Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B37/00—Lapping machines or devices; Accessories
  • B24B37/005—Control means for lapping machines or devices
  • B24B37/013—Devices or means for detecting lapping completion
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B37/00—Lapping machines or devices; Accessories
  • B24B37/27—Work carriers
  • B24B37/30—Work carriers for single side lapping of plane surfaces
  • B24B37/32—Retaining rings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B37/00—Lapping machines or devices; Accessories
  • B24B37/11—Lapping tools
  • B24B37/20—Lapping pads for working plane surfaces
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
  • B24B49/10—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving electrical means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
  • B24B49/16—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation taking regard of the load
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P52/00—Grinding, lapping or polishing of wafers, substrates or parts of devices

Definitions

• the present invention relates to a polishing apparatus and a polishing end point detection method for the polishing apparatus.
• a typical CMP apparatus includes a polishing table on which a polishing pad is attached, and a polishing head on which a substrate to be polished is attached.
• a substrate is polished by supplying a polishing liquid to a polishing pad and rotating at least one of a polishing table and a polishing head while the polishing pad and the substrate are in contact with each other.
• Patent Document 1 a current sensor measures the driving current supplied to the motor for rotating the polishing table or the like in order to detect the change in the polishing frictional force. Therefore, when noise is mixed in the measured signal, or due to an error caused by the accuracy of the current sensor itself, there is a possibility that the detection accuracy of the polishing end point is lowered.
• Patent Document 2 an analog current command value is output from a driver that supplies a drive current to the motor, and this is used to determine the polishing end point. etc. need to be processed.
• the analog signal from the driver before AD conversion is susceptible to noise, and by amplifying and rectifying the signal, the information (small changes in the signal) necessary for detecting the polishing end point is lost from the signal. It is possible. Furthermore, in both the configurations of Documents 1 and 2, it is difficult to synchronize the signals obtained from a plurality of motors (or drivers), so the polishing end point can be detected using a plurality of types of signals. I didn't.
• a polishing table for holding a polishing pad, a holder for holding an object to be polished so as to face the polishing pad, and a rotary drive for driving the polishing table.
• a motor for rotating the holder that holds the object to be polished, and a motor for swinging the holder that holds the object to be polished
• one or more drivers configured to supply a drive current to a motor, the driver configured to further output a digital signal responsive to the load of the at least one motor
• an end-point detection unit that detects a polishing end point indicating the end of polishing of the object to be polished, based on the digital signal.
• the digital signal corresponding to the load of the at least one motor is a signal indicating the rotation speed or the rotation angle of the at least one motor.
• the driver is configured to control the drive current based on the rotation speed or the rotation angle of the at least one motor.
• the digital signal corresponding to the motor load is a digital signal representing a command value for generating the drive current based on the rotation speed or rotation angle of the at least one motor.
• the digital signal corresponding to the load of the at least one motor includes a signal indicating a rotation speed or a rotation angle of the at least one motor, and a signal indicating the rotation speed or the rotation angle of the at least one motor.
• the end-point detection unit is configured to detect a polishing end point indicating the end of polishing of the object to be polished based on both of the digital signals. be.
• the end point detection section is configured to determine that the polishing end point has been reached when both of the digital signals show a predetermined change. be.
• Mode 6 the polishing apparatus according to any one of Modes 2 to 5 further comprises an encoder for detecting the rotation speed or rotation angle of the at least one motor.
• the end-point detection section detects the polishing object based on the plurality of digital signals output from the plurality of drivers. It is configured to detect a polishing endpoint indicating the end of polishing.
• Mode 8 in the polishing apparatus of Mode 7, the end point detection section reaches the polishing end point when each of the plurality of digital signals output from the plurality of drivers shows a predetermined change. It is configured to determine that
• Mode 9 there is provided a method for detecting a polishing end point indicating the end of polishing in a polishing apparatus, wherein the polishing apparatus includes a polishing table for holding a polishing pad and a polishing table facing the polishing pad. a holding part for holding the object to be polished, a motor for rotating the polishing table, a motor for rotating the holding part holding the object to be polished, and the a motor for swinging the holding part, one or more drivers, and an end point detection part, wherein the driver supplies a drive current to the at least one motor. , the driver further outputting a digital signal corresponding to the load of the at least one motor, and the end point detection unit performing the polishing based on the digital signal output from the driver detecting a polishing endpoint indicating the end of polishing of the object.
• FIG. 1 is a schematic diagram showing the overall configuration of a polishing apparatus according to one embodiment of the present invention
• FIG. 1 is a schematic diagram showing the overall configuration of a polishing apparatus according to one embodiment of the present invention
• FIG. 3 is a block diagram showing components related to motor control and polishing end point detection in the polishing apparatus according to one embodiment of the present invention
• 5 is a flowchart showing an example of polishing end point detection processing in the end point detection unit of the polishing apparatus according to one embodiment of the present invention
• 5 is a flowchart showing an example of polishing end point detection processing in the end point detection unit of the polishing apparatus according to one embodiment of the present invention
• 5 is a flowchart showing an example of polishing end point detection processing in the end point detection unit of the polishing apparatus according to one embodiment of the present invention
• the polishing apparatus 10 has a polishing table 30 for holding a polishing pad 31, and an object to be polished (for example, a substrate 100 such as a semiconductor wafer shown in FIG. 2) so as to face the polishing pad 31.
• a top ring 40 (holding portion) that presses the polishing surface of the polishing pad 31 against the surface of the polishing pad 31;
• a table driving motor 33 for rotating the polishing table 30;
• a top ring driving motor 43 for rotating the top ring 40;
• a driver 34 that supplies drive current to the drive motor 33 and a driver 44 that supplies drive current to the top ring drive motor 43 are provided.
• the polishing table 30 is connected via a table shaft 32 to a table driving motor 33 arranged below. Rotation of the table drive motor 33 allows the polishing table 30 to rotate around the axis of the table shaft 32 .
• a polishing pad 31 is attached to the upper surface of the polishing table 30 .
• a surface 311 of the polishing pad 31 constitutes a polishing surface for polishing the substrate 100 .
• a polishing liquid supply nozzle (not shown) is installed above the polishing table 30 , and polishing liquid is supplied from the polishing liquid supply nozzle to the polishing pad 31 on the polishing table 30 .
• the top ring 40 is supported by the arm 50 via the top ring shaft 42 .
• the top ring shaft 42 can be vertically moved with respect to the arm 50 by a vertically moving mechanism (not shown). The vertical movement of the top ring shaft 42 allows the top ring 40 to be elevated and positioned with respect to the arm 50 .
• the top ring 40 is configured to hold a substrate 100 such as a semiconductor wafer on its lower surface.
• the top ring 40 includes a retainer ring 41A that holds the outer peripheral edge of the substrate 100 to prevent the substrate 100 from jumping out of the top ring 40, and a polishing surface 311 that holds the substrate 100. and a top ring body 41B that presses against.
• a top ring drive motor 43 is fixed to the arm 50 that supports the top ring 40 .
• the top ring shaft 42 is connected to a rotating cylinder 61, and a timing pulley 62 provided on the outer periphery of this rotating cylinder 61 is connected to a top ring drive motor via a timing belt 63. It is connected to a timing pulley 64 provided at 43 .
• the rotating cylinder 61 and the top ring shaft 42 rotate integrally via the timing pulley 64, the timing belt 63, and the timing pulley 62, and the top ring 40 rotates the top ring shaft 42. rotate about the axis of
• the arm 50 is connected to an arm drive motor 53 fixed to an arm shaft 52 .
• a drive current is supplied from a driver 54 to the arm drive motor 53 .
• the arm drive motor 53 By driving the arm drive motor 53 , the arm 50 and the top ring 40 supported by the arm 50 can turn around the axis of the arm shaft 52 .
• the top ring 40 receives and holds the substrate 100 transported by a transport mechanism (transporter) (not shown) at a predetermined receiving position.
• the top ring 40 that has received the substrate 100 at the receiving position is moved above the polishing table 30 from the receiving position by the rotation of the arm 50 .
• the top ring shaft 42 and top ring 40 are lowered, and the substrate 100 is pressed against the polishing surface 311 of the polishing pad 31 .
• the table driving motor 33 and the top ring driving motor 43 are rotationally driven, the polishing table 30 and the top ring 40 are rotated, respectively.
• a polishing liquid is supplied thereon.
• the substrate 100 is brought into sliding contact with the polishing surface 311 of the polishing pad 31, and the surface of the substrate 100 is polished.
• the arm driving motor 53 periodically turns the arm 50 left and right, thereby swinging the top ring 40 with respect to the polishing pad 31 (that is, reciprocating on the polishing pad 31 ). ) polishing may be performed.
• the polishing apparatus 10 further indicates the end of polishing based on a control unit 20 for controlling each driver 34, 44, 54 and a signal indicating the state of polishing provided from each driver 34, 44, 54.
• An endpoint detector 25 configured to detect a polishing endpoint is provided.
• the substrate 100 (for example, a semiconductor wafer), which is the object to be polished, has a layered structure composed of a plurality of different materials such as semiconductors, conductors, and insulators, and different material layers have different coefficients of friction. Therefore, when polishing shifts from one layer of the laminated structure to another different material layer, a change occurs in the polishing frictional force when polishing the object to be polished.
• the polishing frictional force appears as a driving load of each motor 33, 43, 53 that rotates or swings the polishing table 30 or the top ring 40.
• FIG. Therefore, the current flowing through each motor 33, 43, 53 and the rotation speed of each motor 33, 43, 53 change according to the polishing frictional force, that is, according to the material of the surface being polished. , which can be used to detect the polishing endpoint.
• the polishing end point can be detected based on only one of the drive current and the rotation speed of each motor 33, 43, 53, or based on both.
• the control unit 20 and the end point detection unit 25 may be configured, for example, as a computer having a processor and memory.
• a program (software) containing one or more computer-executable instructions is stored in the memory, and the processor reads this program from the memory and executes it, thereby realizing each function of the control unit 20 and the endpoint detection unit 25. is performed.
• the end point detection unit 25 acquires a signal indicating the drive current of the motor and/or a signal indicating the state of rotation of the motor from each of the drivers 34, 44, 54, and calculates (data processes) these signals to perform polishing friction. It is operable to identify changes in force and detect polishing endpoints based on the identification results.
• FIG. 3 is a block diagram showing components related to motor control and polishing end point detection in the polishing apparatus 10.
• Each driver 34 , 44 , 54 includes a current command value generation section 102 , a current generation circuit 104 , a rotation speed acquisition section 106 and a signal output section 108 .
• Each driver 34, 44, 54 has the same configuration, and FIG. 3 shows only a system consisting of one driver and a motor connected to the driver, omitting the other two systems. Although the operation related to the driver 34 will be described below, the same applies to the drivers 44 and 54 as well.
• the control unit 20 outputs a rotation speed command value 202 for the table drive motor 33 to the driver 34 .
• the rotation speed command value 202 is data that indicates the rotation speed (also referred to as rotation speed) of the table drive motor 33, that is, the amount of rotation of the table drive motor 33 per unit time.
• An encoder 200 is attached to the table drive motor 33 .
• the encoder 200 is a sensor that detects the rotation of the table drive motor 33, and outputs a signal 208 corresponding to the number of rotations of the table drive motor 33 as it rotates.
• the encoder 200 may be configured to output a pulse signal each time the table drive motor 33 rotates by a predetermined angle (for example, eight times during one rotation).
• the rotational speed acquisition unit 106 obtains a measured value of the rotational speed of the table drive motor 33 based on the signal 208 from the encoder 200 (for example, by counting the number of pulse signals received per unit time). Data 210 indicating the measured value is output.
• the rotation speed command value data 202 from the control unit 20 and the rotation speed measurement value data 210 from the rotation speed acquisition unit 106 are input to the current command value generation unit 102 .
• the current command value generation unit 102 generates a current command value 204 of the drive current to be supplied to the table drive motor 33 based on the deviation between the rotation speed command value 202 and the rotation speed measurement value 210 .
• the current command value generation unit 102 adjusts the immediately preceding current command value 204 by an amount corresponding to the deviation between the rotation speed command value 202 and the rotation speed measurement value 210 to generate the next new current command value 204.
• the generated current command value data 204 is input to the current generation circuit 104 , and the current generation circuit 104 generates a drive current 206 for the table drive motor 33 according to this current command value 204 and supplies it to the table drive motor 33 .
• Current generator circuit 104 may be configured to generate drive current 206 by, for example, pulse width modulation (PWM) with a duty ratio responsive to current command value 204 .
• PWM pulse width modulation
• the signal output unit 108 acquires the current command value data 204 from the current command value generation unit 102, acquires the rotation speed measurement value data 210 from the rotation speed acquisition unit 106, and acquires these acquired data. data 204 and 210 to the control unit 20 .
• the current command value data 204 output from the current command value generation unit 102 and the rotation speed measurement value data 210 output from the rotation speed acquisition unit 106 are digital data. Therefore, the control unit 20 can obtain the current command value 204 and the rotational speed measurement value 210 from the driver 34 in the form of digital data.
• the current command value data 204 and the rotational speed measurement value data 210 from the driver 34 are temporarily stored in the data storage section 22 within the control section 20 .
• the data storage unit 22 may be a separate storage device provided outside the control unit 20 .
• the endpoint detection unit 25 extracts the current command value data 204 and/or the rotational speed measurement value data 210 from the data storage unit 22, and detects the polishing endpoint based on the extracted data.
• the current command value data 204 and the rotational speed measurement value data 210 are output from the driver 34 every 1 ms (milliseconds) and temporarily stored in the data storage unit 22, and the end point detection unit 25 detects data from the data storage unit 22 for a predetermined time.
• the polishing end point may be detected by collectively taking out data at intervals (for example, taking out data for 30 ms every 30 ms).
• a sampling period for outputting the current command value data 204 and the rotational speed measurement value data 210 from the driver 34 is preferably 1 ms or less. With a sampling period of 1 ms or less, continuous changes in the state (rotational speed and current) of the motor 33 can be reproduced with high accuracy, and changes included in the data 204 and 210 can be determined in the shortest possible time. Moreover, even when filtering such as moving average is used in combination, the time required to detect the end point can be shortened.
• the current command value data 204 used by the end point detection unit 25 to detect the polishing end point is data generated inside the driver 34 as a command value for the table drive motor 33.
• the end point of polishing can be detected without using a sensor for measuring the drive current 206 of .
• special processing for example, current command value and rotation speed measurement value data
• FIG. 4 is a flowchart showing an example of polishing end point detection processing in the end point detection unit 25 .
• the end point detection unit 25 retrieves the current command value data 204 or the rotational speed measurement value data 210 from the data storage unit 22 .
• the end point detection unit 25 calculates the amount of change over time in the current command value or the amount of change over time in the measured rotation speed value, and determines whether the absolute value of this amount of change is greater than a predetermined threshold. judge.
• the material of the surface to be polished of the object to be polished that is, the substrate 100
• the endpoint detection unit 25 determines that the polishing target object being polished has reached the polishing endpoint.
• the criteria for determining that the polishing end point has been reached are not limited to the above.
• the end point detection unit 25 may average the current command value and the rotational speed measurement value with respect to time, and then calculate the amount of change thereof. Further, in steps 404 and 406, the end point detection unit 25 calculates the differential value of the current command value and the rotational speed measurement value with respect to time, and determines that the polishing end point has been reached based on the change in the differential value. good too.
• the driver 34 may output data indicating the rotation angle of the motor 33 to the control unit 20 instead of the data 210 regarding the number of rotations (rotational speed) of the motor 33, and the end point detection unit 25 detects the rotation of the motor.
• the polishing end point may be determined based on angle data.
• Data indicating the rotation angle of the motor 33 can be obtained based on the reception time of the pulse signal output from the encoder 200, for example.
• the end point detection unit 25 determines in step 408 to end the polishing of the object being polished. Upon receiving the decision to end polishing, the polishing table 30 and the top ring 40 stop rotating, the top ring 40 rises from the polishing table 30, and the substrate 100 is removed from the top ring 40 and transferred to the next process (for example, a cleaning process). be On the other hand, if the polishing end point has not yet been reached, the end point detector 25 returns to step 402 to continue detection of the polishing end point, and repeats the steps from step 402 onward using new time data.
• FIG. 5 is a flowchart showing another example of polishing end point detection processing in the end point detection unit 25.
• the end point detector 25 determines the polishing end point based on both the current command value and the rotational speed measurement value.
• the end point detection unit 25 retrieves the current command value data 204 and the rotational speed measurement value data 210 from the data storage unit 22 .
• the end point detection unit 25 calculates the amount of change over time in the current command value, and determines whether or not the absolute value of this amount of change is greater than a predetermined first threshold. If the absolute value of the amount of change is greater than the first threshold, go to step 506; if the absolute value of the amount of change is less than the first threshold, go back to step 502; At step 506, the end point detection unit 25 further calculates the amount of change over time in the rotation speed measurement value, and determines whether or not the absolute value of this amount of change is greater than a predetermined second threshold. If the absolute value of the amount of change is greater than the second threshold, in step 508, the endpoint detector 25 determines that the polishing endpoint has been reached.
• the polishing end point can be detected more accurately by using both the current command value and the rotational speed measurement value as criteria for reaching the polishing end point. It is possible.
• special processing for example, current command value and rotation speed measurement value It is possible to detect the polishing end point using both the current command value data 204 and the rotational speed measurement value data 210 without performing the time adjustment process).
• FIG. 6 is a flowchart showing still another example of the polishing end point detection processing in the end point detection unit 25.
• the endpoint detector 25 determines the polishing endpoint based on data acquired from multiple drivers.
• step 602 the end point detection unit 25 obtains the current command value data and rotation speed measurement value data provided by the driver 34 (that is, regarding the table drive motor 33) from the data storage unit 22, and the data provided by the driver 44 (that is, Current command value data and rotational speed measurement value data relating to the top ring drive motor 43 are retrieved.
• step 604 the end point detection unit 25 calculates the amount of change over time in the current command value and/or the rotational speed measurement value relating to the table drive motor 33, and the absolute value of this amount of change is greater than a predetermined first threshold value. Determine whether it is larger.
• step 606 If the absolute value of the amount of change is greater than the first threshold, go to step 606; if the absolute value of the amount of change is less than the first threshold, go back to step 602; In step 606, the end point detection unit 25 further calculates the amount of change over time in the current command value and/or the rotational speed measurement value relating to the top ring drive motor 43, and the absolute value of this change amount reaches a predetermined second threshold value. Determines whether it is greater than If the absolute value of the amount of change is greater than the second threshold, in step 608, the endpoint detector 25 determines that the polishing endpoint has been reached.
• the polishing end point can be detected more accurately by using the data acquired from the plurality of drivers as the criterion for determining whether the polishing end point has been reached. be. Since the data from each driver is digital data and temporally synchronized, no special processing (for example, processing for matching the times of the data from one driver and the data from the other driver) can be performed. Polish endpoint detection can be performed using data from multiple drivers. Although only the data from the two drivers 34 and 44 are used in the flow chart of FIG. 6, it goes without saying that the data from the driver 54 may also be used to determine the polishing end point.
• polishing apparatus 20 control unit 22 data storage unit 25 end point detection unit 30 polishing table 31 polishing pad 311 polishing surface 32 table shaft 33 table drive motor 34 driver 40 top ring 41A retainer ring 41B top ring body 42 top ring shaft 43 top ring drive Motor 44 Driver 50 Arm 52 Arm shaft 53 Arm drive motor 54 Driver 61 Rotating cylinder 62 Timing pulley 63 Timing belt 64 Timing pulley 100 Board 102 Current command value generation unit 104 Current generation circuit 106 Rotation speed acquisition unit 108 Signal output unit 200 Encoder

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• Mechanical Treatment Of Semiconductor (AREA)
• Constituent Portions Of Griding Lathes, Driving, Sensing And Control (AREA)

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• 2022
  • 2022-02-25 JP JP2022028362A patent/JP2023124546A/ja active Pending
• 2023
  • 2023-01-05 US US18/840,195 patent/US20250178152A1/en active Pending
  • 2023-01-05 WO PCT/JP2023/000030 patent/WO2023162478A1/ja not_active Ceased

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