the notch Nt is formed and forms a wafer circle.

[0051] The circle S1 is a virtual inner edge that is centered on the center CT of the polishing pad 2 and contacts the center side of the polishing pad 2 with respect to the peripheral edge of the wafer W. The circle S2 is a virtual outer edge that contacts the outer peripheral side of the polishing pad 2 with respect to the peripheral edge of the wafer W. In other words, of the polishing surface 2a of the polishing pad 2, the inner edge of the region that contacts the peripheral edge of the wafer W is the circle S1, and the outer edge is the circle S2. The inner edge is defined as the inner region on the polishing pad 2 where the peripheral edge of the wafer W contacts (passes through). The outer edge is defined as the outer region on the polishing pad 2 where the peripheral edge of the wafer W contacts (passes through).

[0052] As shown in FIG. 6, the plurality of film thickness sensors 60A to 60G are arranged from the inner edge to the outer edge. Each time the polishing table 3 makes one rotation, the film thickness sensor 60A crosses the peripheral edge of the wafer W on the center side of the polishing pad 2, and each time the polishing table 3 makes one rotation, the film thickness sensor 60G crosses the peripheral edge of the wafer W on the outer peripheral side of the polishing pad 2.

[0053] In the embodiment shown in FIG. 6, between the film thickness sensor 60A and the film thickness sensor 60G, a plurality (more specifically, five) of film thickness sensors 60B to 60F are arranged. However, the number of film thickness sensors 60 arranged between the film thickness sensor 60A and the film thickness sensor 60G is not limited to this embodiment. At least one film thickness sensor 60 capable of measuring the film thickness distribution may be arranged across the region sandwiched between the circle S1 and the circle S2. In order to obtain more accurate film thickness distribution information, it is preferable that a plurality (many) of film thickness sensors 60 are arranged between the film thickness sensor 60A and the film thickness sensor 60G.

[0054] Each of the film thickness sensors 60A to 60G is configured to detect a physical quantity corresponding to the film thickness that changes according to the film thickness of the wafer W. As an example of the film thickness sensor 60, an optical sensor or an eddy current sensor can be mentioned. As the film thickness sensor 60, preferably, an optical sensor, and more preferably, a PSD (Position Sensitive Detector) sensor can be mentioned. As an example of the PSD sensor, GP2Y0A21YK manufactured by Sharp Corporation can be mentioned.

[0055] When the film thickness sensor 60 includes 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 to generate an eddy current, and outputs an eddy current signal.

[0056] When the film thickness sensor 60 includes a PSD sensor, the PSD sensor detects a voltage signal corresponding to the film thickness of the wafer W based on the triangulation method. More specifically, the PSD sensor emits light to the wafer W and detects a voltage corresponding to the angle of the light reflected from the wafer W. The reflection angle of the light varies according to the distance from the PSD sensor to the wafer W, and the magnitude of the voltage corresponding to the reflection angle also varies. Therefore, the PSD sensor detects a voltage corresponding to the film thickness of the wafer W based on the reflection angle of the light emitted to the wafer W and outputs a voltage signal.

[0057] As shown in FIG. 6, the control device 9 is electrically connected to each of these film thickness sensors 60A to 60G. The control device 9 is configured to measure the film thickness information of the wafer W based on a plurality of signals acquired from the film thickness sensors 60A to 60G. The storage device 9a of the control device 9 stores data indicating the correlation between the signals acquired from the film thickness sensor and the film thickness of the wafer W therein, and the processing device 9b measures the film thickness information of the wafer W based on the data stored in the storage device 9a.

[0058] In one embodiment, the thickness sensor 60 as a PSD sensor first detects a voltage corresponding to the thickness of a reference wafer W with a known thickness and sends a voltage signal to the control device 9. The storage device 9a of the control device 9 stores in advance data on the output voltage with respect to the thickness of the reference wafer W (thickness data).

[0059] Thereafter, during polishing, the thickness sensor 60 detects a voltage corresponding to the thickness of the wafer W to be polished and sends a voltage signal to the control device 9. The processing device 9b of the control device 9 calculates the difference between the voltage value corresponding to the thickness of the wafer W to be polished and the voltage value corresponding to the thickness of the reference wafer W with the voltage value corresponding to the thickness of the reference wafer W as a reference. The storage device 9a stores data (distance data) indicating the correlation between this difference and the distance between the thickness sensor 60 and the wafer W. Therefore, the processing device 9b determines the thickness of the wafer W to be polished based on the thickness data and the distance data.

[0060] The thickness sensors 60A to 60G are arranged in the polishing table 3 and are arranged in this order along the radial direction of the polishing table 3. The distance between the thickness sensors 60A to 60G is preferably larger than the diameter of the wafer W. Therefore, every time the polishing table 3 rotates once, the thickness sensor 60 detects a voltage corresponding to the thickness over the entire area of the wafer W. In other words, the thickness sensors 60A to 60G are arranged so as to extend from the inner edge to the outer edge on the polishing table 3 corresponding to the area where the wafer W on the polishing pad 2 passes. They do not necessarily have to be arranged along the radial direction of the polishing table 3. Also, instead of the thickness sensors 60A to 60G, one thickness sensor having a continuous measurement area capable of measuring the thickness over the entire area of the wafer W can also be used.

[0061] Due to the rotation of the polishing table 3, the film thickness sensor 60A moves along its rotation locus (see the circle S1 in FIG. 6), and detects a voltage corresponding to the film thickness of the peripheral portion of the wafer W on the rotation locus. In other words, when an arbitrary specific point on the peripheral portion of the wafer W moves to the position closest to the center CT of the polishing pad 2 (i.e., the position of the intersection of the wafer circle of the wafer W and the circle S1) due to the rotation of the polishing head 1, the film thickness sensor 60A detects the voltage at that specific point. The film thickness sensor 60A that has detected the voltage outputs a voltage signal to the control device 9.

[0062] Due to the rotation of the polishing table 3, the film thickness sensor 60D moves along its rotation locus (see the circle S in FIG. 6), detects the voltage at a specific point on the rotation locus including the center CP of the wafer W, and outputs a voltage signal to the control device 9.

[0063] Due to the rotation of the polishing table 3, the film thickness sensor 60G moves along its rotation locus (see the circle S2 in FIG. 6), and detects a voltage corresponding to the film thickness of the peripheral portion of the wafer W on the rotation locus. In other words, when an arbitrary specific point on the peripheral portion of the wafer W moves to the position farthest from the center CT of the polishing pad 2 (i.e., the position of the intersection of the wafer circle of the wafer W and the circle S2) due to the rotation of the polishing head 1, the film thickness sensor 60G detects the voltage at that specific point. The film thickness sensor 60G that has detected the voltage outputs a voltage signal to the control device 9.

[0064] As shown in FIG. 6, the notch Nt of the wafer W is formed at the peripheral portion of the wafer W. Therefore, at least one of the film thickness sensors 60A to 60G can surely detect the notch Nt of the wafer W every time the polishing table 3 makes one rotation. In particular, when the film thickness sensor 60 is a PSD sensor, since the PSD sensor is configured to detect a change in the distance from itself to the measurement object, the control device 9 can surely specify the position of the notch Nt of the wafer W. By using the PSD sensor, the control device 9 can measure the film thickness in a small area on the wafer W with the spot diameter of light. Therefore, the control device 9 can measure more detailed film thickness information.

[0065] Furthermore, based on the measured film thickness information, the control device 9 is configured to analyze the film thickness distribution information of the wafer W while identifying the notch position of the wafer W, and output visualization information of the film thickness distribution with the notch position as a reference position. The control device 9 calculates the position of the notch Nt during polishing (i.e., the angle of the notch Nt or the angle of the wafer W) to calculate the position on the wafer based on the notch Nt as a reference position for the position measured based on the film thickness sensor 60 during polishing.

[0066] The control device 9 associates the film thickness measured based on the film thickness sensor 60 with the measurement points on the wafer with the notch Nt as a reference. By using the film thickness sensors 60A to 60G, the control device 9 can measure the film thickness distribution of the entire area within the wafer W every time the wafer W makes one rotation. However, the film thickness distribution may be calculated as the average of the measured values during several rotations of the polishing table 3. Thereby, the accuracy of film thickness measurement can be improved.

[0067] According to the present embodiment, by providing a plurality of film thickness sensors 60, the control device 9 can acquire accurate film thickness distribution information including the position of the notch Nt of the wafer W. As a result, the control device 9 can perform mapping of the film thickness of the wafer W and output visualization information of an accurate film thickness distribution with the notch position as a reference position.

[0068] FIG. 7 is a diagram showing visualization information of the film thickness distribution output to the display device. In FIG. 7, an example of visualization information of the film thickness distribution is depicted. The control device 9 is electrically connected to a display device 70 (see FIG. 6) that projects the visualization information of the film thickness distribution.

[0069] The processing device 9b of the control device 9 compares the signal acquired from the film thickness sensor 60 with the data stored in the storage device 9a, measures the film thickness information of the wafer W, and identifies the position of the notch Nt of the wafer W. Further, the processing device 9b acquires film thickness distribution information from the film thickness information and the position of the notch Nt of the wafer W, analyzes this film thickness distribution information, and acquires visualization information of the film thickness distribution. As shown in FIG. 7, in the visualization information of the film thickness distribution, the surface of the wafer W is virtually divided into a plurality of regions, and the relative film thickness is visualized for each of the divided regions.

[0070] The control device 9 outputs the visualization information of the film thickness distribution of the wafer W as shown in FIG. 7 to the display device 70, and the display device 70 displays this visualization information. Therefore, the operator can grasp the film thickness of the wafer W through the display device 70.

[0071] During the polishing of the wafer W, each time the film thickness sensor 60 passes through the wafer W, it detects a physical quantity corresponding to the film thickness of the wafer W and sends a signal corresponding to the film thickness of the wafer W to the control device 9. Therefore, during the polishing of the wafer W, the control device 9 constantly analyzes the acquired film thickness distribution information and continuously updates the visualization information of the film thickness distribution output to the display device 70. As a result, the operator can grasp in real time the constantly changing film thickness of the wafer W during the polishing of the wafer W.

[0072] As shown in FIGS. 1 and 6, the control device 9 may include a median filter unit 9c that performs median filter processing on the signals acquired from each of the plurality of film thickness sensors 60. The median filter unit 9c performs median filter processing on the plurality of signals acquired from each of the plurality of film thickness sensors 60 to remove noise from the plurality of signals.

[0073] FIG. 8 is a diagram for explaining the median filter process. In the embodiment shown in FIG. 8, the median filter process will be described based on arbitrary numerical values. The median filter process is a noise removal process that extracts the median value among a set of multiple numerical values as data and suppresses sudden variations in the data. In FIG. 8, 11 measurement data are detected by a single film thickness sensor 60. For example, when the median filter unit 9c performs a median filter process on the measured values of the measurement data from the first to the fifth time, among the numerical values of 5.5, 4.5, 5.0, 7.5, and 4.9, the median value of 5.0 is adopted as the measured value.

[0074] When a PSD sensor is adopted as the film thickness sensor 60, in a reflection type distance measurement sensor such as a PSD sensor, noise is relatively likely to occur. In particular, in the wafer W on which wiring is formed, noise may occur in regions with different wiring heights. Since the median filter unit 9c can remove the noise of the measured value, especially when a PSD sensor is adopted as the film thickness sensor 60, the median filter unit 9c can effectively exert its function.

[0075] FIG. 9 is a diagram showing a flowchart including steps for outputting visualization information of the film thickness distribution. FIG. 9 shows a flowchart in the case where a PSD sensor is adopted as the film thickness sensor 60. As shown in step S101 of FIG. 9, the control device 9 acquires a signal (reference film thickness signal) corresponding to the film thickness of the reference wafer W detected by the film thickness sensor 60. The storage device 9a of the control device 9 stores film thickness data regarding the film thickness of the reference wafer W.

[0076] The control device 9 starts polishing the wafer W to be polished (see step S102), and acquires a signal (target film thickness signal) corresponding to the film thickness of the wafer W to be polished detected by the film thickness sensor 60 (see step S103). Based on the reference film thickness signal acquired in step S101, the target film thickness signal acquired in step S103, and the film thickness data stored in the storage device 9a, the control device 9 measures the film thickness information of the current wafer W to be polished (see step S104).

[0077] Based on the film thickness information measured in step S104, the control device 9 identifies the notch position, acquires and analyzes the film thickness distribution information of the wafer W to be polished (see step S105), and outputs visualization information of the film thickness distribution with the notch position as the reference position (see step S106).

[0078] As shown in step S201 of FIG. 9, the control device 9 may control the pressing force at a specific position on the wafer W by analyzing the film thickness distribution information of the wafer W and controlling a specific pressing element via the pressing force control unit. In order to improve the uniformity of the film thickness distribution of the wafer W, the control device 9 is based on the rotation angle of the polishing head 1 acquired from the rotary encoder 41 (see FIG. 1) as the rotation angle detector that detects the rotation angle of the polishing head 1, and the signal acquired from the film thickness sensor 60. Based on the measured film thickness information, the pressing force control unit (in this embodiment, the pressure adjusting device 165) is operated. By this operation, the control device 9 individually controls the pressing force of the pressing element (in this embodiment, the pressure of the fluid supplied to the pressure chamber 116) to actively polish the thick portion of the film of the wafer W or to actively polish the portions other than the thin portion of the film of the wafer W.

[0079] In order to control the pressing force at a specific position on the wafer W, in this embodiment, the pressure in the pressure chamber 116 divided at least along the circumferential direction of the polishing head is individually controlled, but the embodiment of the polishing head is not limited to this. Any polishing head having a pressing element capable of applying different polishing pressures to different regions in the circumferential direction of the wafer W can be used.

[0080] FIG. 10 is a diagram showing the relationship between a specific position on the wafer, the position of the notch, and the rotation angle of the polishing head. By measuring the film thickness of the wafer W with a film thickness measuring device (not shown) provided in the polishing apparatus or a film thickness measuring device (not shown) separate from the polishing apparatus, a specific position FT (a portion where the film thickness is particularly thick or a portion where the film thickness is particularly thin) on the wafer W may be specified in advance. In this case, the control device 9 determines the relationship between the specific position FT and the position of the notch Nt, and stores this relationship in the storage device 9a.

[0081] When the specific position FT on the wafer W is specified in advance, the control device 9 determines the relationship between the rotation angle of the polishing head 1 and the position of the notch Nt based on the signal sent from the rotary encoder 41 and the signal sent from the film thickness sensor 60. Since the relationship between the specific position FT and the position of the notch Nt is stored in the storage device 9a, the control device 9 specifies the angle (and the distance from the wafer center) of the specific position FT with respect to the rotation angle from the relationship between the rotation angle of the polishing head 1 and the position of the notch Nt, and controls the pressing element in the polishing head corresponding to the specific position FT to control the pressing force with respect to the specific position FT. Here, the rotation angle is the angle with respect to the fixed coordinate system of the reference direction RA. The reference direction RA is a direction fixed with respect to the polishing head 1 in order to determine the rotation angle of the polishing head 1.

[0082] Next, the case where the control device 9 specifies the specific position FT on the wafer W based on the signal detected by the film thickness sensor 60 will be described. When there is a measurement point (film thickness singularity point) where the film thickness is higher (or lower) than other measurement points among the film thickness information obtained from the film thickness sensor 60, based on the scanning locus of the film thickness sensor 60 on the wafer W and the rotation angle of the polishing head 1, the pressing element in the polishing head 1 corresponding to the specific position FT on the wafer W can be specified, and the pressing force can be controlled.

[0083] More preferably, as described above, the rotation angle of the polishing head 1 is obtained from the signal sent from the rotary encoder 41, and the position of the notch Nt is measured from the signal sent from the film thickness sensor 60. From the relationship between the position of the film thickness singularity on the scanning locus of the film thickness sensor 60 and the position of the notch Nt, and the relationship between the rotation angle of the polishing head 1 and the position of the notch Nt, the pressing element in the polishing head 1 corresponding to the specific position FT on the wafer W is specified. The reason is that there is a time delay from when the film thickness sensor 60 acquires a signal corresponding to the film thickness until the film thickness is calculated and the pressing force of a specific pressing element is controlled, and during this time, the wafer W may shift within the polishing head 1. Also, to measure the film thickness with higher accuracy, it is desirable to average the film thickness obtained while the wafer W rotates several times. In that case, since the time delay becomes even larger, it is desirable to specify the position of the notch Nt and then specify the position of the pressing element in the polishing head 1. According to the present embodiment, even if the wafer W shifts with respect to the polishing head 1 during polishing, it is possible to adjust the pressure of the pressing element in the polishing head 1 corresponding to the specific position FT on the wafer W to improve film thickness variation.

[0084] After executing step S201 in FIG. 9, the control device 9 ends the polishing of the wafer W (see step S203) when a predetermined polishing time is reached or when it receives an end point detection signal from the film thickness sensor 60 (see "YES" in step S202). If the predetermined polishing time has not been reached or the control device 9 has not received an end point detection signal from the film thickness sensor 60 (see "NO" in step S202), the process shown in step S103 is repeated.

[0085] FIG. 11 is a diagram for explaining an embodiment of correcting film thickness information based on the wear amount of the polishing pad. In the embodiment shown in FIG. 11, the film thickness sensor 60 is a PSD sensor. The control device 9 may correct the film thickness information based on the wear amount of the polishing pad 2. When the dresser 51 is brought into sliding contact with the polishing surface 2a of the polishing pad 2, the polishing pad 2 wears, and as a result, the distance between the film thickness sensor 60 and the wafer W changes (see FIG. 11). Since such a wear amount of the polishing pad 2 affects the measurement of the film thickness information of the wafer W, the processing device 9b of the control device 9 may correct the film thickness information of the wafer W based on the wear amount of the polishing pad 2.

[0086] The film thickness information of the wafer W is corrected as follows, for example. Prepare a plurality of polishing pads 2 with different wear amounts (i.e., different thicknesses), and a reference wafer W with a known film thickness. First, the control device 9 presses the reference wafer W against the polishing surface 2a of the initial polishing pad 2 with a wear amount of zero (i.e., not worn), and acquires the signal output by the film thickness sensor 60 at this time (the initial signal). Then, the control device 9 presses the reference wafer W against the polishing surface 2a of the polishing pads 2 with different wear amounts, and acquires the signal output by the film thickness sensor 60 at this time (the signal after wear). Note that the film thicknesses of the measured reference wafers W are all the same.

[0087] In this way, the control device 9 calculates the difference between the initial signal and the signal after wear, and associates the wear amount of the polishing pad 2 with this difference as the correction amount. This associated correction data is stored in the storage device 9a.

[0088] After the polishing of the wafer W is completed (see step S203), the dressing unit 50 dresses the polishing surface 2a of the polishing pad 2 with the dresser 51, and the control device 9 measures the thickness of the polishing pad 2 to measure (calculate) the wear amount of the polishing pad 2 (see step S301). The control device 9 corrects the film thickness information of the next wafer W to be polished based on the correction data stored in the storage device 9a. By such correction, the control device 9 can acquire more accurate film thickness information.

[0089] The above-described embodiments are described for the purpose of enabling those with ordinary knowledge in the technical field to which the present invention pertains to practice the present invention. Various modifications of the above embodiments can be naturally made by those skilled in the art, and the technical idea of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is construed in the broadest scope in accordance with the technical idea defined by the claims.

Description of Reference Numerals

[0090] 1 Polishing head 2 Polishing pad 2a Polishing surface 3 Polishing table 3a Table shaft 5 Polishing liquid supply nozzle 9 Control device 9a Storage device 9b Processing device 9c Median filter section 11 Polishing head shaft 13 Table motor 16 Head arm 18 Polishing head motor 27 Vertical movement mechanism 28 Bridge 39 Polishing head height sensor 41 Rotary encoder 50 Dressing unit 51 Dresser 52 Dresser shaft 55 Swing arm 56 Displacement sensor 57 Target plate 60A~60G Film thickness sensor 70 Display device 102 Head body 102a Lower surface 103 Retaining ring 110 Elastic film 114 Wall 116 Pressure chamber 165 Pressure adjustment device 182 Rotary joint

Claims

1. A polishing table that supports a polishing pad, A plurality of film thickness sensors embedded in the polishing table and outputting a plurality of signals corresponding to the film thickness of a substrate, A control device that measures the film thickness information of the substrate based on the plurality of signals acquired from the plurality of film thickness sensors, and is provided with, On the polishing pad, when defining the inner region where the peripheral portion of the substrate contacts as the inner edge portion and the outer region where the peripheral portion of the substrate contacts as the outer edge portion, the plurality of film thickness sensors are arranged from the inner edge portion to the outer edge portion, The control device, Each time the polishing table makes one rotation, for the signals at a specific time detected by the plurality of film thickness sensors, a specific film thickness sensor detects a signal corresponding to the notch position of the substrate, which is different from the signals detected by other film thickness sensors, By comparing the signals indicating the change in the distance to the substrate acquired from the plurality of film thickness sensors with the data indicating the correlation between the signals and the film thickness of the substrate, while specifying the notch position of the substrate based on the measured film thickness information, analyzing the film thickness distribution information of the substrate, and outputting visualization information of the film thickness distribution with the notch position as a reference position, a polishing apparatus.

2. The polishing apparatus according to claim 1, wherein each of the plurality of film thickness sensors includes a PSD sensor.

3. The control device includes a median filter unit that performs median filter processing on the plurality of signals acquired from each of the plurality of film thickness sensors, The median filter unit performs median filter processing on the plurality of signals acquired from each of the plurality of film thickness sensors to remove noise from the plurality of signals. The polishing apparatus according to claim 1 or claim 2.

4. The polishing apparatus is provided with a wear amount detection device that outputs a signal corresponding to the wear amount of the polishing pad, The control device, Based on the signal acquired from the wear amount detection device, measures the wear amount of the polishing pad, Based on the measured wear amount of the polishing pad, corrects the film thickness information. The polishing apparatus according to any one of claims 1 to 3.

5. The polishing apparatus is provided with a display device connected to the control device, The control device outputs the visualization information of the film thickness distribution to the display device. The polishing apparatus according to any one of claims 1 to 4.

6. The polishing apparatus according to claim 1, wherein the control device measures the film thickness information based on film thickness data with respect to the film thickness of a reference substrate, a reference film thickness signal corresponding to the film thickness of the reference substrate, and a target film thickness signal corresponding to the film thickness of the substrate to be polished.

7. A polishing table that supports a polishing pad, A polishing head having a plurality of pressing elements for pressing a substrate against a polishing surface of the polishing pad, A pressing force control unit capable of individually controlling the pressing forces of the plurality of pressing elements, A plurality of film thickness sensors embedded in the polishing table and outputting a plurality of signals corresponding to the film thickness of the substrate, A control device that measures the film thickness information of the substrate based on the signals acquired from the plurality of film thickness sensors, The plurality of pressing elements are arranged at least along the circumferential direction of the polishing head, When, on the polishing pad, an inner region where the peripheral edge of the substrate contacts is defined as an inner edge portion and an outer region where the peripheral edge of the substrate contacts is defined as an outer edge portion, the plurality of film thickness sensors are arranged from the inner edge portion to the outer edge portion, The control device, For each rotation of the polishing table, for the signals at a specific time detected by the plurality of film thickness sensors, a specific film thickness sensor detects a signal corresponding to the notch position of the substrate that is different from the signals detected by other film thickness sensors, The polishing apparatus compares a signal indicating a change in the distance to the substrate acquired from the plurality of film thickness sensors with data indicating a correlation between the signal and the film thickness of the substrate, identifies the notch position of the substrate based on the measured film thickness information, analyzes the film thickness distribution information of the substrate, and controls a specific pressing element via the pressing force control unit to control the pressing force at a specific position on the substrate.

8. The polishing apparatus includes a rotation angle detector that detects the rotation angle of the polishing head, The polishing apparatus according to claim 7, wherein the control device controls a specific pressing element via the pressing force control unit to control the pressing force at a specific position on the substrate based on the rotation angle of the polishing head acquired from the rotation angle detector and the measured film thickness information.

9. The control device, Identifies the notch position of the substrate based on the measured film thickness information, The polishing apparatus according to claim 8, wherein a specific position on the substrate is determined from the relationship between the rotation angle of the polishing head and the notch position, and the pressing force at the specific position on the substrate is controlled by controlling a specific pressing element via the pressing force control unit.

10. The control device identifies a specific position on the substrate based on the measured film thickness information, and controls a specific pressing element via the pressing force control unit based on the relationship between the rotation angle of the polishing head and the specific position on the substrate, thereby controlling the pressing force at the specific position on the substrate. The polishing apparatus according to claim 8.

11. The control device is configured to measure the film thickness information based on the film thickness data for the reference substrate, the reference film thickness signal corresponding to the film thickness of the reference substrate, and the target film thickness signal corresponding to the film thickness of the substrate to be polished. The polishing apparatus according to claim 7.

12. A method for outputting visualization information of the film thickness distribution of a substrate, wherein, on a polishing pad, when an inner region where the peripheral edge of the substrate contacts is defined as an inner edge portion and an outer region where the peripheral edge of the substrate contacts is defined as an outer edge portion, a plurality of signals corresponding to the film thickness of the substrate are acquired by a control device from a plurality of film thickness sensors arranged from the inner edge portion to the outer edge portion, the film thickness information of the substrate is measured by the control device based on the acquired plurality of signals, each time the polishing table makes one rotation, for the signals at a specific time detected by the plurality of film thickness sensors, a specific film thickness sensor detects a signal corresponding to the notch position of the substrate that is different from the signals detected by other film thickness sensors, the signals indicating the change in the distance to the substrate acquired from the plurality of film thickness sensors and the data indicating the correlation between the signals and the film thickness of the substrate are compared, and based on the measured film thickness information, the control device identifies the notch position of the substrate while analyzing the film thickness distribution information of the substrate, and outputs visualization information of the film thickness distribution with the notch position as a reference position.

13. The method according to claim 12, wherein a plurality of signals corresponding to the film thickness of the substrate are acquired from a plurality of PSD sensors.

14. The method according to claim 12 or claim 13, wherein the acquired plurality of signals are subjected to median filter processing to remove noise from the plurality of signals.

15. Obtain a signal corresponding to the wear amount of the polishing pad from a wear amount detection device, Measure the wear amount of the polishing pad based on the obtained signal, Correct the film thickness distribution information of the substrate based on the measured wear amount of the polishing pad, according to any one of claims 12 to 14.

16. Output the visualization information of the film thickness distribution to a display device, according to any one of claims 12 to 15.

17. Based on the film thickness data with respect to the film thickness of a reference substrate, the reference film thickness signal corresponding to the film thickness of the reference substrate, and the target film thickness signal corresponding to the film thickness of the substrate to be polished, measure the film thickness information by the control device, according to claim 12.

18. When, on the polishing pad, the inner region where the peripheral portion of the substrate contacts is defined as the inner edge portion and the outer region where the peripheral portion of the substrate contacts is defined as the outer edge portion, obtain a plurality of signals corresponding to the film thickness of the substrate from a plurality of film thickness sensors arranged from the inner edge portion to the outer edge portion by a control device, Measure the film thickness information of the substrate by the control device based on the obtained plurality of signals, For the signals at a specific time detected by the plurality of film thickness sensors each time the polishing table rotates once, a specific film thickness sensor detects a signal corresponding to the notch position of the substrate that is different from the signals detected by other film thickness sensors, Compare the signal indicating the change in the distance to the substrate obtained from the plurality of film thickness sensors with the data indicating the correlation between the signal and the film thickness of the substrate, and based on the measured film thickness information, while specifying the notch position of the substrate by the control device, analyze the film thickness distribution information of the substrate, and control at least a plurality of pressing elements arranged along the circumferential direction of the polishing head for pressing the substrate against the polishing surface of the polishing pad, so as to control the pressing force at a specific position on the substrate. A polishing method.

19. Obtain the rotation angle of the polishing head by a rotation angle detector that detects the rotation angle of the polishing head, Control the plurality of pressing elements based on the rotation angle of the polishing head obtained from the rotation angle detector and the measured film thickness information, so as to control the pressing force at a specific position on the substrate, according to the polishing method described in claim 18.

20. Based on the measured film thickness information, identify the notch position of the substrate, The polishing method according to claim 19, wherein a specific position on the substrate is determined from the relationship between the rotation angle of the polishing head and the notch position, and the pressing force at the specific position on the substrate is controlled by controlling the plurality of pressing elements.

21. Based on the measured film thickness information, identify a specific position on the substrate, The polishing method according to claim 19, wherein the pressing force at a specific position on the substrate is controlled by controlling the plurality of pressing elements based on the relationship between the rotation angle of the polishing head and the specific position on the substrate.

22. The polishing method according to claim 18, wherein the control device measures the film thickness information based on the film thickness data with respect to the film thickness of the reference substrate, the reference film thickness signal corresponding to the film thickness of the reference substrate, and the target film thickness signal corresponding to the film thickness of the substrate to be polished.

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