JP2014136238A - Laser beam machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of such trouble that a large quantity of wafers to which much dust (debris) adheres are produced, since it can be easily and early found that the dust (the debris) is not sufficiently discharged, even during machining, with a simple structure of installing a cleanliness monitoring monitor in a machining chamber.SOLUTION: In a laser beam machining device 2, a laser beam irradiation unit 24 further comprises a suction block (dust discharge means) 43 for sucking and discharging the debris (the dust) 5 produced in the vicinity of a machining point by irradiation of a laser beam LB. In a machining chamber 27, a cleanliness monitoring monitor 40 for measuring a quantity of the debris 5 scattered in the air in the machining chamber 27 and outputting a measurement result, is disposed. The cleanliness monitoring monitor 40 outputs a fact that the dust of a prescribed value or more is measured, and thereby, it is possible to confirm that suction and discharge of the dust produced in the vicinity of the machining point is insufficient.

Description

  The present invention relates to a laser processing apparatus, and more particularly, to a laser processing apparatus that performs ablation processing.

  Conventionally, a semiconductor wafer on which ICs, LSIs, etc. are formed and a sapphire wafer on which LEDs are formed are divided into individual devices by irradiating a laser beam with a laser processing apparatus and forming grooves on the surface. Processing steps are known. The divided devices are used for manufacturing electric devices such as mobile phones, PCs, and LED lights.

  It is known that when a semiconductor wafer or sapphire wafer is irradiated with a laser beam in a processing process using such a laser processing apparatus, fine debris called debris is generated and scattered, and this debris is scattered on the surface of the device. Deposition is known to degrade device quality.

  As a countermeasure against this debris, a protective film is applied to the surface of the device in advance, laser processing is performed, and the debris adhering to the protective film together with the protective film is washed and removed, along the optical axis of the objective lens There has been proposed a laser processing apparatus that includes a jet port for jetting air and sucks debris from around the jet port to prevent the debris from accumulating on the surface of the device (see, for example, Patent Documents 1 to 3). ).

JP 2007-69249 A JP 2011-189400 A JP 2006-032419 A

  However, for example, even if measures to suck debris are taken, it is difficult to visually check the flow of airflow. There is a concern that a situation may occur in which all debris that should be discharged is scattered in the processing chamber without being discharged.

  The occurrence of this situation is found only after the processing is actually performed and it is discovered that a large amount of debris has adhered to the processed wafer. It was something that could not be prevented. That is, during processing, it was impossible to grasp the occurrence state of debris and the suction / discharge state.

  Further, when the debris is filled in the apparatus, there is a problem that optical parts, drive system parts and the like are contaminated.

  The present invention has been made in view of these points, and the object of the present invention is to provide a novel technique that makes it possible to grasp the state of occurrence of debris and the state of suction and discharge during laser processing. Is to provide.

  According to the first aspect of the present invention, a laser beam is irradiated by irradiating the surface of the workpiece held by the chuck table with a laser beam having a wavelength that has an absorptivity with respect to the workpiece. In a laser processing apparatus having a laser beam irradiation means for forming a processing groove and a processing chamber covering the chuck table and the laser beam irradiation means, the laser beam irradiation means sucks dust generated near the processing point by the laser beam irradiation. In addition, the processing chamber is further equipped with a dust discharge means, and the processing chamber is equipped with a cleanliness monitor that measures the amount of dust scattered in the air in the processing chamber and outputs the measurement results. It can be confirmed that the suction and discharge of dust generated near the processing point is insufficient by outputting that the dust measured above the specified value is measured by the monitor. A laser processing apparatus is provided.

  According to the present invention, it is possible to easily find out that dust (debris) is not sufficiently discharged even during processing by a simple configuration in which a cleanliness monitoring monitor is installed in the processing chamber. In addition, it is possible to prevent the occurrence of defects that produce a large amount of wafers to which a large amount of dust (debris) has adhered.

It is a perspective view of the whole structure of the laser processing apparatus of this embodiment. It is a perspective view shown about a to-be-processed object. It is a side view explaining the structure of a laser beam irradiation unit. It is a figure which shows the condition where debris scatters at the time of abnormality.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the appearance of a laser processing apparatus 2 as an embodiment of the present invention.

  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 scheduled division line S1 and the second scheduled division line S2 are formed so as to be orthogonal to each other. A large number of devices D are formed in a region partitioned by S1 and the second scheduled division line S2. In the present embodiment, the surface of the device D (the surface of the wafer W) is protected by a protective film (not shown). The workpiece is not limited to the semiconductor wafer W (silicon wafer) but includes a sapphire wafer, an optical device wafer, and the like.

  As shown in FIG. 2, 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 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 wafer cassette 8, a loading / unloading means 10 is provided 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. Positioning means 14 for positioning to the position of is arranged.

  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 transfer means 16 having a turning arm that sucks and transfers 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 transfer means 16 and transferred to the protective film coating apparatus 30. In the protective film coating apparatus 30, the processed surface of the wafer W is coated with a protective film. This protective film is formed by applying a water-soluble resin such as PVA (polyvinyl alcohol) or PEG (polyethylene glycol).

  The wafer W whose processing surface is coated with a protective film is attracted by the transport means 32 and transported onto the chuck table 18 and 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 move in the X-axis direction by a processing feed means (not shown), and is configured to move inside and outside the processing chamber 27. Further, it is configured to be movable in the Y-axis direction by a Y-axis feed moving means (not shown). The chuck table 18 is configured to be rotatable by a rotating means (not shown) so that the angle of the chuck table 18 can be changed.

  The processing chamber 27 is closed by a cover 25 that can be opened and closed, thereby forming a sealed space. In order to move the chuck table 18 in and out of the processing chamber 27, a passage that is opened and closed by a shutter (not shown) is formed.

  An exhaust unit having an exhaust hose 44 and the like is provided in the processing chamber 27. The dust in the processing chamber 27 is discharged from the exhaust unit to the outside, and the weight of the dust in the air in the processing chamber 27. (For example, weight per cubic meter) can be made lower than a predetermined level.

  In the processing chamber 27, a cleanliness monitoring monitor 40 that measures the amount of dust scattered in the air in the processing chamber 27 and outputs the measurement result is provided. In the present embodiment, as will be described in detail later, it is installed for the purpose of detecting debris scattered in the processing chamber 27.

  In the processing chamber 27, a laser beam irradiation unit 24 that irradiates a laser beam onto the wafer W transferred into the processing chamber 27 by the chuck table 18 is disposed. The casing 26 of the laser beam irradiation unit 24 contains known laser beam oscillation means and the like, and a condenser 28 for condensing the laser beam on the wafer to be processed is attached to the tip of the casing 26. Yes.

  The casing 26 of the laser beam irradiation unit 24 is configured to be movable in the Z-axis direction by a Z-axis direction moving unit (not shown). The casing 26 is provided with imaging means (not shown), and alignment for aligning the irradiation position of the laser beam by the laser beam irradiation unit 24 and the scheduled division line is performed based on the image captured by the imaging means. It has come to be.

Next, a characteristic configuration of the present invention will be described in detail.
As shown in FIG. 3, the wafer W is sucked and held by the chuck table 18 through the dicing tape T, and irradiated with the laser beam LB in the process of being fed under the laser beam irradiation unit 24 in the direction of the arrow X1. A linear laser processing groove K is formed in W along the planned division line. Such processing is known as laser ablation processing.

  In addition, after the processing is fed to the arrow X1 and laser processing is performed on a certain division line, the chuck table 18 is indexed in the Y-axis direction (see FIG. 1) and positioned with respect to the next division line. . The chuck table 18 is processed and fed in the direction of the arrow X2 by a driving device (not shown).

  As described above, the chuck table 18 is processed and fed in both directions of the arrows X1 and X2, whereby the wafer W is reciprocated. FIG. 3 shows a state in which the chuck table 18 is processed and fed in the direction of the arrow X1.

  The laser beam irradiation unit 24 is configured to irradiate the wafer W with a laser beam LB from a condensing lens 42 disposed in the condenser 28.

  A hollow suction block 43 is disposed below the condenser 28. A suction port 43a penetrating in the vertical direction is formed on the lower surface of the suction block 43, and the wafer W is irradiated with the laser beam LB through the suction port 43a.

  As described in the present embodiment, by adopting an arrangement configuration in which the laser beam LB passes through the suction port 43a, the debris 5 generated near the processing point can be efficiently sucked as will be described later.

  An exhaust hose 44 for exhausting the air in the suction block 43 is connected to the upper surface of the suction block 43. The exhaust hose 44 is connected to an exhaust suction source (not shown) so that the inside of the suction block 43 becomes a negative pressure space, and external air is sucked from the suction port 43a.

  In the above configuration, debris 5 (dust) such as smoke generated by vaporization of the wafer W and the protective film by the laser processing (laser ablation processing) is sucked into the suction block 43 from the suction port 43a, and further Then, the air is discharged to the outside of the suction block 43 through the exhaust hose 44.

  By providing the suction block 43 configured as described above, a dust discharge means for sucking and discharging the debris 5 (dust) generated near the processing point by the irradiation of the laser beam LB is configured.

  Further, the processing chamber 27 in which the laser beam irradiation unit 24 described above is accommodated is configured as a sealed space, and the weight of the dust in the processing chamber 27 is measured by the cleanliness monitoring monitor 40. ing.

  In the cleanliness monitor 40, for example, the number of dust per cubic meter is measured, and this measured value is output to a control device (not shown).

  When the measured value is larger than a predetermined value set in advance, that is, when the amount of dust in the processing chamber 27 is large, the cleanliness monitoring monitor 40 determines that an abnormality has occurred and performs control. An error signal for outputting that dust of a predetermined value or more has been measured is output to the apparatus, or an actual measurement value is output. In response to this output, the control device displays a warning on the display means 6 (see FIG. 1), generates a warning, and the like, and temporarily stops the machining in addition to these.

  In such a situation, as shown in FIG. 4, for example, a failure occurs in an exhaust suction source (not shown), the suction force by the exhaust hose 44 is reduced, and the debris 5 is sufficiently sucked from the suction port 43. This occurs when the debris 5 is scattered in the processing chamber 27.

  As described above, by monitoring the amount of the debris 5 being processed in the processing chamber 27 by the cleanliness monitoring monitor 40, it is possible to grasp the occurrence state of debris and the suction / discharge state during the laser processing. Is possible. Note that it is preferable that the threshold value of the measurement value for defining the occurrence of abnormality in the cleanliness monitoring monitor 40 can be arbitrarily set as appropriate depending on the type of the wafer W and the type of the protective film.

The present invention can be implemented as described above.
That is, the chuck table 18 that holds the wafer W as a workpiece, and the laser beam LB having an absorptive wavelength are applied to the surface of the wafer W held by the chuck table 18 to form the laser processing groove K. In a laser processing apparatus including a laser beam irradiation unit (laser beam irradiation means) 24 and a processing chamber 27 covering the chuck table 18 and the laser beam irradiation unit 24, the laser beam irradiation unit 24 is processed by irradiation with a laser beam LB. A suction block (dust discharge means) 43 that sucks and discharges debris (dust) 5 generated near the point is further provided, and the processing chamber 27 stores the amount of debris 5 scattered in the air in the processing chamber 27. A cleanliness monitoring monitor 40 for measuring and outputting the measurement results is provided. 0 by outputting the more dust predetermined is measured, and identifiable laser processing apparatus 2 that is insufficient suction and discharge of dust to be generated in the vicinity of the machining point.

  As described above, the simple configuration in which the cleanliness monitoring monitor 40 is installed in the processing chamber 27 enables early detection that the debris 5 is not sufficiently discharged even during processing. It is possible to prevent the occurrence of defects that produce a large amount of wafers to which a large amount of debris 5 has adhered.

  As described above, the amount of debris 5 in the processing chamber 27 is monitored, and an abnormality is detected by increasing the amount of debris 5. In addition, debris passing through the exhaust hose 44 is used. The amount of 5 may be monitored, and the abnormality detection may be performed with the decrease of the debris 5.

  The cleanliness monitoring monitor 40 may be provided on the wall surface of the processing chamber 27, or may be provided on the wall surface of the suction block 43 or in the vicinity of the suction port 43a. As a result, the suction force from the suction port 43a is weakened, and it is possible to detect earlier that the problem of suction of the debris 5 has occurred.

2 Laser processing device 5 Debris 18 Chuck table 24 Laser beam irradiation unit 40 Cleanliness monitoring monitor 43 Suction block 43a Suction port 44 Exhaust hose K Laser processing groove LB Laser beam

Claims (1)

A chuck table for holding the workpiece;
A laser beam irradiation means for irradiating the surface of the workpiece held by the chuck table with a laser beam having a wavelength that is absorptive with respect to the workpiece to form a laser processing groove;
In a laser processing apparatus comprising a processing chamber covering the chuck table and the laser beam irradiation means,
The laser beam irradiation means
It further comprises dust discharging means for sucking and discharging dust generated near the processing point by laser beam irradiation,
In the processing chamber,
A cleanliness monitor that measures the amount of the dust scattered in the air in the processing chamber and outputs the measurement result is provided,
A laser processing apparatus capable of confirming that suction and discharge of dust generated in the vicinity of a processing point is insufficient by outputting that the cleanliness monitoring monitor has measured dust of a predetermined value or more.

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