POLISHING APPARATUS AND POLISHING METHOD FOR POLISHING A PERIPHERY OF A SUBSTRATE

CROSS REFERENCE TO RELATED APPLICATION

This document claims priority to Japanese Patent Application Number 2018-135649 filed Jul. 19, 2018, the entire contents of which are hereby incorporated by reference.

BACKGROUND

In a manufacturing process of a semiconductor device, various kinds of films are formed on a periphery of a wafer. Since these films may cause particles, the films need to be removed from the periphery. Therefore, a polishing apparatus, which includes a polishing tool such as a polishing tape, is used to polish the periphery of the wafer to remove the film from the periphery. The polishing apparatus is configured to press the polishing tool against the periphery of the wafer, while rotating the wafer about its axis, to thereby polish the periphery.

Polishing of the periphery of the wafer is terminated when the film is removed from the periphery. However, it is practically difficult to accurately detect a point of time at which the film is removed from the periphery. Thus, in a conventional technique, polishing of a periphery of a wafer is terminated when a preset time has elapsed. If a film residue exists on the polished periphery, an additional polishing is performed.

However, the time required for removing the film from the periphery of the wafer can vary depending on conditions of the film and the polishing tool, a portion of the wafer to be polished, and other factors. Therefore, the film may still exist on the wafer when the preset time has elapsed. If a polishing time is increased so as to prevent such insufficient polishing, a cost of consumables used for polishing one wafer is increased. Moreover, such an increase in the polishing time may result in excessive polishing of the periphery of the wafer.

SUMMARY OF THE INVENTION

According to embodiments, there are provided a polishing apparatus and a polishing method capable of accurately detecting a polishing end point of a periphery of a substrate, such as a wafer.

Embodiments, which will be described below, relate to an apparatus and a method for polishing a periphery of a substrate, such as a wafer, and more particularly to a technique for detecting a polishing end point of the periphery of the substrate.

In an embodiment, there is provided a polishing apparatus for polishing a periphery of a substrate, comprising: a substrate holder having a substrate holding surface for holding the substrate, the substrate holder being configured to rotate the substrate holding surface; a polishing head configured to press a polishing tool against the periphery of the substrate on the substrate holding surface; and an operation controller configured to control operations of the substrate holder and the polishing head, wherein the polishing head comprises: a pressing member configured to press the polishing tool against the periphery of the substrate; and a shear-force detection sensor configured to detect a shear force acting on the pressing member due to a frictional resistance between the polishing tool and the periphery of the substrate, the shear-force detection sensor being configured to output an index value indicating a magnitude of the shear force, and wherein the operation controller comprises a memory storing a program configured to determine a polishing end point at which the index value reaches a threshold value, and a processer configured to execute the program.

In an embodiment, the shear-force detection sensor comprises a tactile sensor including a sensor element having carbon microcoils, and the sensor element is fixed to the pressing member.

In an embodiment, the sensor element further has an elastic resin block, and the carbon microcoils are located in the elastic resin block.

In an embodiment, the polishing head has a polishing-tool pressing surface configured to support a back side of the polishing tool and to press the polishing tool against the periphery of the substrate. and at least a part of the polishing-tool pressing surface is constituted by the sensor element.

In an embodiment, the shear-force detection sensor comprises a load cell coupled to a back side of the pressing member.

In an embodiment, there is provided a polishing method of polishing a periphery of a substrate, comprising: holding the substrate on a substrate holding surface; rotating the substrate holding surface together with the substrate; polishing the periphery of the substrate by pressing a polishing tool with a pressing member of a polishing head against the periphery of the substrate; during polishing of the periphery of the substrate, detecting a shear force acting on the pressing member due to a frictional resistance between the polishing tool and the periphery of the substrate by a shear-force detection sensor; determining a polishing end point at which an index value indicating a magnitude of the shear force reaches a threshold value; and terminating polishing of the periphery of the substrate based on the polishing end point.

In an embodiment, the shear-force detection sensor comprises a tactile sensor including a sensor element having carbon microcoils, and the sensor element is fixed to the pressing member.

In an embodiment, the sensor element further has an elastic resin block, and the carbon microcoils are located in the elastic resin block.

In an embodiment, the polishing head has a polishing-tool pressing surface configured to support a back side of the polishing tool and to press the polishing tool against the periphery of the substrate, and at least a part of the polishing-tool pressing surface is constituted by the sensor element.

In an embodiment, the shear-force detection sensor comprises a load cell coupled to a back side of the pressing member.

When a film on the periphery of the substrate is removed by the polishing tool, an underlying layer is exposed. A frictional resistance between the film and the polishing tool is different from a frictional resistance between the underlying layer and the polishing tool. The frictional resistance acts as a shear force on the pressing member. When the underlying layer is exposed as a result of polishing of the substrate, the shear force changes. Therefore, the polishing end point can be accurately detected based on the change in the shear force.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B are enlarged cross-sectional views each showing a periphery of a substrate;

FIG. 2 is a schematic view showing a polishing apparatus for polishing a periphery of a wafer which is an example of a substrate;

FIG. 3 is a top view of the polishing apparatus shown in FIG. 2;

FIG. 4 is a view showing a polishing head which tilts up and down;

FIG. 5 is an enlarged view of the polishing head shown in FIG. 2;

FIG. 6 is a perspective view showing a shear-force detection sensor shown in

FIG. 5;

FIG. 7 is a perspective view showing another embodiment of the shear-force detection sensor;

FIG. 8 is a graph showing an index value of a shear force that fluctuates periodically;

FIG. 9 is a schematic view showing a configuration of an operation controller; and

FIG. 10 is a schematic view showing a computing system that can be used for setting an optimal polishing recipe.

DESCRIPTION OF EMBODIMENTS

Embodiments will now be described with reference to the drawings.

FIG. 1A and FIG. 1B are enlarged cross-sectional views each showing a periphery of a substrate. More specifically, FIG. 1A shows a cross-sectional view of a so-called straight-type substrate, and FIG. 1B shows a cross-sectional view of a so-called round-type substrate. Examples of the substrate include a wafer. The periphery of the substrate is defined as a region including a bevel portion, a top edge portion, and a bottom edge portion. In a wafer W shown in FIG. 1A, the bevel portion is an outermost circumferential surface of the wafer W (indicated by a symbol S) that is constituted by an upper slope (an upper bevel portion) P, a lower slope (a lower bevel portion) Q, and a side portion (an apex) R. In a wafer W shown in FIG. 1B, the bevel portion is a portion (indicated by a symbol S) having a curved cross section and forming an outermost circumferential surface of the wafer W. The top edge portion is an annular flat portion T1 located radially inwardly of the bevel portion S. The bottom edge portion is an annular flat portion T2 located opposite the top edge portion and located radially inwardly of the bevel portion S. The top edge portion T1 and the bottom edge portion T2 are connected to the bevel portion S. The top edge portion T1 may include a region where devices are formed.

FIG. 2 is a schematic view showing a polishing apparatus for polishing a periphery of a wafer which is an example of a substrate. The polishing apparatus includes a substrate holder 32 for holding and rotating a wafer W which is an example of a substrate, and a polishing head 34 for pressing a polishing tape 42, serving as a polishing tool, against a periphery of the wafer W held by the substrate holder 32. The substrate holder 32 includes a substrate holding surface 37 for holding the wafer W by a vacuum suction, a stage motor 39 for rotating the substrate holding surface 37, and an XY moving device 38 for translating the substrate holding surface 37 and the stage motor 39. The XY moving device 38 includes a combination of a ball screw mechanism and a servomotor (not shown) for moving the substrate holding surface 37 and the stage motor 39 in an X direction, and further includes a combination of a ball screw mechanism and a servomotor (not shown) for moving the substrate holding surface 37 and the stage motor 39 in a Y direction perpendicular to the X direction. The X direction and the Y direction are parallel to the substrate holding surface 37.

The wafer W, with its back surface facing downward, is placed on the substrate holding surface 37 by a transporting device (not shown). A groove 37a is formed in the substrate holding surface 37. The groove 37a communicates with a vacuum line 40. The vacuum line 40 is coupled to a non-illustrated vacuum source (e.g., vacuum pump). When a vacuum is created in the groove 37a of the substrate holding surface 37 through the vacuum line 40, the wafer W is held on the substrate holding surface 37 by the vacuum suction. In this state, the stage motor 39 rotates the substrate holding surface 37 to rotate the wafer W about its axis. A diameter of the substrate holding surface 37 is smaller than a diameter of the wafer W. A central region of the back surface of the wafer W is held by the substrate holding surface 37. The entire periphery of the wafer W protrudes outward from the substrate holding surface 37.

The polishing head 34 is disposed adjacent to the substrate holding surface 37. More specifically, the polishing head 34 is disposed so as to face the periphery of the wafer W held on the substrate holding surface 37. The polishing head 34 includes a plurality of guide rollers 43 for supporting the polishing tape 42 as a polishing tool, a pressing member (e.g., pressing pad) 44 for pressing the polishing tape 42 against the periphery of the wafer W, and an air cylinder 45 as an actuator for providing a pressing force to the pressing member 44.

The air cylinder 45 is coupled to the pressing member 44 and is configured to move the pressing member 44 toward the substrate holding surface 37. The air cylinder 45 exerts the pressing force on the pressing member 44, which in turn presses the polishing tape 42 against the periphery of the wafer W. Instead of the polishing tape, a whetstone may be used as the polishing tool.

The polishing head 34 is provided with a tape-advancing mechanism 50 for advancing the polishing tape 42. One end of the polishing tape 42 is connected to a feeding reel 51, and the other end is connected to a take-up reel 52. The tape-advancing mechanism 50 is configured to advance the polishing tape 42 at a predetermined speed from the feeding reel 51 to the take-up reel 52 via the polishing head 34. Examples of the polishing tape 42 to be used include a tape having abrasive grains fixed to a surface thereof, and a tape constituted by a hard nonwoven fabric.

Pure-water supply nozzles 57, 58 for supplying pure water onto the wafer W are arranged above and below the wafer W held on the substrate holding surface 37. The pure-water supply nozzle 57 is located above a center of the substrate holding surface 37. The pure water supplied onto an upper surface of the rotating wafer W spreads over the entire upper surface of the wafer W by a centrifugal force, thus covering the entire upper surface of the wafer W. Therefore, the pure water can prevent particles from adhering to the upper surface of the wafer W during polishing of the periphery of the wafer W. The pure-water supply nozzle 58 supplies the pure water onto a lower surface of the wafer W and forms a flow of the pure water in the radially outward direction. Flow-rate control valves 60, 61 are coupled to the pure-water supply nozzles 57, 58, respectively. These flow-rate control valves 60, 61 are configured to control flow rates of the pure water that flows through the pure-water supply nozzles 57, 58.

FIG. 3 is a top view of the polishing apparatus shown in FIG. 2. The polishing head 34 is held by a crank arm 55. More specifically, one end of the crank atm 55 is fixed to the polishing head 34, and the other end of the crank arm 55 is coupled to a servomotor 56. The crank arm 55 as a whole is parallel to the substrate holding surface 37. When the servomotor 56 rotates the crank arm 55 in a clockwise direction and a counterclockwise direction alternately by a predetermined angle, the entire polishing head 34 tilts upward and downward as shown in FIG. 4.

The periphery of the wafer W is polished as follows. The wafer W, held on the substrate holding surface 37, is rotated about the axis of the wafer W by the stage motor 39. The pure water is supplied from the pure-water supply nozzle 57 onto the upper surface of the rotating wafer W, and the pure water is supplied from the pure-water supply nozzle 58 onto the lower surface of the rotating wafer W. As shown in FIG. 4, the polishing head 34 tilts upward and downward while pressing the polishing tape 42 against the periphery of the wafer W. The polishing tape 42 is held in sliding contact with the periphery of the rotating wafer W in the presence of the pure water to thereby polish the periphery of the wafer W.

FIG. 5 is an enlarged view of the polishing head 34 shown in FIG. 2. As shown in FIG. 5, the polishing head 34 includes the pressing member 44 for pressing a polishing surface of the polishing tape 42 against the periphery of the wafer W, and the air cylinder 45 as an actuator for moving the pressing member 44 toward the substrate holding surface 37 of the substrate holder 32 (i.e., toward the periphery of the wafer W). The pressing member 44 and the air cylinder 45 are arranged at a back side of the polishing tape 42. The pressing force (i.e., a polishing load) applied to the wafer W is regulated by controlling a pressure of a gas supplied into the air cylinder 45.

The tape-advancing mechanism 50 for advancing the polishing tape 42 in a longitudinal direction of the polishing tape 42 is mounted to the polishing head 34. In this embodiment, the tape-advancing mechanism 50 is fixed to the polishing head 34. In one embodiment, the tape-advancing mechanism 50 may be provided at a location away from the polishing head 34.

The tape-advancing mechanism 50 includes a tape-advancing roller 50a, a nip roller 50b, and a motor 50c configured to rotate the tape-advancing roller 50a. The motor 50c is mounted to a side surface of the polishing head 34. The tape-advancing roller 50a is secured to a rotational shaft of the motor 50c. The nip roller 50b is adjacent to the tape-advancing roller 50a. The nip roller 50b is supported by a non-illustrated mechanism, which biases the nip roller 50b in a direction indicated by arrow NF in FIG. 5 (i.e., in a direction toward the tape-advancing roller 50a) so as to press the nip roller 50b against the tape-advancing roller 50a.

When the motor 50c rotates in a direction indicated by arrow in FIG. 5, the tape-advancing roller 50a is rotated to advance the polishing tape 42 from the feeding reel 51 to the take-up reel 52 via the polishing head 34. The nip roller 50b is configured to be rotatable about its own axis. During polishing of the wafer W, the tape-advancing mechanism 50 advances the polishing tape 42 in its longitudinal direction at a predetermined speed (e.g., several millimeters to several tens of millimeters per minute). The polishing head 34 includes the plurality of guide rollers 43. These guide rollers 43 each guide the polishing tape 42 such that the polishing tape 42 advances in a direction perpendicular to a tangential direction of the wafer W.

During polishing of the wafer W, a frictional resistance is generated between the polishing tape 42 and the periphery of the rotating wafer W. Since the pressing member 44 is held by the air cylinder 45, this frictional resistance acts as a lateral shear force on the pressing member 44. When the air cylinder 45 exerts a constant pressing force on the pressing member 44, the frictional resistance between the polishing tape 42 and the periphery of the wafer W may change depending on a material constituting the surface of the periphery of the wafer W. For example, when an oxide film constituting the surface of the periphery of the wafer W is removed by the polishing tape 42, a silicon layer which is an underlying layer is exposed. The exposure of the silicon layer results in a change in the frictional resistance. Therefore, a point of time at which the oxide film is removed can be determined from the change in the frictional resistance.

The polishing head 34 includes a shear-force detection sensor 70 for detecting a shear force acting on the pressing member 44 due to the frictional resistance between the polishing tape 42 and the periphery of the wafer W. The shear-force detection sensor 70 is a tactile sensor which includes a sensor element 71 having carbon microcoils (CMC). More specifically, the shear-force detection sensor 70 includes the sensor element 71 fixed to a front side of the pressing member 44, and an electric circuit 72 electrically connected to the sensor element 71.

The polishing head 34 has a polishing-tool pressing surface 46 for supporting the back side of the polishing tape 42 which is the polishing tool and for pressing the polishing tape 42 against the periphery of the wafer W. In this embodiment, the back side of the polishing tape 42 is supported by the sensor element 71, and the polishing tape 42 is pressed against the periphery of the wafer W by the sensor element 71. Therefore, the entire polishing-tool pressing surface 46 is constituted by the sensor element 71. In one embodiment, a part of the polishing-tool pressing surface 46 may be constituted by the sensor element 71, and the other part may be constituted by the pressing member 44. In another embodiment, the sensor element 71 may be embedded in the pressing member 44 or may be fixed to the back side of the pressing member 44. In this case, the polishing-tool pressing surface 46 is constituted by the pressing member 44.

FIG. 6 is a perspective view showing the shear-force detection sensor 70 shown in FIG. 5. The sensor element 71 has an elastic resin block 71a. The carbon microcoils (not shown) are located in the elastic resin block 71a. More specifically, the carbon microcoils are uniformly dispersed in the elastic resin block 71a. In one embodiment, the elastic resin block 71a is constituted by a silicone block.

During polishing of the wafer W, a shear force F acts on the pressing member 44 due to the frictional resistance between the polishing tape 42 and the periphery of the rotating wafer W. A direction of the shear force F coincides with a tangential direction of the wafer W at a contact point of the polishing tape 42 and the periphery of the wafer W, and is parallel to the substrate holding surface 37 and the polishing-tool pressing surface 46.

An electrical characteristic of the sensor element 71, in which the carbon microcoils are disposed, changes depending on an external force applied to the sensor element 71. Specifically, when the external force is applied to the sensor element 71, an impedance of the sensor element 71 changes. The electric circuit 72 applies an alternating voltage to the sensor element 71, detects the impedance of the sensor element 71, and outputs a numerical value that directly or indirectly indicates the impedance. This numerical value varies depending on a magnitude of the external force applied to the sensor element 71. Therefore, the shear-force detection sensor 70 is configured to output an index value comprising a numerical value that directly or indirectly indicates the magnitude of the shear force F.

During polishing of the periphery of the wafer W, the air cylinder 45 applies a constant pressing force E to the pressing member 44, so that the pressing member 44 presses the polishing tape 42 against the periphery of the wafer W with the constant pressing force E. At this time, the shear force F acts on the pressing member 44 and the sensor element 71 due to the frictional resistance between the polishing tape 42 and the periphery of the wafer W. The pressing force E and the shear force F are perpendicular to each other. The shear-force detection sensor 70 detects a combination force of the pressing force E and the shear force F. When the frictional resistance changes as a result of polishing of the periphery of the wafer W, the shear force F changes while the pressing force E remains constant. Therefore, the index value of the shear force F output from the shear-force detection sensor 70 changes with the change in the frictional resistance.

The sensor element 71 is integral with the pressing member 44 and is located just behind a polishing point (i.e., the contact point of the polishing tape 42 and the periphery of the wafer W). Therefore, the shear-force detection sensor 70 can directly detect the shear force F generated at the polishing point. In other words, the shear-force detection sensor 70 can rapidly and accurately detect a change in surface condition of the periphery of the wafer W.

As shown in FIG. 6, the electric circuit 72 of the shear-force detection sensor 70 is electrically connected to an operation controller 80. The index value of the shear force F output from the shear-force detection sensor 70 is sent in the form of a signal to the operation controller 80. The operation controller 80 is configured to determine a polishing end point at which the index value reaches a threshold value. More specifically, the operation controller 80 includes a memory 110 storing a program for determining the polishing end point at which the index value reaches the threshold value, and a processer 120 for executing the program. The operation controller 80 is constituted by a dedicated computer or a general-purpose computer.

The operation controller 80 terminates the polishing operation based on the polishing end point at which the index value reaches the threshold value. Specifically, the operation controller 80 instructs the polishing head 34 to stop its polishing operation, and instructs the stage motor 39 of the substrate holder 32 to stop its operation. As a result, polishing of the periphery of the wafer W is terminated.

FIG. 7 is a perspective view showing another embodiment of the shear-force detection sensor 70. Structures of this embodiment, which will not be specifically described, are the same as those of the embodiment shown in FIG. 6, and duplicate explanations will be omitted. In this embodiment, the shear-force detection force 70 includes a load cell 75 coupled to the back side of the pressing member 44. The electric circuit 72 shown in FIG. 6 is not provided. The load cell 75 is located between the air cylinder 45 and the pressing member 44. The load cell 75 is fixed to the back side of the pressing member 44, and is coupled to the air cylinder 45. In this embodiment, the polishing-tool pressing surface 46 is constituted by the pressing member 44.

The pressing force E generated by the air cylinder 45 is transmitted to the pressing member 44 through the load cell 75. In this embodiment, the load cell 75 comprises a biaxial load cell capable of separately detecting the pressing force E and the shear force F perpendicular to each other. In one embodiment, the load cell may be a uniaxial load cell capable of detecting only the shear force F.

The load cell 75 outputs an index value that directly or indirectly indicates the magnitude of the detected shear force F. The load cell 75 is electrically connected to the operation controller 80, so that the index value of the shear force F output from the shear-force detection sensor 70 is sent in the form of a signal to the operation controller 80. The operation controller 80 determines the polishing end point at which the index value reaches a threshold value.

According to this embodiment, the load cell 75 is located right behind the polishing point (i.e., the contact point of the polishing tape 42 and the periphery of the wafer W). Therefore, the load cell 75 can directly detect the shear force F. In other words, the shear-force detection sensor 70 can rapidly and accurately detect the change in surface condition of the periphery of the wafer W.

The shear-force detection sensors 70 shown in FIGS. 6 and 7 are each configured to output the index value of the shear force F which varies in accordance with the frictional resistance between the polishing tape 42 and the periphery of the rotating wafer W. If the center of the wafer W deviates from the center of the substrate holding surface 37, the index value of the shear force F periodically fluctuates, as shown in FIG. 8. Thus, the operation controller 80 is configured to detect a periodic change in the index value sent from the shear-force detection sensor 70, calculate an amount of eccentricity and a direction of eccentricity of the center of the wafer W from the center of the substrate holding surface 37 based on the detected periodic change, and operate the XY moving device 38, before a next wafer is polished, to move the substrate holding surface 37 in a direction as to eliminate the amount of eccentricity.

The amount of eccentricity can be calculated from an amplitude of the periodic change in the index value of the shear force F sent from the shear-force detection sensor 70. The direction of eccentricity can be calculated from a rotational angle of the substrate holding surface 37 corresponding to a peak of the index value that changes periodically. The rotational angle of the substrate holding surface 37 can be obtained from a rotary encoder (not shown) attached to the stage motor 39.

As described above, the XY moving device 38 is configured to move the substrate holding surface 37 and the stage motor 39 in the X direction and the Y direction which are perpendicular to each other. The operation controller 80 instructs the XY moving device 38 to move the substrate holding surface 37 and the stage motor 39 in a direction in which the calculated amount of eccentricity is eliminated. With such an operation, the next wafer is placed on the substrate holding surface 37 by a transporting device (not shown) such that the center of the next wafer coincides with the center of the substrate holding surface 37. As a result, uniform polishing of the periphery of the wafer is achieved.

The operation controller 80 is configured to control the operations of the polishing apparatus including the polishing head 34 and the substrate holder 32. The operation controller 80 in this embodiment is constituted by a dedicated computer or a general-purpose computer. FIG. 9 is a schematic view showing a configuration of the operation controller 80. The operation controller 80 includes the memory 110 in which a program and data are stored, the processer 120, such as CPU (central processing unit), for performing arithmetic operation according to instructions contained in the program stored in the memory 110, an input device 130 for inputting the data, the program, and various information into the memory 110, an output device 140 for outputting processing results and processed data, and a communication device 150 for connecting to a network, such as the Internet.

The memory 110 includes a main memory 111 which is accessible by the processer 120, and an auxiliary memory 112 that stores the data and the program therein. The main memory 111 may be a random-access memory (RAM), and the auxiliary memory 112 is a storage device which may be a hard disk drive (HDD) or a solid-state drive (SSD).

The input device 130 includes a keyboard and a mouse, and further includes a storage-medium reading device 132 for reading the data from a storage medium, and a storage-medium port 134 to which a storage medium can be connected. The storage medium is a non-transitory tangible computer-readable storage medium. Examples of the storage medium include optical disk (e.g., CD-ROM, DVD-ROM) and semiconductor memory (e.g., USB flash drive, memory card). Examples of the storage-medium reading device 132 include optical drive (e.g., CD drive, DVD drive) and memory reader. Examples of the storage-medium port 134 include USB port. The program and/or the data electrically stored in the storage medium is introduced into the operation controller 80 via the input device 130, and is stored in the auxiliary memory 112 of the memory 110. The output device 140 includes a display device 141 and a printer 142.

The operation controller 80 operates according to the instructions contained in the program electrically stored in the memory 110. Specifically, the operation controller 80 determines the polishing end point of the wafer W at which the index value, which indicates the magnitude of the shear force detected by the shear-force detection sensor 70, reaches the threshold value. The program is stored in a non-transitory tangible computer-readable storage medium, and the operation controller 80 is provided with the program via the storage medium. The operation controller 80 may be provided with the program via communication network, such as the Internet.

The polishing apparatus shown in FIG. 2 operates according to a polishing recipe stored in the operation controller 80. The polishing recipe comprises operation instructions that represent operating conditions (which are also referred to as polishing conditions) of the polishing apparatus when polishing a periphery of a wafer. In one example, the polishing recipe includes specific command values of the pressing force to be generated by the air cylinder 45, the rotational speed of the wafer, flow rates of pure water supplied from the pure-water supply nozzles 57, 58 onto the wafer, the advancing speed of the polishing tape 42, etc.

In one embodiment, a computing system that can be used for setting an optimal polishing recipe is provided. FIG. 10 is a schematic view showing the computing system. As shown in FIG. 10, the computing system includes a server 205 connected to polishing apparatuses 200, a plurality of polishing heads provided in each polishing apparatus 200, and a wafer-inspection device (substrate-inspection device) 201 by a network 202. The server 205 is constituted by a general-purpose computer or a dedicated computer. The server 205 may be installed in a factory where the polishing apparatuses 200 are disposed, or may be a so-called cloud server connected by the network 202 such as the Internet.

Each of the polishing apparatuses 200 is a polishing apparatus including a plurality of polishing heads 34, one of which is shown in FIG. 2. Specifically, each of the polishing apparatuses 200 is configured to press polishing tapes 42 against a periphery of a wafer by pressing members 44 to polish the periphery. In this embodiment, the wafer-inspection device (or substrate inspection device) 201 is a particle counter which is configured to count the number of particles present on a surface of the wafer (substrate).

The wafer polished by the polishing apparatus 200 is transported to the wafer-inspection device 201 by a transporting device (not shown). The wafer-inspection device 201 counts the number of particles on the surface of the wafer whose periphery has been polished, and sends the number of particles to the server 205 via the network 202. The polishing apparatus 200 sends polishing data to the server 205 via the network 202. The polishing data include the index value of the shear force output from the shear-force detection sensor 70 when the polishing apparatus 200 is polishing the wafer, the above-described command values (rotational speed of the wafer, etc.) contained in the polishing recipe, and information output from each sensor, motor, etc. Each time one or a predetermined number of wafers are polished, the wafer-inspection device 201 counts the number of particles on the polished wafer, and sends the number of particles to the server 205. Similarly, each time one or a predetermined number of wafers are polished, the polishing apparatus 200 sends the polishing data including the index value of the shear force and the command values contained in the polishing recipe to the server 205.

Each time the server 205 receives the number of particles and the polishing data, the server 205 stores learning data comprising a combination of the number of particles and the corresponding polishing data. The server 205 perfoiins machine learning using the learning data, and constructs a model for calculating a predicted number of particles from parameters including the index value of the shear force and the command values contained in the polishing recipe. Examples of machine learning include neural networks and deep learning. The learning data increases cumulatively as polishing of a wafer is performed. Therefore, the server 205 regularly or irregularly performs the machine learning using the learning data to update the model. A user can use the constructed model to search for parameters that can reduce the predicted number of particles.

In one embodiment, instead of the number of particles, the number of chips obtained from one wafer may be included in the learning data. In this case, the model is a model for calculating the predicted number of chips obtained from one wafer.

The previous description of embodiments is provided to enable a person skilled in the art to make and use the present invention. Moreover, various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles and specific examples defined herein may be applied to other embodiments. Therefore, the present invention is not intended to be limited to the embodiments described herein but is to be accorded the widest scope as defined by limitation of the claims.

POLISHING APPARATUS AND POLISHING METHOD FOR POLISHING A PERIPHERY OF A SUBSTRATE

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