Polishing apparatus and method for creating film thickness profile in polishing apparatus

Abstract

A polishing apparatus includes a polishing table which is provided with a sensor, a polishing head which is constructed to allow a substrate to be attached to a surface facing the polishing table, and a controller. The sensor is constructed to output, when the sensor passes a path on the substrate, time series data that comprises a series of pieces of measurement data relating to film thicknesses at multiple measurement points on the path: and the controller is constructed to obtain the time series data from the sensor; apply interpolation using a first interpolation pitch to the measurement data in a first data range in the time series data; apply interpolation using a second interpolation pitch, that is different from the first interpolation pitch, to the measurement data in a second data range in the time series data; and create a film thickness profile corresponding to the path.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims priority from Japanese Patent Application No. 2025-048164, filed on Mar. 24, 2025, with the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.TECHNICAL FIELD

[0002] The present invention relates to a polishing apparatus and a method for creating a film thickness profile in a polishing apparatus.BACKGROUND

[0003] There is a CMP (Chemical Mechanical Polishing) apparatus in apparatuses for manufacturing semiconductor devices. A representative CMP apparatus comprises a polishing table to which a polishing pad is attached, and a polishing head to which a substrate is attached. In the representative CMP apparatus, a substrate is polished by supplying a polishing liquid to the polishing pad, and rotating, in the state that the polishing pad and the substrate are in contact with each other, at least one of the polishing table and the polishing head.

[0004] During the time when a substrate is being polished, a sensor such as an eddy current sensor installed in a polishing table, for example, is used for measuring thickness of a film which is an object of polishing. The sensor moves along a path on a surface of a substrate as a polishing table rotates, and measures film thickness at each of points on the path. A film thickness profile that represents film thickness distribution on the substrate can be created based on data of film thickness measurement at the respective points on the path (for example, refer to Japanese Patent Laid-Open Publication No. 2022-510757).SUMMARY OF INVENTION

[0005] A sensor obtains film thickness measurement data at discrete measurement points on a substrate. For improving definition of a film thickness profile, an interpolation process may be applied to the measurement data obtained at the discrete measurement points. However, the interpolation process requires a certain calculation load. In other words, improvement of definition of a film thickness profile and the quantity of the calculation load are in a trade-off relationship.

[0006] According to an embodiment, a polishing apparatus is provided: wherein the polishing apparatus comprises a polishing table which is provided with a sensor and constructed to be able to rotate; a polishing head which is arranged to face the polishing table, constructed to be able to rotate, and constructed to allow a substrate to be attached to a surface facing the polishing table; and a controller: wherein the sensor is constructed to output, when the sensor passes a path on the substrate, time series data that comprises a series of pieces of measurement data relating to film thicknesses at multiple measurement points on the path: and the controller is constructed to obtain the time series data from the sensor; apply interpolation using a first interpolation pitch to the measurement data in a first data range in the time series data; apply interpolation using a second interpolation pitch, that is different from the first interpolation pitch, to the measurement data in a second data range in the time series data; and create a film thickness profile corresponding to the path, based on the interpolated measurement data in the first data range and the second data range.

[0007] In the above embodiment, each of the interpolation using the first interpolation pitch and the interpolation using the second interpolation pitch may include a process for creating, based on the measurement data obtained at the multiple measurement points on the path, interpolation data for one or multiple interpolation points between the multiple measurement points on the path.

[0008] In the above embodiment, each of the first interpolation pitch and the second interpolation pitch may represent a distance between the interpolation points or a distance between the interpolation point and the measurement point.

[0009] In the above embodiments, the first data range may correspond to a part near an edge of the substrate, the second data range may correspond to a part on an inner side of the part near the edge of the substrate, and the first interpolation pitch may be narrower than the second interpolation pitch.

[0010] In the above embodiment, the controller may further be constructed to accept a user input for designating the first data range and the second data range.

[0011] In the above embodiments, the controller may further be constructed to judge that successive pieces of measurement data corresponding to adjacent measurement points on the path, in the time series data, belong to the first data range, if a difference between the successive pieces of measurement data is larger than a predetermined value, and judge that successive pieces of measurement data corresponding to adjacent measurement points on the path, in the time series data, belong to the second data range, if a difference between the successive pieces of measurement data is smaller than a predetermined value; wherein the first interpolation pitch is narrower than the second interpolation pitch.

[0012] In the above embodiments, the controller may further be constructed to obtain a reference profile with respect to film thickness relating to the path on the substrate, judge that pieces of measurement data in the time series data belong to the first data range, if each of deviations of the pieces of measurement data from related parts in the reference profile is larger than a predetermined value, and judge that pieces of measurement data in the time series data belong to the second data range, if each of deviations of the pieces of measurement data from related parts in the reference profile is smaller than the predetermined value; wherein the first interpolation pitch is narrower than the second interpolation pitch.

[0013] In the above embodiment, the reference profile may be created in advance by using measurement data obtained from the sensor when multiple substrates were polished.

[0014] In the above embodiments, the controller may further be constructed to obtain data representing a speed of rotation of the polishing table or a speed of rotation of the polishing head, judge that pieces of measurement data in the time series data belong to the first data range, if the speed of rotation when the pieces of measurement data are obtained is slower than a predetermined speed of rotation, and judge that pieces of measurement data in the time series data belong to the second data range, if the speed of rotation when the pieces of measurement data are obtained is faster than the predetermined speed of rotation; wherein the first interpolation pitch is narrower than the second interpolation pitch.

[0015] In the above embodiment, the data representing the speed of rotation may be obtained from a rotation speed sensor, or may be designated by a user input.

[0016] In the above embodiments, the controller may further be constructed to display the created film thickness profile on a display.

[0017] According to a further embodiment, a method for creating a film thickness profile in a polishing apparatus is provided: wherein the polishing apparatus comprises a polishing table which is provided with a sensor and constructed to be able to rotate, and a polishing head which is arranged to face the polishing table, constructed to be able to rotate, and constructed to allow a substrate to be attached to a surface facing the polishing table; and the method comprises steps for outputting, by the sensor when the sensor passes a path on the substrate, time series data that comprises a series of pieces of measurement data relating to film thicknesses at multiple measurement points on the path, obtaining the time series data from the sensor, applying interpolation using a first interpolation pitch to the measurement data in a first data range in the time series data, applying interpolation using a second interpolation pitch, that is different from the first interpolation pitch, to the measurement data in a second data range in the time series data, and creating a film thickness profile corresponding to the path, based on the interpolated measurement data in the first data range and the second data range.BRIEF DESCRIPTION OF DRAWINGS

[0018] FIG. 1 is a schematic drawing which shows a construction of a polishing apparatus according to an embodiment of the present invention.

[0019] FIG. 2 is a schematic drawing which shows an example path of a sensor.

[0020] FIG. 3 is a figure which shows a construction of a controller in a film thickness measuring apparatus, in a polishing apparatus according to an embodiment of the present invention.

[0021] FIG. 4 is a flow chart which shows operation of a polishing apparatus according to an embodiment of the present invention.

[0022] FIG. 5 is a schematic drawing which shows a part near an edge of a substrate.

[0023] FIG. 6 is a schematic drawing which is based on example measurement data and is to be used for explaining an interpolation process.

[0024] FIG. 7 is an additional explanatory drawing relating to the interpolation process.

[0025] FIG. 8 is a flow chart which shows operation of a polishing apparatus according to a different embodiment of the present invention.

[0026] FIG. 9 is a flow chart which shows operation of a polishing apparatus according to the other different embodiment of the present invention.

[0027] FIG. 10 is a schematic drawing which shows examples of a reference profile and measurement data.

[0028] FIG. 11 is a flow chart which shows operation of a polishing apparatus according to a further different embodiment of the present invention.DESCRIPTION OF EMBODIMENTS

[0029] In the following description, embodiments of the present invention will be explained with reference to the figures. In the figures which will be explained in the following description, a reference symbol assigned to one component is also assigned to the other component if the other component is the same as or corresponds to the one component, and overlapping explanation of these components will be omitted.

[0030] FIG. 1 is a schematic drawing which shows a construction of a polishing apparatus 10 according to an embodiment of the present invention. As shown in the figure, the polishing apparatus 10 comprises a polishing table 30 for holding a polishing pad 31, and a top ring 40 (a polishing head) for holding a substrate (a wafer) W, which is an object of polishing, in such a manner that the substrate faces the polishing pad 31, and pushing the substrate to a polishing surface of the polishing pad 31.

[0031] The polishing table 30 is connected, via a table shaft 32, to a table driving motor (which is not shown in the figure) positioned below the table shaft 32. The table driving motor is driven to rotate, and, accordingly, the polishing table 30 is able to rotate about an axis of the table shaft 32. The polishing pad 31 is attached to a top surface of the polishing table 30. A surface 311 of the polishing pad 31 comprises a polishing surface for polishing the wafer W. A polishing liquid supplying nozzle, which is not shown in the figure, is arranged in a position above the polishing table 30, and a polishing liquid is supplied from the polishing liquid supplying nozzle to the polishing pad 31 on the polishing table 30.

[0032] The top ring 40 is supported by an arm 50 via a top ring shaft 42. By using an up-and-down motion mechanism which is not shown in the figure, the top ring shaft 42 is able to move upward and downward in relation to the arm 50. Positioning of the top ring 40 relative to the arm 50 may be performed by moving the top ring 40 upward / downward by making the top ring shaft 40 move upward and downward. The top ring 40 is constructed to hold, on its bottom surface, the wafer W. Specifically, as shown in FIG. 1, the top ring 40 comprises a retainer ring 41A which holds an outer peripheral edge of the wafer W to prevent the wafer W from jumping out of the top ring 40, and a top-ring main body 41B which pushes the wafer W to the polishing surface 311.

[0033] A top ring driving motor 43 is fixed to the arm 50 which supports the top ring 40. Further, as shown in FIG. 1, the top ring shaft 42 is connected to a rotary cylinder 61; and a timing pulley 62 installed on an outer periphery of the rotary cylinder 61 is connected, via a timing belt 63, to a timing pulley 64 installed on the top ring driving motor 43. According to the above construction, as the top ring driving motor 43 rotates, the rotary cylinder 61 and the top ring shaft 42 integrally rotates via the timing pulley 64, the timing belt 63, and the timing pulley 62; and the top ring 40 rotates about the axis of the top ring shaft 42.

[0034] The arm 50 is connected to an arm driving motor 53 which is fixed to an arm shaft 52. The arm 50 and the top ring 40 supported by the arm 50 are able to rotate about the axis of the arm shaft 52 by driving the arm driving motor 53.

[0035] When the polishing apparatus 10 performs action, first, the top ring 40 receives, at a predetermined receiving position, the wafer W conveyed by a conveyance mechanism which is not shown in the figure, and holds the wafer W. The top ring 40, which has received the wafer W at the receiving position, is moved from the receiving position to a position above the polishing table 30 by rotational movement of the arm 50. Next, the top ring shaft 42 and the top ring 40 are moved downward, and, accordingly, the wafer W is pushed to the polishing surface 311 of the polishing pad 31. Thereafter, the table driving motor and the top ring driving motor 43 are driven to rotate them to thereby rotate the polishing table 30 and the top ring 40, respectively; and, at the same time, a polishing liquid is supplied on the polishing pad 31 from the polishing liquid supplying nozzle installed in a position above the polishing table 30. According to the above construction, the wafer W is brought into contact, in a sliding contact manner, with the polishing surface 311 of the polishing pad 31, and the surface of the wafer W is polished accordingly. During polishing of the wafer W, polishing may be performed in such a manner that the top ring 40 is moved in a swinging manner relative to the polishing pad 31 (i.e., it is moved back and forth on the polishing pad 31) by making the arm 50 periodically swing to the left and to the right by the arm driving motor 53.

[0036] In an embodiment of the present invention, the polishing apparatus 10 further comprises a film thickness measuring apparatus 100 for measuring thickness of a film on the substrate W when it is being polished by the polishing apparatus 10. The film thickness measuring apparatus 100 comprises a sensor 110 installed in the polishing apparatus 10, and a controller 120 for processing signals from the sensor 110 to create a film thickness profile. The sensor 110 may be a sensor of any type, such as an eddy current sensor, an optical sensor, an acoustic sensor, an ultrasonic sensor, or the like which can measure thickness of a film on the substrate W. The sensor 110 may be installed in a part that is in the inside of the polishing table 30 and is near the substrate W, as shown in FIG. 1, for example. During the time when the substrate W is being polished by operating the polishing table 30 and the top ring 40 to rotate them, the sensor 110 moves, on the substrate W, along an arc-shaped path that is determined according rotation of the polishing table 30 and the top ring 40.

[0037] FIG. 2 is a schematic drawing which shows an example path of the sensor 110. During each single rotation of the polishing table 30, the sensor 110 crosses the surface of the substrate W along an arc-shaped path 202 having a predetermined curvature, and outputs pieces of measurement data relating to film thickness at respective measurement points 204 that are arranged at predetermined intervals on the path 202. The sensor 110 is connected to the controller 120 to electrically communicate with it; and time series data, that is outputted from the sensor 110 and comprises a series of pieces of measurement data corresponding to the multiple measurement points 204 on the path 202, is supplied to the controller 120. The controller 120 is able to create, based on the series of pieces of measurement data from the sensor 110, a film thickness profile of a film on the substrate W which is being polished by the polishing apparatus 10.

[0038] FIG. 3 is a figure which shows a construction of the controller 120 in the film thickness measuring apparatus 100 in the above-explained polishing apparatus 10 according to an embodiment of the present invention. The controller 120 comprises a processor 122 and a memory 124. The memory 124 stores a program 126 (computer executable instructions) for realizing a method according to an embodiment of the present invention. The processor 122 reads the program 126 out of the memory 124 and executes it. As a result, the method according to the embodiment of the present invention is realized.

[0039] FIG. 4 is a flow chart which shows operation of the polishing apparatus 10 according to an embodiment of the present invention. A process in each of steps in the flow chart in FIG. 4 is performed by the processor 122 in the controller 120 in the film thickness measuring apparatus 100. The method according to the embodiment in FIG. 4 starts from step 402 during an operation preparing stage of the polishing apparatus 10.

[0040] In step 402, the processor 122 receives a user input that designates an interpolation condition(s) for performing interpolation of the measurement data outputted from the sensor 110. The interpolation condition includes information relating to an interpolation pitch that is used when performing interpolation of the measurement data outputted from the sensor 110. Specifically, with respect to a time series data comprising a series of pieces of measurement data obtained from the sensor 110, the interpolation condition represents a range in the pieces of the measurement data to that an interpolation process using a first interpolation pitch should be applied, and a range in the pieces of the measurement data to that an interpolation process using a second interpolation pitch should be applied. For example, a user input may be that for designating a condition such that pieces of measurement data corresponding to a belt-shaped area 504 that is close to an edge 502 of the substrate W and has a width d as shown in FIG. 5 is to be subjected to an interpolation process using a first interpolation pitch, and pieces of measurement data corresponding to a center area 506 positioned on an inner side of the area 504 is to be subjected to an interpolation process using a second interpolation pitch.

[0041] Next, in step 404, the polishing apparatus 10 starts polishing of the substrate W. In step 406 that follows the above step, as the sensor 110 moves along a path (for example, the path 202 in FIG. 2) on the substrate W, the processor 122 sequentially obtains, from the sensor 110, respective pieces of measurement data obtained at respective measurement points (for example, the respective points 204 in FIG. 2) on the path. Further, in step 408, the processor 122 calculates, from each of the obtained pieces of measurement data, film thickness at each of the measurement points.

[0042] Next, in step 410, based on the interpolation condition designated in step 402, the processor 122 makes a judgment as to whether each of measurement points relating to the series of pieces of measurement data obtained by the sensor 110 is in a position in the part near the edge of the substrate W. With respect to a range of pieces of measurement data, in the whole range of pieces of measurement data, that relates to measurement points positioned in the part near the edge of the substrate W (for example, the belt-shaped area 514 in FIG. 5), the processor 122 applies thereto the interpolation process using the first interpolation pitch in step 412. On the other hand, with respect to a range of pieces of measurement data, in the whole range of pieces of measurement data, that relates to measurement points positioned in the part on the inner side of the above part near the edge of the substrate W (for example, the area 506 in FIG. 5), the processor 122 applies thereto the interpolation process using the second interpolation pitch in step 414. In the present case, the first interpolation pitch is that narrower than the second interpolation pitch.

[0043] FIG. 6 is a schematic drawing which is based on example measurement data and is to be used for explaining the interpolation processes performed in steps 412 and 414. A horizontal axis of a graph in FIG. 6 represents positions on the substrate W along a path, and a vertical axis represents film thickness values. In the graph in FIG. 6, a position X0 corresponds to an edge of the substrate W (the edge 502 in FIG. 5), and a range 602 between the position X0 and a position X1, that is positioned on an inner side of the substrate W and separate from the position X0 by a distance d, corresponds to the part near the edge of the substrate W (the belt-shaped area 504 in FIG. 5). As shown in FIG. 6, the processor 122 applies an interpolation process using a first interpolation pitch p1 to the measurement data in the range 602 that corresponds to the part near the edge of the substrate W. Further, the processor 122 applies an interpolation process using a second interpolation pitch p2 to the measurement data in the range 604 that corresponds to the part positioned on the inner side of the part near the edge of the substrate W (the area 506 in FIG. 5). In this regard, an interpolation pitch refers to a distance between interpolation points shown by multiple circles in FIG. 6 or a distance between an interpolation point and a measurement point, and an interpolation point(s) refers to a point(s) for interpolation between the measurement points. For example, the first interpolation pitch p1 may be 0.1 mm and the second interpolation pitch p2 may be 1 mm; and, in this regard, the above values are mere examples so that the values are not limited to the above values.

[0044] FIG. 7 is an additional explanatory drawing relating to the interpolation process. As explained above, the processor 122 obtains a series of pieces of measurement data MD1, MD2, MD3, and so on from the sensor 110. Measurement points mx1, mx2, mx3, and so on corresponding to the pieces of measurement data correspond to the measurement points 204 on the sensor path 202 shown in FIG. 2, respectively. The processor 122 performs the interpolation process by creating, based on the pieces of measurement data MD1, MD2, MD3, and so on, pieces of interpolation data ID1, ID2, ID3, and so on as those corresponding to multiple interpolation points ix1, ix2, ix3, and so on that are set in positions whereat a distance between adjacent measurement points in measurement points mx1, mx2, mx3, and so on is divided into distances, each distance corresponding to a predetermined interpolation pitch (the first interpolation pitch p1 or the second interpolation pitch p2). In this regard, any interpolation algorithm such as linear interpolation, spline interpolation, or the like, may be applicable to the method for creating interpolation data from measurement data.

[0045] The flow chart in FIG. 4 will be referred to again herein; and, next, in step 416, the processor 122 creates, by using the result of interpolation, a film thickness profile of the film on the substrate W along the path corresponding to the measurement data. FIG. 6 shows an example film thickness profile PF created in the manner explained above. The created film thickness profile (for example, visual representation using a graph such as the film thickness profile PF shown in FIG. 6) is displayed on a display device which is associated with the polishing device 10 or is arranged in a remote position, for allowing an operator of the polishing apparatus 10 to check the state of polishing of the substrate W, the state of progress in polishing, and so on. Next, in step 418, based on the film thickness profile, the processor 122 makes a judgment as to whether polishing of the substrate W has been completed. For example, a decision to terminate the polishing process may be made in response to a state that the film thickness profile has become that having a desired degree of flatness, and / or a state that the film thickness has become a desired thickness. If a predetermined termination condition is satisfied, the polishing apparatus 10 terminates, in step 420, the polishing process applied to the substrate W.

[0046] As explained above, according to the present embodiment, it becomes possible to draw an accurate film thickness profile with respect to the part near the edge of the substrate W, where change in measurement data is large, by applying thereto an interpolation process using a narrow interpolation pitch, and reduce a calculation load relating to interpolation with respect to the part on the inner side of the substrate W, where change in measurement data is small, by applying thereto an interpolation process using a wide interpolation pitch.

[0047] FIG. 8 is a flow chart which shows operation of the polishing apparatus 10 according to a different embodiment of the present invention. A process in each of steps in the flow chart in FIG. 8 is performed by the processor 122 in the controller 120 in the film thickness measuring apparatus 100. At the time when operation of the polishing apparatus 10 starts, the method according to the embodiment in FIG. 8 starts from step 804. In this regard, the processes performed in steps 804, 806, 808, 816, 818, and 820 in the flow chart in FIG. 8 are similar to those performed in steps 404, 406, 408, 416, 418, and 420 in the above-explained flow chart in FIG. 4, respectively; and explanation thereof may be omitted accordingly.

[0048] In step 810, based on the pieces of measurement data obtained by the sensor 110, the processor 122 makes a judgment as to whether a difference between pieces of measurement data corresponding to measurement points in each of pairs of adjacent measurement points on the path is larger than a predetermined threshold value. As can be seen from the above-explained FIG. 6, the difference between pieces of measurement data corresponding to the adjacent measurement points on the path is large in the case that the measurement points are those in the part near the edge of the substrate W (refer to the area 602 in FIG. 6), and small in the case that the measurement points are those in the part on the inner side of the part near the edge of the substrate W (refer to the area 604 in FIG. 6). With respect to pieces of measurement data, in the all pieces of measurement data, that have been judged as those satisfying the condition that a difference between pieces of measurement data corresponding to adjacent measurement points on the path is larger than the predetermined threshold value, that is, with respect to a range of the pieces of measurement data corresponding to the part near the edge of the substrate W, the processor 122 applies thereto an interpolation process using a first interpolation pitch in step 812. On the other hand, with respect to pieces of measurement data, in the all pieces of measurement data, that have been judged as those satisfying a condition that a difference between pieces of measurement data corresponding to adjacent measurement points on the path is smaller than the predetermined threshold value, that is, with respect to a range of the pieces of measurement data corresponding to the part on the inner side of the part near the edge of the substrate W, the processor 122 applies thereto an interpolation process using a second interpolation pitch in step 814. In this regard, similar to the case of the above-explained embodiment, the first interpolation pitch is that narrower than the second interpolation pitch. In a manner similar to that in the above-explained embodiment, a film thickness profile of the film on the substrate W along the path corresponding to the measurement data is created by using the result of interpolation (step 816).

[0049] As explained above and similar to the above-explained embodiment, according to the present embodiment, it becomes possible to draw an accurate film thickness profile with respect to the part near the edge of the substrate W, where change in measurement data is large, by applying thereto an interpolation process using a narrow interpolation pitch, and reduce a calculation load relating to interpolation with respect to the part on the inner side of the substrate W, where change in measurement data is small, by applying thereto an interpolation process using a wide interpolation pitch.

[0050] FIG. 9 is a flow chart which shows operation of the polishing apparatus 10 according to the other different embodiment of the present invention. A process in each of steps in the flow chart in FIG. 9 is performed by the processor 122 in the controller 120 in the film thickness measuring apparatus 100. The method according to the embodiment in FIG. 9 starts from step 902 during an operation preparing stage of the polishing apparatus 10. In this regard, the processes performed in steps 904, 906, 908, 916, 918, and 920 in the flow chart in FIG. 9 are similar to those performed in steps 404, 406, 408, 416, 418, and 420 in the above-explained flow chart in FIG. 4, respectively; and explanation thereof may be omitted accordingly.

[0051] In step 902, the processor 122 obtains a reference profile with respect to film thickness along a predetermined path on the substrate W. For example, multiple substrates Ws may be polished in advance, and a reference profile of film thickness relating to various paths on the substrate W may be created by using measurement data obtained from the sensor 110. For example, a reference profile may be calculated by averaging many pieces of measurement data obtained by polishing multiple substrates Ws in advance. Alternatively, a reference profile may be that inferred as a most probable film thickness profile by a machine learning model (for example, a neural network) trained by using many pieces of measurement data obtained by polishing multiple substrates Ws in advance.

[0052] In step 910, based on pieces of measurement data obtained from the sensor 110, the processor 122 makes a judgment as to whether a deviation of each of the pieces of measurement data from a related part in the reference profile is larger than a predetermined threshold value. FIG. 10 is a schematic drawing which shows examples of a reference profile and measurement data. In the example in FIG. 10, regarding a series of pieces of measurement data 1002 shown by a series of circles, a deviation of each of the pieces of measurement data in data ranges 1006 and 1008 from a related part in the reference profile is larger than the predetermined threshold value, and a deviation of each of the pieces of measurement data in data ranges 1010 and 1012 from a related part in the reference profile is smaller than the predetermined threshold value. With respect to a series of pieces of measurement data, in all pieces of measurement data, that has been judged as that satisfying the condition that the deviation of each of the pieces of measurement data from the related part in the reference profile is larger than the predetermined threshold value (for example, the measurement data in the data ranges 1006 and 1008 in FIG. 10), the processor 122 applies to the series of pieces of measurement data an interpolation process using a first interpolation pitch in step 912. On the other hand, with respect to a series of pieces of measurement data, in all pieces of measurement data, that has been judged as that satisfying the condition that the deviation of each of the pieces of measurement data from the related part in the reference profile is smaller than the predetermined threshold value (for example, the measurement data in the data ranges 1010 and 1012 in FIG. 10), the processor 122 applies to the series of pieces of measurement data an interpolation process using a second interpolation pitch in step 914. In this regard, similar to the case of each of the above-explained embodiments, the first interpolation pitch is that narrower than the second interpolation pitch. In a manner similar to that in each of the above-explained embodiments, a film thickness profile of the film on the substrate W along the path corresponding to the measurement data is created by using the result of interpolation (step 916).

[0053] As explained above, according to the present embodiment, it becomes possible to draw an accurate film thickness profile with respect to a part where change in measurement data relative to a reference profile is large, by applying thereto an interpolation process using a narrow interpolation pitch, and reduce a calculation load relating to interpolation with respect to the part where change in measurement data is small, by applying thereto an interpolation process using a wide interpolation pitch.

[0054] FIG. 11 is a flow chart which shows operation of the polishing apparatus 10 according to a further different embodiment of the present invention. A process in each of steps in the flow chart in FIG. 11 is performed by the processor 122 in the controller 120 in the film thickness measuring apparatus 100. At the time when operation of the polishing apparatus 10 starts, the method according to the embodiment in FIG. 11 starts from step 1102. In this regard, the processes performed in steps 1104, 1106, 1108, 1116, 1118, and 1120 in the flow chart in FIG. 11 are similar to those performed in steps 404, 406, 408, 416, 418, and 420 in the above-explained flow chart in FIG. 4, respectively; and explanation thereof may be omitted accordingly.

[0055] In step 1104, the polishing apparatus 10 starts polishing of a substrate W. After a start of polishing of the substrate W, the processor 122 obtains, in step 1105, data representing the speed of rotation of the polishing table 30. For example, the data representing the speed of rotation of the polishing table 30 may be obtained from a rotation speed sensor (which is not shown in the figures) of any type which is able to detect the speed of rotation of the polishing table 30, or may be given as a user input for designating a polishing condition(s) with respect to the polishing apparatus 10. In addition to the data representing the speed of rotation of the polishing table 30, or in place of the data representing the speed of rotation of the polishing table 30, data representing the speed of rotation of the top ring 40 (a polishing head) may be obtained by using a method similar to that explained above. In this regard, the speed of rotation of each of the polishing table 30 and the top ring 40 may dynamically change according to progress in polishing of the substrate W and resultant change in the polishing condition.

[0056] In step 1110, based on the rotation speed data obtained in step 1105, the processor 122 makes a judgment as to whether the speed of rotation of the polishing table 30 (and / or the speed of rotation of the top ring 40) is faster than a rotation speed corresponding to a predetermined threshold value. In the case that the rotation speed is fast, it is assumed that a time margin usable for performing an interpolation process with respect to the measurement data may not be long enough. Accordingly, in the present embodiment, an interpolation pitch used in an interpolation process applied to the measurement data obtained during the time when the rotation speed is fast is made wider than an interpolation pitch used in an interpolation process applied to the measurement data obtained during the time when the rotation speed is slow. Accordingly, with respect to measurement data that has been obtained during the time when the speed of rotation of the polishing table 30 (and / or the speed of rotation of the top ring 40) is slower than the rotation speed corresponding to the predetermined threshold value, an interpolation process using a first interpolation pitch is applied thereto in step 1112. On the other hand, with respect to measurement data that has been obtained during the time when the speed of rotation of the polishing table 30 (and / or the speed of rotation of the top ring 40) is faster than the rotation speed corresponding to the predetermined threshold value, an interpolation process using a second interpolation pitch is applied thereto in step 1114. In this regard, similar to each of the cases of the above-explained embodiments, the first interpolation pitch is that narrower than the second interpolation pitch. In a manner similar to that in each of the above-explained embodiments, a film thickness profile of the film on the substrate W along the path corresponding to the measurement data is created by using the result of interpolation (step 1116).

[0057] As explained above, according to the present embodiment, it becomes possible to draw an accurate film thickness profile by performing an interpolation process using a narrow interpolation pitch in the case that the speed of rotation of the polishing table 30 and / or the speed of rotation of the top ring 40 are / is slow, and reduce a calculation load relating to interpolation by performing an interpolation process using a wide interpolation pitch in the case that the speed of rotation of the polishing table 30 and / or the speed of rotation of the top ring 40 are / is fast.

[0058] In the above description, embodiments of the present invention have been explained based on some examples; and, in this regard, the above explained embodiments of the present invention are those used for facilitating understanding of the present invention, and are not those used for limiting the present invention. It is obvious that the present invention can be changed or modified without departing from the scope of the gist thereof, and that the present invention includes equivalents thereof. Further, it is possible to arbitrarily combine components or omit a component(s) disclosed in the claims and the specification, within the scope that at least part of the above-stated problems can be solved or within the scope that at least part of advantageous effect can be obtained.REFERENCE SIGNS LIST

[0059] 10 Polishing apparatus

[0060] 30 Polishing table

[0061] 31 Polishing pad

[0062] 311 Polishing surface

[0063] 32 Table shaft

[0064] 40 Top ring

[0065] 41A Retainer ring

[0066] 41B Top-ring main body

[0067] 42 Top ring shaft

[0068] 43 Top ring driving motor

[0069] 50 Arm

[0070] 52 Arm shaft

[0071] 53 Arm driving motor

[0072] 61 Rotary cylinder

[0073] 62 Timing pulley

[0074] 63 Timing belt

[0075] 64 Timing pulley

[0076] 100 Film thickness measuring apparatus

[0077] 110 Sensor

[0078] 120 Controller

[0079] 122 Processor

[0080] 124 Memory

[0081] 126 Program

Examples

Embodiment Construction

[0029]In the following description, embodiments of the present invention will be explained with reference to the figures. In the figures which will be explained in the following description, a reference symbol assigned to one component is also assigned to the other component if the other component is the same as or corresponds to the one component, and overlapping explanation of these components will be omitted.

[0030]FIG. 1 is a schematic drawing which shows a construction of a polishing apparatus 10 according to an embodiment of the present invention. As shown in the figure, the polishing apparatus 10 comprises a polishing table 30 for holding a polishing pad 31, and a top ring 40 (a polishing head) for holding a substrate (a wafer) W, which is an object of polishing, in such a manner that the substrate faces the polishing pad 31, and pushing the substrate to a polishing surface of the polishing pad 31.

[0031]The polishing table 30 is connected, via a table shaft 32, to a table driv...

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims priority from Japanese Patent Application No. 2025-048164, filed on Mar. 24, 2025, with the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.TECHNICAL FIELD

[0002] The present invention relates to a polishing apparatus and a method for creating a film thickness profile in a polishing apparatus.BACKGROUND

[0003] There is a CMP (Chemical Mechanical Polishing) apparatus in apparatuses for manufacturing semiconductor devices. A representative CMP apparatus comprises a polishing table to which a polishing pad is attached, and a polishing head to which a substrate is attached. In the representative CMP apparatus, a substrate is polished by supplying a polishing liquid to the polishing pad, and rotating, in the state that the polishing pad and the substrate are in contact with each other, at least one of the polishing table and the polishing head.

[0004] During the time when a substrate is being polished, a sensor such as an eddy current sensor installed in a polishing table, for example, is used for measuring thickness of a film which is an object of polishing. The sensor moves along a path on a surface of a substrate as a polishing table rotates, and measures film thickness at each of points on the path. A film thickness profile that represents film thickness distribution on the substrate can be created based on data of film thickness measurement at the respective points on the path (for example, refer to Japanese Patent Laid-Open Publication No. 2022-510757).SUMMARY OF INVENTION

[0005] A sensor obtains film thickness measurement data at discrete measurement points on a substrate. For improving definition of a film thickness profile, an interpolation process may be applied to the measurement data obtained at the discrete measurement points. However, the interpolation process requires a certain calculation load. In other words, improvement of definition of a film thickness profile and the quantity of the calculation load are in a trade-off relationship.

[0006] According to an embodiment, a polishing apparatus is provided: wherein the polishing apparatus comprises a polishing table which is provided with a sensor and constructed to be able to rotate; a polishing head which is arranged to face the polishing table, constructed to be able to rotate, and constructed to allow a substrate to be attached to a surface facing the polishing table; and a controller: wherein the sensor is constructed to output, when the sensor passes a path on the substrate, time series data that comprises a series of pieces of measurement data relating to film thicknesses at multiple measurement points on the path: and the controller is constructed to obtain the time series data from the sensor; apply interpolation using a first interpolation pitch to the measurement data in a first data range in the time series data; apply interpolation using a second interpolation pitch, that is different from the first interpolation pitch, to the measurement data in a second data range in the time series data; and create a film thickness profile corresponding to the path, based on the interpolated measurement data in the first data range and the second data range.

[0007] In the above embodiment, each of the interpolation using the first interpolation pitch and the interpolation using the second interpolation pitch may include a process for creating, based on the measurement data obtained at the multiple measurement points on the path, interpolation data for one or multiple interpolation points between the multiple measurement points on the path.

[0008] In the above embodiment, each of the first interpolation pitch and the second interpolation pitch may represent a distance between the interpolation points or a distance between the interpolation point and the measurement point.

[0009] In the above embodiments, the first data range may correspond to a part near an edge of the substrate, the second data range may correspond to a part on an inner side of the part near the edge of the substrate, and the first interpolation pitch may be narrower than the second interpolation pitch.

[0010] In the above embodiment, the controller may further be constructed to accept a user input for designating the first data range and the second data range.

[0011] In the above embodiments, the controller may further be constructed to judge that successive pieces of measurement data corresponding to adjacent measurement points on the path, in the time series data, belong to the first data range, if a difference between the successive pieces of measurement data is larger than a predetermined value, and judge that successive pieces of measurement data corresponding to adjacent measurement points on the path, in the time series data, belong to the second data range, if a difference between the successive pieces of measurement data is smaller than a predetermined value; wherein the first interpolation pitch is narrower than the second interpolation pitch.

[0012] In the above embodiments, the controller may further be constructed to obtain a reference profile with respect to film thickness relating to the path on the substrate, judge that pieces of measurement data in the time series data belong to the first data range, if each of deviations of the pieces of measurement data from related parts in the reference profile is larger than a predetermined value, and judge that pieces of measurement data in the time series data belong to the second data range, if each of deviations of the pieces of measurement data from related parts in the reference profile is smaller than the predetermined value; wherein the first interpolation pitch is narrower than the second interpolation pitch.

[0013] In the above embodiment, the reference profile may be created in advance by using measurement data obtained from the sensor when multiple substrates were polished.

[0014] In the above embodiments, the controller may further be constructed to obtain data representing a speed of rotation of the polishing table or a speed of rotation of the polishing head, judge that pieces of measurement data in the time series data belong to the first data range, if the speed of rotation when the pieces of measurement data are obtained is slower than a predetermined speed of rotation, and judge that pieces of measurement data in the time series data belong to the second data range, if the speed of rotation when the pieces of measurement data are obtained is faster than the predetermined speed of rotation; wherein the first interpolation pitch is narrower than the second interpolation pitch.

[0015] In the above embodiment, the data representing the speed of rotation may be obtained from a rotation speed sensor, or may be designated by a user input.

[0016] In the above embodiments, the controller may further be constructed to display the created film thickness profile on a display.

[0017] According to a further embodiment, a method for creating a film thickness profile in a polishing apparatus is provided: wherein the polishing apparatus comprises a polishing table which is provided with a sensor and constructed to be able to rotate, and a polishing head which is arranged to face the polishing table, constructed to be able to rotate, and constructed to allow a substrate to be attached to a surface facing the polishing table; and the method comprises steps for outputting, by the sensor when the sensor passes a path on the substrate, time series data that comprises a series of pieces of measurement data relating to film thicknesses at multiple measurement points on the path, obtaining the time series data from the sensor, applying interpolation using a first interpolation pitch to the measurement data in a first data range in the time series data, applying interpolation using a second interpolation pitch, that is different from the first interpolation pitch, to the measurement data in a second data range in the time series data, and creating a film thickness profile corresponding to the path, based on the interpolated measurement data in the first data range and the second data range.BRIEF DESCRIPTION OF DRAWINGS

[0018] FIG. 1 is a schematic drawing which shows a construction of a polishing apparatus according to an embodiment of the present invention.

[0019] FIG. 2 is a schematic drawing which shows an example path of a sensor.

[0020] FIG. 3 is a figure which shows a construction of a controller in a film thickness measuring apparatus, in a polishing apparatus according to an embodiment of the present invention.

[0021] FIG. 4 is a flow chart which shows operation of a polishing apparatus according to an embodiment of the present invention.

[0022] FIG. 5 is a schematic drawing which shows a part near an edge of a substrate.

[0023] FIG. 6 is a schematic drawing which is based on example measurement data and is to be used for explaining an interpolation process.

[0024] FIG. 7 is an additional explanatory drawing relating to the interpolation process.

[0025] FIG. 8 is a flow chart which shows operation of a polishing apparatus according to a different embodiment of the present invention.

[0026] FIG. 9 is a flow chart which shows operation of a polishing apparatus according to the other different embodiment of the present invention.

[0027] FIG. 10 is a schematic drawing which shows examples of a reference profile and measurement data.

[0028] FIG. 11 is a flow chart which shows operation of a polishing apparatus according to a further different embodiment of the present invention.DESCRIPTION OF EMBODIMENTS

[0029] In the following description, embodiments of the present invention will be explained with reference to the figures. In the figures which will be explained in the following description, a reference symbol assigned to one component is also assigned to the other component if the other component is the same as or corresponds to the one component, and overlapping explanation of these components will be omitted.

[0030] FIG. 1 is a schematic drawing which shows a construction of a polishing apparatus 10 according to an embodiment of the present invention. As shown in the figure, the polishing apparatus 10 comprises a polishing table 30 for holding a polishing pad 31, and a top ring 40 (a polishing head) for holding a substrate (a wafer) W, which is an object of polishing, in such a manner that the substrate faces the polishing pad 31, and pushing the substrate to a polishing surface of the polishing pad 31.

[0031] The polishing table 30 is connected, via a table shaft 32, to a table driving motor (which is not shown in the figure) positioned below the table shaft 32. The table driving motor is driven to rotate, and, accordingly, the polishing table 30 is able to rotate about an axis of the table shaft 32. The polishing pad 31 is attached to a top surface of the polishing table 30. A surface 311 of the polishing pad 31 comprises a polishing surface for polishing the wafer W. A polishing liquid supplying nozzle, which is not shown in the figure, is arranged in a position above the polishing table 30, and a polishing liquid is supplied from the polishing liquid supplying nozzle to the polishing pad 31 on the polishing table 30.

[0032] The top ring 40 is supported by an arm 50 via a top ring shaft 42. By using an up-and-down motion mechanism which is not shown in the figure, the top ring shaft 42 is able to move upward and downward in relation to the arm 50. Positioning of the top ring 40 relative to the arm 50 may be performed by moving the top ring 40 upward / downward by making the top ring shaft 40 move upward and downward. The top ring 40 is constructed to hold, on its bottom surface, the wafer W. Specifically, as shown in FIG. 1, the top ring 40 comprises a retainer ring 41A which holds an outer peripheral edge of the wafer W to prevent the wafer W from jumping out of the top ring 40, and a top-ring main body 41B which pushes the wafer W to the polishing surface 311.

[0033] A top ring driving motor 43 is fixed to the arm 50 which supports the top ring 40. Further, as shown in FIG. 1, the top ring shaft 42 is connected to a rotary cylinder 61; and a timing pulley 62 installed on an outer periphery of the rotary cylinder 61 is connected, via a timing belt 63, to a timing pulley 64 installed on the top ring driving motor 43. According to the above construction, as the top ring driving motor 43 rotates, the rotary cylinder 61 and the top ring shaft 42 integrally rotates via the timing pulley 64, the timing belt 63, and the timing pulley 62; and the top ring 40 rotates about the axis of the top ring shaft 42.

[0034] The arm 50 is connected to an arm driving motor 53 which is fixed to an arm shaft 52. The arm 50 and the top ring 40 supported by the arm 50 are able to rotate about the axis of the arm shaft 52 by driving the arm driving motor 53.

[0035] When the polishing apparatus 10 performs action, first, the top ring 40 receives, at a predetermined receiving position, the wafer W conveyed by a conveyance mechanism which is not shown in the figure, and holds the wafer W. The top ring 40, which has received the wafer W at the receiving position, is moved from the receiving position to a position above the polishing table 30 by rotational movement of the arm 50. Next, the top ring shaft 42 and the top ring 40 are moved downward, and, accordingly, the wafer W is pushed to the polishing surface 311 of the polishing pad 31. Thereafter, the table driving motor and the top ring driving motor 43 are driven to rotate them to thereby rotate the polishing table 30 and the top ring 40, respectively; and, at the same time, a polishing liquid is supplied on the polishing pad 31 from the polishing liquid supplying nozzle installed in a position above the polishing table 30. According to the above construction, the wafer W is brought into contact, in a sliding contact manner, with the polishing surface 311 of the polishing pad 31, and the surface of the wafer W is polished accordingly. During polishing of the wafer W, polishing may be performed in such a manner that the top ring 40 is moved in a swinging manner relative to the polishing pad 31 (i.e., it is moved back and forth on the polishing pad 31) by making the arm 50 periodically swing to the left and to the right by the arm driving motor 53.

[0036] In an embodiment of the present invention, the polishing apparatus 10 further comprises a film thickness measuring apparatus 100 for measuring thickness of a film on the substrate W when it is being polished by the polishing apparatus 10. The film thickness measuring apparatus 100 comprises a sensor 110 installed in the polishing apparatus 10, and a controller 120 for processing signals from the sensor 110 to create a film thickness profile. The sensor 110 may be a sensor of any type, such as an eddy current sensor, an optical sensor, an acoustic sensor, an ultrasonic sensor, or the like which can measure thickness of a film on the substrate W. The sensor 110 may be installed in a part that is in the inside of the polishing table 30 and is near the substrate W, as shown in FIG. 1, for example. During the time when the substrate W is being polished by operating the polishing table 30 and the top ring 40 to rotate them, the sensor 110 moves, on the substrate W, along an arc-shaped path that is determined according rotation of the polishing table 30 and the top ring 40.

[0037] FIG. 2 is a schematic drawing which shows an example path of the sensor 110. During each single rotation of the polishing table 30, the sensor 110 crosses the surface of the substrate W along an arc-shaped path 202 having a predetermined curvature, and outputs pieces of measurement data relating to film thickness at respective measurement points 204 that are arranged at predetermined intervals on the path 202. The sensor 110 is connected to the controller 120 to electrically communicate with it; and time series data, that is outputted from the sensor 110 and comprises a series of pieces of measurement data corresponding to the multiple measurement points 204 on the path 202, is supplied to the controller 120. The controller 120 is able to create, based on the series of pieces of measurement data from the sensor 110, a film thickness profile of a film on the substrate W which is being polished by the polishing apparatus 10.

[0038] FIG. 3 is a figure which shows a construction of the controller 120 in the film thickness measuring apparatus 100 in the above-explained polishing apparatus 10 according to an embodiment of the present invention. The controller 120 comprises a processor 122 and a memory 124. The memory 124 stores a program 126 (computer executable instructions) for realizing a method according to an embodiment of the present invention. The processor 122 reads the program 126 out of the memory 124 and executes it. As a result, the method according to the embodiment of the present invention is realized.

[0039] FIG. 4 is a flow chart which shows operation of the polishing apparatus 10 according to an embodiment of the present invention. A process in each of steps in the flow chart in FIG. 4 is performed by the processor 122 in the controller 120 in the film thickness measuring apparatus 100. The method according to the embodiment in FIG. 4 starts from step 402 during an operation preparing stage of the polishing apparatus 10.

[0040] In step 402, the processor 122 receives a user input that designates an interpolation condition(s) for performing interpolation of the measurement data outputted from the sensor 110. The interpolation condition includes information relating to an interpolation pitch that is used when performing interpolation of the measurement data outputted from the sensor 110. Specifically, with respect to a time series data comprising a series of pieces of measurement data obtained from the sensor 110, the interpolation condition represents a range in the pieces of the measurement data to that an interpolation process using a first interpolation pitch should be applied, and a range in the pieces of the measurement data to that an interpolation process using a second interpolation pitch should be applied. For example, a user input may be that for designating a condition such that pieces of measurement data corresponding to a belt-shaped area 504 that is close to an edge 502 of the substrate W and has a width d as shown in FIG. 5 is to be subjected to an interpolation process using a first interpolation pitch, and pieces of measurement data corresponding to a center area 506 positioned on an inner side of the area 504 is to be subjected to an interpolation process using a second interpolation pitch.

[0041] Next, in step 404, the polishing apparatus 10 starts polishing of the substrate W. In step 406 that follows the above step, as the sensor 110 moves along a path (for example, the path 202 in FIG. 2) on the substrate W, the processor 122 sequentially obtains, from the sensor 110, respective pieces of measurement data obtained at respective measurement points (for example, the respective points 204 in FIG. 2) on the path. Further, in step 408, the processor 122 calculates, from each of the obtained pieces of measurement data, film thickness at each of the measurement points.

[0042] Next, in step 410, based on the interpolation condition designated in step 402, the processor 122 makes a judgment as to whether each of measurement points relating to the series of pieces of measurement data obtained by the sensor 110 is in a position in the part near the edge of the substrate W. With respect to a range of pieces of measurement data, in the whole range of pieces of measurement data, that relates to measurement points positioned in the part near the edge of the substrate W (for example, the belt-shaped area 514 in FIG. 5), the processor 122 applies thereto the interpolation process using the first interpolation pitch in step 412. On the other hand, with respect to a range of pieces of measurement data, in the whole range of pieces of measurement data, that relates to measurement points positioned in the part on the inner side of the above part near the edge of the substrate W (for example, the area 506 in FIG. 5), the processor 122 applies thereto the interpolation process using the second interpolation pitch in step 414. In the present case, the first interpolation pitch is that narrower than the second interpolation pitch.

[0043] FIG. 6 is a schematic drawing which is based on example measurement data and is to be used for explaining the interpolation processes performed in steps 412 and 414. A horizontal axis of a graph in FIG. 6 represents positions on the substrate W along a path, and a vertical axis represents film thickness values. In the graph in FIG. 6, a position X0 corresponds to an edge of the substrate W (the edge 502 in FIG. 5), and a range 602 between the position X0 and a position X1, that is positioned on an inner side of the substrate W and separate from the position X0 by a distance d, corresponds to the part near the edge of the substrate W (the belt-shaped area 504 in FIG. 5). As shown in FIG. 6, the processor 122 applies an interpolation process using a first interpolation pitch p1 to the measurement data in the range 602 that corresponds to the part near the edge of the substrate W. Further, the processor 122 applies an interpolation process using a second interpolation pitch p2 to the measurement data in the range 604 that corresponds to the part positioned on the inner side of the part near the edge of the substrate W (the area 506 in FIG. 5). In this regard, an interpolation pitch refers to a distance between interpolation points shown by multiple circles in FIG. 6 or a distance between an interpolation point and a measurement point, and an interpolation point(s) refers to a point(s) for interpolation between the measurement points. For example, the first interpolation pitch p1 may be 0.1 mm and the second interpolation pitch p2 may be 1 mm; and, in this regard, the above values are mere examples so that the values are not limited to the above values.

[0044] FIG. 7 is an additional explanatory drawing relating to the interpolation process. As explained above, the processor 122 obtains a series of pieces of measurement data MD1, MD2, MD3, and so on from the sensor 110. Measurement points mx1, mx2, mx3, and so on corresponding to the pieces of measurement data correspond to the measurement points 204 on the sensor path 202 shown in FIG. 2, respectively. The processor 122 performs the interpolation process by creating, based on the pieces of measurement data MD1, MD2, MD3, and so on, pieces of interpolation data ID1, ID2, ID3, and so on as those corresponding to multiple interpolation points ix1, ix2, ix3, and so on that are set in positions whereat a distance between adjacent measurement points in measurement points mx1, mx2, mx3, and so on is divided into distances, each distance corresponding to a predetermined interpolation pitch (the first interpolation pitch p1 or the second interpolation pitch p2). In this regard, any interpolation algorithm such as linear interpolation, spline interpolation, or the like, may be applicable to the method for creating interpolation data from measurement data.

[0045] The flow chart in FIG. 4 will be referred to again herein; and, next, in step 416, the processor 122 creates, by using the result of interpolation, a film thickness profile of the film on the substrate W along the path corresponding to the measurement data. FIG. 6 shows an example film thickness profile PF created in the manner explained above. The created film thickness profile (for example, visual representation using a graph such as the film thickness profile PF shown in FIG. 6) is displayed on a display device which is associated with the polishing device 10 or is arranged in a remote position, for allowing an operator of the polishing apparatus 10 to check the state of polishing of the substrate W, the state of progress in polishing, and so on. Next, in step 418, based on the film thickness profile, the processor 122 makes a judgment as to whether polishing of the substrate W has been completed. For example, a decision to terminate the polishing process may be made in response to a state that the film thickness profile has become that having a desired degree of flatness, and / or a state that the film thickness has become a desired thickness. If a predetermined termination condition is satisfied, the polishing apparatus 10 terminates, in step 420, the polishing process applied to the substrate W.

[0046] As explained above, according to the present embodiment, it becomes possible to draw an accurate film thickness profile with respect to the part near the edge of the substrate W, where change in measurement data is large, by applying thereto an interpolation process using a narrow interpolation pitch, and reduce a calculation load relating to interpolation with respect to the part on the inner side of the substrate W, where change in measurement data is small, by applying thereto an interpolation process using a wide interpolation pitch.

[0047] FIG. 8 is a flow chart which shows operation of the polishing apparatus 10 according to a different embodiment of the present invention. A process in each of steps in the flow chart in FIG. 8 is performed by the processor 122 in the controller 120 in the film thickness measuring apparatus 100. At the time when operation of the polishing apparatus 10 starts, the method according to the embodiment in FIG. 8 starts from step 804. In this regard, the processes performed in steps 804, 806, 808, 816, 818, and 820 in the flow chart in FIG. 8 are similar to those performed in steps 404, 406, 408, 416, 418, and 420 in the above-explained flow chart in FIG. 4, respectively; and explanation thereof may be omitted accordingly.

[0048] In step 810, based on the pieces of measurement data obtained by the sensor 110, the processor 122 makes a judgment as to whether a difference between pieces of measurement data corresponding to measurement points in each of pairs of adjacent measurement points on the path is larger than a predetermined threshold value. As can be seen from the above-explained FIG. 6, the difference between pieces of measurement data corresponding to the adjacent measurement points on the path is large in the case that the measurement points are those in the part near the edge of the substrate W (refer to the area 602 in FIG. 6), and small in the case that the measurement points are those in the part on the inner side of the part near the edge of the substrate W (refer to the area 604 in FIG. 6). With respect to pieces of measurement data, in the all pieces of measurement data, that have been judged as those satisfying the condition that a difference between pieces of measurement data corresponding to adjacent measurement points on the path is larger than the predetermined threshold value, that is, with respect to a range of the pieces of measurement data corresponding to the part near the edge of the substrate W, the processor 122 applies thereto an interpolation process using a first interpolation pitch in step 812. On the other hand, with respect to pieces of measurement data, in the all pieces of measurement data, that have been judged as those satisfying a condition that a difference between pieces of measurement data corresponding to adjacent measurement points on the path is smaller than the predetermined threshold value, that is, with respect to a range of the pieces of measurement data corresponding to the part on the inner side of the part near the edge of the substrate W, the processor 122 applies thereto an interpolation process using a second interpolation pitch in step 814. In this regard, similar to the case of the above-explained embodiment, the first interpolation pitch is that narrower than the second interpolation pitch. In a manner similar to that in the above-explained embodiment, a film thickness profile of the film on the substrate W along the path corresponding to the measurement data is created by using the result of interpolation (step 816).

[0049] As explained above and similar to the above-explained embodiment, according to the present embodiment, it becomes possible to draw an accurate film thickness profile with respect to the part near the edge of the substrate W, where change in measurement data is large, by applying thereto an interpolation process using a narrow interpolation pitch, and reduce a calculation load relating to interpolation with respect to the part on the inner side of the substrate W, where change in measurement data is small, by applying thereto an interpolation process using a wide interpolation pitch.

[0050] FIG. 9 is a flow chart which shows operation of the polishing apparatus 10 according to the other different embodiment of the present invention. A process in each of steps in the flow chart in FIG. 9 is performed by the processor 122 in the controller 120 in the film thickness measuring apparatus 100. The method according to the embodiment in FIG. 9 starts from step 902 during an operation preparing stage of the polishing apparatus 10. In this regard, the processes performed in steps 904, 906, 908, 916, 918, and 920 in the flow chart in FIG. 9 are similar to those performed in steps 404, 406, 408, 416, 418, and 420 in the above-explained flow chart in FIG. 4, respectively; and explanation thereof may be omitted accordingly.

[0051] In step 902, the processor 122 obtains a reference profile with respect to film thickness along a predetermined path on the substrate W. For example, multiple substrates Ws may be polished in advance, and a reference profile of film thickness relating to various paths on the substrate W may be created by using measurement data obtained from the sensor 110. For example, a reference profile may be calculated by averaging many pieces of measurement data obtained by polishing multiple substrates Ws in advance. Alternatively, a reference profile may be that inferred as a most probable film thickness profile by a machine learning model (for example, a neural network) trained by using many pieces of measurement data obtained by polishing multiple substrates Ws in advance.

[0052] In step 910, based on pieces of measurement data obtained from the sensor 110, the processor 122 makes a judgment as to whether a deviation of each of the pieces of measurement data from a related part in the reference profile is larger than a predetermined threshold value. FIG. 10 is a schematic drawing which shows examples of a reference profile and measurement data. In the example in FIG. 10, regarding a series of pieces of measurement data 1002 shown by a series of circles, a deviation of each of the pieces of measurement data in data ranges 1006 and 1008 from a related part in the reference profile is larger than the predetermined threshold value, and a deviation of each of the pieces of measurement data in data ranges 1010 and 1012 from a related part in the reference profile is smaller than the predetermined threshold value. With respect to a series of pieces of measurement data, in all pieces of measurement data, that has been judged as that satisfying the condition that the deviation of each of the pieces of measurement data from the related part in the reference profile is larger than the predetermined threshold value (for example, the measurement data in the data ranges 1006 and 1008 in FIG. 10), the processor 122 applies to the series of pieces of measurement data an interpolation process using a first interpolation pitch in step 912. On the other hand, with respect to a series of pieces of measurement data, in all pieces of measurement data, that has been judged as that satisfying the condition that the deviation of each of the pieces of measurement data from the related part in the reference profile is smaller than the predetermined threshold value (for example, the measurement data in the data ranges 1010 and 1012 in FIG. 10), the processor 122 applies to the series of pieces of measurement data an interpolation process using a second interpolation pitch in step 914. In this regard, similar to the case of each of the above-explained embodiments, the first interpolation pitch is that narrower than the second interpolation pitch. In a manner similar to that in each of the above-explained embodiments, a film thickness profile of the film on the substrate W along the path corresponding to the measurement data is created by using the result of interpolation (step 916).

[0053] As explained above, according to the present embodiment, it becomes possible to draw an accurate film thickness profile with respect to a part where change in measurement data relative to a reference profile is large, by applying thereto an interpolation process using a narrow interpolation pitch, and reduce a calculation load relating to interpolation with respect to the part where change in measurement data is small, by applying thereto an interpolation process using a wide interpolation pitch.

[0054] FIG. 11 is a flow chart which shows operation of the polishing apparatus 10 according to a further different embodiment of the present invention. A process in each of steps in the flow chart in FIG. 11 is performed by the processor 122 in the controller 120 in the film thickness measuring apparatus 100. At the time when operation of the polishing apparatus 10 starts, the method according to the embodiment in FIG. 11 starts from step 1102. In this regard, the processes performed in steps 1104, 1106, 1108, 1116, 1118, and 1120 in the flow chart in FIG. 11 are similar to those performed in steps 404, 406, 408, 416, 418, and 420 in the above-explained flow chart in FIG. 4, respectively; and explanation thereof may be omitted accordingly.

[0055] In step 1104, the polishing apparatus 10 starts polishing of a substrate W. After a start of polishing of the substrate W, the processor 122 obtains, in step 1105, data representing the speed of rotation of the polishing table 30. For example, the data representing the speed of rotation of the polishing table 30 may be obtained from a rotation speed sensor (which is not shown in the figures) of any type which is able to detect the speed of rotation of the polishing table 30, or may be given as a user input for designating a polishing condition(s) with respect to the polishing apparatus 10. In addition to the data representing the speed of rotation of the polishing table 30, or in place of the data representing the speed of rotation of the polishing table 30, data representing the speed of rotation of the top ring 40 (a polishing head) may be obtained by using a method similar to that explained above. In this regard, the speed of rotation of each of the polishing table 30 and the top ring 40 may dynamically change according to progress in polishing of the substrate W and resultant change in the polishing condition.

[0056] In step 1110, based on the rotation speed data obtained in step 1105, the processor 122 makes a judgment as to whether the speed of rotation of the polishing table 30 (and / or the speed of rotation of the top ring 40) is faster than a rotation speed corresponding to a predetermined threshold value. In the case that the rotation speed is fast, it is assumed that a time margin usable for performing an interpolation process with respect to the measurement data may not be long enough. Accordingly, in the present embodiment, an interpolation pitch used in an interpolation process applied to the measurement data obtained during the time when the rotation speed is fast is made wider than an interpolation pitch used in an interpolation process applied to the measurement data obtained during the time when the rotation speed is slow. Accordingly, with respect to measurement data that has been obtained during the time when the speed of rotation of the polishing table 30 (and / or the speed of rotation of the top ring 40) is slower than the rotation speed corresponding to the predetermined threshold value, an interpolation process using a first interpolation pitch is applied thereto in step 1112. On the other hand, with respect to measurement data that has been obtained during the time when the speed of rotation of the polishing table 30 (and / or the speed of rotation of the top ring 40) is faster than the rotation speed corresponding to the predetermined threshold value, an interpolation process using a second interpolation pitch is applied thereto in step 1114. In this regard, similar to each of the cases of the above-explained embodiments, the first interpolation pitch is that narrower than the second interpolation pitch. In a manner similar to that in each of the above-explained embodiments, a film thickness profile of the film on the substrate W along the path corresponding to the measurement data is created by using the result of interpolation (step 1116).

[0057] As explained above, according to the present embodiment, it becomes possible to draw an accurate film thickness profile by performing an interpolation process using a narrow interpolation pitch in the case that the speed of rotation of the polishing table 30 and / or the speed of rotation of the top ring 40 are / is slow, and reduce a calculation load relating to interpolation by performing an interpolation process using a wide interpolation pitch in the case that the speed of rotation of the polishing table 30 and / or the speed of rotation of the top ring 40 are / is fast.

[0058] In the above description, embodiments of the present invention have been explained based on some examples; and, in this regard, the above explained embodiments of the present invention are those used for facilitating understanding of the present invention, and are not those used for limiting the present invention. It is obvious that the present invention can be changed or modified without departing from the scope of the gist thereof, and that the present invention includes equivalents thereof. Further, it is possible to arbitrarily combine components or omit a component(s) disclosed in the claims and the specification, within the scope that at least part of the above-stated problems can be solved or within the scope that at least part of advantageous effect can be obtained.REFERENCE SIGNS LIST

[0059] 10 Polishing apparatus

[0060] 30 Polishing table

[0061] 31 Polishing pad

[0062] 311 Polishing surface

[0063] 32 Table shaft

[0064] 40 Top ring

[0065] 41A Retainer ring

[0066] 41B Top-ring main body

[0067] 42 Top ring shaft

[0068] 43 Top ring driving motor

[0069] 50 Arm

[0070] 52 Arm shaft

[0071] 53 Arm driving motor

[0072] 61 Rotary cylinder

[0073] 62 Timing pulley

[0074] 63 Timing belt

[0075] 64 Timing pulley

[0076] 100 Film thickness measuring apparatus

[0077] 110 Sensor

[0078] 120 Controller

[0079] 122 Processor

[0080] 124 Memory

[0081] 126 Program

Examples

Embodiment Construction

[0029]In the following description, embodiments of the present invention will be explained with reference to the figures. In the figures which will be explained in the following description, a reference symbol assigned to one component is also assigned to the other component if the other component is the same as or corresponds to the one component, and overlapping explanation of these components will be omitted.

[0030]FIG. 1 is a schematic drawing which shows a construction of a polishing apparatus 10 according to an embodiment of the present invention. As shown in the figure, the polishing apparatus 10 comprises a polishing table 30 for holding a polishing pad 31, and a top ring 40 (a polishing head) for holding a substrate (a wafer) W, which is an object of polishing, in such a manner that the substrate faces the polishing pad 31, and pushing the substrate to a polishing surface of the polishing pad 31.

[0031]The polishing table 30 is connected, via a table shaft 32, to a table driv...

Claims

1. A polishing apparatus comprisinga polishing table which is provided with a sensor and constructed to be able to rotate,a polishing head which is arranged to face the polishing table, constructed to be able to rotate, and constructed to allow a substrate to be attached to a surface facing the polishing table, anda controller; whereinthe sensor is constructed to output, when the sensor passes a path on the substrate, time series data that comprises a series of pieces of measurement data relating to film thicknesses at multiple measurement points on the path, andthe controller is constructed toobtain the time series data from the sensor,apply interpolation using a first interpolation pitch to the measurement data in a first data range in the time series data,apply interpolation using a second interpolation pitch, that is different from the first interpolation pitch, to the measurement data in a second data range in the time series data, andcreate a film thickness profile corresponding to the path, based on the interpolated measurement data in the first data range and the second data range.

2. The polishing apparatus according to claim 1, wherein each of the interpolation using the first interpolation pitch and the interpolation using the second interpolation pitch includes a process for creating, based on the measurement data obtained at the multiple measurement points on the path, interpolation data for one or multiple interpolation points between the multiple measurement points on the path.

3. The polishing apparatus according to claim 2, wherein each of the first interpolation pitch and the second interpolation pitch represents a distance between the interpolation points or a distance between the interpolation point and the measurement point.

4. The polishing apparatus according to claim 1, whereinthe first data range corresponds to a part near an edge of the substrate,the second data range corresponds to a part on an inner side of the part near the edge of the substrate, andthe first interpolation pitch is narrower than the second interpolation pitch.

5. The polishing apparatus according to claim 4, wherein the controller is further constructed to accept a user input for designating the first data range and the second data range.

6. The polishing apparatus according to claim 1, wherein the controller is further constructed tojudge that successive pieces of measurement data corresponding to adjacent measurement points on the path, in the time series data, belong to the first data range, if a difference between the successive pieces of measurement data is larger than a predetermined value, andjudge that successive pieces of measurement data corresponding to adjacent measurement points on the path, in the time series data, belong to the second data range, if a difference between the successive pieces of measurement data is smaller than a predetermined value; whereinthe first interpolation pitch is narrower than the second interpolation pitch.

7. The polishing apparatus according to claim 1, wherein the controller is further constructed toobtain a reference profile with respect to film thickness relating to the path on the substrate,judge that pieces of measurement data in the time series data belong to the first data range, if each of deviations of the pieces of measurement data from related parts in the reference profile is larger than a predetermined value, andjudge that pieces of measurement data in the time series data belong to the second data range, if each of deviations of the pieces of measurement data from related parts in the reference profile is smaller than the predetermined value; whereinthe first interpolation pitch is narrower than the second interpolation pitch.

8. The polishing apparatus according to claim 7, wherein the reference profile is created in advance by using measurement data obtained from the sensor when multiple substrates were polished.

9. The polishing apparatus according to claim 1, wherein the controller is further constructed toobtain data representing a speed of rotation of the polishing table or a speed of rotation of the polishing head,judge that pieces of measurement data in the time series data belong to the first data range, if the speed of rotation when the pieces of measurement data are obtained is slower than a predetermined speed of rotation, andjudge that pieces of measurement data in the time series data belong to the second data range, if the speed of rotation when the pieces of measurement data are obtained is faster than the predetermined speed of rotation; whereinthe first interpolation pitch is narrower than the second interpolation pitch.

10. The polishing apparatus according to claim 9, wherein the data representing the speed of rotation is obtained from a rotation speed sensor, or is designated by a user input.

11. The polishing apparatus according to claim 1, wherein the controller is further constructed to display the created film thickness profile on a display.

12. A method for creating a film thickness profile in a polishing apparatus: whereinthe polishing apparatus comprisesa polishing table which is provided with a sensor and constructed to be able to rotate, anda polishing head which is arranged to face the polishing table, constructed to be able to rotate, and constructed to allow a substrate to be attached to a surface facing the polishing table; andthe method comprises steps foroutputting, by the sensor when the sensor passes a path on the substrate, time series data that comprises a series of pieces of measurement data relating to film thicknesses at multiple measurement points on the path,obtaining the time series data from the sensor,applying interpolation using a first interpolation pitch to the measurement data in a first data range in the time series data,applying interpolation using a second interpolation pitch, that is different from the first interpolation pitch, to the measurement data in a second data range in the time series data, andcreating a film thickness profile corresponding to the path, based on the interpolated measurement data in the first data range and the second data range.

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