JP6173192B2 - Liquid ejector - Google Patents

Description

  The present invention relates to a liquid ejecting apparatus that ejects liquid onto an upper surface of a wafer.

  A wafer such as a silicon wafer or a sapphire wafer formed on the surface by dividing a plurality of devices such as IC, LSI, LED, etc. by dividing lines (streets) is divided into individual devices by a processing apparatus. Widely used in various electric devices such as mobile phones and personal computers.

  A dicing method using a cutting device called a dicer is widely used for dividing the wafer. In the dicing method, a wafer is cut by cutting a wafer into a wafer by rotating a cutting blade having a thickness of about 30 μm by solidifying diamond or other abrasive grains with a metal or resin at a high speed of about 30000 rpm. And split.

  On the other hand, in recent years, a laser processing groove is formed by irradiating a wafer with a pulsed laser beam having a wavelength that is absorptive to the wafer, and an external force is applied to the wafer by a braking device to perform a wafer along the laser processing groove. Has been proposed (see, for example, Japanese Patent Laid-Open No. 10-305420).

  Laser processing grooves formed by a laser processing apparatus can increase the processing speed compared to a dicing method using a dicer, and relatively easily process even a wafer made of a material having high hardness such as sapphire or SiC. be able to. In addition, since the processing groove can be made to have a narrow width of, for example, 10 μm or less, the amount of devices taken per wafer can be increased as compared with the case of processing by the dicing method.

  However, when a wafer is irradiated with a pulse laser beam, debris is generated due to concentration of thermal energy in the region irradiated with the pulse laser beam. When this debris adheres to the device surface, there arises a problem that the quality of the device is lowered.

  Therefore, for example, in Japanese Patent Application Laid-Open No. 2004-322168, in order to solve such a problem caused by debris, water processing such as PVA (polyvinyl alcohol) and PEG (polyethylene glycol) is applied to the processed surface of the wafer. There has been proposed a laser processing apparatus in which a protective resin is applied to coat a protective film and a wafer is irradiated with a pulsed laser beam through the protective film.

JP-A-10-305420 JP 2004-322168 A

  However, if the wafer is integrated with the annular frame via the dicing tape at the stage of applying the water-soluble resin, the annular frame is on the outer peripheral side of the wafer, so that it was dropped on the wafer when the spinner table was rotated. Water-soluble resin scatters and adheres to the upper surface of the annular frame.

  When the wafer is transported, the annular frame is transported in a state of being sucked by the suction pad of the transport device. Therefore, when the suction is released and the wafer is placed on a certain place, the annular frame is caused by the adhesiveness of the water-soluble resin. There is a problem that it may not be detached from the suction pad, and the water-soluble resin adhering to the upper surface of the annular frame is washed and removed.

  When cleaning the upper surface of the annular frame, the cleaning water is sprayed from the cleaning water nozzle, but when the cleaning water nozzle is moved after the cleaning is completed, water droplets of the cleaning water from the tip of the cleaning water nozzle onto the wafer. And the water-soluble resin applied to the wafer is dissolved.

  Also, when applying a water-soluble resin to the upper surface of the wafer, the water-soluble resin is dropped from the resin supply nozzle onto the wafer surface, and the spinner table is rotated to uniformly apply the water-soluble resin to the wafer surface. However, there is also a problem that the uniformity of the resin film on the wafer surface is impaired due to a drop of water-soluble resin dropping from the tip of the resin supply nozzle after the application.

  In order to cope with such a problem, a so-called so-called drop of liquid droplets is prevented by applying a negative pressure to a path communicating with the nozzle for supplying the liquid to suck the liquid droplets formed at the nozzle tip into the nozzles and preventing the liquid droplets from dropping unexpectedly. A suckback is taking place.

  In order to perform suckback, a suckback valve is provided between the nozzle and the solenoid valve that opens and closes the path communicating with the nozzle, and after the solenoid valve is closed, the suckback valve is operated and a part of the path is opened. And the droplet formed at the tip of the nozzle is sucked into the nozzle. However, the provision of the suck back valve leads to high costs and complicated control of the apparatus.

  The present invention has been made in view of these points, and an object of the present invention is to provide a liquid ejecting apparatus that can prevent an unexpected drop of liquid droplets from the nozzle tip without incurring high costs. is there.

  According to the present invention, there is provided a liquid ejecting apparatus that ejects liquid onto the upper surface of a wafer, the spinner table that rotates while holding the wafer, the rotation driving means that rotates the spinner table, and the wafer held by the spinner table. A liquid ejection nozzle that ejects liquid to the liquid ejection source, a liquid supply source that supplies liquid to the liquid ejection nozzle, a liquid conveyance path that connects the liquid supply source and the liquid ejection nozzle, and a liquid conveyance path. A pump for sending liquid from the liquid supply source toward the liquid ejecting nozzle; an electromagnetic valve disposed between the pump and the liquid ejecting nozzle in the liquid transport path; and opening and closing the liquid transport path; An aspirator that is disposed between the valve and the liquid jet nozzle and generates a negative pressure when liquid flows through the liquid transport path, and the aspirator includes: One end and a second end communicate with the liquid transport path, and a main flow path having a throttle portion between the first end and the second end, and a branch from the throttling portion of the main flow path branch the liquid into the main flow path. A negative pressure generating unit that generates a negative pressure by flowing, and when the negative pressure is generated in the negative pressure generating unit, the negative pressure generating unit is sucked inside and contracts, and the negative pressure generating unit When the negative pressure generated in the pressure generator is released, the fluid bag communicates with an elastic bag that expands and recovers, and the liquid flow is stopped by the closing operation of the electromagnetic valve. When the negative pressure is no longer generated at the negative pressure generator, the liquid is sucked from the liquid ejection nozzle side of the liquid transport path toward the liquid bag when the contracted state is restored to the shape before contraction. A liquid ejecting apparatus is provided.

  According to the present invention, since the liquid bag communicating with the negative pressure generating part of the aspirator is disposed, the liquid bag is contracted when the flow of the fluid stops and the negative pressure generating part of the aspirator disappears. In this case, the liquid can be sucked from the liquid ejecting nozzle side of the liquid transport path toward the liquid bag, so that an unexpected droplet from the liquid ejecting nozzle without incurring high costs. Can prevent falling.

It is a perspective view of a laser processing apparatus. It is a perspective view of the frame unit of the form which supported the wafer with the annular frame via the dicing tape. It is a block diagram of a laser beam irradiation unit. It is a perspective view of a protective film coating apparatus. It is a perspective view of the protective film coating apparatus of the state which has apply | coated water-soluble resin on the wafer. 6A is a schematic view of a liquid ejecting apparatus according to an embodiment of the present invention, and FIG. 6B is a cross-sectional view of an aspirator disposed in the liquid ejecting apparatus of FIG. 6A. It is a figure explaining the effect | action of the liquid ejecting apparatus which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, there is shown a perspective view of a laser processing apparatus 2 that includes a protective film coating apparatus (resin coating apparatus) that coats a surface of a wafer with a protective film made of a water-soluble resin and can perform laser processing on the wafer. It is shown.

  On the front side of the laser processing apparatus 2, an operation panel 4 is provided for an operator to input instructions to the apparatus such as processing conditions. In the upper part of the apparatus, a display monitor 6 such as a CRT on which a guide screen for an operator and an image captured by an imaging unit described later are displayed is provided.

  As shown in FIG. 2, a plurality of division lines (streets) 13 are formed in a lattice pattern on the surface of the semiconductor wafer 11 to be processed, and each region partitioned by the division lines 13 that intersect each other is formed in each region. A device 15 such as an IC or LSI is formed.

  The wafer 11 is attached to a dicing tape T that is an adhesive tape, and the outer peripheral portion of the dicing tape T is attached to and integrated with an annular frame F to form a frame unit 17. Thus, the wafer 11 is supported by the annular frame F via the dicing tape T, and a plurality of wafers are accommodated in the wafer cassette 8 shown in FIG. The wafer cassette 8 is placed on a cassette elevator 9 that can move up and down.

  Behind the cassette elevator 9 is disposed a loading / unloading unit 10 for unloading the wafer 11 before laser processing from the wafer cassette 8 and loading the processed wafer into the wafer cassette 8.

  Between the wafer cassette 8 and the carry-in / out unit 10, a temporary placement area 12, which is an area on which a wafer to be carried in / out, is temporarily placed, is provided. A pair of alignment bars 14 for aligning the center in the axial direction are provided.

  Reference numeral 30 denotes a protective film coating apparatus. The protective film coating apparatus 30 also serves as a cleaning apparatus for cleaning the processed wafer. In the vicinity of the temporary placement region 12, a transport unit 16 having a turning arm that sucks and transports the frame F integrated with the wafer W is disposed.

  The wafer W carried out to the temporary placement region 12 is adsorbed by the transport unit 16 and transported to the protective film coating apparatus 30. In the protective film coating apparatus 30, the processed surface of the wafer 11 is coated with a protective film as will be described in detail later.

  The wafer 11 whose processing surface is coated with a protective film is sucked by the transport unit 16 and transported onto the chuck table 18 and is sucked by the chuck table 18, and the frame F is fixed by a plurality of fixing means (clamps) 19. As a result, the chuck table 18 is held.

  The chuck table 18 is configured to be rotatable and reciprocally movable in the X-axis direction. Above the movement path of the chuck table 18 in the X-axis direction, an alignment unit 20 that detects a street of the wafer W to be laser processed. Is arranged.

  The alignment unit 20 includes an imaging unit 22 that images the surface of the wafer 11, and can detect a street to be laser processed by image processing such as pattern matching based on an image acquired by imaging. The image acquired by the imaging unit 22 is displayed on the display unit 6.

  On the left side of the alignment unit 20, a laser beam irradiation unit 24 that irradiates the wafer W held on the chuck table 18 with a laser beam is disposed. The casing 26 of the laser beam irradiation unit 24 accommodates laser beam oscillation means, which will be described in detail later, and a condenser 28 that condenses the laser beam on the wafer to be processed at the tip of the casing 26. Is installed.

  As shown in the block diagram of FIG. 3, a laser beam oscillating means 34 and a laser beam modulating means 36 are disposed in the casing 26 of the laser beam irradiation unit 24.

  As the laser beam oscillation means 34, a YAG laser oscillator or a YVO4 laser oscillator can be used. The laser beam modulating unit 36 includes a repetition frequency setting unit 38, a pulse width setting unit 40, and a wavelength setting unit 42. The repetition frequency setting means 38, the pulse width setting means 40, and the wavelength setting means 42 constituting the laser beam modulating means 36 are of a well-known form and will not be described in detail in this specification.

  The wafer 11 that has been subjected to laser processing by the laser beam irradiation unit 24 is covered with a protective film that is also used as a cleaning device while being held by a transport unit 32 that is movable in the Y-axis direction after moving the chuck table 18 in the X-axis direction. It is conveyed to the device 30. In the protective film coating apparatus 30, the wafer 11 is cleaned by rotating the wafer 11 at a low speed (for example, 800 to 1000 rpm) while jetting water from the cleaning nozzle.

  After cleaning, the wafer 11 is dried by rotating the wafer 11 at a high speed (for example, 1500 to 2000 rpm) to dry the wafer 11, and then the wafer 11 is sucked by the transport unit 16 and returned to the temporary storage area 12. The wafer 11 is returned to the original storage location of the wafer cassette 8 by the insertion unit 10.

  Next, a protective film coating apparatus (liquid injection apparatus) according to an embodiment of the present invention in which a water-soluble resin (liquid) is sprayed onto the upper surface of the wafer to coat the upper surface of the wafer with a protective film will be described with reference to FIGS. explain. Referring to FIG. 4, a perspective view of the protective film coating apparatus 30 is shown. FIG. 5 is a perspective view of the protective film coating apparatus 30 in a state where a water-soluble resin is sprayed onto the upper surface of the wafer.

  The protective film coating apparatus 30 includes a spinner table 46 and a purified water receiving container 48 disposed so as to surround the spinner table 46. The purified water receiving container 48 is supported by three support legs 64 (only two are shown in FIGS. 4 and 5).

  The spinner table 46 includes a suction holding unit 50 made of a porous material such as porous ceramics, and a metal frame 52 surrounding the suction holding unit 50. The suction holding unit 50 is selectively communicated with suction means (not shown).

  Therefore, the spinner table 46 sucks and holds the wafer 11 on the suction holding portion 50 via the dicing tape T by placing the frame unit 17 on the spinner table 46 and applying negative pressure by suction means (not shown). To do. The annular frame F is fixed by a clamp (not shown).

  The spinner table 46 is connected to the output shaft 56 of the electric motor 54. The support mechanism 58 includes a plurality of support legs 60 and a plurality of air cylinders 62 connected to the support legs 60 and attached to the electric motor 54.

  The support mechanism 58 configured in this way operates the air cylinder 62 to move the electric motor 54 and the spinner table 46 to the wafer loading / unloading position, which is the lifting position, and the lowering position shown in FIGS. 4 and 5. It can be positioned at the work position.

  The protective film coating apparatus 30 sprays air, a resin spray nozzle 66 that sprays a water-soluble resin onto the unprocessed semiconductor wafer 11 held by the spinner table 46, a cleaning water spray nozzle 68 that sprays cleaning water, and air. An air injection nozzle 70 is provided.

  The resin injection nozzle 66, the washing water injection nozzle 68, and the air injection nozzle 70 are rotated by a motor (not shown) between the retracted position shown in FIG. 4 and the work position positioned above the wafer 11 held by the spinner table 46. Moved.

  Referring to FIG. 5, the frame unit 17 is sucked and held by the spinner table 46, the resin injection nozzle 66 is rotated to the working position above the wafer 11, and water-soluble resin is injected onto the wafer 11 from the resin injection nozzle 66. The perspective view of the protective film coating apparatus 30 of the state which is in the state is shown.

  As the water-soluble resin forming the protective film, a water-soluble resist such as PVA (polyvinyl alcohol), PEG (polyethylene glycol), PEO (polyethylene oxide), or the like is desirable.

  After water-soluble resin is sprayed from the resin spray nozzle 66 onto the wafer 11, the electric motor 54 is driven to rotate the spinner table 46 at, for example, 2000 rpm, and the sprayed water-soluble resin is spin coated on the entire surface of the wafer 11. To do. Since the frame unit 17 is rotated at such a high speed, the water-soluble resin is also applied onto the annular frame F.

  After spin-coating the water-soluble resin, the spinner table 46 is driven at a low speed of 100 to 200 rpm while spraying cleaning water composed of pure water and air from the cleaning water spray nozzle 68 connected to the pure water source and the air source onto the annular frame F. The annular frame F is washed by rotating at.

  After the water-soluble resin is spin-coated on the wafer 11 and the annular frame F is cleaned, the annular frame 17 of the frame unit 17 is adsorbed by the conveyance unit 32 and the frame unit 17 is conveyed to the chuck table 18 to be chucked. The wafer 11 is sucked and held by the table 18 via the dicing tape T, and the annular frame F is clamped and fixed by the clamp 19. The water-soluble resin spin-coated on the wafer 11 is cured after a while, and the surface of the wafer 11 is covered with a protective film.

  Next, with reference to FIGS. 6 and 7, a liquid ejecting apparatus 71 that generalizes the features of the present invention that can be applied to the protective film coating apparatus 30 will be described. As shown in FIG. 6 (A), the liquid ejecting apparatus 71 has liquid (water-soluble) in a liquid supply source 72 that contains a liquid 76 such as a water-soluble resin in a container 74 and a wafer 11 that is held by a spinner table 46. A liquid injection nozzle (resin injection nozzle) 66 that injects (resin), and a liquid conveyance path 80 that connects the liquid supply source 72 and the liquid injection nozzle 66.

  In the liquid conveyance path 80, a pump 78 that sends liquid from the liquid supply source 72 toward the liquid ejection nozzle 66, and a liquid conveyance path 80 that is disposed between the pump 78 and the liquid ejection nozzle 66 in the liquid conveyance path 80. An electromagnetic valve 82 that opens and closes, and an aspirator 84 that is disposed between the electromagnetic valve 82 and the liquid jet nozzle 66 and generates a negative pressure when the liquid flows through the liquid conveyance path 80 are interposed.

  As shown in FIG. 6B, the aspirator 84 has a first end 84a and a second end 84b communicating with the liquid transporting path 80, and a throttle portion 90 between the first end 84a and the second end 84b. A main flow path 88 and a negative pressure generating section 92 that branches from the throttle section 90 of the main flow path 88 and generates a negative pressure when a liquid flows through the main flow path 88 are included. The negative pressure generating part 92 is connected to the liquid bag 86 as shown in FIG. In the liquid bag 86, the same liquid 76 as the liquid 76 of the liquid supply source 72 is accommodated.

  Next, the operation of the liquid ejecting apparatus 71 according to the embodiment of the present invention will be described with reference to FIGS. 7 (A) to 7 (C). First, as illustrated in FIG. 7A, when the electromagnetic valve 82 is switched to the communication position, the liquid transport path 80 is communicated with the liquid supply source 72.

  The pump 78 is operated to send the liquid from the liquid supply source 72 to the liquid jet nozzle 66 via the liquid transport path 80 and jet the liquid from the liquid jet nozzle 66. At this time, since the liquid passes through the main flow path 88 of the aspirator 84, a negative pressure is generated in the negative pressure generating section 92 by the throttle section 90, and the liquid 76 in the liquid bag 86 is sucked up.

  As shown in FIG. 7B, when the electromagnetic valve 82 is switched to the cutoff position, the ejection of the liquid 76 from the liquid ejecting nozzle 66 is stopped, and the droplet 94 may remain at the tip of the liquid ejecting nozzle 66. . At this time, the liquid bag 86 is contracted.

  After a while, since no negative pressure acts on the liquid bag 86, the liquid bag 86 is restored (expanded) to its original position as shown in FIG. As a result, the liquid in the liquid transport path 80 between the aspirator 84 and the liquid ejecting nozzle 66 is sucked into the liquid bag 86, so that the droplet 94 that hangs down from the tip of the liquid ejecting nozzle 66 is removed. Sucked in. Therefore, even if the liquid ejecting nozzle 66 is moved in this state, the liquid 94 does not fall from the tip of the liquid ejecting nozzle 66.

  According to the liquid ejecting apparatus 71 described above, for example, the liquid ejecting nozzle 66 is employed as the resin ejecting nozzle, the water ejecting resin is ejected from the resin ejecting nozzle 66 onto the wafer 11, and the spinner table 46 is rotated to rotate the water soluble resin. Is spin-coated on the upper surface of the wafer 11, and when the electromagnetic valve 82 is switched to the blocking position and the injection of the water-soluble resin from the resin injection nozzle 66 is stopped, water-soluble resin droplets are discharged from the tip of the resin injection nozzle 66. It is possible to prevent the problem that the uniformity of the resin film that is dropped and spin-coated on the wafer surface is impaired.

  In addition, when the liquid ejecting device 71 is applied to the cleaning water spray nozzle 68, water droplets of cleaning water from the tip of the cleaning water spray nozzle 68 when the cleaning water spray nozzle 68 is moved after the cleaning of the annular frame F is completed. Can be prevented from falling on the wafer 11 and dissolving the water-soluble resin applied to the wafer 11.

T dicing tape F annular frame 11 semiconductor wafer 17 frame unit 18 chuck table 24 laser beam irradiation unit 28 condenser 30 protective film coating device 46 spinner table 54 electric motor 66 resin injection nozzle (liquid injection nozzle)
68 Washing water injection nozzle 70 Air nozzle 71 Liquid injection device 72 Liquid supply source 78 Pump 80 Liquid conveyance path 82 Solenoid valve 84 Aspirator 86 Liquid bag 88 Main flow path 90 Restriction section 92 Negative pressure generation section 94 Liquid droplet

Claims (4)

A liquid ejecting apparatus that ejects liquid onto the upper surface of a wafer,
A spinner table that rotates while holding a wafer, a rotation drive unit that rotates the spinner table, a liquid ejecting nozzle that ejects liquid onto a wafer held by the spinner table, and a liquid that supplies liquid to the liquid ejecting nozzle A supply source, a liquid transport path that connects the liquid supply source and the liquid ejection nozzle, a pump that is disposed in the liquid transport path and feeds the liquid from the liquid supply source toward the liquid ejection nozzle, and the liquid An electromagnetic valve disposed between the pump and the liquid jet nozzle in the transport path and opening and closing the liquid transport path; and a liquid disposed between the solenoid valve and the liquid jet nozzle and passing through the liquid transport path. An aspirator that generates negative pressure by flowing,
The aspirator includes a main channel having a first end and a second end communicating with the liquid transport path and having a throttle portion between the first end and the second end, and a branch from the throttle portion of the main channel. A negative pressure generating part that generates a negative pressure by flowing a liquid through the main flow path,
The negative pressure generating portion is sucked and contracted when a negative pressure is generated at the negative pressure generating portion, and expands when the negative pressure generated at the negative pressure generating portion is released. Communicate with the elastic bag to restore
When the liquid flow is stopped by the closing operation of the electromagnetic valve and the generation of the negative pressure in the negative pressure generating portion is stopped, the liquid bag is used when the liquid bag is restored from the contracted state to the shape before the contraction. A liquid ejecting apparatus, wherein the liquid is sucked from the liquid ejecting nozzle side of the transport path toward the liquid bag.   The liquid ejecting apparatus according to claim 1, further comprising a plurality of the liquid ejecting nozzles and a plurality of liquid supply sources communicating with the liquid ejecting nozzles.   The liquid ejecting apparatus according to claim 2, wherein the liquid supplied from the liquid supply source is water.   The liquid ejecting apparatus according to claim 2, wherein the liquid supplied from the liquid supply source is a water-soluble resin.

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