JP2014236157A - Laser-machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser-processing device having a transporting mechanism which allows a wafer unit to be transported from holding means with a wafer remaining set on the wafer unit without breaking the wafer.SOLUTION: A laser-processing device comprises: holding means for holding a wafer unit prepared by making an adhesive tape adhere to an annular frame for housing a wafer and then, putting the wafer on the adhesive tape; laser-beam-applying means for applying a laser beam to the wafer set on the wafer unit to form a modified layer inside the wafer; and a transporting mechanism for transporting the wafer unit from the holding means. The transporting mechanism includes: frame-holding means for attracting and holding the annular frame; wafer-holding means for attracting and holding an entire surface of the wafer; and displacement means for supporting and displacing the frame-holding means and the wafer-holding means. In transporting the wafer unit, the wafer-holding means attracts and holds the wafer having the modified layer formed thereinside, and the frame-holding means attracts and holds the annular frame.

Description

  The present invention relates to a laser processing apparatus including a transport mechanism for transporting a wafer such as a semiconductor wafer adhered to an adhesive tape mounted on an annular support frame.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by division lines arranged in a lattice pattern on the surface of a substantially disc-shaped semiconductor wafer, and devices such as ICs and LSIs are formed in the partitioned regions. . Then, the semiconductor wafer is cut along the streets to divide the region in which the device is formed to manufacture individual semiconductor devices.

  As a method of dividing the semiconductor wafer along the planned dividing line of the semiconductor wafer, a laser processing method using a pulsed laser beam having transparency to the wafer and irradiating the pulsed laser beam with a condensing point positioned inside the region to be divided Has been tried. The dividing method using this laser processing method is to irradiate a pulse laser beam having a wavelength that is transparent to the wafer by aligning the condensing point from one side of the wafer to the inside of the wafer. The reformed layer is continuously formed along the street, and an external force is applied along the street where the strength is reduced by the formation of the modified layer. Are divided. As described above, when the semiconductor wafer is divided by the dicing apparatus, the semiconductor wafer is previously supported on the annular frame via the adhesive tape so that the divided semiconductor chips do not fall apart. The annular frame includes an opening for accommodating the wafer and a tape adhering portion to which an adhesive tape is adhered, and supports the wafer by adhering the wafer to the adhesive tape located at the opening. The wafer thus supported on the annular frame via the adhesive tape is transported to the next process by the transport mechanism after the modified layer is formed on the chuck table.

  As described above, a modified layer is formed inside the wafer along the planned division line by irradiating the wafer with a pulsed laser beam having a wavelength that is transmissive to the wafer from one surface side of the wafer. A laser processing apparatus for holding a wafer unit in which an adhesive tape is adhered to an annular frame having an opening for accommodating a wafer and the wafer is adhered to the adhesive tape in the opening; and Laser beam irradiating means for forming a modified layer inside the wafer by irradiating a laser beam having a wavelength that is transparent to the wafer of the held wafer unit, and the modified layer inside the wafer while being held by the holding means A transport mechanism for sucking and holding an annular frame that supports the wafer formed with an adhesive tape and transporting the wafer unit from the holding means; It is provided (for example, see Patent Document 1).

JP 2007-2011178 A

  Thus, after the modified layer is formed inside the wafer, when the annular frame is sucked and held and transported, a force that curves the wafer due to the bending of the adhesive tape acts. If the thickness is small, there is a problem that the wafer is damaged.

  The present invention has been made in view of the above-mentioned facts, and the main technical problem thereof is that the wafer unit is formed from the holding means without damaging the wafer in which the modified layer is formed inside while being held by the holding means. It is providing the laser processing apparatus provided with the conveyance mechanism which can be conveyed in a state.

In order to solve the above main technical problem, according to the present invention, an adhesive tape is adhered to an annular frame having an opening for accommodating a wafer, and a wafer unit in which the wafer is adhered to the adhesive tape in the opening is held. Holding means, laser beam irradiating means for forming a modified layer inside the wafer by irradiating the wafer of the wafer unit held by the holding means with a laser beam having a wavelength, and holding on the holding means In a laser processing apparatus comprising a transport mechanism that transports the wafer unit that has been transported from the holding means,
The transport mechanism comprises frame holding means for sucking and holding the annular frame, wafer holding means for sucking and holding the entire surface of the wafer, and moving means for supporting and moving the frame holding means and the wafer holding means. The wafer having the modified layer formed therein is sucked and held by the wafer holding means, and the annular frame is sucked and held by the frame holding means, and the wafer unit is conveyed from the holding means.
A laser processing apparatus is provided.

  In the laser processing apparatus according to the present invention, the transport mechanism for transporting the wafer unit from the holding means includes a frame holding means for sucking and holding the annular frame, a wafer holding means for sucking and holding the entire surface of the wafer, and a frame holding means. The wafer holding means supports and moves the wafer, and the wafer having the reformed layer formed therein is sucked and held by the wafer holding means, and the annular frame is sucked and held by the frame holding means. Since the unit is transported from the holding means, no load is applied to the wafer, so that even if a reformed layer is formed inside the wafer, it is not damaged.

The perspective view of the laser processing apparatus comprised according to this invention. The perspective view of the 2nd conveyance mechanism as a conveyance mechanism with which the laser processing apparatus shown in FIG. 1 is equipped. FIG. 3 is a cross-sectional view of main parts of a second transport mechanism shown in FIG. 2. Sectional drawing which shows the use condition of the 2nd conveyance mechanism shown in FIG. The perspective view of the 1st conveyance mechanism as a conveyance mechanism with which the laser processing apparatus shown in FIG. 1 is equipped. Explanatory drawing of the modified layer formation process implemented with the laser processing apparatus shown in FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a laser processing apparatus configured according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a laser processing apparatus constructed according to the present invention.
The laser processing apparatus shown in FIG. 1 includes a substantially rectangular parallelepiped apparatus housing 2. In the apparatus housing 2, a chuck table 3 as a holding means for holding a workpiece is disposed so as to be movable in a direction indicated by an arrow X that is a cutting feed direction. The chuck table 3 includes a suction chuck support 31 and a suction chuck 32 mounted on the suction chuck support 31, and is a workpiece on a holding surface that is the upper surface of the suction chuck 32. A disk-shaped semiconductor wafer is held by suction means (not shown). The chuck table 3 is configured to be rotatable by a rotation mechanism (not shown). The suction chuck support 31 of the chuck table 3 configured as described above is provided with a clamp 34 for fixing an annular frame described later.

  The illustrated laser processing apparatus includes a laser beam irradiation means 4. The laser beam irradiation unit 4 includes a laser beam oscillation unit 41 and a condenser 42 that condenses the laser beam oscillated by the laser beam oscillation unit 41. The laser beam oscillating means 41 oscillates a pulsed laser beam having a wavelength that is transparent to a wafer described later.

  The illustrated laser processing apparatus images the surface of the workpiece held on the suction chuck 32 of the chuck table 3 and defines a region to be processed by the laser beam irradiated from the condenser 42 of the laser beam irradiation means 4. An imaging means 5 for detection is provided. In addition to a normal imaging device (CCD) that captures an image with visible light, the imaging unit 5 includes an infrared illumination unit that irradiates a workpiece with infrared rays, an optical system that captures infrared rays emitted by the infrared illumination unit, An image sensor (infrared CCD) that outputs an electrical signal corresponding to infrared rays captured by the optical system is used, and the captured image signal is sent to control means (not shown). In addition, the illustrated laser beam machine 1 includes a display unit 6 that displays an image captured by the imaging unit 5.

  The laser processing apparatus in the illustrated embodiment includes a cassette 7 for stocking a wafer unit 100 including a semiconductor wafer 8 as a wafer, an annular frame 9 and an adhesive tape 10. The annular frame 9 is made of a metal material such as stainless steel, and is formed on the back surface in the state of FIG. 1 with an opening 91 for housing a semiconductor wafer and a tape attaching portion 92 to which the adhesive tape 10 is attached. Have). The pressure-sensitive adhesive tape 10 has a pressure-sensitive adhesive layer on the upper surface and is attached to a tape adhering portion 92 so as to cover the opening 91, and the surface of the semiconductor wafer 8 is adhered to the upper surface of the pressure-sensitive adhesive tape 10. The semiconductor wafer 8 is divided into a plurality of areas by a plurality of streets 81 arranged in a lattice pattern on the surface, and devices 82 such as ICs and LSIs are formed in the divided areas. The surface of the semiconductor wafer 8 configured as described above is adhered to the upper surface of the adhesive tape 10. Therefore, the back surface of the semiconductor wafer 8 attached to the upper surface of the adhesive tape 10 is the upper side. As described above, the wafer unit 100 including the semiconductor wafer 8, the annular frame 9 and the adhesive tape 10 is accommodated in the cassette 7. Further, the cassette 7 is placed on a cassette table 71 that is movably moved up and down by a lifting / lowering means (not shown) in the cassette placing portion 70.

  The cutting apparatus in the illustrated embodiment is carried to the temporary placing means 11 by the workpiece unloading means 12 for unloading the wafer unit 100 accommodated in the cassette 7 to the temporary placing means 11. A first transport mechanism 13 for transporting the wafer unit 100 onto the chuck table 3; a cleaning means 14 for cleaning the wafer unit 100 on which the semiconductor wafer 8 has been laser-processed on the chuck table 3; 2 includes a second transport mechanism 15 for transporting the wafer unit 100 in which the semiconductor wafer 8 has been subjected to laser processing to the cleaning means 14.

Next, the 2nd conveyance mechanism 15 is demonstrated with reference to FIG. 2 and FIG.
The second transport mechanism 15 in the illustrated embodiment includes an operating arm 151. One end of the operating arm 151 is connected to a conventionally used reciprocating means (not shown). A suction holding mechanism 20 is attached to the other end of the operating arm 151. The suction holding mechanism 20 includes an H-shaped support member 21, frame holding means 22 disposed on the support member 21 for sucking and holding the annular frame 9, and the annular frame 9 via the adhesive tape 10. Wafer holding means 23 for sucking and holding the entire surface of the supported semiconductor wafer 8 is provided. A vacuum distributor 152 is disposed on the upper surface of the central support portion 211 of the support member 21. The vacuum distributor 152 is connected to a suction means (not shown) via a flexible pipe 153, and communicates with a suction source as appropriate. A lifting / lowering means 154 is disposed between the vacuum distributor 152 disposed on the support member 21 and the operating arm 151. The elevating means 154 is composed of, for example, an air piston.

  The frame holding means 22 disposed on the support member 21 includes four suction pads 221, 221, 221 and 221 mounted on both side support portions 212 and 212 of the H-shaped support member 21. Yes. The four suction pads 221, 221, 221, 221 are attached to the lower ends of support rods 213, 213, 213, 213 that are slidable in the vertical direction on both side support portions 212, 212, respectively. The coil springs 214, 214, 214, 214 disposed between the lower side support portions 212, 212 are biased to be pressed downward. The four suction pads 221, 221, 221, and 221 thus mounted with the H-shaped support member 21 are communicated with the vacuum distributor 152 through the flexible pipes 222, 222, 222, and 222. Yes.

  The wafer holding means 23 is attached to the lower ends of support rods 215, 215, and 215 that are slidable in the vertical direction on attachment portions 211a and 211b provided on a central support portion 211 that constitutes the support member 21. The coil springs 216, 216, and 216 disposed between the lower surfaces of the attachment portions 211a and 211b are urged to be pressed downward (see FIG. 3). As shown in FIG. 3, the wafer holding unit 23 includes a base 231 and a pad 232 attached to the base 231. The base 231 is provided with a circular recess 231a having an open bottom, and a pad 232 formed in a disk shape by a porous ceramic member is fitted into the circular recess 231a. Thus, the lower surface of the pad 232 fitted into the recess 231a of the base 231 functions as a suction surface for sucking and holding the wafer. The base 231 is provided with a suction passage 231b that communicates with the recess 231a. The suction passage 231b communicates with the vacuum distributor 152 via the flexible pipe 233. In the wafer holding means 23 configured as described above, the upper surface of the base 231 is attached to the lower ends of the support rods 215, 215, and 215 described above.

  The second transport mechanism 15 is configured as described above, and sucks and holds the wafer unit 100 including the semiconductor wafer 8, the annular frame 9, and the adhesive tape 10, as shown in FIG. That is, as shown in FIG. 4, the suction pad 221 of the frame holding means 22 constituting the suction holding mechanism 20 of the second transport mechanism 15 is brought into contact with the upper surface of the annular frame 9 and the pad 232 of the wafer holding means 23 is The lower surface is brought into contact with the upper surface of the semiconductor wafer 8. Then, the suction means (not shown) is operated to apply a negative pressure to the suction pad 221 of the frame holding means 22 and the pad 232 of the wafer holding means 23, whereby the annular frame 9 is sucked and held by the suction pad 221. By 232, the entire upper surface of the semiconductor wafer 8 is sucked and held.

Next, the first transport mechanism 13 will be described with reference to FIG.
The first transport mechanism 13 in the illustrated embodiment includes an L-shaped operating arm 131. One end of the L-shaped operating arm 131 is connected to the lifting means 132. The elevating means 132 is made of, for example, an air piston, and operates the operating arm 131 in the vertical direction as indicated by an arrow 130a in FIG. Further, the lifting / lowering means 132 connected to one end of the operating arm 131 is connected to a moving means 133 including an electric motor capable of normal rotation and reverse rotation. Therefore, by driving the moving means 133 in the forward rotation direction or the reverse rotation direction, the operating arm 131 is swung in the direction indicated by the arrow 130b in FIG.

  A suction holding mechanism 20 is attached to the other end of the operating arm 131. Similar to the suction holding mechanism 20 of the second transport mechanism 15, the suction holding mechanism 20 includes an H-shaped support member 21 and a frame holding means disposed on the support member 21 for sucking and holding the annular frame 9. 22 and wafer holding means 23 for sucking and holding the entire surface of the semiconductor wafer 8 supported by the annular frame 9 via the adhesive tape 10. A vacuum distributor 152 is disposed on the upper surface of the central support portion 211 of the support member 21, and the vacuum distributor 152 is attached to the operating arm 131. The frame holding means 22 and the wafer holding means 23 constituting the first transfer mechanism 13 are substantially the same as the frame holding means 22 and the wafer holding means 23 of the second transfer mechanism 15 shown in FIGS. Therefore, the same members are denoted by the same reference numerals, and the description thereof is omitted.

The laser processing apparatus configured according to the present invention is configured as described above, and the operation thereof will be described below with reference to FIG.
The wafer unit 100 composed of the semiconductor wafer 8, the annular frame 9 and the adhesive tape 10 accommodated in a predetermined position of the cassette 7 is positioned at the carry-out position when the cassette table 71 moves up and down by lifting means (not shown). Next, the workpiece unloading means 12 moves forward and backward to unload the wafer unit 100 positioned at the unloading position to the temporary placement means 11. The wafer unit 100 transported to the temporary placing means 11 is sucked by the frame holding means 22 and the wafer holding means 23 by operating the lifting means 132, the moving means 133 and the suction means (not shown) constituting the first transport mechanism 13. Retained. That is, the annular frame 9 is sucked and held by the frame holding means 22 constituting the first transport mechanism 13, and the entire upper surface of the semiconductor wafer 8 is sucked and held by the wafer holding means 23. Thus, the wafer unit 100 sucked and held by the frame holding means 22 and the wafer holding means 23 constituting the first carrying mechanism 13 is carried on the holding surface of the suction chuck 32 constituting the chuck table 3. The

  The wafer unit 100 transported onto the chucking chuck 32 of the chuck table 3 by the first transport mechanism 13 is released from the suction and holding by the frame holding means 22 and the wafer holding means 23 constituting the first transport mechanism 13. . Then, when the suction means (not shown) is operated, the semiconductor wafer 8 is sucked and held on the holding surface of the suction chuck 32 via the adhesive tape 10, and the annular frame 9 is fixed by the clamp 34. In this way, the chuck table 3 holding the wafer unit 100 is moved to a position directly below the imaging mechanism 5.

  When the chuck table 3 is positioned immediately below the imaging mechanism 5, an alignment operation for detecting a processing region to be laser-processed of the semiconductor wafer 8 is executed by the imaging means 5 and a control means (not shown). That is, the imaging unit 5 and the control unit (not shown) align the street 81 formed in a predetermined direction of the semiconductor wafer 8 with the condenser 42 of the laser beam irradiation unit 4 that irradiates the laser beam along the street 81. Image processing such as pattern matching is performed to perform the laser beam irradiation position alignment (alignment process). The alignment of the laser beam irradiation position is similarly performed on the street 81 formed on the semiconductor wafer 8 in a direction orthogonal to the predetermined direction. At this time, the surface of the semiconductor wafer 8 on which the streets 81 are formed is located on the lower side. However, as described above, the imaging unit 5 generates an infrared illumination unit, an optical system for capturing infrared rays, and an electrical signal corresponding to the infrared rays. Since the image pickup means including an image pickup device (infrared CCD) for outputting is provided, the street 81 can be picked up through the back surface of the semiconductor wafer 8.

  When the alignment step described above is performed, the chuck table 3 is moved to the laser beam irradiation region where the condenser 42 of the laser beam irradiation means 4 for irradiating the laser beam is positioned as shown in FIG. It is positioned directly below the vessel 42. At this time, as shown in FIG. 6A, the semiconductor wafer 8 is positioned so that one end of the street 81 (the left end in FIG. 6A) is located directly below the condenser 42. Next, the condensing point P of the pulse laser beam irradiated from the concentrator 42 is positioned in the middle part in the thickness direction of the semiconductor wafer 8. Then, the chuck table 3 is moved at a predetermined feed speed in the direction indicated by the arrow X1 in FIG. 6A while irradiating the semiconductor wafer 8 with a pulse laser beam having a wavelength transmissive from the condenser 42 (see FIG. 6A). Modified layer forming step). When the other end of the street 81 (the right end in FIG. 6A) reaches the irradiation position of the condenser 42 of the laser beam irradiation means 4 as shown in FIG. At the same time, the movement of the chuck table 3 is stopped. As a result, the modified layer 33 is formed along the street 81 inside the semiconductor wafer 8.

The processing conditions in the modified layer forming step are set as follows, for example.
Wavelength: 1064 nm pulse laser Repeat frequency: 80 kHz
Average output: 0.2W
Processing feed rate: 180 mm / sec

  When the modified layer forming step is performed along the predetermined street 81 as described above, the chuck table 3 is indexed and moved in the direction indicated by the arrow Y by the interval of the street 81 formed on the semiconductor wafer 8 (indexing step). The modified layer forming step is performed. If the modified layer forming step is performed along all the streets 81 formed in the predetermined direction in this way, the chuck table 3 is rotated 90 degrees to make the streets 81 formed in the predetermined direction. The modified layer forming step is executed along the street 81 formed in a direction orthogonal to the direction.

  When the modified layer forming step is performed as described above, the chuck table 3 holding the wafer unit 100 is first returned to the position where the wafer unit 100 is held, and the suction holding of the semiconductor wafer 8 is released here. . Then, the fixing of the annular frame 9 by the clamp 34 is also released.

  Next, the wafer unit 100 in which the suction and holding of the semiconductor wafer 8 is released on the chuck table 3 and the fixation of the annular frame 9 by the clamp 34 is released, the suction and holding mechanism 20 of the second transport mechanism 15 is moved. It is sucked and held by the frame holding means 22 and the wafer holding means 23 that constitute it. That is, by operating the lifting and lowering means 154 and the reciprocating mechanism (not shown) constituting the second transport mechanism 15, the suction pad 221 of the frame holding means 22 is brought into contact with the upper surface of the annular frame 9 as shown in FIG. Then, the pad 232 of the wafer holding means 23 is brought into contact with the upper surface of the semiconductor wafer 8. Then, the suction means (not shown) is operated to apply a negative pressure to the suction pad 221 of the frame holding means 22 and the pad 232 of the wafer holding means 23, whereby the annular frame 9 is sucked and held by the suction pad 221. The entire upper surface of the semiconductor wafer 8 is sucked and held by the lower surface of 232. The wafer unit 100 sucked and held by the suction pad 221 of the frame holding means 22 and the pad 232 of the wafer holding means 23 in this way is conveyed to the cleaning means 14.

  As described above, when the wafer unit 100 is transported from the chuck table 3 to the cleaning means 14 by the second transport mechanism 15, the annular frame 9 is sucked and held by the suction pad 221 of the frame holding means 22 and the wafer is also held. Since the entire upper surface of the semiconductor wafer 8 is sucked and held by the pad 232 of the holding means 23, no load is applied to the semiconductor wafer 8, so that even if a modified layer is formed along the street 81 inside the semiconductor wafer 8, it is damaged. There is nothing.

  The wafer unit 100 conveyed to the cleaning unit 14 as described above is cleaned by the cleaning unit 14. The wafer unit 100 cleaned by the cleaning means 14 is transported to the temporary placement means 11 by the first transport mechanism 13. At this time, the wafer unit 100 is sucked and held by the frame holding means 22 and the wafer holding means 23 constituting the suction holding mechanism 20 of the first transport mechanism 13. That is, the annular frame 9 is sucked and held by the suction pad 221 of the frame holding means 22 and the entire upper surface of the semiconductor wafer 8 is sucked and held by the pad 232 of the wafer holding means 23 as in the second transport mechanism 15 described above. The Accordingly, since no load is applied to the semiconductor wafer 8, even if a modified layer is formed along the street 81 inside the semiconductor wafer 8, the semiconductor wafer 8 is not damaged. In this way, the wafer unit 1008 conveyed to the temporary placement means 11 is accommodated in a predetermined position of the cassette 7 by the workpiece unloading means 12.

2: Device housing 3: Chuck table 4: Laser beam irradiation means 41: Laser beam oscillation means 42: Condenser 5: Imaging means 6: Display means 7: Cassette 71: Cassette table 8: Semiconductor wafer 9: Ring frame 10: Adhesive Tape 100: Wafer unit 11: Temporary placing means 12: Workpiece unloading means 13: First conveying mechanism 131: Operating arm 132: Lifting means 133: Moving means 14: Cleaning means 15: Second conveying mechanism 151: Operation Arm 152: Vacuum distributor 154: Lifting means 20: Suction holding mechanism 21: Support member 22: Frame holding means 23: Wafer holding means

Claims (1)

A holding means for holding a wafer unit in which an adhesive tape is adhered to an annular frame having an opening for accommodating a wafer and the wafer is adhered to the adhesive tape in the opening, and a wafer unit held by the holding means. A laser beam irradiation means for irradiating the wafer with a laser beam having a wavelength having transparency, and forming a modified layer inside the wafer; a transport mechanism for transporting the wafer unit held by the holding means from the holding means; In a laser processing apparatus comprising:
The transport mechanism comprises frame holding means for sucking and holding the annular frame, wafer holding means for sucking and holding the entire surface of the wafer, and moving means for supporting and moving the frame holding means and the wafer holding means. The wafer having the modified layer formed therein is sucked and held by the wafer holding means, and the annular frame is sucked and held by the frame holding means, and the wafer unit is conveyed from the holding means.
Laser processing equipment characterized by that.

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