JP7614710B2 - Protective film removal method and coating/cleaning device - Google Patents

Description

The present invention relates to a method for removing a protective film that has adhered to the surface of a ring frame, and a coating and cleaning device that cleans the protective film that has adhered to the surface of a ring frame.

In the manufacturing process of semiconductor device chips, a wafer (workpiece) has a number of planned division lines (streets) set on its surface, and devices are formed in each of the areas defined by the streets. The wafer is then processed along each of the streets.

When processing a workpiece along each street, for example, a laser beam having a wavelength that is absorbed by the workpiece is used to perform ablation processing on the workpiece (see, for example, Patent Document 1). However, when ablation processing is performed, debris adheres to the surface side of the workpiece, contaminating the surface side.

In order to prevent contamination by debris, a processing method has been developed in which the surface side of the workpiece is covered with a protective film made of a water-soluble resin before ablation processing, and the protective film and debris are washed and removed with cleaning water after ablation processing (see, for example, Patent Document 2).

To cover the front side of the workpiece with a protective film, first place the workpiece in the opening of a metal ring frame, and then attach a circular protective tape to the back side of the ring frame and the back side of the workpiece, forming a workpiece unit in which the workpiece is supported by the ring frame via the protective tape.

Next, while the back side of the workpiece is held by suction on the spinner table and the spinner table is rotating, water-soluble resin is supplied to the front side of the workpiece from above the spinner table, and then the water-soluble resin is dried. This causes the front side of the workpiece to be coated with a protective film.

However, due to the centrifugal force generated by the rotation of the spinner table, the liquid resin may fly outward beyond the outer edge of the workpiece and adhere to the surface of the ring frame. In this case, a protective film is also formed on the surface of the ring frame.

When the workpiece unit is transported, the surface of the ring frame comes into contact with the suction mechanism of the transport device, so if a protective film is formed on the surface of the ring frame, the protective film also adheres to the suction mechanism. The transport device is provided in, for example, a laser processing device, and when the transport device moves, the attached protective film moves with it, causing contamination of the inside of the laser processing device.

In order to prevent contamination by the protective film, a protective film forming device has been proposed that uses a cleaning nozzle and an air nozzle to clean and dry the ring frame after the protective film is formed (see, for example, Patent Document 3). However, even when using this protective film forming device, it is not possible to confirm whether the protective film attached to the surface of the ring frame has been sufficiently removed.

To address this issue, it may be possible to set the cleaning time to be longer than the expected cleaning time in order to thoroughly remove the protective film, but this would result in the problem of it taking longer to clean the ring frame.

Japanese Patent Application Publication No. 10-305420 JP 2006-140311 A JP 2014-175461 A

The present invention was made in consideration of these problems, and aims to limit the cleaning time of the ring frame and to confirm whether the protective film adhering to the surface of the ring frame has been sufficiently removed.

According to one aspect of the present invention, there is provided a protective film removal method for removing a protective film adhering to a surface of a ring frame in a workpiece unit having a ring frame, a tape attached to a back surface of the ring frame, and a workpiece supported by the ring frame via the tape, the method comprising: a holding step of holding the workpiece unit on a holding table; a supply step of supplying liquid resin to the surface of the workpiece held by the holding table while rotating the holding table after the holding step; a detection step of detecting a thickness of the protective film formed on the surface of the ring frame after the supply step; and a cleaning step of spraying cleaning water onto the surface side of the ring frame, in which in the cleaning step, the cleaning water is sprayed while detecting the thickness of the protective film on the surface of the ring frame to clean the ring frame , and in the cleaning step, the spraying of the cleaning water onto the ring frame is continued as long as the thickness of the protective film on the ring frame exceeds a threshold value within a predetermined time scheduled as a cleaning time in the cleaning step .

According to another aspect of the present invention, there is provided a coating and cleaning device which applies liquid resin to a surface of a workpiece in a workpiece unit having a ring frame, a tape affixed to a back surface of the ring frame, and a workpiece supported by the ring frame via the tape, and cleans a protective film that has adhered to the surface of the ring frame as a result of the application of the liquid resin, the coating and cleaning device comprising: a holding table which holds the workpiece unit; a liquid resin supplying unit which supplies the liquid resin to the surface of the workpiece held by the holding table; a detection unit which detects the thickness of the protective film on the surface of the ring frame; a cleaning water spraying unit which sprays cleaning water onto the surface of the ring frame, and a control unit which controls the operation of the holding table, the liquid resin supply unit, the detection unit, and the cleaning water spraying unit, wherein the control unit controls the operation of the cleaning water spraying unit while detecting the thickness of the protective film on the surface of the ring frame with the detection unit, and the control unit causes the cleaning water spraying unit to continue spraying the cleaning water as long as the thickness of the protective film on the ring frame exceeds a threshold value while detecting the thickness of the protective film with the detection unit within a predetermined time scheduled as a cleaning time.

The protective film removal method according to one aspect of the present invention includes a detection step of detecting the thickness of the protective film formed by adhering to the surface of the ring frame, and a cleaning step of spraying cleaning water onto the surface of the ring frame while detecting the thickness of the protective film. In the cleaning step, cleaning water is sprayed while detecting the thickness of the protective film on the surface of the ring frame, and the ring frame is cleaned, so that the ring frame can be cleaned while checking whether the protective film adhering to the ring frame has been sufficiently removed.

In addition, since the ring frame is cleaned while detecting the thickness of the protective film on the surface of the ring frame, if the protective film has been sufficiently removed, the cleaning step can be terminated even before the predetermined time scheduled for cleaning has elapsed. Therefore, the cleaning time for the ring frame can be limited.

FIG. FIG. 4 is a partial cross-sectional side view of the detection unit. FIG. 1 is a flow diagram of a protective film removing method. FIG. 2 is a partial cross-sectional side view of the coating and cleaning device. FIG. 13 is a top view illustrating the arrangement of the detection unit and the third nozzle.

An embodiment of one aspect of the present invention will be described with reference to the accompanying drawings. First, the workpiece 11 will be described with reference to FIG. 1. The workpiece 11 in this embodiment includes a disk-shaped wafer made of silicon (Si).

However, there are no limitations on the material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may include a wafer formed of a semiconductor material other than silicon, such as gallium nitride (GaN), gallium arsenide (GaAs), silicon carbide (SiC), etc.

On the surface 11a side of the workpiece 11, multiple mutually orthogonal planned division lines (streets) are set. In each area partitioned by the multiple streets, a device such as an IC (Integrated Circuit) is formed.

A protective tape (tape) 13 having a larger diameter than the workpiece 11 is attached to the back surface 11b of the workpiece 11. In addition, the back surface 15b of a ring frame 15 made of metal is attached to the outer periphery of the protective tape 13.

For example, the workpiece 11 is placed in the opening 15c of the ring frame 15 with the surface 11a of the workpiece 11 and the surface 15a of the ring frame 15 facing downward. Then, with the back surface 11b of the workpiece 11 and the back surface 15b of the ring frame 15 exposed upward, protective tape 13 is applied to the back surfaces 11b and 15b.

This forms a workpiece unit 17 in which the workpiece 11, protective tape 13, and ring frame 15 are integrated. In the workpiece unit 17, the workpiece 11 is supported by the ring frame 15 via the protective tape 13.

In this embodiment, the workpiece 11 is processed along each street with a laser beam. Specifically, a laser beam having a wavelength (e.g., a central wavelength of 355 nm) that is absorbed by the workpiece 11 is used to perform ablation processing on the workpiece 11 along each street.

Before the ablation process, in order to prevent debris generated during the ablation process from adhering to the surface 11a, the surface 11a side is covered with a protective film 19 (see Figure 4) made of a water-soluble resin and having a thickness of about 0.5 μm to 1.5 μm.

A coating and cleaning apparatus 2 is used to form the protective film 19. FIG. 1 is a perspective view of the coating and cleaning apparatus 2. The X-axis direction, Y-axis direction, and Z-axis direction shown in FIG. 1 are mutually orthogonal. The Z-axis direction is, for example, parallel to the vertical direction, and the X-Y plane is, for example, parallel to the horizontal plane.

The coating and cleaning device 2 is mounted on a laser processing device and is used to form and remove a protective film 19. The coating and cleaning device 2 includes a cylindrical chamber 4. Note that FIG. 1 shows a cutaway view of the chamber 4. A disk-shaped spinner table (holding table) 6 is disposed within the chamber 4.

The spinner table 6 has a disk-shaped frame 8 made of metal. A disk-shaped recess is formed on the upper surface of the frame 8, and a disk-shaped porous plate 10 made of porous ceramics is fixed in this recess.

The upper surface of the frame 8 and the upper surface of the porous plate 10 are substantially flush with each other, forming a substantially flat holding surface 6a. A predetermined flow path is formed in the frame 8. One end of this flow path is connected to a suction source (not shown) such as an ejector, and the other end of the flow path is exposed to the recess.

When the suction source is operated, negative pressure is transmitted to the upper surface of the porous plate 10, and the workpiece 11 is suction-held on the holding surface 6a via the protective tape 13. A suction port (not shown) for suction-holding the back surface 15b of the ring frame 15 may be provided on the upper surface of the frame 8. A table base (not shown) is provided below the spinner table 6.

A rotary drive source (not shown), such as a motor, is provided under the table base. The rotary drive source's rotating shaft 12 is connected to the spinner table 6 via the table base. When the rotary drive source is operated, the spinner table 6 rotates around the rotating shaft 12 at a predetermined rotational speed.

The rotary drive source is supported by a lifting mechanism (not shown) having an air cylinder or the like. The lifting mechanism raises the spinner table 6 when the workpiece unit 17 is loaded and unloaded, and lowers the spinner table 6 when the protective film 19 is formed and cleaned.

A rotating shaft 14 is provided outside the spinner table 6 and inside the inner wall of the chamber 4, and is arranged approximately parallel to the Z-axis direction. The base end of a first arm 16 is fixed to the upper end of the rotating shaft 14. The rotating shaft 14 can swing the first arm 16 around the rotating shaft 14 within a predetermined angular range.

A first nozzle 18 is fixed to the tip of the first arm 16 so as to face downward. A liquid resin supply source 20 is connected to the first nozzle 18 via a predetermined flow path. The liquid resin supply source 20 has a tank (not shown) in which liquid resin 21 is stored.

A first pump and a first solenoid valve (neither shown) are provided in a predetermined flow path between the tank of the liquid resin supply source 20 and the first nozzle 18. The first nozzle 18, the liquid resin supply source 20, the first solenoid valve, etc. constitute a liquid resin supply unit 22 that supplies liquid resin 21 to the surface 11a side.

The liquid resin 21 contains, for example, a water-soluble resin such as polyvinyl alcohol or polyethylene glycol, a light absorbent such as ferulic acid or dihydroxybenzophenone, and an additive. The liquid resin supply unit 22 supplies the liquid resin 21 to the surface 11a of the workpiece 11 held by suction on the holding surface 6a.

By rotating the spinner table 6 at a predetermined speed, the supplied liquid resin 21 spreads due to centrifugal force and is applied to the entire surface 11a. Thereafter, the supply of the liquid resin 21 is stopped and the liquid resin 21 is dried, and the surface 11a is covered with the protective film 19.

By the way, the liquid resin 21 adheres to the surface 15a of the ring frame 15 due to centrifugal force, and a protective film 19 is also formed on the surface 15a. When the protective film 19 is irradiated with excitation light α having a central wavelength (for example, a central wavelength of 365 nm), the light absorbent in the protective film 19 emits fluorescence β in a wavelength band of about 420 nm to 430 nm (see Figure 2).

The light absorbing agent is dispersed almost uniformly in the protective film 19 at a predetermined density, so the intensity of the fluorescence β obtained when the protective film 19 is irradiated with excitation light α of a predetermined intensity corresponds to the thickness of the protective film 19 (for example, is approximately proportional). Therefore, the intensity of the fluorescence β can be used to detect the thickness of the protective film 19 on the surface 15a.

Returning to FIG. 1, a second arm 24 is disposed below the first arm 16. The base end of the second arm 24 is also fixed to the upper end of the rotating shaft 14. A second nozzle 26 is fixed to the tip of the second arm 24 so as to face downward.

The second nozzle 26 is connected to a cleaning water supply source 28 via a predetermined flow path. The cleaning water supply source 28 has a tank (not shown) in which cleaning water 23 such as pure water is stored. A second pump and a second solenoid valve (neither shown) are provided in the predetermined flow path between the tank and the second nozzle 26.

The second nozzle 26, the cleaning water supply source 28, the second solenoid valve, etc., constitute the workpiece cleaning unit 30. The workpiece cleaning unit 30 is, for example, a high-pressure cleaning unit, and sprays cleaning water 23 pressurized to a predetermined value of 5 MPa to 10 MPa downward from the second nozzle 26.

The workpiece cleaning unit 30 may be a two-fluid cleaning unit that sprays a mixture of pure water and air downward from the second nozzle 26. The workpiece cleaning unit 30 may further include an air nozzle (not shown) that sprays dry air.

Outside the spinner table 6 and inside the inner wall of the chamber 4, at a position different from the rotation shaft 14, another rotation shaft 32 is provided that is arranged approximately parallel to the Z-axis direction. The base end of a third arm 34 is fixed to the upper end of the rotation shaft 32.

The tip of the third arm 34 is folded back toward the base end of the third arm 34 and faces diagonally downward. A third nozzle 36 is fixed to this tip. A cleaning water supply source 28 is connected to the third nozzle 36 via a specified flow path.

The third nozzle 36 is supplied with cleaning water 23 from the cleaning water supply source 28 via a third solenoid valve (not shown). The third nozzle 36, the cleaning water supply source 28, the third solenoid valve, etc. constitute a cleaning water injection unit 38 for cleaning and removing the protective film 19 adhering to the surface 15a of the ring frame 15.

When the third solenoid valve is open, the cleaning water 23 is sprayed diagonally outward from the third nozzle 36 (i.e., radially outward and downward from the holding surface 6a). In this way, by spraying the cleaning water 23 diagonally outward, the amount of cleaning water 23 that splashes toward the center of the holding surface 6a can be reduced.

The coating and cleaning device 2 is provided with a guide rail 42 that extends approximately parallel to the X-Y plane so as to pass through the center 6b (see FIG. 5) of the holding surface 6a and intersect at right angles with a straight line (not shown) that is approximately parallel to the Z-axis direction. The guide rail 42 is a predetermined distance away from the upper end of the chamber 4 so as not to interfere with a transport device (not shown) that transports the workpiece unit 17.

An actuator 44 is provided on the underside of the guide rail 42 so as to be movable along the extension direction of the guide rail 42. The actuator 44 has a rod 44a that is extendable in the Z-axis direction.

A cylindrical detection unit 46 is provided at the lower end of the rod 44a to detect the thickness of the protective film 19 formed on the surface 15a of the ring frame 15. A semi-cylindrical cover 46a made of stainless steel is provided on the outer peripheral side of the detection unit 46 to prevent contamination by the cleaning water 23, etc.

The configuration of the detection unit 46 will now be described with reference to FIG. 2. FIG. 2 is a partially cross-sectional side view of the detection unit 46. Note that the cover 46a is omitted in FIG. 2. The detection unit 46 has a photomultiplier tube 50.

The photomultiplier tube 50 has a cylindrical glass bulb 52 with a vacuum-state internal space. The photomultiplier tube 50 of this embodiment is a so-called side-on type, and the bulb 52 is arranged so that the height direction of the cylinder is perpendicular to the Z-axis direction.

A photocathode 54 is disposed inside the bulb 52. The photocathode 54 receives light incident on the side of the bulb 52 and emits electrons. The number of emitted electrons is amplified in an avalanche manner by multiple dynodes (not shown).

The number of secondary electrons amplified by the photomultiplier tube 50 finally reaches an anode (not shown) and is detected as a current signal. For example, the number of secondary electrons is counted by measuring the current signal with an oscilloscope.

By counting the number of secondary electrons, the intensity of the light (i.e., the above-mentioned fluorescence β) incident on the photocathode 54 can be detected. The number of secondary electrons may also be counted digitally using a specified circuit.

The photomultiplier tube 50 is inserted into the internal space 56a of the cylindrical fixed part 56 through an opening on the side of the fixed part 56, and is positioned so that the photocathode 54 faces downward. A truncated cone-shaped opening 56b whose diameter increases toward the bottom is formed at the bottom of the fixed part 56, and the photocathode 54 is located directly above the opening 56b.

A circular connecting part 58 is fixed to the lower part of the fixed part 56. A truncated cone-shaped opening 58a is formed in the connecting part 58, the diameter of which increases toward the bottom. The opening 58a is arranged concentrically with the opening 56b.

A fluorescence transmission filter 60 is provided at the top of the opening 58a, which transmits the fluorescence β but does not transmit light of wavelength bands other than the fluorescence β. A cylindrical reflector fixing part 62 is fixed to the bottom of the connecting part 58.

A ring-shaped recess 62a is formed in the upper part of the side of the reflector fixing part 62. A female thread is formed in the bottom surface of the recess 62a, and a male thread formed on the outer peripheral side surface 64a of the ring-shaped positioning ring 64 is screwed into this female thread.

A truncated cone-shaped opening 64b is formed in the radial center of the positioning ring 64, the diameter of which increases toward the bottom. Opening 64b is arranged concentrically with openings 56b and 58a.

A cylindrical spacer 66 is disposed below the positioning ring 64. A cylindrical mirror holder 68 is disposed at the bottom of the spacer 66. The mirror holder 68 has multiple (e.g., four) arms 68a that each protrude outward from one side.

The mirror holder 68 is arranged so that each arm 68a contacts the bottom of the spacer 66. Note that two arms 68a are shown in FIG. 2. Inside the mirror holder 68, a recess 68b is formed with its opening facing downward.

A triangular prism-shaped mirror 68c is fixed to the recess 68b. An opening 68d is formed on the side of the recess 68b. One end of a cylindrical light guide tube 70 is fixed to the opening 68d.

A condenser lens 70a is provided at one end of the light guide tube 70. The light guide tube 70 is arranged to pass through through holes provided on the sides of the reflector fixing part 62 and the spacer 66, and the other end of the light guide tube 70 is located outside the reflector fixing part 62.

An excitation light transmission filter 70b is provided at the other end of the light guide tube 70, which transmits the excitation light α but does not transmit light of wavelength bands other than the excitation light α. A light source unit 72 that emits the excitation light α is connected to the other end of the light guide tube 70.

The light source unit 72 has an LED (light emitting diode) (not shown) that emits excitation light α. The excitation light α emitted from the light source unit 72 passes through an excitation light transmission filter 70b and a condenser lens 70a, is reflected by a mirror 68c, and is emitted downward on the mirror holder 68. A rotating spheroid mirror 74 is provided on the lower part of the multiple arms 68a of the mirror holder 68.

The spheroid mirror 74 has a reflecting surface 74a. The reflecting surface 74a corresponds to a portion of the annular surface around the long axis of an ellipsoid formed by rotating an ellipse, the long axis of which is parallel to the Z-axis direction and the short axis of which is parallel to the X-Y plane direction, around the long axis.

In particular, the reflecting surface 74a is located between two focal points (a first focal point _F1 and a second focal point _F2 ) of the spheroid. A rubber ring 76 is in contact with the outer peripheral side surface of the spheroid mirror 74. The spheroid mirror 74 is supported by an annular support ring 78 via the rubber ring 76.

The support ring 78 has a cylindrical portion that protrudes upward. A male thread is formed on the outer side surface 78a of this cylindrical portion. In addition, a female thread is formed in a recess 62b formed in the annular protrusion of the lower part of the reflector fixing portion 62 that corresponds to the outer side surface 78a.

The support ring 78 is fixed to the reflector fixing part 62 by screwing the male thread on the outer side surface 78a into the female thread on the recess 62b. As a result, the spheroid mirror 74 is pressed upward by the support ring 78 via the rubber ring 76.

In addition, the spheroid mirror 74 is pressed downward by the positioning ring 64 via the spacer 66, and is therefore sandwiched in the Z-axis direction by the positioning ring 64 and the support ring 78. The excitation light α is focused at a first focal point _F1 of the spheroid mirror 74.

The first focal point _F1 is set to be a predetermined distance A from the bottom of the spheroid mirror 74. The predetermined distance A is set to, for example, 2.5 mm. The spot diameter of the excitation light α at the first focal point _F1 is set to, for example, 0.6 mm.

When the protective film 19 is present at the first focal point _F1 , the protective film 19 emits fluorescent light β due to the excitation light α focused at the first focal point _F1 . The fluorescent light β incident on the reflecting surface 74a is focused at the second focal point _F2 by the reflecting surface 74a, so that the fluorescent light β can be efficiently guided to the photocathode 54.

Returning now to Figure 1, the coating and cleaning device 2 is provided with a control unit 80 that controls the operation of the spinner table 6, the rotating shaft 14, the liquid resin supply unit 22, the workpiece cleaning unit 30, the rotating shaft 32, the cleaning water spray unit 38, the detection unit 46, etc.

The control unit 80 is composed of a computer including, for example, a processor (processing device) represented by a CPU (Central Processing Unit), a main storage device such as a DRAM (Dynamic Random Access Memory), and an auxiliary storage device such as a flash memory.

The auxiliary storage device stores software including a specific program. The functions of the control unit 80 are realized by operating the processing device and the like in accordance with this software.

The control unit 80 controls the operation of the cleaning water injection unit 38 based on the number of secondary electrons detected by the detection unit 46. Specifically, the control unit 80 detects the thickness of the protective film 19 by converting the number of secondary electrons into the thickness of the protective film 19, while injecting cleaning water 23 onto the surface 15a of the ring frame 15.

Therefore, the ring frame 15 can be washed while checking whether the protective film 19 attached to the surface 15a side of the ring frame 15 has been sufficiently removed. In particular, the control unit 80 causes the washing water injection unit 38 to continue spraying the washing water 23 as long as the thickness of the protective film 19 exceeds the threshold within a predetermined time (e.g., 50 seconds) scheduled as the washing time.

In response to this, if the thickness of the protective film 19 falls below the threshold within a specified time, the control unit 80 stops spraying the cleaning water 23 and terminates cleaning of the ring frame 15 by the cleaning water spray unit 38, even before the specified time has elapsed.

In this way, the ring frame 15 is cleaned while the thickness of the protective film 19 on the surface 15a is detected by the detection unit 46. If the protective film 19 is sufficiently removed, cleaning can be terminated even before the specified time has elapsed. This makes it possible to limit the cleaning time for the ring frame 15.

Next, a method for forming the protective film 19 will be described with reference to Figures 3 and 4. Figure 3 is a flow diagram of a protective film removal method for removing the protective film 19 attached to the surface 15a of the ring frame 15 when covering the surface 11a side of the workpiece 11 with the protective film 19.

First, the workpiece unit 17 is transported by a transport device (not shown) and placed on the holding surface 6a so that the back surface 11b faces the holding surface 6a. At this time, the detection unit 46 is retracted from directly above the holding surface 6a.

Then, the workpiece unit 17 is suction-held on the holding surface 6a (holding step S10). After holding step S10, the spinner table 6 is rotated at a predetermined rotation speed (e.g., a predetermined value between 100 rpm and 300 rpm), and the first nozzle 18 is moved from a retracted position near the inner wall of the chamber 4 to a supply position above the approximate center of the holding surface 6a.

Then, the liquid resin 21 is supplied from the first nozzle 18 to the surface 11a of the workpiece 11, which is rotating together with the spinner table 6, in an amount of, for example, 10 ml to 20 ml (supply step S20). The liquid resin 21 spreads due to centrifugal force and adheres to the surface 15a of the ring frame 15.

Then, while the spinner table 6 is kept rotating at a predetermined rotation speed, the first nozzle 18 is moved to a retracted position and the liquid resin 21 is dried. When the liquid resin 21 is dried, a protective film 19 is formed on the surface 11a of the workpiece 11 and the surface 15a of the ring frame 15 (see FIG. 4).

However, if protective film 19 is present on surface 15a, protective film 19 will adhere to the suction mechanism of the transport device (not shown) when the ring frame 15 is suctioned and transported by the suction mechanism. Furthermore, the inside of the laser processing device will be contaminated by protective film 19 as the transport device moves.

Therefore, after the supply step S20, the detection unit 46 detects the thickness of the protective film 19 formed on the surface 15a (detection step S30). To do this, first, the actuator 44 is positioned above the outer periphery of the holding surface 6a, and the detection unit 46 is moved downward.

As a result, the bottom of the detection unit 46 is positioned at a height of a predetermined distance A from the surface 15a of the ring frame 15. Note that even in the detection step S30, the spinner table 6 continues to rotate at the predetermined rotational speed.

The time interval for detecting the fluorescence β by the detection unit 46 is set appropriately according to the rotation speed and the spot diameter of the excitation light α. When measuring the thickness of the protective film 19, the detection unit 46 measures the thickness of the protective film 19 in an annular region along the circumferential direction of the surface 15a, for example, by focusing the excitation light α at one point on the surface 15a.

However, the actuator 44 may be moved continuously along the guide rail 42 as the spinner table 6 rotates, so that the focused spot of the excitation light α moves in an Archimedes spiral on the surface 15a.

In addition, the actuator 44 may be moved stepwise along the guide rail 42 as the spinner table 6 rotates, thereby moving the focused spot of the excitation light α concentrically on the surface 15a.

When a protective film 19 having approximately the same thickness as that on the surface 11a of the workpiece 11 on which the device is formed is formed on the surface 15a of the ring frame 15, the secondary electron count number exceeds 20× ¹⁰³ (typically, about 30× ¹⁰³ to 50× ¹⁰³ counts).

Therefore, the control unit 80 judges whether the thickness of the protective film 19 detected in the detection step S30 is equal to or less than a threshold value (in this embodiment, the secondary electron count number is equal to or less than 20×10 ³ ) (judgment step S40 ).

If, in the judgment step S40 immediately following the detection step S30, the thickness of the protective film 19 is equal to or less than the threshold value, cleaning of the ring frame 15 (cleaning step S50) is omitted and the flow ends. This shortens the processing time of the workpiece unit 17 and reduces contamination of the transport device and the laser processing device by the protective film 19.

On the other hand, if the thickness of the protective film 19 exceeds the threshold value, cleaning water 23 is sprayed from the third nozzle 36 onto the surface 15a of the ring frame 15 to clean and remove the protective film 19 on the surface 15a (cleaning step S50).

In the cleaning step S50, while the spinner table 6 is rotating at a predetermined rotation speed, the rotating shaft 32 is rotated by a predetermined angle to move the third nozzle 36 from a retracted position near the inner wall of the chamber 4 to a supply position located above and near the boundary between the frame 8 and the porous plate 10.

Figure 4 is a partial cross-sectional side view of the coating and cleaning device 2 in the cleaning step S50. In particular, in the cleaning step S50, the thickness of the protective film 19 is detected by the detection unit 46 while the cleaning water 23 is sprayed diagonally downward outward at a predetermined flow rate (e.g., a predetermined value of 50 ml/min to 100 ml/min) to clean the ring frame 15.

As long as the thickness of the protective film 19 on the surface 15a side of the ring frame 15 exceeds the threshold within the predetermined time (e.g., 50 seconds) scheduled as the cleaning time in the cleaning step S50, the spraying of cleaning water 23 onto the ring frame 15 continues (NO in S60 and NO in S70).

On the other hand, if the thickness of the protective film 19 on the surface 15a side becomes equal to or less than the threshold within the specified time (i.e., if the protective film 19 is sufficiently removed), the flow ends (YES in S60). Also, if the thickness of the protective film 19 on the surface 15a side does not become equal to or less than the threshold but the specified time has elapsed, the flow ends (YES in S70).

If S70 is YES, the control unit 80 operates one or more of the lamps, buzzers, display devices, etc., each electrically connected to the control unit 80, to notify the operator of the alarm through light, sound, or screen display.

When an operator receives an alarm, he or she stops the operation of the coating and cleaning device 2, adjusts the angle of the third nozzle 36, the flow rate of the cleaning water 23, etc., and then operates the coating and cleaning device 2 again after making the adjustments. As a result, the thickness of the protective film 19 on the surface 15a side can be reduced to below the threshold value within a specified time when the ring frame 15 is next cleaned.

In this embodiment, the ring frame 15 can be cleaned while checking whether the protective film 19 attached to the ring frame 15 has been sufficiently removed. Furthermore, if the protective film 19 has been sufficiently removed, the cleaning step S50 can be terminated even before the predetermined time scheduled as the cleaning time has elapsed. Therefore, the cleaning time for the ring frame 15 can be limited.

At the end of the flow shown in FIG. 4, the detection unit 46 is raised and further moved along the guide rail 42 to retreat from directly above the holding surface 6a. At the same time, the spraying of the cleaning water 23 from the third nozzle 36 is stopped, and the rotation of the spinner table 6 is stopped.

Next, the workpiece unit 17 is transported from the spinner table 6 to a chuck table (not shown). Then, the workpiece 11 is subjected to ablation processing using a laser beam having a central wavelength that is absorbed by the workpiece 11 (e.g., 355 nm).

After the ablation process, the workpiece unit 17 is again transported to the coating and cleaning device 2. The workpiece unit 17 is then held by suction on the spinner table 6, and the workpiece unit 17 (workpiece 11) is cleaned.

During cleaning, the first arm 16 is swung by operating the rotating shaft 14, and cleaning water 23 is sprayed from the second nozzle 26 at a predetermined flow rate (e.g., a predetermined value of 200 ml/min to 400 ml/min), while the spinner table 6 is rotated at a predetermined rotational speed (e.g., a predetermined value of 800 rpm to 2000 rpm).

This removes the debris and the protective film 19. The workpiece unit 17 is then transported by the transport device out of the coating and cleaning device 2. Next, a modified example of the arrangement of the detection unit 46 will be described. Figure 5 is a top view illustrating the arrangement of the detection unit 46 and the third nozzle 36.

In the above embodiment, the detection unit 46 is arranged so that the cover 46a faces the center 6b of the holding surface 6a, and the third nozzle 36, the center 6b, and the detection unit 46 are aligned in a straight line when viewed from above.

In other words, the line segment connecting the third nozzle 36 and the center 6b and the line segment connecting the center 6b and the detection unit 46 form an angle of approximately 180°. In this way, by locating the detection unit 46 at a position away from the third nozzle 36, the effect of the cleaning water 23 during cleaning of the ring frame 15 can be reduced.

However, the detection unit 46 may be disposed in an angle range γ from a position where the line segment connecting the third nozzle 36 and the center 6b and the line segment connecting the center 6b and the detection unit 46 form an angle of approximately 180° to a position where the line segment forms an angle of approximately 270°.

If the angle is within the range from approximately 180° to approximately 270°, the effect of the cleaning water 23 from the third nozzle 36 on the detection unit 46 can be sufficiently reduced. In addition, the structures, methods, etc. according to the above embodiments can be modified as appropriate without departing from the scope of the purpose of the present invention.

2: Coating and cleaning device, 4: Chamber, 6: Spinner table (holding table), 6a: Holding surface, 6b: Center, 8: Frame, 10: Porous plate, 12: Rotating shaft, 11: Workpiece, 11a: Front surface, 11b: Back surface, 13: Protective tape (tape)
15: ring frame, 15a: front surface, 15b: back surface, 15c: opening 17: workpiece unit, 19: protective film, 21: liquid resin, 23: cleaning water 14: rotating shaft, 16: first arm, 18: first nozzle, 20: liquid resin supply source 22: liquid resin supply unit, 24: second arm, 26: second nozzle 28: cleaning water supply source, 30: workpiece cleaning unit 32: rotating shaft, 34: third arm, 36: third nozzle, 38: cleaning water spray unit 42: guide rail, 44: actuator, 44a: rod 46: detection unit, 46a: cover 50: photomultiplier tube, 52: bar 5: photocathode, 54: photocathode 56: fixing part, 56a: internal space, 56b: opening 58: connecting part, 58a: opening, 60: fluorescence transmission filter 62: reflecting mirror fixing part, 62a, 62b: recess 64: positioning ring, 64a: outer circumferential side surface, 64b: opening, 66: spacer 68: mirror holding part, 68a: arm part, 68b: recess, 68c: mirror, 68d: opening 70: light guide tube, 70a: condensing lens, 70b: excitation light transmission filter, 72: light source part 74: ellipsoidal mirror, 74a: reflecting surface, 76: rubber ring 78: support ring, 78a: outer side surface, 80: control unit α: excitation light, β: fluorescence, γ: angle range, F ₁ : first focus, F ₂ : second focus, A: distance

Claims (2)

A method for removing a protective film adhering to a surface of a ring frame in a workpiece unit having a ring frame, a tape attached to a back surface of the ring frame, and a workpiece supported by the ring frame via the tape, comprising:
a holding step of holding the workpiece unit on a holding table;
a supplying step of supplying liquid resin onto the surface of the workpiece held by the holding table while rotating the holding table after the holding step;
a detection step of detecting a thickness of the protective film formed on the surface of the ring frame after the supply step;
a cleaning step of spraying cleaning water onto the front surface of the ring frame;
Equipped with
In the cleaning step, the cleaning water is sprayed to clean the ring frame while detecting the thickness of the protective film on the surface of the ring frame ;
A protective film removal method characterized in that in the cleaning step, the spraying of the cleaning water onto the ring frame is continued as long as the thickness of the protective film on the ring frame exceeds a threshold value within a specified time scheduled as the cleaning time in the cleaning step . A coating and cleaning device that coats a liquid resin on a surface of a workpiece in a workpiece unit having a ring frame, a tape attached to a back surface of the ring frame, and a workpiece supported by the ring frame via the tape, and cleans a protective film that has adhered to the surface of the ring frame due to the application of the liquid resin,
a holding table for holding the workpiece unit;
a liquid resin supplying unit that supplies the liquid resin to the surface of the workpiece held by the holding table;
a detection unit for detecting a thickness of the protective film on the surface of the ring frame;
a cleaning water injection unit that injects cleaning water onto the front surface of the ring frame to clean the protective film attached to the ring frame;
a control unit that controls operations of the holding table, the liquid resin supply unit, the detection unit, and the cleaning water spray unit,
the control unit controls an operation of the cleaning water injection unit while detecting the thickness of the protective film on the surface of the ring frame with the detection unit ;
The control unit detects the thickness of the protective film with the detection unit within a predetermined time scheduled as a cleaning time, and causes the cleaning water spraying unit to continue spraying the cleaning water as long as the thickness of the protective film on the ring frame exceeds a threshold value .

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