Polishing apparatus and method for controlling the polishing apparatus

Abstract

The polishing device is controlled so that dressing is performed at an appropriate timing. [Solution] The controller of the polishing apparatus determines the timing when the polishing ability of the polishing pad is predicted to fall below a threshold level based on the condition of the polishing surface of the polishing pad measured by a measuring device, identifies an available time slot immediately before the predicted timing from multiple available time slots in the operation schedule, and causes the dressing device to perform a dressing process on the polishing pad in the identified available time slot.

Description

[Technical Field]

[0001] The present invention relates to a polishing apparatus and a method for controlling the polishing apparatus. [Background technology]

[0002] When a substrate or other object to be polished is polished in a polishing apparatus, abrasive grains and polishing debris adhere to the surface of the polishing pad, causing the surface condition of the polishing pad to change and resulting in deterioration of polishing performance. To restore the surface condition of the polishing pad, a dressing process is performed on the polishing pad using a dressing apparatus. Conventionally, dressing has been performed every time a predetermined number of substrates have been polished (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-112194 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional dressing timing can reduce the throughput of the polishing apparatus due to dressing. Dressing can also cause excessive wear on the polishing pad. Therefore, it is necessary to control the polishing apparatus so that dressing is performed at the appropriate timing. [Means for solving the problem]

[0005] According to one embodiment, a polishing apparatus includes one or more polishing units, one or more functional units for pre-processing or post-processing of polishing, one or more transport units for transporting an object to be polished at least between the polishing unit and the functional unit, and a controller that controls the polishing units, the functional units, and the transport units to operate in accordance with a predetermined operation schedule in order to polish the object to be polished, the operation schedule including a plurality of free time slots in which the polishing units cannot perform processing due to operation constraints between the polishing units, the functional units, and the transport units, and each of the one or more polishing units The polishing apparatus includes a polishing pad configured to be pressed against an object to be polished when the object is polished, a measuring device for measuring the condition of the polishing surface of the polishing pad, and a dressing device configured to perform a dressing process on the polishing pad, wherein the controller is configured to determine a timing when the polishing ability of the polishing pad is predicted to fall below a threshold level based on the condition of the polishing surface of the polishing pad measured by the measuring device, identify an available time slot immediately before the predicted timing from the plurality of available time slots in the operation schedule, and cause the dressing device to perform a dressing process on the polishing pad in the identified available time slot.

[0006] According to one embodiment, a polishing apparatus includes one or more polishing units, one or more functional units for pre-processing or post-processing of polishing, one or more transport units for transporting an object to be polished at least between the polishing units and the functional units, and a controller for controlling the polishing units, the functional units, and the transport units to operate in accordance with a predetermined operation schedule in order to polish the object to be polished, the operation schedule including a process schedule for the polishing units to be processed according to operation constraints between the polishing units, the functional units, and the transport units. and a controller including a plurality of free time slots in which the one or more polishing units cannot perform the above-mentioned operation, wherein each of the one or more polishing units comprises a polishing pad configured to be pressed against the object to be polished when the object to be polished is polished, and a dressing device configured to perform a dressing process on the polishing pad, and the controller is configured to cause the dressing device to perform a dressing process on the polishing pad in each free time slot of the plurality of free time slots. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a plan view showing the overall configuration of a polishing apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a perspective view showing the configuration of a polishing unit according to an embodiment. [Figure 3] FIG. 3 is a side view schematically showing the polishing unit of FIG. 2. [Figure 4] 10 is a flowchart showing an example of a processing flow of a controller in the polishing apparatus. [Figure 5] 4 is an example of an operation schedule for controlling a polishing apparatus. [Figure 6] 10 is a graph showing an example of changes over time in a pad condition index value of a polishing pad in a specific polishing unit of a polishing apparatus. [Figure 7] 4 is a flowchart illustrating an exemplary control flow of a polishing apparatus according to an embodiment of the present invention. [Figure 8] 4 is an exemplary operation schedule for controlling a polishing apparatus used in the present embodiment. [Figure 9] 10 is a graph showing an example of the change over time in a pad condition index value for a specific polishing unit of a polishing apparatus in this embodiment. [Figure 10] 10 is a diagram showing an example of a change in wavelength composition ratio over time in a polishing unit when dressing is performed in an empty time slot TS303 by the control of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0009] FIG. 1 is a plan view showing the overall configuration of a polishing apparatus 10 according to one embodiment of the present invention. The polishing apparatus 10 may be, for example, a CMP (Chemical Mechanical Polishing) apparatus. CMP apparatuses are used to polish semiconductor substrates, glass substrates, or metal or semiconductor thin films formed on their surfaces. As shown in FIG. 1, the CMP apparatus (i.e., the polishing apparatus) 10 includes a load / unload unit 100, a first transfer unit 200, a second transfer unit 300, a third transfer unit 400, one or more polishing units 500, a wafer station 600, one or more cleaning units 700, and a controller 800.

[0010] The load / unload unit 100 is a module for loading and unloading substrates, which are objects to be polished, into and from the polishing apparatus 10. For example, a cassette (not shown), such as a FOUP, containing a large number of substrates before polishing, is loaded into the load / unload unit 100, and the substrates removed from the cassette are transported into the polishing apparatus 10. After polishing, the substrates are placed back into the cassette, and the cassette is removed from the polishing apparatus 10. In the example of FIG. 1, the polishing apparatus 10 includes four load / unload units 100, but the number of load / unload units 100 may be any number.

[0011] The first transport unit 200 is arranged adjacent to the load / unload unit 100 and the second transport unit 300, and is configured to remove substrates before polishing from a cassette mounted on the load / unload unit 100 and transfer them to the second transport unit 300, and to receive substrates after polishing from the second transport unit 300 and store them in the cassette of the load / unload unit 100.

[0012] The second transfer unit 300 is arranged adjacent to the first transfer unit 200, each polishing unit in the one or more polishing units 500, and the wafer station 600. As shown in FIG. 1 , the second transfer unit 300 may be arranged along the arrangement direction of the polishing units 500 arranged in one direction. The second transfer unit 300 is configured to receive an unpolished substrate from the first transfer unit 200, transport it to a predetermined polishing unit among the one or more polishing units 500, and store it in the polishing unit. The second transfer unit 300 is also configured to remove the substrate polished in the polishing unit 500 from the polishing unit 500, transport it to the wafer station 600, and hand it over to the wafer station 600.

[0013] The one or more polishing units 500 are units for polishing a substrate, which is an object to be polished, and will be described in detail later. In the example of Fig. 1, the polishing apparatus 10 includes four polishing units 500, but the number of polishing units 500 may be any number.

[0014] The wafer station 600 is a unit configured to temporarily hold a substrate polished in the polishing unit 500. The wafer station 600 may be configured as a part of the second transfer unit 300 or the third transfer unit 400.

[0015] The third transfer unit 400 is disposed adjacent to the wafer station 600 and each cleaning unit in the one or more cleaning units 700. As shown in FIG. 1 , the third transfer unit 400 may be disposed along the arrangement direction of the cleaning units 700, which are arranged side by side in one direction. The third transfer unit 400 is configured to transport a substrate temporarily held in the wafer station 600 to a predetermined cleaning unit among the one or more cleaning units 700 and store the substrate in the cleaning unit. The third transfer unit 400 is also configured to remove a substrate cleaned in the cleaning unit 700 from the cleaning unit 700 and return the substrate to the wafer station 600. The third transfer unit 400 may be disposed and configured to transfer the cleaned substrate to the first transfer unit 200 instead of returning it to the wafer station 600. Furthermore, the third transport unit 400 may be configured to remove a substrate that has been cleaned in one cleaning unit 700 from the cleaning unit 700 and then transport the substrate to another cleaning unit 700, for example, for cleaning to a higher degree of cleanliness.

[0016] The one or more cleaning units 700 are units that clean the polished substrate to wash away polishing liquid, polishing debris, and the like that adhere to the substrate surface during the polishing process in the polishing unit 500. Each cleaning unit of the one or more cleaning units 700 may be configured to operate using a different cleaning liquid or cleaning conditions, for example, to perform cleaning of a single substrate at different levels of cleanliness. Note that, although the polishing apparatus 10 in the example of FIG. 1 includes four cleaning units 700, any number of cleaning units 700 may be used.

[0017] The cleaning unit 700 is an example of a functional unit that performs post-processing on a substrate polished by the polishing unit 500 (i.e., cleaning is an example of post-processing). In addition to the cleaning unit 700, the polishing apparatus 10 may further include other functional units configured to perform other types of post-processing besides cleaning (e.g., a drying unit that dries the substrate after cleaning) and / or other functional units configured to perform predetermined pre-processing on the substrate before polishing (e.g., a pre-cleaning unit that cleans the substrate before polishing).

[0018] The controller 800 is a device for controlling the operation of each of the above elements in the polishing apparatus 10. The controller 800 can be configured by a general computer equipped with a processor and a memory. The memory stores a predetermined program for controlling the polishing apparatus 10. The processor reads and executes the program from the memory, thereby controlling each part of the polishing apparatus 10. The control by the controller 800 will be described in detail later.

[0019] Next, the polishing unit 500 included in the polishing apparatus 10 will be described in detail. FIG. 2 is a perspective view showing the configuration of the polishing unit 500 according to one embodiment. FIG. 3 is a side view schematically showing the polishing unit 500 shown in FIG. 2. When the polishing apparatus 10 includes multiple polishing units 500, each polishing unit 500 may have the same configuration as that shown in FIGS. 2 and 3. As shown in FIG. 2, the polishing unit 500 includes a polishing table 350 and a top ring 302 constituting a polishing head that holds a substrate, which is the object to be polished, and presses it against the polishing surface on the polishing table 350. The polishing table 350 is connected to a polishing table rotation motor (not shown) disposed below the polishing table 350 via a table shaft 351 and is rotatable about the table shaft 351. A polishing pad 352 is attached to the upper surface of the polishing table 350, and a surface 352a of the polishing pad 352 forms the polishing surface that polishes the substrate.

[0020] A polishing liquid supply nozzle 354 is installed above the polishing table 350, and this polishing liquid supply nozzle 354 supplies a polishing liquid onto a polishing pad 352 on the polishing table 350. Also, as shown in FIG. 2 , a passage 353 for supplying a polishing liquid is provided in the polishing table 350 and the table shaft 351. The passage 353 communicates with an opening 355 in the surface of the polishing table 350. A through-hole 357 is formed in the polishing pad 352 at a position corresponding to the opening 355 in the polishing table 350. The polishing liquid passing through the passage 353 is supplied to the surface of the polishing pad 352 through the opening 355 in the polishing table 350 and the through-hole 357 in the polishing pad 352. Note that the number of openings 355 in the polishing table 350 and the through-hole 357 in the polishing pad 352 may be one or more. Furthermore, the positions of the opening 355 in the polishing table 350 and the through-hole 357 in the polishing pad 352 are arbitrary, but in one embodiment, they are disposed near the center of the polishing table 350.

[0021] The top ring 302 is connected to a top ring shaft 18, which is movable up and down relative to a swing arm 360 by a vertical movement mechanism 319. The vertical movement of the top ring shaft 18 moves the entire top ring 302 up and down relative to the swing arm 360, thereby positioning it. The top ring shaft 18 is rotated by a top ring rotation motor (not shown). The rotation of the top ring shaft 18 causes the top ring 302 to rotate around the top ring shaft 18. A rotary joint 323 is attached to the upper end of the top ring shaft 18.

[0022] The top ring 302 is configured to hold a substrate, which is an object to be polished, on its underside. The swing arm 360 is configured to be rotatable about a support shaft 362. By rotating the swing arm 360, the top ring 302 can move between a substrate transfer position of a transport unit (not shown) (e.g., the second transport unit 300 described with reference to FIG. 1) and above the polishing table 350. By lowering the top ring shaft 18, the top ring 302 can be lowered to press the substrate against the surface (polishing surface) 352a of the polishing pad 352. At this time, the top ring 302 and the polishing table 350 are rotated, and a polishing liquid is supplied onto the polishing pad 352 from a polishing liquid supply nozzle 354 provided above the polishing table 350 and / or from an opening 355 provided in the polishing table 350. In this manner, the surface of the substrate can be polished by pressing the substrate against the polishing surface 352a of the polishing pad 352. During polishing of the substrate, the arm 360 may be fixed so that the top ring 302 covers the through-hole 357 of the polishing pad 352, or the arm 360 may be swung so that the top ring 302 passes through the center of the polishing pad 352.

[0023] The up-and-down movement mechanism 319 that moves the top ring shaft 18 and the top ring 302 up and down includes a bridge 28 that rotatably supports the top ring shaft 18 via a bearing 321, a ball screw 32 attached to the bridge 28, a support base 29 supported by a support column 130, and an AC servo motor 38 provided on the support base 29. The support base 29 that supports the servo motor 38 is fixed to a swing arm 360 via the support column 130.

[0024] The ball screw 32 includes a screw shaft 32a connected to a servo motor 38 and a nut 32b onto which the screw shaft 32a is threaded. The top ring shaft 18 moves up and down integrally with the bridge 28. Therefore, when the servo motor 38 is driven, the bridge 28 moves up and down via the ball screw 32, which in turn moves the top ring shaft 18 and the top ring 302 up and down.

[0025] A polishing unit 500 according to one embodiment includes a dressing unit 356 that dresses the polishing surface 352a of a polishing pad 352. The dressing unit 356 includes a dresser 50 that slides against the polishing surface 352a, a dresser shaft 51 to which the dresser 50 is connected, an air cylinder 53 attached to the upper end of the dresser shaft 51, and a swing arm 55 that rotatably supports the dresser shaft 51. The lower portion of the dresser 50 is formed by a dressing member 50a, and needle-shaped diamond particles are attached to the underside of the dressing member 50a. The air cylinder 53 is disposed on a support base 57 supported by struts 56, and the struts 56 are fixed to the swing arm 55.

[0026] The swing arm 55 is driven by a motor (not shown) and configured to rotate around a support shaft 58. The dresser shaft 51 is rotated by the drive of the motor (not shown), and the rotation of the dresser shaft 51 causes the dresser 50 to rotate around the dresser shaft 51. The air cylinder 53 moves the dresser 50 up and down via the dresser shaft 51, and presses the dresser 50 against the polishing surface 352a of the polishing pad 352 with a predetermined pressing force.

[0027] The polishing surface 352a of the polishing pad 352 is dressed as follows. The dresser 50 is pressed against the polishing surface 352a by the air cylinder 53, and simultaneously, pure water is supplied to the polishing surface 352a from a pure water supply nozzle (not shown). In this state, the dresser 50 rotates around the dresser shaft 51, causing the lower surface (diamond particles) of the dressing member 50a to slide against the rotating polishing surface 352a and swinging the swing arm 55 over the polishing surface 352a. In this way, the dresser 50 scrapes off the polishing pad 352, and the polishing surface 352a is dressed.

[0028] The polishing unit 500 according to one embodiment further includes a measurement unit 502 (not shown in FIG. 2 ) for measuring the condition of the polishing surface 352a of the polishing pad 352. For example, as shown in FIG. 3 , the measurement unit 502 is disposed above the polishing surface 352a of the polishing pad 352. The measurement unit 502 is configured, for example, to emit measurement light L1 toward the polishing pad 352 and detect reflected light L2 from the polishing surface 352a of the polishing pad 352. In one embodiment, the measurement unit 502 may be configured to provide a detection signal of the reflected light L2 to the controller 800. The controller 800 can identify the condition of the polishing surface 352a of the polishing pad 352 based on the detection signal of the reflected light L2 from the polishing pad 352 obtained from the measurement unit 502. For example, an index value indicating the condition of the polishing surface 352a of the polishing pad 352 (hereinafter referred to as a pad condition index value) may be calculated based on analyzing the intensity or spatial spectrum of the reflected light L2 from the polishing pad 352.

[0029] The pad condition index value can be calculated based on an appropriate analysis of the intensity or spatial spectrum of the reflected light L2 from the polishing pad 352. In one example, the "wavelength composition ratio" disclosed in Japanese Patent Application Laid-Open No. 2022-112194 may be used as the pad condition index value. Specifically, the wavelength composition ratio can be calculated from the measured reflected light L2 according to the following formula (1).

[0030]

number

[0031] Here, I(ξ) is the spatial spectral distribution of the reflected light L2 from the polishing pad 352, and ξ is the reciprocal of the spatial frequency of the reflected light L2. It is also assumed that ξ3<ξ1<ξ2<ξ4. The greater the roughness of the polishing surface 352a of the polishing pad 352 (i.e., the higher the polishing ability of the polishing pad 352), the smaller the wavelength composition ratio. Conversely, the smoother the polishing surface 352a of the polishing pad 352 (i.e., the lower the polishing ability of the polishing pad 352 due to wear of the polishing pad 352), the larger the wavelength composition ratio. Therefore, by knowing the value of the wavelength composition ratio, it is possible to understand the condition of the polishing surface 352a of the polishing pad 352 (or the polishing ability of the polishing pad 352).

[0032] Note that instead of the wavelength composition ratio as described above, another appropriate index may be used as the pad condition index value. Furthermore, although the above describes an embodiment in which the measuring unit 502 performs measurement using an optical method, the measuring unit 502 may be configured to perform measurement using another method, for example, an acoustic method. The measuring unit 502 may be configured to perform measurement using an optical method, an acoustic method, or another method and transmit the measurement signal or data to the controller 800. The controller 800 may be configured to calculate or determine a pad condition index value indicating the condition of the polishing surface 352a of the polishing pad 352 based on the measurement signal or data from the measuring unit 502. Alternatively, the measuring unit 502 itself (or the polishing unit 500) may be configured to have a computing function (e.g., a processor) that calculates the pad condition index value based on the measurement signal or data and provide the calculated pad condition index value to the controller 800.

[0033] 4 is a flowchart showing an example of a process flow of controller 800 in polishing apparatus 10. A series of operations performed by polishing apparatus 10 when polishing an object will be described with reference to FIG.

[0034] First, in step 402, the controller 800 creates an operation schedule based on predetermined recipe information for operating the transport units 200, 300, and 400, the polishing units 500, and the cleaning units 700 of the polishing apparatus 10 in an appropriate order. In the following step 404, the controller 800 controls the operation of each unit of the polishing apparatus 10 in accordance with the created operation schedule.

[0035] The predetermined recipe information for creating an operation schedule includes, for example, the number of substrates to be polished in the processing lot, the target polishing film thickness of the substrates to be polished, the material of the film to be polished, the expected polishing time per substrate, the number of polishing units 500 to be operated, the polishing operation conditions of each polishing unit 500 (for example, the rotation speed of each of the polishing table 350 and the top ring 302, the pressing force of the top ring 302 against the polishing table 350, the type of polishing liquid to be used, etc.), and amount, etc.), the number of cleaning units 700 to be operated, cleaning conditions in each cleaning unit 700 (for example, type of cleaning liquid, temperature, cleaning time, etc.), and the like.

[0036] FIG. 5 is an example of an operation schedule for controlling the polishing apparatus 10. Specifically, FIG. 5 shows an operation schedule for four substrates to be polished, from the Nth to the N+3th. The horizontal axis of FIG. 5 represents time, and the vertical axis of FIG. 5 corresponds to different substrates. In the example operation schedule of FIG. 5, for example, the Nth substrate to be polished (the bottom substrate in the figure) is transported by the first transport unit 200 from the load / unload unit 100 to the second transport unit 300 in time slot TS101, and is further transported by the second transport unit 300 to a predetermined polishing unit (referred to as polishing unit A) among one or more polishing units 500 in time slot TS102. Next, in time slot TS103, the polishing pad 352 is periodically dressed by the dressing unit 356. This periodic dressing may be determined, for example, based on the cumulative usage time of the polishing pad 352 in use.

[0037] Thereafter, in time slot TS104, polishing unit A polishes the Nth substrate to be polished. Here, when polishing of the Nth substrate to be polished is completed, the second transfer unit 300 is currently transferring the N+1th substrate to the wafer station 600 (see time slot TS204 for the N+1th substrate), so the Nth substrate to be polished remains in polishing unit A during the next time slot TS105. In time slot TS106, when the wafer station 600 becomes available, the second transfer unit 300 removes the Nth substrate to be polished from polishing unit A and transfers it to the wafer station 600, where it is temporarily held during time slot TS107.

[0038] Next, in time slot TS108, the Nth substrate to be polished is transferred by the third transfer unit 400 from the wafer station 600 to one cleaning unit (referred to as cleaning unit A) among the one or more cleaning units 700, and in time slot TS109, the Nth substrate to be polished is cleaned by cleaning unit A. Furthermore, in time slot TS110, the Nth substrate to be polished is transferred by the third transfer unit 400 from cleaning unit A to another cleaning unit B, and in time slot TS111, the Nth substrate to be polished is cleaned a second time by cleaning unit B. Thereafter, a similar process is performed in time slots TS112 and TS113, and the Nth substrate to be polished is cleaned a third time by cleaning unit C. Finally, in time slot TS114, the Nth substrate to be polished is returned by the first transfer unit 200 to the load / unload unit 100.

[0039] Similarly, for the N+1th substrate to be polished, operations of each part of the polishing apparatus 10 are performed in time slots TS201 to TS212. However, the polishing unit that polishes the N+1th substrate to be polished is polishing unit B, which is different from polishing unit A that polishes the Nth substrate to be polished (see time slot TS203). Note that the first transfer unit 200 can start transporting the N+1th substrate to be polished from the load / unload unit 100 after the first transfer unit 200 has handed over the previous substrate, the Nth substrate to the second transfer unit 300. Therefore, the start timing of time slot TS201, in which the first transfer unit 200 transports the N+1th substrate to be polished, is after the end timing of time slot TS101 (or TS102) for the Nth substrate to be polished.

[0040] Similarly, for the (N+2)th and (N+3)th substrates to be polished, the operations of the various parts of the polishing apparatus 10 are performed according to the respective time slots shown in Figure 5. However, the (N+2)th substrate is polished by polishing unit A, and the (N+3)th substrate is polished by polishing unit B. The polishing shall be performed at the respective times (see time slots TS304 and TS403).

[0041] Here, at the time of time slot TS302 when the (N+2)th substrate to be polished is transported to polishing unit A, polishing unit A is still processing the previous substrate (i.e., the Nth substrate). Therefore, this (N+2)th substrate to be polished is retained in the first transport unit 200 for the time slot TS303 that follows time slot TS302 (i.e., until polishing of the Nth substrate is completed in polishing unit A). This operation delay occurs because the timing of polishing unit A's processing of the Nth substrate is delayed due to the introduction of time slot TS103 for periodic dressing of the polishing pad 352 prior to polishing of the Nth substrate to be polished in polishing unit A. Furthermore, as a result of the (N+2)th substrate to be polished having to remain in the first transport unit 200 during time slot TS303, the start of time slot TS401 when the first transport unit 200 transports the next (N+3)th substrate from the load / unload unit 100 is postponed until the end of time slot TS303.

[0042] In this way, if the polishing pad 352 is dressed at regular intervals, delays may occur in the operation of certain units in the polishing apparatus 10, which may result in a decrease in the throughput (number of substrates processed per unit time) of the polishing apparatus 10. In addition, as will be explained below, it is expected that this may also hasten the wear of the polishing pad 352.

[0043] FIG. 6 is a graph showing an example of the change over time in the pad condition index value (e.g., wavelength composition ratio) of the polishing pad 352 in a specific polishing unit 500 (e.g., polishing unit A) of the polishing apparatus 10. The example operation schedule of FIG. 5 is also shown in FIG. 6 on the same time scale as the graph, and the change over time in the pad condition index value in FIG. 6 represents the change over time when the polishing apparatus 10 is operated according to the example operation schedule of FIG. 5. The graph of FIG. 6 also shows a dotted line 602 indicating the upper limit and a dotted line 604 indicating the lower limit of the appropriate range of the pad condition index value. As described above, the wavelength composition ratio increases as the polishing surface 352a of the polishing pad 352 is worn down through use, and decreases as the roughness of the polishing surface 352a is restored through dressing of the polishing pad 352. FIG. 6 shows the decrease in the wavelength composition ratio during time slot TS103, when the dressing unit 356 dresses the polishing pad 352. 6, however, at the start of time slot TS103, the value of the wavelength composition ratio is still below the upper limit of the appropriate range (dotted line 602) (i.e., polishing pad 352 still has sufficient polishing capacity), and it is possible to continue polishing the substrate without dressing polishing pad 352. In other words, the operation schedule in FIG. 5 is scheduled to dress polishing pad 352 earlier than necessary, which raises concerns that the number of dressings may increase and polishing pad 352 may reach the end of its life prematurely.

[0044] 7 is a flowchart showing an exemplary control flow of the polishing apparatus 10 according to one embodiment of the present invention, which allows the polishing apparatus 10 to operate more efficiently in the above respects. An example of the improved operation of the polishing apparatus 10 will be described with reference to FIG.

[0045] First, in step 702, controller 800 creates an operation schedule for operating each of transport units 200, 300, and 400, polishing units 500, and cleaning units 700 of polishing apparatus 10 in the appropriate order based on predetermined recipe information. However, unlike the operation schedule in Figure 5, this created operation schedule does not include a time slot for dressing polishing pad 352. In the following step 704, controller 800 begins controlling the operation of each unit of polishing apparatus 10 in accordance with the operation schedule created in step 702.

[0046] FIG. 8 shows an exemplary operation schedule for controlling the polishing apparatus 10, which is created and used in this embodiment. The operation schedule in FIG. 8 is written using the same legend as the operation schedule in FIG. 5. Therefore, to avoid complexity, a detailed description of the operation schedule in FIG. 8 will be omitted. However, it should be noted that the operation schedule in FIG. 8 includes several "free time slots." A free time slot refers to a time slot in which a specific polishing unit 500 cannot perform processing due to operational constraints between the units in the polishing apparatus 10 (e.g., the polishing unit 500, the cleaning unit 700, and the transport units 200, 300, and 400). For example, in the exemplary operation schedule in FIG. 8, the time slot TS303 for the (N+2)th substrate to be polished is a free time slot for the following reason: At the time of the time slot TS302 in which the (N+2)th substrate to be polished is transported to the polishing unit A, the polishing unit A is still processing the previous substrate, the (N)th substrate (similar to the example in FIG. 5). The Nth substrate is removed from polishing unit A by the second transport unit 300 in time slot TS105, and the second transport unit 300 is scheduled to transport the (N+3)th substrate to be polished in time slot TS402 prior to removing the Nth substrate from polishing unit A. Therefore, after time slot TS302, polishing of the Nth substrate in polishing unit A (time slot TS103) is completed, and the start of the polishing process for the (N+2)th substrate by polishing unit A (time slot TS304) is postponed until the second transport unit 300 transports the (N+3)th substrate in time slot TS402 and completes removing the Nth substrate from polishing unit A in time slot TS105. Thus, the exemplary operation schedule of FIG. 8 includes an empty time slot TS303 in which polishing unit A cannot perform any operation.

[0047] Returning to the flowchart, once operational control of polishing apparatus 10 is initiated, in step 706, controller 800 acquires, from the measuring unit 502 of each polishing unit 500, the condition of the polishing surface 352a of the polishing pad 352 in that polishing unit 500. For example, controller 800 acquires, from each measuring unit 502, a measurement signal indicating the condition of the polishing surface 352a of the polishing pad 352. In the following step 708, controller 800 calculates a pad condition index value for the polishing pad 352 of each polishing unit 500 based on the measurement signal acquired from each measuring unit 502. An exemplary manner of calculating the pad condition index value has been described above (see, for example, equation (1) for calculating the wavelength composition ratio).

[0048] Next, in step 710, the controller 800 tracks the change over time in the pad condition index value for each polishing unit 500 and predicts the timing when the pad condition index value will exceed a predetermined optimum range. As described above, as the polishing surface 352a of the polishing pad 352 is worn down due to use of the polishing pad 352, the value of the wavelength composition ratio increases. In other words, an increase in the value of the wavelength composition ratio corresponds to a decrease in the polishing ability of the polishing pad 352. For example, the controller 800 tracks the change over time in the value of the wavelength composition ratio for each polishing unit 500 and predicts the timing when the polishing ability of the polishing pad 352 will fall below a predetermined threshold level.

[0049] FIG. 9 is a graph showing an example of the change over time in the pad condition index value (e.g., wavelength composition ratio) for a specific polishing unit 500 (e.g., polishing unit A) of the polishing apparatus 10 in this embodiment. FIG. 9 also shows the example operation schedule of FIG. 8 on the same time scale as the graph. The upper and lower limits of the appropriate range of the pad condition index value are indicated by dotted lines 902 and 904, respectively. In FIG. 9, the value of the wavelength composition ratio increases over time (i.e., as the usage time of the polishing pad 352 increases). For example, at an appropriate time before the end of time slot TS302 for the (N+2)th substrate to be polished, the controller 800 determines the appropriate wavelength composition ratio for that time based on the change over time in the wavelength composition ratio up to that time. The value of the wavelength composition ratio at a later time is predicted (for example, by extrapolation), and the timing tx at which the predicted value of the wavelength composition ratio exceeds the upper limit value (dotted line 902) is identified.

[0050] Next, in step 712, the controller 800 searches the operation schedule for an available time slot located immediately before the timing identified by the prediction in step 710 (e.g., timing tx in FIG. 9 ) for each polishing unit 500. In the following step 714, the controller 800 designates the immediately preceding available time slot as a dressing execution slot and controls each polishing unit 500 to dress the polishing pad 352 in that dressing execution slot. For example, in the example of FIG. 9 , timing tx is identified (predicted) based on the wavelength composition ratio for polishing unit A as described above. The available time slot for polishing unit A located immediately before this timing tx is time slot TS303. Therefore, this available time slot TS303 is designated as the dressing execution unit for polishing unit A, and the dressing unit 356 of polishing unit A is controlled to dress the polishing pad 352 in the available time slot TS303. The timing of dressing in other polishing units 500 (for example, polishing unit B) is controlled in a similar manner.

[0051] 10 shows an example of the change over time in the wavelength composition ratio in polishing unit A when dressing is performed in the free time slot TS303 according to the above-described control. In the example of FIG. 10, dressing is performed after the pad condition index value (wavelength composition ratio) approaches the limit of the appropriate range, compared to the example of FIG. 6 described above. This allows the polishing capacity of polishing pad 352 to be utilized more effectively (i.e., right up to the point where the polishing capacity falls below a predetermined level). This prevents polishing pad 352 from being dressed earlier than necessary, thereby extending the life of polishing pad 352. Furthermore, in the control of this embodiment, dressing is performed using a "free time slot," so polishing pad 352 can be dressed without causing delays in the operation of other units in polishing apparatus 10. This effectively prevents a decrease in the throughput of polishing apparatus 10.

[0052] In another embodiment, the controller 800 may perform control so that the polishing pad 352 is dressed in any available time slot (e.g., all available time slots). In this case, the total number of dressings increases, but by setting the dressing time for each dressing to be short, excessive wear of the polishing pad 352 due to dressing can be prevented and the operation schedule of the entire polishing apparatus 10 can be made more efficient.

[0053] Although the embodiments of the present invention have been described above based on several examples, the above-described embodiments of the invention are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention naturally includes equivalents thereof. Furthermore, any combination or omission of the components described in the claims and specification is possible within the scope of solving at least part of the above-described problems or achieving at least part of the effects. [Explanation of symbols]

[0054] 10 Polishing equipment 100 Load / Unload Units 200 First transport unit 300 Second transport unit 400 Third transport unit 500 Polishing Unit 600 Wafer Station 700 Cleaning Unit 800 Controller 352 Polishing Pad 356 Dressing Unit 502 measurement unit

Claims

1. A polishing apparatus comprising: The polishing apparatus is one or more polishing units; one or more functional units for pre- or post-polishing treatment; one or more transport units for transporting objects to be polished at least between the polishing unit and the functional unit; a controller that controls the polishing unit, the functional unit, and the transport unit to operate in accordance with a predetermined operation schedule in order to polish the object to be polished, the operation schedule including a plurality of free time slots in which the polishing unit cannot perform processing due to operation constraints among the polishing unit, the functional unit, and the transport unit; each of the one or more polishing units comprises: a polishing pad configured to be pressed against the object to be polished when polishing the object; a measuring device for measuring the condition of the polishing surface of the polishing pad; a dressing device configured to dress the polishing pad; Equipped with The controller determining a timing when the polishing ability of the polishing pad is predicted to fall below a threshold level based on the state of the polishing surface of the polishing pad measured by the measuring device; identifying an available time slot immediately before the predicted timing from the plurality of available time slots in the operation schedule; causing the dressing device to perform a dressing process on the polishing pad in the identified free time slot; It is configured as follows: Polishing equipment.

2. 2. The polishing apparatus according to claim 1, wherein the timing is determined based on extrapolation of an index representing the state of the polishing surface of the polishing pad.

3. 2. The polishing apparatus of claim 1, wherein the controller is configured to predict by extrapolation whether the polishing capacity of the polishing pad will be below the threshold level for each of the plurality of free time slots in the operation schedule, and if predicted to be below the threshold level, to cause the dressing device to perform a dressing process on the polishing pad in that free time slot.

4. 4. The polishing apparatus according to claim 1, wherein the functional units include a cleaning unit for cleaning the object after polishing by the polishing unit.

5. The polishing apparatus of claim 1 , wherein the controller is further configured to create the predetermined operation schedule based on predetermined recipe information.

6. A polishing apparatus comprising: The polishing apparatus is one or more polishing units; one or more functional units for pre- or post-polishing treatment; one or more transport units for transporting objects to be polished at least between the polishing unit and the functional unit; a controller that controls the polishing unit, the functional unit, and the transport unit to operate in accordance with a predetermined operation schedule in order to polish the object to be polished, the operation schedule including a plurality of free time slots in which the polishing unit cannot perform processing due to operation constraints among the polishing unit, the functional unit, and the transport unit; each of the one or more polishing units comprises: a polishing pad configured to be pressed against the object to be polished when polishing the object; a dressing device configured to dress the polishing pad; Equipped with the controller is configured to cause the dressing device to perform a dressing process on the polishing pad in each of the plurality of free time slots. Polishing equipment.

7. A method for controlling a polishing apparatus, comprising: The polishing apparatus is one or more polishing units; one or more functional units for pre- or post-polishing treatment; one or more transport units for transporting objects to be polished at least between the polishing unit and the functional unit; a controller that controls the polishing unit, the functional unit, and the transport unit to operate in accordance with a predetermined operation schedule in order to polish the object to be polished, the operation schedule including a plurality of free time slots in which the polishing unit cannot perform processing due to operation constraints among the polishing unit, the functional unit, and the transport unit; each of the one or more polishing units comprises: a polishing pad configured to be pressed against the object to be polished when polishing the object; a measuring device for measuring the condition of the polishing surface of the polishing pad; a dressing device configured to dress the polishing pad; Equipped with The method comprises: determining, by the controller, when the polishing ability of the polishing pad is predicted to fall below a threshold level based on the state of the polishing surface of the polishing pad measured by the measurement device; identifying, by the controller, an available time slot immediately before the predicted timing from the plurality of available time slots in the operation schedule; causing the controller to cause the dressing device to perform a dressing process on the polishing pad in the identified free time slot; A method for controlling a polishing apparatus, comprising:

8. A method for controlling a polishing apparatus, comprising: The polishing apparatus is one or more polishing units; one or more functional units for pre- or post-polishing treatment; one or more transport units for transporting objects to be polished at least between the polishing unit and the functional unit; a controller that controls the polishing unit, the functional unit, and the transport unit to operate in accordance with a predetermined operation schedule in order to polish the object to be polished; a controller, wherein the operation schedule includes a plurality of free time slots in which the polishing unit cannot perform processing due to operation constraints between the polishing unit, the functional unit, and the transport unit; each of the one or more polishing units comprises: a polishing pad configured to be pressed against the object to be polished when polishing the object; a dressing device configured to dress the polishing pad; Equipped with The method for controlling a polishing apparatus includes a step of causing the controller to cause the dressing apparatus to perform a dressing process on the polishing pad in each of the plurality of free time slots.

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