Grinding device

Abstract

The present invention provides a polishing apparatus capable of preventing abrasive grains of a polishing liquid and abrasive scraps of a workpiece from adhering to an optical sensor head and improving measurement accuracy of a film thickness of the workpiece. A polishing device is provided with: a polishing table (3) that supports a polishing pad (2) in which a through-hole (4) is formed; a polishing head (1) that presses the workpiece (W) against the polishing pad (2); an optical film thickness measurement system (20) having an optical sensor head (25) disposed below the polishing pad (2); and a sensor head cleaning nozzle (40) that discharges a cleaning liquid toward the optical sensor head (25). The sensor head cleaning nozzle (40) is disposed within the polishing table (3) and faces the optical sensor head (25).

Description

Technical Field

[0001] The present invention relates to a technique for grinding workpieces such as wafers, wiring substrates, and square substrates, and more particularly to a technique for guiding light to the workpiece through a through hole of a grinding pad used for grinding the workpiece and measuring the film thickness of the workpiece based on the spectrum of reflected light from the workpiece. Background Art

[0002] In the manufacturing process of semiconductor devices, a chemical mechanical polishing (CMP) device is used to polish the surface of a workpiece such as a wafer. The CMP device has a polishing table with a polishing pad attached thereto and a polishing head for pressing the workpiece against the polishing surface of the polishing pad. The CMP device supplies a polishing liquid (e.g., slurry) to the polishing pad while pressing the workpiece against the polishing surface of the polishing pad using the polishing head, so that the surface of the workpiece and the polishing surface of the polishing pad are in sliding contact. The surface of the workpiece is polished by the chemical action of the polishing liquid and the mechanical action of the abrasive particles contained in the polishing liquid and / or the polishing pad.

[0003] The grinding of the workpiece is terminated when the thickness of the film (insulating film, silicon layer, etc.) constituting the surface of the workpiece reaches the target film thickness. The grinding device is equipped with an optical film thickness measurement system to measure the film thickness of the workpiece. The optical film thickness measurement system is configured to irradiate light to the workpiece using an optical sensor head arranged in the grinding table, receive reflected light from the workpiece, generate a spectrum of reflected light according to the intensity of the reflected light, and determine the film thickness of the workpiece based on the spectrum of the reflected light.

[0004] In order to stabilize the film thickness measurement by the optical film thickness measurement system, it is necessary to keep the light path clean. For example, Patent Document 1 describes that the entry of polishing liquid and polishing debris is restricted by filling the light path with a transparent liquid.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application No. 2006-525878

[0008] Technical problem to be solved by the invention

[0009] However, the abrasive particles contained in the polishing liquid and the grinding debris of the workpiece usually have a larger specific gravity than the transparent liquid, and the abrasive particles and grinding debris sometimes adhere to the optical sensor head. When the abrasive particles and grinding debris adhere to the optical sensor head, the measured value of the intensity of the reflected light from the workpiece decreases, and the optical film thickness measurement system cannot accurately measure the film thickness. Summary of the invention

[0010] Therefore, the present invention provides a polishing device that can prevent abrasive particles of a polishing liquid and polishing debris of a workpiece from adhering to an optical sensor head, thereby improving the measurement accuracy of a film thickness of the workpiece.

[0011] Technical solutions for solving technical problems

[0012] In one embodiment, a polishing device is provided, comprising: a polishing table supporting a polishing pad having a through hole formed therein; a polishing head pressing a workpiece against the polishing pad; an optical film thickness measuring system having an optical sensor head disposed below the polishing pad; and

[0013] A sensor head cleaning nozzle discharges a cleaning liquid toward the optical sensor head. The sensor head cleaning nozzle is disposed in the polishing table and faces the optical sensor head.

[0014] In one embodiment, the sensor head cleaning nozzle is arranged at a position higher than the optical sensor head.

[0015] In one embodiment, the sensor head cleaning nozzle is inclined downward with respect to a horizontal direction.

[0016] In one embodiment, the sensor head cleaning nozzle is arranged at the same height as the optical sensor head.

[0017] In one embodiment, the sensor head cleaning nozzle faces a horizontal direction.

[0018] In one embodiment, the polishing device further includes a transparent liquid inflow path for supplying the transparent liquid to the through hole, the optical sensor head is disposed in the transparent liquid inflow path, and the sensor head cleaning nozzle is in communication with the transparent liquid inflow path.

[0019] In one embodiment, the sensor head cleaning nozzle is a fan-shaped nozzle configured to form a fan-shaped jet flow of the cleaning liquid.

[0020] In one embodiment, the sensor head cleaning nozzle is a multi-nozzle having a plurality of cleaning liquid discharge ports arranged around the optical sensor head.

[0021] In one embodiment, the sensor head cleaning nozzle is connected to a cleaning liquid supply source, and the cleaning liquid supply source is a pure water supply source or a chemical liquid supply source.

[0022] In one embodiment, an ultrasonic vibrator is further provided for applying ultrasonic waves to the cleaning liquid supplied to the sensor head cleaning nozzle.

[0023] In one embodiment, the grinding device further comprises: a flow regulating valve connected to the sensor head cleaning nozzle; and an action control unit, which controls the action of the flow regulating valve, and the action control unit is configured to issue a command to the flow regulating valve to discharge the cleaning fluid from the sensor head cleaning nozzle at a first flow rate when the workpiece is above the optical sensor head during grinding of the workpiece, and to issue a command to the flow regulating valve to discharge the cleaning fluid from the sensor head cleaning nozzle at a second flow rate when the workpiece is not above the optical sensor head during grinding of the workpiece, and the second flow rate is greater than the first flow rate.

[0024] Effects of the Invention

[0025] The flow of cleaning liquid discharged from the sensor head cleaning nozzle toward the optical sensor head can prevent abrasive particles of the polishing liquid and grinding debris of the workpiece from adhering to the optical sensor head. Therefore, the optical film thickness measurement system can accurately measure the film thickness of the workpiece based on the intensity of the reflected light from the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram showing one embodiment of a polishing device.

[0027] Figure 2 It is a cross-sectional view showing the detailed structure of the optical film thickness measurement system.

[0028] Figure 3 This is an enlarged cross-sectional view showing one embodiment of an optical sensor head, a transparent liquid inflow path, a transparent liquid outflow path, and a sensor head cleaning nozzle.

[0029] Figure 4 It is an enlarged cross-sectional view showing another embodiment of the polishing device.

[0030] Figure 5 Observed from above Figure 3 or Figure 4 Diagram of a sensor head cleaning nozzle and optical sensor head of the illustrated embodiment.

[0031] Figure 6 FIG. 1 is a top view showing another implementation of liquid cleaning of the sensor head nozzle.

[0032] Figure 7 FIG. 1 is a top view showing another implementation of liquid cleaning of the sensor head nozzle.

[0033] Figure 8 This is an enlarged cross-sectional view showing still another embodiment of the polishing device.

[0034] Description of Reference Numerals

[0035] W Workpiece

[0036] 1 Grinding head

[0037] 2 Abrasive pad

[0038] 2a Grinding surface

[0039] 3 Grinding table

[0040] 4 Through holes

[0041] 5 Grinding fluid supply nozzle

[0042] 6. Workbench motor

[0043] 9 Motion Control Unit

[0044] 10 Head axis

[0045] 15 Grinding head rotating device

[0046] 20 Optical film thickness measurement system

[0047] 22 Light Source

[0048] 23. Beam splitter

[0049] 25 Optical sensor head

[0050] 27 Optical fiber cable for light projection

[0051] 28 Optical fiber cable for light reception

[0052] 30 Spectrum Processing Unit

[0053] 35 Transparent liquid supply line

[0054] 36 Transparent liquid discharge line

[0055] 41 Flow Control Valve

[0056] 50 Transparent liquid inflow path

[0057] 51 Transparent liquid outflow

[0058] 71 light projection surface

[0059] 72 light receiving surface

[0060] 81 Cleaning fluid outlet

[0061] 83 Cleaning fluid flow path

[0062] 85 Flow path structure

[0063] 87 Cleaning fluid inlet

[0064] 90 Ultrasonic vibrator. DETAILED DESCRIPTION

[0065] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 Schematic diagram showing one embodiment of a grinding device. Figure 1 As shown, the grinding device includes: a grinding pad 2 formed with a through hole 4, a grinding table 3 supporting the grinding pad 2, a grinding head 1 pressing the workpiece W against the grinding pad 2, a worktable motor 6 for rotating the grinding table 3, a grinding liquid supply nozzle 5 for supplying a grinding liquid such as slurry to the grinding pad 2, and an action control unit 9 for controlling the action of the grinding device.

[0066] The upper surface of the polishing pad 2 constitutes a polishing surface 2a for polishing the workpiece W. The through hole 4 penetrates the polishing pad 2. The workpiece W has a film constituting the surface of the workpiece W. Examples of the workpiece W to be polished include wafers, wiring substrates, and square substrates used in the manufacture of semiconductor devices.

[0067] The grinding head 1 is connected to the head shaft 10, and the head shaft 10 is connected to the grinding head rotating device 15. The grinding head rotating device 15 is configured to rotate the grinding head 1 together with the head shaft 10 in the direction indicated by the arrow. The structure of the grinding head rotating device 15 is not particularly limited. In one example, the grinding head rotating device 15 includes a motor, a belt, a pulley, etc. The grinding table 3 is connected to the workbench motor 6, and the workbench motor 6 is configured to rotate the grinding table 3 and the grinding pad 2 in the direction indicated by the arrow. The grinding head 1, the grinding head rotating device 15 and the workbench motor 6 are electrically connected to the action control unit 9.

[0068] The workpiece W is ground as follows. The table motor 6 and the grinding head rotating device 15 rotate the grinding table 3 and the grinding head 1. Figure 1 The polishing head 1 rotates in the direction indicated by the arrow, while supplying the polishing liquid from the polishing liquid supply nozzle 5 to the polishing surface 2a of the polishing pad 2 on the polishing table 3. The workpiece W is rotated by the polishing head 1, and the polishing head 1 presses the workpiece W against the polishing surface 2a of the polishing pad 2 in the state where the polishing liquid exists on the polishing pad 2. The surface of the workpiece W is polished by the chemical action of the polishing liquid and the mechanical action of the abrasive grains contained in the polishing liquid and / or the polishing pad 2.

[0069] The motion control unit 9 includes a storage device 9a for storing programs and a computing device 9b for performing operations according to the commands included in the programs. The motion control unit 9 is composed of at least one computer. The storage device 9a includes a main storage device such as a random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) and a solid state drive (SSD). Examples of the computing device 9b include a CPU (central processing unit) and a GPU (graphics processing unit). However, the specific structure of the motion control unit 9 is not limited to these examples.

[0070] The polishing device includes an optical film thickness measuring system 20 for measuring the film thickness of the workpiece W. The optical film thickness measuring system 20 includes a light source 22 that emits light, an optical sensor head 25 that irradiates the light of the light source 22 to the workpiece W and receives reflected light from the workpiece W, the optical sensor head 23 connected to the optical sensor head 25, a spectrometer 23, and a spectrum processing unit 30 that determines the film thickness of the workpiece W based on the spectrum of the reflected light from the workpiece W. The optical sensor head 25 is arranged in the polishing table 3 and rotates together with the polishing table 3.

[0071] The spectrum processing unit 30 includes a storage device 30a storing a program and a computing device 30b executing a calculation according to the command included in the program. The spectrum processing unit 30 is composed of at least one computer. The storage device 30a includes a main storage device such as a random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) and a solid state drive (SSD). Examples of the computing device 30b include a CPU (central processing unit) and a GPU (graphics processing unit). However, the specific structure of the spectrum processing unit 30 is not limited to these examples.

[0072] The motion control unit 9 and the spectrum processing unit 30 may also be composed of multiple computers. For example, the motion control unit 9 and the spectrum processing unit 30 may also be composed of a combination of an edge server and a cloud server. In one embodiment, the motion control unit 9 and the spectrum processing unit 30 may also be composed of one computer.

[0073] Figure 2 2 is a cross-sectional view showing the detailed structure of the optical film thickness measuring system 20. The optical sensor head 25 is arranged in the polishing table 3, and the light source 22 and the spectrometer 23 are installed on the polishing table 3. The optical sensor head 25, the light source 22 and the spectrometer 23 rotate integrally with the polishing table 3 and the polishing pad 2. The position of the optical sensor head 25 is a position that crosses the surface of the workpiece W on the polishing pad 2 every time the polishing table 3 and the polishing pad 2 rotate one circle. The optical sensor head 25 is connected to the light source 22 and the spectrometer 23, and the spectrometer 23 is connected to the spectrum processing unit 30.

[0074] The optical film thickness measuring device 20 includes a light-emitting optical fiber cable 27 for guiding light emitted from a light source 22 to the surface of a workpiece W, and a light-receiving optical fiber cable 28 for receiving light that receives reflected light from the workpiece W and transmits the reflected light to a spectrometer 23. The ends of the light-emitting optical fiber cable 27 and the light-receiving optical fiber cable 28 constitute an optical sensor head 25 for guiding light to the surface of the workpiece W and receiving reflected light from the workpiece W. The other end of the light-emitting optical fiber cable 27 is connected to the light source 22, and the other end of the light-receiving optical fiber cable 28 is connected to the spectrometer 23. The spectrometer 23 is configured to decompose the reflected light from the workpiece W according to wavelengths and measure the intensity of the reflected light within a predetermined wavelength range.

[0075] The optical sensor head 25, which is composed of the end of the optical fiber cable 27 for projecting light and the end of the optical fiber cable 28 for receiving light, is located below the through hole 4 of the polishing pad 2. The light emitted by the light source 22 is guided from the optical sensor head 25 to the workpiece W through the through hole 4 through the optical fiber cable 27 for projecting light. The reflected light from the workpiece W is received by the optical sensor head 25 through the through hole 4 and transmitted to the spectrometer 23 through the optical fiber cable 28 for receiving light. The spectrometer 23 generates the intensity measurement data of the reflected light by decomposing the reflected light according to the wavelength of the reflected light and measuring the intensity of the reflected light at each wavelength. The intensity measurement data of the reflected light is sent from the spectrometer 23 to the spectrum processing unit 30.

[0076] The spectrum processing unit 30 is configured to generate a spectrum of the reflected light from the workpiece W based on the reflected light intensity measurement data. The spectrum of the reflected light is represented as a line graph (i.e., a spectral waveform) showing the relationship between the wavelength and intensity of the reflected light. The intensity of the reflected light can also be represented as a relative value such as reflectivity or relative reflectivity.

[0077] The spectrum processing unit 30 is configured to determine the film thickness of the workpiece W based on the spectrum of the reflected light. A known method is used as a method for determining the film thickness of the workpiece W based on the spectrum. For example, the spectrum processing unit 30 determines a reference spectrum whose shape is closest to the spectrum of the reflected light from a reference spectrum library, and determines the film thickness associated with the determined reference spectrum. In other examples, the spectrum processing unit 30 performs Fourier transform on the spectrum of the reflected light, and determines the film thickness based on the obtained frequency spectrum.

[0078] The polishing device includes a sensor head cleaning nozzle 40 that discharges a cleaning liquid toward the optical sensor head 25 and cleans the optical sensor head 25 with the cleaning liquid. The sensor head cleaning nozzle 40 is arranged in the polishing table 3 and rotates integrally with the polishing table 3. The sensor head cleaning nozzle 40 is connected to a cleaning liquid supply line 52 extending in the polishing table 3, and the cleaning liquid supply line 52 is connected to a cleaning liquid supply source 54. The sensor head cleaning nozzle 40 is connected to the cleaning liquid supply source 54 via the cleaning liquid supply line 52. In one embodiment, the sensor head cleaning nozzle 40 and the cleaning liquid supply line 52 may also be integrally configured.

[0079] Examples of the cleaning liquid supply source 54 include a pure water supply source that supplies pure water as the cleaning liquid and a liquid supply source that supplies a liquid medicine as the cleaning liquid. Examples of the liquid medicine include a potassium hydroxide (KOH) solution having an etching effect. In the present embodiment, the cleaning liquid supply source 54 is a pure water supply source, and pure water is used as the cleaning liquid. However, the type of the cleaning liquid is not particularly limited as long as it can clean the optical sensor head 25.

[0080] The polishing device further includes a flow control valve 56 installed in the cleaning liquid supply line 52. The flow control valve 56 is electrically connected to the operation control unit 9, and the operation of the flow control valve 56 is controlled by the operation control unit 9. The flow control valve 56 is connected to the sensor head cleaning nozzle 40 via the cleaning liquid supply line 52. The flow control valve 56 is configured to adjust the flow rate of the cleaning liquid flowing in the cleaning liquid supply line 52. Therefore, the flow rate of the cleaning liquid discharged from the sensor head cleaning nozzle 40 toward the optical sensor head 25 is adjusted by the flow control valve 56.

[0081] The flow control valve 56 is an actuator driven type such as an electric valve, a solenoid valve or a pneumatic valve. The operation control unit 9 can issue a command to the flow control valve 56 to control the flow rate of the cleaning liquid discharged from the sensor head cleaning nozzle 40 toward the optical sensor head 25 .

[0082] The polishing table 3 has a transparent liquid inflow path 50 and a transparent liquid outflow path 51 which are communicated with the through hole 4. The transparent liquid inflow path 50 and the transparent liquid outflow path 51 are provided in the polishing table 3 and rotate integrally with the polishing table 3. The polishing device includes a transparent liquid supply line 35 connected to the transparent liquid inflow path 50, a transparent liquid discharge line 36 connected to the transparent liquid outflow path 51, and a flow rate regulating valve 41 connected to the transparent liquid supply line 35. The flow rate regulating valve 41 is configured to regulate the flow rate of the transparent liquid flowing in the transparent liquid supply line 35. Therefore, the flow rate of the transparent liquid supplied to the transparent liquid inflow path 50 and the through hole 4 is regulated by the flow rate regulating valve 41.

[0083] One end of the transparent liquid supply line 35 is connected to the transparent liquid inflow path 50, and the other end is connected to the transparent liquid supply source 55. The transparent liquid inflow path 50 may be integrally formed with the transparent liquid supply line 35. As an example of the transparent liquid supply source 55, a pure water supply source that supplies pure water as the transparent liquid may be cited. The transparent liquid (e.g., pure water) is supplied to the through hole 4 of the polishing pad 2 through the transparent liquid supply line 35 and the transparent liquid inflow path 50. The transparent liquid supplied to the through hole 4 of the polishing pad 2 is discharged from the through hole 4 through the transparent liquid outflow path 51, and further discharged through the transparent liquid discharge line 36. The transparent liquid outflow path 51 may be integrally formed with the transparent liquid discharge line 36.

[0084] The through-holes 4 of the polishing pad 2 are filled with the transparent liquid during polishing of the workpiece W. The flow of the transparent liquid in the through-holes 4 can restrict the intrusion of the polishing liquid and polishing debris of the workpiece W into the transparent liquid inflow path 50 .

[0085] The flow rate regulating valve 41 is an actuator driven type such as an electric valve, a solenoid valve, or a pneumatic valve. The operation control unit 9 can issue a command to the flow rate regulating valve 41 to control the flow rate of the transparent liquid supplied to the transparent liquid inflow path 50 .

[0086] During the polishing of the workpiece W, the polishing pad 2 rotates together with the polishing table 3, whereas the workpiece W held by the polishing head 1 does not rotate together with the polishing table 3. Therefore, there are times when the workpiece W is above the optical sensor head 25 and times when the workpiece W is not above the optical sensor head 25.

[0087] In one embodiment, when the workpiece W is above the optical sensor head 25, the motion control unit 9 issues a command to the flow control valve 41 to supply the transparent liquid to the transparent liquid inlet path 50 at a preset measurement flow rate, and when the workpiece W is not above the optical sensor head 25, the motion control unit 9 issues a command to the flow control valve 41 to supply the transparent liquid to the transparent liquid inlet path 50 at a flow rate lower than the measurement flow rate, or to stop supplying the transparent liquid to the transparent liquid inlet path 50. By such an operation, when the workpiece W is not above the optical sensor head 25, the polishing liquid on the polishing pad 2 can be prevented from being diluted by the transparent liquid (e.g., pure water).

[0088] Figure 3 FIG. 2 is an enlarged cross-sectional view showing an embodiment of the optical sensor head 25, the transparent liquid inflow path 50, the transparent liquid outflow path 51, and the sensor head cleaning nozzle 40. Figure 3 As shown, the optical sensor head 25 composed of the end 27a of the light-emitting optical fiber cable 27 and the end 28a of the light-receiving optical fiber cable 28 is located below the through hole 4 of the polishing pad 2. The optical sensor head 25 faces the through hole 4.

[0089] The optical sensor head 25 has a light-emitting surface 71 for emitting light and a light-receiving surface 72 for receiving reflected light from the workpiece W. In the present embodiment, the light-emitting surface 71 is formed by the front end surface of the light-emitting optical fiber cable 27, and the light-receiving surface 72 is formed by the front end surface of the light-receiving optical fiber cable 28. In one embodiment, the light-emitting surface 71 and the light-receiving surface 72 may be formed by optical elements such as lenses or glass attached to the ends 27a and 28a of the light-emitting optical fiber cable 27 and the light-receiving optical fiber cable 28.

[0090] The upper ends of the transparent liquid inflow path 50 and the transparent liquid outflow path 51 are open on the upper surface of the grinding table 3 and communicate with the through hole 4. The transparent liquid outflow path 51 is adjacent to the transparent liquid inflow path 50. The optical sensor head 25 is arranged in the transparent liquid inflow path 50. The light projection surface 71 of the optical sensor head 25 emits light toward the surface of the workpiece W and guides the light toward the surface of the workpiece W. The reflected light from the workpiece W travels toward the light receiving surface 72 of the optical sensor head 25 and is incident on the light receiving surface 72.

[0091] During the polishing of the workpiece W, the through hole 4 is filled with a transparent liquid (e.g., pure water). Light emitted from the optical sensor head 25, which is composed of the end 27a of the light-emitting optical fiber cable 27 and the end 28a of the light-receiving optical fiber cable 28, passes through the pure water filling the through hole 4 and is irradiated toward the workpiece W on the polishing pad 2. The reflected light from the workpiece W passes through the pure water filling the through hole 4 and is received by the optical sensor head 25.

[0092] The sensor head cleaning nozzle 40 is disposed in the polishing table 3, adjacent to the optical sensor head 25. The sensor head cleaning nozzle 40 is connected to the transparent liquid inflow path 50. Figure 3 As shown, the front end of the sensor head cleaning nozzle 40 may protrude into the transparent liquid inflow path 50. The relative positions of the sensor head cleaning nozzle 40 and the optical sensor head 25 are fixed, and the sensor head cleaning nozzle 40 and the optical sensor head 25 rotate integrally with the polishing table 3 and the polishing pad 2.

[0093] The sensor head cleaning nozzle 40 is configured to face the optical sensor head 25 and discharge the cleaning liquid toward the optical sensor head 25. More specifically, the sensor head cleaning nozzle 40 faces the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25 and cleans the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25 with the cleaning liquid. In the present embodiment, the sensor head cleaning nozzle 40 is arranged at a position higher than the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25. The sensor head cleaning nozzle 40 is inclined downward relative to the horizontal direction. Therefore, the sensor head cleaning nozzle 40 discharges the cleaning liquid obliquely downward toward the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25.

[0094] The flow of the cleaning liquid discharged from the sensor head cleaning nozzle 40 contacts the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25, and can prevent the abrasive particles contained in the polishing liquid and the polishing debris of the workpiece W from adhering to the light-projecting surface 71 and the light-receiving surface 72. Therefore, the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25 can be kept clean.

[0095] The light receiving surface 72 of the optical sensor head 25 receives the reflected light from the workpiece W. The optical film thickness measurement system 20 can accurately measure the film thickness of the workpiece W based on the intensity of the reflected light from the workpiece W.

[0096] During the grinding of the workpiece W, the flow rate regulating valve 56 is opened, and the cleaning liquid is supplied to the sensor head cleaning nozzle 40 through the cleaning liquid supply line 52 .

[0097] The flow regulating valve 56 is connected to the sensor head cleaning nozzle 40 via the cleaning liquid supply line 52. The flow regulating valve 56 can regulate the flow rate of the cleaning liquid discharged from the sensor head cleaning nozzle 40 toward the optical sensor head 25. The operation of the flow regulating valve 56 is controlled by the operation control unit 9. In one embodiment, during the grinding of the workpiece W, the flow rate of the cleaning liquid discharged from the sensor head cleaning nozzle 40 is maintained constant by the flow regulating valve 56.

[0098] In one embodiment, the operation control unit 9 is configured to issue a command to the flow control valve 41 to supply the transparent liquid to the transparent liquid inflow path 50 at a preset measurement flow rate when the workpiece W is located above the optical sensor head 25 during the grinding of the workpiece W, and to issue a command to the flow control valve 56 to discharge the cleaning liquid from the sensor head cleaning nozzle 40 at a first flow rate. The operation control unit 9 is configured to issue a command to the flow control valve 41 to supply the transparent liquid to the transparent liquid inflow path 50 at a flow rate lower than the measurement flow rate when the workpiece W is not located above the optical sensor head 25 during the grinding of the workpiece W, and to issue a command to the flow control valve 56 to discharge the cleaning liquid from the sensor head cleaning nozzle 40 at a second flow rate greater than the first flow rate. By such an operation, when the workpiece W is not located above the optical sensor head 25, a strong flow of the cleaning liquid is formed in the transparent liquid inflow path 50, and the cleaning liquid reaches the optical sensor head 25 without being blocked by the flow of the transparent liquid. Therefore, the cleaning effect of the cleaning liquid on the optical sensor head 25 can be improved.

[0099] In one embodiment, when the flow rate of the cleaning liquid is large enough to prevent the polishing liquid and polishing debris of the workpiece W from entering the transparent liquid inflow path 50 , the transparent liquid supply line 35 and the transparent liquid supply source 55 may be omitted.

[0100] In one embodiment, the cleaning of the optical sensor head 25 using the cleaning liquid may be performed before or after the grinding of the workpiece W. In this case, during the cleaning of the optical sensor head 25, the supply of the transparent liquid to the transparent liquid inflow path 50 and the through hole 4 is stopped. Figure 2 ), that is, when a chemical liquid is used as the cleaning liquid, the optical sensor head 25 can be cleaned during the polishing of the workpiece W under the condition that the chemical liquid is allowed to flow on the polishing pad 2. Under the condition that the chemical liquid is not preferably allowed to flow on the polishing pad 2, the optical sensor head 25 can be cleaned using the chemical liquid before or after the polishing of the workpiece W.

[0101] Figure 4 FIG. 1 is an enlarged cross-sectional view showing another embodiment of the grinding device. The structure and operation of this embodiment not specifically described are similar to those of the reference Figures 1 to 3 The described implementation modes are the same, so repeated descriptions thereof are omitted.

[0102] Figure 4 The embodiment shown is different from the embodiment shown in reference 1 in that the sensor head cleaning nozzle 40 faces the light projecting surface 71 and the light receiving surface 72 of the optical sensor head 25. Figures 1 to 3 The described embodiments are the same, but differ in that the sensor head cleaning nozzle 40 is arranged at the same height as the light projecting surface 71 and the light receiving surface 72 of the optical sensor head 25 and the sensor head cleaning nozzle 40 is oriented in the horizontal direction.

[0103] The flow of the cleaning liquid discharged from the sensor head cleaning nozzle 40 contacts the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25, and can prevent the abrasive particles contained in the polishing liquid and the polishing debris of the workpiece W from adhering to the light-projecting surface 71 and the light-receiving surface 72. Therefore, the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25 can be kept clean.

[0104] Figure 5 Observed from above Figure 3 or Figure 4 FIG. 4 is a diagram of the sensor head cleaning nozzle 40 and the optical sensor head 25 of the embodiment shown. Figure 5 As shown, the sensor head cleaning nozzle 40 is directed toward the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25. In one embodiment, as shown in FIG. Figure 6 As shown, the sensor head cleaning nozzle 40 may be a fan-shaped nozzle configured to form a fan-shaped jet flow of the cleaning liquid. The fan-shaped nozzle can flow the cleaning liquid to a wide area.

[0105] exist Figure 5 and Figure 6 In the illustrated embodiment, the sensor head cleaning nozzle 40 is arranged at a position closer to the light projecting surface 71 than to the light receiving surface 72 of the optical sensor head 25, but as long as the cleaning fluid discharged from the sensor head cleaning nozzle 40 can contact both the light projecting surface 71 and the light receiving surface 72, the relative position of the sensor head cleaning nozzle 40 with respect to the optical sensor head 25 is not particularly limited.

[0106] In one embodiment, if Figure 7 As shown, the sensor head cleaning nozzle 40 may be a multi-nozzle having a plurality of cleaning liquid discharge ports 81 arranged around the optical sensor head 25 . Figure 7The sensor head cleaning nozzle 40 of the illustrated embodiment includes a flow path structure 85 having a plurality of cleaning liquid discharge ports 81 and a cleaning liquid flow path 83. The flow path structure 85 extends around the optical sensor head 25. The cleaning liquid flow path 83 extends around the optical sensor head 25 and communicates with the plurality of cleaning liquid discharge ports 81.

[0107] The flow path structure 85 has a cleaning liquid inlet 87 communicating with the cleaning liquid flow path 83, and the cleaning liquid inlet 87 is connected to the cleaning liquid supply line 52. The cleaning liquid is supplied from the cleaning liquid supply line 52 to the cleaning liquid flow path 83 through the cleaning liquid inlet 87, and is discharged from the plurality of cleaning liquid discharge ports 81 toward the optical sensor head 25. When viewed from above, the plurality of cleaning liquid discharge ports 81 face inward in the radial direction of the transparent liquid inflow path 50.

[0108] The flow of the cleaning liquid discharged from the plurality of cleaning liquid discharge ports 81 contacts the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25, and can prevent the abrasive particles contained in the polishing liquid and the polishing debris of the workpiece W from adhering to the light-projecting surface 71 and the light-receiving surface 72. Therefore, the light-projecting surface 71 and the light-receiving surface 72 of the optical sensor head 25 can be kept clean.

[0109] Although not shown, another embodiment of the multi-nozzle having a plurality of cleaning liquid discharge ports 81 may be a multi-nozzle including a plurality of nozzles arranged around the optical sensor head 25 and having a plurality of cleaning liquid discharge ports 81 .

[0110] Reference Figure 6 as well as Figure 7 The described embodiment can also be applied to the embodiment described below.

[0111] Figure 8 FIG. 1 is an enlarged cross-sectional view showing another embodiment of the grinding device. The structure and operation of this embodiment not specifically described are similar to those of the reference Figures 1 to 3 The embodiments described are the same, so the repeated description thereof is omitted. In the present embodiment, the polishing device includes an ultrasonic vibrator 90 for applying ultrasonic waves to the cleaning liquid supplied to the sensor head cleaning nozzle 40. The ultrasonic vibrator 90 is disposed in the polishing table 3, adjacent to the sensor head cleaning nozzle 40. The ultrasonic vibrator 90 may also be mounted on the sensor head cleaning nozzle 40. In one embodiment, the ultrasonic vibrator 90 may also be mounted on the cleaning liquid supply line 52 connected to the sensor head cleaning nozzle 40.

[0112] According to the present embodiment, the cleaning liquid to which ultrasonic waves are applied by the ultrasonic transducer 90 is discharged from the sensor head cleaning nozzle 40 , and the light projecting surface 71 and the light receiving surface 72 of the optical sensor head 25 can be cleaned effectively.

[0113] Reference Figure 8The described embodiments can also be applied to Figures 4 to 7 Description of the embodiment.

[0114] The above-mentioned embodiments are recorded for the purpose of enabling a person with common knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above-mentioned embodiments can certainly be thought of by those skilled in the art, and the technical idea of ​​the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but should be interpreted as the widest scope of the technical idea defined by the scope of protection claimed by the present invention.

Claims

1. A grinding device, characterized in that: have: a grinding table supporting a grinding pad having a through hole formed therein; a grinding head, the grinding head pressing the workpiece against the grinding pad; an optical film thickness measuring system having an optical sensor head disposed below the polishing pad; as well as a sensor head cleaning nozzle that discharges cleaning fluid toward the optical sensor head, The sensor head cleaning nozzle is disposed in the grinding table and faces the optical sensor head.

2. The grinding device according to claim 1, characterized in that: The sensor head cleaning nozzle is arranged at a position higher than the optical sensor head.

3. The grinding device according to claim 2, characterized in that: The sensor head cleaning nozzle is inclined downward relative to the horizontal direction.

4. The grinding device according to claim 1, characterized in that: The sensor head cleaning nozzle is arranged at the same height as the optical sensor head.

5. The grinding device according to claim 4, characterized in that: The sensor head cleaning nozzle is oriented in a horizontal direction.

6. The grinding device according to claim 1, characterized in that: The polishing device further includes a transparent liquid inflow path for supplying the transparent liquid to the through hole. The optical sensor head is arranged in the transparent liquid inflow path. The sensor head cleaning nozzle is communicated with the transparent liquid inflow path.

7. The grinding device according to claim 1, characterized in that: The sensor head cleaning nozzle is a fan-shaped nozzle configured to form a fan-shaped jet flow of the cleaning liquid.

8. The grinding device according to claim 1, characterized in that: The sensor head cleaning nozzle is a multi-nozzle having a plurality of cleaning liquid discharge ports arranged around the optical sensor head.

9. The grinding device according to claim 1, characterized in that: The sensor head cleaning nozzle is connected to a cleaning liquid supply source, and the cleaning liquid supply source is a pure water supply source or a chemical liquid supply source.

10. The grinding device according to claim 1, characterized in that: The sensor head cleaning nozzle further includes an ultrasonic vibrator for applying ultrasonic waves to the cleaning liquid supplied to the sensor head cleaning nozzle.

11. The grinding device according to claim 1, characterized in that: Also available: a flow regulating valve connected to the sensor head cleaning nozzle; and an action control unit, the action control unit controls the action of the flow control valve, The action control unit is configured to issue a command to the flow regulating valve to discharge the cleaning fluid from the sensor head cleaning nozzle at a first flow rate when the workpiece is above the optical sensor head during grinding of the workpiece, and to issue a command to the flow regulating valve to discharge the cleaning fluid from the sensor head cleaning nozzle at a second flow rate when the workpiece is not above the optical sensor head during grinding of the workpiece, and the second flow rate is greater than the first flow rate.

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