Protective member forming device and protective member forming method

Abstract

To form a protective member in a protective member forming device by preventing air pockets from forming between a holding table and a sheet.SOLUTION: A protective member forming device (20) includes a holding table (21) that holds a sheet (11) by a holding surface (22), a sheet supply mechanism (30) that supplies the sheet to the holding table, and an adhering mechanism (40, 41) that adheres the sheet held on the holding table to a wafer (W), and further includes a light (28) that illuminates the sheet held on the holding table, a camera (47) that images the sheet, and a determining unit (52) that determines whether air is present between the holding table and the sheet on the basis of differences in color tone, brightness, or color difference in the image captured by the camera.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a protective member forming apparatus for forming a protective member that protects a wafer, and a method for forming a protective member. [Background technology]

[0002] When both sides of sliced ​​wafers cut from an ingot are ground to produce wafers of a desired thickness, a protective member is formed on the entire surface of one side of the wafer, the wafer is held on a chuck table of a grinding device via the protective member, and the other side of the wafer is ground using a grinding wheel.

[0003] In the protective member forming device that forms the protective member, liquid resin is supplied to a sheet placed on a holding table, and the liquid resin on the sheet is spread by a wafer and then hardened. In other words, the protective member is composed of a sheet and resin (hardened liquid resin).

[0004] When forming a protective member using a protective member forming device, as disclosed in Patent Document 1, air trapped between the sheet and the holding table is removed by pressing the sheet against the holding table with a roller to prevent air bubbles from being trapped between the sheet and the holding table. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-174883 Summary of the Invention [Problem to be solved by the invention]

[0006] However, even when air is removed using rollers, air pockets (air bubbles) can form between the holding table and the sheet due to factors such as dust adhering to the top surface of the holding table or the underside of the sheet. If the protective member is formed when there is an air pocket between the holding table and the sheet, the thickness of the protective member will be thin at the air pocket, resulting in an uneven thickness for the entire protective member. If the wafer is ground while supported by a protective member with an uneven thickness, the in-plane thickness of the ground wafer will not be uniform.

[0007] Therefore, the protective member forming apparatus and the protective member forming method have a problem to be solved, which is to form the protective member without creating an air pocket between the holding table and the sheet. [Means for solving the problem]

[0008] One aspect of the present invention is a protective member forming device comprising a holding table that holds a sheet by a holding surface, a sheet supply mechanism that supplies the sheet to the holding table, and an attachment mechanism that attaches the sheet held on the holding table to a wafer, and further comprising a light that illuminates the sheet held on the holding table, a camera that images the sheet, and a judgment unit that judges whether air is present between the holding table and the sheet based on differences in color tone, brightness, or color difference in the image captured by the camera.

[0009] One aspect of the present invention is a method for forming a protective member on one side of a wafer using the above-mentioned protective member forming apparatus, which includes a sheet holding step in which the sheet is held on the holding table; an imaging step in which the sheet is imaged with the camera; a determination step in which, in the image taken in the imaging step, a difference in color tone, brightness, or color difference is used to determine whether air is present between the holding table and the sheet; and a notification step in which, if it is determined in the determination step that air is present, a notification unit notifies an operator; or, if it is determined in the determination step that no air is present, a protective member forming step in which the sheet is attached to the wafer to form a protective member that protects one side of the wafer.

[0010] The protective member forming process includes an expansion process in which liquid resin is supplied between the sheet and the wafer and spread over the entire surface of one side of the wafer, and a hardening process in which the liquid resin expanded by the expansion process is hardened, and the sheet is attached to the wafer via the hardened liquid resin. [Effects of the Invention]

[0011] According to each of the above aspects, by checking whether there is air between the holding table and the sheet based on the image captured by the camera, it is possible to form a protective member of uniform thickness without creating air pockets between the holding table and the sheet. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a perspective view of a protective member forming device. [Figure 2] 10 is a cross-sectional view showing a state in which an imaging step and a judging step are performed in the protective member forming device. FIG. [Figure 3] 10A and 10B are diagrams illustrating examples of captured images to be referred to in a determination process. [Figure 4] FIG. 10 is a cross-sectional view showing the expansion step. [Figure 5] FIG. 10 is a cross-sectional view showing the expansion step. [Figure 6] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a protective member forming apparatus and a protective member forming method according to this embodiment will be described with reference to the drawings. The X-axis, Y-axis, and Z-axis directions shown in each drawing are perpendicular to one another. The X-axis and Y-axis directions are horizontal. The Z-axis direction is the up-down direction, with the +Z direction side being the top and the -Z direction side being the bottom.

[0014] The protective member forming apparatus 20 shown in FIG. 1 is an apparatus for forming a protective member 10 (see FIGS. 5 and 6 ) that covers the entire surface of one side of a wafer W. The surface of the wafer W that faces upward during processing in the protective member forming apparatus 20 is referred to as the upper surface Wa, and the surface that faces downward is referred to as the lower surface Wb. The wafer W is, for example, a disk-shaped sliced ​​wafer cut from a cylindrical ingot of silicon or the like. After the protective member 10 is formed by the protective member forming apparatus 20, the wafer W is transported to a grinding apparatus (not shown), where the protective member 10 side of the wafer W is placed and held on a holding surface of a chuck table of the grinding apparatus, and the upper surface Wa of the wafer W is ground with a grinding wheel. Note that the wafer W is not limited to a sliced ​​wafer before devices are formed thereon, but may also be a device wafer after devices are formed thereon.

[0015] In forming the protective member 10 in the protective member forming apparatus 20, the sheet 11 is held by the holding surface 22 of the holding table 21 (see FIG. 2), liquid resin 12 is supplied onto the sheet 11 from above the holding table 21 (see FIG. 4), and the lower surface Wb of the wafer W, whose upper surface Wa is held by the wafer holding table 40, is pressed from above against the holding table 21 to spread the liquid resin 12 (see FIG. 5). In the spread state, the liquid resin 12 is hardened, and the protective member 10 is formed by the sheet 11 and the hardened resin 13 (see FIG. 6).

[0016] The sheet 11 is made of a light-transmitting material. For example, a sheet made of polyethylene terephthalate or the like can be used as the sheet 11. Note that the sheet 11 made of a material other than this may also be used.

[0017] The liquid resin 12 has the property of being hardened by a predetermined external stimulus. In this embodiment, the liquid resin 12 is an ultraviolet-curable resin, and when the liquid resin 12 (see FIG. 5) is spread so as to cover the entire lower surface Wb of the wafer W, it is hardened to become resin 13 (see FIG. 6) by irradiating it with ultraviolet light. Note that the external stimulus applied to harden the liquid resin 12 is not limited to irradiation with ultraviolet light, and may be a temperature change such as heating or cooling, or irradiation of light of a wavelength other than ultraviolet light.

[0018] As shown in FIG. 1, the protective member forming apparatus 20 has a cassette storage section 23 at its end on the -X direction side. The cassette storage section 23 has two storage spaces formed at different positions in the Y-axis direction and opening to the +X direction side. An input cassette 24 that stores wafers W before the protective member 10 is formed is placed in one of the storage spaces. An output cassette 24 that stores wafers W after the protective member 10 has been formed is placed in the other storage space. Each cassette 24 can store multiple wafers W.

[0019] A temporary placement table 25 and a sheet cutting table 26 are provided at positions on the +X direction side of the cassette housing section 23. The temporary placement table 25 is located on the upper side, and the sheet cutting table 26 is located on the lower side. The temporary placement table 25 is provided with a wafer detection unit 251 that detects the center position and orientation of the wafer W before the protective member 10 is formed. The sheet cutting table 26 is provided with a sheet cutter 261 that cuts the sheet 11 attached to the wafer W along the outline of the wafer W.

[0020] A first transport mechanism 27 is provided at a position between the cassette storage unit 23 and the temporary placement table 25 and the sheet cutting table 26 in the X-axis direction. The first transport mechanism 27 movably supports a base 271 along a pair of guide rails 272 extending in the Y-axis direction, and moves the base 271 in the Y-axis direction by rotating a ball screw 273 extending in the Y-axis direction with the driving force of a motor. A robot hand 274 is supported on the base 271. The first transport mechanism 27 transports wafers W between the cassette 24 in the cassette storage unit 23 and the temporary placement table 25 and the sheet cutting table 26 by moving the base 271 in the Y-axis direction and operating the robot hand 274.

[0021] The holding table 21 is provided at a position away from the temporary placement table 25 and the sheet cutting table 26 in the +X direction. As shown in FIGS. 2, 4, 5, and 6, the holding table 21 has a disk-shaped holding plate 211 made of a light-transmitting material such as quartz glass, and a cylindrical frame member 212 that supports the periphery of the holding plate 211. The upper surface of the holding plate 211 forms a flat holding surface 22 on which the sheet 11 is placed. A hollow internal space 213 is formed inside the frame member 212, and the upper side of the internal space 213 is covered by the holding plate 211.

[0022] A light 28 is provided at the bottom of the internal space 213. The light 28 is a light source that irradiates ultraviolet light UV (see FIGS. 2 and 6) toward the upper side where the holding plate 211 is disposed, and irradiates the ultraviolet light UV through the light-transmitting holding plate 211 and sheet 11 onto the liquid resin 12 on the sheet 11 to harden it. The ultraviolet light UV emitted by the light 28 has a wavelength of about 200 nm to 400 nm.

[0023] 1, a second transport mechanism 29 for transporting a wafer W is provided at a position on the -Y direction side of the holding table 21, the temporary placement table 25, and the sheet cutting table 26. The second transport mechanism 29 movably supports a pedestal 291 along a pair of guide rails 292 extending in the X-axis direction, and moves the pedestal 291 in the X-axis direction by rotating a ball screw 293 extending in the Y-axis direction with the driving force of a motor. A robot hand 294 is supported on the pedestal 291. The second transport mechanism 29 transports the wafer W between the temporary placement table 25, the sheet cutting table 26, and the holding table 21 by moving the pedestal 291 in the X-axis direction and operating the robot hand 294.

[0024] As shown in FIG. 1, the apparatus includes a sheet supply mechanism 30 that supplies sheet 11 to holding table 21. Sheet supply mechanism 30 includes a sheet supply unit 31 that supports rolled sheet 11, and a sheet transport arm 32 that pulls out sheet 11 from sheet supply unit 31. Sheet transport arm 32 has a rectangular frame-like structure that includes a pair of parallel X-axis extension portions 321 extending in the X-axis direction and a pair of parallel Y-axis extension portions 322 extending in the Y-axis direction. One of Y-axis extension portions 322, located on the -X direction side, is provided with a sheet gripping portion 323 that grips the end of sheet 11 on the -X direction side.

[0025] The sheet transport arm 32 is moved in the X-axis direction by a transport arm drive mechanism 33. The transport arm drive mechanism 33 is configured with, for example, a ball screw mechanism or an air cylinder. The sheet transport arm 32 is moved in the -X direction by the transport arm drive mechanism 33, and the sheet 11 gripped by the sheet gripper 323 is pulled, thereby drawing out the sheet 11 from the sheet supply unit 31.

[0026] The sheet conveying arm 32 is provided with a sheet pressure roller 34 between a pair of Y-axis extensions 322, which is rotatable about an axis extending in the X-axis direction. The sheet pressure roller 34 is supported along the Y-axis extensions 322 so as to be movable in the Y-axis direction, and can be moved in the Y-axis direction by the force of a driving source such as a motor (not shown). The sheet conveying arm 32 is moved in the -X direction, and the sheet 11 is pulled out to a position covering the holding surface 22 of the holding table 21, and then the sheet pressure roller 34 is moved in the Y-axis direction. The sheet pressure roller 34 moves in the Y-axis direction while pressing the pulled-out sheet 11 from above toward the holding surface 22 with a predetermined force, thereby moving across the sheet 11 in the width direction. This movement of the sheet pressure roller 34 pushes out air from between the sheet 11 and the holding surface 22, causing the sheet 11 to adhere closely to the holding surface 22 without any gaps.

[0027] The sheet 11 is cut by a sheet cutter provided in the sheet supply mechanism 30 while it is placed on the holding surface 22. The sheet cutter moves in the Y-axis direction to cut the sheet 11, forming an end portion on the +X-direction side of the sheet 11 held on the holding table 21.

[0028] 2, 4, 5, and 6, the holding table 21 has a plurality of suction holes 214 formed in the upper surface of the frame member 212. The suction holes 214 are connected to a suction source 35. By operating the suction source 35, air is sucked through the suction holes 214 to apply negative pressure, and the sheet 11 placed on the holding surface 22 of the holding table 21 is held by suction.

[0029] The protective member forming device 20 includes a liquid resin supply mechanism 36 that supplies liquid resin 12 to the sheet 11 held by the holding table 21. The liquid resin supply mechanism 36 includes a tank 37 provided inside the protective member forming device 20, a dispenser 38 connected to the tank 37, and a liquid resin supply nozzle 39 connected to a supply pipe extending from the dispenser 38. The liquid resin 12 stored in the tank 37 is sent to the liquid resin supply nozzle 39 by the operation of the dispenser 38.

[0030] 1 and 4, the liquid resin supply nozzle 39 is provided on one Y-axis extension portion 322 located on the −X direction side of the sheet transport arm 32, and has a lower nozzle 391 facing downward and an upper nozzle 392 facing upward. The liquid resin supply mechanism 36 can individually control the supply of the liquid resin 12 from the lower nozzle 391 and the supply of the liquid resin 12 from the upper nozzle 392. The amount of liquid resin 12 supplied from each of the lower nozzle 391 and the upper nozzle 392 is controlled by the operation of the dispenser 38.

[0031] The liquid resin 12 discharged from the lower nozzle 391 is dripped onto the sheet 11 held on the holding table 21. The liquid resin 12 discharged from the upper nozzle 392 can be attached to the lower surface Wb of the wafer W held on the wafer holding table 40 described below. The liquid resin supply nozzle 39 may be configured to include only the lower nozzle 391 without including the upper nozzle 392. In other words, it is sufficient that the liquid resin 12 is supplied to at least the sheet 11, and it is not essential that the liquid resin 12 adhere to the lower surface Wb of the wafer W at the stage of supplying the liquid resin 12 to the sheet 11.

[0032] A wafer holding table 40 is disposed above the holding table 21. The wafer holding table 40 is supported movably in the Z-axis direction via an elevating mechanism 41 provided on a column 42 located on the -X-direction side of the holding table 21. The elevating mechanism 41 movably supports a lifting table 411 along a pair of guide rails 412 extending in the Z-axis direction, and moves the lifting table 411 in the Z-axis direction by rotating a ball screw 413 extending in the Z-axis direction with the driving force of a motor. The wafer holding table 40 and the lifting mechanism 41 constitute a bonding mechanism that bonds the sheet 11 held on the holding table 21 to the wafer W via the liquid resin 12.

[0033] The wafer holding table 40 is disk-shaped and supported on the lower end of a support member 43 that moves in the Z-axis direction together with the lift table 411. The wafer holding table 40 moves in the Z-axis direction as the lift mechanism 41 moves the lift table 411. As shown in FIGS. 2, 4, 5, and 6, a suction plate 44, which is a disk-shaped porous member, is provided on the underside of the wafer holding table 40. The underside of the suction plate 44 forms a wafer holding surface 441 that suction-holds the upper surface Wa of the wafer W. The suction plate 44 is connected to a suction source 45. By operating the suction source 45 to suck air from the suction plate 44 and apply a negative pressure, the upper surface Wa of the wafer W can be suction-held on the wafer holding surface 441.

[0034] A load sensor 46 is provided between the wafer holding table 40 and the support member 43 to detect the load acting on the wafer holding table 40 in the Z-axis direction.

[0035] A camera 47 is disposed to the side of the holding table 21. The camera 47 is disposed above the holding surface 22 of the holding table 21, and is capable of capturing an image of the sheet 11 held on the holding table 21 from an oblique direction. More specifically, the optical axis of the optical system of the camera 47 is set at a predetermined inclination with respect to a direction parallel to the holding surface 22 of the holding table 21 (horizontal direction), and the camera 47 captures an image of the sheet 11 on the holding table 21 from above at an angle. The camera 47 is equipped with an imaging element, and an image of the sheet 11 is formed by the optical system on the light receiving surface of the imaging element, and the imaging element generates an image signal in pixel units by photoelectric conversion.

[0036] The camera 47, which captures an image of the sheet 11 from an oblique direction, is disposed radially outward from the holding table 21. Therefore, the camera 47 can capture an image of the sheet 11 at a desired timing without affecting the operation of each part for forming the protective member 10, such as the operation of the sheet transport arm 32 in the sheet supply mechanism 30 and the operation of the wafer holding table 40, which is moved up and down by the lifting mechanism 41. Furthermore, since the camera 47 does not need to move directly above the holding table 21 to capture an image, no waiting time is required for capturing an image, and the protective member 10 can be efficiently formed.

[0037] The optical system of camera 47 has an angle of view that allows it to capture an image of the entire surface of sheet 11 held on holding surface 22 of holding table 21. Compared to capturing an image from a position directly facing sheet 11 in the Z-axis direction (directly above), camera 47, which captures an image of sheet 11 from an oblique direction, can capture an image that covers the entire surface of sheet 11 with an optical system with a relatively narrow angle of view, making it possible to use an optical system that is more versatile and readily available rather than an ultra-wide-angle lens (fisheye lens). Furthermore, camera 47, which captures an image of sheet 11 from an oblique direction, contains more information in the captured image than a camera that captures image of sheet 11 from directly beside it, making it possible to determine with high accuracy how much air is present in which parts of sheet 11. Note that sheet 11 may also be captured from directly beside it.

[0038] The protective member forming apparatus 20 is controlled by a control unit 50 (see FIG. 1). The control unit 50 is configured with a processor that executes various processes, a storage unit (memory) that stores various parameters and control programs, and the like. The storage unit of the control unit 50 stores a program for executing a method for forming a protective member, which will be described later, as part of the control program for the protective member forming apparatus 20. This program includes an algorithm for determining the presence or absence of air (air pockets) based on the image captured by the camera 47.

[0039] The control unit 50 has an image processing unit 51 and a judgment unit 52 as functional blocks. The image processing unit 51 receives an image signal from the image sensor of the camera 47, processes the image, and generates a captured image in a predetermined image format. The judgment unit 52 determines whether air is present between the holding table 21 and the sheet 11 based on the captured image generated by the image processing unit 51. Note that the functions of the image processing unit 51 and the judgment unit 52 are realized by the operation of the processor, memory, and other devices that constitute the control unit 50, and this does not mean that the image processing unit 51 and the judgment unit 52 are composed of only one independent electronic component. Furthermore, while FIG. 1 schematically shows only the connection between the camera 47 and the control unit 50, the control unit 50 is also connected to each unit of the protective member forming apparatus 20 other than the camera 47 so as to be able to send and receive signals.

[0040] The formation of the protective member 10 (protective member forming method) by the protective member forming apparatus 20 configured as above will be described. Unless otherwise specified, it is assumed that the operation is performed under the control of the control unit 50 in each of the following steps.

[0041] [Sheet supply process] In the sheet supply process, the sheet supply mechanism 30 is used to supply the sheet 11 to the holding table 21. The edge of the sheet 11 is gripped by the sheet gripping portion 323 of the sheet transport arm 32, and the transport arm drive mechanism 33 moves the sheet transport arm 32 in the −X direction to pull out the sheet 11 from the sheet supply unit 31. When the sheet 11 is pulled out to a position where it covers the holding surface 22 of the holding table 21, the movement of the sheet transport arm 32 by the transport arm drive mechanism 33 is stopped.

[0042] [Sheet holding process] Next, a sheet holding process is performed in which the sheet 11 is held on the holding table 21. In the sheet holding process, the sheet pressure roller 34 is moved in the Y-axis direction over the pulled-out sheet 11, and the sheet pressure roller 34 presses the sheet 11 against the holding table 21, thereby removing air from between the sheet 11 and the holding surface 22. The suction source 35 is also operated to suck air through the suction holes 214, and the sheet 11 is suction-held on the holding surface 22 of the holding table 21. Through the above operations, the sheet 11 is held on the holding table 21. Then, the edge of the sheet 11 held on the holding table 21 on the +X direction side is cut using a sheet cutter provided in the sheet supply mechanism 30.

[0043] In the sheet holding process, when the sheet 11 is properly held on the holding table 21, the operation of the sheet pressure roller 34 pushes out air from between the sheet 11 and the holding surface 22, and the entire underside of the sheet 11 is tightly attached to the holding surface 22 of the holding table 21 without any gaps. However, when the holding table 21 holds the sheet 11, due to factors such as dust adhering to the holding surface 22 of the holding table 21 or the underside of the sheet 11, air may become trapped between the holding surface 22 and the sheet 11 even when pressure is applied by the sheet pressure roller 34.

[0044] If the protective member 10 is formed while there is an air pocket between the holding surface 22 of the holding table 21 and the sheet 11, the protective member 10 will be thin at the air pocket, resulting in an uneven thickness of the protective member 10. If the wafer W is ground while the protective member 10 has an uneven thickness, the ground wafer W will have an uneven in-plane thickness. Therefore, in order to form the protective member 10 without creating an air pocket between the holding table 21 and the sheet 11, the protective member forming apparatus 20 performs an imaging process of imaging the sheet 11 with a camera 47 and a determination process of determining whether or not there is air (an air pocket) between the holding table 21 and the sheet 11 based on the image captured in the imaging process. The imaging process and the determination process are performed after the sheet 11 is supplied to the holding table 21 and held on the holding surface 22 in the sheet supplying process and the sheet holding process, and before the liquid resin 12 is supplied onto the sheet 11 to form the protective member 10.

[0045] [Imaging process] FIG. 2 shows a state in which an imaging process of imaging the sheet 11 with a camera 47 and a determination process of determining whether air is present between the holding table 21 and the sheet 11 are being performed. In the imaging process, ultraviolet light UV is irradiated from a light 28 provided in the internal space 213 of the holding table 21 toward the holding plate 211 and the sheet 11 above. In this state, the sheet 11 on the holding table 21 is imaged by the camera 47, and an image is generated through image processing by an image processing unit 51. Because the holding plate 211 and the sheet 11 are both made of a translucent material, when the holding plate 211 and the sheet 11 are illuminated from below by ultraviolet light UV emitted from the light 28 and the sheet 11 is imaged from diagonally above by the camera 47, an image in which the sheet 11 has a predetermined brightness and color tone can be obtained. Note that, because the ultraviolet-curable liquid resin 12 has not yet been supplied onto the sheet 11 at the time of the imaging process, irradiation of ultraviolet light UV from the light 28 does not have the effect of hardening the liquid resin 12.

[0046] [Judgment process] If air is present between the holding table 21 and the sheet 11, differences in the image, such as differences in color tone, brightness, or color, will occur between areas where air is present and areas where air is not present in the captured image. In the determination process, the determination unit 52 of the control unit 50 uses this information on color tone, brightness, or color to determine whether or not air is present between the holding table 21 and the sheet 11 based on the captured image captured by the camera 47. Note that, unlike in FIG. 2, irradiation of ultraviolet light UV from the light 28 may be stopped in the determination process.

[0047] 3 shows an example of a captured image when air is present between the holding table 21 and the sheet 11. The color tone of the image captured by the camera 47 and the appearance of the area where air is present in the image vary depending on conditions such as the position of the light source and the wavelength of the light emitted by the light source. The control unit 50 stores a control program that enables the determination unit 52 to perform image determination of the captured image according to these conditions.

[0048] 3 is an image captured by camera 47 from an oblique direction, showing a state in which holding plate 211 and sheet 11 are illuminated from below by light 28 emitting ultraviolet light UV. In image 60, a first region 61 corresponds to a location where holding table 21 and sheet 11 are in close contact with each other without any air pockets, and a second region 62 corresponds to a location where air pockets exist between holding table 21 and sheet 11. In image 60, first region 61 is dark blue, and elliptical second region 62 is light blue. By capturing an image of sheet 11 from an oblique direction using camera 47, an image can be obtained in which there is a difference in brightness (color density) between locations where no air has entered and locations where air is present.

[0049] Based on information that the captured image 60 contains a first region 61 and a second region 62 with different brightness levels, the determination unit 52 determines that an air pocket exists between the holding table 21 and the sheet 11 in the high-brightness second region 62. As a criterion for determination by the determination unit 52, for example, a threshold value for brightness can be set, and it can be determined that air exists in a portion of the captured image whose brightness exceeds the threshold (high brightness). If there is no air pocket between the holding table 21 and the sheet 11, the entire captured image 60 will be the dark blue first region 61, and because the brightness of the first region 61 is equal to or less than the threshold, it is determined that no air has entered between the entire surface of the sheet 11 and the holding table 21.

[0050] The light 28 is used in the curing process described below to cure the liquid resin 12, which is an ultraviolet curable resin. In this way, by utilizing the light 28 used for curing in the curing process as a light source for imaging in the imaging process, the number of parts can be reduced and the device configuration can be simplified.

[0051] The light used as the light source for imaging in the imaging process is not limited to the light 28 that is arranged inside the holding table 21 and irradiates ultraviolet light UV from below. For example, it is also possible to use the light (ambient light) from the room lighting that illuminates the clean room in which the protective member forming device 20 is installed as the light source, and to perform imaging with the camera 47 using light irradiated from outside the holding table 21 in the imaging process. Many of these types of room lights emit white light that includes all wavelengths of visible light.

[0052] 3 is an image captured by camera 47 from an oblique direction, showing a state in which sheet 11 on holding table 21 is illuminated by white light emitted from a room light (not shown) placed outside holding table 21. In image 63, a first region 64 is a location where holding table 21 and sheet 11 are in close contact with each other without any air pockets, and a second region 65 is a location where air pockets exist between holding table 21 and sheet 11. In image 63, first region 64 is transparent. Second region 65 is striped and includes, from the outside, an elliptical ring-shaped blue outer edge region 651, an elliptical ring-shaped green middle region 652, and an elliptical transparent inner region 653.

[0053] The determination unit 52 determines that an air pocket exists in the second region 65 based on information such as the color difference (difference in color tone) between the first region 64 and the second region 65 of the captured image 63, and the striped pattern formed in the second region 65 by the outer edge region 651, the middle region 652, and the inner region 653. If there is no air pocket between the holding table 21 and the sheet 11, the entire captured image 63 becomes the transparent first region 64, and no color difference or particular pattern appears, so it is determined that no air has entered between the entire surface of the sheet 11 and the holding table 21.

[0054] In the determination step, if the determination unit 52 determines that air (air pocket) exists between the holding table 21 and the sheet 11, the control unit 50 performs a predetermined countermeasure so as to prevent the formation of the protective member 10 while air remains. The following countermeasure may be performed independently or in combination with a plurality of countermeasures.

[0055] [Countermeasures: Sheet re-holding process] As an example of the countermeasure processing, a sheet re-holding process can be performed. In the sheet re-holding process, the control unit 50 controls the sheet supply mechanism 30 to temporarily remove the sheet 11 determined to have air intrusion from the holding table 21, and then operate the sheet conveying arm 32 and the sheet pressure roller 34 to hold (re-place) the sheet 11 on the holding table 21 again. Then, the imaging process and the determination process are performed again. If the cause of air intrusion between the holding table 21 and the sheet 11 is not due to dust adhering to the underside of the sheet 11 or the holding surface 22 of the holding table 21, there is a possibility that the air intrusion will be eliminated by re-placing the sheet 11 in this way.

[0056] When the sheet 11 is to be repositioned, the operation of the sheet supply mechanism 30 may be controlled so that the sheet gripping unit 323 continues to grip the sheet 11 during the imaging process and the judgment process, and the sheet conveying arm 32 operates to quickly reposition the sheet 11. Note that when the edge of the sheet 11 is gripped by the sheet gripping unit 323, the vicinity of that edge of the sheet 11 floats above the holding surface 22 of the holding table 21, but this can be addressed by setting the program so that the judgment unit 52 judges that the difference in color tone, brightness, or color difference in the captured image caused by the lifting of the vicinity of the edge of the sheet 11 does not correspond to the intrusion of air.

[0057] If dust is attached to the underside of sheet 11 or holding surface 22 of holding table 21, air may again accumulate where the dust is attached, even if sheet 11 is replaced on holding table 21. If the air presence does not disappear even after repeating the imaging step, determination step, and sheet re-holding step a predetermined number of times, control unit 50 discards sheet 11 and controls sheet supply mechanism 30 to perform the sheet supply step and sheet holding step again to hold a new sheet 11 on holding table 21.

[0058] [Countermeasures: Garbage removal process] If the cause of air entering between the holding table 21 and the sheet 11 is dust adhering to the holding surface 22 of the holding table 21, the air may not be eliminated even if a new sheet 11 is supplied and held on the holding table 21. In such a case, the control unit 50 may execute a dust removal process to remove the dust on the holding table 21.

[0059] As an example of a process for removing dust on the holding table 21 in the dust removal process, the protective member forming apparatus 20 is equipped with a foreign matter removal mechanism capable of removing foreign matter on the holding table 21. If the determination unit 52 determines in the determination process that air is present between the holding table 21 and the sheet 11, the control unit 50 operates the sheet supply mechanism 30 to remove the sheet 11 from the holding table 21 and then uses the foreign matter removal mechanism to clean the holding surface 22. The foreign matter removal mechanism may be configured, for example, with an air blower that blows high-pressure air to blow away foreign matter, or a cleaning brush that moves horizontally while in contact with the holding surface 22. Removing the dust on the holding table 21 that causes air pockets can prevent the recurrence of air pockets.

[0060] [Countermeasure processing: Notification process] When the determination unit 52 determines that air is present between the holding table 21 and the sheet 11 in the determination step, one of the countermeasures is to perform a notification step of notifying the worker operating the protective member forming apparatus 20. In the notification step, the notification unit notifies the worker of the presence of air intrusion. As shown in FIG. 1 , the protective member forming apparatus 20 includes a display 70, a lamp 71, a speaker 72, and the like as the notification unit. The display 70 can display various information related to the protective member forming apparatus 20. In the notification step, the control unit 50 displays information that air is present between the holding table 21 and the sheet 11 on the display 70 using characters, icons, or the like. The lamp 71 can emit light in multiple colors, and the light emission method can be changed to continuous lighting, flashing, or the like. In the notification step, the control unit 50 causes the lamp 71 to emit light in a specific color or light emission method. In the notification step, the control unit 50 also notifies the worker by emitting a voice or warning sound from the speaker 72. The notification may be made using only one of the display 70, the lamp 71, and the speaker 72, or two or more of them may be used in combination. The notification unit used in the notification process is not limited to one provided in the protective member forming apparatus 20. For example, the notification unit may be installed in an external electronic device (a personal computer, a tablet-type electronic terminal) that can communicate with the protective member forming apparatus 20.

[0061] Upon receiving the notification from the notification unit, the worker checks the status of the protective member forming apparatus 20 and takes appropriate measures depending on the cause of the air intrusion. For example, if dust is found on the holding table 21 or the sheet 11, the worker instructs the protective member forming apparatus 20 to perform a dust removal operation using a foreign matter removal mechanism, causing the protective member forming apparatus 20 to execute the dust removal process described above. Furthermore, if air has entered but no dust is found on the holding table 21 or the sheet 11, the worker may cause the protective member forming apparatus 20 to execute the sheet re-holding process described above. Furthermore, if the presence of air between the holding table 21 and the sheet 11 persists even after performing operations corresponding to the dust removal process or the sheet re-holding process, the worker may perform maintenance work, such as replacing the holding table 21. In this way, if the determination unit 52 determines that air is present, the worker is notified by the notification unit, allowing the worker to take appropriate action depending on the situation.

[0062] If the determination unit 52 determines that air is present between the holding table 21 and the sheet 11, the control unit 50 may automatically execute the sheet re-holding process or the dust removal process, and the notification unit may notify the worker that air is present. In this case, the worker who receives the notification checks whether the situation has improved as a result of the sheet re-holding process or the dust removal process.

[0063] Through the determination by the determination unit 52 and corrective action based on the determination result, the supply of the sheet 11 to the holding table 21 can be completed without any air pockets between the holding table 21 and the sheet 11. The determination unit 52 determines that there is no air pocket between the holding table 21 and the sheet 11 based on the image captured by the camera 47, which means that the above corrective action is not necessary. If the determination step is performed while the sheet gripping unit 323 continues to grip the sheet 11, the sheet gripping unit 323 releases the grip of the sheet 11 upon completion of the determination step. If it is determined in the determination step that there is no air pocket between the holding table 21 and the sheet 11, the process proceeds to a protective member forming step in which the protective member 10 is formed by adhering the sheet 11 to the wafer W. The protective member forming step includes an expanding step and a curing step.

[0064] [Wafer holding process] Before the protective member forming step, a wafer holding step is performed in which the wafer W is held on the wafer holding table 40. At least a part of the wafer holding step may be performed in parallel (simultaneously) with at least one of the sheet supply step, the sheet holding step, the imaging step, and the determination step. For example, at the stage in FIG. 2 corresponding to the imaging step and the determination step, the wafer W is already held on the wafer holding table 40.

[0065] In the wafer holding process, the wafer W, before the protective member 10 is formed, is removed from the cassette 24 in the cassette storage unit 23 by the first transport mechanism 27 and transported to the temporary placement table 25. At the temporary placement table 25, the orientation and center of the wafer W are detected by the wafer detection unit 251. Once the orientation and center of the wafer W have been detected, the second transport mechanism 29 transports the wafer W to the wafer holding table 40. The wafer holding table 40 operates the suction source 45 to suction-hold the upper surface Wa of the wafer W onto the wafer holding surface 441 of the suction plate 44.

[0066] [Protective material forming process: expansion process] When the sheet 11 is held on the holding table 21 without any air between the holding table 21 and the sheet 11, and the wafer W is held by the wafer holding table 40, the process proceeds to the expanding step shown in FIGS. 4 and 5. In the expanding step, first, as shown in FIG. 4, liquid resin 12 is supplied between the sheet 11 and the wafer W. Specifically, the position of the sheet conveying arm 32 in the X-axis direction is adjusted by the conveying arm driving mechanism 33, and the liquid resin supply nozzle 39 is positioned above the sheet 11 held on the holding surface 22 of the holding table 21 in the previous sheet holding step. At this stage, the lower nozzle 391 of the liquid resin supply nozzle 39 faces the upper surface of the sheet 11, and the upper nozzle 392 faces the lower surface Wb of the wafer W.

[0067] Next, the control unit 50 controls the dispenser 38 to deliver the liquid resin 12 in the tank 37 to the liquid resin supply nozzle 39. The liquid resin supply mechanism 36 can individually supply the liquid resin 12 from the lower nozzle 391 and the upper nozzle 392 of the liquid resin supply nozzle 39. The liquid resin 12 is dripped from the lower nozzle 391 of the liquid resin supply nozzle 39 toward the sheet 11 below. The lower nozzle 391 is positioned above and near the center of the holding table 21, and the liquid resin 12 dripped from the lower nozzle 391 accumulates near the center of the upper surface of the sheet 11 in an area narrower than the area of ​​the wafer W. The liquid resin 12 supplied to the upper nozzle 392 forms a dome shape. When the wafer W is brought closer to the liquid resin supply nozzle 39 by the operation of the lifting mechanism 41, the dome-shaped liquid resin 12 at the upper nozzle 392 adheres to the lower surface Wb of the wafer W. Note that the liquid resin 12 may be dripped from the lower nozzle 391 onto the sheet 11 without being supplied to the upper nozzle 392.

[0068] Based on information such as the size of the wafer W, the control unit 50 supplies the liquid resin 12 to the sheet 11 and the underside Wb of the wafer W in an amount sufficient to cover the entire underside Wb of the wafer W. After the supply of the predetermined amount of liquid resin 12 is completed, the control unit 50 moves the sheet transport arm 32 in the +X direction by the transport arm drive mechanism 33, and removes the sheet transport arm 32 from between the holding table 21 and the wafer holding table 40.

[0069] 5, the liquid resin 12 is spread between the sheet 11 and the wafer W. Specifically, the wafer holding table 40 is lowered at a predetermined feed rate by the lifting mechanism 41. As the wafer holding table 40 is lowered, the lower surface Wb of the wafer W approaches the holding table 21 and comes into contact with the liquid resin 12 on the sheet 11. Then, the lower surface Wb of the wafer W presses against the liquid resin 12, spreading the liquid resin 12 in the radial direction of the wafer W.

[0070] As the wafer holding table 40 is lowered and the liquid resin 12 is spread by the underside Wb of the wafer W, the load applied to the underside Wb of the wafer W in the Z-axis direction (vertical direction) increases. When the liquid resin 12 spreads over the entire underside Wb of the wafer W and begins to spill out from the outer edge of the wafer W as shown in FIG. 5, the load begins to decrease. This change in load is detected by the load sensor 46. Based on the detection result by the load sensor 46, the control unit 50 detects that the liquid resin 12 has spread over the entire underside Wb of the wafer W. When this state is detected, the control unit 50 stops the lowering of the wafer holding table 40. At this stage, the spreading process is completed.

[0071] Alternatively, the distance between the holding table 21 and the wafer holding table 40 may be set in advance, and the wafer holding table 40 may be lowered to that distance to complete the expansion step.

[0072] [Protective material forming process: hardening process] Once the spreading step is completed and the entire lower surface Wb of the wafer W is covered with the liquid resin 12, the curing step begins. As shown in FIG. 6 , in the curing step, under the control of the control unit 50, the suction holding of the upper surface Wa of the wafer W to the wafer holding surface 441 (negative pressure due to the operation of the suction source 45) is stopped, the wafer W held by the wafer holding table 40 is released, and the lifting mechanism 41 is operated to raise the wafer holding table 40. Then, ultraviolet light UV having an intensity sufficient to harden the liquid resin 12 is irradiated from the light 28 toward the holding surface 22. The ultraviolet light UV emitted from the light 28 passes through the light-transmitting holding plate 211 and sheet 11 to reach the liquid resin 12 and harden the liquid resin 12, which is an ultraviolet-curable resin. The control unit 50 determines the curing state of the liquid resin 12 based on the passage of a predetermined time and the analysis results of an image of the liquid resin 12 captured by the camera 47, and when it is determined that the liquid resin 12 has sufficiently cured, it stops the irradiation of the ultraviolet light UV from the light 28. As a result, the sheet 11 is adhered to the wafer W via the resin 13 that has cured the liquid resin 12, and the sheet 11 and the cured resin 13 form the protective member 10.

[0073] As described above, the protective member forming process involves an expansion process in which the liquid resin 12 supplied between the sheet 11 and the wafer W is expanded over the entire surface of one side of the wafer W, and a hardening process in which the liquid resin 12 expanded by the expansion process is hardened, and the sheet 11 is then attached to the wafer W via the hardened resin 13.

[0074] [Post-processing process] Once the protective member 10 is formed, a post-processing step is executed under the control of the control unit 50. In the post-processing step, the wafer W on which the protective member 10 has been formed is transferred from the wafer holding table 40 to the robot hand 294 of the second transport mechanism 29, and is transported by the second transport mechanism 29 to the sheet cutting table 26. The wafer W is held on the sheet cutting table 26, and the excess outer edge region of the sheet 11 that protrudes from the wafer W is cut off using the sheet cutter 261. Next, the first transport mechanism 27 stores the wafer W in the cassette 24 of the cassette storage unit 23. This completes the series of processes for the wafer W in the protective member forming apparatus 20.

[0075] As described above, in the protective member forming apparatus 20, the sheet 11 held on the holding table 21 is illuminated by the light 28 (or a light disposed in a different location from the light 28), and the camera 47 captures an image of the sheet 11 from an oblique direction. The determination unit 52 determines whether air is present between the holding table 21 and the sheet 11 based on a determination criterion based on color tone, brightness, or color difference in the image captured by the camera 47. If it determines that no air has entered, the liquid resin 12 is supplied between the sheet 11 and the wafer W, and the liquid resin 12 is expanded and cured to bond the sheet 11 to the wafer W, thereby forming the protective member 10. If the determination unit 52 determines that air is present, the notification unit (e.g., the display 70, the lamp 71, the speaker 72, etc.) notifies the operator. In this way, the liquid resin 12 is supplied after checking for the presence or absence of air between the holding table 21 and the sheet 11, thereby preventing the formation of a protective member 10 with a partially thin thickness due to air entering. As a result, the protective member 10 formed by the protective member forming apparatus 20 does not have local variations in thickness caused by air pockets between the holding table 21 and the sheet 11, and can achieve a uniform thickness throughout.

[0076] The presence or absence of air between the holding table 21 and the sheet 11 is determined based on an image of the sheet 11 captured by the camera 47, so there is no need to install any special sensors other than the camera 47, which reduces implementation costs. Furthermore, since the camera 47 captures an image from an oblique direction that captures the entire sheet 11 (including at least the area to be attached to the wafer W), the time required to determine the presence or absence of air is short, and the formation of the protective member 10 by the protective member forming apparatus 20 can be efficiently carried out.

[0077] After the protective member 10 is formed, the wafer W is transported to a grinding device (not shown). In the grinding device, the wafer W is placed on the holding surface of a chuck table with the protective member 10 facing downward, and a grinding wheel is brought into contact with the upper surface Wa of the wafer W to perform grinding. As described above, the protective member 10 formed by the protective member forming device 20 has a uniform thickness throughout because it is formed on the holding table 21 without air entering the underside of the sheet 11. This eliminates the risk of deterioration in the grinding accuracy of the wafer W due to variations in the thickness of the protective member 10, and makes it possible to uniform the in-plane thickness of the wafer W ground to the desired thickness. In other words, wafers W with a uniform thickness can be manufactured by grinding.

[0078] The arrangement and configuration of the cameras that capture images of the sheet in the protective member forming apparatus may be different from those in the above embodiment. For example, while the protective member forming apparatus 20 in the above embodiment is provided with the camera 47 in one location, multiple cameras may be arranged at predetermined intervals around the circumferential direction of the holding table 21, and the presence or absence of air between the holding table 21 and the sheet 11 may be determined based on multiple images captured by the multiple cameras.

[0079] As a modified example, a camera can be installed in the internal space 213 of the holding table 21. For example, if a camera is installed in the internal space 213 at a position on the outermost edge close to the inner circumferential surface of the frame member 212, most of the area of ​​the sheet 11 that is to be attached to the wafer W can be imaged from diagonally below through the light-transmitting holding plate 211. As another configuration example, a camera equipped with an ultra-wide-angle lens (fisheye lens) can be installed near the center in the radial direction of the bottom of the internal space 213. If an image of the sheet 11 is taken using the ultra-wide-angle lens with a camera installed near the center of the bottom of the internal space 213, the area near the outer periphery of the sheet 11 will be imaged from an oblique direction relative to the sheet 11, and an image that can be used to determine the presence or absence of air in the determination step can be obtained.

[0080] Using a camera 47 that captures an image of sheet 11 from an oblique direction has the advantages described above. However, even in an image captured by a camera directly above or beside sheet 11, differences in color tone, brightness, or color occur between areas where air is present and areas where air is not present, making it possible to determine whether air is present between holding table 21 and sheet 11. In other words, the camera is not limited to one that captures an image of sheet 11 from an oblique direction. When using a camera that captures an image of sheet 11 from directly above, for example, the camera can be supported so as to be movable horizontally, positioned directly above holding table 21, and imaged of sheet 11, and then retracted to a position outside holding table 21 once the image capture is complete.

[0081] The embodiments of the present invention are not limited to the above-described embodiments and modifications, and may be variously changed, substituted, or modified without departing from the spirit of the technical idea of ​​the present invention. Furthermore, if the technical idea of ​​the present invention can be realized in a different way due to technological advances or other derived technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical idea of ​​the present invention. [Industrial Applicability]

[0082] As described above, according to the protective member forming device and protective member forming method of the present invention, by checking whether or not there is air between the holding table and the sheet, it is possible to form a protective member of uniform thickness without creating air pockets between the holding table and the sheet, thereby improving the processing accuracy of grinding processes and other processes performed on wafers with the protective member in place. [Explanation of symbols]

[0083] 10: Protective material 11: Sheet 12: Liquid resin 13: Hardened resin 20: Protective member forming device 21: Holding table 22: Holding surface 27: First transport mechanism 28: Light 29: Second transport mechanism 30: Sheet supply mechanism 32: Sheet transport arm 34: Sheet pressure roller 36: Liquid resin supply mechanism 38: Dispenser 39: Liquid resin supply nozzle 40: Wafer holding table (adhesion mechanism) 41: Lifting mechanism (adhesion mechanism) 44: Suction plate 47: Camera 50: Control unit 51: Image processing unit 52: Judgment Department 60: Image capture 61: 1st area 62:Second area 63: Image capture 64: 1st area 65:Second area 70: Display (notification section) 71: Lamp (notification section) 72: Speaker (notification section) UV: Ultraviolet light W: wafer

Claims

1. A protective member forming apparatus including: a holding table that holds a sheet by a holding surface; a sheet supply mechanism that supplies the sheet to the holding table; and an adhering mechanism that adheres the sheet held on the holding table to a wafer, a light for illuminating the sheet held on the holding table; a camera for capturing an image of the sheet; a determining unit that determines whether air is present between the holding table and the sheet based on differences in color tone, brightness, or color difference in the image captured by the camera.

2. 2. A method for forming a protective member on one surface of a wafer by using the protective member forming apparatus according to claim 1, comprising: a sheet holding step of holding the sheet on the holding table; an imaging step of imaging the sheet with the camera; a determining step of determining whether air exists between the holding table and the sheet based on a difference in color tone, brightness, or color difference in the image captured in the imaging step; a notification step of notifying an operator by a notification unit if it is determined in the determination step that air is present, or a protective member forming step of forming a protective member that protects one surface of the wafer by adhering the sheet to the wafer if it is determined in the determination step that no air is present. A method for forming a protective member.

3. The protective member forming step includes: a spreading step of supplying a liquid resin between the sheet and the wafer and spreading the liquid resin over the entire surface of one side of the wafer; a curing step of curing the liquid resin expanded by the expanding step, The sheet is adhered to the wafer via the resin obtained by hardening the liquid resin. The method for forming the protective member according to claim 2.

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