Grinding device

Abstract

To notify a worker of adhesion of polishing liquid or cleaning liquid to outside of a processing chamber, in order to call attention.SOLUTION: A polishing device 1 is provided with: a chuck table 10 that holds a wafer W using a holding surface; a polishing mechanism 20 that polishes the wafer W using a polishing pad 25; a processing chamber S storing the chuck table 10 and the polishing mechanism 20; and a polishing liquid supply unit 40 that supplies acidic or alkaline polishing liquid to the polishing pad 25 in the processing chamber S, and the polishing device polishes the wafer W. A coating-material seal 2 coated with coating materials whose colors turn when the polishing liquid is adhered thereto is made to adhere to the outside of the processing chamber S. The device is provided with a color sensor (a color sensing part) 60 that receives light reflected on the coating-material seal 2 to sense the color of the light, a determining part 70 that determines adhesion of the acidic liquid or alkaline liquid on the basis of the sensed color by the color sensor 60, and a display lamp (a notification part) 80 that notifies a worker of the adhesion on the basis of the determination by the determining part 70, for instance.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polishing apparatus for polishing a wafer held on a chuck table.

Background Art

[0002] In the manufacturing process of semiconductor devices such as ICs and LSIs, in order to miniaturize and lighten the semiconductor devices, the back surface of the wafer is ground and the wafer is thinned to a predetermined thickness. This grinding of the wafer is performed by pressing a grinding wheel against the back surface (upper surface in the processing state) of the wafer while rotating the grinding wheel at high speed. When the back surface of the wafer is ground by such a grinding method, grinding marks remain on the back surface (grinding surface) of the wafer, and these grinding marks cause a decrease in the flexural strength of the wafer.

[0003] Therefore, the back surface (grinding surface) of the wafer is polished by a polishing pad of a polishing apparatus to remove the grinding marks. Here, as a polishing apparatus, there is known one that polishes a wafer while supplying a polishing liquid (slurry) to the contact portion (polishing processing portion) between the polishing pad and the wafer (see, for example, Patent Documents 1 to 3).

[0004] In addition, a cleaning liquid is supplied to the polished wafer to clean the wafer. However, in order to neutralize the polishing liquid, when the polishing liquid is alkaline, the wafer is cleaned with an acidic cleaning liquid, and when the polishing liquid is acidic, the wafer is cleaned with an alkaline cleaning liquid.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

[0006] The polishing fluids used to polish wafers and the cleaning fluids used to clean them are alkaline or acidic and transparent. Therefore, even if these polishing or cleaning fluids adhere to the outside of the processing room, for example, the outer surface of the processing room, workers may not easily notice them, and there is a possibility that workers may inadvertently come into contact with harmful polishing or cleaning fluids.

[0007] The present invention has been made in view of the above problems, and its purpose is to provide a polishing apparatus that can notify the operator and draw their attention to the fact that polishing fluid or cleaning fluid is adhering to the outside of the processing chamber. [Means for solving the problem]

[0008] The invention that solves the above problems is a polishing apparatus for polishing wafers, comprising a chuck table for holding a wafer on a holding surface, a polishing mechanism for polishing the wafer with a polishing pad, a processing chamber housing the chuck table and the polishing mechanism, and a polishing liquid supply unit for supplying an acidic or alkaline polishing liquid to the polishing pad in the processing chamber, wherein the processing chamber is located outside surface The paint that discolors when the polishing liquid comes into contact with it Application It is characterized by doing so. [Effects of the Invention]

[0009] According to the present invention, the discoloration of paint placed outside the processing chamber can alert the worker that polishing fluid has adhered to the outside of the processing chamber, thereby drawing their attention to the situation. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing a part of the polishing apparatus according to the present invention, broken off. [Figure 2] This is an exploded perspective view of the polishing fluid supply unit and the cleaning fluid supply unit of the polishing apparatus according to the present invention. [Figure 3] This is a perspective view of the polishing fluid supply unit and the cleaning fluid supply unit of the polishing apparatus according to the present invention. [Figure 4] This is a block diagram showing the configuration of a detection system for detecting the presence or absence of polishing liquid or cleaning liquid in a polishing apparatus according to the present invention. [Figure 5] This flowchart shows the processing procedure of a detection system for detecting the presence or absence of polishing liquid or cleaning liquid in a polishing apparatus according to the present invention. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the accompanying drawings.

[0012] [Configuration of the polishing device] First, the configuration of the polishing apparatus 1 according to the present invention will be described. In the following description, the directions indicated by arrows in Figure 1 will be the X-axis direction (left and right direction), the Y-axis direction (front and back direction), and the Z-axis direction (up and down direction), respectively.

[0013] The polishing apparatus 1 shown in Figure 1 is a device for polishing a thin, disc-shaped wafer W, which is the object to be polished, and its main components include a chuck table 10 for holding the wafer W, a polishing mechanism 20 for polishing the wafer W held on the chuck table 10, a processing chamber S that houses the polishing mechanism 20 and the chuck table 10, a polishing liquid supply unit 40 for supplying polishing liquid to the polishing mechanism 20, a cleaning liquid supply unit 50 for supplying cleaning liquid to the wafer W after polishing, a color sensor 60 which is a color detection unit that receives reflected light reflected by a paint seal 2 (see Figure 4) attached to the outer surface of the processing chamber S and detects the color of the paint seal 2, a determination unit 70 (see Figure 4) which determines whether the polishing liquid or cleaning liquid attached to the paint seal 2 is acidic or alkaline based on the color detected by the color sensor 60, and an indicator light 80 which is a notification unit that notifies the operator when the determination unit 70 determines that polishing liquid or cleaning liquid is attached to the outer surface of the processing chamber S.

[0014] Here, the wafer W is composed of a single-crystal silicon base material. On the surface facing downward in the state shown in FIG. 1, a plurality of devices (not shown) are formed, and these devices are protected by a protective tape (not shown) adhered to the surface of the wafer W. Then, the wafer W is held by the chuck table 10 with its surface (the lower surface in FIG. 1), and the back surface (the upper surface in FIG. 1) is polished by the polishing mechanism 20.

[0015] Next, the chuck table 10, which is a main component constituting the grinding device 1, the polishing mechanism 20, the processing chamber S, the polishing liquid supply unit 40 and the cleaning liquid supply unit 50, the color sensor 60 constituting the color detection unit, and the configurations of the determination unit 70 and the indicator lamp 80 will be sequentially described below.

[0016] (Chuck Table) The chuck table 10 is a disk-shaped member, and a disk-shaped porous member 10A is incorporated in the upper central portion thereof. Here, the porous member 10A is composed of porous ceramic or the like, and its upper surface constitutes a holding surface for sucking and holding the disk-shaped wafer W. The porous member 10A is selectively connected to a suction source (not shown) such as a vacuum pump.

[0017] Then, the chuck table 10 is rotationally driven at a predetermined speed about a vertical central axis by the rotational drive mechanism 12 rotationally driving the vertical rotary shaft 11 disposed below it. Here, the rotational drive mechanism 12 is composed of an electric motor 13 as a drive source, a small-diameter drive pulley 14 attached to the upper end of an output shaft (motor shaft) (not shown) extending vertically upward from the electric motor 13, a large-diameter driven pulley 15 attached to the rotary shaft 11, and an endless timing belt 16 wound around the drive pulley 14 and the driven pulley 15.

[0018] Incidentally, as shown in FIG. 1, the polishing apparatus 1 according to the present embodiment includes a rectangular box-shaped base 100 that is long in the Y-axis direction (front-rear direction). Inside this base 100, a rectangular block-shaped inner base 101 is accommodated. And on this inner base 101, a horizontal movement mechanism 3 for moving the chuck table 10 and the wafer W sucked and held thereon along the Y-axis direction (front-rear direction) is provided. This horizontal movement mechanism 3 includes a block-shaped slider 4, and this slider 4 is slidable in the Y-axis direction along a pair of left and right guide rails 5 arranged parallel to each other along the Y-axis direction (front-rear direction). Therefore, the chuck table 10 and the rotation drive mechanism 12 supported by this slider 4 are slidable along the Y-axis direction together with the slider 4.

[0019] And between the pair of left and right guide rails 5 on the inner base 101, a rotatable ball screw shaft 6 extending in the Y-axis direction (front-rear direction) is disposed. One end of the ball screw shaft 6 in the Y-axis direction (the left end in FIG. 1) is connected to an electric motor 7 that can be reversely rotated, which is a drive source. Also, the other end of the ball screw shaft 6 in the Y-axis direction (the right end in FIG. 1) is rotatably supported by the inner base 101 by a bearing 8 erected on the inner base 101. Note that a nut member (not shown) protruding downward from the slider 4 is screwed onto this ball screw shaft 6.

[0020] Therefore, when the electric motor 7 rotates the ball screw shaft 6 forward and backward, the nut member (not shown) screwed onto this ball screw shaft 6 slides along the ball screw shaft 6 in the Y-axis direction (front-rear direction) together with the slider 4. Thus, the chuck table 10 also moves integrally along the Y-axis direction together with this slider 4. As a result, the wafer W, which is the object to be polished held by the chuck table 10, also moves integrally along the Y-axis direction.

[0021] (Polishing mechanism) The polishing mechanism 20 comprises a spindle motor 22 fixed to a holder 21, a vertical spindle 23 rotationally driven by the spindle motor 22, a disc-shaped mount 24 attached to the lower end of the spindle 23, and a disc-shaped polishing pad 25 detachably mounted on the lower surface of the mount 24. Here, the polishing pad 25 is made of a nonwoven fabric containing abrasive grains, urethane, or the like.

[0022] The polishing mechanism 20 is movable up and down in the Z-axis direction (vertical direction) by a lifting mechanism 30, which, as shown in Figure 1, is provided on the -Y-axis end face (front) of a rectangular box-shaped column 102 that is erected vertically on the +Y-axis end (rear end) of the upper surface of the base 100. The lifting mechanism 30 moves the polishing mechanism 20 up and down in a direction perpendicular to the upper surface (holding surface) of the chuck table 10 (Z-axis direction), and moves a rectangular plate-shaped lifting plate 31 attached to the back of the holder 21 up and down in the Z-axis direction (vertical direction) along a pair of left and right guide rails 32, together with the holder 21 and the spindle motor 22, spindle 23, polishing pad 25, etc. held in the holder 21. Here, the pair of left and right guide rails 32 are arranged perpendicular and parallel to each other on the front surface of the column 102.

[0023] As shown in Figure 1, a rotatable ball screw shaft 33 is erected vertically along the Z-axis direction (up and down direction) between a pair of left and right guide rails 32, and the upper end of the ball screw shaft 33 is connected to a reversible electric motor 34, which is the drive source. The lower end of the ball screw shaft 33 is rotatably supported by a bearing (not shown) on a column 102, and a nut member (not shown) that protrudes horizontally toward the rear (+Y-axis direction) from the back of the lifting plate 31 is screwed onto this ball screw shaft 33.

[0024] (Processing room) As shown in Figure 1, a rectangular box-shaped cover 9 with an opening at the bottom is erected on the base 100. The machining chamber S inside this cover 9 houses a chuck table 10, a rotary drive mechanism 12, a polishing mechanism 20, a lifting mechanism 30, and the like. A control panel 35 for inputting and displaying various machining conditions is mounted on the front surface (Y-axis end face) of this cover 9.

[0025] (Polishing fluid supply unit and cleaning fluid supply unit) As shown in Figure 1, the polishing fluid supply unit 40 and the cleaning fluid supply unit 50 are housed at the bottom of the base 100. These polishing fluid supply unit 40 and cleaning fluid supply unit 50 are housed in a rectangular box-shaped case 36, and as shown in Figures 2 and 3, various components of the polishing fluid supply unit 40 and cleaning fluid supply unit 50 are arranged in a rectangular tray-shaped lower case 36A.

[0026] Specifically, the polishing fluid supply unit 40 includes a polishing fluid supply source 41, an on / off valve 43 connected to a pipe 42 extending from the polishing fluid supply source 41, and a polishing fluid flow rate adjustment unit 45 connected to a pipe 44 extending from the on / off valve 43. The pipe 46 extending from the polishing fluid flow rate adjustment unit 45 opens into the center of the polishing pad 25 of the polishing mechanism 20 shown in Figure 1. The cleaning fluid supply unit 50 also includes a cleaning fluid supply source 51, an on / off valve 53 connected to a pipe 52 extending from the cleaning fluid supply source 51, and a cleaning fluid flow rate adjustment unit 55 connected to a pipe 54 extending from the on / off valve 53. The pipe 56 extending from the cleaning fluid flow rate adjustment unit 55 is connected to a cleaning nozzle 57 bent in an inverted L shape as shown in Figure 1. Here, the cleaning nozzle 57 is provided at the front end (-Y axis direction end) on the base 100 and opens laterally (+X axis direction).

[0027] Incidentally, while either acidic or alkaline solutions are used for polishing and cleaning, to neutralize them, an alkaline cleaning solution is used when an acidic polishing solution is used, and an acidic cleaning solution is used when an alkaline polishing solution is used. Furthermore, when both the polishing and cleaning solutions are acidic or alkaline, the wafer is neutralized with pure water after cleaning.

[0028] Here, polishing fluid and cleaning fluid are harmful to the human body, and workers may inadvertently approach the cover 9 without realizing that the fluid has adhered to its outer surface during loading and unloading of wafers W into the processing room S. For this reason, in this embodiment, paint seals 2 (see Figure 4) coated with paint that changes color when exposed to polishing fluid or cleaning fluid are attached are affixed to the outer surface of the cover 9 in positions where workers may approach. Alternatively, instead of paint seals 2, paint may be directly applied to the outer surface of the cover 9 or the outer surface of the case 36 housing the polishing fluid supply unit 40 and the cleaning fluid supply unit 50. Furthermore, as shown in Figure 1, a waterproof pan 110 may be laid beneath the polishing device 1 corresponding to the bottom surface of the polishing device 1, and paint seals 2 may be affixed to the inner surface of the waterproof pan 110 or paint may be applied. In addition, a leak sensor (not shown) is provided on the waterproof pan 110, so that, for example, liquid leaking from the processing room S accumulates in the waterproof pan 110, the leak sensor detects the leak, and notifies the worker of the leak. Furthermore, the worker can determine whether the leaked liquid is water or a chemical solution by the color of the inner surface of the waterproof pan 110.

[0029] (Color detection unit) In this embodiment, a color sensor 60 is used as the color detection unit. This color sensor 60 detects the color change of a paint seal 2 (see Figure 4) coated with paint that changes color when polishing liquid or cleaning liquid adheres to it. The polishing apparatus 1 shown in Figure 1 has two color sensors 60 arranged in the two locations shown. As shown in Figure 4, each color sensor 60 emits light L1 toward the paint seal 2 coated with paint and receives reflected light L2 reflected by the paint seal 2 to detect the color of the paint seal 2, and is electrically connected to the determination unit 70 (see Figure 4) which will be described later. Note that a camera may be used instead of the color sensor 60 as the color detection unit, and the color of the paint seal 2 may be detected by the image captured by the camera.

[0030] (Judgment Department) The determination unit 70 shown in Figure 4 determines whether or not polishing liquid or cleaning liquid is adhering to the paint seal 2 based on the color of the paint seal 2 detected by the color sensor 60, and is electrically connected to the color sensor 60 and the indicator light 80 described later.

[0031] (indicator light) The indicator light 80, which constitutes the notification unit, has the function of notifying the worker if the judgment unit 70 determines that polishing liquid or cleaning liquid is adhering to the paint seal 2. In this embodiment, as shown in Figure 1, it is erected at the front end (-Y axis end) corner of the upper surface of the cover 9. When this indicator light 80 lights up or flashes, it notifies the worker that polishing liquid or cleaning liquid is adhering to the outer surface of the cover 9 and draws their attention to it. The notification unit may also draw the worker's attention to it using sound, such as a buzzer. Alternatively, the color sensor 60 may detect liquid leaked into the waterproof pan 110 and draw the worker's attention to it. Furthermore, the color or flashing pattern of the indicator light 80 may be changed depending on whether the liquid is acidic or alkaline to distinguish between acidic and alkaline and notify the worker accordingly.

[0032] [Operation of polishing equipment] Next, we will describe the polishing of the wafer W using the polishing apparatus 1 configured as described above.

[0033] When polishing the wafer W, the wafer W is placed face down on the upper surface (holding surface) of the chuck table 10. Then, the porous member 10A of the chuck table 10 is evacuated by a suction source (not shown), and the wafer W placed on the upper surface (holding surface) of the porous member 10A is held in place by suction to the holding surface.

[0034] From the above state, the horizontal movement mechanism 3 shown in Figure 1 is driven to move the chuck table 10 in the +Y axis direction (rearward), positioning the chuck table 10 and the wafer W held by it below the polishing pad 25 of the polishing mechanism 20. That is, when the electric motor 7 is started and the ball screw shaft 6 rotates, the slider 4, to which a nut member (not shown) that screws onto the ball screw shaft 6 is attached, slides along the pair of left and right guide rails 5 in the +Y axis direction together with the chuck table 10, etc., so that the chuck table 10 and the wafer W held by it are positioned below the polishing pad 25 of the polishing mechanism 20.

[0035] Furthermore, the electric motor 13 of the rotating mechanism 12 shown in Figure 1 is driven to rotate the chuck table 10 around the vertical central axis of the rotating shaft 11 at a predetermined rotational speed (for example, 300 rpm). That is, when the electric motor 13 is driven, the rotation of the output shaft (motor shaft) of the electric motor 13 is transmitted from the rotating shaft 11 to the chuck table 10 while being reduced in speed via the drive pulley 14, timing belt 16 and driven pulley 15, and the chuck table 10 and the wafer W held therein are driven to rotate at a predetermined speed. At the same time, the spindle motor 22 of the polishing mechanism 20 is started to rotate the polishing pad 25 around the vertical central axis at a predetermined speed (for example, 1000 rpm).

[0036] As described above, with the wafer W and polishing pad 25 rotating, the lifting mechanism 30 is driven to lower the polishing pad 25 in the -Z axis direction. That is, when the electric motor 34 is driven and the ball screw shaft 33 rotates, the lifting plate 31, which is equipped with a nut member (not shown) that screws onto the ball screw shaft 33, lowers in the -Z axis direction together with the polishing pad 25. Then, the lower surface (polishing surface) of the polishing pad 25 comes into contact with the entire upper surface (back surface) of the wafer W. At this point, when the on / off valve 43 of the polishing fluid supply unit 40 shown in Figures 2 and 3 is opened, the polishing fluid from the polishing fluid supply source 41 is supplied from the piping 46 to the contact surface (polishing surface) between the polishing pad 25 and the wafer W after its flow rate is controlled by the polishing fluid flow rate adjustment unit 45.

[0037] Therefore, the upper surface of the wafer W is polished by the polishing pad 25 while receiving a supply of polishing fluid, and the grinding marks remaining on the upper surface of the wafer W are removed, thereby increasing the flexural strength of the wafer W.

[0038] Then, when the polishing of the wafer W is complete, the horizontal movement mechanism 3 shown in Figure 1 is driven, and the chuck table 10 and the wafer W held therein move in the -Y axis direction (forward) to the position where the cleaning nozzle 57 is located. At this point, the cleaning liquid supply unit 50 sprays cleaning liquid from the cleaning nozzle 57 toward the upper surface of the wafer W, removing foreign matter such as polishing debris adhering to the upper surface of the wafer W and cleaning the upper surface of the wafer W. That is, when the on / off valve 53 of the cleaning liquid supply unit 50 shown in Figures 2 and 3 is opened, the cleaning liquid from the cleaning liquid supply source 51 is supplied to the cleaning nozzle 57 via the piping 56 after its flow rate is controlled by the cleaning liquid flow rate adjustment unit 55, and as described above, the cleaning liquid is sprayed from the spray nozzle 57 toward the upper surface of the wafer W.

[0039] By the way, during the polishing of the wafer W, an acidic or alkaline polishing solution is used to supply the polishing solution to the contact surface (polishing surface) between the wafer W and the polishing pad 25. Therefore, in order to neutralize the polishing solution, an alkaline cleaning solution is used when an acidic polishing solution is used, and an acidic cleaning solution is used when an alkaline polishing solution is used.

[0040] However, since acidic or alkaline polishing and cleaning solutions are harmful to workers before neutralization, in this embodiment, as described above, paint seals 2 (see Figure 4) coated with paint that changes color when exposed to polishing or cleaning solutions are attached are affixed to the outer surface of the cover 9 in positions where workers may approach. A color sensor 60 is provided to detect the color of the paint seal 2, and a determination unit 70 is provided to determine whether or not polishing or cleaning solutions have adhered to the paint seal 2 based on the color detected by the color sensor 60. If the determination unit 70 determines that polishing or cleaning solutions have adhered to the paint seal 2 due to the discoloration of the paint seal 2, the indicator light 80 constituting the notification unit lights up or flashes to alert the worker. This will be explained below according to the flowchart shown in Figure 5.

[0041] As shown in Figure 4, when the color sensor 60 emits light L1 toward the paint seal 2 (step S1 in Figure 5), the light L1 is reflected by the paint seal 2, and when the color sensor 60 receives the reflected light L2 (step S2), the color sensor 60 detects the color of the paint seal 2 based on the wavelength of the reflected light L2 (step S3), and transmits the detection signal toward the determination unit 70.

[0042] The determination unit 70 then determines whether the paint seal 2 has changed color from its original color (step S4). If discoloration of the paint seal 2 is observed (step S4: Yes), the determination unit 70 lights up or flashes the indicator light 80 to inform the operator that polishing fluid or cleaning fluid has adhered to the outer surface of the cover 9 (step S5). The same process is then repeated (step S6).

[0043] On the other hand, if the determination unit 70 does not detect any discoloration of the paint seal 2 (step S4: No), the above series of processes is repeated without any notification (step S6).

[0044] As described above, in the polishing apparatus 1 according to this embodiment, a paint seal 2 coated with paint that changes color when exposed to polishing liquid or cleaning liquid is attached is attached to a position on the outer surface of the cover 9 where polishing liquid or cleaning liquid is likely to adhere. The color of the paint seal 2 is detected by a color sensor 60, and the determination unit 70 determines whether or not polishing liquid or cleaning liquid has adhered to the paint seal 2 based on the color of the paint seal 2 detected by the color sensor 60. If the paint seal 2 changes color and it is determined that polishing liquid or cleaning liquid has adhered to the paint seal 2, the indicator light 80 constituting the notification unit is turned on or flashed. This effectively alerts the operator and prevents them from inadvertently coming into contact with the polishing liquid or cleaning liquid.

[0045] The polishing fluid can be white or colored, such as purple. In the case of colored polishing fluid, the color sensor 60 can be used to detect the fluid. Therefore, even without using the paint seal 2, the leakage of the polishing fluid can be detected and the notification unit can alert the worker.

[0046] Although the above description concerns an application of the present invention to a polishing apparatus for polishing wafers, the present invention can be similarly applied to a polishing apparatus for polishing any workpiece other than wafers.

[0047] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the technical idea described in the claims, specification, and drawings. [Explanation of Symbols]

[0048] 1: Polishing device, 2: Paint seal, 3: Horizontal movement mechanism, 4: Slider, 5: Guide rail, 6: Ball screw shaft, 7: Electric motor, 8: Bearing, 9: Cover, 10: Chuck table, 10A: Porous member, 11: Rotating shaft, 12: Rotary drive mechanism, 13: Electric motor, 14: Drive pulley, 15: Driven pulley, 16: Timing belt, 20: Polishing mechanism, 21: Holder, 22: Spindle motor, 23: Spindle, 24: Mount, 25: Polishing pad, 30: Lifting mechanism 31: Lifting plate, 32: Guide rail, 33: Ball screw shaft, 34: Electric motor, 35: Control panel, 36: Case, 36A: Lower case, 40: Polishing fluid supply unit, 41: Polishing fluid supply source, 42: Piping, 43: On / off valve, 44: Piping, 45: Polishing fluid flow rate adjustment unit, 46: Piping, 50: Cleaning fluid supply unit, 51: Cleaning fluid supply source, 52: Piping, 53: On / off valve, 54: Piping, 55: Cleaning fluid flow rate adjustment unit, 56: Piping, 57: Cleaning nozzle, 60: Color sensor (color detection unit), 70: Judgment unit, 80: Indicator light (notification unit), 100: Base, 101: Internal base, 102: Column, 110: Waterproof pan, L1: Outgoing light, L2: Reflected light, S: Processing room, W: Wafer

Claims

1. A polishing apparatus for polishing wafers comprises a chuck table for holding a wafer on a holding surface, a polishing mechanism for polishing the wafer with a polishing pad, a processing chamber housing the chuck table and the polishing mechanism, and a polishing liquid supply unit for supplying an acidic or alkaline polishing liquid to the polishing pad in the processing chamber, A polishing apparatus that applies a paint to the outer surface of the processing chamber that changes color when the polishing liquid comes into contact with it.

2. The polishing apparatus according to claim 1, wherein the polishing liquid supply unit is coated with a paint that changes color when the polishing liquid comes into contact with it.

3. Equipped with a cleaning solution supply unit that supplies acidic or alkaline cleaning solutions, The polishing apparatus according to claim 1, wherein the cleaning fluid supply unit is coated with a paint that changes color when the cleaning fluid comes into contact with it.

4. A color detection unit that receives light reflected by the paint and detects its color, A determination unit that determines whether an acidic or alkaline liquid is present based on the color detected by the color detection unit, A notification unit that notifies the worker based on the judgment of the judgment unit, The polishing apparatus according to claim 1, comprising:

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