Cleaning Equipment

Abstract

To shorten cleaning time even when many deposits adhere to the whole or a portion of a wafer.SOLUTION: By imaging the whole of a surface of a wafer 10 while rotating the wafer and making the image a band-like image 100 with the radial direction of the wafer 10 as the vertical axis and the rotation angle of the wafer 10 as the transverse axis, distribution of amounts of processing chips 101-104 on the wafer 10 and positions to which the processing chips 101-104 adhere can be recognized. Therefore, a portion to which many processing chips adhere can be predominantly re-cleaned and time required for cleaning can be shortened since there is no need to re-clean the whole evenly.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a cleaning apparatus for cleaning a wafer. [Background technology]

[0002] When a wafer is subjected to processing such as grinding, polishing, cutting, etc., processing debris adheres to the upper surface of the wafer after processing, so the wafer is cleaned for a predetermined time by spraying water or the like onto the wafer while rotating it. The predetermined time is determined by a cleaning experiment (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-131186 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a large amount of contaminants are present on the wafer, the contaminants cannot be removed by cleaning for a certain period of time alone, and additional cleaning becomes necessary. Furthermore, in cases where the deposits are concentrated on a particular portion of the wafer, cleaning for a given period of time alone will not be enough to leave the deposits on that portion, making additional cleaning necessary in this case as well.

[0005] SUMMARY OF THE PRESENT EMBODIMENT The present invention has been made in consideration of such problems, and has as its object to shorten the cleaning time even when a large amount of deposits are attached to the whole or part of the wafer. [Means for solving the problem]

[0006] The present invention provides a cleaning device comprising a holding table which holds a wafer on a holding surface, a rotation mechanism which rotates the holding table holding the wafer around the center of the holding surface, a cleaning tool which cleans the wafer with a cleaning nozzle which sprays cleaning water onto the wafer or a cleaning sponge which comes into contact with the wafer, and a moving mechanism which moves the cleaning tool in a direction parallel to the holding surface, and further comprising an imaging mechanism which extends in the radial direction of the upper surface of the wafer held by the holding surface and images at least a radial portion of the upper surface of the wafer, and a control unit which rotates the holding table and controls to determine the presence or absence of adhesion on the upper surface of the wafer based on the image formed by the imaging mechanism, and the imaging mechanism is a line sensor in which the pixels of the image formed form at least one straight line. and a light extending parallel to the line sensor and having the same length as the line sensor, the control unit comprising: a rotation control unit that controls the rotation angle of the holding table so that the pixels on the outer circumferential edge of the wafer in the captured image are adjacent in the circumferential direction of the wafer; an imaging control unit that causes the line sensor to capture an image each time the holding table rotates by the predetermined angle; an editing unit that edits the captured image into a band-shaped image showing the gradation of each pixel for each rotation angle, with the radial direction of the wafer as the vertical axis and the rotation angle of the holding table as the horizontal axis, or with the rotation angle of the holding table as the vertical axis and the radial direction of the wafer as the horizontal axis; and a judgment unit that judges pixels in the band-shaped image whose gradation is smaller than a predetermined value set in advance to be adhesions. It is preferable that the control unit includes a positioning control unit that controls the movement mechanism to position the cleaning tool at a position corresponding to the pixel determined as having a deposit by the determination unit. The line sensor may have a length capable of capturing an image of the diameter of the wafer held by the holding surface. Effect of the Invention

[0007] In the present invention, the entire surface of the wafer is imaged, and the image is converted into a band-shaped image, which allows the amount of adhesions on the wafer and the distribution of the positions where the adhesions are attached to be recognized. Therefore, it is possible to focus on re-cleaning the areas where a lot of adhesions are attached, and since it is not necessary to re-clean the entire surface evenly, the time required for cleaning can be shortened. In addition, since it is possible to grasp the tendency of the positions where adhesions are abundant, it is also possible to set cleaning conditions that focus on cleaning the areas where a lot of adhesions are attached in advance, which makes it possible to eliminate the need for re-cleaning. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an example of a cleaning device. [Diagram 2] FIG. 13 is a perspective view showing an example in which a wafer is supported on a frame via a tape. [Diagram 3] FIG. 2 is a front view showing a state in which an imaging mechanism is positioned above a wafer. [Figure 4] FIG. 2 is a side view showing a state in which an imaging mechanism is positioned above a wafer. [Diagram 5] FIG. 2 is a plan view showing a state in which an imaging mechanism is located above a wafer. [Figure 6] FIG. 2 is an image diagram showing a first example of a band-like image. [Figure 7] FIG. 13 is a plan view showing a state in which a second example of an imaging mechanism is positioned above a wafer. [Figure 8] FIG. 2 is an image diagram showing a first example of a band-like image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The cleaning apparatus 1 shown in FIG. 1 includes a holding table 2 having a holding surface 21 for holding a wafer, a rotation mechanism 3 for rotating the holding table 2 about an axis 20 passing through the center of the holding surface 21, a cleaning tool 4 for cleaning the wafer held on the holding table 2, and a moving mechanism 5 for moving the cleaning tool 4 in a direction parallel to the holding surface 21.

[0010] The holding table 2 includes an adsorption section 22 having a holding surface 21, and a frame 23 supporting the adsorption section 22. As shown in Fig. 2, the wafer 10 held on the holding surface 21 has a device 11 formed on its front surface and a tape 12 attached to its back surface. A frame 13 is attached to the peripheral portion of the tape 12, and the wafer 10 is supported by the frame 13 via the tape 12. The wafer 10 is held by the frame 13 via the tape 12 only when the wafer 10 is cut. For example, when the back surface of the wafer 10 is ground or polished, usually only the tape is attached to the front surface, and the frame 13 is not used.

[0011] The frame 23 is provided with a plurality of clamp mechanisms 24 for holding the frame 13 on its periphery. The clamp mechanism 24 includes a fixed portion 241 fixed to the frame 23 and a rotating member 242 that rotates around a horizontal axis relative to the fixed portion 241. A pressing portion 243 for pressing the wafer is formed at the upper end of the rotating member 242, and a weight is provided at the lower end 244 of the rotating member 242. When the holding table 2 is stationary, the weight of the weight keeps the pressing portion 243 away from the upper surface of the frame 23. When the holding table 2 is driven by the rotating mechanism 3 to rotate, the rotating member 242 rotates in a direction in which the lower end 244 rises due to centrifugal force, so that the pressing portion 243 presses the wafer. The clamp mechanism 24 shown in FIG. 1 is a so-called pendulum type, but a mechanical clamp may be used instead. Moreover, the holding table 2 is driven by a lifting mechanism 25 so as to be able to move up and down.

[0012] The rotation mechanism 3 includes a shaft 31 connected to the lower part of the frame 23, a motor 32 connected to the shaft 31, and an encoder 33 that recognizes the rotation angle of the holding table 2. When the shaft 31 is driven by the motor 32 to rotate, the holding table 2 rotates, and the rotation angle is recognized by the encoder 33.

[0013] The cleaning tool 4 includes a water nozzle 41 that sprays high-pressure cleaning water downward, and an air nozzle 42 that sprays high-pressure air downward. The water nozzle 41 and the air nozzle 42 are supported by a moving mechanism 5 so as to be movable in a direction parallel to the holding surface 21. The moving mechanism 5 includes a first arm 51 having the water nozzle 41 at its tip and extending in a direction parallel to the holding surface 21, a second arm 52 having the air nozzle 42 at its tip and extending in a direction parallel to the holding surface 21, a shaft portion 53 to which one ends of the first arm 51 and the second arm 52 are fixed and having a rotation axis perpendicular to the holding surface 21, and a motor (not shown) that is connected to the lower end of the shaft portion 53 and rotates the shaft portion 53 around the axis perpendicular to the holding surface 21. The cleaning tool 4 may be configured to include a cleaning sponge, instead of the water nozzle 41 and the air nozzle 42, that comes into contact with the wafer to clean it.

[0014] The cleaning device 1 is provided with a cylindrical cover 61 that covers the holding table 2, the rotating mechanism 3, the cleaning tool 4, and the moving mechanism 5 from the outer periphery, and prevents the cleaning water that splashes as the holding table 2 rotates from splashing outside. In addition, the cover 61 is provided with a housing 62 on the outer periphery, and the housing 62 is provided with an exhaust duct 63 for discharging the cleaning water.

[0015] The cleaning device 1 includes an imaging mechanism 7 that images the top surface of the wafer held on the holding surface 21. The imaging mechanism 7 extends in the radial direction of the wafer held on the holding surface 21 and can image at least the radial portion of the wafer. The imaging mechanism 7 is supported by a lifting cylinder 73 so that it can be raised and lowered. As shown in FIG. 3, the imaging mechanism 7 includes a line sensor 71 in which pixels of an image are in at least one straight line, and a light 72 that extends parallel to the longitudinal direction of the line sensor 71 and has the same length as the line sensor 71. The optical axis of the line sensor 71 is inclined at 45 degrees with respect to the direction perpendicular to the holding surface 21, and the optical axis of the light 72 is inclined at 45 degrees with respect to the direction perpendicular to the holding surface 21 and forms an angle of 90 degrees with the optical axis of the line sensor 71, so that the reflected light at the location illuminated by the light 72 can be imaged by the line sensor 71.

[0016] 1, the cleaning apparatus 1 includes a control unit 8 that rotates the holding table 2 and performs control for determining the presence or absence of adhesion on the upper surface of the wafer based on the captured image formed by the imaging mechanism 7. The control unit 8 includes a rotation control unit 81 that controls the rotation of the holding table 2 so that pixels on the outer periphery of the wafer in the captured image are adjacent to each other in the circumferential direction, an imaging control unit 82 that causes the line sensor 71 to capture an image every time the holding table 2 rotates a predetermined angle, an editing unit 83 that edits the captured image into a band-shaped image by showing the gradation of each pixel for each rotation angle, with the radial direction of the wafer as the vertical axis and the rotation angle of the holding table 2 as the horizontal axis, or with the rotation angle of the holding table 2 as the vertical axis and the radial direction of the wafer as the horizontal axis, and a determination unit 84 that determines pixels in the band-shaped image whose gradation is smaller than a predetermined value set in advance as adhesion.

[0017] For example, as shown in Fig. 3, a tape 12 is applied to the front surface of a wafer 10 after backside grinding, and the protective tape 12 side is suction-held on a holding surface 21. In this case, the frame 13 shown in Fig. 2 is not used, and therefore the clamp mechanism 24 shown in Fig. 1 is omitted from Fig. 3 and subsequent figures.

[0018] When the wafer 10 is held by suction on the holding surface 21, the holding table 2 is rotated by the rotation mechanism 3 shown in Fig. 1, and the cleaning tool 4 is oscillated above the wafer 10 around the axis 53 by the movement mechanism 5 while high-pressure water is sprayed from the water nozzle 41 to clean the entire surface of the wafer 10 for a predetermined time. After this cleaning, the spraying of high-pressure water is stopped, and while continuing to rotate the holding table 2, high-pressure air is sprayed from the air nozzle 42 while the cleaning tool 4 is oscillated, thereby removing water remaining on the wafer 10 and drying it.

[0019] Next, the cleaning tool 4 is removed from above the wafer 10, and the imaging mechanism 7 is moved above the wafer 10 as shown in Figs. 3 and 4, so that the imaging mechanism 7 is positioned above at least the radial portion of the wafer 10. Then, as shown in Fig. 5, the rotation control unit 81 rotates the holding table 2 in the direction of the arrow 120, while the light 72 illuminates the surface of the wafer 10, and the illuminated portion is imaged by the line sensor 71. Here, the rotation speed of the holding table 2 is such that the peripheral portion of the wafer 10 appears in pixels without gaps and without overlaps in relation to the imaging by the line sensor 71. That is, the imaging control unit 82 controls the timing of imaging in relation to the rotation speed of the holding table 2 based on the output of the encoder 33 so that the image of the peripheral portion of the wafer 10 can be acquired without gaps and without overlaps. Note that there is more overlap of images near the center of the holding table 2.

[0020] When the holding table 2 rotates once while the line sensor 71 is capturing an image in this manner, the rotation of the holding table 2 by the rotation mechanism 3 and the capturing of the image by the line sensor 71 by the image capturing control unit 82 are stopped. Then, based on each acquired image, the editing unit 83 edits the pixel gradation for each rotation angle into a band-like image with the radial direction of the wafer 10 as the vertical axis and the rotation angle of the holding table 2 as the horizontal axis. For example, as shown in Fig. 5, in the case where processing debris 101, 102, and 104 are attached to the outer periphery, which is a portion close to the periphery of the wafer 10, and processing debris 103 is attached to a position close to the center of the wafer 10, the editing unit 83 forms a band-like image 100 shown in Fig. 6. In addition, in the band-shaped image 100, the processing debris 101, 102, 104 and the processing debris 103 are shown to have the same length in the horizontal axis direction. Since the processing debris 103 has been imaged more times than the processing debris 101, 102, and 104, when the processing debris 103 has the same length in the horizontal axis direction of the band-shaped image 100, the processing debris 103 adhering to the wafer is smaller than the processing debris 101, 102, and 104.

[0021] In this band-shaped image 100, the bottom end of the vertical axis is the center of the wafer 10, and the top end of the vertical axis is the edge of the wafer 10. Additionally, the left end of the horizontal axis of the band-shaped image 100 is the start of imaging (rotation angle is 0 degrees), and the right end of the horizontal axis is the end of imaging (rotation angle is 360 degrees).

[0022] The determination unit 84 sets the color of the wafer 10 in the band-shaped image 100 to white with the highest gradation, and determines that pixels with a gradation value smaller than a preset predetermined value are attached. Here, the preset predetermined value is, for example, a value with a gradation value slightly lower than white. Then, in the band-shaped image 100 shown in FIG. 6, the determination unit 84 determines that the processing debris 101 to 104 are attached. From the band-shaped image 100, it can be seen that the processing debris is concentrated on the outer periphery of the wafer 10 because the processing debris 101, 102, and 104 are located at the upper part of the band-shaped image 100. The determination unit 84 may determine that an image that is determined to possibly be an object in the band-like image is an object if the length of the image exceeds a preset length. In addition, a range (a pre-set range) may be set for a pre-set length, and if the length of an image determined to be an attachment is too long beyond the pre-set range, it may be determined to be, for example, a scratch rather than an attachment. Furthermore, the preset length or the preset range may be set to a different length or a different range depending on the position of the vertical axis (radial direction of the wafer 10) of the band-like image 100. In other words, the preset length near the center of the wafer may be set to be longer than the preset length near the outer periphery of the wafer.

[0023] When the positions where the processing debris 101-104 are attached can be recognized in this way, re-cleaning is performed to remove the processing debris 101-104. Specifically, the imaging mechanism 7 is retracted from above the wafer 10, the holding table 2 is rotated, and high-pressure water is sprayed from the water nozzle 41 of the cleaning tool 4. At this time, the water nozzle 41 controls the moving speed of the cleaning tool 4 so that the time spent in the vicinity of the outer periphery of the wafer 10 where the processing debris 101, 102, 104 are concentrated is extended, or the cleaning tool 4 is stopped near the outer periphery of the wafer 10, thereby positioning the cleaning tool 4 intensively at the outer periphery of the wafer 10, thereby efficiently removing the processing debris 101, 102, 104. That is, the control unit 8 includes a positioning control unit that positions the cleaning tool 4 at a position corresponding to the pixel determined by the determination unit 84 to be an attachment.

[0024] Furthermore, if the judgment unit 84 makes a similar judgment for a plurality of wafers 10 and it is found that a large amount of processing debris tends to adhere to the outer periphery of each of the plurality of wafers 10, the speed of movement of the cleaning tool 4 can be controlled so that the time that the water nozzle 41 is positioned on the outer periphery of the wafer 10 is long in the initial cleaning stage, thereby effectively removing the processing debris and making re-cleaning unnecessary. For example, the radial region of the wafer 10 may be divided into a plurality of regions, such as a central region, a middle region, and an outer periphery region, and the number of processing debris may be found for each region, and the horizontal movement speed of the cleaning tool 4 may be adjusted depending on the magnitude of the number. In this way, by optimizing the cleaning conditions according to the concentration of processing debris, additional cleaning can be eliminated.

[0025] 7, the imaging mechanism 7 may have a length equal to or greater than the diameter of the wafer 10. In this case, the imaging mechanism 7 is positioned in a diameter area passing through the center of the wafer 10. Then, while the holding table 2 holding the wafer 10 on the holding surface 21 is rotated in the direction of the arrow 120, the surface of the wafer 10 is illuminated by the light 72, and the illuminated portion is imaged by the line sensor 71. The rotation speed of the holding table 2 here is also set so that the peripheral portion of the wafer 10 appears in pixels without gaps or overlaps when imaged by the line sensor 71.

[0026] When the holding table 2 rotates half a turn while the line sensor 71 is capturing an image in this manner, the rotation of the holding table 2 by the rotation mechanism 3 and the capturing of the image by the line sensor 71 by the image capturing control unit 82 are stopped. Then, the editing unit 83 edits the pixel gradation for each rotation angle into a band-shaped image based on each image, with the radial direction of the wafer 10 as the vertical axis and the rotation angle of the holding table 2 as the horizontal axis. For example, the band-shaped image 110 shown in FIG. 8 has the radial direction of the wafer 10 as the vertical axis and the rotation angle of the holding table 2 as the horizontal axis. The center of the vertical axis is the center of the wafer 10, and the upper and lower ends are the periphery of the wafer 10. Also, the left end of the horizontal axis of the band-shaped image 100 is the start of capturing (rotation angle is 0 degrees), and the right end of the horizontal axis is the end of capturing (rotation angle is 180 degrees).

[0027] The determination unit 84 sets the color of the wafer 10 in the belt-shaped image 110 to be white with the highest gradation, and determines that pixels with a gradation value smaller than a predetermined value set in advance are attached matter. In the belt-shaped image 100 shown in Fig. 8, the processing debris 101 to 104 are determined to be attached matter. Of these, the processing debris 101, 102, and 104 are located at the upper part of the belt-shaped image 100, and therefore it can be seen that the processing debris is concentrated on the outer periphery of the wafer 10.

[0028] 8, in the belt-shaped image 110, the processing debris 101, 102, and 104 are concentrated at the top and bottom ends in the vertical direction. This shows that the processing debris is concentrated on the outer periphery of the wafer 10. Therefore, by controlling the movement of the cleaning tool 4 so as to lengthen the time that the water nozzle 41 of the wafer 10 is positioned on the outer periphery of the wafer 10, the processing debris 101, 102, and 104 can be efficiently removed.

[0029] Also, as described above, if it is found that a large amount of processing debris tends to adhere to the outer periphery of the wafers 10 for multiple wafers 10, the processing debris can be effectively removed and re-cleaning can be eliminated by controlling the movement speed of the cleaning tool 4 so that the water nozzle 41 is positioned on the outer periphery of the wafers 10 for a long time during the initial cleaning stage.

[0030] In this way, by capturing an image of the entire surface of the wafer 10 and forming the image in a band-like form, it is possible to recognize the amount of adhesions on the wafer 10 and the distribution of the positions where the adhesions are attached. Therefore, it is possible to focus on re-cleaning the areas where a lot of adhesions are attached, and since it is not necessary to re-clean the entire surface evenly, it is possible to shorten the time required for cleaning. In addition, since it is possible to grasp the tendency of the positions where adhesions are abundant, it is also possible to set cleaning conditions that focus on cleaning the areas where a lot of adhesions are attached in advance, thereby making it possible to eliminate the need for re-cleaning.

[0031] In this embodiment, the cleaning device 1 is described as a standalone device, but the cleaning device 1 may be mounted on a processing device. [Explanation of symbols]

[0032] 1: Cleaning equipment 2: Holding table 20: Axis 21: Holding surface 22: Adsorption part 23: Frame 24: Clamp mechanism 241: Fixed portion 242: Rotating member 243: Holding portion 244: Lower end portion 25: Lifting mechanism 3: Rotation mechanism 31: Shaft 32: Motor 33: Encoder 4: Cleaning tool 41: Water nozzle 42: Air nozzle 5: moving mechanism 51: first arm 52: second arm 53: shaft 61: Cover 62: Housing 63: Exhaust duct 7: Imaging mechanism 71: Line sensor 72: Light 73: Lifting cylinder 8: Control unit 81: Rotation control unit 82: Imaging control unit 83: Editing unit 84: Determination unit 10: Wafer 11: Device 12: Tape 13: Frame 100, 110: Strip image 101, 102, 103, 104: Processing waste 110: Strip image

Claims

1. A cleaning device comprising: a holding table that holds a wafer on a holding surface; a rotation mechanism that rotates the holding table that holds the wafer around the center of the holding surface; a cleaning tool that cleans the wafer with a cleaning nozzle that sprays cleaning water onto the wafer or a cleaning sponge that comes into contact with the wafer; and a movement mechanism that moves the cleaning tool in a direction parallel to the holding surface, an imaging mechanism extending in a radial direction of the upper surface of the wafer held by the holding surface and imaging at least a radial portion of the upper surface of the wafer; a control unit that performs control to rotate the holding table and determine the presence or absence of adhesion on the upper surface of the wafer based on an image captured by the imaging mechanism, The imaging mechanism includes a line sensor in which pixels of the captured image are arranged in at least one straight line, and a light extending parallel to the line sensor and having the same length as the line sensor; the control unit is a rotation control unit that controls a rotation angle of the holding table so that the pixels on the outer circumferential edge of the wafer in the captured image are adjacent to each other in the circumferential direction of the wafer; an imaging control unit that causes the line sensor to capture an image every time the holding table rotates by a predetermined angle; an editing unit that edits the captured image into a band-shaped image showing the gradation of each pixel for each rotation angle, with the radial direction of the wafer as the vertical axis and the rotation angle of the holding table as the horizontal axis, or with the rotation angle of the holding table as the vertical axis and the radial direction of the wafer as the horizontal axis; a determination unit that determines that a pixel having a gradation smaller than a predetermined value in the belt-shaped image is an attachment; A cleaning device comprising:

2. The control unit includes a positioning control unit that controls the movement mechanism to position the cleaning tool at a position corresponding to the pixel determined by the determination unit to be a deposit.

2. The cleaning device according to claim 1.

3. The line sensor has a length capable of capturing an image of the diameter of the wafer held by the holding surface.

2. The cleaning device according to claim 1.

Images