Grinding device and grinding method

Abstract

The present invention relates to a polishing apparatus and a polishing method. The polishing apparatus is provided with an operation control unit (9) that individually controls the pressure of each of a plurality of pressure chambers. The operation control unit (9) controls the pressure in the pressure chamber of the polishing head (1) corresponding to a specific position in such a manner as to reduce the difference between the film thickness value of the control object and the average film thickness value of the entire substrate.

Description

Technical Field

[0001] This invention relates to a grinding apparatus and a grinding method. Background Technology

[0002] Chemical mechanical polishing (CMP) is a known technique used in the manufacturing process of semiconductor components. A polishing apparatus for CMP includes: a polishing table that supports the polishing pad; and a polishing head for holding the wafer.

[0003] When polishing wafers 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 specified pressure. At this time, by moving the polishing table relative to the polishing head, the wafer slides into contact with the polishing surface to polish the wafer surface.

[0004] Furthermore, the wafer thickness distribution is obtained by detecting the signal corresponding to the wafer thickness using a film thickness sensor. The grinding endpoint is determined based on the wafer thickness distribution, or the pressure of multiple air bladders arranged concentrically on the grinding head is controlled. The film thickness sensor rotates together with the grinding stage, keeping the grinding head rotating as well.

[0005] Therefore, the path of the film thickness sensor across the wafer surface changes with each rotation of the polishing stage. As an indicator for controlling the pressure of each gasket, the film thickness measured at different measurement points in each concentric gasket is typically averaged to calculate the representative film thickness within each gasket. The film thickness distribution of the wafer is calculated based on signals obtained from different measurement points along the circumference, as an averaged value in the circumferential direction.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2015 / 163164

[0009] Patent Document 2: Japanese Patent Application Publication No. 2005-11977

[0010] (The problem the invention aims to solve)

[0011] In recent years, the requirements for film thickness uniformity have increased. Within a wafer region corresponding to a concentrically arranged array of gasbags, the film thickness fluctuates more significantly along the wafer radius. Consequently, even adjusting the pressure of the gasbags corresponding to this region cannot achieve a sufficiently high level of film thickness uniformity.

[0012] In recent years, the requirements for film thickness uniformity have increased. Therefore, it is necessary to further consider factors such as the characteristics of the film deposition apparatus, including the degree of circumferential variation in the initial film thickness of the wafer and the degree of circumferential variation in the amount of material removed during polishing, in order to manage and control the polishing process (for example, actively polishing the thickest areas of the wafer, or actively polishing areas other than the thinnest areas, to effectively improve the uniformity of the film thickness). Furthermore, sometimes existing methods struggle to keep the difference between the maximum and minimum film thickness within the wafer plane within acceptable limits. Summary of the Invention

[0013] Therefore, the object of the present invention is to provide a polishing apparatus and polishing method that can improve the uniformity of film thickness of wafers.

[0014] (Technical means used to solve the problem)

[0015] One method provides a polishing apparatus comprising: a polishing table supporting a polishing pad; a polishing head having a plurality of pressure chambers concentrically divided for pressing a substrate against a polishing surface of the polishing pad; a plurality of pressure adjusters connected to the plurality of pressure chambers; a film thickness sensor embedded in the polishing table and outputting a signal corresponding to the film thickness of the substrate; and an operation control unit that individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure adjusters. The operation control unit acquires information about a specific location that is part of the circumference of the substrate, and calculates a controllable film thickness value for a controllable area including the specific location and an average film thickness value for the entire substrate. The operation control unit controls the pressure in the pressure chamber of the polishing head corresponding to the specific location in a manner that reduces the difference between the controllable film thickness value and the average film thickness value for the entire substrate.

[0016] In one embodiment, the motion control unit determines the specific position based on the film thickness of the substrate measured before polishing.

[0017] In one embodiment, the motion control unit determines the maximum film thickness position and the minimum film thickness position based on the film thickness of the substrate measured before polishing, and the motion control unit determines at least one of the maximum film thickness position and the minimum film thickness position as the specific position.

[0018] In one embodiment, the motion control unit determines a maximum film thickness value and a minimum film thickness value based on the film thickness of the substrate measured before polishing. The motion control unit calculates the difference between the average film thickness value of the entire substrate and the maximum film thickness value, and the difference between the average film thickness value of the entire substrate and the minimum film thickness value. The motion control unit determines the position on the substrate where the film thickness value with the largest difference is obtained as the specific position.

[0019] In one approach, the controlled film thickness value corresponds to at least one of a maximum film thickness value and a minimum film thickness value determined based on the film thickness of the substrate measured before polishing.

[0020] In one approach, the film thickness value of the controlled object is the average of multiple film thickness values ​​within the controlled object region.

[0021] In one embodiment, the motion control unit measures the film thickness in the controlled object region including the specific location during grinding based on a signal output from the film thickness sensor, and controls the pressure in the pressure chamber of the grinding head corresponding to the specific location based on the measured film thickness.

[0022] In one embodiment, the motion control unit divides multiple pressing areas on the substrate, which are divided according to the multiple pressure chambers, into a specific pressing area including the controlled object area and other pressing areas other than the specific pressing area. The motion control unit calculates the average film thickness value of the other pressing areas based on the film thickness of the substrate. The motion control unit controls the pressure in the pressure chamber corresponding to the other pressing areas in a manner that reduces the difference between the average film thickness value of the other pressing areas and the average film thickness value of the entire substrate.

[0023] In one embodiment, the motion control unit acquires information about a reference position that is part of the circumference of a reference substrate different from the substrate. During the polishing of the reference substrate, the motion control unit detects a physical quantity corresponding to the film thickness of a region on the substrate including the reference position using the film thickness sensor. Based on multiple signals from the film thickness sensor, the motion control unit acquires multiple data corresponding to the film thickness of the reference substrate. The motion control unit associates each of the multiple data with the film thickness of the reference substrate at the time each of the multiple data is acquired.

[0024] In one embodiment, the motion control unit determines the reference position based on the film thickness of the reference substrate measured before polishing.

[0025] In one embodiment, the motion control unit controls at least one of the rotational speed of the grinding head and the rotational speed of the grinding table in such a manner that the film thickness sensor passes through the controlled object area.

[0026] In one embodiment, the motion control unit determines the relative angle between the reference position and the grinding head based on the relationship between the reference position of the substrate in the circumferential direction and the rotation angle of the grinding head, and the motion control unit controls at least one of the rotation speed of the grinding head and the rotation speed of the grinding table based on the determined relative angle.

[0027] One method provides a polishing technique in which a substrate is pressed against the polishing surface of a polishing pad using a polishing head having a plurality of pressure chambers concentrically divided into multiple pressure chambers. The polishing method obtains information about a specific location that is part of the circumference of the substrate, and calculates a controllable film thickness value for a controllable area including the specific location and an average film thickness value for the entire substrate. The pressure within the pressure chamber of the polishing head corresponding to the specific location is controlled in such a way that the difference between the controllable film thickness value and the average film thickness value for the entire substrate is reduced.

[0028] In one approach, the specific location is determined based on the film thickness of the substrate measured prior to polishing.

[0029] In one approach, based on the film thickness of the substrate measured before polishing, a maximum film thickness position for obtaining the maximum film thickness value and a minimum film thickness position for obtaining the minimum film thickness value are determined, and at least one of the maximum film thickness position and the minimum film thickness position is determined as the specific position.

[0030] In one approach, based on the film thickness of the substrate measured before polishing, a maximum film thickness value and a minimum film thickness value are determined, the difference between the average film thickness value of the entire substrate and the maximum film thickness value and the difference between the average film thickness value of the entire substrate and the minimum film thickness value are calculated, and the position on the substrate where the film thickness value with the largest difference is obtained is determined as the specific position.

[0031] In one approach, the controlled film thickness value corresponds to at least one of a maximum film thickness value and a minimum film thickness value determined based on the film thickness of the substrate measured before polishing.

[0032] In one approach, the film thickness value of the controlled object is the average of multiple film thickness values ​​within the controlled object region.

[0033] In one approach, the film thickness of the controlled object region containing the specific location in the grinding process is measured based on the output signal of the film thickness sensor, and the pressure in the pressure chamber of the grinding head corresponding to the specific location is controlled based on the measured film thickness.

[0034] In one approach, a plurality of pressing regions on the substrate, divided according to the plurality of pressure chambers, are divided into a specific pressing region including the controlled object region and other pressing regions other than the specific pressing region. The average film thickness of the other pressing regions is calculated based on the film thickness of the substrate, and the pressure in the pressure chamber corresponding to the other pressing regions is controlled in a manner that reduces the difference between the average film thickness of the other pressing regions and the average film thickness of the entire substrate.

[0035] In one approach, information about a reference position that is part of the circumference of a reference substrate different from the substrate is obtained. During the polishing of the reference substrate, a physical quantity corresponding to the film thickness of a region on the substrate containing the reference position is detected by the film thickness sensor. Based on multiple signals sent from the film thickness sensor, multiple data corresponding to the film thickness of the reference substrate are obtained, and each of the multiple data is associated with the film thickness of the reference substrate at the time when each of the multiple data is obtained.

[0036] In one approach, the reference position is determined based on the film thickness of the reference substrate measured prior to polishing.

[0037] In one approach, at least one of the rotational speed of the grinding head and the rotational speed of the grinding table is controlled by rotating the grinding table that supports the grinding pad, such that the film thickness sensor passes through the controlled object area.

[0038] In one approach, the relative angle between the reference position and the grinding head is determined based on the relationship between the reference position of the substrate in the circumferential direction and the rotation angle of the grinding head, and at least one of the rotation speed of the grinding head and the rotation speed of the grinding table is controlled based on the determined relative angle.

[0039] One method provides a polishing apparatus comprising: a polishing table supporting a polishing pad; a polishing head having a plurality of pressure chambers concentrically divided for pressing a substrate against a polishing surface of the polishing pad; a plurality of pressure adjusters connected to the plurality of pressure chambers; a film thickness sensor embedded in the polishing table and outputting a signal corresponding to the film thickness of the substrate; and an action control unit that individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure adjusters. The motion control unit determines a maximum film thickness value and a minimum film thickness value from the film thickness of the substrate obtained by the film thickness sensor during the grinding of the substrate. The motion control unit determines at least one of a pressure chamber corresponding to the position of the substrate where the maximum film thickness value is detected and a pressure chamber corresponding to the position of the substrate where the minimum film thickness value is detected. When controlling the pressure of the pressure chamber associated with the maximum film thickness value, the motion control unit controls the pressure of the pressure chamber associated with the maximum film thickness value in such a way that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate. When controlling the pressure of the pressure chamber associated with the minimum film thickness value, the motion control unit controls the pressure of the pressure chamber associated with the minimum film thickness value in such a way that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value is higher than the average film thickness value of the entire substrate.

[0040] In one embodiment, the motion control unit determines the maximum film thickness value and the minimum film thickness value based on the film thickness of the substrate obtained at certain time intervals during the grinding of the substrate.

[0041] In one embodiment, the motion control unit calculates the grinding speed during grinding based on the film thickness of the substrate obtained by the film thickness sensor. Based on the grinding speed, the motion control unit calculates the change in the film thickness of the substrate between the acquisition time of the film thickness obtained by the film thickness sensor at each measurement point on the substrate and a reference time. The motion control unit uses the change as a correction value to correct the film thickness of the substrate obtained during grinding of the substrate at the time interval. Based on the corrected film thickness of the substrate, the motion control unit determines the maximum film thickness value and the minimum film thickness value.

[0042] In one embodiment, when the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, the motion control unit pre-determines, by setting a processing scheme, whether to control the pressure chamber associated with the maximum film thickness value in such a way that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate, or to control the pressure chamber associated with the minimum film thickness value in such a way that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value is higher than the average film thickness value of the entire substrate.

[0043] In one embodiment, when the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, the operation control unit compares a first difference between the maximum film thickness value and the average film thickness value of the entire substrate and a second difference between the minimum film thickness value and the average film thickness value of the entire substrate. If the first difference is greater than the second difference, the operation control unit controls the pressure of the pressure chamber associated with the maximum film thickness value in such a way that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate. If the second difference is greater than the first difference, the operation control unit controls the pressure of the pressure chamber associated with the minimum film thickness value in such a way that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value is higher than the average film thickness value of the entire substrate.

[0044] In one embodiment, when the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, the motion control unit compares a first difference between the maximum film thickness value and the average film thickness value within the pressing area corresponding to the maximum film thickness value, and a second difference between the minimum film thickness value and the average film thickness value within the pressing area corresponding to the minimum film thickness value. If the first difference is greater than the second difference, the motion control unit controls the pressure of the pressure chamber associated with the maximum film thickness value in such a way that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate. If the second difference is greater than the first difference, the motion control unit controls the pressure of the pressure chamber associated with the minimum film thickness value in such a way that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value is higher than the average film thickness value of the entire substrate.

[0045] One method provides a polishing method in which a substrate is pressed against the polishing surface of a polishing pad using a polishing head having a plurality of pressure chambers concentrically divided into multiple pressure chambers. A maximum film thickness value and a minimum film thickness value are determined based on the film thickness of the substrate obtained during polishing. At least one of a pressure chamber corresponding to the position of the substrate where the maximum film thickness value is detected and a pressure chamber corresponding to the position of the substrate where the minimum film thickness value is detected is determined. When controlling the pressure of the pressure chamber associated with the maximum film thickness value, the pressure of the pressure chamber associated with the maximum film thickness value is controlled such that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate. When controlling the pressure of the pressure chamber associated with the minimum film thickness value, the pressure of the pressure chamber associated with the minimum film thickness value is controlled such that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value is higher than the average film thickness value of the entire substrate.

[0046] In one approach, during the grinding of the substrate, the maximum film thickness value and the minimum film thickness value are determined based on the film thickness of the substrate obtained at certain time intervals.

[0047] In one approach, the grinding speed during grinding is calculated based on the film thickness of the substrate. Based on the grinding speed, the change in the film thickness of the substrate between the time of obtaining the film thickness at each measurement point on the substrate and a reference time is calculated. The change is used as a correction value to correct the film thickness of the substrate obtained during grinding of the substrate at the time interval. The maximum film thickness value and the minimum film thickness value are determined based on the corrected film thickness of the substrate.

[0048] In one approach, when the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, a pre-set processing scheme determines whether to control the pressure of the pressure chamber associated with the maximum film thickness value in such a way that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate, or to control the pressure of the pressure chamber associated with the minimum film thickness value in such a way that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value is higher than the average film thickness value of the entire substrate.

[0049] In one approach, when the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, a first difference between the maximum film thickness value and the average film thickness value of the entire substrate and a second difference between the minimum film thickness value and the average film thickness value of the entire substrate are compared. If the first difference is greater than the second difference, the pressure of the pressure chamber associated with the maximum film thickness value is controlled such that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate. If the second difference is greater than the first difference, the pressure of the pressure chamber associated with the minimum film thickness value is controlled such that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value is higher than the average film thickness value of the entire substrate.

[0050] In one approach, when the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, a first difference between the maximum film thickness value and the average film thickness value within the pressing area corresponding to the maximum film thickness value and a second difference between the minimum film thickness value and the average film thickness value within the pressing area corresponding to the minimum film thickness value are compared. If the first difference is greater than the second difference, the pressure of the pressure chamber associated with the maximum film thickness value is controlled such that the average film thickness value of the substrate corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire substrate. If the second difference is greater than the first difference, the pressure of the pressure chamber associated with the minimum film thickness value is controlled such that the average film thickness value of the substrate corresponding to the pressure chamber associated with the minimum film thickness value is higher than the average film thickness value of the entire substrate.

[0051] One approach provides a polishing method in which a substrate is pressed against the polishing surface of a polishing pad using a polishing head having a plurality of pressure chambers including specific pressure chambers. The polishing method includes: a first polishing step of polishing the substrate under first polishing conditions; and a second polishing step of polishing the substrate under second polishing conditions determined based on a first polishing profile, the first polishing profile being obtained by pre-polishing a substrate different from the substrate under the first polishing conditions, and the first polishing profile being along a radial direction of a specific region of the substrate corresponding to the specific pressure chambers, the second polishing conditions including polishing conditions pre-determined to form a second polishing profile having a distribution opposite to that of the first polishing profile, the second polishing step being performed after the first polishing step.

[0052] In one embodiment, the specific pressure chamber includes an edge pressure chamber that presses against the outermost periphery of the substrate.

[0053] In one embodiment, the second grinding conditions comprise grinding conditions determined by adjusting the pressure of a pressure chamber other than the specific pressure chamber.

[0054] In one embodiment, the second polishing conditions comprise polishing conditions determined by adjusting the pressure of the adjacent pressure chambers of the edge pressure chambers adjacent to the outermost periphery of the substrate being pressed.

[0055] In one embodiment, the second polishing conditions comprise polishing conditions determined by adjusting the pressing pressure of a retaining ring configured to surround the outermost periphery of the substrate relative to the polishing surface.

[0056] In one embodiment, the first polishing condition includes polishing conditions for polishing the substrate while feedback-controlling the pressure of each of the plurality of pressure chambers based on the film thickness of the substrate corresponding to each of the plurality of pressure chambers as measured using a film thickness sensor during polishing.

[0057] In one approach, the substrate is polished under the first polishing conditions, and after a predetermined switching condition is met, the substrate is polished under the second polishing conditions.

[0058] In one approach, as the switching condition, the process switches from the first grinding condition to the second grinding condition when the difference between the maximum and minimum film thickness in the specific region significantly exceeds a predetermined threshold.

[0059] In one approach, the switching condition is based on the time required to eliminate the difference between the maximum and minimum film thicknesses of the specific region by grinding under the second grinding condition and the remaining grinding time until the final target film thickness is reached, switching from the first grinding condition to the second grinding condition.

[0060] In one embodiment, the specific pressure chamber includes an edge pressure chamber that presses against the outermost periphery of the substrate, the pressure of the edge pressure chamber being controlled based on the second polishing conditions, and the pressure of other pressure chambers besides the edge pressure chamber being controlled based on the first polishing conditions.

[0061] (The effect of the invention)

[0062] By controlling the pressure within the pressure chamber of a polishing head corresponding to a control object region containing specific locations for planarizing the film thickness of the wafer, the uniformity of the film thickness of the wafer can be improved.

[0063] The polishing method includes a second polishing step of polishing the substrate under second polishing conditions. By polishing the substrate in the second polishing step, the uniformity of film thickness in a specific area of ​​the wafer can be improved. Attached Figure Description

[0064] Figure 1This is a schematic diagram illustrating one embodiment of the grinding apparatus.

[0065] Figure 2 This is a cross-sectional view of the grinding head.

[0066] Figure 3 This is a diagram showing an example of the spectrum generated by the motion control unit.

[0067] Figure 4 This is a diagram illustrating an example of a process for obtaining multiple reference spectra.

[0068] Figure 5 It is a diagram showing multiple pressing areas of a wafer divided by multiple pressure chambers.

[0069] Figure 6 It is a diagram showing the grinding profile of a wafer when the wafer is ground under the first grinding conditions.

[0070] Figure 7 This is a diagram representing the second grinding condition.

[0071] Figure 8 It is a graph showing the polishing rate of wafers polished under the first polishing conditions and the second polishing conditions.

[0072] Figure 9 This diagram illustrates an example of the process of polishing a wafer.

[0073] Figure 10 This is a diagram illustrating an example of a process that correlates a reference spectrum with the corresponding film thickness.

[0074] Figure 11 This diagram illustrates an example of the process of polishing a wafer.

[0075] Figure 12 This is a diagram showing that the chip is divided into multiple pressing areas.

[0076] Figure 13 This is a diagram showing a groove detection device.

[0077] Figure 14A This is a diagram showing the movement path of a film thickness sensor across the surface of a wafer.

[0078] Figure 14B This is a diagram showing the movement path of a film thickness sensor across the surface of a wafer.

[0079] Figure 15A This is a diagram used to illustrate the effect of the grinding process in this embodiment.

[0080] Figure 15B This is a diagram used to illustrate the effect of the grinding process in this embodiment.

[0081] Figure 16 This is a flowchart illustrating the pressure control within the pressure chamber implemented through the motion control unit.

[0082] Figure 17 This is a diagram used to illustrate the effect of the grinding process in other embodiments.

[0083] Figure 18 This is a diagram showing the process of correcting the film thickness value through the motion control unit. Detailed Implementation

[0084] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0085] Figure 1 This is a schematic diagram illustrating one embodiment of the grinding apparatus. (As shown) Figure 1 As shown, the polishing apparatus includes: a polishing table 3 supporting a polishing pad 2; a polishing head 1 pressing a wafer W (substrate, etc.) with a film onto the polishing pad 2; a table motor 6 for rotating the polishing table 3; a polishing slurry supply nozzle 5 for supplying polishing slurry, such as slurry, to the polishing pad 2; a film thickness sensor 40 (in this embodiment, an optical film thickness sensor 40) for measuring the film thickness of the wafer W; and an operation control unit 9 for controlling the operation of the polishing apparatus. The upper surface of the polishing pad 2 forms the polishing surface 2a of the polishing wafer W.

[0086] The grinding head 1 is connected to the head shaft 10, which is connected to a grinding head motor (not shown) via a belt or other connecting mechanism. The grinding head motor causes the grinding head 1 and the head shaft 10 to rotate together in the direction indicated by the arrow. The grinding table 3 is connected to the table motor 6, which is configured to rotate the grinding table 3 and the grinding pad 2 in the direction indicated by the arrow.

[0087] The wafer W is polished as shown below. While the polishing table 3 and polishing head 1 are in... Figure 1 The polishing head rotates in the direction indicated by the arrow, supplying polishing slurry from the polishing slurry supply nozzle 5 to the polishing surface 2a of the polishing pad 2 on the polishing table 3. The wafer W rotates around the head shaft 10 via the polishing head 1, and simultaneously, with polishing slurry present on the polishing pad 2, the wafer W is pressed against the polishing surface 2a of the polishing pad 2 by the polishing head 1. The polishing table 3 rotates with its center CP as its center. The surface of the wafer W is polished by the chemical action of the polishing slurry and the mechanical action of the abrasive particles contained in the polishing slurry or the polishing pad 2.

[0088] The motion control unit 9 comprises at least one computer. The motion control unit 9 includes: a storage device 9a storing a program; and a processing unit 9b executing calculations according to the commands contained in the program. The processing unit 9b includes a CPU (Central Processing Unit) or GPU (Graphics Processing Unit) that performs calculations according to the commands contained in the program stored in the storage device 9a. The storage device 9a includes: a main storage device (e.g., random access memory) accessible by the processing unit 9b; and an auxiliary storage device (e.g., a hard disk drive or solid-state drive) for storing data and programs.

[0089] The motion control unit 9 is electrically connected to the film thickness sensor 40. In this embodiment, the film thickness sensor 40 guides light to the surface of the wafer W, detects the reflected light from the wafer W, and outputs a signal corresponding to the film thickness of the wafer W to the motion control unit 9. The motion control unit 9 determines the film thickness of the wafer W based on the signal sent from the film thickness sensor 40 (more specifically, the intensity measurement data of the reflected light from the wafer W).

[0090] The film thickness sensor 40 in this embodiment is an optical film thickness sensor; however, any other film thickness sensor can be used as long as the film thickness of the wafer W can be measured by the motion control unit 9. In other words, the film thickness sensor 40 is a sensor that detects a physical quantity related to the film thickness of the wafer W. One example of the film thickness sensor 40 could be an eddy current sensor. An eddy current sensor generates eddy currents by passing magnetic flux through the conductive film of the wafer W using its sensor coil, detects the eddy currents corresponding to the film thickness of the wafer W, and outputs an eddy current signal. The motion control unit 9 determines the film thickness of the wafer W based on this eddy current signal.

[0091] The film thickness sensor 40 of this embodiment includes a light source 44 that emits light, a beam splitter 47, and an optical sensor head 7 connected to the light source 44 and the beam splitter 47. The optical sensor head 7, the light source 44, and the beam splitter 47 are mounted on the polishing table 3 and rotate integrally with the polishing table 3 and the polishing pad 2. The position of the optical sensor head 7 is the position through which it passes the surface of the wafer W on the polishing pad 2 each time the polishing table 3 and the polishing pad 2 rotate once.

[0092] The storage device 9a stores within it a program for generating the spectrum described later and detecting the film thickness of the wafer W. Light emitted from the light source 44 is transmitted to the optical sensor head 7 and guided from the optical sensor head 7 to the surface of the wafer W. The light is reflected from the surface of the wafer W, and the reflected light from the surface of the wafer W is received by the optical sensor head 7 and sent to the beam splitter 47. The beam splitter 47 decomposes the reflected light according to wavelength. In this way, the film thickness sensor 40 detects the intensity of the reflected light at each wavelength and sends the intensity measurement data of the reflected light to the motion control unit 9.

[0093] Figure 2 This is a cross-sectional view of the grinding head. (For example...) Figure 2As shown, the polishing head 1 includes: an elastic membrane 65 for pressing the wafer W onto the polishing surface 2a of the polishing pad 2; a head body 21 for holding the elastic membrane 65; an annular drive ring 62 disposed below the head body 21; and an annular retaining ring 60 fixed to the lower surface of the drive ring 62.

[0094] An elastic diaphragm 65 is mounted on the lower part of the head body 21. The head body 21 is fixed to the end of the head shaft 10, and the head body 21, elastic diaphragm 65, drive ring 62, and retaining ring 6 are configured to rotate integrally with respect to the rotation of the head shaft 10. The retaining ring 60 and drive ring 62 are configured to move up and down relative to the head body 21. The head body 21 is formed of resin such as engineering plastic (e.g., PEEK).

[0095] The lower surface of the elastic membrane 65 forms the substrate pressing surface 65a of the wafer W, which is pressed against the polishing surface 2a of the polishing pad 2. The retaining ring 60 is arranged to surround the substrate pressing surface 65a, and the wafer W is surrounded by the retaining ring 60. Four pressure chambers 70, 71, 72, and 73 are provided between the elastic membrane 65 and the head body 21.

[0096] Pressure chamber 70 is a central circular pressure chamber located in the center, pressure chamber 73 is an outer ring-shaped edge pressure chamber located on the outermost periphery, and pressure chambers 71 and 72 are intermediate pressure chambers located between pressure chamber 70 and pressure chamber 73, respectively.

[0097] Pressure chambers 70, 71, 72, and 73 are formed by the elastic membrane 65 and the head body 21. The central pressure chamber 70 is circular, while the other pressure chambers 71, 72, and 73 are annular. These pressure chambers 70, 71, 72, and 73 are arranged (divided) in concentric circles. In this embodiment, the elastic membrane 65 forms four pressure chambers 70 to 73; however, the number of pressure chambers described above is illustrative and can be varied appropriately.

[0098] Gas delivery lines F1, F2, F3, and F4 are connected to pressure chambers 70, 71, 72, and 73, respectively. One end of each gas delivery line F1, F2, F3, and F4 is connected to a compressed gas supply source (not shown) provided as a utility in a factory equipped with a polishing device. Compressed gases, such as compressed air, can be supplied to pressure chambers 70, 71, 72, and 73 via gas delivery lines F1, F2, F3, and F4, respectively. By supplying compressed gas to pressure chambers 70-73, the elastic diaphragm 65 expands, and the compressed gas in pressure chambers 70-73 presses the wafer W against the polishing surface 2a of the polishing pad 2 via the elastic diaphragm 65. Pressure chambers 70-73 function as actuators for pressing the wafer W against the polishing surface 2a of the polishing pad 2.

[0099] The retaining ring 60 is disposed around the elastic film 65 and is an annular member that contacts the polishing surface 2a of the polishing pad 2. The retaining ring 60 is configured to surround the outermost periphery (peripheral portion) of the wafer W, which can prevent the wafer from being ejected from the polishing head 1 during the polishing of the wafer W, and adjust the elastic movement (rebound) of the polishing pad 2 to adjust the film thickness distribution at the outermost periphery of the wafer W.

[0100] The upper part of the drive ring 62 is connected to the annular retaining ring pressing device 80. The retaining ring pressing device 80 applies a downward load to the entire upper surface 60b of the retaining ring 60 via the drive ring 62, thereby pressing the lower surface 60a of the retaining ring 60 against the grinding surface 2a of the grinding pad 2.

[0101] The retaining ring pressing device 80 includes: an annular piston 81 fixed to the upper part of the drive ring 62; and an annular rolling diaphragm 82 connected to the upper surface of the piston 81. A retaining ring pressure chamber 83 is formed inside the rolling diaphragm 82. The retaining ring pressure chamber 83 is connected to the aforementioned compressed gas supply source via a gas delivery line F5. Compressed gas is supplied to the retaining ring pressure chamber 83 through the gas delivery line F5.

[0102] When compressed gas is supplied from the aforementioned compressed gas supply source to the retaining ring pressure chamber 83, the rolling diaphragm 82 presses the piston 81 downwards. The piston 81 presses down the drive ring 62, which in turn presses the entire retaining ring 60 downwards. Thus, the retaining ring pressing device 80 presses the lower surface 60a of the retaining ring 60 against the grinding surface 2a of the grinding pad 2. The drive ring 62 is detachably connected to the retaining ring pressing device 80. In one embodiment, the retaining ring pressing device 80 may also have a structure in which the lower surface 60a of the retaining ring 60 is pressed against the grinding surface 2a of the grinding pad 2 by applying the downward force of the grinding head 1 to the retaining ring 60.

[0103] Gas delivery lines F1, F2, F3, F4, and F5 extend via a rotary joint 25 mounted on the head shaft 10. The grinding apparatus further includes pressure regulators R1, R2, R3, R4, and R5, which are respectively located on the gas delivery lines F1, F2, F3, F4, and F5. Compressed gas from the compressed gas supply source is independently supplied to pressure chambers 70-73 and the retaining ring pressure chamber 83 via pressure regulators R1 to R5. Pressure regulators R1 to R5 are configured to regulate the pressure of the compressed gas in pressure chambers 70-73 and the retaining ring pressure chamber 83. Pressure regulators R1 to R5 are connected to the operation control unit 9.

[0104] Pressure regulators R1 to R5 allow independent changes in the internal pressures of pressure chambers 70 to 73 and the retaining ring pressure chamber 83. This allows for independent adjustment of the pressing pressure of the wafer W relative to the polishing surface 2a at four corresponding regions: the central portion, the inner middle portion, the outer middle portion, and the edge portion, as well as the pressing pressure of the retaining ring 60 on the polishing pad 2. Gas delivery lines F1, F2, F3, F4, and F5 are also connected to atmospheric opening valves (not shown), allowing the pressure chambers 70 to 73 and the retaining ring pressure chamber 83 to be opened to the atmosphere. In this embodiment, the elastic membrane 65 forms four pressure chambers 70 to 73; however, in another embodiment, the elastic membrane 65 may form fewer or more pressure chambers than four.

[0105] Figure 3 This is a diagram showing an example of the spectrum generated by the motion control unit. Figure 3 In the diagram, the horizontal axis represents the wavelength of light reflected from the wafer, and the vertical axis represents the relative reflectivity derived from the intensity of the reflected light. Relative reflectivity is an index representing the intensity of reflected light and is the ratio of the light intensity to a specified reference intensity. At each wavelength, by dividing the light intensity (measured intensity) by the specified reference intensity, unwanted noise such as fluctuations in the intensity inherent in the optical system and the light source can be removed from the measured intensity.

[0106] The reference intensity is the intensity of light measured in advance for each wavelength, while the relative reflectance is calculated for each wavelength. Specifically, the relative reflectance is obtained by dividing the intensity (measured intensity) of light at each wavelength by the corresponding reference intensity.

[0107] The motion control unit 9 is configured to generate a spectrum of reflected light from the intensity measurement data of the reflected light. The spectrum of reflected light is represented as a curve (i.e., a spectroscopic waveform) showing the relationship between the wavelength and intensity of the reflected light. The intensity of the reflected light can also be represented as a relative value such as reflectivity or relative reflectivity.

[0108] In actual grinding, the corrected measured intensity is obtained by subtracting the black level (the background intensity obtained under the condition of light shielding) from the measured intensity. Then, the corrected reference intensity is obtained by subtracting the aforementioned black level from the reference intensity. Finally, the relative reflectance is obtained by dividing the corrected measured intensity by the corrected reference intensity. Specifically, the relative reflectance R(λ) can be obtained using the following formula (1).

[0109] [Mathematical Expression 1]

[0110]

[0111] Where λ is the wavelength of light reflected from the substrate, E(λ) is the intensity at wavelength λ, B(λ) is the reference intensity at wavelength λ, and D(λ) is the background intensity (black level) at wavelength λ measured under light-shielding conditions.

[0112] The motion control unit 9 generates data from the intensity measurement data of the reflected light, such as... Figure 3 The spectrum shown is shown. Furthermore, the motion control unit 9 determines the film thickness of the wafer W from the spectrum of the reflected light. The spectrum of the reflected light varies with the film thickness of the wafer W. Therefore, the motion control unit 9 can determine the film thickness of the wafer W from the spectrum of the reflected light. Hereinafter, in this specification, the spectrum generated from the reflected light from the polished wafer W will be referred to as the measurement spectrum.

[0113] The motion control unit 9 is configured to determine the film thickness by comparing the measured spectrum (i.e., measurement data) with multiple reference spectra (i.e., reference data). The motion control unit 9 determines the reference spectrum whose shape is closest to the measured spectrum by comparing the measured spectrum generated during grinding with multiple reference spectra, and obtains the film thickness associated with the determined reference spectrum. The reference spectrum whose shape is closest to the measured spectrum is the spectrum with the smallest difference in relative reflectance between the reference spectrum and the measured spectrum.

[0114] Multiple reference spectra are obtained in advance by grinding a reference wafer that is identical to or has the same initial film thickness as the wafer to be ground (hereinafter, in this specification, wafer W is equivalent to the wafer to be ground). The wafer to be ground is a wafer different from the reference wafer, and is the wafer for which a film thickness planarization process is performed. The reference wafer is the wafer for which a process is performed to associate the reference spectra with the corresponding film thicknesses.

[0115] Each reference spectrum can be correlated with the film thickness at which it was obtained. That is, each reference spectrum is obtained at a different film thickness, and multiple reference spectra correspond to multiple different film thicknesses. Therefore, the current film thickness can be estimated by determining the reference spectrum whose shape is closest to the measured spectrum.

[0116] Figure 4 This diagram illustrates an example of the process for obtaining multiple reference spectra. First, a reference wafer with the same or equal film thickness as wafer W is prepared. The reference wafer is then transferred to the film thickness measuring device 170 (reference...). Figure 1 The initial film thickness of the reference wafer is measured by the film thickness measuring device 170 (refer to step S101). The film thickness measuring device 170 is electrically connected to the motion control unit 9.

[0117] Next, while supplying the polishing slurry to the polishing head 1, the reference wafer is polished (see step S102). During the polishing of the reference wafer, light is irradiated on the surface of the reference wafer to obtain the spectrum of the reflected light from the reference wafer (i.e., the reference spectrum) (see step S103).

[0118] The reference spectrum is obtained every time the polishing table 3 rotates once. Therefore, multiple reference spectra are obtained during the polishing of the reference wafer. After the polishing of the reference wafer is completed, the reference wafer is transported again to the film thickness measuring device 170 to measure the film thickness of the polished reference wafer (i.e., the final film thickness) (refer to step S104).

[0119] When the polishing rate of the reference wafer is constant, the film thickness decreases linearly along with the polishing time. The polishing rate can be calculated by dividing the difference between the initial film thickness and the final film thickness by the polishing time to reach the final film thickness. As described above, the reference spectra are periodically acquired every revolution of the polishing stage 3. Therefore, the polishing time for acquiring each reference spectrum can be calculated from the rotation speed of the polishing stage 3. Thus, the motion control unit 9 determines the film thickness corresponding to each reference spectrum (refer to step S105).

[0120] Each reference spectrum can be associated with (or combined with) the corresponding film thickness. Therefore, by determining the reference spectrum whose shape is closest to the measured spectrum during the grinding of the wafer W, the motion control unit 9 can determine the current film thickness of the wafer W from the film thickness associated with that reference spectrum.

[0121] The following describes the process of polishing the wafer W to be polished. First, it is necessary to determine the first polishing conditions (in other words, the final target film thickness flatness conditions) to ensure that the uniformity of the film thickness of the wafer W to be polished is maintained within a specified allowable range.

[0122] The first polishing condition can also be a polishing condition predetermined in order to achieve a flat final film thickness (controlling the pressure of each of the multiple pressure chambers 70, 71, 72, 73, and 83). The motion control unit 9 is configured to polish the wafer W while controlling the pressure of each of the multiple pressure chambers 70, 71, 72, 73, and 83 based on the first polishing condition.

[0123] Figure 5 This is a diagram showing multiple pressing regions of a wafer divided according to multiple pressure chambers. For example... Figure 5 As shown, the motion control unit 9 and multiple pressure chambers 70, 71, 72, and 73 are correspondingly divided into multiple pressing areas A1 to A4 on the wafer W. These pressing areas A1 to A4 are arranged concentrically with the center CPW of the wafer W. A groove Nt is formed on the outer edge of the wafer W.

[0124] In one embodiment, the first polishing condition can also be a polishing condition (CLC: closed-loop control) that controls the pressure of each pressure chamber 70-73 in real time, based on the film thickness measured by the film thickness sensor 40 during the polishing of the wafer W, so that the film thickness (average film thickness) of each region A1-A4 of the wafer W becomes the average film thickness of the entire wafer W. More specifically, the motion control unit 9 calculates the average film thickness value in each pressing region A1-A4 based on the film thickness of the wafer W measured based on the signal output from the film thickness sensor 40. Then, the motion control unit 9 controls the pressure in the pressure chambers 70-73 corresponding to the pressing regions A1-A4 by controlling each pressure adjuster R1-R4, so as to reduce the difference between the average film thickness value of each pressing region A1-A4 and the average film thickness value of the entire wafer W.

[0125] The motion control unit 9 can also control the pressure in the retaining ring pressure chamber 83 by controlling the pressure regulator R5, based on the same method as described above.

[0126] Figure 6 It is a diagram showing the grinding profile of a wafer when the wafer is ground under the first grinding conditions. Figure 6 In the figure, the horizontal axis represents the distance in the radial direction of wafer W, and the vertical axis represents the film thickness distribution of wafer W. Figure 6 The thick line in the figure represents the boundary line between the pressing area A4, which is located on the outermost periphery of the wafer W and the pressing area inside the pressing area A4, corresponding to the pressure chamber 73. Figure 6 The embodiment shown describes the film thickness distribution in the radial direction of the wafer W after grinding when the wafer W is ground for a predetermined time, but the grinding profile of the wafer W may also include the grinding rate distribution in the radial direction of the wafer W.

[0127] When wafer W is polished under the first polishing conditions, the uniformity of the film thickness of wafer W remains within a specified allowable range in other regions containing the central portion of wafer W (i.e., regions other than the outermost periphery). However, in a specific region containing the outermost periphery of wafer W, the residual film (polished film thickness) of wafer W exhibits significant fluctuations in the radial direction. Specifically, in this specific region containing the outermost periphery of wafer W, the difference in film thickness between thicker and thinner portions becomes larger. Due to the rebound effect of the polishing pad 2, the polishing profile of the outermost periphery of wafer W easily becomes asymmetrical abruptly, and it is difficult to obtain a flat film thickness distribution by simply adjusting the pressure chamber in this specific region containing the outermost periphery of wafer W. The degree of fluctuation in the polished film thickness (i.e., the so-called residual film range) in this specific region containing the outermost periphery of wafer W tends to increase with longer polishing times under the first polishing conditions.

[0128] Therefore, in this embodiment, the motion control unit 9 is configured to grind the wafer W based on a second grinding condition that reduces the degree of film thickness variation in the radial direction of the outermost periphery of the wafer W. In the embodiments shown below, as an example of a specific region of the wafer W, an implementation that reduces the degree of film thickness variation in the outermost periphery of the wafer W is described; however, the specific region of the wafer W is not limited to the outermost periphery. Even in regions other than the outermost periphery of the wafer W, film thickness variation can still occur.

[0129] Figure 7 This is a diagram representing the second grinding condition. Figure 7 In the figure, the horizontal axis represents the distance in the radial direction of wafer W, and the vertical axis represents the film thickness distribution of wafer W. Figure 7 In the embodiment shown, the grinding profile of wafer W is described as the film thickness distribution in the radial direction of the ground wafer W when the wafer W is ground for a specified time. However, the grinding profile of wafer W may also include the grinding rate distribution in the radial direction of wafer W.

[0130] The motion control unit 9 grinds a wafer that is the same as or has the same initial film thickness as the wafer W to be ground, based on the first grinding conditions. Then, the motion control unit 9 determines the second grinding conditions based on the first grinding profile (film thickness distribution or grinding rate distribution of the ground wafer W) obtained by grinding under the first grinding conditions. The second grinding conditions are grinding conditions that are predetermined (adjusted) to form a second grinding profile with a distribution opposite to the distribution of the first grinding profile (more specifically, the distribution of the pressing area on the wafer W corresponding to a specific pressure chamber).

[0131] In other words, the second polishing condition is a polishing condition that more aggressively polishes the outermost portion of the wafer W with a thick film thickness after polishing under the first polishing condition, while suppressing the polishing of the outermost portion of the wafer W with a thin film thickness. The distribution of the second polishing profile relative to the first polishing profile has a distribution with the signs of the numerical values ​​representing the film thickness or polishing rate of the wafer W reversed. Ideally, the curve representing the distribution of the second polishing profile is linearly symmetrical to the curve representing the distribution of the first polishing profile.

[0132] exist Figure 7 In the illustrated embodiment, in the film thickness distribution on a coordinate system determined by the distance from the radial direction of wafer W and the film thickness of wafer W corresponding to that distance, the curve representing the film thickness distribution of the outermost periphery of wafer W (the curve representing the distribution of the second polishing profile) takes the reference line as its center and is relative to the curve representing the film thickness distribution of the outermost periphery of wafer W polished under the first polishing conditions (reference). Figure 7 The dashed line (with a single dot) is symmetrical. Additionally, in Figure 7In the embodiment shown, the curve representing the distribution of the second grinding profile is depicted as an ideal curve.

[0133] The second polishing condition is determined by polishing a wafer with the same initial film thickness as or having the same initial film thickness as the wafer W to be polished. First, wafer W is polished under the first polishing condition to confirm the first polishing profile. Then, another wafer is further polished, and the second polishing condition is experimentally determined so that the polishing profile after polishing has a distribution opposite to that of the first polishing profile. Alternatively, in one embodiment, wafer W is first polished under the first polishing condition, and then polished under different polishing conditions. The second polishing condition, which serves as the switching condition for switching from the first polishing condition, is experimentally determined so that the polishing profile after polishing has a flat distribution. In one embodiment, the second polishing condition may also be selected from a database consisting of polishing conditions and polishing profiles pre-stored in the storage device 9a, and / or may be determined through polishing simulation.

[0134] The motion control unit 9 is configured to store second polishing conditions in its storage device 9a and polish the wafer W based on the second polishing conditions. More specifically, the motion control unit 9 polishes the wafer W while controlling the pressure of a specific pressure chamber among a plurality of pressure chambers 70, 71, 72, 73, and 83 at a predetermined fixed value based on the second polishing conditions. The second polishing conditions include polishing conditions for polishing the wafer W while controlling the pressure of a specific pressure chamber at a predetermined fixed value based on a second polishing profile.

[0135] The specific pressure chamber in this embodiment includes: an edge pressure chamber 73 pressing the outermost periphery of the wafer W; and an adjacent pressure chamber adjacent to the edge pressure chamber 73. The adjacent pressure chamber includes at least one of the intermediate pressure chamber 72 and the retaining ring pressure chamber 83. In this embodiment, the adjacent pressure chamber is both the intermediate pressure chamber 72 and the retaining ring pressure chamber 83. In one embodiment, the specific pressure chamber may also be only the edge pressure chamber 73.

[0136] The second grinding conditions include grinding conditions determined by adjusting the pressure of a specific pressure chamber. In one embodiment, the second grinding conditions may also include grinding conditions determined by adjusting the pressure of a pressure chamber other than the specific pressure chamber. For example, when the specific pressure chamber is the edge pressure chamber 73, the second grinding conditions include grinding conditions determined by adjusting the pressure of an adjacent pressure chamber adjacent to the edge pressure chamber 73.

[0137] In one embodiment, the second polishing condition may also include polishing conditions determined by adjusting the pressing pressure of the retaining ring 60, which is configured to surround the outermost periphery of the wafer W, relative to the polishing surface 2a. In this case, the motion control unit 9 controls the retaining ring pressing device 80, which applies the downward force of the polishing head 1 to the retaining ring 60, based on the second polishing condition.

[0138] In this embodiment, the motion control unit 9 controls the pressure of the edge pressure chamber 73 and the adjacent pressure chambers 72 and 83 based on the second grinding conditions, and at the same time controls the pressure of the other pressure chambers 70 and 71 other than these edge pressure chambers 73 and adjacent pressure chambers 72 and 83 based on the feedback of the first grinding conditions.

[0139] The first polishing condition is a polishing condition in which the pressure of each of the pressure chambers 70 and 71 is controlled by feedback based on the signal output from the film thickness sensor 40 in order to reduce the difference between the average film thickness value of the region corresponding to each of the other pressure chambers 70 and 71 and the average film thickness value of the entire wafer W.

[0140] Figure 8 It is a graph showing the polishing rate of wafers polished under the first polishing conditions and the second polishing conditions. Figure 8 In the figure, the horizontal axis represents the radial distance of wafer W, and the vertical axis represents the polishing rate of wafer W. Figure 8 The magnified view shows the polishing rate of the outer portion of wafer W. For example... Figure 8 As shown, the grinding rate of the pressing area A4 on the wafer W under the first grinding condition is reversed compared to the grinding rate of the pressing area A4 on the wafer W under the second grinding condition. Therefore, by combining the first grinding condition and the second grinding condition, the motion control unit 9 can improve the uniformity of the film thickness at the outermost periphery of the wafer W.

[0141] Figure 9 This diagram illustrates an example of the process of polishing a wafer. (Example) Figure 9 As shown in step S201, the motion control unit 9 grinds the wafer W under the first grinding conditions (first grinding process). Then, the motion control unit 9 determines whether the prescribed switching conditions are met (refer to step S202). If the switching conditions are not met (refer to "No" in step S202), step S201 continues. If the switching conditions are met (refer to "Yes" in step S202), the motion control unit 9 switches the grinding conditions from the first grinding conditions to the second grinding conditions (refer to step S203), and grinds the wafer W under the second grinding conditions (second grinding process).

[0142] If the fluctuation in the residual film thickness at the outermost periphery (i.e., a specific region) of wafer W is quite large (more specifically, the difference between the maximum and minimum film thickness values), even switching the polishing conditions from the first polishing condition to the second polishing condition may not eliminate the film thickness fluctuation at the outermost periphery of wafer W. Therefore, as the aforementioned switching condition, the operation control unit 9 may also switch the polishing conditions from the first polishing condition to the second polishing condition (first switching condition) when, during the polishing of wafer W under the first polishing condition, the difference between the maximum and minimum film thickness values ​​at the outermost periphery of wafer W (i.e., the so-called residual film range) significantly exceeds a predetermined threshold.

[0143] When the film thickness of the wafer W corresponding to a specific pressure chamber fluctuates greatly within a specific region, even adjusting the pressure of the specific pressure chamber may not eliminate the film thickness fluctuation. Therefore, in the above embodiment, when the residual film range of the wafer W under the first polishing condition significantly exceeds a predetermined threshold, the motion control unit 9 switches the polishing condition from the first polishing condition to the second polishing condition.

[0144] With a relatively short remaining polishing time, even if the polishing conditions are switched from the first polishing condition to the second polishing condition, it may still be impossible to eliminate the film thickness fluctuations in a specific area of ​​the wafer W. Therefore, as the aforementioned switching condition, the operation control unit 9 may also switch the polishing conditions from the first polishing condition to the second polishing condition (second switching condition) based on the time required to eliminate the difference between the maximum and minimum film thickness of the outermost periphery of the wafer W by polishing under the second polishing condition, and the remaining polishing time until the final target film thickness is reached.

[0145] The grinding rate when grinding wafer W under the second grinding condition is known in advance through the process of determining the second grinding condition. Therefore, when grinding wafer W under the second grinding condition, the motion control unit 9 can calculate the time required to reduce (eliminate) the residual film area of ​​wafer W during grinding under the first grinding condition. Therefore, in one embodiment, the motion control unit 9 can also switch the grinding condition from the first grinding condition to the second grinding condition when the required grinding time under the second grinding condition reaches or approaches the predetermined remaining time. The predetermined remaining time is, for example, the same as the time required for the film thickness of wafer W to reach the final target film thickness when grinding wafer W under the second grinding condition after the switching time.

[0146] More specifically, the motion control unit 9 calculates the time required (i.e., the required grinding time) and the remaining grinding time (i.e., the remaining time) for reducing the residual film area of ​​wafer W under the second grinding condition during grinding under the first grinding condition. The remaining grinding time is calculated based on the following formula: Remaining grinding time = (Current film thickness of wafer W - Target film thickness of wafer W) / Assumed grinding rate under the second grinding condition.

[0147] When the required grinding time is less than the remaining time (required grinding time << remaining time), the grinding time under the second grinding condition becomes longer, leading to a deterioration in the residual film profile of wafer W. When the required grinding time is the same as the remaining time (required grinding time = remaining time), the residual film area of ​​wafer W is eliminated, and the film thickness of wafer W reaches the target film thickness (ideal state). When the required grinding time is greater than the remaining time (required grinding time > remaining time), the film thickness of wafer W becomes the target film thickness before the residual film area is eliminated, and the residual film area cannot be eliminated. Continuing to grind under such circumstances leads to over-grinding. Therefore, it is desirable for the motion control unit 9 to switch the grinding condition from the first grinding condition to the second grinding condition when the required grinding time is the same as the remaining time.

[0148] According to the second switching condition, when the total amount of polishing varies, the range of residual film that can be polished under the first polishing condition can be changed. Therefore, for example, when the initial film thickness of wafer W varies, optimization can be performed accordingly. In addition, "the time required to reach the final target film thickness" refers to the time required to remove excess film when the final target film thickness is zero, i.e., in the case of polishing to remove the film on wafer W.

[0149] In one embodiment, the motion control unit 9 may switch the polishing conditions from the first polishing condition to the second polishing condition based on the first switching condition and the second switching condition. In one embodiment, the motion control unit 9 may also switch the polishing conditions from the first polishing condition to the second polishing condition when the average film thickness of the entire wafer W becomes a predetermined film thickness. In one embodiment, the motion control unit 9 may also switch the polishing conditions from the first polishing condition to the second polishing condition when the polishing time of the wafer W reaches a predetermined polishing time.

[0150] Motion Control Unit 9 Execution Figure 9 After step S203, the grinding of wafer W ends (refer to step S205) by receiving an endpoint detection signal from the film thickness sensor 40 indicating that the average film thickness of the entire wafer W has reached the target film thickness, or that the material formed on wafer W has reached the boundary with a different material (refer to "Yes" in step S204). If no endpoint detection signal is received (refer to "No" in step S204), the motion control unit 9 continues grinding wafer W under the second grinding conditions. The motion control unit 9 may also continue grinding wafer W under the second grinding conditions if the residual film range in a specific area is not below a predetermined value when the endpoint detection signal is received. Furthermore, the motion control unit 9 may also issue an alarm if the residual film range in a specific area is not below a predetermined value when the endpoint detection signal is received.

[0151] In the above embodiments, the grinding head 1 has multiple pressure chambers (air bladders), but the pressing assembly for pressing the wafer W is not limited to this. The technical concept of the present invention can be applied when multiple pressing assemblies that apply the same pressure to the wafer W are arranged in the radial direction of the wafer W. The pressing assembly may include, for example, a piezoelectric element.

[0152] Figure 10 This diagram illustrates an example of the process of correlating a reference spectrum with the corresponding film thickness. First, a reference wafer with the same or equivalent film thickness as wafer W is prepared. The reference wafer is then transferred to the film thickness measuring device 170 (reference...). Figure 1 The initial film thickness of the reference wafer is measured using a film thickness measuring device 170 (see step S301). The film thickness measuring device 170 is electrically connected to the motion control unit 9. Based on the film thickness (distribution) of the reference wafer measured by the film thickness measuring device 170, the motion control unit 9 determines a reference position for obtaining a reference spectrum over a wide range of film thicknesses (see step S302).

[0153] Thus, the motion control unit 9 obtains information from the film thickness measuring device 170 regarding a specific position on a portion of the circumference of the reference wafer. The film thickness measuring device 170 may also be disposed inside the polishing apparatus. In this case, the film thickness measuring device 170 forms part of the components of the polishing apparatus. In one embodiment, the film thickness measuring device 170 may also be disposed outside the polishing apparatus.

[0154] The reference wafer is polished to obtain reference spectra corresponding to various film thicknesses. Based on the measured film thickness of the reference wafer, the motion control unit 9 determines the maximum film thickness position (i.e., the thickest part of the reference wafer) and the minimum film thickness position (i.e., the thinnest part of the reference wafer) to obtain the maximum film thickness value, and designates one of these positions as the reference position. In one embodiment, the motion control unit 9 may also designate both the maximum and minimum film thickness positions as the reference positions.

[0155] In one embodiment, the motion control unit 9 may also determine the maximum film thickness value and the minimum film thickness value based on the measured film thickness of the reference wafer, calculate the difference between the average film thickness value of the entire reference wafer and the maximum film thickness value, and the difference between the average film thickness value of the entire reference wafer and the minimum film thickness value, and determine the position on the reference wafer with the film thickness value that has the largest difference as the reference position.

[0156] Next, the reference wafer is polished while the polishing slurry is supplied to the polishing head 1 (see step S303). During the polishing of the reference wafer, light is irradiated on the surface of the reference wafer to obtain the spectrum of the reflected light from the reference wafer (i.e., the reference spectrum) (see step S304).

[0157] The motion control unit 9 acquires reference spectra at each measurement point on the reference wafer every time the polishing stage 3 rotates once. During polishing, the motion control unit 9 controls at least one of the rotational speed of the polishing head 1 and the rotational speed of the polishing stage 3, such that the film thickness sensor 40 passes through the reference position on the reference wafer. Through such control, the film thickness sensor 40 detects the reflected light at the reference position, and the motion control unit 9 acquires a reference spectrum including the reference position.

[0158] The motion control unit 9 can obtain a reference spectrum over a wide range of film thickness values ​​by acquiring a reference spectrum that includes the reference position. Therefore, the motion control unit 9 can more reliably determine the reference spectrum that most closely resembles the measurement spectrum generated during grinding, resulting in the ability to measure (acquire) the film thickness of wafer W with all film thicknesses.

[0159] The reference spectrum is obtained every time the polishing table 3 rotates once. Therefore, multiple reference spectra are obtained during the polishing of the reference wafer. After the polishing of the reference wafer is completed, the reference wafer is transferred to the film thickness measuring device 170 again to measure the film thickness of the polished reference wafer (i.e., the final film thickness) (refer to step S305).

[0160] When the polishing rate of the reference wafer is constant, the film thickness decreases linearly along with the polishing time. The polishing rate can be calculated by dividing the difference between the initial film thickness and the final film thickness by the polishing time required to reach the final film thickness. As mentioned above, the reference spectra are obtained periodically every revolution of the polishing stage 3. Therefore, the polishing time for obtaining each reference spectrum can be calculated from the rotational speed of the polishing stage 3. Thus, the motion control unit 9 determines the film thickness corresponding to each reference spectrum (refer to step S306).

[0161] Each reference spectrum can be associated with (or combined with) the corresponding film thickness. Therefore, by determining the reference spectrum whose shape is closest to the measured spectrum during the grinding of the wafer W, the motion control unit 9 can determine the current film thickness of the wafer W from the film thickness associated with that reference spectrum.

[0162] Figure 11 This diagram illustrates an example of a process for polishing a wafer. To improve the uniformity of the film thickness on the wafer W, it is necessary to determine a specific location on the circumference of the wafer W. Therefore, as... Figure 11 As shown in step S401, the wafer W is transported to the film thickness measuring device 170, and the initial film thickness of the wafer W is measured by the film thickness measuring device 170.

[0163] Then, with Figure 10 Similarly, in step S302, the motion control unit 9 determines the specific position of the wafer W based on the film thickness of the wafer W measured by the film thickness measuring device 170 (see step S402).

[0164] The method for determining the specific position is the same as the method for determining the reference position. Based on the film thickness of the wafer W measured before polishing, the motion control unit 9 determines the maximum film thickness position (i.e., the part of the wafer W where the film thickness is thick) where the maximum film thickness value is obtained and the minimum film thickness position (i.e., the part of the wafer W where the film thickness is thin) where the minimum film thickness value is obtained, and determines at least one of the maximum film thickness position and the minimum film thickness position as the specific position.

[0165] In one embodiment, the motion control unit 9 may also determine the maximum and minimum film thickness values ​​based on the film thickness of the wafer W measured before polishing, and calculate the difference between the average film thickness of the entire wafer W and the maximum film thickness value, as well as the difference between the average film thickness of the entire wafer W and the minimum film thickness value, and determine the position on the wafer W with the largest difference as a specific position.

[0166] The motion control unit 9 obtains the film thickness distribution information of the wafer W measured by the film thickness measuring device 170, and determines a specific position of the wafer W. As one embodiment, when the film thickness measuring device 170 is disposed outside the polishing apparatus, the motion control unit 9 may also obtain position information of only the specified specific position from the film thickness distribution of the wafer W.

[0167] After determining the specific position of the wafer W, the motion control unit 9 begins grinding the wafer W (refer to step S403). During this grinding, light is irradiated onto the surface of the wafer W, and the motion control unit 9 obtains the spectrum of the reflected light from the wafer W (i.e., the measurement spectrum). The motion control unit 9 determines the reference spectrum whose shape is closest to the obtained measurement spectrum, and obtains the film thickness associated with the determined reference spectrum (refer to step S404).

[0168] The motion control unit 9 adjusts the pressing pressure of the wafer W relative to the polishing surface 2a based on the film thickness of the wafer W by controlling pressure adjusters R1, R2, R3, and R4. In this embodiment, the motion control unit 9 divides the area on the wafer W into multiple pressing areas A1, A2, A3, and A4 corresponding to multiple pressure chambers 70, 71, 72, and 73 (see reference). Figure 12 ).

[0169] Figure 12 This is a diagram showing that the chip is divided into multiple pressing areas. Figure 12 In this design, the area on the wafer W is divided into pressing areas A1 corresponding to pressure chamber 70; pressing areas A2 corresponding to pressure chamber 71; pressing areas A3 corresponding to pressure chamber 72; and pressing areas A4 corresponding to pressure chamber 73. Pressing area A1 has a circular shape, and pressing areas A2 to A4 each have an annular shape. These pressing areas A1 to A4 are arranged concentrically with the center CPW of the wafer W. The motion control unit 9 is configured to independently adjust the pressing pressure of the wafer W for each of the multiple pressing areas.

[0170] like Figure 12 As shown, a specific position IP exists in the pressing area A4 of chip W. Figure 12 In the illustrated embodiment, the specific location IP is a point on the wafer W, but the specific location IP can be multiple points existing in a narrow area on the wafer W or multiple points existing in a wide area on the wafer W. Therefore, the motion control unit 9 determines the control target area CA that includes the specific location IP. Furthermore, if an area of ​​a certain size including the specific location IP is used as the control target area, the film thickness uniformity adjustment described below can be performed stably. In this embodiment, the control target area CA is determined within a circumferential range (i.e., a range belonging to one of regions A1 to A4). In one embodiment, when the specific location IP is a point on the wafer W, the control target area CA can also be a point on the wafer W.

[0171] The motion control unit 9 determines the controllable film thickness value in the controllable region CA, and calculates the average film thickness value of the entire wafer W based on the film thickness of the wafer W measured by the film thickness sensor 40. The controllable film thickness value may also be equivalent to the maximum or minimum film thickness value determined based on the film thickness of the wafer W measured by the film thickness sensor 40, or it may be both the maximum and minimum film thickness values. In one embodiment, the controllable film thickness value may also be the average of multiple film thickness values ​​in the controllable region CA.

[0172] The motion control unit 9 controls at least one of the rotational speed of the polishing head 1 and the rotational speed of the polishing table 3 by having the film thickness sensor 40 pass through the control target area CA on the wafer W. To perform this control, the motion control unit 9 needs to determine the position of the control target area CA during the polishing of the wafer W.

[0173] As an example of a method for determining the position of the controlled object region CA, the motion control unit 9 determines, during the grinding of the wafer W, a reference position of the wafer W in the circumferential direction at an angle (i.e., wafer angle). Figure 12 The groove position Nt is determined, and the position of the control object area CA is used as the wafer angle.

[0174] Assuming that the wafer W has no circumferential deviation relative to the polishing head 1, the installation angle of the wafer W relative to the polishing head 1 at the start of polishing is kept constant. This is achieved by controlling the polishing head 1 via the rotary encoder 152 (see reference). Figure 13 The motion control unit 9 determines the groove position Nt and the position of the control target area CA based on the rotation angle of the grinding head 1. Even if the position of the groove position Nt is uncertain, the position of the control target area CA can still be determined from the rotation angle of the grinding head 1 because the positional relationship between the groove position Nt and the control target area CA is predetermined.

[0175] On the other hand, due to the frictional force acting between the wafer W and the polishing head 1, the wafer W may deviate from the polishing head 1 in the circumferential direction. At this time, since the relative angle between the groove position Nt and the polishing head 1 also deviates, the motion control unit 9 determines the groove position Nt of the wafer W in real time during the polishing of the wafer W, and determines the position of the control target area CA based on the groove position Nt.

[0176] Figure 13 This is a diagram showing a groove detection device. (For example...) Figure 13 As shown, the polishing apparatus may also include a groove detection device 151 for detecting the groove position Nt of the wafer W. The groove detection device 151 may also be composed of a sensor such as an eddy current sensor, an optical sensor, or an image sensor. Figure 13 In the illustrated embodiment, the groove detection device 151 is disposed to the side of the polishing table 3. The polishing head 1 is moved to a position where the periphery of the wafer W held on the polishing head 1 (more specifically, the groove position Nt) protrudes from the polishing pad 2, and the wafer W is rotated.

[0177] The groove detection device 151 detects the groove position Nt of the wafer W rotating while exposed from the polishing pad 2 and outputs a detection signal to the motion control unit 9. The rotary encoder 152 detects a signal corresponding to the rotation angle of the polishing head 1 and outputs the detection signal to the motion control unit 9. Thus, the motion control unit 9 can obtain the relationship between the groove position Nt and the rotation angle of the polishing head 1, and determine the relative angle between the groove position Nt and the polishing head 1 in real time. In one embodiment, the motion control unit 9 can also determine the groove position Nt based on the signal output from the film thickness sensor 40. In this case, the film thickness sensor 40 acts as the groove detection device.

[0178] Figure 14A and Figure 14B This is a diagram showing the movement path of a film thickness sensor across the surface of a wafer. Figure 14A and Figure 14B In the diagram, five dashed lines represent the moving path of the film thickness sensor 40. Figure 14A and Figure 14B In the embodiment shown, the film thickness sensor 40 passes through a specific position IP when the grinding table 3 rotates for the first time.

[0179] like Figure 14A and Figure 14B As shown, the motion control unit 9 controls the movement path of the film thickness sensor 40 by controlling at least one of the rotational speed of the polishing head 1 and the rotational speed of the polishing table 3. Therefore, the motion control unit 9 controls at least one of the rotational speed of the polishing head 1 and the rotational speed of the polishing table 3 based on the determined relative angle, so that the film thickness sensor 40 passes through a specific position IP on the surface of the wafer W.

[0180] For example, the motion control unit 9 can determine the movement path of the film thickness sensor 40 by determining the rotation speed ratio between the rotation speed of the grinding head 1 and the rotation speed of the grinding table 3. Figure 14A The rotational speed ratio in the illustrated embodiment is... Figure 14B The rotational speeds in the illustrated embodiments are different from each other. Therefore, when the relative angle between the groove position Nt and the polishing head 1 is changed, the motion control unit 9 determines the rotational speed ratio between the rotational speed of the polishing head 1 and the rotational speed of the polishing table 3 by means of the film thickness sensor 40 passing through a specific position IP on the surface of the wafer W.

[0181] Thus, the motion control unit 9 measures the film thickness of the control target area CA containing a specific position IP in the grinding process based on the signal output from the film thickness sensor 40, and controls the pressure in the pressure chambers 70 to 73 of the grinding head 1 corresponding to the control target area CA by controlling the pressure adjusters R1 to R4 based on the measured film thickness.

[0182] More specifically, such as Figure 11 As shown in step S405, the motion control unit 9 controls the pressure in the pressure chambers 70-73 of the polishing head 1 corresponding to a specific location IP (or the controlled object region CA) by reducing the difference between the film thickness value of the controlled object and the average film thickness value of the entire wafer W. Figure 12 In the illustrated embodiment, the control target area CA exists at a position on the wafer W corresponding to the pressing area A4, which corresponds to the pressure chamber 73. Therefore, the motion control unit 9 controls the pressure adjuster R4 to control the pressure in the pressure chamber 73.

[0183] The motion control unit 9 divides the multiple pressing areas A1 to A4 on the wafer W, which are divided according to the multiple pressure chambers 70 to 73, into a specific pressing area containing a specific position IP and other pressing areas other than the specific pressing area. In this embodiment, the specific pressing area corresponds to pressing area A4, and the other pressing areas correspond to pressing areas A1 to A3.

[0184] The motion control unit 9 calculates the average film thickness value in each of the other pressing areas A1 to A3 based on the film thickness of the wafer W measured by the film thickness sensor 40. Then, the motion control unit 9 controls the pressure in the pressure chambers 70 to 72 corresponding to the other pressing areas A1 to A3 by controlling the pressure regulators R1 to R3 in a way that reduces the difference between the average film thickness value of each of the other pressing areas A1 to A3 and the average film thickness value of the entire wafer W.

[0185] Figure 15A and Figure 15B This is a diagram used to illustrate the effect of the grinding process in this embodiment. Figure 15AThe outlines of the average film thickness of wafer W before and after polishing, as a comparative example, are shown. Figure 15B The outline of the average film thickness of wafer W before and after the polishing process of this embodiment is shown. Figure 15A and Figure 15B In the diagram, the horizontal axis represents the distance from the center CPW of wafer W, and the vertical axis represents the film thickness of wafer W. Figure 15A and Figure 15B In the diagram, the film thickness of wafer W is represented by a box plot as the film thickness at each measurement point in the pressing areas A1 to A4.

[0186] like Figure 15A As shown, in the film thickness of the wafer W before polishing, the minimum film thickness of the pressing area A3 is particularly small (or thinner) compared to the film thicknesses of the other pressing areas A1, A2, and A4. Furthermore, the maximum film thickness of the pressing area A4 is particularly large (or thicker) compared to the film thicknesses of the other pressing areas A1, A2, and A3. In the polishing process, which is a comparative example, the motion control unit 9 calculates the average film thickness of each pressing area A1 to A4 and the average film thickness of the entire wafer W based on the signal detected by the film thickness sensor 40. Therefore, because the motion control unit 9 calculates the average film thickness values ​​of each pressing area A3 and A4, the difference between the average film thickness values ​​of each pressing area A1 and A2 and the average film thickness values ​​of each pressing area A3 and A4 is sometimes small.

[0187] Even under these circumstances, the motion control unit 9 still controls the pressure of each of the pressure chambers 70 to 73 to polish the wafer W by reducing the difference between the average film thickness of each of the pressing areas A1 to A4 and the average film thickness of the entire wafer W. Therefore, sometimes the film thickness of the entire wafer W after polishing does not remain within the specified (desired) allowable range.

[0188] According to this embodiment, the motion control unit 9 individually controls the pressure of a specific pressing area with a pressure different from that of other pressing areas. More specifically, the motion control unit 9 controls the pressure in pressure chambers 72 and 73 by reducing the difference between the film thickness of the controlled object in each pressing area A3 and A4 and the average film thickness of the entire wafer W, and controls the pressure in each pressure chamber 70 and 71 by reducing the difference between the average film thickness of each other pressing area A1 and A2 and the average film thickness of the entire wafer W. Figure 15B As shown, the motion control unit 9 can also determine multiple specific pressing areas and individually control the pressure of the determined multiple specific pressing areas.

[0189] exist Figure 15BIn the illustrated embodiment, because the thickness of the film to be controlled in pressing region A3 is smaller than the average film thickness, the pressure in pressure chamber 72 is reduced compared to the pressure in the comparative example. As a result, the amount of grinding in pressing region A3 is generally smaller compared to the grinding amount in the comparative example. Because the thickness of the film to be controlled in pressing region A4 is larger than the average film thickness, the pressure in pressure chamber 73 is increased compared to the pressure in the comparative example. As a result, the amount of grinding in pressing region A4 is generally larger compared to the grinding amount in the comparative example. With this configuration, the grinding head 1 can maintain the thickness of the thickest and thinnest parts of the film in the entire wafer W within a desired allowable range (see reference). Figure 15B As a result, the uniformity of the film thickness across the entire wafer W can be improved.

[0190] In the above embodiments, the grinding head has multiple pressure chambers (air bladders); however, the technical concept of the present invention can be applied to any grinding head having concentrically arranged pressing components. The pressing force applied to the substrate by the concentrically arranged pressing components is controlled based on the thickness value of the control object film, which includes a control object region at a specific location. The pressing components may include, for example, piezoelectric elements.

[0191] In the above embodiments, the film thickness is estimated by determining a reference spectrum whose shape is closest to the measured spectrum, but other algorithms can also be used to estimate the film thickness.

[0192] In the above embodiments, the motion control unit 9 is configured to determine a specific position of the wafer W based on the film thickness of the wafer W measured by the film thickness measuring device 170, and control the pressure in the pressure chamber of the polishing head 1 corresponding to that specific position. In one embodiment, the motion control unit 9 may also be configured to control the pressure in the pressure chamber of the polishing head 1 without prior measurement of the film thickness of the wafer W. Hereinafter, the configuration of such a motion control unit 9 will be described with reference to the accompanying drawings.

[0193] Figure 16 This is a flowchart illustrating the pressure control within the pressure chamber implemented by the motion control unit. For example... Figure 16 As shown in step S501, the motion control unit 9 determines the maximum and minimum film thickness values ​​from the film thickness of the entire wafer W obtained by the film thickness sensor 40 during the grinding process. More specifically, the motion control unit 9 determines the maximum and minimum film thickness values ​​of the entire wafer W from the signal output by the film thickness sensor 40.

[0194] The motion control unit 9 divides the area on the wafer W into multiple pressing areas A1, A2, A3, and A4, corresponding to multiple pressure chambers 70, 71, 72, and 73. In other words, the motion control unit 9 divides the measurement data obtained by the film thickness sensor 40 into each pressing area A1, A2, A3, and A4 according to the trajectory of the film thickness sensor 40 as it passes through the surface of the wafer W. In addition to the maximum and minimum film thickness values, the motion control unit 9 also determines the average film thickness value of each of the multiple pressing areas A1, A2, A3, and A4. Furthermore, the motion control unit 9 also determines the average film thickness value of the entire wafer W.

[0195] like Figure 16 As shown in step S502, the motion control unit 9 determines whether the difference between the maximum and minimum film thickness values ​​(i.e., the film thickness range) in the entire wafer W is within a desired (specified) allowable range. When the film thickness range is within the allowable range (refer to "Yes" in step S502), the motion control unit 9 controls the pressure in each pressure chamber by controlling each pressure regulator in a way that reduces the difference between the average film thickness value of each pressing area and the average film thickness value of the entire wafer W (refer to step S503).

[0196] When the film thickness range exceeds the allowable range (refer to "No" in step S502), the motion control unit 9 determines at least one of the pressure chamber corresponding to the position of the wafer W where the maximum film thickness value is detected and the pressure chamber corresponding to the position of the wafer W where the minimum film thickness value is detected (refer to step S504).

[0197] When controlling the pressure of the pressure chamber associated with the maximum film thickness value, the motion control unit 9 controls the pressure of the pressure chamber so that the average film thickness value of the wafer W corresponding to the pressure chamber being targeted is lower than the average film thickness value of the entire wafer W (refer to step S505A). When controlling the pressure of the pressure chamber associated with the minimum film thickness value, the motion control unit 9 controls the pressure of the pressure chamber so that the average film thickness value of the wafer W corresponding to the pressure chamber being targeted is higher than the average film thickness value of the entire wafer W (refer to step S505B).

[0198] Specifically, when controlling the pressure of the pressure chamber associated with the maximum film thickness value, the motion control unit 9 calculates a target film thickness value that is reduced by a predetermined amount or a predetermined ratio relative to the average film thickness value of the entire wafer W, and adjusts the pressure of the target pressure chamber so that the average film thickness value of the pressing area to which the maximum film thickness value is measured is close to the target film thickness value. More specifically, when the average film thickness value of the pressing area to which the maximum film thickness value is measured exceeds the target film thickness value, the motion control unit 9 increases the pressure of the pressure chamber associated with the pressing area to which the maximum film thickness value is measured.

[0199] To narrow the film thickness range, the motion control unit 9 can control only the pressure of the pressure chamber associated with the maximum film thickness value, as described above; it can also control only the pressure of the pressure chamber associated with the minimum film thickness value, as described above; or it can control both the pressure of the pressure chamber associated with the maximum film thickness value and the pressure of the pressure chamber associated with the minimum film thickness value, as described above. Furthermore, regarding other pressure chambers, the motion control unit 9 controls them by reducing the difference between the average film thickness value of the corresponding pressing area and the average film thickness value of the entire wafer W.

[0200] With this configuration, when the film thickness range exceeds the allowable range, the grinding amount or grinding speed within a certain period corresponding to the pressing area of ​​the maximum film thickness value is greater than when the present invention is not applied, and the grinding amount or grinding speed within a certain period corresponding to the pressing area of ​​the minimum film thickness value is smaller than when the present invention is not applied. As a result, the grinding head 1 can keep the difference between the thickness of the thickest part and the thickness of the thinnest part of the film in the entire wafer W within a desired allowable range.

[0201] Figure 17 This diagram illustrates the effect of the grinding process in other embodiments. Figure 17 In the embodiment shown, during the polishing of wafer W, the maximum and minimum film thickness values ​​in the pressing regions A1 and A2 are within acceptable ranges. Therefore, the motion control unit 9 controls the pressure of each pressure chamber 70 and 71 corresponding to each pressing region A1 and A2 in a manner that reduces the difference between the average film thickness value of each pressing region A1 and A2 and the average film thickness value of the entire wafer W.

[0202] Because the minimum film thickness in the pressing area A3 exceeds the allowable range, the motion control unit 9 controls the pressure in the pressure chamber 72 to make the average film thickness in the pressing area A3 higher than the average film thickness of the entire wafer W. As a result, the amount of grinding in the pressing area A3 is reduced, and the grinding head 1 can keep the film thickness in the pressing area A3 within the allowable range.

[0203] Because the maximum film thickness in the pressing area A4 exceeds the allowable range, the motion control unit 9 controls the pressure in the pressure chamber 73 to make the average film thickness in the pressing area A4 lower than the average film thickness of the entire wafer W. As a result, the amount of polishing in the pressing area A4 increases, and the polishing head 1 can keep the film thickness in the pressing area A4 within the allowable range.

[0204] According to this embodiment, the motion control unit 9 does not measure the film thickness of the wafer W in advance, but can keep the difference in film thickness within the surface of the wafer W within an acceptable range based on the film thickness of the wafer W measured by the film thickness sensor 40 during the polishing of the wafer W.

[0205] Furthermore, even if the film thickness range exceeds the allowable range in the pressing area on the wafer W other than the pressing area on the wafer W corresponding to the maximum film thickness value and the pressing area on the wafer W corresponding to the minimum film thickness value, the motion control unit 9 can perform pressure control on that pressing area in the same way as described above.

[0206] In one embodiment, during the polishing of wafer W, the motion control unit 9 can also determine the maximum and minimum film thickness values ​​in wafer W based on the film thickness of wafer W obtained at certain time intervals. For example, the rotational speed ratio between polishing table 3 and polishing head 1 (rotational speed of polishing table 3 / rotational speed of polishing head 1) is 100 / 90min. －1 At that time, the grinding table 3 rotates ten more times relative to the grinding head 1 in 60 seconds.

[0207] With the aforementioned rotational speed ratio, since the polishing table 3 rotates ten times in 6 seconds and the polishing head 1 rotates nine times in 6 seconds, the relative positions of the polishing table 3 and the polishing head 1 return to their original positions once every 6 seconds. Because the film thickness sensor 40 is embedded in the polishing table 3, the number of times the film thickness sensor 40 passes through the surface of the wafer W depends on the rotation of the polishing table 3. Therefore, the movement path of the film thickness sensor 40 returns to its original position at a frequency of once every 6 seconds. Thus, the motion control unit 9 can determine the maximum and minimum film thickness values ​​based on the film thickness of the wafer W obtained from the time intervals during which the movement path of the film thickness sensor 40 returns to its original position.

[0208] In one embodiment, the motion control unit 9 may also determine the maximum and minimum film thickness values ​​of each of the multiple pressing areas A1, A2, A3, and A4 each time the grinding table 3 rotates once (i.e., the film thickness sensor 40 passes through one movement path each time) to control the pressure of each of the pressure chambers 70, 71, 72, and 73.

[0209] Each time the film thickness sensor 40 passes through a movement path, grinding is performed by controlling the pressure of each of the pressure chambers 70, 71, 72, and 73. Before the change in film thickness of the wafer W is reflected, the motion control unit 9 may start the next pressure adjustment.

[0210] Furthermore, if the pressure in the associated pressure chamber is adjusted frequently by calculating the difference between the maximum and minimum film thickness values ​​based on film thickness measurements taken over a certain period, the pressure responsiveness of the elastic membrane may become uncontrollable. Therefore, it is desirable for the motion control unit 9 to allow time for the pressure adjustment effect to occur and to check the next film thickness range at certain intervals. Additionally, even after pressure adjustment, the motion control unit 9 can re-measure the film thickness at the same measurement point to confirm the result of the pressure adjustment.

[0211] When the motion control unit 9 determines the maximum and minimum film thickness values, the polishing table 3 and polishing head 1 continue to rotate as usual, and the polishing of the wafer W continues as usual. Therefore, for example, if the time interval is determined to be 6 seconds, in the relationship between the film thickness of the wafer W obtained in the 1st second and the film thickness of the wafer W obtained in the 5th second, the motion control unit 9 will calculate that the film thickness obtained in the 5th second is thinner than the film thickness obtained in the 1st second, and will not be able to accurately assess the actual uniformity of the film thickness. Therefore, the motion control unit 9 is configured to correct the film thickness value of the wafer W at each acquisition timing based on the polishing speed of the wafer W.

[0212] Figure 18 This is a diagram illustrating the process of correcting the film thickness value through the motion control unit. (Example) Figure 18 As shown in step S601, the motion control unit 9 calculates the grinding speed of the wafer W during grinding based on the film thickness of the wafer W obtained by the film thickness sensor 40. Then, the motion control unit 9 calculates the amount of change in the film thickness of the wafer W between the acquisition time of the film thickness of the wafer W obtained by the film thickness sensor 40 at each measurement point of the wafer W and a predetermined reference time based on the grinding speed of the wafer W (refer to step S602).

[0213] The motion control unit 9 uses the change in film thickness as a correction value to correct the film thickness of wafer W obtained during the polishing process at certain time intervals (refer to step S603). For example, when the predetermined reference time is set to the beginning of the aforementioned time interval, i.e., 0 seconds, the film thickness of wafer W will gradually decrease from the reference time. Therefore, the motion control unit 9 adds the decrease in film thickness as a correction value to the film thickness of wafer W obtained during polishing to correct the film thickness of wafer W.

[0214] Conversely, when the predetermined reference time is set to the end of the aforementioned time interval (6 seconds in the above embodiment), since the film thickness of wafer W is measured to be thicker than the film thickness at the reference time, the motion control unit 9 subtracts the change in film thickness as a correction value from the film thickness of wafer W obtained during polishing to correct the film thickness of wafer W. The reference time can be arbitrarily determined as the start time or the middle time of the aforementioned time interval.

[0215] After step S603, the motion control unit 9 determines the maximum and minimum film thickness values ​​based on the corrected film thickness of the wafer W (refer to step S604). After step S604, the motion control unit 9 and... Figure 16 The pressure control process shown also controls the pressure in pressure chambers 70, 71, 72, and 73.

[0216] In the above embodiments, it is explained that the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are separate (or different) pressure chambers. However, sometimes the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber. In this case, the motion control unit 9 can also pre-determine, by setting the polishing scheme, whether to control the pressure of the target pressure chamber in such a way that the average film thickness value of the wafer W corresponding to the pressure chamber is lower than the average film thickness value of the entire wafer W, or to control the pressure of the target pressure chamber in such a way that the average film thickness value of the wafer W corresponding to the pressure chamber is higher than the average film thickness value of the entire wafer W.

[0217] In one embodiment, when the pressure chamber associated with the maximum film thickness value and the pressure chamber associated with the minimum film thickness value are the same pressure chamber, the motion control unit 9 can also calculate the first difference between the maximum film thickness value and the average film thickness value of the entire wafer W, and the second difference between the minimum film thickness value and the average film thickness value of the entire wafer W.

[0218] The motion control unit 9 compares the first difference with the second difference. If the first difference is greater than the second difference, the pressure of the target pressure chamber can be controlled such that the average film thickness of the wafer W corresponding to the pressure chamber associated with the maximum film thickness value is lower than the average film thickness value of the entire wafer W. If the second difference is greater than the first difference, the motion control unit 9 can also control the pressure of the target pressure chamber such that the average film thickness of the wafer W corresponding to the pressure chamber associated with the minimum film thickness value is higher than the average film thickness value of the entire wafer W.

[0219] In the above embodiment, the difference between the maximum film thickness value and the average film thickness value of the entire wafer W is set as the first difference, and the difference between the minimum film thickness value and the average film thickness value of the entire wafer W is set as the second difference. Alternatively, the difference between the maximum film thickness value and the average film thickness in the pressing area corresponding to the maximum film thickness value can be set as the first difference, and the difference between the minimum film thickness value and the average film thickness in the pressing area corresponding to the minimum film thickness value can be set as the second difference.

[0220] In the above embodiment, the motion control unit 9 determines whether the difference (film thickness range) between the maximum and minimum film thickness values ​​is within a desired (specified) allowable range. If it exceeds the allowable range, the pressure of the pressure chamber associated with the maximum film thickness value and / or the pressure chamber associated with the minimum film thickness value is adjusted. In one embodiment, the motion control unit 9 may also adjust the pressure of the pressure chamber associated with the maximum film thickness value and / or the pressure chamber associated with the minimum film thickness value without comparing the difference between the maximum and minimum film thickness values ​​and the allowable range. Therefore, since the pressure of the pressure chamber is controlled such that the average film thickness of the pressing area associated with the maximum film thickness value is lower than the average film thickness value of the entire wafer W, and the pressure of the pressure chamber is controlled such that the average film thickness of the pressing area associated with the minimum film thickness value is higher than the average film thickness value of the entire wafer W, the difference between the maximum and minimum film thickness values ​​can be reduced, thereby improving the uniformity of the film thickness of the wafer W.

[0221] The above embodiments are described with the aim of enabling those skilled in the art to practice the present invention. Various modifications of the above embodiments can naturally be made by those skilled in the art, and the technical concept of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is interpreted within the broadest scope of the technical concept defined by the claims.

[0222] [Industry availability]

[0223] This invention can be applied to grinding devices and grinding methods.

[0224] Symbol Explanation

[0225] 1: Grinding head

[0226] 2: Grinding pad

[0227] 2a: Grinding surface

[0228] 3: Grinding table

[0229] 5: Grinding fluid supply nozzle

[0230] 6: Motors

[0231] 7: Optical sensor head

[0232] 9: Motion Control Department

[0233] 9a: Storage device

[0234] 9b: Computing device

[0235] 10: Head shaft

[0236] 21: Head Body

[0237] 25: Rotary Joint

[0238] 40: Film thickness sensor

[0239] 44: Light source

[0240] 47: Spectrometer

[0241] 60: Retaining ring

[0242] 60a: Lower surface

[0243] 60b: Upper surface

[0244] 62: Drive ring

[0245] 65: Elastic membrane

[0246] 65a: Substrate pressing surface

[0247] 70: Central Pressure Chamber

[0248] 71: Intermediate pressure chamber

[0249] 72: Intermediate pressure chamber

[0250] 73: Edge pressure chamber

[0251] 80: Retaining ring pressing device

[0252] 81: Piston

[0253] 82: Rolling diaphragm

[0254] 83: Buffer ring pressure chamber

[0255] 151: Groove Detection Device

[0256] 152: Rotary Encoder

[0257] 170: Film thickness measuring instrument

Claims

1. A grinding apparatus, characterized in that, have: A grinding table that supports a grinding pad; A grinding head having a plurality of pressure chambers concentrically divided for pressing a substrate against the grinding surface of the grinding pad; Multiple pressure regulators are connected to the multiple pressure chambers; A film thickness sensor is embedded in the polishing stage and outputs a signal corresponding to the film thickness of the substrate. as well as The motion control unit individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure regulators. The motion control unit acquires information about a specific location that is part of the circumference of the substrate, and calculates the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate. The motion control unit controls the pressure in the pressure chamber of the polishing head corresponding to the specific location in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The motion control unit determines the specific position based on the film thickness of the substrate measured before grinding.

2. A grinding apparatus, characterized in that, have: A grinding table that supports a grinding pad; A grinding head having a plurality of pressure chambers concentrically divided for pressing a substrate against the grinding surface of the grinding pad; Multiple pressure regulators are connected to the multiple pressure chambers; A film thickness sensor is embedded in the polishing stage and outputs a signal corresponding to the film thickness of the substrate. as well as The motion control unit individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure regulators. The motion control unit acquires information about a specific location that is part of the circumference of the substrate, and calculates the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate. The motion control unit controls the pressure in the pressure chamber of the polishing head corresponding to the specific location in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The motion control unit determines the maximum film thickness position and the minimum film thickness position based on the film thickness of the substrate measured before polishing. The motion control unit determines at least one of the maximum film thickness position and the minimum film thickness position as the specific position.

3. A grinding apparatus, characterized in that, have: A grinding table that supports a grinding pad; A grinding head having a plurality of pressure chambers concentrically divided for pressing a substrate against the grinding surface of the grinding pad; Multiple pressure regulators are connected to the multiple pressure chambers; A film thickness sensor is embedded in the polishing stage and outputs a signal corresponding to the film thickness of the substrate. as well as The motion control unit individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure regulators. The motion control unit acquires information about a specific location that is part of the circumference of the substrate, and calculates the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate. The motion control unit controls the pressure in the pressure chamber of the polishing head corresponding to the specific location in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The motion control unit determines the maximum and minimum film thickness values ​​based on the film thickness of the substrate measured before polishing. The motion control unit calculates the difference between the average film thickness of the entire substrate and the maximum film thickness, and the difference between the average film thickness of the entire substrate and the minimum film thickness. The motion control unit determines the position on the substrate where the film thickness value with the largest difference is obtained as the specific position.

4. A grinding apparatus, characterized in that, have: A grinding table that supports a grinding pad; A grinding head having a plurality of pressure chambers concentrically divided for pressing a substrate against the grinding surface of the grinding pad; Multiple pressure regulators are connected to the multiple pressure chambers; A film thickness sensor is embedded in the polishing stage and outputs a signal corresponding to the film thickness of the substrate. as well as The motion control unit individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure regulators. The motion control unit acquires information about a specific location that is part of the circumference of the substrate, and calculates the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate. The motion control unit controls the pressure in the pressure chamber of the polishing head corresponding to the specific location in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The controlled film thickness value is equivalent to at least one of the maximum film thickness value and the minimum film thickness value determined based on the film thickness of the substrate measured before polishing.

5. A grinding apparatus, characterized in that, have: A grinding table that supports a grinding pad; A grinding head having a plurality of pressure chambers concentrically divided for pressing a substrate against the grinding surface of the grinding pad; Multiple pressure regulators are connected to the multiple pressure chambers; A film thickness sensor is embedded in the polishing stage and outputs a signal corresponding to the film thickness of the substrate. as well as The motion control unit individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure regulators. The motion control unit acquires information about a specific location that is part of the circumference of the substrate, and calculates the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate. The motion control unit controls the pressure in the pressure chamber of the polishing head corresponding to the specific location in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The film thickness value of the controlled object is the average of multiple film thickness values ​​within the controlled object region.

6. A grinding apparatus, characterized in that, have: A grinding table that supports a grinding pad; A grinding head having a plurality of pressure chambers concentrically divided for pressing a substrate against the grinding surface of the grinding pad; Multiple pressure regulators are connected to the multiple pressure chambers; A film thickness sensor is embedded in the polishing stage and outputs a signal corresponding to the film thickness of the substrate. as well as The motion control unit individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure regulators. The motion control unit acquires information about a specific location that is part of the circumference of the substrate, and calculates the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate. The motion control unit controls the pressure in the pressure chamber of the polishing head corresponding to the specific location in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The motion control unit measures the film thickness of the controlled target region, including the specific location, during the grinding process based on the signal output from the film thickness sensor. The motion control unit controls the pressure in the pressure chamber of the grinding head corresponding to the specific position based on the measured film thickness.

7. A grinding apparatus, characterized in that, have: A grinding table that supports a grinding pad; A grinding head having a plurality of pressure chambers concentrically divided for pressing a substrate against the grinding surface of the grinding pad; Multiple pressure regulators are connected to the multiple pressure chambers; A film thickness sensor is embedded in the polishing stage and outputs a signal corresponding to the film thickness of the substrate. as well as The motion control unit individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure regulators. The motion control unit acquires information about a specific location that is part of the circumference of the substrate, and calculates the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate. The motion control unit controls the pressure in the pressure chamber of the polishing head corresponding to the specific location in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The motion control unit divides the multiple pressing areas on the substrate, which are divided according to the multiple pressure chambers, into a specific pressing area that includes the controlled object area and other pressing areas besides the specific pressing area. The motion control unit calculates the average film thickness value of the other pressing areas based on the film thickness of the substrate. The motion control unit controls the pressure in the pressure chamber corresponding to the other pressing areas in a manner that reduces the difference between the average film thickness of the other pressing areas and the average film thickness of the entire substrate.

8. A grinding apparatus, characterized in that, have: A grinding table that supports a grinding pad; A grinding head having a plurality of pressure chambers concentrically divided for pressing a substrate against the grinding surface of the grinding pad; Multiple pressure regulators are connected to the multiple pressure chambers; A film thickness sensor is embedded in the polishing stage and outputs a signal corresponding to the film thickness of the substrate. as well as The motion control unit individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure regulators. The motion control unit acquires information about a specific location that is part of the circumference of the substrate, and calculates the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate. The motion control unit controls the pressure in the pressure chamber of the polishing head corresponding to the specific location in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The motion control unit obtains information about a reference position on the circumference of a reference substrate that is different from the substrate. During the grinding of the reference substrate, the motion control unit detects a physical quantity corresponding to the film thickness of the region on the substrate including the reference position using the film thickness sensor. The motion control unit acquires multiple data points corresponding to the film thickness of the reference substrate based on multiple signals received from the film thickness sensor. The motion control unit associates each of the plurality of data with the film thickness of the reference substrate at the time each of the plurality of data is acquired.

9. The grinding apparatus according to claim 8, characterized in that, The motion control unit determines the reference position based on the film thickness of the reference substrate measured before polishing.

10. A grinding apparatus, characterized in that, have: A grinding table that supports a grinding pad; A grinding head having a plurality of pressure chambers concentrically divided for pressing a substrate against the grinding surface of the grinding pad; Multiple pressure regulators are connected to the multiple pressure chambers; A film thickness sensor is embedded in the polishing stage and outputs a signal corresponding to the film thickness of the substrate. as well as The motion control unit individually controls the pressure of each of the plurality of pressure chambers via the plurality of pressure regulators. The motion control unit acquires information about a specific location that is part of the circumference of the substrate, and calculates the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate. The motion control unit controls the pressure in the pressure chamber of the polishing head corresponding to the specific location in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The motion control unit controls at least one of the rotational speed of the grinding head and the rotational speed of the grinding table by having the film thickness sensor pass through the controlled object area.

11. The grinding apparatus according to claim 10, characterized in that, The motion control unit determines the relative angle between the reference position and the grinding head based on the relationship between the reference position of the substrate in the circumferential direction and the rotation angle of the grinding head. The motion control unit controls at least one of the rotational speed of the grinding head and the rotational speed of the grinding table based on the determined relative angle.

12. A polishing method, wherein a substrate is pressed against the polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers concentrically divided, characterized in that, Information about a specific location that is part of the circumference of the substrate is obtained, and the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate are calculated. The pressure in the pressure chamber of the polishing head corresponding to the specific location is controlled in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The specific location is determined based on the film thickness of the substrate measured before polishing.

13. A polishing method, wherein a substrate is pressed against the polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers concentrically divided, characterized in that, Information about a specific location that is part of the circumference of the substrate is obtained, and the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate are calculated. The pressure in the pressure chamber of the polishing head corresponding to the specific location is controlled in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. Based on the film thickness of the substrate measured before polishing, the maximum film thickness location and the minimum film thickness location are determined. The specific location is determined by at least one of the maximum film thickness location and the minimum film thickness location.

14. A polishing method, wherein a substrate is pressed against the polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers concentrically divided, characterized in that, Information about a specific location that is part of the circumference of the substrate is obtained, and the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate are calculated. The pressure in the pressure chamber of the polishing head corresponding to the specific location is controlled in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. Based on the film thickness of the substrate measured before polishing, the maximum and minimum film thickness values ​​are determined. Calculate the difference between the average film thickness of the entire substrate and the maximum film thickness, and the difference between the average film thickness of the entire substrate and the minimum film thickness. The location on the substrate where the film thickness value with the largest difference is obtained is determined as the specific location.

15. A polishing method, wherein a substrate is pressed against the polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers concentrically divided, characterized in that, Information about a specific location that is part of the circumference of the substrate is obtained, and the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate are calculated. The pressure in the pressure chamber of the polishing head corresponding to the specific location is controlled in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The controlled film thickness value is equivalent to at least one of the maximum film thickness value and the minimum film thickness value determined based on the film thickness of the substrate measured before polishing.

16. A polishing method, wherein a substrate is pressed against the polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers concentrically divided, characterized in that, Information about a specific location that is part of the circumference of the substrate is obtained, and the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate are calculated. The pressure in the pressure chamber of the polishing head corresponding to the specific location is controlled in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The film thickness value of the controlled object is the average of multiple film thickness values ​​within the controlled object region.

17. A polishing method, wherein a substrate is pressed against the polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers concentrically divided, characterized in that, Information about a specific location that is part of the circumference of the substrate is obtained, and the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate are calculated. The pressure in the pressure chamber of the polishing head corresponding to the specific location is controlled in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. Based on the output signal of the film thickness sensor, the film thickness of the controlled object region including the specific location in the grinding process is measured. The pressure in the pressure chamber of the grinding head corresponding to the specific location is controlled based on the measured film thickness.

18. A polishing method, wherein a substrate is pressed against the polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers concentrically divided, characterized in that, Information about a specific location that is part of the circumference of the substrate is obtained, and the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate are calculated. The pressure in the pressure chamber of the polishing head corresponding to the specific location is controlled in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. The multiple pressing areas on the substrate, divided according to the multiple pressure chambers, are further divided into a specific pressing area containing the controlled object area and other pressing areas besides the specific pressing area. The average film thickness of the other pressing areas is calculated based on the film thickness of the substrate. The pressure in the pressure chamber corresponding to the other pressing areas is controlled in a way that reduces the difference between the average film thickness of the other pressing areas and the average film thickness of the entire substrate.

19. A polishing method, wherein a substrate is pressed against the polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers concentrically divided, characterized in that, Information about a specific location that is part of the circumference of the substrate is obtained, and the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate are calculated. The pressure in the pressure chamber of the polishing head corresponding to the specific location is controlled in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. Obtain information about a reference position on the circumference of a reference substrate that is different from the said substrate. During the polishing of the reference substrate, a physical quantity corresponding to the film thickness of the region on the substrate including the reference position is detected by a film thickness sensor. Based on multiple signals received from the film thickness sensor, multiple data points corresponding to the film thickness of the reference substrate are obtained. Each of the plurality of data is associated with the film thickness of the reference substrate at the time each of the plurality of data is obtained.

20. The grinding method according to claim 19, characterized in that, The reference position is determined based on the film thickness of the reference substrate measured before polishing.

21. A polishing method, wherein a substrate is pressed against the polishing surface of a polishing pad by a polishing head having a plurality of pressure chambers concentrically divided, characterized in that, Information about a specific location that is part of the circumference of the substrate is obtained, and the control target film thickness value of the control target area including the specific location and the average film thickness value of the entire substrate are calculated. The pressure in the pressure chamber of the polishing head corresponding to the specific location is controlled in a manner that reduces the difference between the film thickness of the controlled object and the average film thickness of the entire substrate. By rotating the grinding table that supports the grinding pad, at least one of the rotational speed of the grinding head and the rotational speed of the grinding table is controlled in such a way that the film thickness sensor passes through the controlled object area.

22. The grinding method according to claim 21, characterized in that, Based on the relationship between the reference position of the substrate in the circumferential direction and the rotation angle of the grinding head, the relative angle between the reference position and the grinding head is determined. The rotational speed of the grinding head and the rotational speed of the grinding table are controlled based on the determined relative angle.

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