JP2024102422A - Protective film forming apparatus, judgment method, and protective film forming method - Google Patents

Abstract

[Problem] To provide a protective film forming device that can appropriately determine whether or not resin pieces are attached to the holding surface of a holding table. [Solution] The protective film forming device includes a holding table, a protective film forming unit, a light source, an imaging unit, a cleaning unit, and a controller. The controller causes the light source to emit light when the holding surface of the holding table is not holding a workpiece, and while the light source is emitting light, causes the imaging unit to capture an image of the holding surface when no workpiece is being held, obtaining an image of the holding surface, and determines whether or not resin pieces containing resin are attached to the holding surface based on the image. [Selected Figure] Figure 3

Description

The present invention relates to a protective film forming device used when forming a protective film containing a resin on a workpiece, a determination method used in the protective film forming device, and a protective film forming method including the determination method.

As a method for dividing a plate-shaped workpiece such as a semiconductor wafer into multiple chips, a processing method called laser ablation is known in which the workpiece is irradiated with a laser beam to partially melt and evaporate the irradiated area (see, for example, Patent Document 1). In this laser ablation method, parts of the workpiece that are melted and evaporated by the laser beam scatter into the surrounding area and become debris (processing waste), which tends to adhere to the top surface of the workpiece, etc.

In recent years, a processing method has been proposed in which a water-soluble protective film is formed on the top surface of the workpiece, and the workpiece is irradiated with a laser beam through this protective film (see, for example, Patent Document 2). In this processing method, debris generated by laser ablation adheres to the protective film and is washed away together with the protective film in a subsequent cleaning process, reducing the possibility of debris adhering to the top surface, etc., of the workpiece.

Japanese Patent Application Publication No. 6-120334 JP 2006-140311 A

When forming a water-soluble protective film on the top surface of a workpiece, for example, a protective film forming device is used that includes a holding table that has a holding surface that holds the bottom side of the workpiece and is connected to a rotary drive source, and a nozzle that supplies liquid resin, which is the raw material for the protective film, to the top surface of the workpiece. Liquid resin is dropped onto the workpiece from the nozzle, and the holding table together with the workpiece is rotated by the rotary drive source to spread the liquid resin thinly, and this liquid resin is dried, forming a water-soluble protective film on the top surface of the workpiece.

However, liquid resin can adhere to the holding surface of the holding table mentioned above for various reasons, and when this liquid resin dries, pieces of resin can remain on the holding surface. If the underside of the workpiece is held by a holding table with pieces of resin remaining on the holding surface, the top surface of the workpiece will tilt, and a protective film of uniform thickness will not be formed. If the uniformity of the thickness of the protective film decreases, the workpiece will not be adequately protected during laser ablation.

Therefore, the object of the present invention is to provide a protective film forming device that can properly determine whether or not resin pieces are attached to the holding surface of a holding table, a determination method used in this protective film forming device, and a protective film forming method that includes this determination method.

According to one aspect of the present invention, a protective film forming device for forming a protective film containing resin on a first surface of a workpiece having a first surface and a second surface opposite to the first surface includes a holding surface for holding the second surface of the workpiece and a holding table connected to a rotary drive source, a resin supply nozzle for supplying liquid resin as a raw material for the protective film, and a protective film forming unit for applying the liquid resin to the first surface of the workpiece held by the holding surface of the holding table to form the protective film, a light source for emitting light from above the holding surface of the holding table toward the holding surface, an imaging unit having a light receiving element and imaging the holding surface side of the holding table from above the holding surface of the holding table to form an image, and a cleaning device. The protective film forming device includes a cleaning unit that has a cleaning nozzle that supplies a fluid and cleans the holding surface of the holding table, and a controller that has a processing device and a storage device and controls the operation of the light source and the imaging unit by operating the processing device according to a program stored in the storage device, and the controller, according to the program, causes the light source to radiate the light when the holding surface of the holding table is not holding the workpiece, and causes the imaging unit to capture an image of the holding surface when the light source is radiating the light, and determines whether or not resin pieces containing the resin are attached to the holding surface based on the image.

Preferably, the light source emits light of a wavelength that is absorbed by the protective film, and the light receiving element of the imaging unit is sensitive to the wavelength of light emitted by the protective film that has absorbed the light. Also, preferably, when it is determined that the resin piece is attached to the holding surface, the controller causes the cleaning unit to clean the holding surface according to the program.

According to another aspect of the present invention, there is provided a method for determining whether or not a resin piece, including a resin contained in a protective film of a workpiece, is attached to the holding surface of a holding table having a holding surface for holding a workpiece, the method comprising: emitting light from a light source above the holding surface toward the holding surface when the holding surface of the holding table is not holding the workpiece; capturing an image of the holding surface when the light source is emitting the light using an imaging unit; and determining whether or not the resin piece is attached to the holding surface based on the image.

Preferably, the light source emits light of a wavelength that is absorbed by the protective film, and the imaging unit has a light receiving element that is sensitive to the wavelength of light emitted by the protective film that has absorbed the light. Also, preferably, when it is determined that the resin pieces are attached to the holding surface, the holding surface is cleaned by a cleaning unit.

According to yet another aspect of the present invention, there is provided a protective film forming method including the above-mentioned determination method, in which, when it is determined that the resin pieces are attached to the holding surface and after the holding surface has been cleaned by the cleaning unit, or when it is determined that the resin pieces are not attached to the holding surface, the second surface of the workpiece having a first surface and a second surface opposite to the first surface is held by the holding surface of the holding table, and a liquid resin that is a raw material for the protective film is applied to the first surface of the workpiece held by the holding surface of the holding table to form the protective film.

In one aspect of the present invention, a protective film forming device or the like emits light from a light source above the holding surface of a holding table toward the holding surface when the holding surface is not holding a workpiece, then has an imaging unit capture an image of the holding surface when the holding surface is not holding a workpiece, and then determines whether or not resin pieces are attached to the holding surface based on the image, thereby making it possible to appropriately determine whether or not resin pieces are attached to the holding surface of the holding table.

FIG. 1 is a perspective view of a laser processing apparatus on which a protective film forming device is mounted. FIG. 2 is a perspective view of the protective film forming apparatus. FIG. 3 is a cross-sectional view of the protective film forming apparatus. FIG. 4 is a flowchart of a determination method used in the protective film forming apparatus and a protective film forming method including the determination method. FIG. 5 is a cross-sectional view showing a state in which the upper surface of the holding table is exposed. FIG. 6 is a cross-sectional view showing a state in which light is emitted from the light source toward the upper surface of the holding table. FIG. 7 is a cross-sectional view showing how light emitted from a resin piece adhering to the upper surface of the holding table is detected by the imaging unit. FIG. 8 is a diagram showing an example of an image showing the top surface of the holding table. FIG. 9 is a cross-sectional view showing a state in which the upper surface of the holding table has been cleaned and the resin pieces have been removed. FIG. 10 is a cross-sectional view showing how a protective film is formed on a workpiece.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a laser processing device 2 on which a protective film forming device 46 of this embodiment is mounted. For ease of explanation, some elements of the laser processing device 2 are omitted from FIG. 1. In addition, the X-axis (processing feed axis), Y-axis (indexing feed axis), and Z-axis (vertical axis) used in the following explanation are mutually perpendicular.

As shown in FIG. 1, the laser processing device 2 includes a base 4 that supports multiple elements. A columnar or wall-shaped support structure 6 is disposed at an end portion of the base 4 located on one side (rear side) along the Y axis. A storage section 4a is disposed at a corner portion of the base 4 on the other side (front side) along the Y axis and on one side along the X axis.

An opening is formed on the top surface of the storage section 4a. Inside the storage section 4a, a space is formed that is connected to the outside through the opening on the top surface, and contains a cassette support table 8 with a generally flat top surface and a lifting mechanism (not shown) that raises and lowers the cassette support table 8. A cassette 10 capable of holding multiple workpieces 11 is placed on the top surface of the cassette support table 8 exposed from the opening of the storage section 4a.

The workpiece 11 is typically a disk-shaped semiconductor wafer made of a semiconductor such as silicon (Si), and has a circular first surface 11a and a circular second surface 11b opposite the first surface 11a. For example, the first surface 11a of the workpiece 11 is partitioned into a number of small regions by a number of mutually intersecting straight lines (streets) intended for processing, and a device such as an IC (Integrated Circuit) is formed in each small region.

A tape (dicing tape) 13 having a diameter larger than that of the workpiece 11 is attached to the second surface 11b side of the workpiece 11. In addition, a ring-shaped frame 15 is fixed to the outer edge of the tape 13 so as to surround the workpiece 11. In this way, in the laser processing device 2 of this embodiment, the workpiece 11 is processed while being supported by the frame 15 via the tape 13.

In this embodiment, a disk-shaped semiconductor wafer made of a semiconductor such as silicon is used as the workpiece 11, but there are no restrictions on the material, shape, structure, size, etc. of the workpiece 11. For example, a substrate made of other semiconductors, ceramics, resin, metal, etc. may be used as the workpiece 11. Similarly, there are no restrictions on the type, number, shape, structure, size, arrangement, etc. of devices. The workpiece 11 does not necessarily have to have a device formed thereon. In addition, the workpiece 11 does not necessarily have to be supported by the frame 15 via the tape 13.

In the rear area of the storage section 4a, an alignment mechanism 12 capable of aligning the frame 15 supporting the workpiece 11 is disposed. The alignment mechanism 12 includes, for example, a pair of guide rails 12a, 12b that move toward and away from each other while remaining generally parallel to the Y-axis. Each of the guide rails 12a, 12b has a bottom surface that supports the frame 15 and a side surface perpendicular to the bottom surface.

For example, the frame 15 removed from the cassette 10 is placed on the guide rails 12a, 12b of the alignment mechanism 12, and the frame 15 is sandwiched between the pair of guide rails 12a, 12b in the direction along the X-axis, thereby aligning the frame 15 (i.e., the workpiece 11) to a predetermined position. A transport mechanism 14 for transporting the frame 15 is disposed above the alignment mechanism 12.

A moving mechanism (processing feed mechanism, indexing feed mechanism) 16 is disposed in a region to the side of the alignment mechanism 12. The moving mechanism 16 is, for example, provided with a pair of Y-axis guide rails 18 fixed to the base 4 and generally parallel to the Y-axis. A Y-axis moving table 20 is attached to the Y-axis guide rails 18 in a slidable manner.

A nut portion (not shown) is provided on the underside of the Y-axis moving table 20. A Y-axis ball screw 22, which is generally parallel to the Y-axis guide rail 18, is rotatably connected to this nut portion. A Y-axis pulse motor 24 is connected to the end of the Y-axis ball screw 22. When the Y-axis pulse motor 24 rotates the Y-axis ball screw 22, the Y-axis moving table 20 moves along the Y-axis guide rail 18 in a direction parallel to the Y-axis.

A pair of X-axis guide rails 26, which are generally parallel to the X-axis, are fixed to the upper surface of the Y-axis moving table 20. The X-axis moving table 28 is attached to the X-axis guide rails 26 in a manner that allows it to slide. A nut portion (not shown) is provided on the underside of the X-axis moving table 28.

The X-axis ball screw 30, which is generally parallel to the X-axis guide rail 26, is connected to this nut portion in a rotatable manner. An X-axis pulse motor (not shown) is connected to the end of the X-axis ball screw 30. When the X-axis pulse motor rotates the X-axis ball screw 30, the X-axis moving table 28 moves along the X-axis guide rail 26 in a direction parallel to the X-axis.

A columnar θ table 32 is disposed on the upper surface side of the X-axis moving table 28. The θ table 32 is connected to a rotation drive source (not shown) such as a motor so that it can rotate around an axis of rotation roughly parallel to the Z axis. A disk-shaped chuck table 34 is fixed to the upper surface of the θ table 32.

The chuck table 34 includes, for example, a disk-shaped frame with a recess on the upper surface side, and a porous holding plate fixed to the recess of the frame. The upper surface (holding surface) 34a of the chuck table 34, including the upper surface of the holding plate, is formed so as to be roughly parallel to the X-axis and Y-axis when the chuck table 34 is fixed to the θ table 32, and holds the second surface 11b side of the workpiece 11 via, for example, the tape 13.

The lower side of the holding plate is connected to a suction source (not shown) such as an ejector via a flow path (not shown) provided inside the frame and a valve (not shown) located outside the frame. Therefore, when the tape 13 is brought into contact with the upper surface 34a of the chuck table 34, the valve is opened, and negative pressure from the suction source is applied, the workpiece 11 is sucked into the chuck table 34 via the tape 13. Four clamps 36 are arranged around the periphery of the chuck table 34, which can secure the annular frame 15 that supports the workpiece 11 from all four sides.

The support structure 6 is provided with a support arm 6a that protrudes from its front surface. A processing head 40 that constitutes the laser processing unit 38 is disposed at the tip of the support arm 6a. This processing head 40 includes optical components such as mirrors and lenses, and directs a pulsed laser beam generated by a laser oscillator (not shown) downward.

As a laser oscillator, for example, one that can generate a laser beam with a wavelength that is absorbed by the workpiece 11 (absorbable laser beam) is used. By irradiating the workpiece 11 with a laser beam with such a wavelength, it becomes possible to perform laser ablation, in which the irradiated area irradiated with the laser beam is partially melted and evaporated. However, the wavelength of the laser beam generated by the laser oscillator is not necessarily limited to this.

A camera 42 is disposed in a region to the side of the processing head 40. The camera 42 includes a two-dimensional image sensor, such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor, that is sensitive to light in the visible range, and an imaging lens, and captures an image of the first surface 11a of the workpiece 11 held by the chuck table 34 to generate an image of the workpiece 11.

In the area behind the alignment mechanism 12, a protective film forming device (cleaning device) 46 is disposed, which is used, for example, when forming a protective film containing a resin on the workpiece 11. FIG. 2 is a perspective view of the protective film forming device 46, and FIG. 3 is a cross-sectional view of the protective film forming device 46. Note that, for the sake of convenience, some elements of the protective film forming device 46 are omitted in FIGS. 2 and 3.

As shown in Figures 2 and 3, the protective film forming device 46 is equipped with a holding table (spinner table) 48 that can hold the workpiece 11 together with the frame 15. The holding table 48 includes a disk-shaped frame 50 made of, for example, ceramics or metal. As shown in Figure 3, a recess 50a with a circular opening at the top end is formed on the upper surface side of the frame 50. A disk-shaped holding plate 52 that matches the shape of the recess 50a is fixed to the recess 50a of the frame 50.

The holding plate 52 is made of a porous material such as ceramics, and its upper surface (holding surface) 52a holds the second surface 11b of the workpiece 11 via the tape 13. The upper surface 52a of the holding plate 52 is configured to be generally parallel to the X-axis and Y-axis when the holding plate 52 is fixed to the recess 50a.

Inside the frame 50, a flow path 50b is provided, one end of which opens at the bottom of the recess 50a. Meanwhile, the other end of the flow path 50b is connected to a suction source (not shown) such as an ejector via a valve (not shown). Therefore, when the valve is opened, the negative pressure generated by the suction source acts on the upper surface 52a of the holding plate 52 through the flow path 50b and the recess 50a.

For example, when the workpiece 11 is placed on the holding table 48 and the tape 13 attached to the second surface 11b is in contact with the upper surface 52a of the holding plate 52, and negative pressure from a suction source is applied to this upper surface 52a, the tape 13 is sucked by the upper surface 52a of the holding plate 52. In other words, the workpiece 11 with the tape 13 attached thereto is held by the holding table 48 with the first surface 11a side exposed upward.

As shown in FIG. 2, a rotary drive source 56 such as a motor is connected to the bottom of the frame 50 of the holding table 48 via a cylindrical spindle 54. Therefore, the power generated by this rotary drive source 56 causes the holding table 48 to rotate around the axis (rotation axis) of the spindle 54, which is roughly parallel to the Z axis. A plurality of air actuators 58 (three sets in this embodiment) are provided around the rotary drive source 56. When each air actuator 58 is operated, the holding table 48 rises and falls together with the rotary drive source 56, the spindle 54, etc.

Four sets of holding mechanisms 60 are arranged at approximately equal intervals around the periphery of the frame 50 of the holding table 48, and can hold down the frame 15 placed on the holding table 48 from above by using the centrifugal force generated when the holding table 48 is rotated. As shown in FIG. 3, each holding mechanism 60 has a support arm 62 that protrudes outward from the periphery of the frame 50.

The base end (inner end) of the support arm 62 is fixed to the periphery of the frame 50 with a screw or the like (not shown). The tip end (outer end) of the support arm 62 is provided with a support shaft 64 that is, for example, generally parallel to the upper surface 52a of the holding plate 52 and generally perpendicular to a straight line connecting the center of the holding plate 52 and the tip end of the support arm 62 (i.e., the direction along the radius of the holding plate 52, the radial direction r in FIG. 3). A pressing member 66 is supported on the support shaft 64 in a freely rotatable manner.

The pressing member 66 includes a support portion 66a supported by the support shaft 64, a hook-shaped pressing portion 66b located on one side of the support portion 66a, and a weight portion 66c located on the other side of the support portion 66a. The weight of the weight portion 66c is, for example, greater than the weight of the pressing portion 66b, and when the holding table 48 is not rotating at high speed (when no large centrifugal force is acting on the pressing member 66), the tip of the pressing portion 66b is positioned at an upper retracted position.

When the holding table 48 is rotated at high speed with the frame 15 placed on it, a large centrifugal force accompanying this rotation is applied to the holding member 66. As described above, the weight of the weight portion 66c is greater than the weight of the holding member 66b, so when the holding table 48 is rotated at high speed, the large centrifugal force accompanying this rotation causes the holding member 66 to rotate around the support shaft 64 so that the weight portion 66c moves outward.

As a result, the tip of the pressing portion 66b comes into contact with the frame 15 placed on the holding table 48 from above, and the frame 15 is pressed downward by the pressing member 66. Therefore, even when the holding table 48 is rotated at high speed, the frame 15 is properly held by this pressing mechanism 60.

As shown in FIG. 2, a nozzle (resin supply nozzle, cleaning nozzle) 70 constituting a fluid supply unit (protective film forming unit, cleaning unit) 68 is disposed next to the holding table 48. This nozzle 70 is connected to a liquid resin supply source (not shown) that supplies liquid resin, which is the raw material for the protective film, and to a rotation drive source (not shown) such as a motor. Therefore, the nozzle 70 moves above the holding table 48 by the power of the rotation drive source, and can supply liquid resin to the first surface 11a of the workpiece 11 held on the holding table 48.

The nozzle 70 is also connected to a cleaning fluid supply source (not shown) that supplies cleaning fluid. Therefore, the nozzle 70 can spray cleaning fluid toward the first surface 11a of the workpiece 11 held on the holding table 48, the upper surface 52a of the holding table 48 (holding plate 52), etc., while oscillating above the holding table 48 by the power of the rotary drive source.

In this way, the fluid supply unit 68 in this embodiment can apply liquid resin to the first surface 11a of the workpiece 11 to form a protective film, and can also clean the first surface 11a of the workpiece 11 and the upper surface 52a of the holding table 48, etc.

The liquid resin used is, for example, a water-soluble resin that can be easily washed away with water, such as HogoMax (registered trademark) made by Disco Corporation. It is also preferable that a fluorescent material or a phosphorescent material is added to this liquid resin. The cleaning fluid used may be, for example, a liquid such as pure water, or a mixed fluid (two-fluid) in which a gas such as air is mixed with a liquid.

As shown in FIG. 2, the holding table 48 and the fluid supply unit 68 are housed in the space inside the liquid receiving container 72. This liquid receiving container 72 includes a disk-shaped bottom wall 72a and a cylindrical outer wall 72b provided along the outer periphery of the bottom wall 72a. In other words, the liquid receiving container 72 is formed in a bottomed cylindrical shape with a circular opening 72c at the upper end.

A circular opening through which the spindle 54 passes is formed in the center of the disk-shaped bottom wall 72a, and a cylindrical inner wall 72d having a smaller diameter and height than the outer wall 72b is provided to surround this opening. Therefore, for example, even if the liquid in the fluid sprayed from the nozzle 70 collides with the workpiece 11 or the holding table 48 and splashes around, it will accumulate in the area on the bottom wall 72a between the cylindrical outer wall 72b and the cylindrical inner wall 72d. In addition, a cylindrical cover 74 that surrounds the spindle 54 is provided at the bottom of the holding table 48.

A drain port 72e penetrating the bottom wall 72a in the thickness direction is provided in the portion of the bottom wall 72a between the outer peripheral wall 72b and the inner peripheral wall 72d. A drain hose 76 is connected to the drain port 72e, and liquid accumulated in the liquid receiving container 72 is discharged to the outside of the protective film forming device 46 through the drain port 72e and the drain hose 76. In addition, legs 78 are provided at the bottom of the liquid receiving container 72, and the height of the liquid receiving container 72 is adjusted to match the height of the holding table 48, etc.

As shown in FIG. 3, a light source 80 capable of emitting light toward the upper surface 52a is disposed in the region above the holding table 48 (upper surface 52a). This light source 80 typically includes an ultraviolet LED (Light Emitting Diode), and emits downward light (ultraviolet rays) with a wavelength that is absorbed by a protective film formed on the workpiece 11 using liquid resin as a raw material. Note that the type of light source 80 and the wavelength of light emitted from the light source 80 are not necessarily limited to these.

An imaging unit 82 capable of receiving light from the upper surface 52a side and forming an image is disposed next to the light source 80. This imaging unit 82 includes, for example, a light receiving element 84 that is sensitive to the wavelength of light (fluorescence, phosphorescence, etc.) emitted by the protective film that absorbs the light emitted from the light source 80. The light receiving element 84 is typically an optical sensor such as a photodiode (PD). Of course, a one-dimensional image sensor, a two-dimensional image sensor, etc. may also be used as the light receiving element 84.

The light source 80 and the imaging unit 82 are supported, for example, by a ball-screw type linear motion mechanism 86 arranged above the holding table 48, and can move along the radial direction of the holding table 48 (radial direction r in FIG. 3). By controlling the movement of the light source 80 and the imaging unit 82 by this linear motion mechanism 86 and the rotation of the holding table 48, the light source 80 and the imaging unit 82 can be positioned above any position on the holding table 48.

Therefore, for example, by rotating the holding table 48 and moving the light source 80 and the imaging unit 82 along the radial direction (radial direction r) of the holding table 48 while detecting the light emitted from the upper surface 52a side with the light receiving element 84 of the imaging unit 82, the intensity distribution of the light emitted from the upper surface 52a side can be obtained. In other words, the imaging unit 82 can image the upper surface 52a from above the upper surface 52a to form an image (light intensity distribution).

As shown in FIG. 1, the alignment mechanism 12, the transport mechanism 14, the moving mechanism 16, the laser processing unit 38, the camera 42, the protective film forming device 46, and other elements are connected to a controller 88. The controller 88 is typically configured as a computer including a processing device 90 and a storage device 92, and controls the operation of each element of the laser processing device 2, including the protective film forming device 46, so that the workpiece 11 is appropriately processed.

The processing device 90 is typically a CPU (Central Processing Unit) and performs various processes necessary to control the above-mentioned elements. The storage device 92 includes, for example, a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a hard disk drive or flash memory. The functions of this controller 88 are realized, for example, by the processing device 90 operating in accordance with software such as a program stored in the storage device 92.

Figure 4 is a flowchart of the determination method used by the protective film forming device 46 described above, and the protective film forming method including this determination method. For example, the workpiece 11 that is pulled from the cassette 10 to the guide rails 12a and 12b of the alignment mechanism 12 by the transport mechanism 14 has a protective film formed on its first surface 11a by the protective film forming device 46 before being processed by the laser beam.

Figure 5 is a cross-sectional view showing the exposed top surface 52a of the holding table 48 of the protective film forming device 46. As shown in Figure 5, resin pieces 21 containing the same resin as the protective film may adhere to the top surface 52a of the holding table 48 for various reasons. Therefore, in the determination method and protective film forming method of this embodiment, it is determined whether or not resin pieces 21 are adhered to the top surface 52a of the holding table 48 before the workpiece 11 is held by the holding table 48.

Each step of the determination method and protective film forming method is performed by the controller 88 in accordance with software such as a program. First, when the upper surface 52a of the holding table 48 is not holding the workpiece 11, light is emitted from the light source 80 disposed above the upper surface 52a toward the upper surface 52a (step ST1). Figure 6 is a cross-sectional view showing the light 23 being emitted from the light source 80 toward the upper surface 52a of the holding table 48.

Specifically, the controller 88 causes the light source 80 to emit light 23 with a wavelength that is absorbed by the protective film made from the liquid resin described above. At this time, the controller 88 causes the rotation drive source 56 to rotate the holding table 48 while moving the light source 80 and the imaging unit 82 with the linear motion mechanism 86. In other words, the light source 80 irradiates the upper surface 52a of the holding table 48 with light 23 while moving together with the imaging unit 82 relative to the upper surface 52a in a vortex motion.

The number of rotations (rotational speed) of the holding table 48 is, for example, 100 rpm to 1000 rpm, typically 500 rpm, and the movement speed of the light source 80 and the imaging unit 82 is, for example, 1.0 mm/s to 10 mm/s, typically 5.3 mm/s. However, the number of rotations of the holding table 48 and the movement speed of the light source 80 and the imaging unit 82 are not limited to these values.

When the light 23 as described above is emitted from the light source 80, the light emitted upward from the upper surface 52a side is detected by the light receiving element 84 of the imaging unit 82. FIG. 7 is a cross-sectional view showing how the light 25 emitted from the resin piece 21 attached to the upper surface 52a of the holding table 48 is detected by the imaging unit 82. As described above, the light receiving element 84 is configured to be sensitive to the wavelength of light (fluorescence, phosphorescence, etc.) emitted by the protective film (including the resin piece 21 containing the same resin as the protective film) that has absorbed the light 23 emitted from the light source 80.

As described above, the imaging unit 82 moves relative to the upper surface 52a of the holding table 48 together with the light source 80 in a vortex pattern. Therefore, the imaging unit 82 obtains a two-dimensional intensity distribution (i.e., an image) of the light emitted upward from the upper surface 52a. In other words, the imaging unit 82 captures an image of the upper surface 52a of the holding table 48.

In this embodiment, the angle of incidence of light 23 with respect to upper surface 52a is adjusted so that light 23 reflected by upper surface 52a is less likely to enter light receiving element 84. More preferably, light receiving element 84 is configured to have higher sensitivity to the wavelength of light emitted by the protective film that absorbs light 23 than the wavelength of light 23 emitted from light source 80 and reflected by upper surface 52a. Therefore, this imaging unit 82 can obtain a two-dimensional intensity distribution (i.e., an image) of light 25 emitted from resin piece 21 attached to upper surface 52a.

In this manner, the controller 88 causes the imaging unit 82 to capture an image of the upper surface 52a of the holding table 48 when the workpiece 11 is not being held, while the light source 80 is emitting light 23, and obtains an image of the upper surface 52a of the holding table 48 (step ST2). FIG. 8 is a diagram showing an example of an image 31 of the upper surface 52a of the holding table 48.

As shown in FIG. 8, in the area inside the outline 31a of the holding table 48 in the image 31, there is a high-luminance area 31b where the imaging unit 82 has detected the light 25 emitted from the resin piece 21. The area excluding the high-luminance area 31b is a low-luminance area 31c that is lower in luminance than the high-luminance area 31b. Based on this image 31, the controller 88 determines whether or not the resin piece 21 is attached to the upper surface 52a of the holding table 48 (step ST3).

For example, if a high-luminance area 31b with a luminance higher than a predetermined threshold value is present in an area inside the contour 31a in the image 31, the controller 88 determines that a resin piece 21 is attached to the upper surface 52a of the holding table 48. On the other hand, if a high-luminance area 31b with a luminance higher than this threshold value is not present in an area inside the contour 31a in the image 31, the controller 88 determines that a resin piece 21 is not attached to the upper surface 52a of the holding table 48.

If it is determined that resin pieces 21 are attached to the upper surface 52a of the holding table 48 (YES in step ST3), the upper surface 52a of the holding table 48 is cleaned by the fluid supply unit 68 (step ST4). Figure 9 is a cross-sectional view showing the state in which the upper surface 52a of the holding table 48 has been cleaned and the resin pieces 21 have been removed.

When cleaning the top surface 52a of the holding table 48, as shown in FIG. 9, the controller 88 rotates the holding table 48 and causes the nozzle 70 to spray the cleaning fluid 27 while oscillating the nozzle 70. As a result, the top surface 52a of the holding table 48 is cleaned with the fluid 27, and the resin pieces 21 are removed from the top surface 52a of the holding table 48.

After the upper surface 52a of the holding table 48 has been cleaned, or if it is determined that no resin pieces 21 are attached to the upper surface 52a of the holding table 48 (NO in step ST3), a protective film is formed on the first surface 11a side of the workpiece 11. Figure 10 is a cross-sectional view showing how the protective film is formed on the workpiece 11.

Specifically, first, the controller 88 causes the transport mechanism 14 to place the workpiece 11, which is supported on the frame 15 via the tape 13, on the upper surface 52a of the holding table 48 so that the first surface 11a side is exposed upward. That is, the controller 88 causes the transport mechanism 14 to bring the tape 13 attached to the second surface 11b side of the workpiece 11 into contact with the upper surface 52a of the holding table 48.

Next, the controller 88 opens the valve and applies the negative pressure generated by the suction source to the upper surface 52a of the holding plate 52. As a result, the tape 13 attached to the second surface 11b of the workpiece 11 is sucked to the upper surface 52a of the holding table 48. In other words, the workpiece 11 with the tape 13 attached to the second surface 11b is held on the holding table 48 with the first surface 11a exposed upward (step ST5).

Then, as shown in FIG. 10, the controller 88 moves the nozzle 70 above the workpiece 11 and drips liquid resin 29 onto the nozzle 70, and then rotates the holding table 48 at high speed using the rotary drive source 56. As a result, the liquid resin 29, which is the raw material for the protective film, is applied to the first surface 11a of the workpiece 11 (step ST6). The liquid resin 29 applied to the first surface 11a of the workpiece 11 is dried to complete the protective film covering the first surface 11a.

As described above, the protective film forming device 46 of this embodiment emits light from the light source 80 above the upper surface 52a toward the upper surface 52a when the upper surface (holding surface) 52a of the holding table 48 is not holding the workpiece 11, then causes the imaging unit 82 to capture an image of the upper surface 52a when the workpiece 11 is not being held, thereby obtaining an image 31 of the upper surface 52a, and then determines whether or not a resin piece 21 is attached to the upper surface 52a based on the image 31, thereby making it possible to appropriately determine whether or not a resin piece 21 is attached to the upper surface 52a of the holding table 48.

The present invention is not limited to the above-described embodiment, and can be modified in various ways. For example, the protective film forming device 46 in the above-described embodiment includes a fluid supply unit 68 that combines the functions of both a protective film forming unit and a cleaning unit, but the protective film forming device of the present invention may include a protective film forming unit and a cleaning unit separate from the protective film forming unit. In this case, the protective film forming unit has a resin supply nozzle, and the cleaning unit has a cleaning nozzle.

In addition, in the above-described embodiment, a controller 88 for controlling the operation of the laser processing device 2 is used to control the operation of the protective film forming device 46 including the light source 80 and the imaging unit 82, but the protective film forming device 46 may be provided with a controller independent of the laser processing device 2.

In addition, in the above-described embodiment, the presence or absence of the resin piece 21 adhering to the upper surface 52a of the holding table 48 is determined using light such as fluorescence and phosphorescence emitted by the protective film (resin piece 21), but the presence or absence of the resin piece 21 adhering to the upper surface 52a of the holding table 48 may be determined based on other principles. For example, the presence or absence of the resin piece 21 adhering to the upper surface 52a of the holding table 48 can be determined using the difference in optical properties (reflectance, absorbance, etc.) between the upper surface 52a of the holding table 48 and the resin piece 21.

In addition, the structures, methods, etc. of the above-mentioned embodiments and modified examples can be modified as appropriate without departing from the scope of the purpose of the present invention.

2: Laser processing device 4: Base 4a: Storage section 6: Support structure 6a: Support arm 8: Cassette support base 10: Cassette 12: Alignment mechanism 12a: Guide rail 12b: Guide rail 14: Conveyance mechanism 16: Movement mechanism (processing feed mechanism, indexing feed mechanism)
18: Y-axis guide rail 20: Y-axis moving table 22: Y-axis ball screw 24: Y-axis pulse motor 26: X-axis guide rail 28: X-axis moving table 30: X-axis ball screw 32: θ table 34: Chuck table 34a: Upper surface (holding surface)
36: Clamp 38: Laser processing unit 40: Processing head 42: Camera 46: Protective film forming device (cleaning device)
48: Holding table (spinner table)
50: Frame 50a: Recess 50b: Channel 52: Holding plate 52a: Top surface (holding surface)
54: Spindle 56: Rotation drive source 58: Air actuator 60: Pressing mechanism 62: Support arm 64: Support shaft 66: Pressing member 66a: Support portion 66b: Pressing portion 66c: Weight portion 68: Fluid supply unit (protective film forming unit, cleaning unit)
70: Nozzle (resin supply nozzle, cleaning nozzle)
72: Liquid receiving container 72a: Bottom wall 72b: Outer peripheral wall 72c: Opening 72d: Inner peripheral wall 72e: Drain port 74: Cover 76: Drain hose 78: Leg 80: Light source 82: Imaging unit 84: Light receiving element 86: Linear motion mechanism 88: Controller 90: Processing device 92: Storage device 11: Workpiece 11a: First surface 11b: Second surface 13: Tape (dicing tape)
15: Frame 21: Resin piece 23: Light 25: Light 27: Fluid 29: Resin 31: Image 31a: Contour 31b: High brightness area 31c: Low brightness area

Claims (7)

A protective film forming apparatus for forming a protective film including a resin on a first surface of a workpiece having a first surface and a second surface opposite to the first surface,
a holding table having a holding surface for holding the second surface of the workpiece and connected to a rotary drive source;
a protective film forming unit having a resin supply nozzle for supplying a liquid resin that is a raw material of the protective film, and applying the liquid resin to the first surface of the workpiece held by the holding surface of the holding table to form the protective film;
a light source that emits light from above the holding surface of the holding table toward the holding surface;
an imaging unit having a light receiving element and configured to image the holding surface side of the holding table from above the holding surface of the holding table to form an image;
a cleaning unit having a cleaning nozzle for supplying a cleaning fluid and cleaning the holding surface of the holding table;
a controller having a processing device and a storage device, the processing device operating in accordance with a program stored in the storage device to control operations of the light source and the imaging unit;
Including,
The controller, according to the program,
causing the light source to emit the light while the holding surface of the holding table is not holding the workpiece;
While the light source is emitting the light, the holding surface is imaged by the imaging unit in a state where the workpiece is not being held, thereby obtaining an image of the holding surface;
The protective film forming apparatus determines whether or not resin pieces containing the resin are attached to the holding surface based on the image. the light source emits light at a wavelength that is absorbed by the protective film;
2. The protective film forming apparatus according to claim 1, wherein the light receiving element of the imaging unit has sensitivity to a wavelength of light emitted by the protective film after absorbing the light. If it is determined that the resin piece is attached to the holding surface,
3. The protective film forming apparatus according to claim 1, wherein the controller causes the cleaning unit to clean the support surface in accordance with the program. A method for determining whether or not a resin piece, which contains a resin contained in a protective film of a workpiece, is attached to a holding surface of a holding table having a holding surface for holding the workpiece, the method comprising:
emitting light from a light source above the holding surface toward the holding surface while the holding surface of the holding table is not holding the workpiece;
With the light source emitting the light, an image of the holding surface in a state where the workpiece is not being held is captured by an imaging unit to obtain an image of the holding surface;
A method for determining whether or not the resin pieces are attached to the holding surface based on the image. the light source emits light at a wavelength that is absorbed by the protective film;
5. The method according to claim 4, wherein the imaging unit has a light receiving element having sensitivity to the wavelength of light emitted by the protective film that has absorbed the light. If it is determined that the resin piece is attached to the holding surface,
The method according to claim 4 or 5, further comprising cleaning the holding surface with a cleaning unit. A protective film forming method including the determination method according to claim 6,
when it is determined that the resin pieces are attached to the holding surface and after the holding surface is cleaned by the cleaning unit, or when it is determined that the resin pieces are not attached to the holding surface, the second surface of the workpiece, which has a first surface and a second surface opposite to the first surface, is held by the holding surface of the holding table;
A protective film forming method for forming a protective film by applying a liquid resin, which is a raw material of the protective film, to the first surface of the workpiece held by the holding surface of the holding table.

Images