JP2010012508A - Protective film covering device and laser beam machining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective film covering device with which a protective film covers a wafer surely and economically even when there is difference in level on the surface to be worked of a wafer and metal bump such as an electrode is arranged. <P>SOLUTION: This device is the protective film covering device 30 in which the protective film covers the surface of the wafer W and provided with a spinner table 48 with which the wafer W is sucked, held and rotated and an applying means for applying a liquid resin to the wafer W which is sucked and held on the spinner table 48. The applying means includes a spraying means 68 for jetting the liquid resin by making in spray, an arm 70 for supporting the spraying means 68 and an oscillating means 72 for oscillating the spraying means 68 supported with the arm 70 in the horizontal direction at least in the region from the center part of rotation of the wafer W to the outer peripheral part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a protective film coating apparatus for coating a processed surface of a wafer with a protective film and a laser processing apparatus including the protective film coating apparatus.

  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 is divided into individual devices by a laser processing apparatus, and the divided devices are mobile phones. And widely used in electric devices such as personal computers (see Japanese Patent Application Laid-Open No. 2004-322168).

In the above-mentioned publication, when a laser beam is irradiated on the processed surface of the wafer, the thermal energy concentrates on the irradiated area and the debris is scattered and adheres to the processed surface of the wafer, thereby significantly reducing the quality of the device. A technique is disclosed in which a liquid film is applied to a processed surface of a wafer to form a protective film before laser processing, and then the wafer is laser processed.
JP 2004-322168 A

  However, if there are steps on the processed surface of the wafer or metal bumps such as electrodes are provided, the liquid resin is uniformly applied to the processed surface of the wafer according to the spin coating method of liquid resin disclosed in Patent Document 1. There is a problem that a portion that cannot be applied to the protective film and that is not partially covered with the protective film is generated.

  In addition, although liquid resins such as PVA (polyvinyl alcohol) and PEG (polyethylene glycol) are relatively expensive, the application of the liquid resin by the spin coat method substantially exceeds 90%. There is a problem that the liquid resin is scattered from the processed surface of the wafer and discarded, which is uneconomical.

  The present invention has been made in view of these points, and the object of the present invention is to ensure reliable and economical even if there are steps on the processed surface of the wafer or metal bumps such as electrodes are provided. It is another object of the present invention to provide a protective film coating apparatus capable of coating a protective film.

  Another object of the present invention is to provide a laser processing apparatus provided with a protective film coating apparatus.

  According to the first aspect of the present invention, there is provided a protective film coating apparatus for coating a surface of a wafer with a protective film, wherein the wafer is sucked and held and rotated, and a liquid resin is applied to the wafer sucked and held by the spinner table. An application means for applying, the application means comprising a spray means for spraying the liquid resin in the form of a mist, an arm for supporting the spray means, and a spray means supported by the arm at least for the rotation center of the wafer. A protective film coating apparatus is provided that includes first swinging means that swings in a horizontal direction in a region extending from the first part to the outer peripheral part.

  Preferably, the spray means includes a liquid resin supply passage, an air supply passage, and an injection port through which the liquid resin supply passage and the air supply passage merge to inject a mist-like liquid resin.

  Preferably, the protective film coating apparatus further includes a cleaning means for cleaning the wafer after laser processing and a drying means for drying the wafer after cleaning. Both the cleaning means and the drying means are configured by attaching an injection nozzle for injecting water or air to the tip of the arm, and the injection nozzle supported by the arm is at least horizontally in the region from the rotation center to the outer periphery of the wafer. It is swung.

  According to a fifth aspect of the present invention, there is provided a laser processing apparatus comprising: a chuck table that holds a wafer; and a laser beam irradiation unit that performs processing by irradiating a processing surface of the wafer held by the chuck table with a laser beam. A laser processing apparatus is provided, further comprising the protective film coating apparatus according to any one of claims 1 to 4 for coating a processed surface of a wafer before laser processing with a protective film.

  According to the protective film coating apparatus of the present invention, the liquid resin is atomized and applied to the processed surface of the wafer to coat the protective film, so that there is a step on the processed surface of the wafer, or metal bumps such as electrodes are disposed. Even if it is applied, the processed surface of the wafer can be reliably coated with the protective film.

  Further, when the liquid resin is applied in the form of a mist, the amount of the liquid resin used is reduced to 10% to 15% as compared with application by conventional spin coating, and the economic efficiency is remarkably improved. That is, the amount of the liquid resin required to coat the protective film on the processed surface of the wafer having a diameter of 300 mm is 40-50 mL, but it is reduced to 5-6 mL according to the protective film coating apparatus of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the external appearance of a laser processing apparatus 2 that is provided with the protective film coating apparatus of the present invention and can divide a wafer into individual chips (devices) by laser processing.

  On the front side of the laser processing apparatus 2, operation means 4 is provided for an operator to input instructions to the apparatus such as processing conditions. In the upper part of the apparatus, there is provided a display means 6 such as a CRT for displaying a guidance screen for an operator and an image taken by an imaging means described later.

  As shown in FIG. 2, on the surface of the semiconductor wafer W to be processed, the first street S1 and the second street S2 are formed to be orthogonal to each other, and the first street S1 and the second street S2 are formed. A number of devices D are formed in a region partitioned by.

  The wafer W is attached to a dicing tape T that is an adhesive tape, and the outer peripheral edge of the dicing tape T is attached to an annular frame F. As a result, the wafer W is supported by the annular frame F via the dicing tape T, and a plurality of wafers (for example, 25 sheets) 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 wafer cassette 8 is provided a loading / unloading means 10 for unloading the wafer W 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 loading / unloading means 10, a temporary placement area 12, which is an area on which a wafer to be loaded / unloaded is temporarily placed, is provided. A wafer W is fixed in the temporary placement area 12. Positioning means 14 for positioning to the position of is arranged.

  Reference numeral 30 denotes a protective film coating apparatus according to an embodiment of the present invention, and this 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 area 12 is adsorbed by the transport means 16 and transported to the protective film coating apparatus 30. In the protective film coating apparatus 30, the protective film is coated on the processed surface of the wafer W as will be described in detail later.

  The wafer W whose processing surface is coated with a protective film is attracted by the conveying means 16 and conveyed 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 W, 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.

  A laser beam irradiation unit 24 that irradiates the wafer W held on the chuck table 18 with a laser beam is disposed on the left side of the alignment means 20. 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 laser beam pulse width setting unit 40, and a laser beam wavelength setting unit 42.

  The repetition frequency setting means 38, the laser beam pulse width setting means 40, and the laser beam wavelength setting means 42 constituting the laser beam modulation means 36 are of known forms, and detailed description thereof is omitted in this specification.

  The wafer W that has been subjected to laser processing by the laser beam irradiation unit 24 is gripped by the conveying means 32 that is movable in the Y-axis direction after moving the chuck table 18 in the X-axis direction, and is coated with a protective film that also serves as a cleaning device It is conveyed to the device 30. The protective film coating apparatus 30 cleans the wafer by rotating the wafer W at a low speed (for example, 300 rpm) while spraying water from the cleaning nozzle.

  After cleaning, the wafer W is dried at a high speed (for example, 3000 rpm) by blowing air from the air nozzle, and then the wafer W is adsorbed by the conveying means 16 and returned to the temporary storage area 12, and further carried in and out. By means 10, the wafer W is returned to the original storage location of the wafer cassette 8.

  Next, the protective film coating apparatus 30 according to the embodiment of the present invention will be described in detail with reference to FIGS. 4 to 8. First, referring to FIG. 4, a partially broken perspective view of the protective film coating apparatus 30 is shown.

  The protective film coating apparatus 30 includes a spinner table mechanism 44 and a cleaning water receiving mechanism 46 disposed so as to surround the spinner table mechanism 44. The spinner table mechanism 44 includes a spinner table 48, an electric motor 50 that rotationally drives the spinner table 48, and a support mechanism 52 that supports the electric motor 50 so as to be movable in the vertical direction.

  The spinner table 48 includes a suction chuck 48a made of a porous material, and the suction chuck 48a communicates with suction means (not shown). Accordingly, the spinner table 48 sucks and holds the wafer on the suction chuck 48a by placing the wafer on the suction chuck 48a and applying a negative pressure by suction means (not shown).

  The spinner table 48 is connected to the output shaft 50 a of the electric motor 50. The support mechanism 52 includes a plurality of (three in the present embodiment) support legs 54 and a plurality of (three in the present embodiment) air cylinders 56 respectively connected to the support legs 54 and attached to the electric motor 50. It consists of.

  The support mechanism 52 configured in this manner operates the air cylinder 56 to move the electric motor 50 and the spinner table 48 at the wafer loading / unloading position, which is the ascending position shown in FIG. 5, and the machining position shown in FIG. It can be positioned at a certain work position.

  The cleaning water receiving mechanism 46 is attached to the cleaning water receiving container 58, three support legs 60 (only two are shown in FIG. 4) that support the cleaning water receiving container 58, and the output shaft 50 a of the electric motor 50. Cover member 62.

  As shown in FIGS. 5 and 6, the washing water receiving container 58 includes a cylindrical outer wall 58a, a bottom wall 58b, and an inner wall 58c. A hole 51 into which the output shaft 50a of the electric motor 50 is inserted is provided at the center of the bottom wall 58b, and the inner wall 58c is formed so as to protrude upward from the periphery of the hole 51.

  As shown in FIG. 4, a waste liquid port 59 is provided on the bottom wall 58 b, and a drain hose 64 is connected to the waste liquid port 59. The cover member 62 is formed in a disc shape, and includes a cover portion 62a that protrudes downward from the outer periphery thereof.

  When the electric motor 50 and the spinner table 48 are positioned at the work position shown in FIG. 6, the cover member 62 configured as described above has a gap on the outside of the inner wall 58 c that constitutes the cleaning water receiving container 58. It is positioned to polymerize.

  The protective film coating apparatus 30 includes an application unit 66 that applies a liquid resin to the unprocessed semiconductor wafer held by the spinner table 48. The application means 66 includes a spray nozzle 68 that sprays the liquid resin in a mist toward the processed surface of the wafer before processing held by the spinner table 48, and a generally L-shaped arm 70 that supports the spray nozzle 68; The spray nozzle 68 supported by the arm 70 is composed of an electric motor 72 capable of normal / reverse rotation that swings in the horizontal direction at least in a region extending from the rotation center to the outer periphery of the wafer. The spray nozzle 68 is connected to a liquid resin supply source (not shown) via an arm 70.

  The protective film coating apparatus 30 also serves as a cleaning apparatus for cleaning the wafer after laser processing. Therefore, the protective film coating apparatus 30 includes cleaning water supply means 74 and air supply means 76 for cleaning the processed wafer held on the spinner table 48.

  The cleaning water supply means 74 includes a cleaning water nozzle 78 that ejects cleaning water toward the processed wafer held by the spinner table 48, an arm 80 that supports the cleaning water nozzle 78, and a cleaning supported by the arm 80. The electric motor 82 is configured to be able to rotate normally and reversely so as to swing the water nozzle 78. The cleaning water jet nozzle 78 is connected to a cleaning water supply source (not shown) via the arm 80.

  The air supply means 76 swings the air nozzle 84 that ejects air toward the cleaned wafer held by the spinner table 48, the arm 86 that supports the air nozzle 84, and the air nozzle 84 that is supported by the arm 86. An electric motor (not shown) that moves forward and reverse is provided. The air nozzle 84 is connected to an air supply source (not shown) via an arm 86.

  As shown in FIG. 7, the spray nozzle 68 and the arm 70 are integrally formed. The spray nozzle 68 includes, for example, a liquid resin supply passage 88 connected to a 0.2 MPa liquid resin supply source 90, an air supply passage 92 connected to, for example, a 0.4 MPa air supply source 94, a liquid resin supply passage 88, and air. The supply passage 92 includes an injection port 96 that joins and injects a mist-like liquid resin.

  Next, the operation of the protective film coating apparatus 30 configured as described above will be described. The semiconductor wafer before processing is transported to the spinner table 48 of the protective film coating apparatus 30 by the turning motion of the wafer transport means 16, and is sucked and held by the suction chuck 48a.

  At this time, the spinner table 48 is positioned at the wafer loading / unloading position shown in FIG. 5, and the spray nozzle 68, the washing water nozzle 78, and the air nozzle 84 are located above the spinner table 48 as shown in FIGS. It is located in the standby position isolated from

  If the unprocessed wafer is held on the spinner table 48 of the protective film coating apparatus 30, a protective film coating process is performed in which a liquid resin is sprayed on the surface of the wafer W to be processed to cover the protective film.

  To carry out the protective film coating step, first, the spinner table 48 is positioned at the working position as shown in FIGS. 6 and 8, and the spinner table 48 is moved in the direction of arrow A at 10 to 100 rpm (preferably 30 to 50 rpm). While rotating, the spray nozzle 68 is positioned on the outer periphery of the wafer W, and sprays a mist-like liquid resin to reach the center of the wafer W (for example, about 4/5 of the wafer radius) over about 40 seconds. After that, it returns to the outer periphery of the wafer W over about 40 seconds while spraying a mist-like liquid resin from the center of the wafer, and as shown by an arrow B, a protective film is formed on the processing surface of the wafer by one reciprocation of the spray nozzle 68 Cover. Note that when the spray nozzle 68 is moved to the center, the film thickness at the center increases, so it is folded back before the center.

  The amount of the liquid resin required to coat the processed surface of the 300 mm diameter wafer with the 10 μm thick protective film by the liquid resin spray coating method of this embodiment was about 5 to 6 mL. For comparison, according to the conventional spin coat coating method, the amount of liquid resin needs 40-50 mL, and according to the spray coating method of the liquid resin of the present invention, the amount of liquid resin used is 10% to the conventional amount. It was found that the economy was significantly improved with a marked decrease of 15%.

  Instead of reciprocating the spray nozzle 68 once as indicated by the arrow B while spraying the liquid resin, it is possible to adopt a method in which the spray of the liquid resin is terminated from the outer periphery of the wafer W to the center of the wafer over about 80 seconds. It is. Alternatively, the spray nozzle 68 may be swung from the outer peripheral portion of the wafer through the center to another outer peripheral portion in about 80 seconds. In this case, it is preferable to pass the spray nozzle 68 at a relatively high speed in the center of the wafer.

  The liquid resin applied to the processed surface of the wafer by the spray nozzle 68 is cured with time to form a protective film 98 on the surface of the semiconductor wafer W as shown in FIG. The thickness of the protective film 98 is preferably about 0.5 to 10 μm.

  The liquid resin forming the protective film 98 is preferably a water-soluble resist such as PVA (polyvinyl alcohol) PEG (polyethylene glycol), PEO (polyethylene oxide), or the like.

  If the protective film 98 is coated on the surface of the semiconductor wafer W by the protective film coating process, the spinner table 48 is positioned at the wafer loading / unloading position shown in FIG. Is released.

  The wafer W on the spinner table 48 is transported to the chuck table 18 by the wafer transport means 16 and sucked and held by the chuck table 18. Further, the chuck table 18 moves in the X-axis direction, and the wafer W is positioned immediately below the imaging means 22.

  Image processing such as pattern matching for aligning the condenser 28 of the laser beam irradiation unit 24 that irradiates the laser beam and the street S is performed by imaging the processing area of the wafer W with the imaging unit 22, The alignment of the laser beam irradiation position is performed.

  Thus, if the street S1 or S2 of the wafer W held on the chuck table 18 is detected and the alignment of the laser beam irradiation position is performed, the condenser that irradiates the chuck table 18 with the laser beam. It moves to the laser beam irradiation region where 28 is located, and irradiates the laser beam through the protective film 98 from the condenser 28 along the street S1 or S2 of the wafer W.

  In the laser beam irradiation process, as shown in FIG. 10, the laser beam irradiation unit 24 that irradiates the laser beam from the condenser 28 toward the predetermined street S through the protective film 98 from the surface side that is the processing surface of the wafer W. While irradiating the pulse laser beam, the chuck table 18 is moved in the X-axis direction at a predetermined feed rate (for example, 100 mm / second).

  The laser processing conditions are as follows, for example.

Light source: YAG laser Wavelength: 355 nm (third harmonic of YAG laser)
Output: 3.0W
Repetition frequency: 20 kHz
Condensing spot diameter: 1.0 μm
Feeding speed: 100 mm / second The wafer W is divided along the street S by performing the laser beam irradiation process. At this time, even if the debris 100 is generated by the irradiation of the laser beam as shown in FIG. 10, the debris 100 is blocked by the protective film 98 and does not adhere to the electronic circuit and the bonding pad of the device D.

  When the semiconductor wafer W is divided into the individual devices D in this way, the chuck table 18 is first returned to the position where the wafer W is sucked and held, and here, the suction holding of the wafer W is released. Then, the wafer W is transported to the spinner table 48 of the protective film forming apparatus 30 by the transport means 32 and sucked and held by the suction chuck 48a.

  At this time, the spray nozzle 68, the washing water nozzle 78, and the air nozzle 84 are positioned at a standby position separated from above the spinner table 48 as shown in FIGS.

  Then, the wafer W is rotated at a low speed (for example, 300 rpm) while spraying cleaning water composed of pure water and air from a cleaning water nozzle 78 connected to the pure water source and the air source in substantially the same configuration as the spray nozzle 68. The wafer W is cleaned by

  At this time, like the spray nozzle 68 shown in FIG. 8, the washing water nozzle 78 injects washing water while being swung in the horizontal direction in the region from the outer periphery of the wafer to the rotation center. The cleaning nozzle 78 reaches the center of the wafer and cleans the entire surface.

  As a result, since the protective film 98 coated on the surface of the wafer W is formed of a water-soluble resin, the protective film 98 can be easily washed away as shown in FIG. Debris 100 is also removed.

  When the cleaning process is completed, a drying process is performed. That is, the cleaning water nozzle 78 is positioned at the standby position, and the outlet of the air nozzle 84 is positioned above the outer peripheral portion of the wafer W held on the spinner table 48.

  Then, air is ejected from the air nozzle 84 toward the wafer W held on the spinner table 48 while rotating the spinner table 48 at, for example, 3000 rpm. At this time, the air ejected from the air nozzle 84 is swung within a swing range from a position where it hits the outer peripheral portion of the wafer W held by the spinner table 48 to a position where it hits the center portion. As a result, the surface of the wafer W is dried.

  After the wafer W is dried, the wafer W is adsorbed by the conveying means 16 and returned to the temporary storage area 12, and the wafer W is returned to the original storage location of the wafer cassette 8 by the carry-in / out means 10.

It is an external appearance perspective view of a laser processing apparatus. It is a perspective view which shows the wafer integrated with the flame | frame. It is a block diagram of a laser beam irradiation unit. It is a partially broken perspective view of a protective film coating apparatus. It is a longitudinal cross-sectional view of the protective film coating apparatus in a state where the spinner table is raised. It is a longitudinal cross-sectional view of the protective film coating apparatus in a state where the spinner table is lowered. It is a longitudinal cross-sectional view of a spray nozzle. It is explanatory drawing explaining the rocking | fluctuation range of a spray nozzle. It is an expanded sectional view of the semiconductor wafer with which the protective film was coat | covered. It is explanatory drawing which shows a laser beam irradiation process. It is an expanded sectional view of a wafer in the state where a protective film was removed by the washing process.

Explanation of symbols

2 Laser processing device 18 Chuck table 24 Laser beam irradiation unit 28 Condenser 30 Protective film coating device 48 Spinner table 66 Liquid resin coating means 68 Spray nozzle 70 Arm 72 Electric motor 74 Cleaning means 78 Washing water nozzle 76 Drying means 84 Air nozzle 88 Liquid resin supply passage 92 Air supply passage 96 Injection port

Claims (5)

A protective film coating apparatus for coating a surface of a wafer with a protective film,
A spinner table that holds and rotates the wafer, and
An application means for applying a liquid resin to the wafer sucked and held by the spinner table;
The coating means includes a spray means for spraying liquid resin in the form of a mist, an arm for supporting the spray means, and a spray means supported by the arm at least in a region extending from the rotation center to the outer periphery of the wafer. A protective film coating apparatus comprising: first swinging means swinging in a direction.   The spray means includes a liquid resin supply passage, an air supply passage, and an injection port through which the liquid resin supply passage and the air supply passage merge to inject a mist-like liquid resin. The protective film coating apparatus according to claim 1.   A cleaning water nozzle that ejects the cleaning liquid, a second arm that supports the cleaning water nozzle, and the cleaning water nozzle supported by the second arm in the horizontal direction at least in a region from the rotation center to the outer periphery of the wafer. The protective film coating apparatus according to claim 1, further comprising a cleaning unit having a second swinging unit that swings.   An air nozzle that injects air, a third arm that supports the air nozzle, and the air nozzle that is supported by the third arm swings in a horizontal direction at least in a region from the rotation center to the outer periphery of the wafer. The protective film coating apparatus according to claim 3, further comprising a drying unit having a third swinging unit. A laser processing apparatus comprising: a chuck table that holds a wafer; and a laser beam irradiation unit that performs processing by irradiating a processing surface of the wafer held by the chuck table with a laser beam,
A laser processing apparatus, further comprising the protective film coating apparatus according to any one of claims 1 to 4, which coats the processed surface of the wafer before laser processing with a protective film.

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